all: merge NaCl branch (part 1)

See golang.org/s/go13nacl for design overview.

This CL is the mostly mechanical changes from rsc's Go 1.2 based NaCl branch, specifically 39cb35750369 to 500771b477cf from https://code.google.com/r/rsc-go13nacl. This CL does not include working NaCl support, there are probably two or three more large merges to come.

CL 15750044 is not included as it involves more invasive changes to the linker which will need to be merged separately.

The exact change lists included are

15050047: syscall: support for Native Client
15360044: syscall: unzip implementation for Native Client
15370044: syscall: Native Client SRPC implementation
15400047: cmd/dist, cmd/go, go/build, test: support for Native Client
15410048: runtime: support for Native Client
15410049: syscall: file descriptor table for Native Client
15410050: syscall: in-memory file system for Native Client
15440048: all: update +build lines for Native Client port
15540045: cmd/6g, cmd/8g, cmd/gc: support for Native Client
15570045: os: support for Native Client
15680044: crypto/..., hash/crc32, reflect, sync/atomic: support for amd64p32
15690044: net: support for Native Client
15690048: runtime: support for fake time like on Go Playground
15690051: build: disable various tests on Native Client

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68150047

23 files changed, 856 insertions, 28 deletions

diff --git a/src/pkg/runtime/arch_386.h b/src/pkg/runtime/arch_386.h
index ebdb3ff4e2..5c0a54f8c0 100644
--- a/src/pkg/runtime/arch_386.h
+++ b/src/pkg/runtime/arch_386.h
@@ -7,5 +7,10 @@ enum {
 	BigEndian = 0,
 	CacheLineSize = 64,
 	RuntimeGogoBytes = 64,
+#ifdef GOOS_nacl
+	PhysPageSize = 65536,
+#else
+	PhysPageSize = 4096,
+#endif
 	PCQuantum = 1
 };
diff --git a/src/pkg/runtime/arch_amd64.h b/src/pkg/runtime/arch_amd64.h
index 171839481b..88b68cc6df 100644
--- a/src/pkg/runtime/arch_amd64.h
+++ b/src/pkg/runtime/arch_amd64.h
@@ -11,5 +11,10 @@ enum {
 #else
 	RuntimeGogoBytes = 64,
 #endif
+#ifdef GOOS_nacl
+	PhysPageSize = 65536,
+#else
+	PhysPageSize = 4096,
+#endif
 	PCQuantum = 1
 };
diff --git a/src/pkg/runtime/arch_amd64p32.h b/src/pkg/runtime/arch_amd64p32.h
new file mode 100644
index 0000000000..88b68cc6df
--- /dev/null
+++ b/src/pkg/runtime/arch_amd64p32.h
@@ -0,0 +1,20 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+enum {
+	thechar = '6',
+	BigEndian = 0,
+	CacheLineSize = 64,
+#ifdef GOOS_solaris
+	RuntimeGogoBytes = 80,
+#else
+	RuntimeGogoBytes = 64,
+#endif
+#ifdef GOOS_nacl
+	PhysPageSize = 65536,
+#else
+	PhysPageSize = 4096,
+#endif
+	PCQuantum = 1
+};
diff --git a/src/pkg/runtime/arch_arm.h b/src/pkg/runtime/arch_arm.h
index e5da01c603..b9711289f4 100644
--- a/src/pkg/runtime/arch_arm.h
+++ b/src/pkg/runtime/arch_arm.h
@@ -7,5 +7,6 @@ enum {
 	BigEndian = 0,
 	CacheLineSize = 32,
 	RuntimeGogoBytes = 80,
+	PhysPageSize = 4096,
 	PCQuantum = 4
 };
diff --git a/src/pkg/runtime/mem_linux.c b/src/pkg/runtime/mem_linux.c
index b0f2956335..2786ad70f6 100644
--- a/src/pkg/runtime/mem_linux.c
+++ b/src/pkg/runtime/mem_linux.c
@@ -11,6 +11,7 @@
 enum
 {
 	_PAGE_SIZE = 4096,
+	EACCES = 13,
 };
 
 static int32
diff --git a/src/pkg/runtime/mem_nacl.c b/src/pkg/runtime/mem_nacl.c
new file mode 100644
index 0000000000..993d194dd5
--- /dev/null
+++ b/src/pkg/runtime/mem_nacl.c
@@ -0,0 +1,109 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "malloc.h"
+
+enum
+{
+	Debug = 0,
+};
+
+void*
+runtime·SysAlloc(uintptr n, uint64 *stat)
+{
+	void *v;
+
+	v = runtime·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+	if(v < (void*)4096) {
+		if(Debug)
+			runtime·printf("SysAlloc(%p): %p\n", n, v);
+		return nil;
+	}
+	runtime·xadd64(stat, n);
+	if(Debug)
+		runtime·printf("SysAlloc(%p) = %p\n", n, v);
+	return v;
+}
+
+void
+runtime·SysUnused(void *v, uintptr n)
+{
+	if(Debug)
+		runtime·printf("SysUnused(%p, %p)\n", v, n);
+}
+
+void
+runtime·SysUsed(void *v, uintptr n)
+{
+	USED(v);
+	USED(n);
+}
+
+void
+runtime·SysFree(void *v, uintptr n, uint64 *stat)
+{
+	if(Debug)
+		runtime·printf("SysFree(%p, %p)\n", v, n);
+	runtime·xadd64(stat, -(uint64)n);
+	runtime·munmap(v, n);
+}
+
+void*
+runtime·SysReserve(void *v, uintptr n)
+{
+	void *p;
+
+	// On 64-bit, people with ulimit -v set complain if we reserve too
+	// much address space.  Instead, assume that the reservation is okay
+	// and check the assumption in SysMap.
+	if(NaCl || sizeof(void*) == 8)
+		return v;
+	
+	p = runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+	if(p < (void*)4096)
+		return nil;
+	return p;
+}
+
+void
+runtime·SysMap(void *v, uintptr n, uint64 *stat)
+{
+	void *p;
+	
+	runtime·xadd64(stat, n);
+
+	// On 64-bit, we don't actually have v reserved, so tread carefully.
+	if(sizeof(void*) == 8) {
+		p = runtime·mmap(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+		if(p == (void*)ENOMEM) {
+			runtime·printf("SysMap(%p, %p): %p\n", v, n, p);
+			runtime·throw("runtime: out of memory");
+		}
+		if(p != v) {
+			runtime·printf("SysMap(%p, %p): %p\n", v, n, p);
+			runtime·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
+			runtime·throw("runtime: address space conflict");
+		}
+		if(Debug)
+			runtime·printf("SysMap(%p, %p) = %p\n", v, n, p);
+		return;
+	}
+
+	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
+	if(p == (void*)ENOMEM) {
+		runtime·printf("SysMap(%p, %p): %p\n", v, n, p);
+		runtime·throw("runtime: out of memory");
+	}
+	if(p != v) {
+		runtime·printf("SysMap(%p, %p): %p\n", v, n, p);
+		runtime·printf("mmap MAP_FIXED %p returned %p\n", v, p);
+		runtime·throw("runtime: cannot map pages in arena address space");
+	}
+	if(Debug)
+		runtime·printf("SysMap(%p, %p) = %p\n", v, n, p);
+}
diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 95c3e83151..8d91a6db2e 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -2771,6 +2771,7 @@ runtime·MHeap_MapBits(MHeap *h)
 
