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// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Sanjay Ghemawat <opensource@google.com>
#include <config.h>
// Disable the glibc prototype of mremap(), as older versions of the
// system headers define this function with only four arguments,
// whereas newer versions allow an optional fifth argument:
#ifdef HAVE_MMAP
# define mremap glibc_mremap
# include <sys/mman.h>
# undef mremap
#endif
#include <stddef.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <algorithm>
#include "base/logging.h"
#include "base/spinlock.h"
#include "maybe_emergency_malloc.h"
#include "maybe_threads.h"
#include "malloc_hook-inl.h"
#include <gperftools/malloc_hook.h>
// This #ifdef should almost never be set. Set NO_TCMALLOC_SAMPLES if
// you're porting to a system where you really can't get a stacktrace.
#ifdef NO_TCMALLOC_SAMPLES
// We use #define so code compiles even if you #include stacktrace.h somehow.
# define GetStackTrace(stack, depth, skip) (0)
#else
# include <gperftools/stacktrace.h>
#endif
// __THROW is defined in glibc systems. It means, counter-intuitively,
// "This function will never throw an exception." It's an optional
// optimization tool, but we may need to use it to match glibc prototypes.
#ifndef __THROW // I guess we're not on a glibc system
# define __THROW // __THROW is just an optimization, so ok to make it ""
#endif
using std::copy;
// Declaration of default weak initialization function, that can be overridden
// by linking-in a strong definition (as heap-checker.cc does). This is
// extern "C" so that it doesn't trigger gold's --detect-odr-violations warning,
// which only looks at C++ symbols.
//
// This function is declared here as weak, and defined later, rather than a more
// straightforward simple weak definition, as a workround for an icc compiler
// issue ((Intel reference 290819). This issue causes icc to resolve weak
// symbols too early, at compile rather than link time. By declaring it (weak)
// here, then defining it below after its use, we can avoid the problem.
extern "C" {
ATTRIBUTE_WEAK void MallocHook_InitAtFirstAllocation_HeapLeakChecker();
}
namespace {
void RemoveInitialHooksAndCallInitializers(); // below.
pthread_once_t once = PTHREAD_ONCE_INIT;
// These hooks are installed in MallocHook as the only initial hooks. The first
// hook that is called will run RemoveInitialHooksAndCallInitializers (see the
// definition below) and then redispatch to any malloc hooks installed by
// RemoveInitialHooksAndCallInitializers.
//
// Note(llib): there is a possibility of a race in the event that there are
// multiple threads running before the first allocation. This is pretty
// difficult to achieve, but if it is then multiple threads may concurrently do
// allocations. The first caller will call
// RemoveInitialHooksAndCallInitializers via one of the initial hooks. A
// concurrent allocation may, depending on timing either:
// * still have its initial malloc hook installed, run that and block on waiting
// for the first caller to finish its call to
// RemoveInitialHooksAndCallInitializers, and proceed normally.
// * occur some time during the RemoveInitialHooksAndCallInitializers call, at
// which point there could be no initial hooks and the subsequent hooks that
// are about to be set up by RemoveInitialHooksAndCallInitializers haven't
// been installed yet. I think the worst we can get is that some allocations
// will not get reported to some hooks set by the initializers called from
// RemoveInitialHooksAndCallInitializers.
void InitialNewHook(const void* ptr, size_t size) {
perftools_pthread_once(&once, &RemoveInitialHooksAndCallInitializers);
MallocHook::InvokeNewHook(ptr, size);
}
void InitialPreMMapHook(const void* start,
size_t size,
int protection,
int flags,
int fd,
off_t offset) {
perftools_pthread_once(&once, &RemoveInitialHooksAndCallInitializers);
MallocHook::InvokePreMmapHook(start, size, protection, flags, fd, offset);
}
void InitialPreSbrkHook(ptrdiff_t increment) {
perftools_pthread_once(&once, &RemoveInitialHooksAndCallInitializers);
MallocHook::InvokePreSbrkHook(increment);
}
// This function is called at most once by one of the above initial malloc
// hooks. It removes all initial hooks and initializes all other clients that
// want to get control at the very first memory allocation. The initializers
// may assume that the initial malloc hooks have been removed. The initializers
// may set up malloc hooks and allocate memory.
void RemoveInitialHooksAndCallInitializers() {
RAW_CHECK(MallocHook::RemoveNewHook(&InitialNewHook), "");
RAW_CHECK(MallocHook::RemovePreMmapHook(&InitialPreMMapHook), "");
RAW_CHECK(MallocHook::RemovePreSbrkHook(&InitialPreSbrkHook), "");
// HeapLeakChecker is currently the only module that needs to get control on
// the first memory allocation, but one can add other modules by following the
// same weak/strong function pattern.
