runtime: correct out of memory error

Fixes #1511.

R=golang-dev, iant2
CC=golang-dev
https://golang.org/cl/4433065

src/pkg/runtime/darwin/mem.c

@@ -36,6 +36,11 @@ runtime·SysReserve(void *v, uintptr n)
 	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 }
 
+enum
+{
+	ENOMEM = 12,
+};
+
 void
 runtime·SysMap(void *v, uintptr n)
 {
@@ -43,6 +48,8 @@ runtime·SysMap(void *v, uintptr n)
 	
 	mstats.sys += n;
 	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
+	if(p == (void*)-ENOMEM)
+		runtime·throw("runtime: out of memory");
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");
 }

src/pkg/runtime/freebsd/mem.c

@@ -42,6 +42,11 @@ runtime·SysReserve(void *v, uintptr n)
 	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 }
 
+enum
+{
+	ENOMEM = 12,
+};
+
 void
 runtime·SysMap(void *v, uintptr n)
 {
@@ -52,6 +57,8 @@ runtime·SysMap(void *v, uintptr 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|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
+		if(p == (void*)-ENOMEM)
+			runtime·throw("runtime: out of memory");
 		if(p != v) {
 			runtime·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
 			runtime·throw("runtime: address space conflict");
@@ -60,6 +67,8 @@ runtime·SysMap(void *v, uintptr n)
 	}
 
 	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
+	if(p == (void*)-ENOMEM)
+		runtime·throw("runtime: out of memory");
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");
 }

src/pkg/runtime/linux/mem.c

@@ -48,6 +48,11 @@ runtime·SysReserve(void *v, uintptr n)
 	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 }
 
+enum
+{
+	ENOMEM = 12,
+};
+
 void
 runtime·SysMap(void *v, uintptr n)
 {
@@ -66,6 +71,8 @@ runtime·SysMap(void *v, uintptr n)
 	}
 
 	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
+	if(p == (void*)-ENOMEM)
+		runtime·throw("runtime: out of memory");
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");
 }