 	n = (h->arena_used - h->arena_start) / wordsPerBitmapWord;
 	n = ROUND(n, bitmapChunk);
+	n = ROUND(n, PhysPageSize);
 	if(h->bitmap_mapped >= n)
 		return;
 
diff --git a/src/pkg/runtime/mheap.c b/src/pkg/runtime/mheap.c
index ba46b6404e..d89512d3f1 100644
--- a/src/pkg/runtime/mheap.c
+++ b/src/pkg/runtime/mheap.c
@@ -82,7 +82,7 @@ runtime·MHeap_MapSpans(MHeap *h)
 	n = (uintptr)h->arena_used;
 	n -= (uintptr)h->arena_start;
 	n = n / PageSize * sizeof(h->spans[0]);
-	n = ROUND(n, PageSize);
+	n = ROUND(n, PhysPageSize);
 	if(h->spans_mapped >= n)
 		return;
 	runtime·SysMap((byte*)h->spans + h->spans_mapped, n - h->spans_mapped, &mstats.other_sys);
diff --git a/src/pkg/runtime/mknacl.sh b/src/pkg/runtime/mknacl.sh
new file mode 100644
index 0000000000..47fb7bd88b
--- /dev/null
+++ b/src/pkg/runtime/mknacl.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+# Copyright 2013 The Go Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+cat /Users/rsc/pub/native_client/src/trusted/service_runtime/include/bits/nacl_syscalls.h |
+	awk '
+	BEGIN {
+		printf("// generated by mknacl.sh - do not edit\n")
+	}
+	NF==3 && $1=="#define" && $2~/^NACL_sys_/ {
+		name=$2
+		sub(/^NACL_sys_/, "SYS_", name)
+		printf("#define %s %s\n", name, $3)
+	}' >syscall_nacl.h
diff --git a/src/pkg/runtime/netpoll.goc b/src/pkg/runtime/netpoll.goc
index 9cc5eb5a36..77ddde9d60 100644
--- a/src/pkg/runtime/netpoll.goc
+++ b/src/pkg/runtime/netpoll.goc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
 
