runtime: make go work on netbsd/amd64

R=golang-dev, rsc, devon.odell
CC=golang-dev
https://golang.org/cl/6222044

src/pkg/runtime/os_netbsd.h

@@ -16,9 +16,9 @@ void	runtime·setsig(int32, void(*)(int32, Siginfo*, void*, G*), bool);
 void	runtime·sighandler(int32 sig, Siginfo *info, void *context, G *gp);
 void	runtime·sigpanic(void);
 
+void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 void	runtime·sigaction(int32, struct sigaction*, struct sigaction*);
 void	runtime·sigaltstack(Sigaltstack*, Sigaltstack*);
-void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 void	runtime·sigprocmask(int32, Sigset*, Sigset*);
 int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 

src/pkg/runtime/signal_netbsd_amd64.c

@@ -7,6 +7,7 @@
 #include "signals_GOOS.h"
 #include "os_GOOS.h"
 
+extern void runtime·lwp_tramp(void);
 extern void runtime·sigtramp(void);
 
 typedef struct sigaction {
@@ -143,3 +144,14 @@ runtime·setsig(int32 i, void (*fn)(int32, Siginfo*, void*, G*), bool restart)
 	sa._sa_u._sa_sigaction = (void*)fn;
 	runtime·sigaction(i, &sa, nil);
 }
+
+void
+runtime·lwp_mcontext_init(McontextT *mc, void *stack, M *m, G *g, void (*fn)(void))
+{
+	// Machine dependent mcontext initialisation for LWP.
+	mc->__gregs[REG_RIP] = (uint64)runtime·lwp_tramp;
+	mc->__gregs[REG_RSP] = (uint64)stack;
+	mc->__gregs[REG_R8] = (uint64)m;
+	mc->__gregs[REG_R9] = (uint64)g;
+	mc->__gregs[REG_R12] = (uint64)fn;
+}

src/pkg/runtime/sys_netbsd_amd64.s

@@ -8,42 +8,25 @@
 
 #include "zasm_GOOS_GOARCH.h"
 
-// int64 rfork_thread(int32 flags, void *stack, M *m, G *g, void (*fn)(void));
-TEXT runtime·rfork_thread(SB),7,$0
-	MOVL	flags+8(SP), DI
-	MOVQ	stack+16(SP), SI
+// int64 lwp_create(void *context, uintptr flags, void *lwpid)
+TEXT runtime·lwp_create(SB),7,$0
 
-	// Copy m, g, fn off parent stack for use by child.
-	MOVQ	mm+24(SP), R8
-	MOVQ	gg+32(SP), R9
-	MOVQ	fn+40(SP), R12
-
-	MOVL	$251, AX		// sys_rfork
+	MOVQ	context+0(FP), DI
+	MOVQ	flags+8(FP), SI
+	MOVQ	lwpid+16(FP), DX
+	MOVL	$309, AX		// sys__lwp_create
 	SYSCALL
-
-	// Return if rfork syscall failed
-	JCC	3(PC)
+	JCC	2(PC)
 	NEGL	AX
 	RET
 
-	// In parent, return.
-	CMPL	AX, $0
-	JEQ	2(PC)
-	RET
-
-	// In child, on new stack.
-	MOVQ	SI, SP
-
-	// Initialize m->procid to thread ID
-	MOVL	$299, AX		// sys_getthrid
-	SYSCALL
-	MOVQ	AX, m_procid(R8)
-
+TEXT runtime·lwp_tramp(SB),7,$0
+	
 	// Set FS to point at m->tls.
 	LEAQ	m_tls(R8), DI
 	CALL	runtime·settls(SB)
 
-	// In child, set up new stack
+	// Set up new stack.
 	get_tls(CX)
 	MOVQ	R8, m(CX)
 	MOVQ	R9, g(CX)
@@ -52,8 +35,8 @@ TEXT runtime·rfork_thread(SB),7,$0
 	// Call fn
 	CALL	R12
 
-	// It shouldn't return.  If it does, exit
-	MOVL	$302, AX		// sys_threxit
+	// It shouldn't return.  If it does, exit.
+	MOVL	$310, AX		// sys__lwp_exit
 	SYSCALL
 	JMP	-3(PC)			// keep exiting
 
@@ -62,19 +45,19 @@ TEXT runtime·osyield(SB),7,$0
 	SYSCALL
 	RET
 
-TEXT runtime·thrsleep(SB),7,$0
-	MOVQ	8(SP), DI		// arg 1 - ident
-	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
+TEXT runtime·lwp_park(SB),7,$0
+	MOVQ	8(SP), DI		// arg 1 - abstime
+	MOVL	16(SP), SI		// arg 2 - unpark
+	MOVQ	24(SP), DX		// arg 3 - hint
+	MOVQ	32(SP), R10		// arg 4 - unparkhint
+	MOVL	$434, AX		// sys__lwp_park
 	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
+TEXT runtime·lwp_unpark(SB),7,$0
+	MOVQ	8(SP), DI		// arg 1 - lwp
+	MOVL	16(SP), SI		// arg 2 - hint
+	MOVL	$321, AX		// sys__lwp_unpark
 	SYSCALL
 	RET
 

src/pkg/runtime/thread_netbsd.c

@@ -11,7 +11,7 @@ enum
 	ESRCH = 3,
 	ENOTSUP = 91,
 
-	// From NetBSD's sys/time.h
+	// From NetBSD's <sys/time.h>
 	CLOCK_REALTIME = 0,
 	CLOCK_VIRTUAL = 1,
 	CLOCK_PROF = 2,
@@ -20,9 +20,14 @@ enum
 
 extern SigTab runtime·sigtab[];
 
