Imported Upstream version 58upstream/58

1 files changed, 39 insertions, 7 deletions

diff --git a/src/pkg/runtime/linux/mem.c b/src/pkg/runtime/linux/mem.c
index ce1a8aa70..38ca7e4a0 100644
--- a/src/pkg/runtime/linux/mem.c
+++ b/src/pkg/runtime/linux/mem.c
@@ -3,6 +3,30 @@
 #include "os.h"
 #include "malloc.h"
 
+enum
+{
+	ENOMEM = 12,
+};
+
+static int32
+addrspace_free(void *v, uintptr n)
+{
+	uintptr page_size = 4096;
+	uintptr off;
+	int8 one_byte;
+
+	for(off = 0; off < n; off += page_size) {
+		int32 errval = runtime·mincore((int8 *)v + off, page_size, (void *)&one_byte);
+		// errval is 0 if success, or -(error_code) if error.
+		if (errval == 0 || errval != -ENOMEM)
+			return 0;
+	}
+	USED(v);
+	USED(n);
+	return 1;
+}
+
+
 void*
 runtime·SysAlloc(uintptr n)
 {
@@ -39,20 +63,21 @@ runtime·SysFree(void *v, uintptr 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(sizeof(void*) == 8)
 		return v;
 	
-	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+	p = runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+	if(p < (void*)4096) {
+		return nil;
+	}
+	return p;
 }
 
-enum
-{
-	ENOMEM = 12,
-};
-
 void
 runtime·SysMap(void *v, uintptr n)
 {
@@ -63,6 +88,13 @@ 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 != v && addrspace_free(v, n)) {
+			// On some systems, mmap ignores v without
+			// MAP_FIXED, so retry if the address space is free.
+			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·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
 			runtime·throw("runtime: address space conflict");
@@ -71,7 +103,7 @@ 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)
+	if(p == (void*)ENOMEM)
 		runtime·throw("runtime: out of memory");
 	if(p != v)
 		runtime·throw("runtime: cannot map pages in arena address space");