github.com/jwijenbergh/purego@v0.0.0-20240126093400-70ff3a61df13/internal/fakecgo/go_linux_amd64.go (about) 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 package fakecgo 6 7 import "unsafe" 8 9 //go:nosplit 10 func _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 40 var x_threadentry_trampoline byte 41 var threadentry_trampolineABI0 = &x_threadentry_trampoline 42 43 //go:nosplit 44 func 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 58 var setg_func uintptr 59 60 //go:nosplit 61 func 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 }