runtime: set m.procid always on Linux

For debuggers and other program inspectors.

Fixes #9914.

Change-Id: I670728cea28c045e6eaba1808c550ee2f34d16ff
Reviewed-on: https://go-review.googlesource.com/11341Reviewed-by: Austin Clements <austin@google.com>

src/runtime/os1_linux.go

@@ -197,6 +197,8 @@ func msigsave(mp *m) {
 	rtsigprocmask(_SIG_SETMASK, nil, smask, int32(unsafe.Sizeof(*smask)))
 }
 
+func gettid() uint32
+
 // Called to initialize a new m (including the bootstrap m).
 // Called on the new thread, can not allocate memory.
 func minit() {
@@ -204,6 +206,9 @@ func minit() {
 	_g_ := getg()
 	signalstack(&_g_.m.gsignal.stack)
 
+	// for debuggers, in case cgo created the thread
+	_g_.m.procid = uint64(gettid())
+
 	// restore signal mask from m.sigmask and unblock essential signals
 	nmask := *(*sigset)(unsafe.Pointer(&_g_.m.sigmask))
 	for i := range sigtable {

src/runtime/sys_linux_386.s

@@ -96,6 +96,12 @@ TEXT runtime·usleep(SB),NOSPLIT,$8
 	CALL	*runtime·_vdso(SB)
 	RET
 
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	MOVL	$224, AX	// syscall - gettid
+	CALL	*runtime·_vdso(SB)
+	MOVL	AX, ret+0(FP)
+	RET
+
 TEXT runtime·raise(SB),NOSPLIT,$12
 	MOVL	$224, AX	// syscall - gettid
 	CALL	*runtime·_vdso(SB)

src/runtime/sys_linux_amd64.s

@@ -94,6 +94,12 @@ TEXT runtime·usleep(SB),NOSPLIT,$16
 	SYSCALL
 	RET
 
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	MOVL	$186, AX	// syscall - gettid
+	SYSCALL
+	MOVL	AX, ret+0(FP)
+	RET
+
 TEXT runtime·raise(SB),NOSPLIT,$0
 	MOVL	$186, AX	// syscall - gettid
 	SYSCALL

src/runtime/sys_linux_arm.s

@@ -121,6 +121,12 @@ TEXT runtime·exit1(SB),NOSPLIT,$-4
 	MOVW	$1003, R1
 	MOVW	R0, (R1)	// fail hard
 
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	MOVW	$SYS_gettid, R7
+	SWI	$0
+	MOVW	R0, ret+0(FP)
+	RET
+
 TEXT	runtime·raise(SB),NOSPLIT,$-4
 	MOVW	$SYS_gettid, R7
 	SWI	$0

src/runtime/sys_linux_arm64.s

@@ -136,6 +136,12 @@ TEXT runtime·usleep(SB),NOSPLIT,$16-4
 	SVC
 	RET
 
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	MOVD	$SYS_gettid, R8
+	SVC
+	MOVW	R0, ret+0(FP)
+	RET
+
 TEXT runtime·raise(SB),NOSPLIT,$-8
 	MOVD	$SYS_gettid, R8
 	SVC

src/runtime/sys_linux_ppc64x.s

@@ -121,6 +121,11 @@ TEXT runtime·usleep(SB),NOSPLIT,$16-4
 	SYSCALL	$SYS_newselect
 	RET
 
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	SYSCALL	$SYS_gettid
+	MOVW	R3, ret+0(FP)
+	RET
+
 TEXT runtime·raise(SB),NOSPLIT,$-8
 	SYSCALL	$SYS_gettid
 	MOVW	R3, R3	// arg 1 tid