MallocHook_InitAtFirstAllocation_HeapLeakChecker();
}
} // namespace
// Weak default initialization function that must go after its use.
extern "C" void MallocHook_InitAtFirstAllocation_HeapLeakChecker() {
// Do nothing.
}
namespace base { namespace internal {
// This lock is shared between all implementations of HookList::Add & Remove.
// The potential for contention is very small. This needs to be a SpinLock and
// not a Mutex since it's possible for Mutex locking to allocate memory (e.g.,
// per-thread allocation in debug builds), which could cause infinite recursion.
static SpinLock hooklist_spinlock(base::LINKER_INITIALIZED);
template <typename T>
bool HookList<T>::Add(T value_as_t) {
AtomicWord value = bit_cast<AtomicWord>(value_as_t);
if (value == 0) {
return false;
}
SpinLockHolder l(&hooklist_spinlock);
// Find the first slot in data that is 0.
int index = 0;
while ((index < kHookListMaxValues) &&
(base::subtle::NoBarrier_Load(&priv_data[index]) != 0)) {
++index;
}
if (index == kHookListMaxValues) {
return false;
}
AtomicWord prev_num_hooks = base::subtle::Acquire_Load(&priv_end);
base::subtle::NoBarrier_Store(&priv_data[index], value);
if (prev_num_hooks <= index) {
base::subtle::NoBarrier_Store(&priv_end, index + 1);
}
return true;
}
template <typename T>
void HookList<T>::FixupPrivEndLocked() {
AtomicWord hooks_end = base::subtle::NoBarrier_Load(&priv_end);
while ((hooks_end > 0) &&
(base::subtle::NoBarrier_Load(&priv_data[hooks_end - 1]) == 0)) {
--hooks_end;
}
base::subtle::NoBarrier_Store(&priv_end, hooks_end);
}
template <typename T>
bool HookList<T>::Remove(T value_as_t) {
if (value_as_t == 0) {
return false;
}
SpinLockHolder l(&hooklist_spinlock);
AtomicWord hooks_end = base::subtle::NoBarrier_Load(&priv_end);
int index = 0;
while (index < hooks_end && value_as_t != bit_cast<T>(
base::subtle::NoBarrier_Load(&priv_data[index]))) {
++index;
}
if (index == hooks_end) {
return false;
}
base::subtle::NoBarrier_Store(&priv_data[index], 0);
FixupPrivEndLocked();
return true;
}
template <typename T>
int HookList<T>::Traverse(T* output_array, int n) const {
AtomicWord hooks_end = base::subtle::Acquire_Load(&priv_end);
int actual_hooks_end = 0;
for (int i = 0; i < hooks_end && n > 0; ++i) {
AtomicWord data = base::subtle::Acquire_Load(&priv_data[i]);
if (data != 0) {
*output_array++ = bit_cast<T>(data);
++actual_hooks_end;
--n;
}
}
return actual_hooks_end;
}
template <typename T>
T HookList<T>::ExchangeSingular(T value_as_t) {
AtomicWord value = bit_cast<AtomicWord>(value_as_t);
AtomicWord old_value;
SpinLockHolder l(&hooklist_spinlock);
old_value = base::subtle::NoBarrier_Load(&priv_data[kHookListSingularIdx]);
base::subtle::NoBarrier_Store(&priv_data[kHookListSingularIdx], value);
if (value != 0) {
base::subtle::NoBarrier_Store(&priv_end, kHookListSingularIdx + 1);
} else {
FixupPrivEndLocked();
}
return bit_cast<T>(old_value);
}
// Initialize a HookList (optionally with the given initial_value in index 0).
