Imported Upstream version 1.4upstream/1.4

1 files changed, 162 insertions, 0 deletions

diff --git a/src/runtime/mem_linux.c b/src/runtime/mem_linux.c
new file mode 100644
index 000000000..bfb405607
--- /dev/null
+++ b/src/runtime/mem_linux.c
@@ -0,0 +1,162 @@
+// 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"
+#include "textflag.h"
+
+enum
+{
+	_PAGE_SIZE = 4096,
+	EACCES = 13,
+};
+
+static int32
+addrspace_free(void *v, uintptr n)
+{
+	int32 errval;
+	uintptr chunk;
+	uintptr off;
+	
+	// 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);
+		// ENOMEM means unmapped, which is what we want.
+		// Anything else we assume means the pages are mapped.
+		if (errval != -ENOMEM)
+			return 0;
+	}
+	return 1;
+}
+
+static void *
+mmap_fixed(byte *v, uintptr n, int32 prot, int32 flags, int32 fd, uint32 offset)
+{
+	void *p;
+
+	p = runtime·mmap(v, n, prot, flags, fd, offset);
+	if(p != v && addrspace_free(v, n)) {
+		// On some systems, mmap ignores v without
+		// MAP_FIXED, so retry if the address space is free.
+		if(p > (void*)4096)
+			runtime·munmap(p, n);
+		p = runtime·mmap(v, n, prot, flags|MAP_FIXED, fd, offset);
+	}
+	return p;
+}
+
+#pragma textflag NOSPLIT
+void*
+runtime·sysAlloc(uintptr n, uint64 *stat)
+{
+	void *p;
+
+	p = runtime·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+	if(p < (void*)4096) {
+		if(p == (void*)EACCES) {
+			runtime·printf("runtime: mmap: access denied\n");
+			runtime·printf("if you're running SELinux, enable execmem for this process.\n");
+			runtime·exit(2);
+		}
+		if(p == (void*)EAGAIN) {
+			runtime·printf("runtime: mmap: too much locked memory (check 'ulimit -l').\n");
+			runtime·exit(2);
+		}
+		return nil;
+	}
+	runtime·xadd64(stat, n);
+	return p;
+}
+
+void
+runtime·SysUnused(void *v, uintptr n)
+{
+	runtime·madvise(v, n, MADV_DONTNEED);
+}
+
+void
+runtime·SysUsed(void *v, uintptr n)
+{
+	USED(v);
+	USED(n);
+}
+
+void
+runtime·SysFree(void *v, uintptr n, uint64 *stat)
+{
+	runtime·xadd64(stat, -(uint64)n);
+	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, bool *reserved)
+{
+	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
+	// 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 && n > 1LL<<32) {
+		p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+		if (p != v) {
+			if(p >= (void*)4096)
+				runtime·munmap(p, 64<<10);
+			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, bool reserved, uint64 *stat)
+{
+	void *p;
+	
+	runtime·xadd64(stat, n);
+
+	// On 64-bit, we don't actually have v reserved, so tread carefully.
+	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");
+		if(p != v) {
+			runtime·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
+			runtime·throw("runtime: address space conflict");
+		}
+		return;
+	}
+
+	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE, 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");
+}