runtime: M-targeted signals for Linux

We'll add a test once all of the POSIX platforms are done.

For golang#10958, golang#24543.

Change-Id: If7e3f14e8391791364877629bf415d9f8e788b0a
Reviewed-on: https://go-review.googlesource.com/c/go/+/201401
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Author: aclements

src/runtime/os_linux.go

@@ -332,7 +332,9 @@ func gettid() uint32
 func minit() {
 	minitSignals()
 
-	// for debuggers, in case cgo created the thread
+	// Cgo-created threads and the bootstrap m are missing a
+	// procid. We need this for asynchronous preemption and its
+	// useful in debuggers.
 	getg().m.procid = uint64(gettid())
 }
 
@@ -454,3 +456,11 @@ func sysSigaction(sig uint32, new, old *sigactiont) {
 // rt_sigaction is implemented in assembly.
 //go:noescape
 func rt_sigaction(sig uintptr, new, old *sigactiont, size uintptr) int32
+
+func getpid() int
+func tgkill(tgid, tid, sig int)
+
+// signalM sends a signal to mp.
+func signalM(mp *m, sig int) {
+	tgkill(getpid(), int(mp.procid), sig)
+}

src/runtime/sys_linux_386.s

@@ -188,6 +188,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT,$12
 	INVOKE_SYSCALL
 	RET
 
+TEXT ·getpid(SB),NOSPLIT,$0-4
+	MOVL	$SYS_getpid, AX
+	INVOKE_SYSCALL
+	MOVL	AX, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0
+	MOVL	$SYS_tgkill, AX
+	MOVL	tgid+0(FP), BX
+	MOVL	tid+4(FP), CX
+	MOVL	sig+8(FP), DX
+	INVOKE_SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT,$0-12
 	MOVL	$SYS_setittimer, AX
 	MOVL	mode+0(FP), BX

src/runtime/sys_linux_amd64.s

@@ -171,6 +171,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT,$0
 	SYSCALL
 	RET
 
+TEXT ·getpid(SB),NOSPLIT,$0-8
+	MOVL	$SYS_getpid, AX
+	SYSCALL
+	MOVQ	AX, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0
+	MOVQ	tgid+0(FP), DI
+	MOVQ	tid+8(FP), SI
+	MOVQ	sig+16(FP), DX
+	MOVL	$SYS_tgkill, AX
+	SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT,$0-24
 	MOVL	mode+0(FP), DI
 	MOVQ	new+8(FP), SI

src/runtime/sys_linux_arm.s

@@ -172,6 +172,20 @@ TEXT	runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
 	SWI	$0
 	RET
 
+TEXT ·getpid(SB),NOSPLIT,$0-4
+	MOVW	$SYS_getpid, R7
+	SWI	$0
+	MOVW	R0, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0-12
+	MOVW	tgid+0(FP), R0
+	MOVW	tid+4(FP), R1
+	MOVW	sig+8(FP), R2
+	MOVW	$SYS_tgkill, R7
+	SWI	$0
+	RET
+
 TEXT runtime·mmap(SB),NOSPLIT,$0
 	MOVW	addr+0(FP), R0
 	MOVW	n+4(FP), R1

src/runtime/sys_linux_arm64.s

@@ -175,6 +175,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
 	SVC
 	RET
 
+TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
+	MOVD	$SYS_getpid, R8
+	SVC
+	MOVD	R0, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0-24
+	MOVD	tgid+0(FP), R0
+	MOVD	tid+8(FP), R1
+	MOVD	sig+16(FP), R2
+	MOVD	$SYS_tgkill, R8
+	SVC
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
 	MOVW	mode+0(FP), R0
 	MOVD	new+8(FP), R1

src/runtime/sys_linux_mips64x.s

@@ -177,6 +177,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
 	SYSCALL
 	RET
 
+TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
+	MOVV	$SYS_getpid, R2
+	SYSCALL
+	MOVV	R2, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT|NOFRAME,$0-24
+	MOVV	tgid+0(FP), R4
+	MOVV	tid+8(FP), R5
+	MOVV	sig+16(FP), R6
+	MOVV	$SYS_tgkill, R2
+	SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
 	MOVW	mode+0(FP), R4
 	MOVV	new+8(FP), R5

src/runtime/sys_linux_mipsx.s

@@ -183,6 +183,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT,$0
 	SYSCALL
 	RET
 
+TEXT ·getpid(SB),NOSPLIT,$0-4
+	MOVW	$SYS_getpid, R2
+	SYSCALL
+	MOVW	R2, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0-12
+	MOVW	tgid+0(FP), R4
+	MOVW	tid+4(FP), R5
+	MOVW	sig+8(FP), R6
+	MOVW	$SYS_tgkill, R2
+	SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT,$0-12
 	MOVW	mode+0(FP), R4
 	MOVW	new+4(FP), R5

src/runtime/sys_linux_ppc64x.s

@@ -156,6 +156,18 @@ TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
 	SYSCALL	$SYS_kill
 	RET
 
+TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
+	SYSCALL $SYS_getpid
+	MOVD	R3, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT|NOFRAME,$0-24
+	MOVD	tgid+0(FP), R3
+	MOVD	tid+8(FP), R4
+	MOVD	sig+16(FP), R5
+	SYSCALL $SYS_tgkill
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
 	MOVW	mode+0(FP), R3
 	MOVD	new+8(FP), R4

src/runtime/sys_linux_s390x.s

@@ -163,6 +163,20 @@ TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
 	SYSCALL
 	RET
 
+TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
+	MOVW	$SYS_getpid, R1
+	SYSCALL
+	MOVD	R2, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT|NOFRAME,$0-24
+	MOVD	tgid+0(FP), R2
+	MOVD	tid+8(FP), R3
+	MOVD	sig+16(FP), R4
+	MOVW	$SYS_tgkill, R1
+	SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
 	MOVW	mode+0(FP), R2
 	MOVD	new+8(FP), R3