gecko-dev/layout/base/nsPresArena.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=2 sw=2 et tw=78:
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Steve Clark <buster@netscape.com>
* Håkan Waara <hwaara@chello.se>
* Dan Rosen <dr@netscape.com>
* Daniel Glazman <glazman@netscape.com>
* Mats Palmgren <mats.palmgren@bredband.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK *****
*/
/* arena allocation for the frame tree and closely-related objects */
#include "nsPresArena.h"
#include "nsCRT.h"
#include "nsDebug.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "prmem.h"
#include "prinit.h"
#include "prlog.h"
#ifdef MOZ_CRASHREPORTER
#include "nsICrashReporter.h"
#include "nsCOMPtr.h"
#include "nsServiceManagerUtils.h"
#include "nsPrintfCString.h"
#endif
// Even on 32-bit systems, we allocate objects from the frame arena
// that require 8-byte alignment. The cast to PRUword is needed
// because plarena isn't as careful about mask construction as it
// ought to be.
#define ALIGN_SHIFT 3
#define PL_ARENA_CONST_ALIGN_MASK ((PRUword(1) << ALIGN_SHIFT) - 1)
#include "plarena.h"
#ifdef _WIN32
# include <windows.h>
#else
# include <unistd.h>
# include <sys/mman.h>
# ifndef MAP_ANON
# ifdef MAP_ANONYMOUS
# define MAP_ANON MAP_ANONYMOUS
# else
# error "Don't know how to get anonymous memory"
# endif
# endif
#endif
#ifndef DEBUG_TRACEMALLOC_PRESARENA
// Size to use for PLArena block allocations.
static const size_t ARENA_PAGE_SIZE = 4096;
// Freed memory is filled with a poison value, which we arrange to
// form a pointer either to an always-unmapped region of the address
// space, or to a page that has been reserved and rendered
// inaccessible via OS primitives. See tests/TestPoisonArea.cpp for
// extensive discussion of the requirements for this page. The code
// from here to 'class FreeList' needs to be kept in sync with that
// file.
#ifdef _WIN32
static void *
ReserveRegion(PRUword region, PRUword size)
{
return VirtualAlloc((void *)region, size, MEM_RESERVE, PAGE_NOACCESS);
}
static void
ReleaseRegion(void *region, PRUword size)
{
VirtualFree(region, size, MEM_RELEASE);
}
static bool
ProbeRegion(PRUword region, PRUword size)
{
SYSTEM_INFO sinfo;
GetSystemInfo(&sinfo);
if (region >= (PRUword)sinfo.lpMaximumApplicationAddress &&
region + size >= (PRUword)sinfo.lpMaximumApplicationAddress) {
return true;
} else {
return false;
}
}
static PRUword
GetDesiredRegionSize()
{
SYSTEM_INFO sinfo;
GetSystemInfo(&sinfo);
return sinfo.dwAllocationGranularity;
}
#define RESERVE_FAILED 0
#else // Unix
static void *
ReserveRegion(PRUword region, PRUword size)
{
return mmap((caddr_t)region, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
}
static void
ReleaseRegion(void *region, PRUword size)
{
munmap((caddr_t)region, size);
}
static bool
ProbeRegion(PRUword region, PRUword size)
{
if (madvise((caddr_t)region, size, MADV_NORMAL)) {
return true;
} else {
return false;
}
}
static PRUword
GetDesiredRegionSize()
{
return sysconf(_SC_PAGESIZE);
}
#define RESERVE_FAILED MAP_FAILED
#endif // system dependencies
PR_STATIC_ASSERT(sizeof(PRUword) == 4 || sizeof(PRUword) == 8);
PR_STATIC_ASSERT(sizeof(PRUword) == sizeof(void *));
static PRUword
ReservePoisonArea(PRUword rgnsize)
{
if (sizeof(PRUword) == 8) {
// Use the hardware-inaccessible region.
// We have to avoid 64-bit constants and shifts by 32 bits, since this
// code is compiled in 32-bit mode, although it is never executed there.
return
(((PRUword(0x7FFFFFFFu) << 31) << 1 | PRUword(0xF0DEAFFFu))
& ~(rgnsize-1));
} else {
// First see if we can allocate the preferred poison address from the OS.
PRUword candidate = (0xF0DEAFFF & ~(rgnsize-1));
void *result = ReserveRegion(candidate, rgnsize);
if (result == (void *)candidate) {
// success - inaccessible page allocated
return candidate;
}
// That didn't work, so see if the preferred address is within a range
// of permanently inacessible memory.
if (ProbeRegion(candidate, rgnsize)) {
// success - selected page cannot be usable memory
if (result != RESERVE_FAILED)
ReleaseRegion(result, rgnsize);
return candidate;
}
// The preferred address is already in use. Did the OS give us a
// consolation prize?
if (result != RESERVE_FAILED) {
return PRUword(result);
}
// It didn't, so try to allocate again, without any constraint on
// the address.
