runtime: simpler heap map, memory allocation

The old heap maps used a multilevel table, but that
was overkill: there are only 1M entries on a 32-bit
machine and we can arrange to use a dense address
range on a 64-bit machine.

The heap map is in bss.  The assumption is that if
we don't touch the pages they won't be mapped in.

Also moved some duplicated memory allocation
code out of the OS-specific files.

R=r
CC=golang-dev
https://golang.org/cl/4118042

1 files changed, 16 insertions, 5 deletions

diff --git a/src/pkg/runtime/linux/mem.c b/src/pkg/runtime/linux/mem.c
index e750f97ea2..3a83e7394b 100644
--- a/src/pkg/runtime/linux/mem.c
+++ b/src/pkg/runtime/linux/mem.c
@@ -12,12 +12,11 @@ runtime·SysAlloc(uintptr n)
 	p = runtime·mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
 	if(p < (void*)4096) {
 		if(p == (void*)EACCES) {
-			runtime·printf("mmap: access denied\n");
-			runtime·printf("If you're running SELinux, enable execmem for this process.\n");
+			runtime·printf("runtime: mmap: access denied\n");
+			runtime·printf("if you're running SELinux, enable execmem for this process.\n");
 			runtime·exit(2);
 		}
-		runtime·printf("mmap: errno=%p\n", p);
-		runtime·throw("mmap");
+		return nil;
 	}
 	return p;
 }
@@ -37,7 +36,19 @@ runtime·SysFree(void *v, uintptr n)
 	runtime·munmap(v, n);
 }
 
+void*
+runtime·SysReserve(void *v, uintptr n)
+{
+	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+}
+
 void
-runtime·SysMemInit(void)
+runtime·SysMap(void *v, uintptr n)
 {
+	void *p;
+	
+	mstats.sys += n;
+	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
+	if(p != v)
+		runtime·throw("runtime: cannot map pages in arena address space");
 }