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[dev.cc] runtime: convert mem_windows.c to Go

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R=rsc
CC=golang-codereviews
https://golang.org/cl/175000043
This commit is contained in:
Alex Brainman 2014-11-13 14:53:13 +11:00
parent e5d01a5ffc
commit a0862a175d
2 changed files with 119 additions and 132 deletions
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132
src/runtime/mem_windows.c
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@ -1,132 +0,0 @@
// 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 "os_GOOS.h"
#include "defs_GOOS_GOARCH.h"
#include "malloc.h"
#include "textflag.h"
enum {
MEM_COMMIT = 0x1000,
MEM_RESERVE = 0x2000,
MEM_DECOMMIT = 0x4000,
MEM_RELEASE = 0x8000,
PAGE_READWRITE = 0x0004,
PAGE_NOACCESS = 0x0001,
};
#pragma dynimport runtime·VirtualAlloc VirtualAlloc "kernel32.dll"
#pragma dynimport runtime·VirtualFree VirtualFree "kernel32.dll"
#pragma dynimport runtime·VirtualProtect VirtualProtect "kernel32.dll"
extern void *runtime·VirtualAlloc;
extern void *runtime·VirtualFree;
extern void *runtime·VirtualProtect;
#pragma textflag NOSPLIT
void*
runtime·sysAlloc(uintptr n, uint64 *stat)
{
runtime·xadd64(stat, n);
return runtime·stdcall4(runtime·VirtualAlloc, 0, n, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
}
void
runtime·SysUnused(void *v, uintptr n)
{
void *r;
uintptr small;
r = runtime·stdcall3(runtime·VirtualFree, (uintptr)v, n, MEM_DECOMMIT);
if(r != nil)
return;
// Decommit failed. Usual reason is that we've merged memory from two different
// VirtualAlloc calls, and Windows will only let each VirtualFree handle pages from
// a single VirtualAlloc. It is okay to specify a subset of the pages from a single alloc,
// just not pages from multiple allocs. This is a rare case, arising only when we're
// trying to give memory back to the operating system, which happens on a time
// scale of minutes. It doesn't have to be terribly fast. Instead of extra bookkeeping
// on all our VirtualAlloc calls, try freeing successively smaller pieces until
// we manage to free something, and then repeat. This ends up being O(n log n)
// in the worst case, but that's fast enough.
while(n > 0) {
small = n;
while(small >= 4096 && runtime·stdcall3(runtime·VirtualFree, (uintptr)v, small, MEM_DECOMMIT) == nil)
small = (small / 2) & ~(4096-1);
if(small < 4096)
runtime·throw("runtime: failed to decommit pages");
v = (byte*)v + small;
n -= small;
}
}
void
runtime·SysUsed(void *v, uintptr n)
{
void *r;
uintptr small;
r = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_COMMIT, PAGE_READWRITE);
if(r != v)
runtime·throw("runtime: failed to commit pages");
// Commit failed. See SysUnused.
while(n > 0) {
small = n;
while(small >= 4096 && runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, small, MEM_COMMIT, PAGE_READWRITE) == nil)
small = (small / 2) & ~(4096-1);
if(small < 4096)
runtime·throw("runtime: failed to decommit pages");
v = (byte*)v + small;
n -= small;
}
}
void
runtime·SysFree(void *v, uintptr n, uint64 *stat)
{
uintptr r;
runtime·xadd64(stat, -(uint64)n);
r = (uintptr)runtime·stdcall3(runtime·VirtualFree, (uintptr)v, 0, MEM_RELEASE);
if(r == 0)
runtime·throw("runtime: failed to release pages");
}
void
runtime·SysFault(void *v, uintptr n)
{
// SysUnused makes the memory inaccessible and prevents its reuse
runtime·SysUnused(v, n);
}
void*
runtime·SysReserve(void *v, uintptr n, bool *reserved)
{
*reserved = true;
// v is just a hint.