 package net
 
diff --git a/src/pkg/runtime/netpoll_nacl.c b/src/pkg/runtime/netpoll_nacl.c
new file mode 100644
index 0000000000..b75753a23b
--- /dev/null
+++ b/src/pkg/runtime/netpoll_nacl.c
@@ -0,0 +1,37 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+
+// Fake network poller for NaCl.
+// Should never be used, because NaCl network connections do not honor "SetNonblock".
+
+void
+runtime·netpollinit(void)
+{
+}
+
+int32
+runtime·netpollopen(uintptr fd, PollDesc *pd)
+{
+	USED(fd);
+	USED(pd);
+	return 0;
+}
+
+int32
+runtime·netpollclose(uintptr fd)
+{
+	USED(fd);
+	return 0;
+}
+
+G*
+runtime·netpoll(bool block)
+{
+	USED(block);
+	return nil;
+}
diff --git a/src/pkg/runtime/os_nacl.c b/src/pkg/runtime/os_nacl.c
new file mode 100644
index 0000000000..3c5e487ad1
--- /dev/null
+++ b/src/pkg/runtime/os_nacl.c
@@ -0,0 +1,275 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "arch_GOARCH.h"
+#include "../../cmd/ld/textflag.h"
+#include "stack.h"
+
+int8 *goos = "nacl";
+extern SigTab runtime·sigtab[];
+
+void runtime·sigtramp(void);
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
+void
+runtime·minit(void)
+{
+	int32 ret;
+
+	// Initialize signal handling
+	ret = runtime·nacl_exception_stack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
+	if(ret < 0)
+		runtime·printf("runtime: nacl_exception_stack: error %d\n", -ret);
+
+	ret = runtime·nacl_exception_handler(runtime·sigtramp, nil);
+	if(ret < 0)
+		runtime·printf("runtime: nacl_exception_handler: error %d\n", -ret);
+}
+
+// Called from dropm to undo the effect of an minit.
+void
+runtime·unminit(void)
+{
+}
+
+int8 runtime·sigtrampf[] = "runtime: signal at PC=%X AX=%X CX=%X DX=%X BX=%X DI=%X R15=%X *SP=%X\n";
+int8 runtime·sigtrampp[] = "runtime: sigtramp";
+
+extern byte runtime·tls0[];
+
+void
+runtime·osinit(void)
+{
+	runtime·ncpu = 1;
+	m->procid = 2;
+//runtime·nacl_exception_handler(runtime·sigtramp, nil);
+}
+
+void
+runtime·crash(void)
+{
+	*(int32*)0 = 0;
+}
+
+void
+runtime·get_random_data(byte **rnd, int32 *rnd_len)
+{
+	*rnd = nil;
+	*rnd_len = 0;
+}
+
+void
+runtime·goenvs(void)
+{
+	runtime·goenvs_unix();
+}
+
+void
+runtime·initsig(void)
+{
+}
+
+#pragma textflag NOSPLIT
+void
+runtime·usleep(uint32 us)
+{
+	Timespec ts;
+	
+	ts.tv_sec = us/1000000;
+	ts.tv_nsec = (us%1000000)*1000;
+	runtime·nacl_nanosleep(&ts, nil);
+}
+
+void runtime·mstart_nacl(void);
+
+void
+runtime·newosproc(M *mp, void *stk)
+{
+	int32 ret;
+	void **tls;
+
+	tls = (void**)mp->tls;
+	tls[0] = mp->g0;
+	tls[1] = mp;
+	ret = runtime·nacl_thread_create(runtime·mstart_nacl, stk, tls+2, 0);
+	if(ret < 0) {
+		runtime·printf("nacl_thread_create: error %d\n", -ret);
+		runtime·throw("newosproc");
+	}
+}
+
+uintptr
+runtime·semacreate(void)
+{
+	int32 mu, cond;
+	
+	mu = runtime·nacl_mutex_create(0);
+	if(mu < 0) {
+		runtime·printf("nacl_mutex_create: error %d\n", -mu);
+		runtime·throw("semacreate");
+	}
+	cond = runtime·nacl_cond_create(0);
+	if(cond < 0) {
+		runtime·printf("nacl_cond_create: error %d\n", -cond);
+		runtime·throw("semacreate");
+	}
+	m->waitsemalock = mu;
+	return cond; // assigned to m->waitsema
+}
+
+#pragma textflag NOSPLIT
+int32
+runtime·semasleep(int64 ns)
+{
+	int32 ret;
+	
+	ret = runtime·nacl_mutex_lock(m->waitsemalock);
+	if(ret < 0) {
+		//runtime·printf("nacl_mutex_lock: error %d\n", -ret);
+		runtime·throw("semasleep");
+	}
+	if(m->waitsemacount > 0) {
+		m->waitsemacount = 0;
+		runtime·nacl_mutex_unlock(m->waitsemalock);
+		return 0;
+	}
+
+	while(m->waitsemacount == 0) {
+		if(ns < 0) {
+			ret = runtime·nacl_cond_wait(m->waitsema, m->waitsemalock);
+			if(ret < 0) {
+				//runtime·printf("nacl_cond_wait: error %d\n", -ret);
+				runtime·throw("semasleep");
+			}
+		} else {
+			Timespec ts;
+			
+			ns += runtime·nanotime();
+			ts.tv_sec = runtime·timediv(ns, 1000000000, (int32*)&ts.tv_nsec);
+			ret = runtime·nacl_cond_timed_wait_abs(m->waitsema, m->waitsemalock, &ts);
+			if(ret == -ETIMEDOUT) {
+				runtime·nacl_mutex_unlock(m->waitsemalock);
+				return -1;
+			}
+			if(ret < 0) {
+				//runtime·printf("nacl_cond_timed_wait_abs: error %d\n", -ret);
+				runtime·throw("semasleep");
+			}
+		}
+	}
+			
+	m->waitsemacount = 0;
+	runtime·nacl_mutex_unlock(m->waitsemalock);
+	return 0;
+}
+
+void
+runtime·semawakeup(M *mp)
+{
+	int32 ret;
+	
+	ret = runtime·nacl_mutex_lock(mp->waitsemalock);
+	if(ret < 0) {
+		//runtime·printf("nacl_mutex_lock: error %d\n", -ret);
+		runtime·throw("semawakeup");
+	}
+	if(mp->waitsemacount != 0) {
+		//runtime·printf("semawakeup: double wakeup\n");
+		runtime·throw("semawakeup");
+	}
+	mp->waitsemacount = 1;
+	runtime·nacl_cond_signal(mp->waitsema);