-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·thrwakeup(void *ident, int32 n);
+static Sigset sigset_all = { ~(uint32)0, ~(uint32)0, ~(uint32)0, ~(uint32)0, };
+static Sigset sigset_none;
+
+extern void runtime·getcontext(UcontextT *context);
+extern int32 runtime·lwp_create(UcontextT *context, uintptr flags, void *lwpid);
+extern void runtime·lwp_mcontext_init(void *mc, void *stack, M *m, G *g, void (*fn)(void));
+extern int32 runtime·lwp_park(Timespec *abstime, int32 unpark, void *hint, void *unparkhint);
+extern int32 runtime·lwp_unpark(int32 lwp, void *hint);
 
 // From NetBSD's <sys/sysctl.h>
 #define	CTL_HW	6
@@ -68,13 +73,30 @@ runtime·semasleep(int64 ns)
 		if(m->waitsemacount == 0) {
 			// sleep until semaphore != 0 or timeout.
 			// thrsleep unlocks m->waitsemalock.
-			if(ns < 0)
-				runtime·thrsleep(&m->waitsemacount, 0, nil, &m->waitsemalock);
-			else {
+			if(ns < 0) {
+				// TODO(jsing) - potential deadlock!
+				//
+				// There is a potential deadlock here since we
+				// have to release the waitsemalock mutex
+				// before we call lwp_park() to suspend the
+				// thread. This allows another thread to
+				// release the lock and call lwp_unpark()
+				// before the thread is actually suspended.
+				// If this occurs the current thread will end
+				// up sleeping indefinitely. Unfortunately
+				// the NetBSD kernel does not appear to provide
+				// a mechanism for unlocking the userspace
+				// mutex once the thread is actually parked.
+				runtime·atomicstore(&m->waitsemalock, 0);
+				runtime·lwp_park(nil, 0, &m->waitsemacount, nil);
+			} else {
 				ns += runtime·nanotime();
 				ts.tv_sec = ns/1000000000LL;
 				ts.tv_nsec = ns%1000000000LL;
-				runtime·thrsleep(&m->waitsemacount, CLOCK_REALTIME, &ts, &m->waitsemalock);
+				// TODO(jsing) - potential deadlock!
+				// See above for details.
+				runtime·atomicstore(&m->waitsemalock, 0);
+				runtime·lwp_park(&ts, 0, &m->waitsemacount, nil);
 			}
 			// reacquire lock
 			while(runtime·xchg(&m->waitsemalock, 1))
@@ -112,28 +134,26 @@ runtime·semawakeup(M *mp)
 	while(runtime·xchg(&mp->waitsemalock, 1))
 		runtime·osyield();
 	mp->waitsemacount++;
-	ret = runtime·thrwakeup(&mp->waitsemacount, 1);
+	// TODO(jsing) - potential deadlock, see semasleep() for details.
+	// Confirm that LWP is parked before unparking...
+	ret = runtime·lwp_unpark(mp->procid, &mp->waitsemacount);
 	if(ret != 0 && ret != ESRCH)
 		runtime·printf("thrwakeup addr=%p sem=%d ret=%d\n", &mp->waitsemacount, mp->waitsemacount, ret);
 	// spin-mutex unlock
 	runtime·atomicstore(&mp->waitsemalock, 0);
 }
 
-// From NetBSD's sys/param.h
-#define	RFPROC		(1<<4)	/* change child (else changes curproc) */
-#define	RFMEM		(1<<5)	/* share `address space' */
-#define	RFNOWAIT	(1<<6)	/* parent need not wait() on child */
-#define	RFTHREAD	(1<<13)	/* create a thread, not a process */
+// From NetBSD's <sys/ucontext.h>
+#define _UC_SIGMASK	0x01
+#define _UC_CPU		0x04
 
 void
 runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
 {
-	int32 flags;
+	UcontextT uc;
 	int32 ret;
 
-	flags = RFPROC | RFTHREAD | RFMEM | RFNOWAIT;
-
-	if (0) {
+	if(0) {
 		runtime·printf(
 			"newosproc stk=%p m=%p g=%p fn=%p id=%d/%d ostk=%p\n",
 			stk, m, g, fn, m->id, m->tls[0], &m);
@@ -141,10 +161,18 @@ runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
 
 	m->tls[0] = m->id;	// so 386 asm can find it
 
-	if((ret = runtime·rfork_thread(flags, stk, m, g, fn)) < 0) {
+	runtime·getcontext(&uc);
+	
+	uc.uc_flags = _UC_SIGMASK | _UC_CPU;
+	uc.uc_link = nil;
+	uc.uc_sigmask = sigset_all;
+
+	runtime·lwp_mcontext_init(&uc.uc_mcontext, stk, m, g, fn);
+
+	ret = runtime·lwp_create(&uc, 0, &m->procid);
+
+	if(ret < 0) {
 		runtime·printf("runtime: failed to create new OS thread (have %d already; errno=%d)\n", runtime·mcount() - 1, -ret);
-		if (ret == -ENOTSUP)
-			runtime·printf("runtime: is kern.rthreads disabled?\n");
 		runtime·throw("runtime.newosproc");
 	}
 }
@@ -153,6 +181,9 @@ void
 runtime·osinit(void)
 {
 	runtime·ncpu = getncpu();
+
+	// Main thread is always LWP 1.
+	m->procid = 1;
 }
 
 void
@@ -168,6 +199,7 @@ runtime·minit(void)
 	// Initialize signal handling
 	m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack(m->gsignal->stackguard - StackGuard, 32*1024);
+	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
 }
 
 void