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 //go:nosplit
63 func x_cgo_init(g *G, setg uintptr) {
64 var size size_t
65 var attr *pthread_attr_t
66 67 /* The memory sanitizer distributed with versions of clang
68 before 3.8 has a bug: if you call mmap before malloc, mmap
69 may return an address that is later overwritten by the msan
70 library. Avoid this problem by forcing a call to malloc
71 here, before we ever call malloc.
72 73 This is only required for the memory sanitizer, so it's
74 unfortunate that we always run it. It should be possible
75 to remove this when we no longer care about versions of
76 clang before 3.8. The test for this is
77 misc/cgo/testsanitizers.
78 79 GCC works hard to eliminate a seemingly unnecessary call to
80 malloc, so we actually use the memory we allocate. */
81 82 setg_func = setg
83 attr = (*pthread_attr_t)(malloc(unsafe.Sizeof(*attr)))
84 if attr == nil {
85 println("fakecgo: malloc failed")
86 abort()
87 }
88 pthread_attr_init(attr)
89 pthread_attr_getstacksize(attr, &size)
90 // runtime/cgo uses __builtin_frame_address(0) instead of `uintptr(unsafe.Pointer(&size))`
91 // but this should be OK since we are taking the address of the first variable in this function.
92 g.stacklo = uintptr(unsafe.Pointer(&size)) - uintptr(size) + 4096
93 pthread_attr_destroy(attr)
94 free(unsafe.Pointer(attr))
95 }
96