Imported Upstream version 1.3upstream/1.3

1 files changed, 23 insertions, 7 deletions

diff --git a/src/pkg/runtime/mem_linux.c b/src/pkg/runtime/mem_linux.c
index b0f295633..635594c36 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
@@ -19,15 +20,22 @@ addrspace_free(void *v, uintptr n)
 	int32 errval;
 	uintptr chunk;
 	uintptr off;
-	static byte vec[4096];
+	
+	// NOTE: vec must be just 1 byte long here.
+	// Mincore returns ENOMEM if any of the pages are unmapped,
+	// but we want to know that all of the pages are unmapped.
+	// To make these the same, we can only ask about one page
+	// at a time. See golang.org/issue/7476.
+	static byte vec[1];
 
 	for(off = 0; off < n; off += chunk) {
 		chunk = _PAGE_SIZE * sizeof vec;
 		if(chunk > (n - off))
 			chunk = n - off;
 		errval = runtime·mincore((int8*)v + off, chunk, vec);
-		// errval is 0 if success, or -(error_code) if error.
-		if (errval == 0 || errval != -ENOMEM)
+		// ENOMEM means unmapped, which is what we want.
+		// Anything else we assume means the pages are mapped.
+		if (errval != -ENOMEM)
 			return 0;
 	}
 	return 1;
@@ -91,8 +99,14 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 	runtime·munmap(v, n);
 }
 
+void
+runtime·SysFault(void *v, uintptr n)
+{
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
+}
+
 void*
-runtime·SysReserve(void *v, uintptr n)
+runtime·SysReserve(void *v, uintptr n, bool *reserved)
 {
 	void *p;
 
@@ -100,7 +114,7 @@ runtime·SysReserve(void *v, uintptr n)
 	// much address space.  Instead, assume that the reservation is okay
 	// if we can reserve at least 64K and check the assumption in SysMap.
 	// Only user-mode Linux (UML) rejects these requests.
-	if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
+	if(sizeof(void*) == 8 && n > 1LL<<32) {
 		p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 		if (p != v) {
 			if(p >= (void*)4096)
@@ -108,24 +122,26 @@ runtime·SysReserve(void *v, uintptr n)
 			return nil;
 		}
 		runtime·munmap(p, 64<<10);
+		*reserved = false;
 		return v;
 	}
 
 	p = runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
 	if((uintptr)p < 4096)
 		return nil;
+	*reserved = true;
 	return p;
 }
 
 void
-runtime·SysMap(void *v, uintptr n, uint64 *stat)
+runtime·SysMap(void *v, uintptr n, bool reserved, 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 && (uintptr)v >= 0xffffffffU) {
+	if(!reserved) {
 		p = mmap_fixed(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
 		if(p == (void*)ENOMEM)
 			runtime·throw("runtime: out of memory");