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/* -*- 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/. */
// Some Linux kernels -- specifically, newer versions of Android and
// some B2G devices -- have a feature for assigning names to ranges of
// anonymous memory (i.e., memory that doesn't have a "name" in the
// form of an underlying mapped file). These names are reported in
// /proc/<pid>/smaps alongside system-level memory usage information
// such as Proportional Set Size (memory usage adjusted for sharing
// between processes), which allows reporting this information at a
// finer granularity than would otherwise be possible (e.g.,
// separating malloc() heap from JS heap).
//
// Existing memory can be tagged with MozTagAnonymousMemory(); it will
// tag the range of complete pages containing the given interval, so
// the results may be inexact if the range isn't page-aligned.
// MozTaggedAnonymousMmap() can be used like mmap() with an extra
// parameter, and will tag the returned memory if the mapping was
// successful (and if it was in fact anonymous).
//
// NOTE: The pointer given as the "tag" argument MUST remain valid as
// long as the mapping exists. The referenced string is read when
// /proc/<pid>/smaps or /proc/<pid>/maps is read, not when the tag is
// established, so freeing it or changing its contents will have
// unexpected results. Using a static string is probably best.
//
// Also note that this header can be used by both C and C++ code.
#ifndef mozilla_TaggedAnonymousMemory_h
#define mozilla_TaggedAnonymousMemory_h
#ifndef XP_WIN
#include <sys/types.h>
#include <sys/mman.h>
#include "mozilla/Types.h"
static inline void
MozTagAnonymousMemory(const void* aPtr, size_t aLength, const char* aTag)
{
}
static inline void*
MozTaggedAnonymousMmap(void* aAddr, size_t aLength, int aProt, int aFlags,
int aFd, off_t aOffset, const char* aTag)
{
return mmap(aAddr, aLength, aProt, aFlags, aFd, aOffset);
}
static inline int
MozTaggedMemoryIsSupported(void)
{
return 0;
}
#endif // !XP_WIN
#endif // mozilla_TaggedAnonymousMemory_h
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