forked from mirrors/gecko-dev
fbd03780ee
MozTaggedMemoryIsSupported doesn't work under ASAN because it tries to prctl the nullptr page. It should be harmless to simply call prctl and ignore the error. Depends on D195064 Differential Revision: https://phabricator.services.mozilla.com/D195065
83 lines
3 KiB
C++
83 lines
3 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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