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115 lines
3.3 KiB
C++
115 lines
3.3 KiB
C++
// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/allocator/malloc_zone_functions_mac.h"
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#include "base/atomicops.h"
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#include "base/synchronization/lock.h"
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namespace base {
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namespace allocator {
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MallocZoneFunctions g_malloc_zones[kMaxZoneCount];
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static_assert(std::is_pod<MallocZoneFunctions>::value,
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"MallocZoneFunctions must be POD");
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void StoreZoneFunctions(const ChromeMallocZone* zone,
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MallocZoneFunctions* functions) {
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memset(functions, 0, sizeof(MallocZoneFunctions));
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functions->malloc = zone->malloc;
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functions->calloc = zone->calloc;
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functions->valloc = zone->valloc;
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functions->free = zone->free;
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functions->realloc = zone->realloc;
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functions->size = zone->size;
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CHECK(functions->malloc && functions->calloc && functions->valloc &&
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functions->free && functions->realloc && functions->size);
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// These functions might be nullptr.
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functions->batch_malloc = zone->batch_malloc;
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functions->batch_free = zone->batch_free;
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if (zone->version >= 5) {
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// Not all custom malloc zones have a memalign.
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functions->memalign = zone->memalign;
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}
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if (zone->version >= 6) {
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// This may be nullptr.
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functions->free_definite_size = zone->free_definite_size;
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}
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functions->context = zone;
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}
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namespace {
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// All modifications to g_malloc_zones are gated behind this lock.
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// Dispatch to a malloc zone does not need to acquire this lock.
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base::Lock& GetLock() {
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static base::Lock* g_lock = new base::Lock;
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return *g_lock;
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}
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void EnsureMallocZonesInitializedLocked() {
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GetLock().AssertAcquired();
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}
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int g_zone_count = 0;
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bool IsMallocZoneAlreadyStoredLocked(ChromeMallocZone* zone) {
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EnsureMallocZonesInitializedLocked();
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GetLock().AssertAcquired();
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for (int i = 0; i < g_zone_count; ++i) {
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if (g_malloc_zones[i].context == reinterpret_cast<void*>(zone))
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return true;
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}
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return false;
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}
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} // namespace
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bool StoreMallocZone(ChromeMallocZone* zone) {
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base::AutoLock l(GetLock());
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EnsureMallocZonesInitializedLocked();
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if (IsMallocZoneAlreadyStoredLocked(zone))
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return false;
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if (g_zone_count == kMaxZoneCount)
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return false;
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StoreZoneFunctions(zone, &g_malloc_zones[g_zone_count]);
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++g_zone_count;
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// No other thread can possibly see these stores at this point. The code that
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// reads these values is triggered after this function returns. so we want to
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// guarantee that they are committed at this stage"
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base::subtle::MemoryBarrier();
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return true;
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}
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bool IsMallocZoneAlreadyStored(ChromeMallocZone* zone) {
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base::AutoLock l(GetLock());
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return IsMallocZoneAlreadyStoredLocked(zone);
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}
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bool DoesMallocZoneNeedReplacing(ChromeMallocZone* zone,
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const MallocZoneFunctions* functions) {
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return IsMallocZoneAlreadyStored(zone) && zone->malloc != functions->malloc;
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}
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int GetMallocZoneCountForTesting() {
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base::AutoLock l(GetLock());
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return g_zone_count;
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}
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void ClearAllMallocZonesForTesting() {
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base::AutoLock l(GetLock());
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EnsureMallocZonesInitializedLocked();
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memset(g_malloc_zones, 0, kMaxZoneCount * sizeof(MallocZoneFunctions));
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g_zone_count = 0;
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}
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} // namespace allocator
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} // namespace base
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