runtime: update openbsd thread related syscalls to match kernel

Update the threxit and thrsleep syscalls to match the ABI of the
OpenBSD 5.1 kernel. These changes are backwards compatible with
older kernels.

Fixes #3311.

R=golang-dev, rsc, devon.odell
CC=golang-dev
https://golang.org/cl/5777079

src/pkg/runtime/sys_openbsd_386.s

@@ -15,8 +15,10 @@ TEXT runtime·exit(SB),7,$-4
 	MOVL	$0xf1, 0xf1		// crash
 	RET
 
-TEXT runtime·exit1(SB),7,$-4
-	MOVL	$302, AX		// sys_threxit
+TEXT runtime·exit1(SB),7,$8
+	MOVL	$0, 0(SP)
+	MOVL	$0, 4(SP)		// arg 1 - notdead
+	MOVL	$302, AX		// sys___threxit
 	INT	$0x80
 	JAE	2(PC)
 	MOVL	$0xf1, 0xf1		// crash
@@ -303,12 +305,12 @@ TEXT runtime·osyield(SB),7,$-4
 	RET
 
 TEXT runtime·thrsleep(SB),7,$-4
-	MOVL	$300, AX		// sys_thrsleep
+	MOVL	$300, AX		// sys___thrsleep
 	INT	$0x80
 	RET
 
 TEXT runtime·thrwakeup(SB),7,$-4
-	MOVL	$301, AX		// sys_thrwakeup
+	MOVL	$301, AX		// sys___thrwakeup
 	INT	$0x80
 	RET
 

src/pkg/runtime/sys_openbsd_amd64.s

@@ -53,7 +53,8 @@ TEXT runtime·rfork_thread(SB),7,$0
 	CALL	R12
 
 	// It shouldn't return.  If it does, exit
-	MOVL	$302, AX		// sys_threxit
+	MOVQ	$0, DI			// arg 1 - notdead
+	MOVL	$302, AX		// sys___threxit
 	SYSCALL
 	JMP	-3(PC)			// keep exiting
 
@@ -67,14 +68,15 @@ TEXT runtime·thrsleep(SB),7,$0
 	MOVL	16(SP), SI		// arg 2 - clock_id
 	MOVQ	24(SP), DX		// arg 3 - tp
 	MOVQ	32(SP), R10		// arg 4 - lock
-	MOVL	$300, AX		// sys_thrsleep
+	MOVQ	40(SP), R8		// arg 5 - abort
+	MOVL	$300, AX		// sys___thrsleep
 	SYSCALL
 	RET
 
 TEXT runtime·thrwakeup(SB),7,$0
 	MOVQ	8(SP), DI		// arg 1 - ident
 	MOVL	16(SP), SI		// arg 2 - n
-	MOVL	$301, AX		// sys_thrwakeup
+	MOVL	$301, AX		// sys___thrwakeup
 	SYSCALL
 	RET
 
@@ -87,7 +89,8 @@ TEXT runtime·exit(SB),7,$-8
 	RET
 
 TEXT runtime·exit1(SB),7,$-8
-	MOVL	$302, AX		// sys_threxit
+	MOVQ	$0, DI			// arg 1 - notdead
+	MOVL	$302, AX		// sys___threxit
 	SYSCALL
 	MOVL	$0xf1, 0xf1		// crash
 	RET

src/pkg/runtime/thread_openbsd.c

@@ -24,7 +24,7 @@ static Sigset sigset_all = ~(Sigset)0;
 static Sigset sigset_none;
 
 extern int64 runtime·rfork_thread(int32 flags, void *stack, M *m, G *g, void (*fn)(void));
-extern int32 runtime·thrsleep(void *ident, int32 clock_id, void *tsp, void *lock);
+extern int32 runtime·thrsleep(void *ident, int32 clock_id, void *tsp, void *lock, const int32 *abort);
 extern int32 runtime·thrwakeup(void *ident, int32 n);
 
 // From OpenBSD's <sys/sysctl.h>
@@ -72,12 +72,12 @@ runtime·semasleep(int64 ns)
 			// sleep until semaphore != 0 or timeout.
 			// thrsleep unlocks m->waitsemalock.
 			if(ns < 0)
-				runtime·thrsleep(&m->waitsemacount, 0, nil, &m->waitsemalock);
+				runtime·thrsleep(&m->waitsemacount, 0, nil, &m->waitsemalock, nil);
 			else {
 				ns += runtime·nanotime();
 				ts.tv_sec = ns/1000000000LL;
 				ts.tv_nsec = ns%1000000000LL;
-				runtime·thrsleep(&m->waitsemacount, CLOCK_REALTIME, &ts, &m->waitsemalock);
+				runtime·thrsleep(&m->waitsemacount, CLOCK_REALTIME, &ts, &m->waitsemalock, nil);
 			}
 			// reacquire lock
 			while(runtime·xchg(&m->waitsemalock, 1))