// First try at v.
v = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_RESERVE, PAGE_READWRITE);
if(v != nil)
return v;
// Next let the kernel choose the address.
return runtime·stdcall4(runtime·VirtualAlloc, 0, n, MEM_RESERVE, PAGE_READWRITE);
}
void
runtime·SysMap(void *v, uintptr n, bool reserved, uint64 *stat)
{
void *p;
USED(reserved);
runtime·xadd64(stat, n);
p = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_COMMIT, PAGE_READWRITE);
if(p != v)
runtime·throw("runtime: cannot map pages in arena address space");
}

119
src/runtime/mem_windows.go Normal file
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@ -0,0 +1,119 @@
// 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.
package runtime
import (
"unsafe"
)
const (
_MEM_COMMIT = 0x1000
_MEM_RESERVE = 0x2000
_MEM_DECOMMIT = 0x4000
_MEM_RELEASE = 0x8000
_PAGE_READWRITE = 0x0004
_PAGE_NOACCESS = 0x0001
)
//go:cgo_import_dynamic runtime._VirtualAlloc VirtualAlloc "kernel32.dll"
//go:cgo_import_dynamic runtime._VirtualFree VirtualFree "kernel32.dll"
//go:cgo_import_dynamic runtime._VirtualProtect VirtualProtect "kernel32.dll"
var (
_VirtualAlloc,
_VirtualFree,
_VirtualProtect stdFunction
)
//go:nosplit
func sysAlloc(n uintptr, stat *uint64) unsafe.Pointer {
xadd64(stat, int64(n))
return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
}
func sysUnused(v unsafe.Pointer, n uintptr) {
r := stdcall3(_VirtualFree, uintptr(v), n, _MEM_DECOMMIT)
if r != 0 {
return
}
// Decommit failed. Usual reason is that we've merged memory from two different
// VirtualAlloc calls, and Windows will only let each VirtualFree handle pages from
// a single VirtualAlloc. It is okay to specify a subset of the pages from a single alloc,
// just not pages from multiple allocs. This is a rare case, arising only when we're
// trying to give memory back to the operating system, which happens on a time
// scale of minutes. It doesn't have to be terribly fast. Instead of extra bookkeeping
// on all our VirtualAlloc calls, try freeing successively smaller pieces until
// we manage to free something, and then repeat. This ends up being O(n log n)
// in the worst case, but that's fast enough.
for n > 0 {
small := n
for small >= 4096 && stdcall3(_VirtualFree, uintptr(v), small, _MEM_DECOMMIT) == 0 {
small /= 2
small &^= 4096 - 1
}
if small < 4096 {
gothrow("runtime: failed to decommit pages")
}
v = add(v, small)
n -= small
}
}
func sysUsed(v unsafe.Pointer, n uintptr) {
r := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
if r != uintptr(v) {
gothrow("runtime: failed to commit pages")
}
// Commit failed. See SysUnused.
for n > 0 {
small := n
for small >= 4096 && stdcall4(_VirtualAlloc, uintptr(v), small, _MEM_COMMIT, _PAGE_READWRITE) == 0 {
small /= 2
small &^= 4096 - 1
}
if small < 4096 {
gothrow("runtime: failed to decommit pages")
}
v = add(v, small)
n -= small
}
}
func sysFree(v unsafe.Pointer, n uintptr, stat *uint64) {
xadd64(stat, -int64(n))
r := stdcall3(_VirtualFree, uintptr(v), 0, _MEM_RELEASE)
if r == 0 {
gothrow("runtime: failed to release pages")
}
}
func sysFault(v unsafe.Pointer, n uintptr) {
// SysUnused makes the memory inaccessible and prevents its reuse
sysUnused(v, n)
}
func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
*reserved = true
// v is just a hint.
// First try at v.
v = unsafe.Pointer(stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_RESERVE, _PAGE_READWRITE))
if v != nil {
return v
}
// Next let the kernel choose the address.
return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_RESERVE, _PAGE_READWRITE))
}
func sysMap(v unsafe.Pointer, n uintptr, reserved bool, stat *uint64) {
xadd64(stat, int64(n))
p := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
if p != uintptr(v) {
gothrow("runtime: cannot map pages in arena address space")
}
}