#define INIT_HOOK_LIST { 0 }
#define INIT_HOOK_LIST_WITH_VALUE(initial_value) \
{ 1, { reinterpret_cast<AtomicWord>(initial_value) } }
// Explicit instantiation for malloc_hook_test.cc. This ensures all the methods
// are instantiated.
template struct HookList<MallocHook::NewHook>;
HookList<MallocHook::NewHook> new_hooks_ =
INIT_HOOK_LIST_WITH_VALUE(&InitialNewHook);
HookList<MallocHook::DeleteHook> delete_hooks_ = INIT_HOOK_LIST;
HookList<MallocHook::PreMmapHook> premmap_hooks_ =
INIT_HOOK_LIST_WITH_VALUE(&InitialPreMMapHook);
HookList<MallocHook::MmapHook> mmap_hooks_ = INIT_HOOK_LIST;
HookList<MallocHook::MunmapHook> munmap_hooks_ = INIT_HOOK_LIST;
HookList<MallocHook::MremapHook> mremap_hooks_ = INIT_HOOK_LIST;
HookList<MallocHook::PreSbrkHook> presbrk_hooks_ =
INIT_HOOK_LIST_WITH_VALUE(InitialPreSbrkHook);
HookList<MallocHook::SbrkHook> sbrk_hooks_ = INIT_HOOK_LIST;
// These lists contain either 0 or 1 hooks.
HookList<MallocHook::MmapReplacement> mmap_replacement_ = { 0 };
HookList<MallocHook::MunmapReplacement> munmap_replacement_ = { 0 };
#undef INIT_HOOK_LIST_WITH_VALUE
#undef INIT_HOOK_LIST
} } // namespace base::internal
using base::internal::kHookListMaxValues;
using base::internal::new_hooks_;
using base::internal::delete_hooks_;
using base::internal::premmap_hooks_;
using base::internal::mmap_hooks_;
using base::internal::mmap_replacement_;
using base::internal::munmap_hooks_;
using base::internal::munmap_replacement_;
using base::internal::mremap_hooks_;
using base::internal::presbrk_hooks_;
using base::internal::sbrk_hooks_;
// These are available as C bindings as well as C++, hence their
// definition outside the MallocHook class.
extern "C"
int MallocHook_AddNewHook(MallocHook_NewHook hook) {
RAW_VLOG(10, "AddNewHook(%p)", hook);
return new_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveNewHook(MallocHook_NewHook hook) {
RAW_VLOG(10, "RemoveNewHook(%p)", hook);
return new_hooks_.Remove(hook);
}
extern "C"
int MallocHook_AddDeleteHook(MallocHook_DeleteHook hook) {
RAW_VLOG(10, "AddDeleteHook(%p)", hook);
return delete_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveDeleteHook(MallocHook_DeleteHook hook) {
RAW_VLOG(10, "RemoveDeleteHook(%p)", hook);
return delete_hooks_.Remove(hook);
}
extern "C"
int MallocHook_AddPreMmapHook(MallocHook_PreMmapHook hook) {
RAW_VLOG(10, "AddPreMmapHook(%p)", hook);
return premmap_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemovePreMmapHook(MallocHook_PreMmapHook hook) {
RAW_VLOG(10, "RemovePreMmapHook(%p)", hook);
return premmap_hooks_.Remove(hook);
}
extern "C"
int MallocHook_SetMmapReplacement(MallocHook_MmapReplacement hook) {
RAW_VLOG(10, "SetMmapReplacement(%p)", hook);
// NOTE this is a best effort CHECK. Concurrent sets could succeed since
// this test is outside of the Add spin lock.
RAW_CHECK(mmap_replacement_.empty(), "Only one MMapReplacement is allowed.");
return mmap_replacement_.Add(hook);
}
extern "C"
int MallocHook_RemoveMmapReplacement(MallocHook_MmapReplacement hook) {
RAW_VLOG(10, "RemoveMmapReplacement(%p)", hook);
return mmap_replacement_.Remove(hook);
}
extern "C"
int MallocHook_AddMmapHook(MallocHook_MmapHook hook) {
RAW_VLOG(10, "AddMmapHook(%p)", hook);
return mmap_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveMmapHook(MallocHook_MmapHook hook) {
RAW_VLOG(10, "RemoveMmapHook(%p)", hook);
return mmap_hooks_.Remove(hook);
}
extern "C"
int MallocHook_AddMunmapHook(MallocHook_MunmapHook hook) {
RAW_VLOG(10, "AddMunmapHook(%p)", hook);
return munmap_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveMunmapHook(MallocHook_MunmapHook hook) {
RAW_VLOG(10, "RemoveMunmapHook(%p)", hook);
return munmap_hooks_.Remove(hook);
}
extern "C"
int MallocHook_SetMunmapReplacement(MallocHook_MunmapReplacement hook) {
RAW_VLOG(10, "SetMunmapReplacement(%p)", hook);
// NOTE this is a best effort CHECK. Concurrent sets could succeed since
// this test is outside of the Add spin lock.