+	runtime·nacl_mutex_unlock(mp->waitsemalock);
+}
+
+void
+os·sigpipe(void)
+{
+	runtime·throw("too many writes on closed pipe");
+}
+
+uintptr
+runtime·memlimit(void)
+{
+	runtime·printf("memlimit\n");
+	return 0;
+}
+
+#pragma dataflag NOPTR
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag NOSPLIT
+void
+runtime·badsignal2(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+	runtime·exit(2);
+}
+
+void	runtime·madvise(byte*, uintptr, int32) { }
+void runtime·munmap(byte*, uintptr) {}
+
+void
+runtime·resetcpuprofiler(int32 hz)
+{
+	USED(hz);
+}
+
+void
+runtime·sigdisable(uint32)
+{
+}
+
+void
+runtime·sigenable(uint32)
+{
+}
+
+void
+runtime·closeonexec(int32)
+{
+}
+
+void
+runtime·sigpanic(void)
+{
+	// Native Client only invokes the exception handler for memory faults.
+	g->sig = SIGSEGV;
+	if(g->sigpc == 0)
+		runtime·panicstring("call of nil func value");
+	runtime·panicstring("invalid memory address or nil pointer dereference");
+}
+
+uint32 runtime·writelock; // test-and-set spin lock for runtime.write
+
+/*
+An attempt at IRT. Doesn't work. See end of sys_nacl_amd64.s.
+
+void (*runtime·nacl_irt_query)(void);
+
+int8 runtime·nacl_irt_basic_v0_1_str[] = "nacl-irt-basic-0.1";
+void *runtime·nacl_irt_basic_v0_1[6]; // exit, gettod, clock, nanosleep, sched_yield, sysconf
+int32 runtime·nacl_irt_basic_v0_1_size = sizeof(runtime·nacl_irt_basic_v0_1);
+
+int8 runtime·nacl_irt_memory_v0_3_str[] = "nacl-irt-memory-0.3";
+void *runtime·nacl_irt_memory_v0_3[3]; // mmap, munmap, mprotect
+int32 runtime·nacl_irt_memory_v0_3_size = sizeof(runtime·nacl_irt_memory_v0_3);
+
+int8 runtime·nacl_irt_thread_v0_1_str[] = "nacl-irt-thread-0.1";
+void *runtime·nacl_irt_thread_v0_1[3]; // thread_create, thread_exit, thread_nice
+int32 runtime·nacl_irt_thread_v0_1_size = sizeof(runtime·nacl_irt_thread_v0_1);
+*/
\ No newline at end of file
diff --git a/src/pkg/runtime/os_nacl.h b/src/pkg/runtime/os_nacl.h
new file mode 100644
index 0000000000..7c9d9c242f
--- /dev/null
+++ b/src/pkg/runtime/os_nacl.h
@@ -0,0 +1,162 @@
+enum {
+	NSIG = 32,
+	SI_USER = 1,
+
+	// native_client/src/trusted/service_runtime/include/sys/errno.h
+	// The errors are mainly copied from Linux.
+	EPERM = 1,  /* Operation not permitted */
+	ENOENT = 2,  /* No such file or directory */
+	ESRCH = 3,  /* No such process */
+	EINTR = 4,  /* Interrupted system call */
+	EIO = 5,  /* I/O error */
+	ENXIO = 6,  /* No such device or address */
+	E2BIG = 7,  /* Argument list too long */
+	ENOEXEC = 8,  /* Exec format error */
+	EBADF = 9,  /* Bad file number */
+	ECHILD = 10,  /* No child processes */
+	EAGAIN = 11,  /* Try again */
+	ENOMEM = 12,  /* Out of memory */
+	EACCES = 13,  /* Permission denied */
+	EFAULT = 14,  /* Bad address */
+	EBUSY = 16,  /* Device or resource busy */
+	EEXIST = 17,  /* File exists */
+	EXDEV = 18,  /* Cross-device link */
+	ENODEV = 19,  /* No such device */
+	ENOTDIR = 20,  /* Not a directory */
+	EISDIR = 21,  /* Is a directory */
+	EINVAL = 22,  /* Invalid argument */
+	ENFILE = 23,  /* File table overflow */
+	EMFILE = 24,  /* Too many open files */
+	ENOTTY = 25,  /* Not a typewriter */
+	EFBIG = 27,  /* File too large */
+	ENOSPC = 28,  /* No space left on device */
+	ESPIPE = 29,  /* Illegal seek */
+	EROFS = 30,  /* Read-only file system */
+	EMLINK = 31,  /* Too many links */
+	EPIPE = 32,  /* Broken pipe */
+	ENAMETOOLONG = 36,  /* File name too long */
+	ENOSYS = 38,  /* Function not implemented */
+	EDQUOT = 122, /* Quota exceeded */
+	EDOM = 33,   /* Math arg out of domain of func */
+	ERANGE = 34, /* Math result not representable */
+	EDEADLK = 35,  /* Deadlock condition */
+	ENOLCK = 37, /* No record locks available */
+	ENOTEMPTY = 39,  /* Directory not empty */
+	ELOOP = 40,  /* Too many symbolic links */
+	ENOMSG = 42, /* No message of desired type */
+	EIDRM = 43,  /* Identifier removed */
+	ECHRNG = 44, /* Channel number out of range */
+	EL2NSYNC = 45, /* Level 2 not synchronized */
+	EL3HLT = 46, /* Level 3 halted */
+	EL3RST = 47, /* Level 3 reset */
+	ELNRNG = 48, /* Link number out of range */
+	EUNATCH = 49,  /* Protocol driver not attached */
+	ENOCSI = 50, /* No CSI structure available */
+	EL2HLT = 51, /* Level 2 halted */
+	EBADE = 52,  /* Invalid exchange */
+	EBADR = 53,  /* Invalid request descriptor */
+	EXFULL = 54, /* Exchange full */
+	ENOANO = 55, /* No anode */
+	EBADRQC = 56,  /* Invalid request code */
+	EBADSLT = 57,  /* Invalid slot */
+	EDEADLOCK = EDEADLK,  /* File locking deadlock error */
+	EBFONT = 59, /* Bad font file fmt */
+	ENOSTR = 60, /* Device not a stream */
+	ENODATA = 61,  /* No data (for no delay io) */
+	ETIME = 62,  /* Timer expired */
+	ENOSR = 63,  /* Out of streams resources */
