/* * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved. * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved. * Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved. * Copyright (c) 2008-2022 Ivan Maidanski * * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. * * Permission is hereby granted to use or copy this program * for any purpose, provided the above notices are retained on all copies. * Permission to modify the code and to distribute modified code is granted, * provided the above notices are retained, and a notice that the code was * modified is included with the above copyright notice. */ #include "private/gc_priv.h" #if (defined(MPROTECT_VDB) && !defined(MSWIN32) && !defined(MSWINCE)) \ || (defined(SOLARIS) && defined(THREADS)) || defined(OPENBSD) # include #endif #if defined(UNIX_LIKE) || defined(CYGWIN32) || defined(NACL) \ || defined(SYMBIAN) # include #endif #ifdef LINUX # include #endif /* * Blatantly OS-dependent routines, except for those that are related * to dynamic loading. */ #ifdef IRIX5 # include /*< for locking */ # include #endif #if defined(MMAP_SUPPORTED) || defined(ADD_HEAP_GUARD_PAGES) # if defined(USE_MUNMAP) && !defined(USE_MMAP) && !defined(CPPCHECK) # error Invalid config: USE_MUNMAP requires USE_MMAP # endif # include # include #endif #if defined(LINUX) && defined(SPECIFIC_MAIN_STACKBOTTOM) \ || defined(ADD_HEAP_GUARD_PAGES) || defined(MMAP_SUPPORTED) \ || defined(NEED_PROC_MAPS) # include #endif #if defined(DARWIN) && !defined(DYNAMIC_LOADING) \ && !defined(GC_DONT_REGISTER_MAIN_STATIC_DATA) # include /*< for `get_etext` and friends */ #endif #ifdef DJGPP /* * Apparently necessary for djgpp 2.01. May cause problems with * other versions. */ typedef long unsigned int caddr_t; #endif #if !defined(NO_EXECUTE_PERMISSION) STATIC GC_bool GC_pages_executable = TRUE; #else STATIC GC_bool GC_pages_executable = FALSE; #endif /* Note: it is undefined later on `GC_pages_executable` real use. */ #define IGNORE_PAGES_EXECUTABLE 1 #if ((defined(LINUX) && defined(SPECIFIC_MAIN_STACKBOTTOM) \ || defined(NEED_PROC_MAPS) || defined(PROC_VDB) || defined(SOFT_VDB)) \ && !defined(PROC_READ)) \ || defined(CPPCHECK) /* Note: should probably call the real `read()`, if later is wrapped. */ # define PROC_READ read #endif #if defined(LINUX) && defined(SPECIFIC_MAIN_STACKBOTTOM) \ || defined(NEED_PROC_MAPS) /* * Repeatedly perform a `read()` call until the buffer is filled up, * or we encounter EOF (end of file) or an error. */ STATIC ssize_t GC_repeat_read(int f, char *buf, size_t count) { size_t num_read = 0; ASSERT_CANCEL_DISABLED(); while (num_read < count) { ssize_t result = PROC_READ(f, buf + num_read, count - num_read); if (result < 0) return result; if (0 == result) break; # ifdef LINT2 if ((size_t)result > count - num_read) ABORT("read() result cannot be bigger than requested length"); # endif num_read += (size_t)result; } return num_read; } #endif /* LINUX && SPECIFIC_MAIN_STACKBOTTOM || NEED_PROC_MAPS */ #ifdef NEED_PROC_MAPS /* * We need to parse `/proc/self/maps` pseudo-file, either to find * dynamic libraries, and/or to find the register backing store * base (the IA-64 case). Do it once here. */ # ifndef SINGLE_THREADED_PROCESS /* * Determine the length of a file by incrementally reading it into a buffer. * This would be silly to use it on a file supporting `lseek`, but Linux * `/proc` files usually do not. As of Linux 4.15.0, `lseek(SEEK_END)` fails * for `/proc/self/maps` file. */ STATIC size_t GC_get_file_len(int f) { size_t total = 0; # define GET_FILE_LEN_BUF_SZ 500 char buf[GET_FILE_LEN_BUF_SZ]; ASSERT_CANCEL_DISABLED(); for (;;) { ssize_t result = PROC_READ(f, buf, sizeof(buf)); if (result < 0) { /* An error has occurred. */ return 0; } if (0 == result) break; # ifdef LINT2 if ((size_t)result >= GC_SIZE_MAX - total) ABORT("Too big file is passed to GC_get_file_len"); # endif total += (size_t)result; } return total; } STATIC size_t GC_get_maps_len(void) { int f = open("/proc/self/maps", O_RDONLY); size_t result; if (f < 0) { /* Treat missing file as empty. */ return 0; } result = GC_get_file_len(f); close(f); return result; } # endif /* !SINGLE_THREADED_PROCESS */ GC_INNER const char * GC_get_maps(void) { ssize_t result; static char *maps_buf = NULL; static size_t maps_buf_sz = 1; size_t maps_size; # ifndef SINGLE_THREADED_PROCESS size_t old_maps_size = 0; # endif /* The buffer is essentially `static`, so there must be a single client. */ GC_ASSERT(I_HOLD_LOCK()); /* * Note that in the presence of threads in the process (even if the * collector itself is built single-threaded), the `maps` file can * essentially shrink asynchronously and unexpectedly as threads * that we already think of as dead release their stacks. * And there is no easy way to read the entire file atomically. * This is arguably a misfeature of the `/proc/self/maps` interface. * Since we expect the file can grow asynchronously in rare cases, * it should suffice to first determine the size (using `read()`), * and then to reread the file. If the size is inconsistent, then * we have to retry. This only matters with threads enabled, and * if we use this to locate the data roots (not the default). */ # ifndef SINGLE_THREADED_PROCESS /* Determine the initial size of `/proc/self/maps` file. */ maps_size = GC_get_maps_len(); if (0 == maps_size) ABORT("Cannot determine length of /proc/self/maps"); # else maps_size = 4000; /*< guess */ # endif /* * Read `/proc/self/maps` file, growing `maps_buf` as necessary. * Note that we may not allocate conventionally, and thus cannot * use `stdio` functionality. */ do { int f; while (maps_size >= maps_buf_sz) { # ifdef LINT2 /* Workaround passing tainted `maps_buf` to a tainted sink. */ GC_noop1_ptr(maps_buf); # else GC_scratch_recycle_no_gww(maps_buf, maps_buf_sz); # endif /* Grow only by powers of 2, since we leak "too small" buffers. */ while (maps_size >= maps_buf_sz) maps_buf_sz *= 2; maps_buf = GC_scratch_alloc(maps_buf_sz); if (NULL == maps_buf) ABORT_ARG1("Insufficient space for /proc/self/maps buffer", ", %lu bytes requested", (unsigned long)maps_buf_sz); # ifndef SINGLE_THREADED_PROCESS /* * Recompute initial length, since we allocated. * This can only happen a few times per program execution. */ maps_size = GC_get_maps_len(); if (0 == maps_size) ABORT("Cannot determine length of /proc/self/maps"); # endif } GC_ASSERT(maps_buf_sz >= maps_size + 1); f = open("/proc/self/maps", O_RDONLY); if (-1 == f) ABORT_ARG1("Cannot open /proc/self/maps", ": errno= %d", errno); # ifndef SINGLE_THREADED_PROCESS old_maps_size = maps_size; # endif maps_size = 0; do { result = GC_repeat_read(f, maps_buf, maps_buf_sz - 1); if (result < 0) { ABORT_ARG1("Failed to read /proc/self/maps", ": errno= %d", errno); } maps_size += (size_t)result; } while ((size_t)result == maps_buf_sz - 1); close(f); if (0 == maps_size) ABORT("Empty /proc/self/maps"); # ifndef SINGLE_THREADED_PROCESS if (maps_size > old_maps_size) { /* This might be caused by e.g. thread creation. */ WARN("Unexpected asynchronous /proc/self/maps growth" " (to %" WARN_PRIuPTR " bytes)\n", maps_size); } # endif } while (maps_size >= maps_buf_sz # ifndef SINGLE_THREADED_PROCESS || maps_size < old_maps_size # endif ); maps_buf[maps_size] = '\0'; return maps_buf; } /* * `GC_parse_map_entry` parses an entry from `/proc/self/maps` file so we * can locate all writable data segments that belong to shared libraries. * The format of one of these entries and the fields we care about * is as follows: * ``` * XXXXXXXX-XXXXXXXX r-xp 00000000 30:05 260537 name-of-mapping...\n * ^^^^^^^^ ^^^^^^^^ ^^^^ ^^ * *p_start *p_end *p_prot *p_maj_dev * ``` * * Note that since about August 2003 kernels, the columns no longer have * fixed offsets on 64-bit kernels. Hence we no longer rely on fixed * offsets anywhere, which is safer anyway. */ # if defined(DYNAMIC_LOADING) && defined(USE_PROC_FOR_LIBRARIES) \ || defined(IA64) || defined(INCLUDE_LINUX_THREAD_DESCR) \ || (defined(CHECK_SOFT_VDB) && defined(MPROTECT_VDB)) \ || defined(REDIR_MALLOC_AND_LINUXTHREADS) GC_INNER const char * GC_parse_map_entry(const char *maps_ptr, ptr_t *p_start, ptr_t *p_end, const char **p_prot, unsigned *p_maj_dev, const char **p_mapping_name) { const unsigned char *start_start, *end_start, *maj_dev_start; const unsigned char *p; /*< unsigned for `isspace`, `isxdigit` */ if (maps_ptr == NULL || *maps_ptr == '\0') { return NULL; } p = (const unsigned char *)maps_ptr; while (isspace(*p)) ++p; start_start = p; GC_ASSERT(isxdigit(*start_start)); *p_start = (ptr_t)strtoul((const char *)start_start, (char **)&p, 16); GC_ASSERT(*p == '-'); ++p; end_start = p; GC_ASSERT(isxdigit(*end_start)); *p_end = (ptr_t)strtoul((const char *)end_start, (char **)&p, 16); GC_ASSERT(isspace(*p)); while (isspace(*p)) ++p; GC_ASSERT(*p == 'r' || *p == '-'); *p_prot = (const char *)p; /* Skip past protection field to offset field. */ while (!isspace(*p)) ++p; while (isspace(*p)) p++; GC_ASSERT(isxdigit(*p)); /* Skip past offset field, which we ignore. */ while (!isspace(*p)) ++p; while (isspace(*p)) p++; maj_dev_start = p; GC_ASSERT(isxdigit(*maj_dev_start)); *p_maj_dev = strtoul((const char *)maj_dev_start, NULL, 16); if (p_mapping_name != NULL) { while (*p && *p != '\n' && *p != '/' && *p != '[') p++; *p_mapping_name = (const char *)p; } while (*p && *p++ != '\n') { /* Empty. */ } return (const char *)p; } # endif /* REDIRECT_MALLOC || DYNAMIC_LOADING || IA64 || ... */ # if defined(IA64) || defined(INCLUDE_LINUX_THREAD_DESCR) \ || (defined(CHECK_SOFT_VDB) && defined(MPROTECT_VDB)) GC_INNER GC_bool GC_enclosing_writable_mapping(ptr_t addr, ptr_t *startp, ptr_t *endp) { const char *prot; ptr_t my_start, my_end; const char *maps_ptr; unsigned maj_dev; GC_ASSERT(I_HOLD_LOCK()); maps_ptr = GC_get_maps(); for (;;) { maps_ptr = GC_parse_map_entry(maps_ptr, &my_start, &my_end, &prot, &maj_dev, NULL); if (NULL == maps_ptr) break; if (ADDR_INSIDE(addr, my_start, my_end)) { if (prot[1] != 'w' || maj_dev != 0) break; *startp = my_start; *endp = my_end; return TRUE; } } return FALSE; } # endif /* IA64 || INCLUDE_LINUX_THREAD_DESCR */ # ifdef REDIR_MALLOC_AND_LINUXTHREADS GC_INNER GC_bool GC_text_mapping(const char *nm, ptr_t *startp, ptr_t *endp) { size_t nm_len; const char *prot, *map_path; ptr_t my_start, my_end; unsigned int maj_dev; const char *maps_ptr; GC_ASSERT(I_HOLD_LOCK()); maps_ptr = GC_get_maps(); nm_len = strlen(nm); for (;;) { maps_ptr = GC_parse_map_entry(maps_ptr, &my_start, &my_end, &prot, &maj_dev, &map_path); if (NULL == maps_ptr) break; if (prot[0] == 'r' && prot[1] == '-' && prot[2] == 'x') { const char *p = map_path; /* Set `p` to point just past last slash, if any. */ while (*p != '\0' && *p != '\n' && *p != ' ' && *p != '\t') { ++p; } while (ADDR_GE((ptr_t)p, (ptr_t)map_path) && *p != '/') { --p; } ++p; if (strncmp(nm, p, nm_len) == 0) { *startp = my_start; *endp = my_end; return TRUE; } } } return FALSE; } # endif /* REDIR_MALLOC_AND_LINUXTHREADS */ # ifdef IA64 static ptr_t backing_store_base_from_proc(void) { ptr_t my_start, my_end; GC_ASSERT(I_HOLD_LOCK()); if (!GC_enclosing_writable_mapping(GC_save_regs_in_stack(), &my_start, &my_end)) { GC_COND_LOG_PRINTF("Failed to find backing store base from /proc\n"); return 0; } return my_start; } # endif #endif /* NEED_PROC_MAPS */ #if defined(SEARCH_FOR_DATA_START) /* * The i686 case can be handled without a search. The Alpha case used to * be handled differently as well, but the rules changed for recent Linux * versions. This seems to be the easiest way to cover all versions. */ # if defined(LINUX) || defined(HURD) /* * Some Linux distributions arrange to define `__data_start`. * Some define `data_start` as a weak symbol. The latter is technically * broken, since the user program may define `data_start`, in which * case we lose. Nonetheless, we try both, preferring `__data_start`. * We assume gcc-compatible pragmas. */ EXTERN_C_BEGIN # pragma weak __data_start # pragma weak data_start extern int __data_start[], data_start[]; EXTERN_C_END # elif defined(NETBSD) EXTERN_C_BEGIN extern char **environ; EXTERN_C_END # endif ptr_t GC_data_start = NULL; GC_INNER void GC_init_linux_data_start(void) { ptr_t data_end = DATAEND; # if (defined(LINUX) || defined(HURD)) && defined(USE_PROG_DATA_START) /* * Try the easy approaches first. However, this may lead to wrong * data start value if the collector code is put into a shared library * (directly or indirectly) which is linked with `-Bsymbolic-functions` * option. Thus, the following is not used by default. */ if (COVERT_DATAFLOW(ADDR(__data_start)) != 0) { GC_data_start = (ptr_t)(__data_start); } else { GC_data_start = (ptr_t)(data_start); } if (COVERT_DATAFLOW(ADDR(GC_data_start)) != 0) { if (ADDR_LT(data_end, GC_data_start)) ABORT_ARG2("Wrong __data_start/_end pair", ": %p .. %p", (void *)GC_data_start, (void *)data_end); return; } # ifdef DEBUG_ADD_DEL_ROOTS GC_log_printf("__data_start not provided\n"); # endif # endif /* LINUX */ if (GC_no_dls) { /* * Not needed, avoids the `SIGSEGV` caused by `GC_find_limit` which * complicates debugging. */ GC_data_start = data_end; /*< set data root size to 0 */ return; } # ifdef NETBSD /* * This may need to be `environ`, without the underscore, for * some versions. */ GC_data_start = (ptr_t)GC_find_limit(&environ, FALSE); # else GC_data_start = (ptr_t)GC_find_limit(data_end, FALSE); # endif } #endif /* SEARCH_FOR_DATA_START */ #ifdef ECOS # ifndef ECOS_GC_MEMORY_SIZE # define ECOS_GC_MEMORY_SIZE (448 * 1024) # endif /* ECOS_GC_MEMORY_SIZE */ /* * TODO: This is a simple way of allocating memory which is * compatible with ECOS early releases. Later releases use a more * sophisticated means of allocating memory than this simple static * allocator, but this method is at least bound to work. */ static char ecos_gc_memory[ECOS_GC_MEMORY_SIZE]; static ptr_t ecos_gc_brk = ecos_gc_memory; static void * tiny_sbrk(ptrdiff_t increment) { void *p = ecos_gc_brk; if (ADDR_LT((ptr_t)ecos_gc_memory + sizeof(ecos_gc_memory), (ptr_t)p + increment)) return NULL; ecos_gc_brk += increment; return p; } # define sbrk tiny_sbrk #endif /* ECOS */ #if defined(ADDRESS_SANITIZER) \ && (defined(UNIX_LIKE) || defined(NEED_FIND_LIMIT) \ || defined(MPROTECT_VDB)) \ && !defined(CUSTOM_ASAN_DEF_OPTIONS) EXTERN_C_BEGIN GC_API const char *__asan_default_options(void); EXTERN_C_END /* * To tell ASan to allow the collector to use its own `SIGBUS` and `SIGSEGV` * handlers. The function is exported just to be visible to ASan library. */ GC_API const char * __asan_default_options(void) { return "allow_user_segv_handler=1"; } #endif #ifdef OPENBSD static struct sigaction old_segv_act; STATIC JMP_BUF GC_jmp_buf_openbsd; STATIC void GC_fault_handler_openbsd(int sig) { UNUSED_ARG(sig); LONGJMP(GC_jmp_buf_openbsd, 1); } static volatile int firstpass; /* * Return first addressable location that is greater than `p` or return * `bound`. */ STATIC ptr_t GC_skip_hole_openbsd(ptr_t p, ptr_t bound) { static volatile ptr_t result; struct sigaction act; size_t pgsz; GC_ASSERT(I_HOLD_LOCK()); pgsz = (size_t)sysconf(_SC_PAGESIZE); GC_ASSERT(ADDR(bound) >= (word)pgsz); act.sa_handler = GC_fault_handler_openbsd; sigemptyset(&act.sa_mask); act.sa_flags = SA_NODEFER | SA_RESTART; /* `act.sa_restorer` is deprecated and should not be initialized. */ sigaction(SIGSEGV, &act, &old_segv_act); firstpass = 1; result = PTR_ALIGN_DOWN(p, pgsz); if (SETJMP(GC_jmp_buf_openbsd) != 0 || firstpass) { firstpass = 0; if (ADDR_GE(result, bound - pgsz)) { result = bound; } else { /* * Notes: no overflow is expected; do not use compound assignment * with `volatile`-qualified left operand. */ result = result + pgsz; GC_noop1((word)(unsigned char)(*result)); } } sigaction(SIGSEGV, &old_segv_act, 0); return result; } #endif /* OPENBSD */ #ifdef OS2 # include # if !defined(__IBMC__) && !defined(__WATCOMC__) /*< e.g. EMX */ struct exe_hdr { unsigned short magic_number; unsigned short padding[29]; long new_exe_offset; }; # define E_MAGIC(x) (x).magic_number # define EMAGIC 0x5A4D # define E_LFANEW(x) (x).new_exe_offset struct e32_exe { unsigned char magic_number[2]; unsigned char byte_order; unsigned char word_order; unsigned long exe_format_level; unsigned short cpu; unsigned short os; unsigned long padding1[13]; unsigned long object_table_offset; unsigned long object_count; unsigned long padding2[31]; }; # define E32_MAGIC1(x) (x).magic_number[0] # define E32MAGIC1 'L' # define E32_MAGIC2(x) (x).magic_number[1] # define E32MAGIC2 'X' # define E32_BORDER(x) (x).byte_order # define E32LEBO 0 # define E32_WORDER(x) (x).word_order # define E32LEWO 0 # define E32_CPU(x) (x).cpu # define E32CPU286 1 # define E32_OBJTAB(x) (x).object_table_offset # define E32_OBJCNT(x) (x).object_count struct o32_obj { unsigned long size; unsigned long base; unsigned long flags; unsigned long pagemap; unsigned long mapsize; unsigned long reserved; }; # define O32_FLAGS(x) (x).flags # define OBJREAD 0x0001L # define OBJWRITE 0x0002L # define OBJINVALID 0x0080L # define O32_SIZE(x) (x).size # define O32_BASE(x) (x).base # else /* IBM's compiler */ /* A kludge to get around what appears to be a header file bug. */ # ifndef WORD # define WORD unsigned short # endif # ifndef DWORD # define DWORD unsigned long # endif # define EXE386 1 # include # include # endif /* __IBMC__ */ # define INCL_DOSERRORS # define INCL_DOSEXCEPTIONS # define INCL_DOSFILEMGR # define INCL_DOSMEMMGR # define INCL_DOSMISC # define INCL_DOSMODULEMGR # define INCL_DOSPROCESS # include #endif /* OS2 */ GC_INNER size_t GC_page_size = 0; #ifdef REAL_PAGESIZE_NEEDED GC_INNER size_t GC_real_page_size = 0; #endif #ifdef SOFT_VDB STATIC unsigned GC_log_pagesize = 0; #endif #ifdef ANY_MSWIN # ifndef VER_PLATFORM_WIN32_CE # define VER_PLATFORM_WIN32_CE 3 # endif # if defined(MSWINCE) && defined(THREADS) GC_INNER GC_bool GC_dont_query_stack_min = FALSE; # endif GC_INNER SYSTEM_INFO GC_sysinfo; # ifndef CYGWIN32 # define is_writable(prot) \ ((prot) == PAGE_READWRITE || (prot) == PAGE_WRITECOPY \ || (prot) == PAGE_EXECUTE_READWRITE \ || (prot) == PAGE_EXECUTE_WRITECOPY) /* * Return the number of bytes that are writable starting at `p`. * The pointer `p` is assumed to be page-aligned. If `base` is not `NULL`, * then `*base` becomes the beginning of the allocation region containing `p`. */ STATIC word GC_get_writable_length(ptr_t p, ptr_t *base) { MEMORY_BASIC_INFORMATION buf; word result; word protect; result = VirtualQuery(p, &buf, sizeof(buf)); if (result != sizeof(buf)) ABORT("Weird VirtualQuery result"); if (base != 0) *base = (ptr_t)(buf.AllocationBase); protect = buf.Protect & ~(word)(PAGE_GUARD | PAGE_NOCACHE); if (!is_writable(protect) || buf.State != MEM_COMMIT) return 0; return buf.RegionSize; } GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { /* * Note: this function should not acquire the allocator lock as it is * used by `GC_DllMain`. */ ptr_t trunc_sp; word size; /* * Set page size if it is not ready (so client can use this function even * before the collector is initialized). */ if (!GC_page_size) GC_setpagesize(); trunc_sp = PTR_ALIGN_DOWN(GC_approx_sp(), GC_page_size); /* * FIXME: This will not work if called from a deeply recursive * client code (and the committed stack space has grown). */ size = GC_get_writable_length(trunc_sp, 0); GC_ASSERT(size != 0); sb->mem_base = trunc_sp + size; return GC_SUCCESS; } # else /* CYGWIN32 */ GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { /* * An alternate variant for Cygwin (adapted from Dave Korn's gcc version * of boehm-gc). */ # ifdef X86_64 sb->mem_base = ((NT_TIB *)NtCurrentTeb())->StackBase; # else void *_tlsbase; __asm__("movl %%fs:4, %0" : "=r"(_tlsbase)); sb->mem_base = _tlsbase; # endif return GC_SUCCESS; } # endif /* CYGWIN32 */ # define HAVE_GET_STACK_BASE #elif defined(OS2) static int os2_getpagesize(void) { ULONG result[1]; if (DosQuerySysInfo(QSV_PAGE_SIZE, QSV_PAGE_SIZE, (void *)result, sizeof(ULONG)) != NO_ERROR) { WARN("DosQuerySysInfo failed\n", 0); result[0] = 4096; } return (int)result[0]; } #endif /* !ANY_MSWIN && OS2 */ GC_INNER void GC_setpagesize(void) { #ifdef ANY_MSWIN GetSystemInfo(&GC_sysinfo); # ifdef ALT_PAGESIZE_USED /* * Allocations made with `mmap()` are aligned to the allocation * granularity, which (at least on Win64) is not the same as the * page size. Probably we could distinguish the allocation * granularity from the actual page size, but in practice there * is no good reason to make allocations smaller than * `dwAllocationGranularity`, so we just use it instead of the * actual page size here (as Cygwin itself does in many cases). */ GC_page_size = (size_t)GC_sysinfo.dwAllocationGranularity; # ifdef REAL_PAGESIZE_NEEDED GC_real_page_size = (size_t)GC_sysinfo.dwPageSize; GC_ASSERT(GC_page_size >= GC_real_page_size); # endif # else GC_page_size = (size_t)GC_sysinfo.dwPageSize; # endif # if defined(MSWINCE) && !defined(_WIN32_WCE_EMULATION) { OSVERSIONINFO verInfo; /* Check the current WinCE version. */ verInfo.dwOSVersionInfoSize = sizeof(OSVERSIONINFO); if (!GetVersionEx(&verInfo)) ABORT("GetVersionEx failed"); if (verInfo.dwPlatformId == VER_PLATFORM_WIN32_CE && verInfo.dwMajorVersion < 6) { /* * Only the first 32 MB of address space belongs to the * current process (unless WinCE 6.0+ or emulation). */ GC_sysinfo.lpMaximumApplicationAddress = (LPVOID)((word)32 << 20); # ifdef THREADS /* * On some old WinCE versions, it is observed that * `VirtualQuery()` calls do not work properly when used to * get thread current stack committed minimum. */ if (verInfo.dwMajorVersion < 5) GC_dont_query_stack_min = TRUE; # endif } } # endif #else # ifdef ALT_PAGESIZE_USED # ifdef REAL_PAGESIZE_NEEDED GC_real_page_size = (size_t)GETPAGESIZE(); # endif /* It is acceptable to fake it. */ GC_page_size = HBLKSIZE; # else GC_page_size = (size_t)GETPAGESIZE(); # if !defined(CPPCHECK) if (0 == GC_page_size) ABORT("getpagesize failed"); # endif # endif #endif /* !ANY_MSWIN */ #ifdef SOFT_VDB { size_t pgsize; unsigned log_pgsize = 0; # if !defined(CPPCHECK) if (((GC_page_size - 1) & GC_page_size) != 0) { /* Not a power of two. */ ABORT("Invalid page size"); } # endif for (pgsize = GC_page_size; pgsize > 1; pgsize >>= 1) log_pgsize++; GC_log_pagesize = log_pgsize; } #endif } #ifdef EMBOX # include # include GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { pthread_t self = pthread_self(); void *stack_addr = thread_stack_get(self); /* TODO: Use `pthread_getattr_np`, `pthread_attr_getstack` alternatively. */ # ifdef STACK_GROWS_UP sb->mem_base = stack_addr; # else sb->mem_base = (ptr_t)stack_addr + thread_stack_get_size(self); # endif return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* EMBOX */ #ifdef OS2 GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { PTIB ptib; /*< thread information block */ PPIB ppib; if (DosGetInfoBlocks(&ptib, &ppib) != NO_ERROR) { WARN("DosGetInfoBlocks failed\n", 0); return GC_UNIMPLEMENTED; } sb->mem_base = ptib->tib_pstacklimit; return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* OS2 */ #ifdef SERENITY # include GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { uintptr_t base; size_t size; if (get_stack_bounds(&base, &size) < 0) { WARN("get_stack_bounds failed\n", 0); return GC_UNIMPLEMENTED; } sb->mem_base = base + size; return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* SERENITY */ #if defined(NEED_FIND_LIMIT) \ || (defined(UNIX_LIKE) && !defined(NO_DEBUGGING)) \ || (defined(USE_PROC_FOR_LIBRARIES) && defined(THREADS)) \ || (defined(WRAP_MARK_SOME) && defined(NO_SEH_AVAILABLE)) # include # ifdef USE_SEGV_SIGACT # ifndef OPENBSD static struct sigaction old_segv_act; # endif # ifdef USE_BUS_SIGACT static struct sigaction old_bus_act; # endif # else static GC_fault_handler_t old_segv_hand; # ifdef HAVE_SIGBUS static GC_fault_handler_t old_bus_hand; # endif # endif /* !USE_SEGV_SIGACT */ GC_INNER void GC_set_and_save_fault_handler(GC_fault_handler_t h) { # ifdef USE_SEGV_SIGACT struct sigaction act; act.sa_handler = h; # ifdef SIGACTION_FLAGS_NODEFER_HACK /* Was necessary for Solaris 2.3 and very temporary NetBSD bugs. */ act.sa_flags = SA_RESTART | SA_NODEFER; # else act.sa_flags = SA_RESTART; # endif (void)sigemptyset(&act.sa_mask); /* `act.sa_restorer` is deprecated and should not be initialized. */ # if defined(IRIX5) && defined(THREADS) /* * Older versions have a bug related to retrieving and setting * a handler at the same time. */ (void)sigaction(SIGSEGV, 0, &old_segv_act); (void)sigaction(SIGSEGV, &act, 0); # else (void)sigaction(SIGSEGV, &act, &old_segv_act); # ifdef USE_BUS_SIGACT /* * `pthreads` library does not exist under Irix 5.x, so we do not have * to worry of the multi-threaded case. */ (void)sigaction(SIGBUS, &act, &old_bus_act); # endif # endif /* !IRIX5 || !THREADS */ # else old_segv_hand = signal(SIGSEGV, h); # ifdef HAVE_SIGBUS old_bus_hand = signal(SIGBUS, h); # endif # endif /* !USE_SEGV_SIGACT */ # if defined(CPPCHECK) && defined(ADDRESS_SANITIZER) GC_noop1((word)(GC_funcptr_uint)(&__asan_default_options)); # endif } #endif /* NEED_FIND_LIMIT || UNIX_LIKE || WRAP_MARK_SOME */ #if defined(NEED_FIND_LIMIT) \ || (defined(USE_PROC_FOR_LIBRARIES) && defined(THREADS)) \ || (defined(WRAP_MARK_SOME) && defined(NO_SEH_AVAILABLE)) GC_INNER JMP_BUF GC_jmp_buf; STATIC void GC_fault_handler(int sig) { UNUSED_ARG(sig); LONGJMP(GC_jmp_buf, 1); } GC_INNER void GC_setup_temporary_fault_handler(void) { /* * Handler is process-wide, so this should only happen in one thread * at a time. */ GC_ASSERT(I_HOLD_LOCK()); GC_set_and_save_fault_handler(GC_fault_handler); } GC_INNER void GC_reset_fault_handler(void) { # ifdef USE_SEGV_SIGACT (void)sigaction(SIGSEGV, &old_segv_act, 0); # ifdef USE_BUS_SIGACT (void)sigaction(SIGBUS, &old_bus_act, 0); # endif # else (void)signal(SIGSEGV, old_segv_hand); # ifdef HAVE_SIGBUS (void)signal(SIGBUS, old_bus_hand); # endif # endif } #endif /* NEED_FIND_LIMIT || USE_PROC_FOR_LIBRARIES || WRAP_MARK_SOME */ #if defined(NEED_FIND_LIMIT) \ || (defined(USE_PROC_FOR_LIBRARIES) && defined(THREADS)) # define MIN_PAGE_SIZE 256 /*< smallest conceivable page size, in bytes */ /* * Return the first non-addressable location greater than `p` (if `up`) * or the smallest location `q` such that [`q`,`p`) is addressable (if * not `up`). We assume that `p` (if `up`) or `p - 1` (if not `up`) is * addressable. */ GC_ATTR_NO_SANITIZE_ADDR STATIC ptr_t GC_find_limit_with_bound(ptr_t p, GC_bool up, ptr_t bound) { /* * This is safer if `static`, since otherwise it may not be preserved * across the `longjmp`. Can safely be `static` since it is only called * with the allocator lock held. */ static volatile ptr_t result; GC_ASSERT(up ? ADDR(bound) >= MIN_PAGE_SIZE : ADDR(bound) <= ~(word)MIN_PAGE_SIZE); GC_ASSERT(I_HOLD_LOCK()); result = PTR_ALIGN_DOWN(p, MIN_PAGE_SIZE); GC_setup_temporary_fault_handler(); if (SETJMP(GC_jmp_buf) == 0) { for (;;) { if (up) { if (ADDR_GE(result, bound - MIN_PAGE_SIZE)) { result = bound; break; } /* * Notes: no overflow is expected; do not use compound assignment * with `volatile`-qualified left operand. */ result = result + MIN_PAGE_SIZE; } else { if (ADDR_GE(bound + MIN_PAGE_SIZE, result)) { /* * This is to compensate further result increment (we do not * modify `up` variable since it might be clobbered by `setjmp()` * otherwise). */ result = bound - MIN_PAGE_SIZE; break; } /* See the notes for the case when `up` is `TRUE`. */ result = result - MIN_PAGE_SIZE; } GC_noop1((word)(unsigned char)(*result)); } } GC_reset_fault_handler(); return up ? result : result + MIN_PAGE_SIZE; } void * GC_find_limit(void *p, int up) { ptr_t bound; # ifdef CHERI_PURECAP bound = (ptr_t)cheri_address_set(p, cheri_base_get(p) + (up ? cheri_length_get(p) : 0)); # else bound = up ? MAKE_CPTR(GC_WORD_MAX) : NULL; # endif return GC_find_limit_with_bound((ptr_t)p, (GC_bool)up, bound); } #endif /* NEED_FIND_LIMIT || USE_PROC_FOR_LIBRARIES */ #if defined(HPUX) && defined(IA64) # include # include GC_INNER ptr_t GC_get_register_stack_base(void) { struct pst_vm_status vm_status; int i = 0; while (pstat_getprocvm(&vm_status, sizeof(vm_status), 0, i++) == 1) { if (vm_status.pst_type == PS_RSESTACK) { return (ptr_t)vm_status.pst_vaddr; } } /* Old way to get the register stack bottom. */ GC_ASSERT(GC_stackbottom != NULL); return PTR_ALIGN_DOWN(GC_stackbottom - BACKING_STORE_DISPLACEMENT - 1, BACKING_STORE_ALIGNMENT); } #endif /* HPUX && IA64 */ #if defined(LINUX) && defined(IA64) # ifdef USE_LIBC_PRIVATES EXTERN_C_BEGIN # pragma weak __libc_ia64_register_backing_store_base extern ptr_t __libc_ia64_register_backing_store_base; EXTERN_C_END # endif GC_INNER ptr_t GC_get_register_stack_base(void) { ptr_t result; GC_ASSERT(I_HOLD_LOCK()); # ifdef USE_LIBC_PRIVATES { ptr_t *p_libc_ia64_register_backing_store_base = &__libc_ia64_register_backing_store_base; # ifdef CPPCHECK /* * Workaround a warning that the address of the global symbol * (which is a weak one) cannot be null. */ GC_noop1_ptr(&p_libc_ia64_register_backing_store_base); # endif if (p_libc_ia64_register_backing_store_base != NULL && __libc_ia64_register_backing_store_base != NULL) { /* * `glibc` 2.2.4 has a bug such that for dynamically linked * executables `__libc_ia64_register_backing_store_base` is * defined but uninitialized during constructor calls. * Hence we check for both nonzero address and value. */ return __libc_ia64_register_backing_store_base; } } # endif result = backing_store_base_from_proc(); if (0 == result) { /* This works better than a constant displacement heuristic. */ result = (ptr_t)GC_find_limit(GC_save_regs_in_stack(), FALSE); } return result; } #endif /* LINUX && IA64 */ #ifdef SPECIFIC_MAIN_STACKBOTTOM # ifdef HPUX # include # include static ptr_t os_main_stackbottom(void) { struct pst_vm_status vm_status; int i = 0; while (pstat_getprocvm(&vm_status, sizeof(vm_status), 0, i++) == 1) { if (vm_status.pst_type == PS_STACK) return (ptr_t)vm_status.pst_vaddr; } /* Old way to get the stack bottom. */ # ifdef STACK_GROWS_UP return (ptr_t)GC_find_limit(GC_approx_sp(), FALSE); # else return (ptr_t)GC_find_limit(GC_approx_sp(), TRUE /* `up` */); # endif } # elif defined(LINUX) # include /* Number of fields preceding `startstack` one in `/proc/self/stat` file. */ # define STAT_SKIP 27 # ifdef USE_LIBC_PRIVATES EXTERN_C_BEGIN # pragma weak __libc_stack_end extern ptr_t __libc_stack_end; EXTERN_C_END # endif static ptr_t os_main_stackbottom(void) { /* * We read the stack bottom value from `/proc/self/stat` file. * We do this using direct I/O system calls in order to avoid * calling `malloc` in case `REDIRECT_MALLOC` is defined. */ # define STAT_BUF_SIZE 4096 unsigned char stat_buf[STAT_BUF_SIZE]; int f; word addr; ssize_t i, buf_offset = 0, len; /* * First try the easy way. This should work for `glibc` 2.2. * This fails in a prelinked (`prelink` command) executable * since the correct value of `__libc_stack_end` never becomes * visible to us. The second test is a workaround for this. */ # ifdef USE_LIBC_PRIVATES ptr_t *p_libc_stack_end = &__libc_stack_end; # ifdef CPPCHECK GC_noop1_ptr(&p_libc_stack_end); # endif if (p_libc_stack_end != NULL && __libc_stack_end != NULL) { # ifdef IA64 /* * Some versions of `glibc` set the address 16 bytes too low * while the initialization code is running. */ if ((ADDR(__libc_stack_end) & 0xfff) + 0x10 < 0x1000) { return __libc_stack_end + 0x10; } else { /* It is not safe to add 16 bytes. Thus, fall back to using `/proc`. */ } # elif defined(SPARC) /* * Older versions of `glibc` for 64-bit SPARC do not set this * variable correctly, it gets set to either zero or one. */ if (ADDR(__libc_stack_end) != 1) return __libc_stack_end; # else return __libc_stack_end; # endif } # endif f = open("/proc/self/stat", O_RDONLY); if (-1 == f) ABORT_ARG1("Could not open /proc/self/stat", ": errno= %d", errno); len = GC_repeat_read(f, (char *)stat_buf, sizeof(stat_buf)); if (len < 0) ABORT_ARG1("Failed to read /proc/self/stat", ": errno= %d", errno); close(f); /* * Skip the required number of fields. This number is hopefully constant * across all Linux implementations. */ for (i = 0; i < STAT_SKIP; ++i) { while (buf_offset < len && isspace(stat_buf[buf_offset++])) { /* Empty. */ } while (buf_offset < len && !isspace(stat_buf[buf_offset++])) { /* Empty. */ } } /* Skip spaces. */ while (buf_offset < len && isspace(stat_buf[buf_offset])) { buf_offset++; } /* Find the end of the number and cut the buffer there. */ for (i = 0; buf_offset + i < len; i++) { if (!isdigit(stat_buf[buf_offset + i])) break; } if (buf_offset + i >= len) ABORT("Could not parse /proc/self/stat"); stat_buf[buf_offset + i] = '\0'; addr = (word)STRTOULL((char *)stat_buf + buf_offset, NULL, 10); if (addr < 0x100000 || addr % ALIGNMENT != 0) ABORT_ARG1("Absurd stack bottom value", ": 0x%lx", (unsigned long)addr); return MAKE_CPTR(addr); } # elif defined(QNX) static ptr_t os_main_stackbottom(void) { /* * TODO: This approach is not very exact but it works for the tests, * at least, unlike other available heuristics. */ return (ptr_t)__builtin_frame_address(0); } # elif defined(FREEBSD) # include /* * This uses an undocumented `sysctl` call, but at least one expert * believes it will stay. */ static ptr_t os_main_stackbottom(void) { int nm[2] = { CTL_KERN, KERN_USRSTACK }; ptr_t base; size_t len = sizeof(ptr_t); int r = sysctl(nm, 2, &base, &len, NULL, 0); if (r != 0) ABORT("Error getting main stack base"); return base; } # endif #endif /* SPECIFIC_MAIN_STACKBOTTOM */ #if defined(ECOS) || defined(NOSYS) GC_INNER ptr_t GC_get_main_stack_base(void) { return STACKBOTTOM; } # define GET_MAIN_STACKBASE_SPECIAL #elif defined(SYMBIAN) EXTERN_C_BEGIN extern int GC_get_main_symbian_stack_base(void); EXTERN_C_END GC_INNER ptr_t GC_get_main_stack_base(void) { return (ptr_t)GC_get_main_symbian_stack_base(); } # define GET_MAIN_STACKBASE_SPECIAL #elif defined(EMSCRIPTEN) # include GC_INNER ptr_t GC_get_main_stack_base(void) { return (ptr_t)emscripten_stack_get_base(); } # define GET_MAIN_STACKBASE_SPECIAL #elif !defined(ANY_MSWIN) && !defined(EMBOX) && !defined(OS2) \ && !(defined(OPENBSD) && defined(THREADS)) && !defined(SERENITY) \ && (!(defined(SOLARIS) && defined(THREADS)) || defined(_STRICT_STDC)) # if (defined(HAVE_PTHREAD_ATTR_GET_NP) || defined(HAVE_PTHREAD_GETATTR_NP)) \ && (defined(THREADS) || defined(USE_GET_STACKBASE_FOR_MAIN)) # include # ifdef HAVE_PTHREAD_NP_H # include /*< for `pthread_attr_get_np()` */ # endif # elif defined(DARWIN) && !defined(NO_PTHREAD_GET_STACKADDR_NP) /* * We could use `pthread_get_stackaddr_np` even in case of a single-threaded * collector build (there is no `-lpthread` option on Darwin). */ # include # undef STACKBOTTOM # define STACKBOTTOM (ptr_t) pthread_get_stackaddr_np(pthread_self()) # endif GC_INNER ptr_t GC_get_main_stack_base(void) { ptr_t result; # if (defined(HAVE_PTHREAD_ATTR_GET_NP) || defined(HAVE_PTHREAD_GETATTR_NP)) \ && (defined(USE_GET_STACKBASE_FOR_MAIN) \ || (defined(THREADS) && !defined(REDIRECT_MALLOC))) pthread_attr_t attr; void *stackaddr; size_t size; # ifdef HAVE_PTHREAD_ATTR_GET_NP if (pthread_attr_init(&attr) == 0 && (pthread_attr_get_np(pthread_self(), &attr) == 0 ? TRUE : (pthread_attr_destroy(&attr), FALSE))) # else /* HAVE_PTHREAD_GETATTR_NP */ if (pthread_getattr_np(pthread_self(), &attr) == 0) # endif { if (pthread_attr_getstack(&attr, &stackaddr, &size) == 0 && stackaddr != NULL) { (void)pthread_attr_destroy(&attr); # ifndef STACK_GROWS_UP stackaddr = (char *)stackaddr + size; # endif return (ptr_t)stackaddr; } (void)pthread_attr_destroy(&attr); } WARN("pthread_getattr_np or pthread_attr_getstack failed" " for main thread\n", 0); # endif # ifdef STACKBOTTOM result = STACKBOTTOM; # else # ifdef HEURISTIC1 # define STACKBOTTOM_ALIGNMENT_M1 ((word)STACK_GRAN - 1) # ifdef STACK_GROWS_UP result = PTR_ALIGN_DOWN(GC_approx_sp(), STACKBOTTOM_ALIGNMENT_M1 + 1); # else result = PTR_ALIGN_UP(GC_approx_sp(), STACKBOTTOM_ALIGNMENT_M1 + 1); # endif # elif defined(SPECIFIC_MAIN_STACKBOTTOM) result = os_main_stackbottom(); # elif defined(HEURISTIC2) { ptr_t sp = GC_approx_sp(); # ifdef STACK_GROWS_UP result = (ptr_t)GC_find_limit(sp, FALSE); # else result = (ptr_t)GC_find_limit(sp, TRUE /* `up` */); # endif # if defined(HEURISTIC2_LIMIT) && !defined(CPPCHECK) if (HOTTER_THAN(HEURISTIC2_LIMIT, result) && HOTTER_THAN(sp, HEURISTIC2_LIMIT)) result = HEURISTIC2_LIMIT; # endif } # elif defined(STACK_NOT_SCANNED) || defined(CPPCHECK) result = NULL; # else # error None of HEURISTIC* and *STACKBOTTOM defined! # endif # if !defined(STACK_GROWS_UP) && !defined(CPPCHECK) if (NULL == result) result = MAKE_CPTR((GC_signed_word)(-sizeof(ptr_t))); # endif # endif # if !defined(CPPCHECK) GC_ASSERT(HOTTER_THAN(GC_approx_sp(), result)); # endif return result; } # define GET_MAIN_STACKBASE_SPECIAL #endif /* !ANY_MSWIN && !EMBOX && !OS2 && !SERENITY */ #if (defined(HAVE_PTHREAD_ATTR_GET_NP) || defined(HAVE_PTHREAD_GETATTR_NP)) \ && defined(THREADS) && !defined(HAVE_GET_STACK_BASE) # include # ifdef HAVE_PTHREAD_NP_H # include # endif GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *b) { pthread_attr_t attr; size_t size; # ifdef HAVE_PTHREAD_ATTR_GET_NP if (pthread_attr_init(&attr) != 0) ABORT("pthread_attr_init failed"); if (pthread_attr_get_np(pthread_self(), &attr) != 0) { WARN("pthread_attr_get_np failed\n", 0); (void)pthread_attr_destroy(&attr); return GC_UNIMPLEMENTED; } # else /* HAVE_PTHREAD_GETATTR_NP */ if (pthread_getattr_np(pthread_self(), &attr) != 0) { WARN("pthread_getattr_np failed\n", 0); return GC_UNIMPLEMENTED; } # endif if (pthread_attr_getstack(&attr, &b->mem_base, &size) != 0) { ABORT("pthread_attr_getstack failed"); } (void)pthread_attr_destroy(&attr); # ifndef STACK_GROWS_UP b->mem_base = (char *)b->mem_base + size; # endif # ifdef IA64 /* * We could try `backing_store_base_from_proc`, but that is safe only * if no mappings are being asynchronously created. Subtracting the size * from the stack base does not work for at least the main thread. */ LOCK(); { IF_CANCEL(int cancel_state;) ptr_t bsp; ptr_t next_stack; DISABLE_CANCEL(cancel_state); bsp = GC_save_regs_in_stack(); next_stack = GC_greatest_stack_base_below(bsp); if (NULL == next_stack) { b->reg_base = GC_find_limit(bsp, FALSE); } else { /* * Avoid walking backwards into preceding memory stack and * growing it. */ b->reg_base = GC_find_limit_with_bound(bsp, FALSE, next_stack); } RESTORE_CANCEL(cancel_state); } UNLOCK(); # elif defined(E2K) b->reg_base = NULL; # endif return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* THREADS && (HAVE_PTHREAD_ATTR_GET_NP || HAVE_PTHREAD_GETATTR_NP) */ #if defined(DARWIN) && defined(THREADS) \ && !defined(NO_PTHREAD_GET_STACKADDR_NP) # include GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *b) { /* * `pthread_get_stackaddr_np()` should return stack bottom (highest * stack address plus 1). */ b->mem_base = pthread_get_stackaddr_np(pthread_self()); GC_ASSERT(HOTTER_THAN(GC_approx_sp(), (ptr_t)b->mem_base)); return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* DARWIN && THREADS && !NO_PTHREAD_GET_STACKADDR_NP */ #if defined(OPENBSD) && defined(THREADS) # include # include # include GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { stack_t stack; /* Find the stack using `pthread_stackseg_np()`. */ if (pthread_stackseg_np(pthread_self(), &stack)) ABORT("pthread_stackseg_np(self) failed"); sb->mem_base = stack.ss_sp; return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* OPENBSD && THREADS */ #if defined(SOLARIS) && defined(THREADS) && !defined(_STRICT_STDC) # include # include /* * These variables are used to cache `ss_sp` value for the primordial * thread (it is better not to call `thr_stksegment()` twice for this * thread - see JDK bug #4352906). * Note: `stackbase_main_self` set to zero means `stackbase_main_ss_sp` * value is unset. */ static pthread_t stackbase_main_self = 0; static void *stackbase_main_ss_sp = NULL; # ifdef CAN_HANDLE_FORK GC_INNER void GC_stackbase_info_update_after_fork(void) { if (stackbase_main_self == GC_parent_pthread_self) { /* The primordial thread has forked the process. */ stackbase_main_self = pthread_self(); } else { stackbase_main_self = 0; } } # endif GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *b) { stack_t s; pthread_t self = pthread_self(); if (self == stackbase_main_self) { /* * If the client calls `GC_get_stack_base()` from the main thread, * then just return the cached value. */ b->mem_base = stackbase_main_ss_sp; GC_ASSERT(b->mem_base != NULL); return GC_SUCCESS; } if (thr_stksegment(&s)) { /* * According to the manual, the only failure error code returned is * `EAGAIN` meaning "the information is not available due to the thread * is not yet completely initialized or it is an internal thread" - this * should not happen here. */ ABORT("thr_stksegment failed"); } /* `s.ss_sp` holds the pointer to the stack bottom. */ GC_ASSERT(HOTTER_THAN(GC_approx_sp(), (ptr_t)s.ss_sp)); if (!stackbase_main_self && thr_main() != 0) { /* * Cache the stack bottom pointer for the primordial thread * (this is done during `GC_init`, so there is no race). */ stackbase_main_ss_sp = s.ss_sp; stackbase_main_self = self; } b->mem_base = s.ss_sp; return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* SOLARIS && THREADS */ #if defined(RTEMS) && defined(THREADS) GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *sb) { sb->mem_base = rtems_get_stack_bottom(); return GC_SUCCESS; } # define HAVE_GET_STACK_BASE #endif /* RTEMS && THREADS */ #ifndef HAVE_GET_STACK_BASE # ifdef NEED_FIND_LIMIT GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *b) { IF_CANCEL(int cancel_state;) /* * Note: using the `GC_find_limit` variant is risky; in the IA-64 case, * e.g., there is no guard page between the stack of one thread and the * register backing store of the next; thus this is likely to identify way * too large a "stack" and thus at least result in disastrous performance. */ /* TODO: Implement better strategies here. */ LOCK(); /* TODO: `DISABLE_CANCEL` may be unnecessary? */ DISABLE_CANCEL(cancel_state); # ifdef STACK_GROWS_UP b->mem_base = GC_find_limit(GC_approx_sp(), FALSE); # else b->mem_base = GC_find_limit(GC_approx_sp(), TRUE /* `up` */); # endif # ifdef IA64 b->reg_base = GC_find_limit(GC_save_regs_in_stack(), FALSE); # elif defined(E2K) b->reg_base = NULL; # endif RESTORE_CANCEL(cancel_state); UNLOCK(); return GC_SUCCESS; } # else /* !NEED_FIND_LIMIT */ GC_API int GC_CALL GC_get_stack_base(struct GC_stack_base *b) { # if defined(GET_MAIN_STACKBASE_SPECIAL) && !defined(THREADS) \ && !defined(IA64) b->mem_base = GC_get_main_stack_base(); return GC_SUCCESS; # else UNUSED_ARG(b); return GC_UNIMPLEMENTED; # endif } # endif #endif /* !HAVE_GET_STACK_BASE */ #ifndef GET_MAIN_STACKBASE_SPECIAL GC_INNER ptr_t GC_get_main_stack_base(void) { /* Default implementation. */ struct GC_stack_base sb; if (GC_get_stack_base(&sb) != GC_SUCCESS) ABORT("GC_get_stack_base failed"); GC_ASSERT(HOTTER_THAN(GC_approx_sp(), (ptr_t)sb.mem_base)); return (ptr_t)sb.mem_base; } #endif /* !GET_MAIN_STACKBASE_SPECIAL */ /* * Register static data segment(s) as roots. If more data segments are * added later, then they need to be registered at that point (as we do * with SunOS dynamic loading), or `GC_mark_roots` needs to check for them. */ #ifdef ANY_MSWIN # if defined(GWW_VDB) # ifndef MEM_WRITE_WATCH # define MEM_WRITE_WATCH 0x200000 # endif # ifndef WRITE_WATCH_FLAG_RESET # define WRITE_WATCH_FLAG_RESET 1 # endif /* * Since we cannot easily check whether `ULONG_PTR` and `SIZE_T` are * defined in Win32 `basetsd.h` file, we define own `ULONG_PTR`. */ # define GC_ULONG_PTR word typedef UINT(WINAPI *GetWriteWatch_type)(DWORD, PVOID, GC_ULONG_PTR /* `SIZE_T` */, PVOID *, GC_ULONG_PTR *, PULONG); static FARPROC GetWriteWatch_func; static DWORD GetWriteWatch_alloc_flag; # define GC_GWW_AVAILABLE() (GetWriteWatch_func != 0) static void detect_GetWriteWatch(void) { static GC_bool done; HMODULE hK32; if (done) return; # if defined(MPROTECT_VDB) { char *str = GETENV("GC_USE_GETWRITEWATCH"); # if defined(GC_PREFER_MPROTECT_VDB) if (NULL == str || (*str == '0' && *(str + 1) == '\0')) { /* * `GC_USE_GETWRITEWATCH` environment variable is unset or set to "0". * Falling back to `MPROTECT_VDB` strategy. */ done = TRUE; /* This should work as if `GWW_VDB` macro is not defined. */ return; } # else if (str != NULL && *str == '0' && *(str + 1) == '\0') { /* * `GC_USE_GETWRITEWATCH` environment variable is set "0". * Falling back to `MPROTECT_VDB` strategy. */ done = TRUE; return; } # endif } # endif # if defined(MSWINRT_FLAVOR) && defined(FUNCPTR_IS_DATAPTR) { MEMORY_BASIC_INFORMATION memInfo; SIZE_T result = VirtualQuery(CAST_THRU_UINTPTR(void *, GetProcAddress), &memInfo, sizeof(memInfo)); if (result != sizeof(memInfo)) ABORT("Weird VirtualQuery result"); hK32 = (HMODULE)memInfo.AllocationBase; } # else hK32 = GetModuleHandle(TEXT("kernel32.dll")); # endif if (hK32 != (HMODULE)0 && (GetWriteWatch_func = GetProcAddress(hK32, "GetWriteWatch")) != 0) { void *page; GC_ASSERT(GC_page_size != 0); /* * Also check whether `VirtualAlloc()` accepts `MEM_WRITE_WATCH`, * as some versions of `kernel32.dll` library have one but not the other, * making the feature completely broken. */ page = VirtualAlloc(NULL, GC_page_size, MEM_WRITE_WATCH | MEM_RESERVE, PAGE_READWRITE); if (page != NULL) { PVOID pages[16]; GC_ULONG_PTR count = sizeof(pages) / sizeof(PVOID); DWORD page_size; /* * Check that it actually works. In spite of some documentation * it actually seems to exist on Win2K. * This test may be unnecessary, but... */ if ((*(GetWriteWatch_type)(GC_funcptr_uint)GetWriteWatch_func)( WRITE_WATCH_FLAG_RESET, page, GC_page_size, pages, &count, &page_size) != 0) { /* `GetWriteWatch()` always fails. */ GetWriteWatch_func = 0; } else { GetWriteWatch_alloc_flag = MEM_WRITE_WATCH; } VirtualFree(page, 0 /* `dwSize` */, MEM_RELEASE); } else { /* `GetWriteWatch` will be useless. */ GetWriteWatch_func = 0; } } done = TRUE; } # else # define GetWriteWatch_alloc_flag 0 # endif /* !GWW_VDB */ # ifdef MSWIN32 /* * Unfortunately, we have to handle win32s very differently from Windows NT, * since `VirtualQuery()` has very different semantics. In particular, * under win32s a `VirtualQuery()` call on an unmapped page returns * an invalid result. Under Windows NT, `GC_register_data_segments()` is * a no-op and all real work is done by `GC_register_dynamic_libraries()`. * Under win32s, we cannot find the data segments associated with DLL files. * We register the main data segment here. */ GC_INNER GC_bool GC_no_win32_dlls = FALSE; GC_INNER GC_bool GC_wnt = FALSE; GC_INNER void GC_init_win32(void) { # if defined(_WIN64) || (defined(_MSC_VER) && _MSC_VER >= 1800) /* * MS Visual Studio 2013 deprecates `GetVersion`, but on the other hand * it cannot be used to target pre-Win2K. */ GC_wnt = TRUE; # else /* * Set `GC_wnt`. If we are running under win32s, assume that no DLL file * will be loaded. I doubt anyone still runs win32s, but... */ DWORD v = GetVersion(); GC_wnt = !(v & (DWORD)0x80000000UL); GC_no_win32_dlls |= ((!GC_wnt) && (v & 0xff) <= 3); # endif # ifdef USE_MUNMAP if (GC_no_win32_dlls) { /* * Turn off unmapping for safety (since may not work well with * `GlobalAlloc()`). */ GC_unmap_threshold = 0; } # endif } /* * Return the smallest address `p` such that `VirtualQuery()` returns * correct results for all addresses between `p` and `start`. * Assumes `VirtualQuery()` returns correct information for `start`. */ STATIC ptr_t GC_least_described_address(ptr_t start) { ptr_t limit = (ptr_t)GC_sysinfo.lpMinimumApplicationAddress; ptr_t p = PTR_ALIGN_DOWN(start, GC_page_size); GC_ASSERT(GC_page_size != 0); for (;;) { MEMORY_BASIC_INFORMATION buf; size_t result; ptr_t q; if (UNLIKELY(ADDR(p) <= (word)GC_page_size)) break; /*< avoid underflow */ q = p - GC_page_size; if (ADDR_LT(q, limit)) break; result = VirtualQuery((LPVOID)q, &buf, sizeof(buf)); if (result != sizeof(buf) || 0 == buf.AllocationBase) break; p = (ptr_t)buf.AllocationBase; } return p; } STATIC void GC_register_root_section(ptr_t static_root) { ptr_t p, base, limit; GC_ASSERT(I_HOLD_LOCK()); if (!GC_no_win32_dlls) return; p = GC_least_described_address(static_root); base = limit = p; while (ADDR_LT(p, (ptr_t)GC_sysinfo.lpMaximumApplicationAddress)) { MEMORY_BASIC_INFORMATION buf; size_t result = VirtualQuery((LPVOID)p, &buf, sizeof(buf)); if (result != sizeof(buf) || 0 == buf.AllocationBase || GC_is_heap_base(buf.AllocationBase)) break; if (ADDR(p) > GC_WORD_MAX - buf.RegionSize) { /* Avoid overflow. */ break; } if (buf.State == MEM_COMMIT && is_writable(buf.Protect)) { if (p != limit) { if (base != limit) GC_add_roots_inner(base, limit, FALSE); base = p; } limit = p + buf.RegionSize; } p += buf.RegionSize; } if (base != limit) GC_add_roots_inner(base, limit, FALSE); } # endif /* MSWIN32 */ # if defined(USE_WINALLOC) && !defined(REDIRECT_MALLOC) /* * We maintain a linked list of `AllocationBase` values (that we know) * correspond to `malloc` heap sections. Currently this is only called * during a collection. But there is some hope that for long-running * programs we will eventually see most heap sections. * * In the long run, it would be more reliable to occasionally walk * the `malloc` heap with `HeapWalk()` on the default heap. * But that apparently works only for NT-based Windows. */ /* Note: initialized to approximate largest root size. */ STATIC size_t GC_max_root_size = 100000; /* In the long run, a better data structure would also be nice... */ STATIC struct GC_malloc_heap_list { void *allocation_base; struct GC_malloc_heap_list *next; } *GC_malloc_heap_l = 0; /* * Is `p` the base of one of the `malloc` heap sections we already * know about? */ STATIC GC_bool GC_is_malloc_heap_base(const void *p) { struct GC_malloc_heap_list *q; for (q = GC_malloc_heap_l; q != NULL; q = q->next) { if (q->allocation_base == p) return TRUE; } return FALSE; } STATIC void * GC_get_allocation_base(void *p) { MEMORY_BASIC_INFORMATION buf; size_t result = VirtualQuery(p, &buf, sizeof(buf)); if (result != sizeof(buf)) { ABORT("Weird VirtualQuery result"); } return buf.AllocationBase; } GC_INNER void GC_add_current_malloc_heap(void) { struct GC_malloc_heap_list *new_l = (struct GC_malloc_heap_list *)malloc( sizeof(struct GC_malloc_heap_list)); void *candidate; if (NULL == new_l) return; /* Explicitly set to suppress "maybe-uninitialized" gcc warning. */ new_l->allocation_base = NULL; candidate = GC_get_allocation_base(new_l); if (GC_is_malloc_heap_base(candidate)) { /* Try a little harder to find `malloc` heap. */ size_t req_size = 10000; do { void *p = malloc(req_size); if (NULL == p) { free(new_l); return; } candidate = GC_get_allocation_base(p); free(p); req_size *= 2; } while (GC_is_malloc_heap_base(candidate) && req_size < GC_max_root_size / 10 && req_size < 500000); if (GC_is_malloc_heap_base(candidate)) { free(new_l); return; } } GC_COND_LOG_PRINTF("Found new system malloc AllocationBase at %p\n", candidate); new_l->allocation_base = candidate; new_l->next = GC_malloc_heap_l; GC_malloc_heap_l = new_l; } /* * Free all the linked list nodes. Could be invoked at process exit * to avoid memory leak complains of a dynamic code analysis tool. */ STATIC void GC_free_malloc_heap_list(void) { struct GC_malloc_heap_list *q = GC_malloc_heap_l; GC_malloc_heap_l = NULL; while (q != NULL) { struct GC_malloc_heap_list *next = q->next; free(q); q = next; } } # endif /* USE_WINALLOC && !REDIRECT_MALLOC */ GC_INNER GC_bool GC_is_heap_base(const void *p) { size_t i; # if defined(USE_WINALLOC) && !defined(REDIRECT_MALLOC) if (GC_root_size > GC_max_root_size) GC_max_root_size = GC_root_size; if (GC_is_malloc_heap_base(p)) return TRUE; # endif for (i = 0; i < GC_n_heap_bases; i++) { if (GC_heap_bases[i] == p) return TRUE; } return FALSE; } GC_INNER void GC_register_data_segments(void) { # ifdef MSWIN32 /* Note: any other GC global variable would fit too. */ GC_register_root_section((ptr_t)&GC_pages_executable); # endif } #endif /* ANY_MSWIN */ #ifdef DATASTART_USES_XGETDATASTART # ifdef CHERI_PURECAP # include /* * The CheriBSD LLVM compiler declares `etext`, `edata` and `end` as * typeless variables. If the collector library is statically linked * with the executable, these capabilities are compiled with the * read-only permissions and bounds that span the `.data` and `.bss` * sections. If the collector is compiled as a shared library, these * symbols are compiled with zero bounds and cannot be dereferenced; * instead, the read-only capability returned by the loader is used. */ struct scan_bounds_s { word start_addr; word end_addr; ptr_t ld_cap; }; static int ld_cap_search(struct dl_phdr_info *info, size_t size, void *cd) { struct scan_bounds_s *region = (struct scan_bounds_s *)cd; ptr_t load_ptr = (ptr_t)info->dlpi_addr; UNUSED_ARG(size); if (!SPANNING_CAPABILITY(load_ptr, region->start_addr, region->end_addr)) return 0; region->ld_cap = (ptr_t)cheri_bounds_set( cheri_address_set(load_ptr, region->start_addr), region->end_addr - region->start_addr); return 1; /*< stop */ } static ptr_t derive_cap_from_ldr(ptr_t range_start, ptr_t range_end) { word scan_start = ADDR(range_start); word scan_end = ADDR(range_end); struct scan_bounds_s region; /* If symbols already span the required range, return one of them. */ if (SPANNING_CAPABILITY(range_start, scan_start, scan_end)) return range_start; if (SPANNING_CAPABILITY(range_end, scan_start, scan_end)) return range_end; /* * Fall-back option: derive `.data` plus `.bss` end pointer from the * read-only capability provided by loader. */ region.start_addr = scan_start; region.end_addr = scan_end; region.ld_cap = NULL; /*< prevent a compiler warning */ if (!dl_iterate_phdr(ld_cap_search, ®ion)) ABORT("Cannot find static roots for capability system"); GC_ASSERT(region.ld_cap != NULL); return region.ld_cap; } # endif /* CHERI_PURECAP */ GC_INNER ptr_t GC_SysVGetDataStart(size_t max_page_size, ptr_t etext_ptr) { volatile ptr_t result; GC_ASSERT(max_page_size % ALIGNMENT == 0); result = PTR_ALIGN_UP(etext_ptr, ALIGNMENT); # ifdef CHERI_PURECAP result = derive_cap_from_ldr(result, DATAEND); # endif GC_setup_temporary_fault_handler(); if (SETJMP(GC_jmp_buf) == 0) { /* * Note that this is not equivalent to just adding `max_page_size` to * `etext_ptr` because the latter is not guaranteed to be multiple of * the page size. */ ptr_t next_page = PTR_ALIGN_UP(result, max_page_size); # ifdef FREEBSD /* * It is unclear whether this should be identical to the below, or * whether it should apply to non-x86 architectures. For now we * do not assume that there is always an empty page after `etext`. * But in some cases there actually seems to be slightly more. * It also deals with holes between read-only and writable data. * * Try reading at the address. This should happen before there is * another thread. */ for (; ADDR_LT(next_page, DATAEND); next_page += max_page_size) { GC_noop1((word)(*(volatile unsigned char *)next_page)); } # else result = next_page + (ADDR(result) & ((word)max_page_size - 1)); /* Try writing to the address. */ { # ifdef AO_HAVE_fetch_and_add volatile AO_t zero = 0; (void)AO_fetch_and_add((volatile AO_t *)result, zero); # else /* Fall back to non-atomic fetch-and-store. */ char v = *result; # ifdef CPPCHECK GC_noop1_ptr(&v); # endif *result = v; # endif } # endif GC_reset_fault_handler(); } else { GC_reset_fault_handler(); /* * We got here via a `longjmp`. The address is not readable. * This is known to happen under Solaris 2.4 with gcc, which places * string constants in the `text` segment, but after `etext`. * Use plan B. Note that we now know there is a gap between `text` * and `data` segments, so plan A brought us something. */ # ifdef CHERI_PURECAP result = (ptr_t)GC_find_limit(cheri_address_set(result, ADDR(DATAEND)), FALSE); # else result = (ptr_t)GC_find_limit(DATAEND, FALSE); # endif } return (ptr_t)CAST_AWAY_VOLATILE_PVOID(result); } #endif /* DATASTART_USES_XGETDATASTART */ #if defined(OS2) GC_INNER void GC_register_data_segments(void) { PTIB ptib; PPIB ppib; HMODULE module_handle; # define PBUFSIZ 512 UCHAR path[PBUFSIZ]; FILE *myexefile; struct exe_hdr hdrdos; /*< MSDOS header */ struct e32_exe hdr386; /*< real header for my executable */ struct o32_obj seg; /*< current segment */ int nsegs; # if defined(CPPCHECK) hdrdos.padding[0] = 0; /*< to prevent "field unused" warnings */ hdr386.exe_format_level = 0; hdr386.os = 0; hdr386.padding1[0] = 0; hdr386.padding2[0] = 0; seg.pagemap = 0; seg.mapsize = 0; seg.reserved = 0; # endif if (DosGetInfoBlocks(&ptib, &ppib) != NO_ERROR) { ABORT("DosGetInfoBlocks failed"); } module_handle = ppib->pib_hmte; if (DosQueryModuleName(module_handle, PBUFSIZ, path) != NO_ERROR) { ABORT("DosQueryModuleName failed"); } myexefile = fopen(path, "rb"); if (myexefile == 0) { ABORT_ARG1("Failed to open executable", ": %s", path); } if (fread((char *)&hdrdos, 1, sizeof(hdrdos), myexefile) < sizeof(hdrdos)) { ABORT_ARG1("Could not read MSDOS header", " from: %s", path); } if (E_MAGIC(hdrdos) != EMAGIC) { ABORT_ARG1("Bad DOS magic number", " in file: %s", path); } if (fseek(myexefile, E_LFANEW(hdrdos), SEEK_SET) != 0) { ABORT_ARG1("Bad DOS magic number", " in file: %s", path); } if (fread((char *)&hdr386, 1, sizeof(hdr386), myexefile) < sizeof(hdr386)) { ABORT_ARG1("Could not read OS/2 header", " from: %s", path); } if (E32_MAGIC1(hdr386) != E32MAGIC1 || E32_MAGIC2(hdr386) != E32MAGIC2) { ABORT_ARG1("Bad OS/2 magic number", " in file: %s", path); } if (E32_BORDER(hdr386) != E32LEBO || E32_WORDER(hdr386) != E32LEWO) { ABORT_ARG1("Bad byte order in executable", " file: %s", path); } if (E32_CPU(hdr386) == E32CPU286) { ABORT_ARG1("GC cannot handle 80286 executables", ": %s", path); } if (fseek(myexefile, E_LFANEW(hdrdos) + E32_OBJTAB(hdr386), SEEK_SET) != 0) { ABORT_ARG1("Seek to object table failed", " in file: %s", path); } for (nsegs = E32_OBJCNT(hdr386); nsegs > 0; nsegs--) { int flags; if (fread((char *)&seg, 1, sizeof(seg), myexefile) < sizeof(seg)) { ABORT_ARG1("Could not read obj table entry", " from file: %s", path); } flags = O32_FLAGS(seg); if (!(flags & OBJWRITE)) continue; if (!(flags & OBJREAD)) continue; if (flags & OBJINVALID) { GC_err_printf("Object with invalid pages?