RAW_CHECK(munmap_replacement_.empty(),
"Only one MunmapReplacement is allowed.");
return munmap_replacement_.Add(hook);
}
extern "C"
int MallocHook_RemoveMunmapReplacement(MallocHook_MunmapReplacement hook) {
RAW_VLOG(10, "RemoveMunmapReplacement(%p)", hook);
return munmap_replacement_.Remove(hook);
}
extern "C"
int MallocHook_AddMremapHook(MallocHook_MremapHook hook) {
RAW_VLOG(10, "AddMremapHook(%p)", hook);
return mremap_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveMremapHook(MallocHook_MremapHook hook) {
RAW_VLOG(10, "RemoveMremapHook(%p)", hook);
return mremap_hooks_.Remove(hook);
}
extern "C"
int MallocHook_AddPreSbrkHook(MallocHook_PreSbrkHook hook) {
RAW_VLOG(10, "AddPreSbrkHook(%p)", hook);
return presbrk_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemovePreSbrkHook(MallocHook_PreSbrkHook hook) {
RAW_VLOG(10, "RemovePreSbrkHook(%p)", hook);
return presbrk_hooks_.Remove(hook);
}
extern "C"
int MallocHook_AddSbrkHook(MallocHook_SbrkHook hook) {
RAW_VLOG(10, "AddSbrkHook(%p)", hook);
return sbrk_hooks_.Add(hook);
}
extern "C"
int MallocHook_RemoveSbrkHook(MallocHook_SbrkHook hook) {
RAW_VLOG(10, "RemoveSbrkHook(%p)", hook);
return sbrk_hooks_.Remove(hook);
}
// The code below is DEPRECATED.
extern "C"
MallocHook_NewHook MallocHook_SetNewHook(MallocHook_NewHook hook) {
RAW_VLOG(10, "SetNewHook(%p)", hook);
return new_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_DeleteHook MallocHook_SetDeleteHook(MallocHook_DeleteHook hook) {
RAW_VLOG(10, "SetDeleteHook(%p)", hook);
return delete_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_PreMmapHook MallocHook_SetPreMmapHook(MallocHook_PreMmapHook hook) {
RAW_VLOG(10, "SetPreMmapHook(%p)", hook);
return premmap_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_MmapHook MallocHook_SetMmapHook(MallocHook_MmapHook hook) {
RAW_VLOG(10, "SetMmapHook(%p)", hook);
return mmap_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_MunmapHook MallocHook_SetMunmapHook(MallocHook_MunmapHook hook) {
RAW_VLOG(10, "SetMunmapHook(%p)", hook);
return munmap_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_MremapHook MallocHook_SetMremapHook(MallocHook_MremapHook hook) {
RAW_VLOG(10, "SetMremapHook(%p)", hook);
return mremap_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_PreSbrkHook MallocHook_SetPreSbrkHook(MallocHook_PreSbrkHook hook) {
RAW_VLOG(10, "SetPreSbrkHook(%p)", hook);
return presbrk_hooks_.ExchangeSingular(hook);
}
extern "C"
MallocHook_SbrkHook MallocHook_SetSbrkHook(MallocHook_SbrkHook hook) {
RAW_VLOG(10, "SetSbrkHook(%p)", hook);
return sbrk_hooks_.ExchangeSingular(hook);
}
// End of DEPRECATED code section.
// Note: embedding the function calls inside the traversal of HookList would be
// very confusing, as it is legal for a hook to remove itself and add other
// hooks. Doing traversal first, and then calling the hooks ensures we only
// call the hooks registered at the start.
#define INVOKE_HOOKS(HookType, hook_list, args) do { \
HookType hooks[kHookListMaxValues]; \
int num_hooks = hook_list.Traverse(hooks, kHookListMaxValues); \
for (int i = 0; i < num_hooks; ++i) { \
(*hooks[i])args; \
} \
} while (0)
// There should only be one replacement. Return the result of the first
// one, or false if there is none.