+	ENONET = 64, /* Machine is not on the network */
+	ENOPKG = 65, /* Package not installed */
+	EREMOTE = 66,  /* The object is remote */
+	ENOLINK = 67,  /* The link has been severed */
+	EADV = 68,   /* Advertise error */
+	ESRMNT = 69, /* Srmount error */
+	ECOMM = 70,  /* Communication error on send */
+	EPROTO = 71, /* Protocol error */
+	EMULTIHOP = 72,  /* Multihop attempted */
+	EDOTDOT = 73,  /* Cross mount point (not really error) */
+	EBADMSG = 74,  /* Trying to read unreadable message */
+	EOVERFLOW = 75, /* Value too large for defined data type */
+	ENOTUNIQ = 76, /* Given log. name not unique */
+	EBADFD = 77, /* f.d. invalid for this operation */
+	EREMCHG = 78,  /* Remote address changed */
+	ELIBACC = 79,  /* Can't access a needed shared lib */
+	ELIBBAD = 80,  /* Accessing a corrupted shared lib */
+	ELIBSCN = 81,  /* .lib section in a.out corrupted */
+	ELIBMAX = 82,  /* Attempting to link in too many libs */
+	ELIBEXEC = 83, /* Attempting to exec a shared library */
+	EILSEQ = 84,
+	EUSERS = 87,
+	ENOTSOCK = 88,  /* Socket operation on non-socket */
+	EDESTADDRREQ = 89,  /* Destination address required */
+	EMSGSIZE = 90,    /* Message too long */
+	EPROTOTYPE = 91,  /* Protocol wrong type for socket */
+	ENOPROTOOPT = 92, /* Protocol not available */
+	EPROTONOSUPPORT = 93, /* Unknown protocol */
+	ESOCKTNOSUPPORT = 94, /* Socket type not supported */
+	EOPNOTSUPP = 95, /* Operation not supported on transport endpoint */
+	EPFNOSUPPORT = 96, /* Protocol family not supported */
+	EAFNOSUPPORT = 97, /* Address family not supported by protocol family */
+	EADDRINUSE = 98,    /* Address already in use */
+	EADDRNOTAVAIL = 99, /* Address not available */
+	ENETDOWN = 100,    /* Network interface is not configured */
+	ENETUNREACH = 101,   /* Network is unreachable */
+	ENETRESET = 102,
+	ECONNABORTED = 103,  /* Connection aborted */
+	ECONNRESET = 104,  /* Connection reset by peer */
+	ENOBUFS = 105, /* No buffer space available */
+	EISCONN = 106,   /* Socket is already connected */
+	ENOTCONN = 107,    /* Socket is not connected */
+	ESHUTDOWN = 108, /* Can't send after socket shutdown */
+	ETOOMANYREFS = 109,
+	ETIMEDOUT = 110,   /* Connection timed out */
+	ECONNREFUSED = 111,  /* Connection refused */
+	EHOSTDOWN = 112,   /* Host is down */
+	EHOSTUNREACH = 113,  /* Host is unreachable */
+	EALREADY = 114,    /* Socket already connected */
+	EINPROGRESS = 115,   /* Connection already in progress */
+	ESTALE = 116,
+	ENOTSUP = EOPNOTSUPP,   /* Not supported */
+	ENOMEDIUM = 123,   /* No medium (in tape drive) */
+	ECANCELED = 125, /* Operation canceled. */
+	ELBIN = 2048,  /* Inode is remote (not really error) */
+	EFTYPE = 2049,  /* Inappropriate file type or format */
+	ENMFILE = 2050,  /* No more files */
+	EPROCLIM = 2051,
+	ENOSHARE = 2052,  /* No such host or network path */
+	ECASECLASH = 2053,  /* Filename exists with different case */
+	EWOULDBLOCK = EAGAIN,      /* Operation would block */
+
+	// native_client/src/trusted/service_runtime/include/bits/mman.h.
+	// NOTE: DO NOT USE native_client/src/shared/imc/nacl_imc_c.h.
+	// Those MAP_*values are different from these.
+	PROT_NONE	= 0x0,
+	PROT_READ	= 0x1,
+	PROT_WRITE	= 0x2,
+	PROT_EXEC	= 0x4,
+
+	MAP_SHARED	= 0x1,
+	MAP_PRIVATE	= 0x2,
+	MAP_FIXED	= 0x10,
+	MAP_ANON	= 0x20,
+};
+typedef byte* kevent_udata;
+
+int32	runtime·nacl_exception_stack(byte*, int32);
+int32	runtime·nacl_exception_handler(void*, void*);
+int32	runtime·nacl_sem_create(int32);
+int32	runtime·nacl_sem_wait(int32);
+int32	runtime·nacl_sem_post(int32);
+int32	runtime·nacl_mutex_create(int32);
+int32	runtime·nacl_mutex_lock(int32);
+int32	runtime·nacl_mutex_trylock(int32);
+int32	runtime·nacl_mutex_unlock(int32);
+int32	runtime·nacl_cond_create(int32);
+int32	runtime·nacl_cond_wait(int32, int32);
+int32	runtime·nacl_cond_signal(int32);
+int32	runtime·nacl_cond_broadcast(int32);
+int32	runtime·nacl_cond_timed_wait_abs(int32, int32, Timespec*);
+int32	runtime·nacl_thread_create(void*, void*, void*, void*);
+int32	runtime·nacl_nanosleep(Timespec*, Timespec*);
+
+void	runtime·sigpanic(void);
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index c9887b6637..0069d5a774 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -21,11 +21,19 @@ typedef	uint64		uintptr;
 typedef	int64		intptr;
 typedef	int64		intgo; // Go's int
 typedef	uint64		uintgo; // Go's uint
+typedef	uint64		uintreg;
 #else
 typedef	uint32		uintptr;
 typedef	int32		intptr;
 typedef	int32		intgo; // Go's int
 typedef	uint32		uintgo; // Go's uint
+typedef	uint32		uintreg;
+#endif
+
+#ifdef _64BITREG
+//typedef	uint64		uintreg;
+#else
+//typedef	uint32		uintreg;
 #endif
 
