github.com/comwrg/go/src@v0.0.0-20220319063731-c238d0440370/runtime/sys_darwin_arm64.go (about) 1 // Copyright 2020 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 runtime 6 7 import ( 8 "runtime/internal/sys" 9 "unsafe" 10 ) 11 12 // libc function wrappers. Must run on system stack. 13 14 //go:nosplit 15 //go:cgo_unsafe_args 16 func g0_pthread_key_create(k *pthreadkey, destructor uintptr) int32 { 17 ret := asmcgocall(unsafe.Pointer(funcPC(pthread_key_create_trampoline)), unsafe.Pointer(&k)) 18 KeepAlive(k) 19 return ret 20 } 21 func pthread_key_create_trampoline() 22 23 //go:nosplit 24 //go:cgo_unsafe_args 25 func g0_pthread_setspecific(k pthreadkey, value uintptr) int32 { 26 return asmcgocall(unsafe.Pointer(funcPC(pthread_setspecific_trampoline)), unsafe.Pointer(&k)) 27 } 28 func pthread_setspecific_trampoline() 29 30 //go:cgo_import_dynamic libc_pthread_key_create pthread_key_create "/usr/lib/libSystem.B.dylib" 31 //go:cgo_import_dynamic libc_pthread_setspecific pthread_setspecific "/usr/lib/libSystem.B.dylib" 32 33 // tlsinit allocates a thread-local storage slot for g. 34 // 35 // It finds the first available slot using pthread_key_create and uses 36 // it as the offset value for runtime.tlsg. 37 // 38 // This runs at startup on g0 stack, but before g is set, so it must 39 // not split stack (transitively). g is expected to be nil, so things 40 // (e.g. asmcgocall) will skip saving or reading g. 41 // 42 //go:nosplit 43 func tlsinit(tlsg *uintptr, tlsbase *[_PTHREAD_KEYS_MAX]uintptr) { 44 var k pthreadkey 45 err := g0_pthread_key_create(&k, 0) 46 if err != 0 { 47 abort() 48 } 49 50 const magic = 0xc476c475c47957 51 err = g0_pthread_setspecific(k, magic) 52 if err != 0 { 53 abort() 54 } 55 56 for i, x := range tlsbase { 57 if x == magic { 58 *tlsg = uintptr(i * sys.PtrSize) 59 g0_pthread_setspecific(k, 0) 60 return 61 } 62 } 63 abort() 64 }