зеркало из https://github.com/mozilla/gecko-dev.git
106 строки
3.1 KiB
C++
106 строки
3.1 KiB
C++
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
||
|
|
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
||
|
|
/* This Source Code Form is subject to the terms of the Mozilla Public
|
||
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
||
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
||
|
|
|
||
|
|
#ifdef ANDROID
|
||
|
|
|
||
|
|
#include "mozilla/TaggedAnonymousMemory.h"
|
||
|
|
|
||
|
|
#include <sys/types.h>
|
||
|
|
#include <sys/mman.h>
|
||
|
|
#include <sys/prctl.h>
|
||
|
|
#include <sys/syscall.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
#include "mozilla/Assertions.h"
|
||
|
|
|
||
|
|
// These constants are copied from <sys/prctl.h>, because the headers
|
||
|
|
// used for building may not have them even though the running kernel
|
||
|
|
// supports them.
|
||
|
|
#ifndef PR_SET_VMA
|
||
|
|
#define PR_SET_VMA 0x53564d41
|
||
|
|
#endif
|
||
|
|
#ifndef PR_SET_VMA_ANON_NAME
|
||
|
|
#define PR_SET_VMA_ANON_NAME 0
|
||
|
|
#endif
|
||
|
|
|
||
|
|
namespace mozilla {
|
||
|
|
|
||
|
|
// Returns 0 for success and -1 (with errno) for error.
|
||
|
|
static int
|
||
|
|
TagAnonymousMemoryAligned(const void* aPtr, size_t aLength, const char* aTag)
|
||
|
|
{
|
||
|
|
return prctl(PR_SET_VMA,
|
||
|
|
PR_SET_VMA_ANON_NAME,
|
||
|
|
reinterpret_cast<unsigned long>(aPtr),
|
||
|
|
aLength,
|
||
|
|
reinterpret_cast<unsigned long>(aTag));
|
||
|
|
}
|
||
|
|
|
||
|
|
// On some architectures, it's possible for the page size to be larger
|
||
|
|
// than the PAGE_SIZE we were compiled with. This computes the
|
||
|
|
// equivalent of PAGE_MASK.
|
||
|
|
static uintptr_t
|
||
|
|
GetPageMask()
|
||
|
|
{
|
||
|
|
static uintptr_t mask = 0;
|
||
|
|
|
||
|
|
if (mask == 0) {
|
||
|
|
uintptr_t pageSize = sysconf(_SC_PAGESIZE);
|
||
|
|
mask = ~(pageSize - 1);
|
||
|
|
MOZ_ASSERT((pageSize & (pageSize - 1)) == 0,
|
||
|
|
"Page size must be a power of 2!");
|
||
|
|
}
|
||
|
|
return mask;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace mozilla
|
||
|
|
|
||
|
|
int
|
||
|
|
MozTaggedMemoryIsSupported(void)
|
||
|
|
{
|
||
|
|
static int supported = -1;
|
||
|
|
|
||
|
|
if (supported == -1) {
|
||
|
|
// Tagging an empty range always "succeeds" if the feature is supported,
|
||
|
|
// regardless of the start pointer.
|
||
|
|
supported = mozilla::TagAnonymousMemoryAligned(nullptr, 0, nullptr) == 0;
|
||
|
|
}
|
||
|
|
return supported;
|
||
|
|
}
|
||
|
|
|
||
|
|
void
|
||
|
|
MozTagAnonymousMemory(const void* aPtr, size_t aLength, const char* aTag)
|
||
|
|
{
|
||
|
|
if (MozTaggedMemoryIsSupported()) {
|
||
|
|
// The kernel will round up the end of the range to the next page
|
||
|
|
// boundary if it's not aligned (comments indicate this behavior
|
||
|
|
// is based on that of madvise), but it will reject the request if
|
||
|
|
// the start is not aligned. We therefore round down the start
|
||
|
|
// address and adjust the length accordingly.
|
||
|
|
uintptr_t addr = reinterpret_cast<uintptr_t>(aPtr);
|
||
|
|
uintptr_t end = addr + aLength;
|
||
|
|
uintptr_t addrRounded = addr & mozilla::GetPageMask();
|
||
|
|
const void* ptrRounded = reinterpret_cast<const void*>(addrRounded);
|
||
|
|
|
||
|
|
mozilla::TagAnonymousMemoryAligned(ptrRounded, end - addrRounded, aTag);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void*
|
||
|
|
MozTaggedAnonymousMmap(void* aAddr, size_t aLength, int aProt, int aFlags,
|
||
|
|
int aFd, off_t aOffset, const char* aTag)
|
||
|
|
{
|
||
|
|
void* mapped = mmap(aAddr, aLength, aProt, aFlags, aFd, aOffset);
|
||
|
|
if (MozTaggedMemoryIsSupported() &&
|
||
|
|
(aFlags & MAP_ANONYMOUS) == MAP_ANONYMOUS &&
|
||
|
|
mapped != MAP_FAILED) {
|
||
|
|
mozilla::TagAnonymousMemoryAligned(mapped, aLength, aTag);
|
||
|
|
}
|
||
|
|
return mapped;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif // ANDROID
|