go_linux_amd64.go Raw History Folder

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
5package fakecgo
6
7import "unsafe"
8
9//go:nosplit
10func _cgo_sys_thread_start(ts *ThreadStart) {
11	var attr pthread_attr_t
12	var ign, oset sigset_t
13	var p pthread_t
14	var size size_t
15	var err int
16
17	//fprintf(stderr, "runtime/cgo: _cgo_sys_thread_start: fn=%p, g=%p\n", ts->fn, ts->g); // debug
18	sigfillset(&ign)
19	pthread_sigmask(SIG_SETMASK, &ign, &oset)
20
21	pthread_attr_init(&attr)
22	pthread_attr_getstacksize(&attr, &size)
23	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
24	ts.g.stackhi = uintptr(size)
25
26	err = _cgo_try_pthread_create(&p, &attr, unsafe.Pointer(threadentry_trampolineABI0), ts)
27
28	pthread_sigmask(SIG_SETMASK, &oset, nil)
29
30	if err != 0 {
31		print("fakecgo: pthread_create failed: ")
32		println(err)
33		abort()
34	}
35}
36
37// threadentry_trampolineABI0 maps the C ABI to Go ABI then calls the Go function
38//
39//go:linkname x_threadentry_trampoline threadentry_trampoline
40var x_threadentry_trampoline byte
41var threadentry_trampolineABI0 = &x_threadentry_trampoline
42
43//go:nosplit
44func threadentry(v unsafe.Pointer) unsafe.Pointer {
45	ts := *(*ThreadStart)(v)
46	free(v)
47
48	setg_trampoline(setg_func, uintptr(unsafe.Pointer(ts.g)))
49
50	// faking funcs in go is a bit a... involved - but the following works :)
51	fn := uintptr(unsafe.Pointer(&ts.fn))
52	(*(*func())(unsafe.Pointer(&fn)))()
53
54	return nil
55}
56
57// here we will store a pointer to the provided setg func
58var setg_func uintptr
59
60//go:nosplit
61func x_cgo_init(g *G, setg uintptr) {
62	var size size_t
63	var attr *pthread_attr_t
64
65	/* The memory sanitizer distributed with versions of clang
66	   before 3.8 has a bug: if you call mmap before malloc, mmap
67	   may return an address that is later overwritten by the msan
68	   library.  Avoid this problem by forcing a call to malloc
69	   here, before we ever call malloc.
70
71	   This is only required for the memory sanitizer, so it's
72	   unfortunate that we always run it.  It should be possible
73	   to remove this when we no longer care about versions of
74	   clang before 3.8.  The test for this is
75	   misc/cgo/testsanitizers.
76
77	   GCC works hard to eliminate a seemingly unnecessary call to
78	   malloc, so we actually use the memory we allocate.  */
79
80	setg_func = setg
81	attr = (*pthread_attr_t)(malloc(unsafe.Sizeof(*attr)))
82	if attr == nil {
83		println("fakecgo: malloc failed")
84		abort()
85	}
86	pthread_attr_init(attr)
87	pthread_attr_getstacksize(attr, &size)
88	// runtime/cgo uses __builtin_frame_address(0) instead of `uintptr(unsafe.Pointer(&size))`
89	// but this should be OK since we are taking the address of the first variable in this function.
90	g.stacklo = uintptr(unsafe.Pointer(&size)) - uintptr(size) + 4096
91	pthread_attr_destroy(attr)
92	free(unsafe.Pointer(attr))
93}

go_linux_amd64.go RawHistoryFolder

go_linux_amd64.go Raw History Folder