\n"); continue; } GC_add_roots_inner((ptr_t)O32_BASE(seg), (ptr_t)(O32_BASE(seg) + O32_SIZE(seg)), FALSE); } (void)fclose(myexefile); } #elif defined(OPENBSD) GC_INNER void GC_register_data_segments(void) { /* * Depending on arch alignment, there can be multiple holes between * `DATASTART` and `DATAEND`. Scan in `DATASTART` .. `DATAEND` and * register each region. */ ptr_t region_start = DATASTART; GC_ASSERT(I_HOLD_LOCK()); if (ADDR(region_start) - 1U >= ADDR(DATAEND)) ABORT_ARG2("Wrong DATASTART/END pair", ": %p .. %p", (void *)region_start, (void *)DATAEND); for (;;) { ptr_t region_end = GC_find_limit_with_bound(region_start, TRUE, DATAEND); GC_add_roots_inner(region_start, region_end, FALSE); if (ADDR_GE(region_end, DATAEND)) break; region_start = GC_skip_hole_openbsd(region_end, DATAEND); } } #elif !defined(ANY_MSWIN) GC_INNER void GC_register_data_segments(void) { GC_ASSERT(I_HOLD_LOCK()); # if !defined(DYNAMIC_LOADING) && defined(GC_DONT_REGISTER_MAIN_STATIC_DATA) /* * Avoid even referencing `DATASTART` and `DATAEND` as they are * unnecessary and cause linker errors when bitcode is enabled. * `GC_register_data_segments` is not called anyway. */ # elif defined(DYNAMIC_LOADING) && (defined(DARWIN) || defined(HAIKU)) /* No-op. `GC_register_main_static_data()` always returns `FALSE`. */ # elif defined(REDIRECT_MALLOC) && defined(SOLARIS) && defined(THREADS) /* * As of Solaris 2.3, the Solaris threads implementation allocates * the data structure for the initial thread with `sbrk` at the * process startup. It needs to be scanned, so that we do not lose * some `malloc`-allocated data structures hanging from it. * We are on thin ice here... */ GC_ASSERT(DATASTART); { ptr_t p = (ptr_t)sbrk(0); if (ADDR_LT(DATASTART, p)) GC_add_roots_inner(DATASTART, p, FALSE); } # else /* * Note: subtract one is to also check for `NULL` without a compiler * warning. */ if (ADDR(DATASTART) - 1U >= ADDR(DATAEND)) { ABORT_ARG2("Wrong DATASTART/END pair", ": %p .. %p", (void *)DATASTART, (void *)DATAEND); } GC_add_roots_inner(DATASTART, DATAEND, FALSE); # ifdef GC_HAVE_DATAREGION2 if (ADDR(DATASTART2) - 1U >= ADDR(DATAEND2)) ABORT_ARG2("Wrong DATASTART/END2 pair", ": %p .. %p", (void *)DATASTART2, (void *)DATAEND2); GC_add_roots_inner(DATASTART2, DATAEND2, FALSE); # endif # endif /* * Dynamic libraries are added at every collection, since they * may change. */ } #endif /* !ANY_MSWIN && !OPENBSD && !OS2 */ /* Auxiliary routines for obtaining memory from OS. */ #ifdef NEED_UNIX_GET_MEM # define SBRK_ARG_T ptrdiff_t # if defined(MMAP_SUPPORTED) # ifdef USE_MMAP_FIXED /* * Seems to yield better performance on Solaris 2, but can be unreliable * if something is already mapped at the address. */ # define GC_MMAP_FLAGS MAP_FIXED | MAP_PRIVATE # else # define GC_MMAP_FLAGS MAP_PRIVATE # endif # ifdef USE_MMAP_ANON # define zero_fd -1 # if defined(MAP_ANONYMOUS) && !defined(CPPCHECK) # define OPT_MAP_ANON MAP_ANONYMOUS # else # define OPT_MAP_ANON MAP_ANON # endif # else static int zero_fd = -1; # define OPT_MAP_ANON 0 # endif # ifndef MSWIN_XBOX1 # if defined(SYMBIAN) && !defined(USE_MMAP_ANON) EXTERN_C_BEGIN extern char *GC_get_private_path_and_zero_file(void); EXTERN_C_END # endif STATIC void * GC_unix_mmap_get_mem(size_t bytes) { void *result; static word last_addr = HEAP_START; # ifndef USE_MMAP_ANON static GC_bool initialized = FALSE; if (UNLIKELY(!initialized)) { # ifdef SYMBIAN char *path = GC_get_private_path_and_zero_file(); if (path != NULL) { zero_fd = open(path, O_RDWR | O_CREAT, 0644); free(path); } # else zero_fd = open("/dev/zero", O_RDONLY); # endif if (zero_fd == -1) ABORT("Could not open /dev/zero"); if (fcntl(zero_fd, F_SETFD, FD_CLOEXEC) == -1) WARN("Could not set FD_CLOEXEC for /dev/zero\n", 0); initialized = TRUE; } # endif GC_ASSERT(GC_page_size != 0); if (bytes & (GC_page_size - 1)) ABORT("Bad GET_MEM arg"); /* * Note: it is essential for CHERI to have only address part in * `last_addr` without metadata (thus the variable is of `word` type * intentionally), otherwise `mmap()` fails setting `errno` to `EPROT`. */ result = mmap(MAKE_CPTR(last_addr), bytes, (PROT_READ | PROT_WRITE) | (GC_pages_executable ? PROT_EXEC : 0), GC_MMAP_FLAGS | OPT_MAP_ANON, zero_fd, 0 /* `offset` */); # undef IGNORE_PAGES_EXECUTABLE if (UNLIKELY(MAP_FAILED == result)) { if (HEAP_START == last_addr && GC_pages_executable && (EACCES == errno || EPERM == errno)) ABORT("Cannot allocate executable pages"); return NULL; } # ifdef LINUX GC_ASSERT(ADDR(result) <= ~(word)(GC_page_size - 1) - bytes); /* The following `PTR_ALIGN_UP()` cannot overflow. */ # else if (UNLIKELY(ADDR(result) > ~(word)(GC_page_size - 1) - bytes)) { /* * Oops. We got the end of the address space. This is not usable * by arbitrary C code, since one-past-end pointers do not work, * so we discard it and try again. Leave the last page mapped, * so we cannot repeat. */ (void)munmap(result, ~(GC_page_size - 1) - (size_t)ADDR(result)); return GC_unix_mmap_get_mem(bytes); } # endif if ((ADDR(result) % HBLKSIZE) != 0) ABORT("Memory returned by mmap is not aligned to HBLKSIZE"); last_addr = ADDR(result) + bytes; GC_ASSERT((last_addr & (GC_page_size - 1)) == 0); return result; } # endif /* !MSWIN_XBOX1 */ # endif /* MMAP_SUPPORTED */ # if defined(USE_MMAP) GC_INNER void * GC_unix_get_mem(size_t bytes) { return GC_unix_mmap_get_mem(bytes); } # else /* !USE_MMAP */ STATIC void * GC_unix_sbrk_get_mem(size_t bytes) { void *result; # ifdef IRIX5 /* * Bare `sbrk()` is not thread-safe. Play by `malloc` rules. * The equivalent may be needed on other systems as well. */ __LOCK_MALLOC(); # endif { ptr_t cur_brk = (ptr_t)sbrk(0); SBRK_ARG_T lsbs = ADDR(cur_brk) & (GC_page_size - 1); GC_ASSERT(GC_page_size != 0); if (UNLIKELY((SBRK_ARG_T)bytes < 0)) { /* Value of `bytes` is too big. */ result = NULL; goto out; } if (lsbs != 0) { if ((ptr_t)sbrk((SBRK_ARG_T)GC_page_size - lsbs) == (ptr_t)(-1)) { result = NULL; goto out; } } # ifdef ADD_HEAP_GUARD_PAGES /* * This is useful for catching severe memory overwrite problems * that span heap sections. It should not otherwise be turned on. */ { ptr_t guard = (ptr_t)sbrk((SBRK_ARG_T)GC_page_size); if (mprotect(guard, GC_page_size, PROT_NONE) != 0) ABORT("ADD_HEAP_GUARD_PAGES: mprotect failed"); } # endif result = sbrk((SBRK_ARG_T)bytes); if (UNLIKELY(ADDR(result) == GC_WORD_MAX)) result = NULL; } out: # ifdef IRIX5 __UNLOCK_MALLOC(); # endif return result; } GC_INNER void * GC_unix_get_mem(size_t bytes) { # if defined(MMAP_SUPPORTED) /* By default, we try both `sbrk` and `mmap`, in that order. */ static GC_bool sbrk_failed = FALSE; void *result = NULL; if (GC_pages_executable) { /* * If the allocated memory should have the execute permission, * then `sbrk()` cannot be used. */ return GC_unix_mmap_get_mem(bytes); } if (!sbrk_failed) result = GC_unix_sbrk_get_mem(bytes); if (NULL == result) { sbrk_failed = TRUE; result = GC_unix_mmap_get_mem(bytes); if (NULL == result) { /* Try `sbrk()` again, in case `sbrk` memory became available. */ result = GC_unix_sbrk_get_mem(bytes); } } return result; # else /* !MMAP_SUPPORTED */ return GC_unix_sbrk_get_mem(bytes); # endif } # endif /* !USE_MMAP */ #endif /* NEED_UNIX_GET_MEM */ #if defined(OS2) GC_INNER void * GC_get_mem(size_t bytes) { void *result = NULL; int retry; GC_ASSERT(GC_page_size != 0); bytes = SIZET_SAT_ADD(bytes, GC_page_size); for (retry = 0;; retry++) { if (DosAllocMem(&result, bytes, (PAG_READ | PAG_WRITE | PAG_COMMIT) | (GC_pages_executable ? PAG_EXECUTE : 0)) == NO_ERROR && LIKELY(result != NULL)) break; /* * TODO: Unclear the purpose of the retry. (Probably, if `DosAllocMem` * returns memory at address zero, then just retry once.) */ if (retry >= 1) return NULL; } return HBLKPTR((ptr_t)result + GC_page_size - 1); } #elif defined(MSWIN_XBOX1) GC_INNER void * GC_get_mem(size_t bytes) { if (UNLIKELY(0 == bytes)) return NULL; return VirtualAlloc(NULL, bytes, MEM_COMMIT | MEM_TOP_DOWN, PAGE_READWRITE); } #elif defined(MSWINCE) GC_INNER void * GC_get_mem(size_t bytes) { void *result = NULL; /*< initialized to prevent a compiler warning */ size_t i; GC_ASSERT(GC_page_size != 0); bytes = ROUNDUP_PAGESIZE(bytes); /* Try to find reserved, uncommitted pages. */ for (i = 0; i < GC_n_heap_bases; i++) { if (((word)(-(GC_signed_word)GC_heap_lengths[i]) & (GC_sysinfo.dwAllocationGranularity - 1)) >= bytes) { result = GC_heap_bases[i] + GC_heap_lengths[i]; break; } } if (i == GC_n_heap_bases) { /* Reserve more pages. */ size_t res_bytes = SIZET_SAT_ADD(bytes, (size_t)GC_sysinfo.dwAllocationGranularity - 1) & ~((size_t)GC_sysinfo.dwAllocationGranularity - 1); /* * If we ever support `MPROTECT_VDB` here, we will probably need * to ensure that `res_bytes` is greater (strictly) than `bytes`, * so that `VirtualProtect()` never spans regions. It seems to be * fine for a `VirtualFree()` argument to span regions, so we * should be OK for now. */ result = VirtualAlloc(NULL, res_bytes, MEM_RESERVE | MEM_TOP_DOWN, GC_pages_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE); if (HBLKDISPL(result) != 0) { /* * If I read the documentation correctly, this can only happen * if `HBLKSIZE` is greater than 64 KB or not a power of 2. */ ABORT("Bad VirtualAlloc result"); } if (GC_n_heap_bases >= MAX_HEAP_SECTS) ABORT("Too many heap sections"); if (UNLIKELY(NULL == result)) return NULL; GC_heap_bases[GC_n_heap_bases] = (ptr_t)result; GC_heap_lengths[GC_n_heap_bases] = 0; GC_n_heap_bases++; } /* Commit pages. */ result = VirtualAlloc(result, bytes, MEM_COMMIT, GC_pages_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE); # undef IGNORE_PAGES_EXECUTABLE if (HBLKDISPL(result) != 0) ABORT("Bad VirtualAlloc result"); if (LIKELY(result != NULL)) GC_heap_lengths[i] += bytes; return result; } #elif defined(CYGWIN32) || defined(MSWIN32) # ifdef USE_GLOBAL_ALLOC # define GLOBAL_ALLOC_TEST 1 # else # define GLOBAL_ALLOC_TEST GC_no_win32_dlls # endif # if (defined(GC_USE_MEM_TOP_DOWN) && defined(USE_WINALLOC)) \ || defined(CPPCHECK) /* * Use `GC_USE_MEM_TOP_DOWN` for better 64-bit testing. * Otherwise all addresses tend to end up in the first 4 GB, hiding bugs. */ DWORD GC_mem_top_down = MEM_TOP_DOWN; # else # define GC_mem_top_down 0 # endif /* !GC_USE_MEM_TOP_DOWN */ GC_INNER void * GC_get_mem(size_t bytes) { void *result; # ifndef USE_WINALLOC result = GC_unix_get_mem(bytes); # else # if defined(MSWIN32) && !defined(MSWINRT_FLAVOR) if (GLOBAL_ALLOC_TEST) { /* * `VirtualAlloc()` does not like `PAGE_EXECUTE_READWRITE`. * There are also unconfirmed rumors of other problems, so we * dodge the issue. */ result = GlobalAlloc(0, SIZET_SAT_ADD(bytes, HBLKSIZE)); /* Align it at `HBLKSIZE` boundary (`NULL` value remains unchanged). */ result = PTR_ALIGN_UP((ptr_t)result, HBLKSIZE); } else # endif /* else */ { /* * `VirtualProtect()` only works on regions returned by a single * `VirtualAlloc()` call. Thus we allocate one extra page, which will * prevent merging of blocks in separate regions, and eliminate any * temptation to call `VirtualProtect()` on a range spanning regions. * This wastes a small amount of memory, and risks increased * fragmentation. But better alternatives would require effort. */ # ifdef MPROTECT_VDB /* * We cannot check for `GC_incremental` here (because * `GC_enable_incremental()` might be called some time later after * the collector initialization). */ # ifdef GWW_VDB # define VIRTUAL_ALLOC_PAD (GC_GWW_AVAILABLE() ? 0 : 1) # else # define VIRTUAL_ALLOC_PAD 1 # endif # else # define VIRTUAL_ALLOC_PAD 0 # endif /* * Pass `MEM_WRITE_WATCH` only if `GetWriteWatch`-based VDB is * enabled and `GetWriteWatch()` is available. Otherwise we waste * resources or possibly cause `VirtualAlloc()` to fail (observed * in Windows 2000 SP2). */ result = VirtualAlloc( NULL, SIZET_SAT_ADD(bytes, VIRTUAL_ALLOC_PAD), MEM_COMMIT | MEM_RESERVE | GetWriteWatch_alloc_flag | GC_mem_top_down, GC_pages_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE); # undef IGNORE_PAGES_EXECUTABLE } # endif if (HBLKDISPL(result) != 0) ABORT("Bad VirtualAlloc result"); if (GC_n_heap_bases >= MAX_HEAP_SECTS) ABORT("Too many heap sections"); if (LIKELY(result != NULL)) GC_heap_bases[GC_n_heap_bases++] = (ptr_t)result; return result; } #endif /* CYGWIN32 || MSWIN32 */ #if defined(ANY_MSWIN) || defined(MSWIN_XBOX1) GC_API void GC_CALL GC_win32_free_heap(void) { # if defined(USE_WINALLOC) && !defined(REDIRECT_MALLOC) GC_free_malloc_heap_list(); # endif # if defined(CYGWIN32) || defined(MSWIN32) # ifndef MSWINRT_FLAVOR # ifdef MSWIN32 if (GLOBAL_ALLOC_TEST) # endif { while (GC_n_heap_bases > 0) { GC_n_heap_bases--; # ifdef CYGWIN32 /* FIXME: Is it OK to use non-GC `free()` here? */ # else GlobalFree(GC_heap_bases[GC_n_heap_bases]); # endif GC_heap_bases[GC_n_heap_bases] = 0; } return; } # endif /* !MSWINRT_FLAVOR */ # ifndef CYGWIN32 /* Avoiding `VirtualAlloc` leak. */ while (GC_n_heap_bases > 0) { VirtualFree(GC_heap_bases[--GC_n_heap_bases], 0, MEM_RELEASE); GC_heap_bases[GC_n_heap_bases] = 0; } # endif # endif } #endif /* ANY_MSWIN || MSWIN_XBOX1 */ #if (defined(USE_MUNMAP) || defined(MPROTECT_VDB)) && !defined(USE_WINALLOC) # define ABORT_ON_REMAP_FAIL(C_msg_prefix, start_addr, len) \ ABORT_ARG3(C_msg_prefix " failed", " at %p (length %lu), errno= %d", \ (void *)(start_addr), (unsigned long)(len), errno) #endif #ifdef USE_MUNMAP # if !defined(NN_PLATFORM_CTR) && !defined(MSWIN32) && !defined(MSWINCE) \ && !defined(MSWIN_XBOX1) # ifdef SN_TARGET_PS3 # include # else # include # endif # include # endif /* * Compute a page-aligned starting address for the memory unmap * operation on a block of size `bytes` starting at `start`. * Return `NULL` if the block is too small to make this feasible. */ STATIC ptr_t GC_unmap_start(ptr_t start, size_t bytes) { ptr_t result; GC_ASSERT(GC_page_size != 0); result = PTR_ALIGN_UP(start, GC_page_size); if (ADDR_LT(start + bytes, result + GC_page_size)) return NULL; return result; } /* * We assume that `GC_remap` is called on exactly the same range as * the previous call to `GC_unmap`. It is safe to consistently round * the endpoints in both places. */ static void block_unmap_inner(ptr_t start_addr, size_t len) { if (0 == start_addr) return; # ifdef USE_WINALLOC /* * Under Win32/WinCE we commit (map) and decommit (unmap) memory * using `VirtualAlloc()` and `VirtualFree()`. These functions * work on individual allocations of virtual memory, made * previously using `VirtualAlloc()` with the `MEM_RESERVE` flag. * The ranges we need to (de)commit may span several of these * allocations; therefore we use `VirtualQuery()` to check * allocation lengths, and split up the range as necessary. */ while (len != 0) { MEMORY_BASIC_INFORMATION mem_info; word free_len; if (VirtualQuery(start_addr, &mem_info, sizeof(mem_info)) != sizeof(mem_info)) ABORT("Weird VirtualQuery result"); free_len = (len < mem_info.RegionSize) ? len : mem_info.RegionSize; if (!VirtualFree(start_addr, free_len, MEM_DECOMMIT)) ABORT("VirtualFree failed"); GC_unmapped_bytes += free_len; start_addr += free_len; len -= free_len; } # else if (len != 0) { # ifdef SN_TARGET_PS3 ps3_free_mem(start_addr, len); # elif defined(AIX) || defined(COSMO) || defined(CYGWIN32) \ || defined(HPUX) \ || (defined(LINUX) && !defined(PREFER_MMAP_PROT_NONE)) /* * On AIX, `mmap(PROT_NONE)` fails with `ENOMEM` unless the * environment variable `XPG_SUS_ENV` is set to `ON`. * On Cygwin, calling `mmap()` with the new protection flags on * an existing memory map with `MAP_FIXED` is broken. * However, calling `mprotect()` on the given address range * with `PROT_NONE` seems to work fine. On Linux, low `RLIMIT_AS` * value may lead to `mmap()` failure. */ # if (defined(COSMO) || defined(LINUX)) \ && !defined(FORCE_MPROTECT_BEFORE_MADVISE) /* On Linux, at least, `madvise()` should be sufficient. */ # else if (mprotect(start_addr, len, PROT_NONE)) ABORT_ON_REMAP_FAIL("unmap: mprotect", start_addr, len); # endif # if !defined(CYGWIN32) /* * On Linux (and some other platforms probably), `mprotect(PROT_NONE)` * is just disabling access to the pages but not returning them to OS. */ if (madvise(start_addr, len, MADV_DONTNEED) == -1) ABORT_ON_REMAP_FAIL("unmap: madvise", start_addr, len); # endif # else /* * We immediately remap it to prevent an intervening `mmap()` from * accidentally grabbing the same address space. */ void *result = mmap(start_addr, len, PROT_NONE, MAP_PRIVATE | MAP_FIXED | OPT_MAP_ANON, zero_fd, 0 /* `offset` */); if (UNLIKELY(MAP_FAILED == result)) ABORT_ON_REMAP_FAIL("unmap: mmap", start_addr, len); if (result != start_addr) ABORT("unmap: mmap() result differs from start_addr"); # if defined(CPPCHECK) || defined(LINT2) /* Explicitly store the resource handle to a global variable. */ GC_noop1_ptr(result); # endif # endif GC_unmapped_bytes += len; } # endif } /* Compute end address for an unmap operation on the indicated block. */ GC_INLINE ptr_t GC_unmap_end(ptr_t start, size_t bytes) { return (ptr_t)HBLK_PAGE_ALIGNED(start + bytes); } GC_INNER void GC_unmap(ptr_t start, size_t bytes) { ptr_t start_addr = GC_unmap_start(start, bytes); ptr_t end_addr = GC_unmap_end(start, bytes); block_unmap_inner(start_addr, (size_t)(end_addr - start_addr)); } GC_INNER void GC_remap(ptr_t start, size_t bytes) { ptr_t start_addr = GC_unmap_start(start, bytes); ptr_t end_addr = GC_unmap_end(start, bytes); word len = (word)(end_addr - start_addr); if (0 == start_addr) { return; } /* FIXME: Handle out-of-memory correctly (at least for Win32). */ # ifdef USE_WINALLOC while (len != 0) { MEMORY_BASIC_INFORMATION mem_info; word alloc_len; ptr_t result; if (VirtualQuery(start_addr, &mem_info, sizeof(mem_info)) != sizeof(mem_info)) ABORT("Weird VirtualQuery result"); alloc_len = (len < mem_info.RegionSize) ? len : mem_info.RegionSize; result = (ptr_t)VirtualAlloc(start_addr, alloc_len, MEM_COMMIT, GC_pages_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE); if (result != start_addr) { if (GetLastError() == ERROR_NOT_ENOUGH_MEMORY || GetLastError() == ERROR_OUTOFMEMORY) { ABORT("Not enough memory to process remapping"); } else { ABORT("VirtualAlloc remapping failed"); } } # ifdef LINT2 GC_noop1_ptr(result); # endif GC_ASSERT(GC_unmapped_bytes >= alloc_len); GC_unmapped_bytes -= alloc_len; start_addr += alloc_len; len -= alloc_len; } # undef IGNORE_PAGES_EXECUTABLE # else /* It was already remapped with `PROT_NONE`. */ { # if !defined(SN_TARGET_PS3) && !defined(FORCE_MPROTECT_BEFORE_MADVISE) \ && (defined(LINUX) && !defined(PREFER_MMAP_PROT_NONE) \ || defined(COSMO)) /* Nothing to unprotect as `madvise()` is just a hint. */ # elif defined(COSMO) || defined(NACL) || defined(NETBSD) /* * NaCl does not expose `mprotect`, but `mmap` should work fine. * In case of NetBSD, `mprotect` fails (unlike `mmap`) even without * `PROT_EXEC` if PaX `MPROTECT` feature is enabled. */ void *result = mmap( start_addr, len, (PROT_READ | PROT_WRITE) | (GC_pages_executable ? PROT_EXEC : 0), MAP_PRIVATE | MAP_FIXED | OPT_MAP_ANON, zero_fd, 0 /* `offset` */); if (UNLIKELY(MAP_FAILED == result)) ABORT_ON_REMAP_FAIL("remap: mmap", start_addr, len); if (result != start_addr) ABORT("remap: mmap() result differs from start_addr"); # if defined(CPPCHECK) || defined(LINT2) GC_noop1_ptr(result); # endif # undef IGNORE_PAGES_EXECUTABLE # else if (mprotect(start_addr, len, (PROT_READ | PROT_WRITE) | (GC_pages_executable ? PROT_EXEC : 0))) ABORT_ON_REMAP_FAIL("remap: mprotect", start_addr, len); # undef IGNORE_PAGES_EXECUTABLE # endif /* !NACL */ } GC_ASSERT(GC_unmapped_bytes >= len); GC_unmapped_bytes -= len; # endif } GC_INNER void GC_unmap_gap(ptr_t start1, size_t bytes1, ptr_t start2, size_t bytes2) { ptr_t start1_addr = GC_unmap_start(start1, bytes1); ptr_t end1_addr = GC_unmap_end(start1, bytes1); ptr_t start2_addr = GC_unmap_start(start2, bytes2); ptr_t start_addr = end1_addr; ptr_t end_addr = start2_addr; GC_ASSERT(start1 + bytes1 == start2); if (0 == start1_addr) start_addr = GC_unmap_start(start1, bytes1 + bytes2); if (0 == start2_addr) end_addr = GC_unmap_end(start1, bytes1 + bytes2); block_unmap_inner(start_addr, (size_t)(end_addr - start_addr)); } #endif /* USE_MUNMAP */ /* * Routine for pushing any additional roots. In the multi-threaded * environment, this is also responsible for marking from thread stacks. */ #ifndef THREADS # if defined(EMSCRIPTEN) && defined(EMSCRIPTEN_ASYNCIFY) # include static void scan_regs_cb(void *begin, void *finish) { GC_push_all_stack((ptr_t)begin, (ptr_t)finish); } STATIC void GC_CALLBACK GC_default_push_other_roots(void) { /* Note: this needs `-sASYNCIFY` linker flag. */ emscripten_scan_registers(scan_regs_cb); } # else # define GC_default_push_other_roots 0 # endif #else /* THREADS */ # if defined(SN_TARGET_PS3) STATIC void GC_CALLBACK GC_default_push_other_roots(void) { ABORT("GC_default_push_other_roots is not implemented"); } GC_INNER void GC_push_thread_structures(void) { ABORT("GC_push_thread_structures is not implemented"); } # else /* GC_PTHREADS, etc. */ STATIC void GC_CALLBACK GC_default_push_other_roots(void) { GC_push_all_stacks(); } # endif #endif /* THREADS */ GC_push_other_roots_proc GC_push_other_roots = GC_default_push_other_roots; GC_API void GC_CALL GC_set_push_other_roots(GC_push_other_roots_proc fn) { GC_push_other_roots = fn; } GC_API GC_push_other_roots_proc GC_CALL GC_get_push_other_roots(void) { return GC_push_other_roots; } #if defined(SOFT_VDB) && !defined(NO_SOFT_VDB_LINUX_VER_RUNTIME_CHECK) \ || (defined(GLIBC_2_19_TSX_BUG) && defined(GC_PTHREADS_PARAMARK)) GC_INNER int GC_parse_version(int *pminor, const char *pverstr) { char *endp; unsigned long value = strtoul(pverstr, &endp, 10); int major = (int)value; if (major < 0 || (char *)pverstr == endp || (unsigned)major != value) { /* Parse error. */ return -1; } if (*endp != '.') { /* No minor part. */ *pminor = -1; } else { value = strtoul(endp + 1, &endp, 10); *pminor = (int)value; if (*pminor < 0 || (unsigned)(*pminor) != value) { return -1; } } return major; } #endif /* * Routines for accessing dirty bits on virtual pages. There are 6 ways to * maintain this information, as of now: * * - `DEFAULT_VDB`: A simple dummy implementation that treats every page * as possibly dirty. This makes incremental collection useless, but * the implementation is still correct. * * - `MANUAL_VDB`: Stacks and static data are always considered dirty. * Heap pages are considered dirty if `GC_dirty(p)` has been called on * some `p` pointing to somewhere inside an object on that page. * A `GC_dirty()` call on a large object directly dirties only a single * page, but for the manual VDB we are careful to treat an object with * a dirty page as completely dirty. In order to avoid races, an object * must be marked dirty after it is written, and a reference to the * object must be kept on a stack or in a register in the interim. * With threads enabled, an object directly reachable from the stack at * the time of a collection is treated as dirty. In the single-threaded * mode, it suffices to ensure that no collection can take place between * the pointer assignment and the `GC_dirty()` call. * * - `PROC_VDB`: Use the `/proc` facility for reading dirty bits. * Only works under some SVR4 variants. Even then, it may be too slow * to be entirely satisfactory. Requires reading dirty bits for entire * address space. Implementations tend to assume that the client is * a (slow) debugger. * * - `SOFT_VDB`: Use the `/proc` facility for reading soft-dirty PTEs * (page table entries). Works on Linux 3.18+ if the kernel is * properly configured. The proposed implementation iterates over * `GC_heap_sects` and `GC_static_roots` examining the soft-dirty bit * of the `word` elements in `/proc/self/pagemap` file corresponding to * the pages of the sections; finally all soft-dirty bits of the process * are cleared (by writing some special value to `/proc/self/clear_refs` * file). In case the soft-dirty bit is not supported by the kernel, * `MPROTECT_VDB` may be defined as a fall back strategy. * * - `MPROTECT_VDB`: Protect pages and then catch the faults to keep * track of dirtied pages. The implementation (and implementability) * is highly system-dependent. This usually fails when system calls * write to a protected page. We prevent the `read` system call from * doing so. It is the clients responsibility to make sure that other * system calls are similarly protected or write only to the stack. * * - `GWW_VDB`: Use the Win32 `GetWriteWatch` function, if available, to * read dirty bits. In case it is not available (because we are * running on Windows 95, Windows 2000 or earlier), `MPROTECT_VDB` may * be defined as a fall back strategy. */ #if (defined(CHECKSUMS) && defined(GWW_VDB)) || defined(PROC_VDB) /* Add all pages in `pht2` to `pht1`. */ STATIC void GC_or_pages(page_hash_table pht1, const word *pht2) { size_t i; for (i = 0; i < PHT_SIZE; i++) pht1[i] |= pht2[i]; } #endif /* CHECKSUMS && GWW_VDB || PROC_VDB */ #ifdef GWW_VDB /* * Note: this is still susceptible to overflow, if there are very large * allocations, and everything is dirty. */ # define GC_GWW_BUF_LEN (MAXHINCR * HBLKSIZE / 4096 /* x86 page size */) static PVOID gww_buf[GC_GWW_BUF_LEN]; # ifndef MPROTECT_VDB # define GC_gww_dirty_init GC_dirty_init # endif GC_INNER GC_bool GC_gww_dirty_init(void) { /* No assumption about the allocator lock. */ detect_GetWriteWatch(); return GC_GWW_AVAILABLE(); } GC_INLINE void GC_gww_read_dirty(GC_bool output_unneeded) { size_t i; GC_ASSERT(I_HOLD_LOCK()); if (!output_unneeded) BZERO(GC_grungy_pages, sizeof(GC_grungy_pages)); for (i = 0; i < GC_n_heap_sects; ++i) { GC_ULONG_PTR count; do { PVOID *pages = gww_buf; DWORD page_size; count = GC_GWW_BUF_LEN; /* * `GetWriteWatch()` is documented as returning nonzero when * it fails, but the documentation does not explicitly say why * it would fail or what its behavior will be if it fails. * It does appear to fail, at least on recent Win2K instances, * if the underlying memory was not allocated with the appropriate * flag. This is common if `GC_enable_incremental` is called * shortly after the collector initialization. To avoid modifying * the interface, we silently work around such a failure, it only * affects the initial (small) heap allocation. If there are * more dirty pages than will fit in the buffer, this is not * treated as a failure; we must check the page count in the * loop condition. Since each partial call will reset the * status of some pages, this should eventually terminate even * in the overflow case. */ if ((*(GetWriteWatch_type)(GC_funcptr_uint)GetWriteWatch_func)( WRITE_WATCH_FLAG_RESET, GC_heap_sects[i].hs_start, GC_heap_sects[i].hs_bytes, pages, &count, &page_size) != 0) { static int warn_count = 0; struct hblk *start = (struct hblk *)GC_heap_sects[i].hs_start; static const struct hblk *last_warned = NULL; size_t nblocks = divHBLKSZ(GC_heap_sects[i].hs_bytes); if (i != 0 && last_warned != start && warn_count++ < 5) { last_warned = start; WARN("GC_gww_read_dirty unexpectedly failed at %p:" " Falling back to marking all pages dirty\n", start); } if (!output_unneeded) { size_t j; for (j = 0; j < nblocks; ++j) { size_t index = PHT_HASH(start + j); set_pht_entry_from_index(GC_grungy_pages, index); } } /* Done with this section. */ count = 1; } else if (!output_unneeded) { /*< succeeded */ const PVOID *pages_end = pages + count; while (pages != pages_end) { struct hblk *h = (struct hblk *)(*pages++); ptr_t h_end = (ptr_t)h + page_size; do { set_pht_entry_from_index(GC_grungy_pages, PHT_HASH(h)); h++; } while (ADDR_LT((ptr_t)h, h_end)); } } } while (count == GC_GWW_BUF_LEN); /* * FIXME: It is unclear from Microsoft's documentation if this loop * is useful. We suspect the call just fails if the buffer fills up. * But that should still be handled correctly. */ } # ifdef CHECKSUMS GC_ASSERT(!output_unneeded); GC_or_pages(GC_written_pages, GC_grungy_pages); # endif } #elif defined(SOFT_VDB) static int clear_refs_fd = -1; # define GC_GWW_AVAILABLE() (clear_refs_fd != -1) #else # define GC_GWW_AVAILABLE() FALSE #endif /* !GWW_VDB && !SOFT_VDB */ #ifdef DEFAULT_VDB /* * The client asserts that unallocated pages in the heap are never * written. */ GC_INNER GC_bool GC_dirty_init(void) { GC_VERBOSE_LOG_PRINTF("Initializing DEFAULT_VDB...\n"); /* `GC_dirty_pages` and `GC_grungy_pages` are already cleared. */ return TRUE; } #endif /* DEFAULT_VDB */ #if !defined(NO_MANUAL_VDB) || defined(MPROTECT_VDB) # if !defined(THREADS) || defined(HAVE_LOCKFREE_AO_OR) # ifdef MPROTECT_VDB # define async_set_pht_entry_from_index(db, index) \ set_pht_entry_from_index_concurrent_volatile(db, index) # else # define async_set_pht_entry_from_index(db, index) \ set_pht_entry_from_index_concurrent(db, index) # endif # elif defined(NEED_FAULT_HANDLER_LOCK) /* * We need to lock around the bitmap update (in the write fault * handler or `GC_dirty`) in order to avoid the risk of losing a bit. * We do this with a test-and-set spin lock if possible. */ static void async_set_pht_entry_from_index(volatile page_hash_table db, size_t index) { GC_acquire_dirty_lock(); set_pht_entry_from_index(db, index); GC_release_dirty_lock(); } # else /* THREADS && !NEED_FAULT_HANDLER_LOCK */ # error No test_and_set operation: Introduces a race. # endif #endif /* !NO_MANUAL_VDB || MPROTECT_VDB */ #ifdef MPROTECT_VDB /* * This implementation maintains dirty bits itself by catching write * faults and keeping track of them. We assume nobody else catches * `SIGBUS` or `SIGSEGV`. We assume no write faults occur in system * calls. This means that clients must ensure that system calls do * not write to the write-protected heap. Probably the best way to * do this is to ensure that system calls write at most to * pointer-free objects in the heap, and do even that only if we are * on a platform on which those are not protected (or the collector * is built with `DONT_PROTECT_PTRFREE` defined). We assume the page * size is a multiple of `HBLKSIZE`. */ # ifdef DARWIN /* `#define BROKEN_EXCEPTION_HANDLING` */ /* * Using `vm_protect` (a `mach` `syscall`) over `mprotect` (a BSD `syscall`) * seems to decrease the likelihood of some of the problems described below. */ # include STATIC mach_port_t GC_task_self = 0; # define PROTECT_INNER(addr, len, allow_write, C_msg_prefix) \ if (vm_protect(GC_task_self, (vm_address_t)(addr), (vm_size_t)(len), \ FALSE, \ VM_PROT_READ | ((allow_write) ? VM_PROT_WRITE : 0) \ | (GC_pages_executable ? VM_PROT_EXECUTE : 0)) \ == KERN_SUCCESS) { \ } else \ ABORT(C_msg_prefix "vm_protect() failed") # elif !defined(USE_WINALLOC) # include # if !defined(AIX) && !defined(CYGWIN32) && !defined(HAIKU) # include # endif # define PROTECT_INNER(addr, len, allow_write, C_msg_prefix) \ if (mprotect((caddr_t)(addr), (size_t)(len), \ PROT_READ | ((allow_write) ? PROT_WRITE : 0) \ | (GC_pages_executable ? PROT_EXEC : 0)) \ >= 0) { \ } else if (GC_pages_executable) { \ ABORT_ON_REMAP_FAIL(C_msg_prefix "mprotect vdb executable pages", \ addr, len); \ } else \ ABORT_ON_REMAP_FAIL(C_msg_prefix "mprotect vdb", addr, len) # undef IGNORE_PAGES_EXECUTABLE # else /* USE_WINALLOC */ static DWORD protect_junk; # define PROTECT_INNER(addr, len, allow_write, C_msg_prefix) \ if (VirtualProtect(addr, len, \ GC_pages_executable \ ? ((allow_write) ? PAGE_EXECUTE_READWRITE \ : PAGE_EXECUTE_READ) \ : (allow_write) ? PAGE_READWRITE \ : PAGE_READONLY, \ &protect_junk)) { \ } else \ ABORT_ARG1(C_msg_prefix "VirtualProtect failed", ": errcode= 0x%X", \ (unsigned)GetLastError()) # endif /* USE_WINALLOC */ # define PROTECT(addr, len) PROTECT_INNER(addr, len, FALSE, "") # define UNPROTECT(addr, len) PROTECT_INNER(addr, len, TRUE, "un-") # if defined(MSWIN32) typedef LPTOP_LEVEL_EXCEPTION_FILTER SIG_HNDLR_PTR; # undef SIG_DFL # define SIG_DFL ((LPTOP_LEVEL_EXCEPTION_FILTER)(~(GC_funcptr_uint)0)) # elif defined(MSWINCE) typedef LONG(WINAPI *SIG_HNDLR_PTR)(struct _EXCEPTION_POINTERS *); # undef SIG_DFL # define SIG_DFL ((SIG_HNDLR_PTR)(~(GC_funcptr_uint)0)) # elif defined(DARWIN) # ifdef BROKEN_EXCEPTION_HANDLING typedef void (*SIG_HNDLR_PTR)(); # endif # else typedef void (*SIG_HNDLR_PTR)(int, siginfo_t *, void *); typedef void (*PLAIN_HNDLR_PTR)(int); # endif /* !DARWIN && !MSWIN32 && !MSWINCE */ # ifndef DARWIN /* Also old `MSWIN32` `ACCESS_VIOLATION` filter. */ STATIC SIG_HNDLR_PTR GC_old_segv_handler = 0; # ifdef USE_BUS_SIGACT STATIC SIG_HNDLR_PTR GC_old_bus_handler = 0; STATIC GC_bool GC_old_bus_handler_used_si = FALSE; # endif # if !defined(MSWIN32) && !defined(MSWINCE) STATIC GC_bool GC_old_segv_handler_used_si = FALSE; # endif # endif /* !DARWIN */ # ifdef THREADS /* * This function is used only by the fault handler. Potential data * race between this function and `GC_install_header`, `GC_remove_header` * should not be harmful because the added or removed header should be * already unprotected. */ GC_ATTR_NO_SANITIZE_THREAD static GC_bool is_header_found_async(const void *p) { # ifdef HASH_TL hdr *result; GET_HDR(p, result); return result != NULL; # else return HDR_INNER(p) != NULL; # endif } # else # define is_header_found_async(p) (HDR(p) != NULL) # endif /* !THREADS */ # ifndef DARWIN # if !defined(MSWIN32) && !defined(MSWINCE) # include # ifdef USE_BUS_SIGACT # define SIG_OK (sig == SIGBUS || sig == SIGSEGV) # else /* Catch `SIGSEGV` but ignore `SIGBUS`. */ # define SIG_OK (sig == SIGSEGV) # endif # if defined(FREEBSD) || defined(OPENBSD) # ifndef SEGV_ACCERR # define SEGV_ACCERR 2 # endif # if defined(AARCH64) || defined(ARM32) || defined(MIPS) \ || (__FreeBSD__ >= 7 || defined(OPENBSD)) # define CODE_OK (si->si_code == SEGV_ACCERR) # elif defined(POWERPC) /* Pretend that we are AIM. */ # define AIM # include # define CODE_OK \ (si->si_code == EXC_DSI || si->si_code == SEGV_ACCERR) # else # define CODE_OK \ (si->si_code == BUS_PAGE_FAULT || si->si_code == SEGV_ACCERR) # endif # elif defined(OSF1) # define CODE_OK (si->si_code == 2) /*< experimentally determined */ # elif defined(IRIX5) # define CODE_OK (si->si_code == EACCES) # elif defined(AIX) || defined(COSMO) || defined(CYGWIN32) \ || defined(HAIKU) || defined(HURD) || defined(LINUX) \ || defined(NETBSD) /* * Linux/i686: Empirically `c.trapno == 14`, but is that useful? * Should probably consider alignment issues on other architectures. */ # define CODE_OK TRUE # elif defined(HPUX) # define CODE_OK \ (si->si_code == SEGV_ACCERR || si->si_code == BUS_ADRERR \ || si->si_code == BUS_UNKNOWN || si->si_code == SEGV_UNKNOWN \ || si->si_code == BUS_OBJERR) # elif defined(SUNOS5SIGS) # define CODE_OK (si->si_code == SEGV_ACCERR) # endif # ifndef NO_GETCONTEXT # include # endif STATIC void GC_write_fault_handler(int sig, siginfo_t *si, void *raw_sc) # else /* MSWIN32 || MSWINCE */ # define SIG_OK \ (exc_info->ExceptionRecord->ExceptionCode == STATUS_ACCESS_VIOLATION) # define CODE_OK \ (exc_info->ExceptionRecord->ExceptionInformation[0] \ == 1) /*< write fault */ STATIC LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info) # endif { # if !defined(MSWIN32) && !defined(MSWINCE) char *addr = (char *)si->si_addr; # else char *addr = (char *)exc_info->ExceptionRecord->ExceptionInformation[1]; # endif if (SIG_OK && CODE_OK) { struct hblk *h = HBLK_PAGE_ALIGNED(addr); GC_bool in_allocd_block; size_t i; GC_ASSERT(GC_page_size != 0); # ifdef CHECKSUMS GC_record_fault(h); # endif # ifdef SUNOS5SIGS /* Address is only within the correct physical page. */ in_allocd_block = FALSE; for (i = 0; i < divHBLKSZ(GC_page_size); i++) { if (is_header_found_async(&h[i])) { in_allocd_block = TRUE; break; } } # else in_allocd_block = is_header_found_async(addr); # endif if (!in_allocd_block) { /* * FIXME: We should make sure that we invoke the old handler with the * appropriate calling sequence, which often depends on `SA_SIGINFO`. */ /* Heap blocks now begin and end on page boundaries. */ SIG_HNDLR_PTR old_handler; # if defined(MSWIN32) || defined(MSWINCE) old_handler = GC_old_segv_handler; # else GC_bool used_si; # ifdef USE_BUS_SIGACT if (sig == SIGBUS) { old_handler = GC_old_bus_handler; used_si = GC_old_bus_handler_used_si; } else # endif /* else */ { old_handler = GC_old_segv_handler; used_si = GC_old_segv_handler_used_si; } # endif if ((GC_funcptr_uint)old_handler == (GC_funcptr_uint)SIG_DFL) { # if !defined(MSWIN32) && !defined(MSWINCE) ABORT_ARG1("Unexpected segmentation fault outside heap", " at %p", (void *)addr); # else return EXCEPTION_CONTINUE_SEARCH; # endif } else { /* * FIXME: This code should probably check if the old signal handler * used the traditional style and if so, call it using that style. */ # if defined(MSWIN32) || defined(MSWINCE) return (*old_handler)(exc_info); # else if (used_si) ((SIG_HNDLR_PTR)old_handler)(sig, si, raw_sc); else /* FIXME: Should pass nonstandard arguments as well. */ ((PLAIN_HNDLR_PTR)(GC_funcptr_uint)old_handler)(sig); return; # endif } } UNPROTECT(h, GC_page_size); /* * We need to make sure that no collection occurs between the * `UNPROTECT()` call and the setting of the dirty bit. * Otherwise a write by a third thread might go unnoticed. * Reversing the order is just as bad, since we would end up * unprotecting a page in a collection cycle during which it is not * marked. Currently we do this by disabling the thread stopping * signals while this handler is running. An alternative might be * to record the fact that we are about to unprotect, or have just * unprotected a page in the collector's thread structure, and then * to have the thread stopping code set the dirty flag, if necessary. */ for (i = 0; i < divHBLKSZ(GC_page_size); i++) { size_t index = PHT_HASH(h + i); async_set_pht_entry_from_index(GC_dirty_pages, index); } /* * The `write()` may not take place before dirty bits are read. * But then we will fault again... */ # if defined(MSWIN32) || defined(MSWINCE) return EXCEPTION_CONTINUE_EXECUTION; # else return; # endif } # if defined(MSWIN32) || defined(MSWINCE) return EXCEPTION_CONTINUE_SEARCH; # else ABORT_ARG1("Unexpected bus error or segmentation fault", " at %p", (void *)addr); # endif } # if defined(GC_WIN32_THREADS) && !defined(CYGWIN32) GC_INNER void GC_set_write_fault_handler(void) { SetUnhandledExceptionFilter(GC_write_fault_handler); } # endif # ifdef SOFT_VDB static GC_bool soft_dirty_init(void); # endif GC_INNER GC_bool GC_dirty_init(void) { # if !defined(MSWIN32) && !defined(MSWINCE) struct sigaction act, oldact; # endif GC_ASSERT(I_HOLD_LOCK()); # ifdef COUNT_PROTECTED_REGIONS GC_ASSERT(GC_page_size != 0); if ((GC_signed_word)(GC_heapsize / (word)GC_page_size) >= ((GC_signed_word)GC_UNMAPPED_REGIONS_SOFT_LIMIT - GC_num_unmapped_regions) * 2) { GC_COND_LOG_PRINTF("Cannot turn on GC incremental mode" " as heap contains too many pages\n"); return FALSE; } # endif # if !defined(MSWIN32) && !defined(MSWINCE) act.sa_flags = SA_RESTART | SA_SIGINFO; act.sa_sigaction = GC_write_fault_handler; (void)sigemptyset(&act.sa_mask); # ifdef SIGNAL_BASED_STOP_WORLD /* * Arrange to postpone the signal while we are in a write fault handler. * This effectively makes the handler atomic w.r.t. stopping the world * for the collection. */ (void)sigaddset(&act.sa_mask, GC_get_suspend_signal()); # endif # endif /* !MSWIN32 */ GC_VERBOSE_LOG_PRINTF( "Initializing mprotect virtual dirty bit implementation\n"); if (GC_page_size % HBLKSIZE != 0) { ABORT("Page size not multiple of HBLKSIZE"); } # ifdef GWW_VDB if (GC_gww_dirty_init()) { GC_COND_LOG_PRINTF("Using GetWriteWatch()\n"); return TRUE; } # elif defined(SOFT_VDB) # ifdef CHECK_SOFT_VDB if (!soft_dirty_init()) ABORT("Soft-dirty bit support is missing"); # else if (soft_dirty_init()) { GC_COND_LOG_PRINTF("Using soft-dirty bit feature\n"); return TRUE; } # endif # endif # ifdef MSWIN32 GC_old_segv_handler = SetUnhandledExceptionFilter(GC_write_fault_handler); if (GC_old_segv_handler != NULL) { GC_COND_LOG_PRINTF("Replaced other UnhandledExceptionFilter\n"); } else { GC_old_segv_handler = SIG_DFL; } # elif defined(MSWINCE) { /* `MPROTECT_VDB` is unsupported for WinCE at present. */ /* FIXME: Implement (if possible). */ } # else /* `act.sa_restorer` is deprecated and should not be initialized. */ # if defined(IRIX5) && defined(THREADS) sigaction(SIGSEGV, 0, &oldact); sigaction(SIGSEGV, &act, 0); # else { int res = sigaction(SIGSEGV, &act, &oldact); if (res != 0) ABORT("Sigaction failed"); } # endif if (oldact.sa_flags & SA_SIGINFO) { GC_old_segv_handler = oldact.sa_sigaction; GC_old_segv_handler_used_si = TRUE; } else { GC_old_segv_handler = (SIG_HNDLR_PTR)(GC_funcptr_uint)oldact.sa_handler; GC_old_segv_handler_used_si = FALSE; } if ((GC_funcptr_uint)GC_old_segv_handler == (GC_funcptr_uint)SIG_IGN) { WARN("Previously ignored segmentation violation!?