Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=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
#ifndef PHC_h
#define PHC_h
#include "mozilla/Assertions.h"
#include "mozilla/Maybe.h"
#include <stdint.h>
#include <stdlib.h>
#include "mozmemory_wrap.h"
namespace mozilla {
namespace phc {
// Note: a stack trace may have no frames due to a collection problem.
//
// Also note: a more compact stack trace representation could be achieved with
// some effort.
struct StackTrace {
public:
static const size_t kMaxFrames = 16;
// The number of PCs in the stack trace.
size_t mLength;
// The PCs in the stack trace. Only the first mLength are initialized.
const void* mPcs[kMaxFrames];
public:
StackTrace() : mLength(0) {}
};
// Info from PHC about an address in memory.
class AddrInfo {
public:
enum class Kind {
// The address is not in PHC-managed memory.
Unknown = 0,
// The address is within a PHC page that has never been allocated. A crash
// involving such an address is unlikely in practice, because it would
// require the crash to happen quite early.
NeverAllocatedPage = 1,
// The address is within a PHC page that is in use.
InUsePage = 2,
// The address is within a PHC page that has been allocated and then freed.
// A crash involving such an address most likely indicates a
// use-after-free. (A sufficiently wild write -- e.g. a large buffer
// overflow -- could also trigger it, but this is less likely.)
FreedPage = 3,
// The address is within a PHC guard page. A crash involving such an
// address most likely indicates a buffer overflow. (Again, a sufficiently
// wild write could unluckily trigger it, but this is less likely.)
GuardPage = 4,
};
// The page kind.
Kind mKind;
// The starting address of the allocation.
// - Unknown | NeverAllocatedPage: nullptr.
// - InUsePage | FreedPage: the address of the allocation within the page.
// - GuardPage: the mBaseAddr value from the preceding allocation page.
const void* mBaseAddr;
// The usable size, which could be bigger than the requested size.
// - Unknown | NeverAllocatePage: 0.
// - InUsePage | FreedPage: the usable size of the allocation within the page.
// - GuardPage: the mUsableSize value from the preceding allocation page.
size_t mUsableSize;
// The allocation stack.
// - Unknown | NeverAllocatedPage: Nothing.
// - InUsePage | FreedPage: Some.
// - GuardPage: the mAllocStack value from the preceding allocation page.
mozilla::Maybe<StackTrace> mAllocStack;
// The free stack.
// - Unknown | NeverAllocatedPage | InUsePage: Nothing.
// - FreedPage: Some.
// - GuardPage: the mFreeStack value from the preceding allocation page.
mozilla::Maybe<StackTrace> mFreeStack;
// True if PHC was locked and therefore we couldn't retrive some infomation.
bool mPhcWasLocked = false;
// Default to no PHC info.
AddrInfo() : mKind(Kind::Unknown), mBaseAddr(nullptr), mUsableSize(0) {}
};
// Global instance that is retrieved by the process generating the crash report
extern AddrInfo gAddrInfo;
// If this is a PHC-handled address, return true, and if an AddrInfo is
// provided, fill in all of its fields. Otherwise, return false and leave
// AddrInfo unchanged.
MOZ_JEMALLOC_API bool IsPHCAllocation(const void*, AddrInfo*);
// Disable PHC allocations on the current thread. Only useful for tests. Note
// that PHC deallocations will still occur as needed.
MOZ_JEMALLOC_API void DisablePHCOnCurrentThread();
// Re-enable PHC allocations on the current thread. Only useful for tests.
MOZ_JEMALLOC_API void ReenablePHCOnCurrentThread();
// Test whether PHC allocations are enabled on the current thread. Only
// useful for tests.
MOZ_JEMALLOC_API bool IsPHCEnabledOnCurrentThread();
// PHC has three different states:
// * Not compiled in
// * OnlyFree - The memory allocator is hooked but new allocations
// requests will be forwarded to mozjemalloc, free() will
// correctly free any PHC allocations and realloc() will
// "move" PHC allocations to mozjemalloc allocations.
// * Enabled - Full use.
enum PHCState {
OnlyFree,
Enabled,
};
MOZ_JEMALLOC_API void SetPHCState(PHCState aState);
MOZ_JEMALLOC_API void SetPHCProbabilities(int64_t aAvgDelayFirst,
int64_t aAvgDelayNormal,
int64_t aAvgDelayPageReuse);
struct MemoryUsage {
// The amount of memory used for PHC metadata, eg information about each
// allocation including stacks.
size_t mMetadataBytes = 0;
// The amount of memory lost due to rounding allocation sizes up to the
// nearest page. AKA internal fragmentation.
size_t mFragmentationBytes = 0;
};
MOZ_JEMALLOC_API void PHCMemoryUsage(MemoryUsage& aMemoryUsage);
struct PHCStats {
size_t mSlotsAllocated = 0;
size_t mSlotsFreed = 0;
size_t mSlotsUnused = 0;
};
// Return PHC memory usage information by filling in the supplied structure.
MOZ_JEMALLOC_API void GetPHCStats(PHCStats& aStats);
} // namespace phc
} // namespace mozilla
#endif /* PHC_h */