result = ReserveRegion(0, rgnsize);
if (result != RESERVE_FAILED) {
return PRUword(result);
}
NS_RUNTIMEABORT("no usable poison region identified");
return 0;
}
}
static PRUword ARENA_POISON;
static PRCallOnceType ARENA_POISON_guard;
static PRStatus
ARENA_POISON_init()
{
PRUword rgnsize = GetDesiredRegionSize();
PRUword rgnbase = ReservePoisonArea(rgnsize);
if (rgnsize == 0) // can't happen
return PR_FAILURE;
ARENA_POISON = rgnbase + rgnsize/2 - 1;
#ifdef MOZ_CRASHREPORTER
nsCOMPtr<nsICrashReporter> cr =
do_GetService("@mozilla.org/toolkit/crash-reporter;1");
PRBool enabled;
if (cr && NS_SUCCEEDED(cr->GetEnabled(&enabled)) && enabled) {
cr->AnnotateCrashReport(NS_LITERAL_CSTRING("FramePoisonBase"),
nsPrintfCString(17, "%.16llx", PRUint64(rgnbase)));
cr->AnnotateCrashReport(NS_LITERAL_CSTRING("FramePoisonSize"),
nsPrintfCString("%lu", PRUint32(rgnsize)));
}
#endif
return PR_SUCCESS;
}
// All keys to this hash table fit in 32 bits (see below) so we do not
// bother actually hashing them.
namespace {
class FreeList : public PLDHashEntryHdr
{
public:
typedef PRUint32 KeyType;
nsTArray<void *> mEntries;
size_t mEntrySize;
protected:
typedef const void* KeyTypePointer;
KeyTypePointer mKey;
FreeList(KeyTypePointer aKey) : mEntrySize(0), mKey(aKey) {}
// Default copy constructor and destructor are ok.
PRBool KeyEquals(KeyTypePointer const aKey) const
{ return mKey == aKey; }
static KeyTypePointer KeyToPointer(KeyType aKey)
{ return NS_INT32_TO_PTR(aKey); }
static PLDHashNumber HashKey(KeyTypePointer aKey)
{ return NS_PTR_TO_INT32(aKey); }
enum { ALLOW_MEMMOVE = PR_FALSE };
friend class nsTHashtable<FreeList>;
};
}
struct nsPresArena::State {
nsTHashtable<FreeList> mFreeLists;
PLArenaPool mPool;
State()
{
mFreeLists.Init();
PL_INIT_ARENA_POOL(&mPool, "PresArena", ARENA_PAGE_SIZE);
PR_CallOnce(&ARENA_POISON_guard, ARENA_POISON_init);
}
~State()
{
PL_FinishArenaPool(&mPool);
}
void* Allocate(PRUint32 aCode, size_t aSize)
{
NS_ABORT_IF_FALSE(aSize > 0, "PresArena cannot allocate zero bytes");
// We only hand out aligned sizes
aSize = PL_ARENA_ALIGN(&mPool, aSize);
// If there is no free-list entry for this type already, we have
// to create one now, to record its size.
FreeList* list = mFreeLists.PutEntry(aCode);
if (!list) {
return nsnull;
}
nsTArray<void*>::index_type len = list->mEntries.Length();
if (list->mEntrySize == 0) {
NS_ABORT_IF_FALSE(len == 0, "list with entries but no recorded size");
list->mEntrySize = aSize;
} else {
NS_ABORT_IF_FALSE(list->mEntrySize == aSize,
"different sizes for same object type code");
}
void* result;
if (len > 0) {
// LIFO behavior for best cache utilization
result = list->mEntries.ElementAt(len - 1);
list->mEntries.RemoveElementAt(len - 1);
#ifdef DEBUG
{
char* p = reinterpret_cast<char*>(result);
char* limit = p + list->mEntrySize;
for (; p < limit; p += sizeof(PRUword)) {
NS_ABORT_IF_FALSE(*reinterpret_cast<PRUword*>(p) == ARENA_POISON,
"PresArena: poison overwritten");
}
}
#endif
return result;
}
// Allocate a new chunk from the arena
PL_ARENA_ALLOCATE(result, &mPool, aSize);
return result;
}
void Free(PRUint32 aCode, void* aPtr)
{
// Try to recycle this entry.
FreeList* list = mFreeLists.GetEntry(aCode);
NS_ABORT_IF_FALSE(list, "no free list for pres arena object");
NS_ABORT_IF_FALSE(list->mEntrySize > 0, "PresArena cannot free zero bytes");
char* p = reinterpret_cast<char*>(aPtr);
char* limit = p + list->mEntrySize;
for (; p < limit; p += sizeof(PRUword)) {
*reinterpret_cast<PRUword*>(p) = ARENA_POISON;
}
list->mEntries.AppendElement(aPtr);
}
};
#else
// Stub implementation that forwards everything to malloc and does not
// poison.
struct nsPresArena::State
{
void* Allocate(PRUint32 /* unused */, size_t aSize)
{
return PR_Malloc(aSize);
}
void Free(PRUint32 /* unused */, void* aPtr)
{
PR_Free(aPtr);
}
};
#endif // DEBUG_TRACEMALLOC_PRESARENA
// Public interface
nsPresArena::nsPresArena()
: mState(new nsPresArena::State())
{}
nsPresArena::~nsPresArena()
{
delete mState;
}
void*
nsPresArena::AllocateBySize(size_t aSize)
{
return mState->Allocate(PRUint32(aSize) |
PRUint32(nsQueryFrame::NON_FRAME_MARKER),
aSize);
}
void
nsPresArena::FreeBySize(size_t aSize, void* aPtr)
{
mState->Free(PRUint32(aSize) |
PRUint32(nsQueryFrame::NON_FRAME_MARKER), aPtr);
}
void*
nsPresArena::AllocateByCode(nsQueryFrame::FrameIID aCode, size_t aSize)
{
return mState->Allocate(aCode, aSize);
}
void
nsPresArena::FreeByCode(nsQueryFrame::FrameIID aCode, void* aPtr)
{
mState->Free(aCode, aPtr);
}