зеркало из https://github.com/mozilla/gecko-dev.git
84 строки
3.0 KiB
C++
84 строки
3.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifdef XP_LINUX
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# include "mozilla/TaggedAnonymousMemory.h"
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# include <sys/types.h>
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# include <sys/mman.h>
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# include <sys/prctl.h>
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# include <sys/syscall.h>
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# include <unistd.h>
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# include "mozilla/Assertions.h"
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// These constants are copied from <sys/prctl.h>, because the headers
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// used for building may not have them even though the running kernel
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// supports them.
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# ifndef PR_SET_VMA
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# define PR_SET_VMA 0x53564d41
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# endif
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# ifndef PR_SET_VMA_ANON_NAME
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# define PR_SET_VMA_ANON_NAME 0
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# endif
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namespace mozilla {
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// Returns 0 for success and -1 (with errno) for error.
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static int TagAnonymousMemoryAligned(const void* aPtr, size_t aLength,
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const char* aTag) {
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return prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME,
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reinterpret_cast<unsigned long>(aPtr), aLength,
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reinterpret_cast<unsigned long>(aTag));
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}
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// On some architectures, it's possible for the page size to be larger
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// than the PAGE_SIZE we were compiled with. This computes the
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// equivalent of PAGE_MASK.
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static uintptr_t GetPageMask() {
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static uintptr_t mask = 0;
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if (mask == 0) {
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uintptr_t pageSize = sysconf(_SC_PAGESIZE);
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mask = ~(pageSize - 1);
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MOZ_ASSERT((pageSize & (pageSize - 1)) == 0,
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"Page size must be a power of 2!");
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}
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return mask;
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}
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} // namespace mozilla
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void MozTagAnonymousMemory(const void* aPtr, size_t aLength, const char* aTag) {
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// The kernel will round up the end of the range to the next page
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// boundary if it's not aligned (comments indicate this behavior is
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// based on that of madvise), but it will reject the request if the
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// start is not aligned. We therefore round down the start address
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// and adjust the length accordingly.
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uintptr_t addr = reinterpret_cast<uintptr_t>(aPtr);
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uintptr_t end = addr + aLength;
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uintptr_t addrRounded = addr & mozilla::GetPageMask();
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const void* ptrRounded = reinterpret_cast<const void*>(addrRounded);
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// Ignore the return value. TagAnonymousMemoryAligned will harmlessly fail on
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// kernels without CONFIG_ANON_VMA_NAME.
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mozilla::TagAnonymousMemoryAligned(ptrRounded, end - addrRounded, aTag);
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}
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void* MozTaggedAnonymousMmap(void* aAddr, size_t aLength, int aProt, int aFlags,
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int aFd, off_t aOffset, const char* aTag) {
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void* mapped = mmap(aAddr, aLength, aProt, aFlags, aFd, aOffset);
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if ((aFlags & MAP_ANONYMOUS) == MAP_ANONYMOUS && mapped != MAP_FAILED) {
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// Ignore the return value. TagAnonymousMemoryAligned will harmlessly fail
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// on kernels without CONFIG_ANON_VMA_NAME.
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mozilla::TagAnonymousMemoryAligned(mapped, aLength, aTag);
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}
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return mapped;
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}
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#endif // XP_LINUX
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