1 // Copyright 2011 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 //go:build !cgo
6 7 package fakecgo
8 9 import "unsafe"
10 11 //go:nosplit
12 func _cgo_sys_thread_start(ts *ThreadStart) {
13 var attr pthread_attr_t
14 var ign, oset sigset_t
15 var p pthread_t
16 var size size_t
17 var err int
18 19 //fprintf(stderr, "runtime/cgo: _cgo_sys_thread_start: fn=%p, g=%p\n", ts->fn, ts->g); // debug
20 sigfillset(&ign)
21 pthread_sigmask(SIG_SETMASK, &ign, &oset)
22 23 pthread_attr_init(&attr)
24 pthread_attr_getstacksize(&attr, &size)
25 // Leave stacklo=0 and set stackhi=size; mstart will do the rest.
26 ts.g.stackhi = uintptr(size)
27 28 err = _cgo_try_pthread_create(&p, &attr, unsafe.Pointer(threadentry_trampolineABI0), ts)
29 30 pthread_sigmask(SIG_SETMASK, &oset, nil)
31 32 if err != 0 {
33 print("fakecgo: pthread_create failed: ")
34 println(err)
35 abort()
36 }
37 }
38 39 // threadentry_trampolineABI0 maps the C ABI to Go ABI then calls the Go function
40 //
41 //go:linkname x_threadentry_trampoline threadentry_trampoline
42 var x_threadentry_trampoline byte
43 var threadentry_trampolineABI0 = &x_threadentry_trampoline
44 45 //go:nosplit
46 func threadentry(v unsafe.Pointer) unsafe.Pointer {
47 ts := *(*ThreadStart)(v)
48 free(v)
49 50 setg_trampoline(setg_func, uintptr(unsafe.Pointer(ts.g)))
51 52 // faking funcs in go is a bit a... involved - but the following works :)
53 fn := uintptr(unsafe.Pointer(&ts.fn))
54 (*(*func())(unsafe.Pointer(&fn)))()
55 56 return nil
57 }
58 59 // here we will store a pointer to the provided setg func
60 var setg_func uintptr
61 62 // x_cgo_init(G *g, void (*setg)(void*)) (runtime/cgo/gcc_linux_amd64.c)
63 // This get's called during startup, adjusts stacklo, and provides a pointer to setg_gcc for us
64 // Additionally, if we set _cgo_init to non-null, go won't do it's own TLS setup
65 // This function can't be go:systemstack since go is not in a state where the systemcheck would work.
66 //
67 //go:nosplit
68 func x_cgo_init(g *G, setg uintptr) {
69 var size size_t
70 var attr *pthread_attr_t
71 72 /* The memory sanitizer distributed with versions of clang
73 before 3.8 has a bug: if you call mmap before malloc, mmap
74 may return an address that is later overwritten by the msan
75 library. Avoid this problem by forcing a call to malloc
76 here, before we ever call malloc.
77 78 This is only required for the memory sanitizer, so it's
79 unfortunate that we always run it. It should be possible
80 to remove this when we no longer care about versions of
81 clang before 3.8. The test for this is
82 misc/cgo/testsanitizers.
83 84 GCC works hard to eliminate a seemingly unnecessary call to
85 malloc, so we actually use the memory we allocate. */
86 87 setg_func = setg
88 attr = (*pthread_attr_t)(malloc(unsafe.Sizeof(*attr)))
89 if attr == nil {
90 println("fakecgo: malloc failed")
91 abort()
92 }
93 pthread_attr_init(attr)
94 pthread_attr_getstacksize(attr, &size)
95 g.stacklo = uintptr(unsafe.Pointer(&size)) - uintptr(size) + 4096
96 pthread_attr_destroy(attr)
97 free(unsafe.Pointer(attr))
98 }
99