go_linux_arm64.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// x_cgo_init(G *g, void (*setg)(void*)) (runtime/cgo/gcc_linux_amd64.c)
61// This get's called during startup, adjusts stacklo, and provides a pointer to setg_gcc for us
62// Additionally, if we set _cgo_init to non-null, go won't do it's own TLS setup
63// This function can't be go:systemstack since go is not in a state where the systemcheck would work.
64//
65//go:nosplit
66func x_cgo_init(g *G, setg uintptr) {
67	var size size_t
68	var attr *pthread_attr_t
69
70	/* The memory sanitizer distributed with versions of clang
71	   before 3.8 has a bug: if you call mmap before malloc, mmap
72	   may return an address that is later overwritten by the msan
73	   library.  Avoid this problem by forcing a call to malloc
74	   here, before we ever call malloc.
75
76	   This is only required for the memory sanitizer, so it's
77	   unfortunate that we always run it.  It should be possible
78	   to remove this when we no longer care about versions of
79	   clang before 3.8.  The test for this is
80	   misc/cgo/testsanitizers.
81
82	   GCC works hard to eliminate a seemingly unnecessary call to
83	   malloc, so we actually use the memory we allocate.  */
84
85	setg_func = setg
86	attr = (*pthread_attr_t)(malloc(unsafe.Sizeof(*attr)))
87	if attr == nil {
88		println("fakecgo: malloc failed")
89		abort()
90	}
91	pthread_attr_init(attr)
92	pthread_attr_getstacksize(attr, &size)
93	g.stacklo = uintptr(unsafe.Pointer(&size)) - uintptr(size) + 4096
94	pthread_attr_destroy(attr)
95	free(unsafe.Pointer(attr))
96}

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