#define INVOKE_REPLACEMENT(HookType, hook_list, args) do { \
HookType hooks[kHookListMaxValues]; \
int num_hooks = hook_list.Traverse(hooks, kHookListMaxValues); \
return (num_hooks > 0 && (*hooks[0])args); \
} while (0)
void MallocHook::InvokeNewHookSlow(const void* p, size_t s) {
if (tcmalloc::IsEmergencyPtr(p)) {
return;
}
INVOKE_HOOKS(NewHook, new_hooks_, (p, s));
}
void MallocHook::InvokeDeleteHookSlow(const void* p) {
if (tcmalloc::IsEmergencyPtr(p)) {
return;
}
INVOKE_HOOKS(DeleteHook, delete_hooks_, (p));
}
void MallocHook::InvokePreMmapHookSlow(const void* start,
size_t size,
int protection,
int flags,
int fd,
off_t offset) {
INVOKE_HOOKS(PreMmapHook, premmap_hooks_, (start, size, protection, flags, fd,
offset));
}
void MallocHook::InvokeMmapHookSlow(const void* result,
const void* start,
size_t size,
int protection,
int flags,
int fd,
off_t offset) {
INVOKE_HOOKS(MmapHook, mmap_hooks_, (result, start, size, protection, flags,
fd, offset));
}
bool MallocHook::InvokeMmapReplacementSlow(const void* start,
size_t size,
int protection,
int flags,
int fd,
off_t offset,
void** result) {
INVOKE_REPLACEMENT(MmapReplacement, mmap_replacement_,
(start, size, protection, flags, fd, offset, result));
}
void MallocHook::InvokeMunmapHookSlow(const void* p, size_t s) {
INVOKE_HOOKS(MunmapHook, munmap_hooks_, (p, s));
}
bool MallocHook::InvokeMunmapReplacementSlow(const void* p,
size_t s,
int* result) {
INVOKE_REPLACEMENT(MunmapReplacement, munmap_replacement_, (p, s, result));
}
void MallocHook::InvokeMremapHookSlow(const void* result,
const void* old_addr,
size_t old_size,
size_t new_size,
int flags,
const void* new_addr) {
INVOKE_HOOKS(MremapHook, mremap_hooks_, (result, old_addr, old_size, new_size,
flags, new_addr));
}
void MallocHook::InvokePreSbrkHookSlow(ptrdiff_t increment) {
INVOKE_HOOKS(PreSbrkHook, presbrk_hooks_, (increment));
}
void MallocHook::InvokeSbrkHookSlow(const void* result, ptrdiff_t increment) {
INVOKE_HOOKS(SbrkHook, sbrk_hooks_, (result, increment));
}
#undef INVOKE_HOOKS
#ifndef NO_TCMALLOC_SAMPLES
DEFINE_ATTRIBUTE_SECTION_VARS(google_malloc);
DECLARE_ATTRIBUTE_SECTION_VARS(google_malloc);
// actual functions are in debugallocation.cc or tcmalloc.cc
DEFINE_ATTRIBUTE_SECTION_VARS(malloc_hook);
DECLARE_ATTRIBUTE_SECTION_VARS(malloc_hook);
// actual functions are in this file, malloc_hook.cc, and low_level_alloc.cc
#define ADDR_IN_ATTRIBUTE_SECTION(addr, name) \
(reinterpret_cast<uintptr_t>(ATTRIBUTE_SECTION_START(name)) <= \
reinterpret_cast<uintptr_t>(addr) && \
reinterpret_cast<uintptr_t>(addr) < \
reinterpret_cast<uintptr_t>(ATTRIBUTE_SECTION_STOP(name)))
// Return true iff 'caller' is a return address within a function
// that calls one of our hooks via MallocHook:Invoke*.
// A helper for GetCallerStackTrace.
static inline bool InHookCaller(const void* caller) {
return ADDR_IN_ATTRIBUTE_SECTION(caller, google_malloc) ||
ADDR_IN_ATTRIBUTE_SECTION(caller, malloc_hook);
// We can use one section for everything except tcmalloc_or_debug
// due to its special linkage mode, which prevents merging of the sections.