 /*
@@ -209,8 +217,8 @@ struct	Gobuf
 	uintptr	sp;
 	uintptr	pc;
 	G*	g;
-	uintptr	ret;
 	void*	ctxt;
+	uintreg	ret;
 	uintptr	lr;
 };
 struct	GCStats
@@ -295,8 +303,8 @@ struct	M
 
 	// Fields not known to debuggers.
 	uint32	moreframesize;	// size arguments to morestack
-	uint32	moreargsize;
-	uintptr	cret;		// return value from C
+	uint32	moreargsize;	// known by amd64 asm to follow moreframesize
+	uintreg	cret;		// return value from C
 	uint64	procid;		// for debuggers, but offset not hard-coded
 	G*	gsignal;	// signal-handling G
 	uintptr	tls[4];		// thread-local storage (for x86 extern register)
@@ -479,6 +487,16 @@ struct	Itab
 	void	(*fun[])(void);
 };
 
+#ifdef GOOS_nacl
+enum {
+   NaCl = 1,
+};
+#else
+enum {
+   NaCl = 0,
+};
+#endif
+
 #ifdef GOOS_windows
 enum {
    Windows = 1
@@ -512,6 +530,8 @@ struct	Timers
 
 // Package time knows the layout of this structure.
 // If this struct changes, adjust ../time/sleep.go:/runtimeTimer.
+// For GOOS=nacl, package syscall knows the layout of this structure.
+// If this struct changes, adjust ../syscall/net_nacl.go:/runtimeTimer.
 struct	Timer
 {
 	int32	i;	// heap index
@@ -588,7 +608,7 @@ extern bool runtime·precisestack;
  * known to compiler
  */
 enum {
-	Structrnd = sizeof(uintptr)
+	Structrnd = sizeof(uintreg),
 };
 
 /*
@@ -762,6 +782,7 @@ void	runtime·dump(byte*, int32);
 int32	runtime·runetochar(byte*, int32);
 int32	runtime·charntorune(int32*, uint8*, int32);
 
+
 /*
  * This macro is used when writing C functions
  * called as if they were Go functions.
@@ -774,8 +795,6 @@ int32	runtime·charntorune(int32*, uint8*, int32);
  * first output value. Almost all code should write such
  * functions in .goc files, where goc2c (part of cmd/dist)
  * can arrange the correct alignment for the target system.
- * Goc2c also takes care of conveying to the garbage collector
- * which parts of the argument list are input vs outputs.
  *
  * Therefore, do NOT use this macro if at all possible.
  */ 
@@ -926,6 +945,7 @@ void	runtime·parsedebugvars(void);
 void	_rt0_go(void);
 void*	runtime·funcdata(Func*, int32);
 int32	runtime·setmaxthreads(int32);
+G*	runtime·timejump(void);
 
 #pragma	varargck	argpos	runtime·printf	1
 #pragma	varargck	type	"c"	int32
@@ -1017,13 +1037,6 @@ void	runtime·parfordo(ParFor *desc);
 void	runtime·parforiters(ParFor*, uintptr, uintptr*, uintptr*);
 
 /*
- * This is consistent across Linux and BSD.
- * If a new OS is added that is different, move this to
- * $GOOS/$GOARCH/defs.h.
- */
-#define EACCES		13
-
-/*
  * low level C-called
  */
 // for mmap, we only pass the lower 32 bits of file offset to the 
@@ -1057,6 +1070,7 @@ void	reflect·call(FuncVal*, byte*, uint32);
 void	runtime·panic(Eface);
 void	runtime·panicindex(void);
 void	runtime·panicslice(void);
+void	runtime·panicdivide(void);
 
 /*
  * runtime c-called (but written in Go)
diff --git a/src/pkg/runtime/signal_386.c b/src/pkg/runtime/signal_386.c
index 553ea87e49..9f3f52179c 100644
--- a/src/pkg/runtime/signal_386.c
+++ b/src/pkg/runtime/signal_386.c
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux netbsd openbsd
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd
 
