runtime: use raise instead of pthread_self and pthread_kill

pthread_self and pthread_kill are not safe to call from a signal
handler. In particular, pthread_self fails in iOS when called from
a signal handler context.

Use raise instead; it is signal handler safe and simpler.

Change-Id: I0cbfe25151aed245f55d7b76719ce06dc78c6a75
Reviewed-on: https://go-review.googlesource.com/113877
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/runtime/os_darwin.go

@@ -539,12 +539,6 @@ func sigtramp(fn uintptr, infostyle, sig uint32, info *siginfo, ctx unsafe.Point
 //go:noescape
 func setitimer(mode int32, new, old *itimerval)
 
-//go:nosplit
-func raise(sig uint32) {
-	tid := pthread_self()
-	pthread_kill(tid, int(sig))
-}
-
 func raiseproc(sig uint32)
 
 //extern SigTabTT runtime·sigtab[];

src/runtime/sys_darwin.go

@@ -41,10 +41,10 @@ func pthread_create_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
-func pthread_kill(thread pthread, sig int) (errno int32) {
-	return asmcgocall(unsafe.Pointer(funcPC(pthread_kill_trampoline)), unsafe.Pointer(&thread))
+func raise(sig uint32) {
+	asmcgocall(unsafe.Pointer(funcPC(raise_trampoline)), unsafe.Pointer(&sig))
 }
-func pthread_kill_trampoline()
+func raise_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
@@ -158,8 +158,7 @@ func exitThread(wait *uint32) {
 //go:cgo_import_dynamic libc_pthread_attr_setdetachstate pthread_attr_setdetachstate "/usr/lib/libSystem.B.dylib"
 //go:cgo_import_dynamic libc_pthread_create pthread_create "/usr/lib/libSystem.B.dylib"
 //go:cgo_import_dynamic libc_exit exit "/usr/lib/libSystem.B.dylib"
-//go:cgo_import_dynamic libc_pthread_kill pthread_kill "/usr/lib/libSystem.B.dylib"
-//go:cgo_import_dynamic libc_pthread_self pthread_self "/usr/lib/libSystem.B.dylib"
+//go:cgo_import_dynamic libc_raise raise "/usr/lib/libSystem.B.dylib"
 
 //go:cgo_import_dynamic libc_open open "/usr/lib/libSystem.B.dylib"
 //go:cgo_import_dynamic libc_close close "/usr/lib/libSystem.B.dylib"

src/runtime/sys_darwin_386.s

@@ -619,27 +619,14 @@ TEXT runtime·pthread_create_trampoline(SB),NOSPLIT,$0
 	POPL	BP
 	RET
 
-TEXT runtime·pthread_self_trampoline(SB),NOSPLIT,$0
+TEXT runtime·raise_trampoline(SB),NOSPLIT,$0
 	PUSHL   BP
 	MOVL    SP, BP
 	SUBL	$8, SP
-	CALL    libc_pthread_self(SB)
 	MOVL	16(SP), CX
-	MOVL	AX, (CX)	// Save result.
-	MOVL    BP, SP
-	POPL    BP
-	RET
-
-TEXT runtime·pthread_kill_trampoline(SB),NOSPLIT,$0
-	PUSHL   BP
-	MOVL    SP, BP
-	SUBL	$8, SP
-	MOVL	16(SP), CX
-	MOVL    0(CX), AX	// arg 1 thread ID
+	MOVL    0(CX), AX	// arg 1 sig
 	MOVL	AX, 0(SP)
-	MOVL    4(CX), AX	// arg 2 sig
-	MOVL	AX, 4(SP)
-	CALL    libc_pthread_kill(SB)
+	CALL    libc_raise(SB)
 	MOVL    BP, SP
 	POPL    BP
 	RET

src/runtime/sys_darwin_amd64.s

@@ -590,20 +590,10 @@ TEXT runtime·pthread_create_trampoline(SB),NOSPLIT,$0
 	POPQ	BP
 	RET
 
-TEXT runtime·pthread_self_trampoline(SB),NOSPLIT,$0
+TEXT runtime·raise_trampoline(SB),NOSPLIT,$0
 	PUSHQ	BP
 	MOVQ	SP, BP
-	MOVQ	DI, BX		// Note: asmcgocall doesn't save anything in BX, so it is ok to clobber it here.
-	CALL	libc_pthread_self(SB)
-	MOVQ	AX, 0(BX)	// Save result.
-	POPQ	BP
-	RET
-
-TEXT runtime·pthread_kill_trampoline(SB),NOSPLIT,$0
-	PUSHQ	BP
-	MOVQ	SP, BP
-	MOVQ	8(DI), SI	// arg 2 signal
-	MOVQ	0(DI), DI	// arg 1 thread
-	CALL	libc_pthread_kill(SB)
+	MOVL	0(DI), DI	// arg 1 signal
+	CALL	libc_raise(SB)
 	POPQ	BP
 	RET