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193088b246
Currently mmap returns an unsafe.Pointer that encodes OS errors as values less than 4096. In practice this is okay, but it borders on being really unsafe: for example, the value has to be checked immediately after return and if stack copying were ever to observe such a value, it would panic. It's also not remotely idiomatic. Fix this by making mmap return a separate pointer value and error, like a normal Go function. Updates #22218. Change-Id: Iefd965095ffc82cc91118872753a5d39d785c3a6 Reviewed-on: https://go-review.googlesource.com/71270 Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
64 lines
1.6 KiB
Go
64 lines
1.6 KiB
Go
// 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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package runtime
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import "unsafe"
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// Don't split the stack as this function may be invoked without a valid G,
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// which prevents us from allocating more stack.
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//go:nosplit
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func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer {
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v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
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if err != 0 {
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return nil
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}
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mSysStatInc(sysStat, n)
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return v
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}
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func sysUnused(v unsafe.Pointer, n uintptr) {
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// Linux's MADV_DONTNEED is like BSD's MADV_FREE.
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madvise(v, n, _MADV_FREE)
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}
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func sysUsed(v unsafe.Pointer, n uintptr) {
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}
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// Don't split the stack as this function may be invoked without a valid G,
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// which prevents us from allocating more stack.
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//go:nosplit
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func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) {
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mSysStatDec(sysStat, n)
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munmap(v, n)
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}
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func sysFault(v unsafe.Pointer, n uintptr) {
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mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
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}
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func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
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*reserved = true
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p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
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if err != 0 {
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return nil
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}
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return p
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}
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const (
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_ENOMEM = 12
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)
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func sysMap(v unsafe.Pointer, n uintptr, reserved bool, sysStat *uint64) {
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mSysStatInc(sysStat, n)
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p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
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if err == _ENOMEM {
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throw("runtime: out of memory")
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}
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if p != v || err != 0 {
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throw("runtime: cannot map pages in arena address space")
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}
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}
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