}
#undef ADDR_IN_ATTRIBUTE_SECTION
static bool checked_sections = false;
static inline void CheckInHookCaller() {
if (!checked_sections) {
INIT_ATTRIBUTE_SECTION_VARS(google_malloc);
if (ATTRIBUTE_SECTION_START(google_malloc) ==
ATTRIBUTE_SECTION_STOP(google_malloc)) {
RAW_LOG(ERROR, "google_malloc section is missing, "
"thus InHookCaller is broken!");
}
INIT_ATTRIBUTE_SECTION_VARS(malloc_hook);
if (ATTRIBUTE_SECTION_START(malloc_hook) ==
ATTRIBUTE_SECTION_STOP(malloc_hook)) {
RAW_LOG(ERROR, "malloc_hook section is missing, "
"thus InHookCaller is broken!");
}
checked_sections = true;
}
}
#endif // !NO_TCMALLOC_SAMPLES
// We can improve behavior/compactness of this function
// if we pass a generic test function (with a generic arg)
// into the implementations for GetStackTrace instead of the skip_count.
extern "C" int MallocHook_GetCallerStackTrace(void** result, int max_depth,
int skip_count) {
#if defined(NO_TCMALLOC_SAMPLES)
return 0;
#elif !defined(HAVE_ATTRIBUTE_SECTION_START)
// Fall back to GetStackTrace and good old but fragile frame skip counts.
// Note: this path is inaccurate when a hook is not called directly by an
// allocation function but is daisy-chained through another hook,
// search for MallocHook::(Get|Set|Invoke)* to find such cases.
return GetStackTrace(result, max_depth, skip_count + int(DEBUG_MODE));
// due to -foptimize-sibling-calls in opt mode
// there's no need for extra frame skip here then
#else
CheckInHookCaller();
// MallocHook caller determination via InHookCaller works, use it:
static const int kMaxSkip = 32 + 6 + 3;
// Constant tuned to do just one GetStackTrace call below in practice
// and not get many frames that we don't actually need:
// currently max passsed max_depth is 32,
// max passed/needed skip_count is 6
// and 3 is to account for some hook daisy chaining.
static const int kStackSize = kMaxSkip + 1;
void* stack[kStackSize];
int depth = GetStackTrace(stack, kStackSize, 1); // skip this function frame
if (depth == 0) // silenty propagate cases when GetStackTrace does not work
return 0;
for (int i = 0; i < depth; ++i) { // stack[0] is our immediate caller
if (InHookCaller(stack[i])) {
// fast-path to slow-path calls may be implemented by compiler
// as non-tail calls. Causing two functions on stack trace to be
// inside google_malloc. In such case we're skipping to
// outermost such frame since this is where malloc stack frames
// really start.
while (i + 1 < depth && InHookCaller(stack[i+1])) {
i++;
}
RAW_VLOG(10, "Found hooked allocator at %d: %p <- %p",
i, stack[i], stack[i+1]);
i += 1; // skip hook caller frame
depth -= i; // correct depth
if (depth > max_depth) depth = max_depth;
copy(stack + i, stack + i + depth, result);
if (depth < max_depth && depth + i == kStackSize) {
// get frames for the missing depth
depth +=
GetStackTrace(result + depth, max_depth - depth, 1 + kStackSize);
}
return depth;
}
}
RAW_LOG(WARNING, "Hooked allocator frame not found, returning empty trace");
// If this happens try increasing kMaxSkip
// or else something must be wrong with InHookCaller,
// e.g. for every section used in InHookCaller
// all functions in that section must be inside the same library.
return 0;
#endif
}
// On systems where we know how, we override mmap/munmap/mremap/sbrk
// to provide support for calling the related hooks (in addition,
// of course, to doing what these functions normally do).
#if defined(__linux)
# include "malloc_hook_mmap_linux.h"
#elif defined(__FreeBSD__)
# include "malloc_hook_mmap_freebsd.h"
#else
/*static*/void* MallocHook::UnhookedMMap(void *start, size_t length, int prot,
int flags, int fd, off_t offset) {
void* result;
if (!MallocHook::InvokeMmapReplacement(
start, length, prot, flags, fd, offset, &result)) {
result = mmap(start, length, prot, flags, fd, offset);
}
return result;
}
/*static*/int MallocHook::UnhookedMUnmap(void *start, size_t length) {
int result;
if (!MallocHook::InvokeMunmapReplacement(start, length, &result)) {
result = munmap(start, length);
}
return result;
}
#endif
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