 #include "runtime.h"
 #include "defs_GOOS_GOARCH.h"
diff --git a/src/pkg/runtime/signal_nacl_386.h b/src/pkg/runtime/signal_nacl_386.h
new file mode 100644
index 0000000000..c9481b5f4f
--- /dev/null
+++ b/src/pkg/runtime/signal_nacl_386.h
@@ -0,0 +1,23 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define SIG_REGS(ctxt) (((ExcContext*)(ctxt))->regs)
+
+#define SIG_EAX(info, ctxt) (SIG_REGS(ctxt).eax)
+#define SIG_EBX(info, ctxt) (SIG_REGS(ctxt).ebx)
+#define SIG_ECX(info, ctxt) (SIG_REGS(ctxt).ecx)
+#define SIG_EDX(info, ctxt) (SIG_REGS(ctxt).edx)
+#define SIG_EDI(info, ctxt) (SIG_REGS(ctxt).edi)
+#define SIG_ESI(info, ctxt) (SIG_REGS(ctxt).esi)
+#define SIG_EBP(info, ctxt) (SIG_REGS(ctxt).ebp)
+#define SIG_ESP(info, ctxt) (SIG_REGS(ctxt).esp)
+#define SIG_EIP(info, ctxt) (SIG_REGS(ctxt).eip)
+#define SIG_EFLAGS(info, ctxt) (SIG_REGS(ctxt).eflags)
+
+#define SIG_CS(info, ctxt) (~0)
+#define SIG_FS(info, ctxt) (~0)
+#define SIG_GS(info, ctxt) (~0)
+
+#define SIG_CODE0(info, ctxt) (~0)
+#define SIG_CODE1(info, ctxt) (0)
diff --git a/src/pkg/runtime/signal_nacl_amd64p32.h b/src/pkg/runtime/signal_nacl_amd64p32.h
new file mode 100644
index 0000000000..c58593a291
--- /dev/null
+++ b/src/pkg/runtime/signal_nacl_amd64p32.h
@@ -0,0 +1,31 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define SIG_REGS(ctxt) (((ExcContext*)(ctxt))->regs64)
+
+#define SIG_RAX(info, ctxt) (SIG_REGS(ctxt).rax)
+#define SIG_RBX(info, ctxt) (SIG_REGS(ctxt).rbx)
+#define SIG_RCX(info, ctxt) (SIG_REGS(ctxt).rcx)
+#define SIG_RDX(info, ctxt) (SIG_REGS(ctxt).rdx)
+#define SIG_RDI(info, ctxt) (SIG_REGS(ctxt).rdi)
+#define SIG_RSI(info, ctxt) (SIG_REGS(ctxt).rsi)
+#define SIG_RBP(info, ctxt) (SIG_REGS(ctxt).rbp)
+#define SIG_RSP(info, ctxt) (SIG_REGS(ctxt).rsp)
+#define SIG_R8(info, ctxt) (SIG_REGS(ctxt).r8)
+#define SIG_R9(info, ctxt) (SIG_REGS(ctxt).r9)
+#define SIG_R10(info, ctxt) (SIG_REGS(ctxt).r10)
+#define SIG_R11(info, ctxt) (SIG_REGS(ctxt).r11)
+#define SIG_R12(info, ctxt) (SIG_REGS(ctxt).r12)
+#define SIG_R13(info, ctxt) (SIG_REGS(ctxt).r13)
+#define SIG_R14(info, ctxt) (SIG_REGS(ctxt).r14)
+#define SIG_R15(info, ctxt) (SIG_REGS(ctxt).r15)
+#define SIG_RIP(info, ctxt) (SIG_REGS(ctxt).rip)
+#define SIG_RFLAGS(info, ctxt) (SIG_REGS(ctxt).rflags)
+
+#define SIG_CS(info, ctxt) (~0)
+#define SIG_FS(info, ctxt) (~0)
+#define SIG_GS(info, ctxt) (~0)
+
+#define SIG_CODE0(info, ctxt) (~0)
+#define SIG_CODE1(info, ctxt) (0)
diff --git a/src/pkg/runtime/signals_nacl.h b/src/pkg/runtime/signals_nacl.h
new file mode 100644
index 0000000000..229b585902
--- /dev/null
+++ b/src/pkg/runtime/signals_nacl.h
@@ -0,0 +1,50 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define N SigNotify
+#define K SigKill
+#define T SigThrow
+#define P SigPanic
+#define D SigDefault
+
+SigTab runtime·sigtab[] = {
+	/* 0 */	0, "SIGNONE: no trap",
+	/* 1 */	N+K, "SIGHUP: terminal line hangup",
+	/* 2 */	N+K, "SIGINT: interrupt",
+	/* 3 */	N+T, "SIGQUIT: quit",
+	/* 4 */	T, "SIGILL: illegal instruction",
+	/* 5 */	T, "SIGTRAP: trace trap",
+	/* 6 */	N+T, "SIGABRT: abort",
+	/* 7 */	T, "SIGEMT: emulate instruction executed",
+	/* 8 */	P, "SIGFPE: floating-point exception",
+	/* 9 */	0, "SIGKILL: kill",
+	/* 10 */	P, "SIGBUS: bus error",
+	/* 11 */	P, "SIGSEGV: segmentation violation",
+	/* 12 */	T, "SIGSYS: bad system call",
+	/* 13 */	N, "SIGPIPE: write to broken pipe",
+	/* 14 */	N, "SIGALRM: alarm clock",
+	/* 15 */	N+K, "SIGTERM: termination",
+	/* 16 */	N, "SIGURG: urgent condition on socket",
+	/* 17 */	0, "SIGSTOP: stop",
+	/* 18 */	N+D, "SIGTSTP: keyboard stop",
+	/* 19 */	0, "SIGCONT: continue after stop",
+	/* 20 */	N, "SIGCHLD: child status has changed",
+	/* 21 */	N+D, "SIGTTIN: background read from tty",
+	/* 22 */	N+D, "SIGTTOU: background write to tty",
+	/* 23 */	N, "SIGIO: i/o now possible",
+	/* 24 */	N, "SIGXCPU: cpu limit exceeded",
+	/* 25 */	N, "SIGXFSZ: file size limit exceeded",
+	/* 26 */	N, "SIGVTALRM: virtual alarm clock",
+	/* 27 */	N, "SIGPROF: profiling alarm clock",
+	/* 28 */	N, "SIGWINCH: window size change",
+	/* 29 */	N, "SIGINFO: status request from keyboard",
+	/* 30 */	N, "SIGUSR1: user-defined signal 1",
+	/* 31 */	N, "SIGUSR2: user-defined signal 2",
+};
+
+#undef N
+#undef K
+#undef T
+#undef P
+#undef D
diff --git a/src/pkg/runtime/sys_x86.c b/src/pkg/runtime/sys_x86.c
index f24337eac7..a450b3e584 100644
--- a/src/pkg/runtime/sys_x86.c
+++ b/src/pkg/runtime/sys_x86.c
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 386
+// +build amd64 amd64p32 386
 
 #include "runtime.h"
 
@@ -14,6 +14,8 @@ runtime·gostartcall(Gobuf *gobuf, void (*fn)(void), void *ctxt)
 	uintptr *sp;
 	
 	sp = (uintptr*)gobuf->sp;
+	if(sizeof(uintreg) > sizeof(uintptr))
+		*--sp = 0;
 	*--sp = (uintptr)gobuf->pc;
 	gobuf->sp = (uintptr)sp;
 	gobuf->pc = (uintptr)fn;
diff --git a/src/pkg/runtime/syscall_nacl.h b/src/pkg/runtime/syscall_nacl.h
new file mode 100644
index 0000000000..b33852ec8d
--- /dev/null
+++ b/src/pkg/runtime/syscall_nacl.h
@@ -0,0 +1,71 @@
+// generated by mknacl.sh - do not edit
+#define SYS_null 1
+#define SYS_nameservice 2
+#define SYS_dup 8
+#define SYS_dup2 9
+#define SYS_open 10
+#define SYS_close 11
+#define SYS_read 12
+#define SYS_write 13
+#define SYS_lseek 14
+#define SYS_ioctl 15
+#define SYS_stat 16
+#define SYS_fstat 17
+#define SYS_chmod 18
+#define SYS_brk 20
+#define SYS_mmap 21
+#define SYS_munmap 22
+#define SYS_getdents 23
+#define SYS_mprotect 24
+#define SYS_list_mappings 25
+#define SYS_exit 30
+#define SYS_getpid 31
+#define SYS_sched_yield 32
+#define SYS_sysconf 33
+#define SYS_gettimeofday 40
+#define SYS_clock 41
+#define SYS_nanosleep 42
+#define SYS_clock_getres 43
+#define SYS_clock_gettime 44
+#define SYS_mkdir 45
+#define SYS_rmdir 46
+#define SYS_chdir 47
+#define SYS_getcwd 48
+#define SYS_unlink 49
+#define SYS_imc_makeboundsock 60
+#define SYS_imc_accept 61
+#define SYS_imc_connect 62
+#define SYS_imc_sendmsg 63
+#define SYS_imc_recvmsg 64
+#define SYS_imc_mem_obj_create 65
+#define SYS_imc_socketpair 66
+#define SYS_mutex_create 70
+#define SYS_mutex_lock 71
+#define SYS_mutex_trylock 72
+#define SYS_mutex_unlock 73
+#define SYS_cond_create 74
+#define SYS_cond_wait 75
+#define SYS_cond_signal 76
+#define SYS_cond_broadcast 77
+#define SYS_cond_timed_wait_abs 79
+#define SYS_thread_create 80
+#define SYS_thread_exit 81
+#define SYS_tls_init 82
+#define SYS_thread_nice 83
+#define SYS_tls_get 84
+#define SYS_second_tls_set 85
+#define SYS_second_tls_get 86
+#define SYS_exception_handler 87
+#define SYS_exception_stack 88
+#define SYS_exception_clear_flag 89
+#define SYS_sem_create 100
+#define SYS_sem_wait 101
+#define SYS_sem_post 102
+#define SYS_sem_get_value 103
+#define SYS_dyncode_create 104
+#define SYS_dyncode_modify 105
+#define SYS_dyncode_delete 106
+#define SYS_test_infoleak 109
+#define SYS_test_crash 110
+#define SYS_test_syscall_1 111
+#define SYS_test_syscall_2 112
diff --git a/src/pkg/runtime/traceback_x86.c b/src/pkg/runtime/traceback_x86.c
index fa46d547a8..bd431be224 100644
--- a/src/pkg/runtime/traceback_x86.c
+++ b/src/pkg/runtime/traceback_x86.c
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 386
+// +build amd64 amd64p32 386
 