\n", 0); GC_old_segv_handler = (SIG_HNDLR_PTR)(GC_funcptr_uint)SIG_DFL; } if ((GC_funcptr_uint)GC_old_segv_handler != (GC_funcptr_uint)SIG_DFL) { GC_VERBOSE_LOG_PRINTF("Replaced other SIGSEGV handler\n"); } # ifdef USE_BUS_SIGACT sigaction(SIGBUS, &act, &oldact); if ((oldact.sa_flags & SA_SIGINFO) != 0) { GC_old_bus_handler = oldact.sa_sigaction; GC_old_bus_handler_used_si = TRUE; } else { GC_old_bus_handler = (SIG_HNDLR_PTR)(GC_funcptr_uint)oldact.sa_handler; } if ((GC_funcptr_uint)GC_old_bus_handler == (GC_funcptr_uint)SIG_IGN) { WARN("Previously ignored bus error!?\n", 0); GC_old_bus_handler = (SIG_HNDLR_PTR)(GC_funcptr_uint)SIG_DFL; } else if ((GC_funcptr_uint)GC_old_bus_handler != (GC_funcptr_uint)SIG_DFL) { GC_VERBOSE_LOG_PRINTF("Replaced other SIGBUS handler\n"); } # endif # endif /* !MSWIN32 && !MSWINCE */ # if defined(CPPCHECK) && defined(ADDRESS_SANITIZER) GC_noop1((word)(GC_funcptr_uint)(&__asan_default_options)); # endif return TRUE; } # endif /* !DARWIN */ STATIC void GC_protect_heap(void) { size_t i; GC_ASSERT(GC_page_size != 0); for (i = 0; i < GC_n_heap_sects; i++) { ptr_t start = GC_heap_sects[i].hs_start; size_t len = GC_heap_sects[i].hs_bytes; struct hblk *current; struct hblk *current_start; /*< start of block to be protected */ ptr_t limit; GC_ASSERT((ADDR(start) & (GC_page_size - 1)) == 0); GC_ASSERT((len & (GC_page_size - 1)) == 0); # ifndef DONT_PROTECT_PTRFREE /* * We avoid protecting pointer-free objects unless the page size * differs from `HBLKSIZE`. */ if (GC_page_size != HBLKSIZE) { PROTECT(start, len); continue; } # endif current_start = (struct hblk *)start; limit = start + len; for (current = current_start;;) { size_t nblocks = 0; GC_bool is_ptrfree = TRUE; if (ADDR_LT((ptr_t)current, limit)) { hdr *hhdr; GET_HDR(current, hhdr); if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { /* * This can happen only if we are at the beginning of a heap * segment, and a block spans heap segments. We will handle * that block as part of the preceding segment. */ GC_ASSERT(current_start == current); current_start = ++current; continue; } if (HBLK_IS_FREE(hhdr)) { GC_ASSERT(modHBLKSZ(hhdr->hb_sz) == 0); nblocks = divHBLKSZ(hhdr->hb_sz); } else { nblocks = OBJ_SZ_TO_BLOCKS(hhdr->hb_sz); is_ptrfree = IS_PTRFREE(hhdr); } } if (is_ptrfree) { if (ADDR_LT((ptr_t)current_start, (ptr_t)current)) { # ifdef DONT_PROTECT_PTRFREE ptr_t cur_aligned = PTR_ALIGN_UP((ptr_t)current, GC_page_size); current_start = HBLK_PAGE_ALIGNED(current_start); /* * Adjacent free blocks might be protected too because * of the alignment by the page size. */ PROTECT(current_start, cur_aligned - (ptr_t)current_start); # else PROTECT(current_start, (ptr_t)current - (ptr_t)current_start); # endif } if (ADDR_GE((ptr_t)current, limit)) break; } current += nblocks; if (is_ptrfree) current_start = current; } } } # if defined(CAN_HANDLE_FORK) && defined(DARWIN) && defined(THREADS) \ || defined(COUNT_PROTECTED_REGIONS) /* Remove protection for the entire heap not updating `GC_dirty_pages`. */ STATIC void GC_unprotect_all_heap(void) { size_t i; GC_ASSERT(I_HOLD_LOCK()); GC_ASSERT(GC_auto_incremental); for (i = 0; i < GC_n_heap_sects; i++) { UNPROTECT(GC_heap_sects[i].hs_start, GC_heap_sects[i].hs_bytes); } } # endif # ifdef COUNT_PROTECTED_REGIONS GC_INNER void GC_handle_protected_regions_limit(void) { GC_ASSERT(GC_page_size != 0); /* * To prevent exceeding the limit of `vm.max_map_count`, the most * trivial (though highly restrictive) way is to turn off the * incremental collection mode (based on `mprotect`) once the number * of pages in the heap reaches that limit. */ if (GC_auto_incremental && !GC_GWW_AVAILABLE() && (GC_signed_word)(GC_heapsize / (word)GC_page_size) >= ((GC_signed_word)GC_UNMAPPED_REGIONS_SOFT_LIMIT - GC_num_unmapped_regions) * 2) { GC_unprotect_all_heap(); # ifdef DARWIN GC_task_self = 0; # endif GC_incremental = FALSE; WARN("GC incremental mode is turned off" " to prevent hitting VM maps limit\n", 0); } } # endif /* COUNT_PROTECTED_REGIONS */ #endif /* MPROTECT_VDB */ #if !defined(THREADS) && (defined(PROC_VDB) || defined(SOFT_VDB)) static pid_t saved_proc_pid; /*< `pid` used to compose `/proc` file names */ #endif #ifdef PROC_VDB /* * This implementation assumes the Solaris new structured `/proc` * pseudo-file-system from which we can read page modified bits. * This facility is far from optimal (e.g. we would like to get the * info for only some of the address space), but it avoids intercepting * system calls. */ # include # include # include # include # ifdef GC_NO_SYS_FAULT_H /* This exists only to check `PROC_VDB` code compilation (on Linux). */ # define PG_MODIFIED 1 struct prpageheader { long dummy[2]; /*< `pr_tstamp` */ long pr_nmap; long pr_npage; }; struct prasmap { GC_uintptr_t pr_vaddr; size_t pr_npage; char dummy1[64 + 8]; /*< `pr_mapname`, `pr_offset` */ int pr_mflags; int pr_pagesize; int dummy2[2]; /*< `pr_shmid`, `pr_filler` */ }; # else /* Use the new structured `/proc` definitions. */ # include # endif # define INITIAL_BUF_SZ 8192 STATIC size_t GC_proc_buf_size = INITIAL_BUF_SZ; STATIC char *GC_proc_buf = NULL; STATIC int GC_proc_fd = -1; static GC_bool proc_dirty_open_files(void) { char buf[6 + 20 + 9 + 1]; pid_t pid = getpid(); GC_snprintf_s_ld_s(buf, sizeof(buf), "/proc/", (long)pid, "/pagedata"); GC_proc_fd = open(buf, O_RDONLY); if (-1 == GC_proc_fd) { WARN("/proc open failed; cannot enable GC incremental mode\n", 0); return FALSE; } if (syscall(SYS_fcntl, GC_proc_fd, F_SETFD, FD_CLOEXEC) == -1) WARN("Could not set FD_CLOEXEC for /proc\n", 0); # ifndef THREADS /* Updated on success only. */ saved_proc_pid = pid; # endif return TRUE; } # ifdef CAN_HANDLE_FORK GC_INNER void GC_dirty_update_child(void) { GC_ASSERT(I_HOLD_LOCK()); if (-1 == GC_proc_fd) { /* The GC incremental mode is off. */ return; } close(GC_proc_fd); if (!proc_dirty_open_files()) { /* Should be safe to turn it off. */ GC_incremental = FALSE; } } # endif /* CAN_HANDLE_FORK */ GC_INNER GC_bool GC_dirty_init(void) { GC_ASSERT(I_HOLD_LOCK()); if (GC_bytes_allocd != 0 || GC_bytes_allocd_before_gc != 0) { memset(GC_written_pages, 0xff, sizeof(page_hash_table)); GC_VERBOSE_LOG_PRINTF( "Allocated %lu bytes: all pages may have been written\n", (unsigned long)(GC_bytes_allocd + GC_bytes_allocd_before_gc)); } if (!proc_dirty_open_files()) return FALSE; GC_proc_buf = GC_scratch_alloc(GC_proc_buf_size); if (GC_proc_buf == NULL) ABORT("Insufficient space for /proc read"); return TRUE; } GC_INLINE void GC_proc_read_dirty(GC_bool output_unneeded) { size_t i, nmaps; ssize_t pagedata_len; char *bufp = GC_proc_buf; GC_ASSERT(I_HOLD_LOCK()); # ifndef THREADS /* * If the current `pid` differs from the saved one, then we are in * the forked (child) process, the current `/proc` file should be * closed, the new one should be opened with the updated path. * Note, this is not needed for the multi-threaded case because * `fork_child_proc()` reopens the file right after `fork()` call. */ if (getpid() != saved_proc_pid && (-1 == GC_proc_fd /*< no need to retry */ || (close(GC_proc_fd), !proc_dirty_open_files()))) { /* Failed to reopen the file. Punt! */ if (!output_unneeded) memset(GC_grungy_pages, 0xff, sizeof(page_hash_table)); memset(GC_written_pages, 0xff, sizeof(page_hash_table)); return; } # endif for (;;) { char *new_buf; size_t new_size; pagedata_len = PROC_READ(GC_proc_fd, bufp, GC_proc_buf_size); if (LIKELY(pagedata_len != -1)) break; if (errno != E2BIG) { WARN("read /proc failed, errno= %" WARN_PRIdPTR "\n", (GC_signed_word)errno); /* Punt. */ if (!output_unneeded) memset(GC_grungy_pages, 0xff, sizeof(page_hash_table)); memset(GC_written_pages, 0xff, sizeof(page_hash_table)); return; } /* Retry with larger buffer. */ new_size = 2 * GC_proc_buf_size; /* * Alternatively, we could use `fstat()` to determine the required * buffer size. */ # ifdef DEBUG_DIRTY_BITS GC_log_printf("Growing proc buf to %lu bytes at collection #%lu\n", (unsigned long)new_size, (unsigned long)GC_gc_no + 1); # endif new_buf = GC_scratch_alloc(new_size); if (new_buf != NULL) { GC_scratch_recycle_no_gww(bufp, GC_proc_buf_size); GC_proc_buf = bufp = new_buf; GC_proc_buf_size = new_size; } } GC_ASSERT((size_t)pagedata_len <= GC_proc_buf_size); /* Copy dirty bits into `GC_grungy_pages`. */ BZERO(GC_grungy_pages, sizeof(GC_grungy_pages)); nmaps = (size_t)(((struct prpageheader *)bufp)->pr_nmap); # ifdef DEBUG_DIRTY_BITS GC_log_printf("Proc VDB read: pr_nmap= %u, pr_npage= %ld\n", (unsigned)nmaps, ((struct prpageheader *)bufp)->pr_npage); # endif # if defined(GC_NO_SYS_FAULT_H) && defined(CPPCHECK) GC_noop1(((struct prpageheader *)bufp)->dummy[0]); # endif bufp += sizeof(struct prpageheader); for (i = 0; i < nmaps; i++) { struct prasmap *map = (struct prasmap *)bufp; ptr_t vaddr, limit; unsigned long npages = 0; unsigned pagesize; bufp += sizeof(struct prasmap); /* Ensure no buffer overrun. */ if (bufp - GC_proc_buf < pagedata_len) npages = (unsigned long)map->pr_npage; if (bufp - GC_proc_buf > pagedata_len - (ssize_t)npages) ABORT("Wrong pr_nmap or pr_npage read from /proc"); vaddr = (ptr_t)map->pr_vaddr; pagesize = (unsigned)map->pr_pagesize; # if defined(GC_NO_SYS_FAULT_H) && defined(CPPCHECK) GC_noop1(map->dummy1[0] + map->dummy2[0]); # endif # ifdef DEBUG_DIRTY_BITS GC_log_printf("pr_vaddr= %p, npage= %lu, mflags= 0x%x, pagesize= 0x%x\n", (void *)vaddr, npages, map->pr_mflags, pagesize); # endif if (0 == pagesize || ((pagesize - 1) & pagesize) != 0) ABORT("Wrong pagesize read from /proc"); limit = vaddr + pagesize * npages; for (; ADDR_LT(vaddr, limit); vaddr += pagesize) { if ((*bufp++) & PG_MODIFIED) { struct hblk *h; ptr_t next_vaddr = vaddr + pagesize; # ifdef DEBUG_DIRTY_BITS GC_log_printf("dirty page at: %p\n", (void *)vaddr); # endif for (h = (struct hblk *)vaddr; ADDR_LT((ptr_t)h, next_vaddr); h++) { size_t index = PHT_HASH(h); set_pht_entry_from_index(GC_grungy_pages, index); } } } /* * According to the new structured `pagedata` file format, an 8-byte * alignment is enforced (preceding the next `struct prasmap`) * regardless of the pointer size. */ bufp = PTR_ALIGN_UP(bufp, 8); } # ifdef DEBUG_DIRTY_BITS GC_log_printf("Proc VDB read done\n"); # endif /* Update `GC_written_pages` (even if `output_unneeded`). */ GC_or_pages(GC_written_pages, GC_grungy_pages); } #endif /* PROC_VDB */ #ifdef SOFT_VDB # ifndef VDB_BUF_SZ # define VDB_BUF_SZ 16384 # endif static int open_proc_fd(pid_t pid, const char *slash_filename, int mode) { int f; char buf[6 + 20 + 11 + 1]; GC_snprintf_s_ld_s(buf, sizeof(buf), "/proc/", (long)pid, slash_filename); f = open(buf, mode); if (-1 == f) { WARN("/proc/self%s open failed; cannot enable GC incremental mode\n", slash_filename); } else if (fcntl(f, F_SETFD, FD_CLOEXEC) == -1) { WARN("Could not set FD_CLOEXEC for /proc\n", 0); } return f; } # include /*< for `uint64_t` */ typedef uint64_t pagemap_elem_t; static pagemap_elem_t *soft_vdb_buf; static int pagemap_fd; static GC_bool soft_dirty_open_files(void) { pid_t pid = getpid(); clear_refs_fd = open_proc_fd(pid, "/clear_refs", O_WRONLY); if (-1 == clear_refs_fd) return FALSE; pagemap_fd = open_proc_fd(pid, "/pagemap", O_RDONLY); if (-1 == pagemap_fd) { close(clear_refs_fd); clear_refs_fd = -1; return FALSE; } # ifndef THREADS /* Updated on success only. */ saved_proc_pid = pid; # endif return TRUE; } # ifdef CAN_HANDLE_FORK GC_INNER void GC_dirty_update_child(void) { GC_ASSERT(I_HOLD_LOCK()); if (-1 == clear_refs_fd) { /* The GC incremental mode is off. */ return; } close(clear_refs_fd); close(pagemap_fd); if (!soft_dirty_open_files()) GC_incremental = FALSE; } # endif /* CAN_HANDLE_FORK */ /* Clear soft-dirty bits from the task's PTEs. */ static void clear_soft_dirty_bits(void) { ssize_t res = write(clear_refs_fd, "4\n", 2); if (res != 2) ABORT_ARG1("Failed to write to /proc/self/clear_refs", ": errno= %d", res < 0 ? errno : 0); } /* The bit 55 of the 64-bit `qword` of `pagemap` file is the soft-dirty one. */ # define PM_SOFTDIRTY_MASK ((pagemap_elem_t)1 << 55) static GC_bool detect_soft_dirty_supported(ptr_t vaddr) { off_t fpos; pagemap_elem_t buf[1]; GC_ASSERT(GC_log_pagesize != 0); /* Make it dirty. */ *vaddr = 1; fpos = (off_t)((ADDR(vaddr) >> GC_log_pagesize) * sizeof(pagemap_elem_t)); for (;;) { /* Read the relevant PTE from the `pagemap` file. */ if (lseek(pagemap_fd, fpos, SEEK_SET) == (off_t)(-1)) return FALSE; if (PROC_READ(pagemap_fd, buf, sizeof(buf)) != (int)sizeof(buf)) return FALSE; /* Is the soft-dirty bit unset? */ if ((buf[0] & PM_SOFTDIRTY_MASK) == 0) return FALSE; if (0 == *vaddr) break; /* * Retry to check that writing to `clear_refs` works as expected. * This malfunction of the soft-dirty bits implementation is * observed on some Linux kernels on Power9 (e.g. in Fedora 36). */ clear_soft_dirty_bits(); *vaddr = 0; } return TRUE; /*< success */ } # ifndef NO_SOFT_VDB_LINUX_VER_RUNTIME_CHECK # include /*< for strcmp() */ # include /* Ensure the linux (kernel) major/minor version is as given or higher. */ static GC_bool ensure_min_linux_ver(int major, int minor) { struct utsname info; int actual_major; int actual_minor = -1; if (uname(&info) == -1) { /* `uname()` has failed, should not happen actually. */ return FALSE; } if (strcmp(info.sysname, "Linux")) { WARN("Cannot ensure Linux version as running on other OS: %s\n", info.sysname); return FALSE; } actual_major = GC_parse_version(&actual_minor, info.release); return actual_major > major || (actual_major == major && actual_minor >= minor); } # endif # ifdef MPROTECT_VDB static GC_bool soft_dirty_init(void) # else GC_INNER GC_bool GC_dirty_init(void) # endif { # if defined(MPROTECT_VDB) && !defined(CHECK_SOFT_VDB) char *str = GETENV("GC_USE_GETWRITEWATCH"); # ifdef GC_PREFER_MPROTECT_VDB if (NULL == str || (*str == '0' && *(str + 1) == '\0')) { /* The environment variable is unset or set to "0". */ return FALSE; } # else if (str != NULL && *str == '0' && *(str + 1) == '\0') { /* The environment variable is set "0". */ return FALSE; } # endif # endif GC_ASSERT(I_HOLD_LOCK()); GC_ASSERT(NULL == soft_vdb_buf); # ifndef NO_SOFT_VDB_LINUX_VER_RUNTIME_CHECK if (!ensure_min_linux_ver(3, 18)) { GC_COND_LOG_PRINTF( "Running on old kernel lacking correct soft-dirty bit support\n"); return FALSE; } # endif if (!soft_dirty_open_files()) return FALSE; soft_vdb_buf = (pagemap_elem_t *)GC_scratch_alloc(VDB_BUF_SZ); if (NULL == soft_vdb_buf) ABORT("Insufficient space for /proc pagemap buffer"); if (!detect_soft_dirty_supported((ptr_t)soft_vdb_buf)) { GC_COND_LOG_PRINTF("Soft-dirty bit is not supported by kernel\n"); /* Release the resources. */ GC_scratch_recycle_no_gww(soft_vdb_buf, VDB_BUF_SZ); soft_vdb_buf = NULL; close(clear_refs_fd); clear_refs_fd = -1; close(pagemap_fd); return FALSE; } return TRUE; } static off_t pagemap_buf_fpos; /*< valid only if `pagemap_buf_len > 0` */ static size_t pagemap_buf_len; /* * Read bytes from `/proc/self/pagemap` file at given file position. * `len` is the maximum number of bytes to read; `*pres` is the amount * of bytes actually read (always bigger than 0 but never exceeds `len`); * `next_fpos_hint` is the file position of the next bytes block to read * ahead if possible (0 means no information provided). */ static const pagemap_elem_t * pagemap_buffered_read(size_t *pres, off_t fpos, size_t len, off_t next_fpos_hint) { ssize_t res; size_t ofs; GC_ASSERT(GC_page_size != 0); GC_ASSERT(len > 0); if (pagemap_buf_fpos <= fpos && fpos < pagemap_buf_fpos + (off_t)pagemap_buf_len) { /* The requested data is already in the buffer. */ ofs = (size_t)(fpos - pagemap_buf_fpos); res = (ssize_t)(pagemap_buf_fpos + pagemap_buf_len - fpos); } else { off_t aligned_pos = fpos & ~(off_t)(GC_page_size < VDB_BUF_SZ ? GC_page_size - 1 : VDB_BUF_SZ - 1); for (;;) { size_t count; if ((0 == pagemap_buf_len || pagemap_buf_fpos + (off_t)pagemap_buf_len != aligned_pos) && lseek(pagemap_fd, aligned_pos, SEEK_SET) == (off_t)(-1)) ABORT_ARG2("Failed to lseek /proc/self/pagemap", ": offset= %lu, errno= %d", (unsigned long)fpos, errno); /* How much to read at once? */ ofs = (size_t)(fpos - aligned_pos); GC_ASSERT(ofs < VDB_BUF_SZ); if (next_fpos_hint > aligned_pos && next_fpos_hint - aligned_pos < VDB_BUF_SZ) { count = VDB_BUF_SZ; } else { count = len + ofs; if (count > VDB_BUF_SZ) count = VDB_BUF_SZ; } GC_ASSERT(count % sizeof(pagemap_elem_t) == 0); res = PROC_READ(pagemap_fd, soft_vdb_buf, count); if (res > (ssize_t)ofs) break; if (res <= 0) ABORT_ARG1("Failed to read /proc/self/pagemap", ": errno= %d", res < 0 ? errno : 0); /* Retry (once) w/o page-alignment. */ aligned_pos = fpos; } /* Save the buffer (file window) position and size. */ pagemap_buf_fpos = aligned_pos; pagemap_buf_len = (size_t)res; res -= (ssize_t)ofs; } GC_ASSERT(ofs % sizeof(pagemap_elem_t) == 0); *pres = (size_t)res < len ? (size_t)res : len; return &soft_vdb_buf[ofs / sizeof(pagemap_elem_t)]; } static void soft_set_grungy_pages(ptr_t start, ptr_t limit, ptr_t next_start_hint, GC_bool is_static_root) { ptr_t vaddr = (ptr_t)HBLK_PAGE_ALIGNED(start); off_t next_fpos_hint = (off_t)((ADDR(next_start_hint) >> GC_log_pagesize) * sizeof(pagemap_elem_t)); GC_ASSERT(I_HOLD_LOCK()); GC_ASSERT(modHBLKSZ(ADDR(start)) == 0); GC_ASSERT(GC_log_pagesize != 0); while (ADDR_LT(vaddr, limit)) { size_t res; ptr_t limit_buf; word vlen_p = ADDR(limit) - ADDR(vaddr) + GC_page_size - 1; const pagemap_elem_t *bufp = pagemap_buffered_read( &res, (off_t)((ADDR(vaddr) >> GC_log_pagesize) * sizeof(pagemap_elem_t)), (size_t)((vlen_p >> GC_log_pagesize) * sizeof(pagemap_elem_t)), next_fpos_hint); if (res % sizeof(pagemap_elem_t) != 0) { /* Punt. */ memset(GC_grungy_pages, 0xff, sizeof(page_hash_table)); WARN("Incomplete read of pagemap, not multiple of entry size\n", 0); break; } limit_buf = vaddr + ((res / sizeof(pagemap_elem_t)) << GC_log_pagesize); for (; ADDR_LT(vaddr, limit_buf); vaddr += GC_page_size, bufp++) { if ((*bufp & PM_SOFTDIRTY_MASK) != 0) { struct hblk *h; ptr_t next_vaddr = vaddr + GC_page_size; if (UNLIKELY(ADDR_LT(limit, next_vaddr))) { next_vaddr = limit; } /* * If the bit is set, the respective PTE was written to * since clearing the soft-dirty bits. */ # ifdef DEBUG_DIRTY_BITS if (is_static_root) GC_log_printf("static root dirty page at: %p\n", (void *)vaddr); # endif h = (struct hblk *)vaddr; if (UNLIKELY(ADDR_LT(vaddr, start))) { h = (struct hblk *)start; } for (; ADDR_LT((ptr_t)h, next_vaddr); h++) { size_t index = PHT_HASH(h); /* * Filter out the blocks without pointers. It might worth for * the case when the heap is large enough for the hash collisions * to occur frequently. Thus, off by default. */ # if defined(FILTER_PTRFREE_HBLKS_IN_SOFT_VDB) || defined(CHECKSUMS) \ || defined(DEBUG_DIRTY_BITS) if (!is_static_root) { hdr *hhdr; # ifdef CHECKSUMS set_pht_entry_from_index(GC_written_pages, index); # endif GET_HDR(h, hhdr); if (NULL == hhdr) continue; (void)GC_find_starting_hblk(h, &hhdr); if (HBLK_IS_FREE(hhdr) || IS_PTRFREE(hhdr)) continue; # ifdef DEBUG_DIRTY_BITS GC_log_printf("dirty page (hblk) at: %p\n", (void *)h); # endif } # else UNUSED_ARG(is_static_root); # endif set_pht_entry_from_index(GC_grungy_pages, index); } } else { # if defined(CHECK_SOFT_VDB) /* `&& defined(MPROTECT_VDB)` */ /* * Ensure that each clean page according to the soft-dirty VDB is * also identified such by the `mprotect`-based one. */ if (!is_static_root && get_pht_entry_from_index(GC_dirty_pages, PHT_HASH(vaddr))) { ptr_t my_start, my_end; /*< the values are not used */ /* * There could be a hash collision, thus we need to verify the * page is clean using slow `GC_get_maps()`. */ if (GC_enclosing_writable_mapping(vaddr, &my_start, &my_end)) { ABORT("Inconsistent soft-dirty against mprotect dirty bits"); } } # endif } } /* Read the next portion of `pagemap` file if incomplete. */ } } GC_INLINE void GC_soft_read_dirty(GC_bool output_unneeded) { GC_ASSERT(I_HOLD_LOCK()); # ifndef THREADS /* Similar as for `GC_proc_read_dirty`. */ if (getpid() != saved_proc_pid && (-1 == clear_refs_fd /*< no need to retry */ || (close(clear_refs_fd), close(pagemap_fd), !soft_dirty_open_files()))) { /* Failed to reopen the files. */ if (!output_unneeded) { /* Punt. */ memset(GC_grungy_pages, 0xff, sizeof(page_hash_table)); # ifdef CHECKSUMS memset(GC_written_pages, 0xff, sizeof(page_hash_table)); # endif } return; } # endif if (!output_unneeded) { size_t i; BZERO(GC_grungy_pages, sizeof(GC_grungy_pages)); pagemap_buf_len = 0; /*< invalidate `soft_vdb_buf` */ for (i = 0; i < GC_n_heap_sects; ++i) { ptr_t start = GC_heap_sects[i].hs_start; soft_set_grungy_pages( start, start + GC_heap_sects[i].hs_bytes, i + 1 < GC_n_heap_sects ? GC_heap_sects[i + 1].hs_start : NULL, FALSE); } # ifndef NO_VDB_FOR_STATIC_ROOTS for (i = 0; i < n_root_sets; ++i) { soft_set_grungy_pages( (ptr_t)HBLKPTR(GC_static_roots[i].r_start), GC_static_roots[i].r_end, i + 1 < n_root_sets ? GC_static_roots[i + 1].r_start : NULL, TRUE); } # endif } clear_soft_dirty_bits(); } #endif /* SOFT_VDB */ #ifndef NO_MANUAL_VDB GC_INNER GC_bool GC_manual_vdb = FALSE; void GC_dirty_inner(const void *p) { size_t index = PHT_HASH(p); # if defined(MPROTECT_VDB) /* * Do not update `GC_dirty_pages` if it should be followed by the * page unprotection. */ GC_ASSERT(GC_manual_vdb); # endif async_set_pht_entry_from_index(GC_dirty_pages, index); } #endif /* !NO_MANUAL_VDB */ #ifndef GC_DISABLE_INCREMENTAL GC_INNER void GC_read_dirty(GC_bool output_unneeded) { GC_ASSERT(I_HOLD_LOCK()); # ifdef DEBUG_DIRTY_BITS GC_log_printf("read dirty begin\n"); # endif if (GC_manual_vdb # if defined(MPROTECT_VDB) || !GC_GWW_AVAILABLE() # endif ) { if (!output_unneeded) BCOPY(CAST_AWAY_VOLATILE_PVOID(GC_dirty_pages), GC_grungy_pages, sizeof(GC_dirty_pages)); BZERO(CAST_AWAY_VOLATILE_PVOID(GC_dirty_pages), sizeof(GC_dirty_pages)); # ifdef MPROTECT_VDB if (!GC_manual_vdb) GC_protect_heap(); # endif return; } # ifdef GWW_VDB GC_gww_read_dirty(output_unneeded); # elif defined(PROC_VDB) GC_proc_read_dirty(output_unneeded); # elif defined(SOFT_VDB) GC_soft_read_dirty(output_unneeded); # endif # if defined(CHECK_SOFT_VDB) /* `&& defined(MPROTECT_VDB)` */ BZERO(CAST_AWAY_VOLATILE_PVOID(GC_dirty_pages), sizeof(GC_dirty_pages)); GC_protect_heap(); # endif } # if !defined(NO_VDB_FOR_STATIC_ROOTS) && !defined(PROC_VDB) GC_INNER GC_bool GC_is_vdb_for_static_roots(void) { if (GC_manual_vdb) return FALSE; # if defined(MPROTECT_VDB) /* Currently used only in conjunction with `SOFT_VDB`. */ return GC_GWW_AVAILABLE(); # else # ifndef LINT2 GC_ASSERT(GC_incremental); # endif return TRUE; # endif } # endif GC_INNER GC_bool GC_page_was_dirty(struct hblk *h) { size_t index; # ifdef DEFAULT_VDB if (!GC_manual_vdb) return TRUE; # elif defined(PROC_VDB) /* Unless manual VDB is on, the bitmap covers all process memory. */ if (GC_manual_vdb) # endif { if (NULL == HDR(h)) return TRUE; } index = PHT_HASH(h); return get_pht_entry_from_index(GC_grungy_pages, index); } # if defined(CHECKSUMS) || defined(PROC_VDB) GC_INNER GC_bool GC_page_was_ever_dirty(struct hblk *h) { # if defined(GWW_VDB) || defined(PROC_VDB) || defined(SOFT_VDB) size_t index; # ifdef MPROTECT_VDB if (!GC_GWW_AVAILABLE()) return TRUE; # endif # if defined(PROC_VDB) if (GC_manual_vdb) # endif { if (NULL == HDR(h)) return TRUE; } index = PHT_HASH(h); return get_pht_entry_from_index(GC_written_pages, index); # else /* TODO: Implement for `MANUAL_VDB` case. */ UNUSED_ARG(h); return TRUE; # endif } # endif /* CHECKSUMS || PROC_VDB */ GC_INNER void GC_remove_protection(struct hblk *h, size_t nblocks, GC_bool is_ptrfree) { # ifdef MPROTECT_VDB struct hblk *current; struct hblk *h_trunc; /*< truncated to page boundary */ ptr_t h_end; /*< page boundary following the block end */ # endif # ifndef PARALLEL_MARK GC_ASSERT(I_HOLD_LOCK()); # endif # ifdef MPROTECT_VDB /* * Note it is not allowed to call `GC_printf` (and the friends) * in this function, see Win32 `GC_stop_world` for the details. */ # ifdef DONT_PROTECT_PTRFREE if (is_ptrfree) return; # endif if (!GC_auto_incremental || GC_GWW_AVAILABLE()) return; GC_ASSERT(GC_page_size != 0); h_trunc = HBLK_PAGE_ALIGNED(h); h_end = PTR_ALIGN_UP((ptr_t)(h + nblocks), GC_page_size); /* * Note that we cannot examine `GC_dirty_pages` to check whether the * page at `h_trunc` has already been marked dirty as there could be * a hash collision. */ for (current = h_trunc; ADDR_LT((ptr_t)current, h_end); ++current) { size_t index = PHT_HASH(current); # ifndef DONT_PROTECT_PTRFREE if (!is_ptrfree || !ADDR_INSIDE((ptr_t)current, (ptr_t)h, (ptr_t)(h + nblocks))) # endif { async_set_pht_entry_from_index(GC_dirty_pages, index); } } UNPROTECT(h_trunc, h_end - (ptr_t)h_trunc); # else /* Ignore write hints. They do not help us here. */ UNUSED_ARG(h); UNUSED_ARG(nblocks); UNUSED_ARG(is_ptrfree); # endif } #endif /* !GC_DISABLE_INCREMENTAL */ #if defined(MPROTECT_VDB) && defined(DARWIN) /* * The following sources were used as a "reference" for this exception * handling code: * - Apple's mach/xnu documentation; * - Timothy J. Wood's "Mach Exception Handlers 101" post to the omnigroup's * macosx-dev list; * - macosx-nat.c from Apple's GDB source code. */ /* * The bug that caused all this trouble should now be fixed. * This should eventually be removed if all goes well. */ # include # include # include # include EXTERN_C_BEGIN /* * Some of the following prototypes are missing in any header, although * they are documented. Some are in platform `mach/exc.h` file. */ extern boolean_t exc_server(mach_msg_header_t *, mach_msg_header_t *); extern kern_return_t exception_raise(mach_port_t, mach_port_t, mach_port_t, exception_type_t, exception_data_t, mach_msg_type_number_t); extern kern_return_t exception_raise_state( mach_port_t, mach_port_t, mach_port_t, exception_type_t, exception_data_t, mach_msg_type_number_t, thread_state_flavor_t *, thread_state_t, mach_msg_type_number_t, thread_state_t, mach_msg_type_number_t *); extern kern_return_t exception_raise_state_identity( mach_port_t, mach_port_t, mach_port_t, exception_type_t, exception_data_t, mach_msg_type_number_t, thread_state_flavor_t *, thread_state_t, mach_msg_type_number_t, thread_state_t, mach_msg_type_number_t *); GC_API_OSCALL kern_return_t catch_exception_raise( mach_port_t exception_port, mach_port_t thread, mach_port_t task, exception_type_t exception, exception_data_t code, mach_msg_type_number_t code_count); GC_API_OSCALL kern_return_t catch_exception_raise_state( mach_port_name_t exception_port, int exception, exception_data_t code, mach_msg_type_number_t codeCnt, int flavor, thread_state_t old_state, int old_stateCnt, thread_state_t new_state, int new_stateCnt); GC_API_OSCALL kern_return_t catch_exception_raise_state_identity( mach_port_name_t exception_port, mach_port_t thread, mach_port_t task, int exception, exception_data_t code, mach_msg_type_number_t codeCnt, int flavor, thread_state_t old_state, int old_stateCnt, thread_state_t new_state, int new_stateCnt); EXTERN_C_END /* These should never be called, but just in case... */ GC_API_OSCALL kern_return_t catch_exception_raise_state(mach_port_name_t exception_port, int exception, exception_data_t code, mach_msg_type_number_t codeCnt, int flavor, thread_state_t old_state, int old_stateCnt, thread_state_t new_state, int new_stateCnt) { UNUSED_ARG(exception_port); UNUSED_ARG(exception); UNUSED_ARG(code); UNUSED_ARG(codeCnt); UNUSED_ARG(flavor); UNUSED_ARG(old_state); UNUSED_ARG(old_stateCnt); UNUSED_ARG(new_state); UNUSED_ARG(new_stateCnt); ABORT_RET("Unexpected catch_exception_raise_state invocation"); return KERN_INVALID_ARGUMENT; } GC_API_OSCALL kern_return_t catch_exception_raise_state_identity( mach_port_name_t exception_port, mach_port_t thread, mach_port_t task, int exception, exception_data_t code, mach_msg_type_number_t codeCnt, int flavor, thread_state_t old_state, int old_stateCnt, thread_state_t new_state, int new_stateCnt) { UNUSED_ARG(exception_port); UNUSED_ARG(thread); UNUSED_ARG(task); UNUSED_ARG(exception); UNUSED_ARG(code); UNUSED_ARG(codeCnt); UNUSED_ARG(flavor); UNUSED_ARG(old_state); UNUSED_ARG(old_stateCnt); UNUSED_ARG(new_state); UNUSED_ARG(new_stateCnt); ABORT_RET("Unexpected catch_exception_raise_state_identity invocation"); return KERN_INVALID_ARGUMENT; } # define MAX_EXCEPTION_PORTS 16 static struct { mach_msg_type_number_t count; exception_mask_t masks[MAX_EXCEPTION_PORTS]; exception_handler_t ports[MAX_EXCEPTION_PORTS]; exception_behavior_t behaviors[MAX_EXCEPTION_PORTS]; thread_state_flavor_t flavors[MAX_EXCEPTION_PORTS]; } GC_old_exc_ports; STATIC struct ports_s { void (*volatile os_callback[3])(void); mach_port_t exception; # if defined(THREADS) mach_port_t reply; # endif } GC_ports = { { /*< this is to prevent stripping these routines as dead */ (void (*)(void))catch_exception_raise, (void (*)(void))catch_exception_raise_state, (void (*)(void))catch_exception_raise_state_identity }, # ifdef THREADS 0 /* `exception` */, # endif 0 }; typedef struct { mach_msg_header_t head; } GC_msg_t; typedef enum { GC_MP_NORMAL, GC_MP_DISCARDING, GC_MP_STOPPED } GC_mprotect_state_t; # ifdef THREADS /* * FIXME: 1 and 2 seem to be safe to use in the `msgh_id` field, but it * is not documented. Use the source and see if they should be OK. */ # define ID_STOP 1 # define ID_RESUME 2 /* This value is only used on the reply port. */ # define ID_ACK 3 STATIC GC_mprotect_state_t GC_mprotect_state = GC_MP_NORMAL; /* The following should *only* be called when the world is stopped. */ STATIC void GC_mprotect_thread_notify(mach_msg_id_t id) { struct buf_s { GC_msg_t msg; mach_msg_trailer_t trailer; } buf; mach_msg_return_t r; /* remote, local */ buf.msg.head.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND, 0); buf.msg.head.msgh_size = sizeof(buf.msg); buf.msg.head.msgh_remote_port = GC_ports.exception; buf.msg.head.msgh_local_port = MACH_PORT_NULL; buf.msg.head.msgh_id = id; r = mach_msg(&buf.msg.head, MACH_SEND_MSG | MACH_RCV_MSG | MACH_RCV_LARGE, sizeof(buf.msg), sizeof(buf), GC_ports.reply, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); if (r != MACH_MSG_SUCCESS) ABORT("mach_msg failed in GC_mprotect_thread_notify"); if (buf.msg.head.msgh_id != ID_ACK) ABORT("Invalid ack in GC_mprotect_thread_notify"); } /* Should only be called by the `mprotect` thread. */ STATIC void GC_mprotect_thread_reply(void) { GC_msg_t msg; mach_msg_return_t r; /* remote, local */ msg.head.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND, 0); msg.head.msgh_size = sizeof(msg); msg.head.msgh_remote_port = GC_ports.reply; msg.head.msgh_local_port = MACH_PORT_NULL; msg.head.msgh_id = ID_ACK; r = mach_msg(&msg.head, MACH_SEND_MSG, sizeof(msg), 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); if (r != MACH_MSG_SUCCESS) ABORT("mach_msg failed in GC_mprotect_thread_reply"); } GC_INNER void GC_mprotect_stop(void) { GC_mprotect_thread_notify(ID_STOP); } GC_INNER void GC_mprotect_resume(void) { GC_mprotect_thread_notify(ID_RESUME); } # ifdef CAN_HANDLE_FORK GC_INNER void GC_dirty_update_child(void) { GC_ASSERT(I_HOLD_LOCK()); if (0 == GC_task_self) { /* The GC incremental mode is off. */ return; } GC_ASSERT(GC_mprotect_state == GC_MP_NORMAL); GC_task_self = mach_task_self(); /*< needed by `UNPROTECT()` */ GC_unprotect_all_heap(); /* Restore the old task exception ports. */ /* TODO: Should we do it in `fork_prepare_proc`/`fork_parent_proc`? */ if (GC_old_exc_ports.count > 0) { /* TODO: Should we check `GC_old_exc_ports.count <= 1`? */ if (task_set_exception_ports( GC_task_self, GC_old_exc_ports.masks[0], GC_old_exc_ports.ports[0], GC_old_exc_ports.behaviors[0], GC_old_exc_ports.flavors[0]) != KERN_SUCCESS) ABORT("task_set_exception_ports failed (in child)"); } /* TODO: Re-enable incremental mode in child. */ GC_task_self = 0; GC_incremental = FALSE; } # endif /* CAN_HANDLE_FORK */ # else /* The compiler should optimize away any `GC_mprotect_state` computations. */ # define GC_mprotect_state GC_MP_NORMAL # endif /* !THREADS */ struct mp_reply_s { mach_msg_header_t head; char data[256]; }; struct mp_msg_s { mach_msg_header_t head; mach_msg_body_t msgh_body; char data[1024]; }; STATIC void * GC_mprotect_thread(void *arg) { mach_msg_return_t r; /* * These two structures contain some private kernel data. We do not need * to access any of it so we do not bother defining a proper structure. * The correct definitions are in the `xnu` source code. */ struct mp_reply_s reply; struct mp_msg_s msg; mach_msg_id_t id; if (ADDR(arg) == GC_WORD_MAX) return 0; /*< to prevent a compiler warning */ # if defined(CPPCHECK) reply.data[0] = 0; /*< to prevent "field unused" warnings */ msg.data[0] = 0; # endif # if defined(HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID) (void)pthread_setname_np("GC-mprotect"); # endif # if defined(THREADS) && !defined(GC_NO_THREADS_DISCOVERY) GC_darwin_register_self_mach_handler(); # endif for (;;) { r = mach_msg( &msg.head, MACH_RCV_MSG | MACH_RCV_LARGE | (GC_mprotect_state == GC_MP_DISCARDING ? MACH_RCV_TIMEOUT : 0), 0, sizeof(msg), GC_ports.exception, GC_mprotect_state == GC_MP_DISCARDING ? 0 : MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); id = r == MACH_MSG_SUCCESS ? msg.head.msgh_id : -1; # if defined(THREADS) if (GC_mprotect_state == GC_MP_DISCARDING) { if (r == MACH_RCV_TIMED_OUT) { GC_mprotect_state = GC_MP_STOPPED; GC_mprotect_thread_reply(); continue; } if (r == MACH_MSG_SUCCESS && (id == ID_STOP || id == ID_RESUME)) ABORT("Out of order mprotect thread request"); } # endif /* THREADS */ if (r != MACH_MSG_SUCCESS) { ABORT_ARG2("mach_msg failed", ": errcode= %d (%s)", (int)r, mach_error_string(r)); } switch (id) { # if defined(THREADS) case ID_STOP: if (GC_mprotect_state != GC_MP_NORMAL) ABORT("Called mprotect_stop when state wasn't normal"); GC_mprotect_state = GC_MP_DISCARDING; break; case ID_RESUME: if (GC_mprotect_state != GC_MP_STOPPED) ABORT("Called mprotect_resume when state wasn't stopped"); GC_mprotect_state = GC_MP_NORMAL; GC_mprotect_thread_reply(); break; # endif /* THREADS */ default: /* Handle the message (it calls `catch_exception_raise`). */ if (!exc_server(&msg.head, &reply.head)) ABORT("exc_server failed"); /* Send the reply. */ r = mach_msg(&reply.head, MACH_SEND_MSG, reply.head.msgh_size, 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); if (r != MACH_MSG_SUCCESS) { /* * This will fail if the thread dies, but the thread should * not die... */ # ifdef BROKEN_EXCEPTION_HANDLING GC_err_printf("mach_msg failed with %d %s while sending " "exc reply\n", (int)r, mach_error_string(r)); # else ABORT("mach_msg failed while sending exception reply"); # endif } } } } /* * All this `SIGBUS` code should not be necessary. All protection * faults should be going through the `mach` exception handler. * However, it seems a `SIGBUS` is occasionally sent for some unknown * reason; even more odd, it seems to be meaningless and safe to ignore. */ # ifdef BROKEN_EXCEPTION_HANDLING /* * Updates to this are not atomic, but the `SIGBUS` signals seem pretty rare. * Even if this does not get updated property, it is not really a problem. */ STATIC int GC_sigbus_count = 0; STATIC void GC_darwin_sigbus(int num, siginfo_t *sip, void *context) { if (num != SIGBUS) ABORT("Got a non-sigbus signal in the sigbus handler"); /* * Ugh... some seem safe to ignore, but too many in a row probably means * trouble. `GC_sigbus_count` is reset for each `mach` exception that * is handled. */ if (GC_sigbus_count >= 8) ABORT("Got many SIGBUS signals in a row!"); GC_sigbus_count++; WARN("Ignoring SIGBUS\n", 0); } # endif /* BROKEN_EXCEPTION_HANDLING */ GC_INNER GC_bool GC_dirty_init(void) { kern_return_t r; mach_port_t me; pthread_t thread; pthread_attr_t attr; exception_mask_t mask; GC_ASSERT(I_HOLD_LOCK()); # if defined(CAN_HANDLE_FORK) && !defined(THREADS) if (GC_handle_fork) { /* * To both support GC incremental mode and GC functions usage in * the forked child process, `pthread_atfork` should be used to * install handlers that switch off `GC_incremental` in the child * gracefully (unprotecting all pages and clearing * `GC_mach_handler_thread`). For now, we just disable incremental * mode if `fork()` handling is requested by the client. */ WARN("Can't turn on GC incremental mode as fork()" " handling requested\n", 0); return FALSE; } # endif GC_VERBOSE_LOG_PRINTF("Initializing mach/darwin mprotect" " virtual dirty bit implementation\n"); # ifdef BROKEN_EXCEPTION_HANDLING WARN("Enabling workarounds for various darwin exception handling bugs\n", 0); # endif if (GC_page_size % HBLKSIZE != 0) { ABORT("Page size not multiple of HBLKSIZE"); } GC_task_self = me = mach_task_self(); GC_ASSERT(me != 0); r = mach_port_allocate(me, MACH_PORT_RIGHT_RECEIVE, &GC_ports.exception); /* TODO: Call `WARN()` and return `FALSE` in case of a failure. */ if (r != KERN_SUCCESS) ABORT("mach_port_allocate failed (exception port)"); r = mach_port_insert_right(me, GC_ports.exception, GC_ports.exception, MACH_MSG_TYPE_MAKE_SEND); if (r != KERN_SUCCESS) ABORT("mach_port_insert_right failed (exception port)"); # if defined(THREADS) r = mach_port_allocate(me, MACH_PORT_RIGHT_RECEIVE, &GC_ports.reply); if (r != KERN_SUCCESS) ABORT("mach_port_allocate failed (reply port)"); # endif /* The exceptions we want to catch. */ mask = EXC_MASK_BAD_ACCESS; r = task_get_exception_ports(me, mask, GC_old_exc_ports.masks, &GC_old_exc_ports.count, GC_old_exc_ports.ports, GC_old_exc_ports.behaviors, GC_old_exc_ports.flavors); if (r != KERN_SUCCESS) ABORT("task_get_exception_ports failed"); r = task_set_exception_ports(me, mask, GC_ports.exception, EXCEPTION_DEFAULT, GC_MACH_THREAD_STATE); if (r != KERN_SUCCESS) ABORT("task_set_exception_ports failed"); if (pthread_attr_init(&attr) != 0) ABORT("pthread_attr_init failed"); if (pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) != 0) ABORT("pthread_attr_setdetachedstate failed"); /* This will call the real `pthreads` routine, not our wrapper. */ if (GC_inner_pthread_create(&thread, &attr, GC_mprotect_thread, NULL) != 0) ABORT("pthread_create failed"); (void)pthread_attr_destroy(&attr); /* Setup the handler for ignoring the meaningless `SIGBUS` signals. */ # ifdef BROKEN_EXCEPTION_HANDLING { struct sigaction sa, oldsa; sa.sa_handler = (SIG_HNDLR_PTR)GC_darwin_sigbus; sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART | SA_SIGINFO; /* `sa.sa_restorer` is deprecated and should not be initialized. */ if (sigaction(SIGBUS, &sa, &oldsa) < 0) ABORT("sigaction failed"); if ((GC_funcptr_uint)oldsa.sa_handler != (GC_funcptr_uint)SIG_DFL) { GC_VERBOSE_LOG_PRINTF("Replaced other SIGBUS handler\n"); } } # endif /* BROKEN_EXCEPTION_HANDLING */ # if defined(CPPCHECK) GC_noop1((word)(GC_funcptr_uint)GC_ports.os_callback[0]); # endif return TRUE; } /* * The source code for Apple's GDB was used as a reference for the * exception forwarding code. This code is similar to be GDB code only * because there is only one way to do it. */ STATIC kern_return_t GC_forward_exception(mach_port_t thread, mach_port_t task, exception_type_t exception, exception_data_t data, mach_msg_type_number_t data_count) { size_t i; kern_return_t r; mach_port_t port; exception_behavior_t behavior; thread_state_flavor_t flavor; thread_state_data_t thread_state; mach_msg_type_number_t thread_state_count = THREAD_STATE_MAX; for (i = 0; i < (size_t)GC_old_exc_ports.count; i++) { if ((GC_old_exc_ports.masks[i] & ((exception_mask_t)1 << exception)) != 0) break; } if (i == (size_t)GC_old_exc_ports.count) ABORT("No handler for exception!"); port = GC_old_exc_ports.ports[i]; behavior = GC_old_exc_ports.behaviors[i]; flavor = GC_old_exc_ports.flavors[i]; if (behavior == EXCEPTION_STATE || behavior == EXCEPTION_STATE_IDENTITY) { r = thread_get_state(thread, flavor, thread_state, &thread_state_count); if (r != KERN_SUCCESS) ABORT("thread_get_state failed in forward_exception"); } switch (behavior) { case EXCEPTION_STATE: r = exception_raise_state(port, thread, task, exception, data, data_count, &flavor, thread_state, thread_state_count, thread_state, &thread_state_count); break; case EXCEPTION_STATE_IDENTITY: r = exception_raise_state_identity( port, thread, task, exception, data, data_count, &flavor, thread_state, thread_state_count, thread_state, &thread_state_count); break; /* `case EXCEPTION_DEFAULT:` - the default signal handlers. */ default: /* The user-supplied signal handlers. */ r = exception_raise(port, thread, task, exception, data, data_count); } if (behavior == EXCEPTION_STATE || behavior == EXCEPTION_STATE_IDENTITY) { r = thread_set_state(thread, flavor, thread_state, thread_state_count); if (r != KERN_SUCCESS) ABORT("thread_set_state failed in forward_exception"); } return r; } # define FWD() GC_forward_exception(thread, task, exception, code, code_count) # ifdef ARM32 # define DARWIN_EXC_STATE ARM_EXCEPTION_STATE # define DARWIN_EXC_STATE_COUNT ARM_EXCEPTION_STATE_COUNT # define DARWIN_EXC_STATE_T arm_exception_state_t # define DARWIN_EXC_STATE_DAR THREAD_FLD_NAME(far) # elif defined(AARCH64) # define DARWIN_EXC_STATE ARM_EXCEPTION_STATE64 # define DARWIN_EXC_STATE_COUNT ARM_EXCEPTION_STATE64_COUNT # define DARWIN_EXC_STATE_T arm_exception_state64_t # define DARWIN_EXC_STATE_DAR THREAD_FLD_NAME(far) # elif defined(POWERPC) # if CPP_WORDSZ == 32 # define DARWIN_EXC_STATE PPC_EXCEPTION_STATE # define DARWIN_EXC_STATE_COUNT PPC_EXCEPTION_STATE_COUNT # define DARWIN_EXC_STATE_T ppc_exception_state_t # else # define DARWIN_EXC_STATE PPC_EXCEPTION_STATE64 # define DARWIN_EXC_STATE_COUNT PPC_EXCEPTION_STATE64_COUNT # define DARWIN_EXC_STATE_T ppc_exception_state64_t # endif # define DARWIN_EXC_STATE_DAR THREAD_FLD_NAME(dar) # elif defined(I386) || defined(X86_64) # if CPP_WORDSZ == 32 # if defined(i386_EXCEPTION_STATE_COUNT) \ && !defined(x86_EXCEPTION_STATE32_COUNT) /* Use old naming convention for i686. */ # define DARWIN_EXC_STATE i386_EXCEPTION_STATE # define DARWIN_EXC_STATE_COUNT i386_EXCEPTION_STATE_COUNT # define DARWIN_EXC_STATE_T i386_exception_state_t # else # define DARWIN_EXC_STATE x86_EXCEPTION_STATE32 # define DARWIN_EXC_STATE_COUNT x86_EXCEPTION_STATE32_COUNT # define DARWIN_EXC_STATE_T x86_exception_state32_t # endif # else # define DARWIN_EXC_STATE x86_EXCEPTION_STATE64 # define DARWIN_EXC_STATE_COUNT x86_EXCEPTION_STATE64_COUNT # define DARWIN_EXC_STATE_T x86_exception_state64_t # endif # define DARWIN_EXC_STATE_DAR THREAD_FLD_NAME(faultvaddr) # elif !defined(CPPCHECK) # error FIXME for non-arm/ppc/x86 darwin # endif /* * This violates the namespace rules but there is not anything that can * be done about it. The exception handling stuff is hard-coded to * call this. `catch_exception_raise`, `catch_exception_raise_state` * and `catch_exception_raise_state_identity` are called from OS. */ GC_API_OSCALL kern_return_t catch_exception_raise(mach_port_t exception_port, mach_port_t thread, mach_port_t task, exception_type_t exception, exception_data_t code, mach_msg_type_number_t code_count) { kern_return_t r; char *addr; thread_state_flavor_t flavor = DARWIN_EXC_STATE; mach_msg_type_number_t exc_state_count = DARWIN_EXC_STATE_COUNT; DARWIN_EXC_STATE_T exc_state; UNUSED_ARG(exception_port); UNUSED_ARG(task); if (exception != EXC_BAD_ACCESS || code[0] != KERN_PROTECTION_FAILURE) { # ifdef DEBUG_EXCEPTION_HANDLING /* We are not interested in, pass it on to the old handler. */ GC_log_printf("Exception: 0x%x Code: 0x%x 0x%x in catch...\n", exception, code_count > 0 ? code[0] : -1, code_count > 1 ? code[1] : -1); # else UNUSED_ARG(code_count); # endif return FWD(); } r = thread_get_state(thread, flavor, (natural_t *)&exc_state, &exc_state_count); if (r != KERN_SUCCESS) { /* * The thread is supposed to be suspended while the exception * handler is called. This should not fail. */ # ifdef BROKEN_EXCEPTION_HANDLING GC_err_printf("thread_get_state failed in catch_exception_raise\n"); return KERN_SUCCESS; # else ABORT("thread_get_state failed in catch_exception_raise"); # endif } /* This is the address that caused the fault. */ addr = (char *)exc_state.DARWIN_EXC_STATE_DAR; if (!is_header_found_async(addr)) { /* * Ugh... just like the `SIGBUS` problem above, it seems we get * a bogus `KERN_PROTECTION_FAILURE` every once and a while. * We wait till we get a bunch in a row before doing anything * about it. If a "real" fault ever occurs, it will just keep * faulting over and over, and we will hit the limit pretty quickly. */ # ifdef BROKEN_EXCEPTION_HANDLING static const char *last_fault; static int last_fault_count; if (addr != last_fault) { last_fault = addr; last_fault_count = 0; } if (++last_fault_count < 32) { if (last_fault_count == 1) WARN("Ignoring KERN_PROTECTION_FAILURE at %p\n", addr); return KERN_SUCCESS; } GC_err_printf("Unexpected KERN_PROTECTION_FAILURE at %p; aborting...\n", (void *)addr); /* * Cannot pass it along to the signal handler because that is ignoring * `SIGBUS` signals. We also should not call `ABORT()` here as signals * do not always work too well from the exception handler. */ EXIT(); # else /* * Pass it along to the next exception handler (which should call * `SIGBUS`/`SIGSEGV`). */ return FWD(); # endif /* !BROKEN_EXCEPTION_HANDLING */ } # ifdef BROKEN_EXCEPTION_HANDLING /* Reset the number of consecutive `SIGBUS` signals. */ GC_sigbus_count = 0; # endif GC_ASSERT(GC_page_size != 0); if (GC_mprotect_state == GC_MP_NORMAL) { /* The common case. */ struct hblk *h = HBLK_PAGE_ALIGNED(addr); size_t i; # ifdef CHECKSUMS GC_record_fault(h); # endif UNPROTECT(h, GC_page_size); for (i = 0; i < divHBLKSZ(GC_page_size); i++) { size_t index = PHT_HASH(h + i); async_set_pht_entry_from_index(GC_dirty_pages, index); } } else if (GC_mprotect_state == GC_MP_DISCARDING) { /* * Lie to the thread for now. No sense `UNPROTECT`'ing the memory * when we are just going to `PROTECT()` it again later. * The thread will just fault again once it resumes. */ } else { /* Should not happen, I do not think. */ GC_err_printf("KERN_PROTECTION_FAILURE while world is stopped\n"); return FWD(); } return KERN_SUCCESS; } # undef FWD # ifndef NO_DESC_CATCH_EXCEPTION_RAISE /* * These symbols should have `REFERENCED_DYNAMICALLY` (0x10) bit set to * let strip know they are not to be stripped. */ __asm__(".desc _catch_exception_raise, 0x10"); __asm__(".desc _catch_exception_raise_state, 0x10"); __asm__(".desc _catch_exception_raise_state_identity, 0x10"); # endif #endif /* DARWIN && MPROTECT_VDB */ GC_API int GC_CALL GC_incremental_protection_needs(void) { GC_ASSERT(GC_is_initialized); #ifdef MPROTECT_VDB # if defined(GWW_VDB) || (defined(SOFT_VDB) && !defined(CHECK_SOFT_VDB)) /* Only if the incremental mode is already switched on. */ if (GC_GWW_AVAILABLE()) return GC_PROTECTS_NONE; # endif # ifndef DONT_PROTECT_PTRFREE if (GC_page_size != HBLKSIZE) return GC_PROTECTS_POINTER_HEAP | GC_PROTECTS_PTRFREE_HEAP; # endif return GC_PROTECTS_POINTER_HEAP; #else return GC_PROTECTS_NONE; #endif } GC_API unsigned GC_CALL GC_get_actual_vdb(void) { #ifndef GC_DISABLE_INCREMENTAL if (GC_incremental) { # ifndef NO_MANUAL_VDB if (GC_manual_vdb) return GC_VDB_MANUAL; # endif # ifdef MPROTECT_VDB # ifdef GWW_VDB if (GC_GWW_AVAILABLE()) return GC_VDB_GWW; # endif # ifdef SOFT_VDB if (GC_GWW_AVAILABLE()) return GC_VDB_SOFT; # endif return GC_VDB_MPROTECT; # elif defined(GWW_VDB) return GC_VDB_GWW; # elif defined(SOFT_VDB) return GC_VDB_SOFT; # elif defined(PROC_VDB) return GC_VDB_PROC; # else /* DEFAULT_VDB */ return GC_VDB_DEFAULT; # endif } #endif return GC_VDB_NONE; } #ifdef ECOS /* Undo `sbrk()` redirection. */ # undef sbrk #endif GC_API void GC_CALL GC_set_pages_executable(int value) { GC_ASSERT(!GC_is_initialized); /* * Even if `IGNORE_PAGES_EXECUTABLE` macro is defined, * `GC_pages_executable` is touched here to prevent a compiler warning. */ GC_pages_executable = (GC_bool)(value != 0); } GC_API int GC_CALL GC_get_pages_executable(void) { /* * `GC_get_pages_executable` is defined after all the places * where `GC_get_pages_executable` is undefined. */ #ifdef IGNORE_PAGES_EXECUTABLE /* Always allocate executable memory. */ return 1; #else return (int)GC_pages_executable; #endif } /* * Call stack save code for debugging. Should probably be in * `mach_dep.c` file, but that requires reorganization. */ #ifdef NEED_CALLINFO /* * I suspect the following works for most Un*x i686 variants, so long as * the frame pointer is explicitly stored. In the case of gcc, the client * code should not be compiled with `-fomit-frame-pointer` option. */ # if defined(I386) && defined(LINUX) && defined(SAVE_CALL_CHAIN) struct frame { struct frame *fr_savfp; long fr_savpc; # if NARGS > 0 /* All the arguments go here. */ long fr_arg[NARGS]; # endif }; # endif # if defined(SPARC) # if defined(LINUX) # if defined(SAVE_CALL_CHAIN) struct frame { long fr_local[8]; long fr_arg[6]; struct frame *fr_savfp; long fr_savpc; # ifndef __arch64__ char *fr_stret; # endif long fr_argd[6]; long fr_argx[0]; }; # endif # elif defined(DRSNX) # include # elif defined(OPENBSD) # include # elif defined(FREEBSD) || defined(NETBSD) # include # else # include # endif # if NARGS > 6 # error We only know how to get the first 6 arguments # endif # endif /* SPARC */ /* * Fill in the `pc` and `argument` information for up to `NFRAMES` of * my callers. Ignore my frame and my callers frame. */ # if defined(GC_HAVE_BUILTIN_BACKTRACE) # ifdef _MSC_VER EXTERN_C_BEGIN int backtrace(void *addresses[], int count); char **backtrace_symbols(void *const addresses[], int count); EXTERN_C_END # else # include # endif # endif /* GC_HAVE_BUILTIN_BACKTRACE */ # ifdef SAVE_CALL_CHAIN # if NARGS == 0 && NFRAMES % 2 == 0 /*< no padding */ \ && defined(GC_HAVE_BUILTIN_BACKTRACE) # ifdef REDIRECT_MALLOC /* * Deal with possible `malloc()` calls in `backtrace()` by omitting * the infinitely recursing backtrace. */ STATIC GC_bool GC_in_save_callers = FALSE; # if defined(THREADS) && defined(DBG_HDRS_ALL) # include "private/dbg_mlc.h" GC_INNER void GC_save_callers_no_unlock(struct callinfo info[NFRAMES]) { GC_ASSERT(I_HOLD_LOCK()); info[0].ci_pc = CAST_THRU_UINTPTR(GC_return_addr_t, GC_save_callers_no_unlock); BZERO(&info[1], sizeof(void *) * (NFRAMES - 1)); } # endif # endif /* REDIRECT_MALLOC */ GC_INNER void GC_save_callers(struct callinfo info[NFRAMES]) { void *tmp_info[NFRAMES + 1]; int npcs, i; /* * `backtrace()` may call `dl_iterate_phdr` which is also used by * `GC_register_dynamic_libraries()`, and `dl_iterate_phdr` is not * guaranteed to be reentrant. */ GC_ASSERT(I_HOLD_LOCK()); GC_STATIC_ASSERT(sizeof(struct callinfo) == sizeof(void *)); # ifdef REDIRECT_MALLOC if (GC_in_save_callers) { info[0].ci_pc = CAST_THRU_UINTPTR(GC_return_addr_t, GC_save_callers); BZERO(&info[1], sizeof(void *) * (NFRAMES - 1)); return; } GC_in_save_callers = TRUE; /* `backtrace()` might call a redirected `malloc`. */ UNLOCK(); npcs = backtrace((void **)tmp_info, NFRAMES + 1); LOCK(); # else npcs = backtrace((void **)tmp_info, NFRAMES + 1); # endif /* * We retrieve `NFRAMES + 1` `pc` values, but discard the first one, * since it points to our own frame. */ i = 0; if (npcs > 1) { i = npcs - 1; BCOPY(&tmp_info[1], info, (unsigned)i * sizeof(void *)); } BZERO(&info[i], sizeof(void *) * (unsigned)(NFRAMES - i)); # ifdef REDIRECT_MALLOC GC_in_save_callers = FALSE; # endif } # elif defined(I386) || defined(SPARC) # if defined(ANY_BSD) && defined(SPARC) # define FR_SAVFP fr_fp # define FR_SAVPC fr_pc # else # define FR_SAVFP fr_savfp # define FR_SAVPC fr_savpc # endif # if defined(SPARC) && (defined(__arch64__) || defined(__sparcv9)) # define BIAS 2047 # else # define BIAS 0 # endif GC_INNER void GC_save_callers(struct callinfo info[NFRAMES]) { struct frame *frame; struct frame *fp; int nframes = 0; # ifdef I386 /* We assume this is turned on only with gcc as the compiler. */ asm("movl %%ebp,%0" : "=r"(frame)); fp = frame; # else /* SPARC */ frame = (struct frame *)GC_save_regs_in_stack(); fp = (struct frame *)((ptr_t)frame->FR_SAVFP + BIAS); # endif for (; !HOTTER_THAN((ptr_t)fp, (ptr_t)frame) # ifndef THREADS && !HOTTER_THAN(GC_stackbottom, (ptr_t)fp) # elif defined(STACK_GROWS_UP) && fp != NULL # endif && nframes < NFRAMES; fp = (struct frame *)((ptr_t)fp->FR_SAVFP + BIAS), nframes++) { # if NARGS > 0 int i; # endif info[nframes].ci_pc = (GC_return_addr_t)fp->FR_SAVPC; # if NARGS > 0 for (i = 0; i < NARGS; i++) { info[nframes].ci_arg[i] = GC_HIDE_NZ_POINTER(MAKE_CPTR(fp->fr_arg[i])); } # endif } if (nframes < NFRAMES) info[nframes].ci_pc = 0; } # endif /* !GC_HAVE_BUILTIN_BACKTRACE */ # endif /* SAVE_CALL_CHAIN */ GC_INNER void GC_print_callers(struct callinfo info[NFRAMES]) { int i, reent_cnt; # if defined(AO_HAVE_fetch_and_add1) && defined(AO_HAVE_fetch_and_sub1) static volatile AO_t reentry_count = 0; /* * Note: alternatively, if available, we may use a thread-local storage, * thus, enabling concurrent usage of `GC_print_callers()`; * but practically this has little sense because printing is done into * a single output stream. */ GC_ASSERT(I_DONT_HOLD_LOCK()); reent_cnt = (int)(GC_signed_word)AO_fetch_and_add1(&reentry_count); # else static int reentry_count = 0; /* Note: this could use a different lock. */ LOCK(); reent_cnt = reentry_count++; UNLOCK(); # endif # if NFRAMES == 1 GC_err_printf("\tCaller at allocation:\n"); # else GC_err_printf("\tCall chain at allocation:\n"); # endif for (i = 0; i < NFRAMES; i++) { # if defined(LINUX) && !defined(SMALL_CONFIG) GC_bool stop = FALSE; # endif if (0 == info[i].ci_pc) break; # if NARGS > 0 { int j; GC_err_printf("\t\targs: "); for (j = 0; j < NARGS; j++) { void *p = GC_REVEAL_NZ_POINTER(info[i].ci_arg[j]); if (j != 0) GC_err_printf(", "); GC_err_printf("%ld (%p)", (long)(GC_signed_word)ADDR(p), p); } GC_err_printf("\n"); } # endif if (reent_cnt > 0) { /* * We were called either concurrently or during an allocation * by `backtrace_symbols()` called from `GC_print_callers`; punt. */ GC_err_printf("\t\t##PC##= 0x%lx\n", (unsigned long)ADDR(info[i].ci_pc)); continue; } { char buf[40]; char *name; # if defined(GC_HAVE_BUILTIN_BACKTRACE) \ && !defined(GC_BACKTRACE_SYMBOLS_BROKEN) && defined(FUNCPTR_IS_DATAPTR) char **sym_name = backtrace_symbols((void **)&info[i].ci_pc, 1); if (sym_name != NULL) { name = sym_name[0]; } else # endif /* else */ { (void)snprintf(buf, sizeof(buf), "##PC##= 0x%lx", (unsigned long)ADDR(info[i].ci_pc)); buf[sizeof(buf) - 1] = '\0'; name = buf; } # if defined(LINUX) && !defined(SMALL_CONFIG) /* Try for a line number. */ do { FILE *pipe; # define EXE_SZ 100 static char exe_name[EXE_SZ]; # define CMD_SZ 200 char cmd_buf[CMD_SZ]; # define RESULT_SZ 200 static char result_buf[RESULT_SZ]; size_t result_len; const char *old_preload; # define PRELOAD_SZ 200 char preload_buf[PRELOAD_SZ]; static GC_bool found_exe_name = FALSE; static GC_bool will_fail = FALSE; /* * Try to get it via a hairy and expensive scheme. * First we get the name of the executable. */ if (will_fail) break; if (!found_exe_name) { int ret_code = readlink("/proc/self/exe", exe_name, EXE_SZ); if (ret_code < 0 || ret_code >= EXE_SZ || exe_name[0] != '/') { /* Do not try again. */ will_fail = TRUE; break; } exe_name[ret_code] = '\0'; found_exe_name = TRUE; } /* * Then we use `popen()` to start `addr2line -e `. * There are faster ways to do this, but hopefully this is * not time critical. */ (void)snprintf(cmd_buf, sizeof(cmd_buf), "/usr/bin/addr2line -f -e %s 0x%lx", exe_name, (unsigned long)ADDR(info[i].ci_pc)); cmd_buf[sizeof(cmd_buf) - 1] = '\0'; old_preload = GETENV("LD_PRELOAD"); if (old_preload != NULL) { size_t old_len = strlen(old_preload); if (old_len >= PRELOAD_SZ) { will_fail = TRUE; break; } BCOPY(old_preload, preload_buf, old_len + 1); unsetenv("LD_PRELOAD"); } pipe = popen(cmd_buf, "r"); if (old_preload != NULL && setenv("LD_PRELOAD", preload_buf, 0 /* `overwrite` */) == -1) { WARN("Failed to reset LD_PRELOAD\n", 0); } if (NULL == pipe) { will_fail = TRUE; break; } result_len = fread(result_buf, 1, RESULT_SZ - 1, pipe); (void)pclose(pipe); if (0 == result_len) { will_fail = TRUE; break; } if (result_buf[result_len - 1] == '\n') --result_len; result_buf[result_len] = 0; if (result_buf[0] == '?' || (result_buf[result_len - 2] == ':' && result_buf[result_len - 1] == '0')) break; /* Get rid of embedded newline, if any. Test for "main". */ { char *nl = strchr(result_buf, '\n'); if (nl != NULL && ADDR_LT(nl, result_buf + result_len)) { *nl = ':'; } if (strncmp(result_buf, "main", nl != NULL ? (size_t)(ADDR(nl) /*< CPPCHECK */ - COVERT_DATAFLOW(ADDR(result_buf))) : result_len) == 0) { stop = TRUE; } } if (result_len < RESULT_SZ - 25) { /* Add address in the hex format. */ (void)snprintf(&result_buf[result_len], sizeof(result_buf) - result_len, " [0x%lx]", (unsigned long)ADDR(info[i].ci_pc)); result_buf[sizeof(result_buf) - 1] = '\0'; } # if defined(CPPCHECK) GC_noop1((unsigned char)name[0]); /* The value of name computed previously is discarded. */ # endif name = result_buf; } while (0); # endif /* LINUX */ GC_err_printf("\t\t%s\n", name); # if defined(GC_HAVE_BUILTIN_BACKTRACE) \ && !defined(GC_BACKTRACE_SYMBOLS_BROKEN) && defined(FUNCPTR_IS_DATAPTR) if (sym_name != NULL) { /* May call `GC_free()`, `GC_debug_free()`; that is OK. */ free(sym_name); } # endif } # if defined(LINUX) && !defined(SMALL_CONFIG) if (stop) break; # endif } # if defined(AO_HAVE_fetch_and_add1) && defined(AO_HAVE_fetch_and_sub1) (void)AO_fetch_and_sub1(&reentry_count); # else LOCK(); --reentry_count; UNLOCK(); # endif } #endif /* NEED_CALLINFO */ #if defined(LINUX) && defined(__ELF__) && !defined(SMALL_CONFIG) /* * Dump `/proc/self/maps` file to `GC_stderr`, to enable looking up names * for addresses in `FIND_LEAK` output. */ void GC_print_address_map(void) { const char *maps_ptr; GC_ASSERT(I_HOLD_LOCK()); maps_ptr = GC_get_maps(); GC_err_printf("---------- Begin address map ----------\n"); GC_err_puts(maps_ptr); GC_err_printf("---------- End address map ----------\n"); } #endif /* LINUX && ELF */