mfbt/TaggedAnonymousMemory.h
author Narcis Beleuzu <nbeleuzu@mozilla.com>
Thu, 21 Jun 2018 16:51:55 +0300
changeset 477502 59322b179c0fdb4423d42b624da7bf64ee5a2327
parent 210104 7958c801c56ae9b74aac24d854b6cc37a28376ad
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Backed out 4 changesets (bug 1268889) for Windows GTest failures. CLOSED TREE Backed out changeset da427a67372e (bug 1268889) Backed out changeset 97528847b7b7 (bug 1268889) Backed out changeset b2320061fbcb (bug 1268889) Backed out changeset dd3b7047ea6f (bug 1268889)

/* -*- 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"

#ifdef ANDROID

#ifdef __cplusplus
extern "C" {
#endif

MFBT_API void
MozTagAnonymousMemory(const void* aPtr, size_t aLength, const char* aTag);

MFBT_API void*
MozTaggedAnonymousMmap(void* aAddr, size_t aLength, int aProt, int aFlags,
                         int aFd, off_t aOffset, const char* aTag);

MFBT_API int
MozTaggedMemoryIsSupported(void);

#ifdef __cplusplus
} // extern "C"
#endif

#else // ANDROID

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 // ANDROID

#endif // !XP_WIN

#endif // mozilla_TaggedAnonymousMemory_h