mirror of https://github.com/golang/go.git
121 lines
3.4 KiB
C
121 lines
3.4 KiB
C
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "runtime.h"
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#include "arch_GOARCH.h"
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#include "os_GOOS.h"
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#include "defs_GOOS_GOARCH.h"
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#include "malloc.h"
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#include "textflag.h"
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enum {
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MEM_COMMIT = 0x1000,
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MEM_RESERVE = 0x2000,
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MEM_DECOMMIT = 0x4000,
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MEM_RELEASE = 0x8000,
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PAGE_READWRITE = 0x0004,
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PAGE_NOACCESS = 0x0001,
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};
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#pragma dynimport runtime·VirtualAlloc VirtualAlloc "kernel32.dll"
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#pragma dynimport runtime·VirtualFree VirtualFree "kernel32.dll"
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#pragma dynimport runtime·VirtualProtect VirtualProtect "kernel32.dll"
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extern void *runtime·VirtualAlloc;
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extern void *runtime·VirtualFree;
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extern void *runtime·VirtualProtect;
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#pragma textflag NOSPLIT
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void*
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runtime·sysAlloc(uintptr n, uint64 *stat)
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{
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runtime·xadd64(stat, n);
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return runtime·stdcall4(runtime·VirtualAlloc, 0, n, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
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}
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void
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runtime·SysUnused(void *v, uintptr n)
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{
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void *r;
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uintptr small;
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r = runtime·stdcall3(runtime·VirtualFree, (uintptr)v, n, MEM_DECOMMIT);
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if(r != nil)
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return;
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// Decommit failed. Usual reason is that we've merged memory from two different
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// VirtualAlloc calls, and Windows will only let each VirtualFree handle pages from
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// a single VirtualAlloc. It is okay to specify a subset of the pages from a single alloc,
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// just not pages from multiple allocs. This is a rare case, arising only when we're
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// trying to give memory back to the operating system, which happens on a time
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// scale of minutes. It doesn't have to be terribly fast. Instead of extra bookkeeping
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// on all our VirtualAlloc calls, try freeing successively smaller pieces until
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// we manage to free something, and then repeat. This ends up being O(n log n)
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// in the worst case, but that's fast enough.
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while(n > 0) {
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small = n;
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while(small >= 4096 && runtime·stdcall3(runtime·VirtualFree, (uintptr)v, small, MEM_DECOMMIT) == nil)
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small = (small / 2) & ~(4096-1);
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if(small < 4096)
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runtime·throw("runtime: failed to decommit pages");
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v = (byte*)v + small;
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n -= small;
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}
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}
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void
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runtime·SysUsed(void *v, uintptr n)
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{
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void *r;
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r = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_COMMIT, PAGE_READWRITE);
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if(r != v)
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runtime·throw("runtime: failed to commit pages");
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}
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void
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runtime·SysFree(void *v, uintptr n, uint64 *stat)
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{
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uintptr r;
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runtime·xadd64(stat, -(uint64)n);
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r = (uintptr)runtime·stdcall3(runtime·VirtualFree, (uintptr)v, 0, MEM_RELEASE);
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if(r == 0)
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runtime·throw("runtime: failed to release pages");
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}
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void
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runtime·SysFault(void *v, uintptr n)
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{
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// SysUnused makes the memory inaccessible and prevents its reuse
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runtime·SysUnused(v, n);
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}
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void*
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runtime·SysReserve(void *v, uintptr n, bool *reserved)
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{
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*reserved = true;
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// v is just a hint.
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// First try at v.
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v = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_RESERVE, PAGE_READWRITE);
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if(v != nil)
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return v;
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// Next let the kernel choose the address.
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return runtime·stdcall4(runtime·VirtualAlloc, 0, n, MEM_RESERVE, PAGE_READWRITE);
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}
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void
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runtime·SysMap(void *v, uintptr n, bool reserved, uint64 *stat)
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{
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void *p;
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USED(reserved);
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runtime·xadd64(stat, n);
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p = runtime·stdcall4(runtime·VirtualAlloc, (uintptr)v, n, MEM_COMMIT, PAGE_READWRITE);
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if(p != v)
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runtime·throw("runtime: cannot map pages in arena address space");
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}
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