 #include "runtime.h"
 #include "arch_GOARCH.h"
@@ -52,7 +52,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 	// Start in the caller's frame.
 	if(frame.pc == 0) {
 		frame.pc = *(uintptr*)frame.sp;
-		frame.sp += sizeof(uintptr);
+		frame.sp += sizeof(uintreg);
 	}
 	
 	f = runtime·findfunc(frame.pc);
@@ -101,14 +101,14 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 		// Derive frame pointer and link register.
 		if(frame.fp == 0) {
 			frame.fp = frame.sp + runtime·funcspdelta(f, frame.pc);
-			frame.fp += sizeof(uintptr); // caller PC
+			frame.fp += sizeof(uintreg); // caller PC
 		}
 		if(runtime·topofstack(f)) {
 			frame.lr = 0;
 			flr = nil;
 		} else {
 			if(frame.lr == 0)
-				frame.lr = ((uintptr*)frame.fp)[-1];
+				frame.lr = ((uintreg*)frame.fp)[-1];
 			flr = runtime·findfunc(frame.lr);
 			if(flr == nil) {
 				runtime·printf("runtime: unexpected return pc for %s called from %p\n", runtime·funcname(f), frame.lr);
@@ -117,7 +117,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 			}
 		}
 		
-		frame.varp = (byte*)frame.fp - sizeof(uintptr);
+		frame.varp = (byte*)frame.fp - sizeof(uintreg);
 
 		// Derive size of arguments.
 		// Most functions have a fixed-size argument block,
diff --git a/src/pkg/runtime/vlrt_386.c b/src/pkg/runtime/vlrt_386.c
index 8d965c086e..ace1beb4cc 100644
--- a/src/pkg/runtime/vlrt_386.c
+++ b/src/pkg/runtime/vlrt_386.c
@@ -32,6 +32,8 @@
  * to generate the code directly now.  Find and remove.
  */
 
+extern void runtime·panicdivide(void);
+
 typedef	unsigned long	ulong;
 typedef	unsigned int	uint;
 typedef	unsigned short	ushort;
@@ -240,6 +242,8 @@ dodiv(Vlong num, Vlong den, Vlong *qp, Vlong *rp)
 		}
 	} else {
 		if(num.hi >= den.lo){
+			if(den.lo == 0)
+				runtime·panicdivide();
 			q.hi = n = num.hi/den.lo;
 			num.hi -= den.lo*n;
 		} else {
@@ -263,6 +267,8 @@ _divvu(Vlong *q, Vlong n, Vlong d)
 {
 
 	if(n.hi == 0 && d.hi == 0) {
+		if(d.lo == 0)
+			runtime·panicdivide();
 		q->hi = 0;
 		q->lo = n.lo / d.lo;
 		return;
@@ -281,6 +287,8 @@ _modvu(Vlong *r, Vlong n, Vlong d)
 {
 
 	if(n.hi == 0 && d.hi == 0) {
+		if(d.lo == 0)
+			runtime·panicdivide();
 		r->hi = 0;
 		r->lo = n.lo % d.lo;
 		return;
@@ -319,6 +327,8 @@ _divv(Vlong *q, Vlong n, Vlong d)
 			q->hi = 0;
 			return;
 		}
+		if(d.lo == 0)
+			runtime·panicdivide();
 		q->lo = (long)n.lo / (long)d.lo;
 		q->hi = ((long)q->lo) >> 31;
 		return;
@@ -353,6 +363,8 @@ _modv(Vlong *r, Vlong n, Vlong d)
 			r->hi = 0;
 			return;
 		}
+		if(d.lo == 0)
+			runtime·panicdivide();
 		r->lo = (long)n.lo % (long)d.lo;
 		r->hi = ((long)r->lo) >> 31;
 		return;
diff --git a/src/pkg/runtime/vlrt_arm.c b/src/pkg/runtime/vlrt_arm.c
index 219163c60f..9606e16076 100644
--- a/src/pkg/runtime/vlrt_arm.c
+++ b/src/pkg/runtime/vlrt_arm.c
@@ -36,12 +36,6 @@ typedef signed char     schar;
 
 #define SIGN(n) (1UL<<(n-1))
 
-void
-runtime·panicdivide(void)
-{
-	runtime·panicstring("integer divide by zero");
-}
-
 typedef struct  Vlong   Vlong;
 struct  Vlong
 {