Initial Commit

1 files changed, 611 insertions, 0 deletions

diff --git a/absl/base/internal/malloc_hook.cc b/absl/base/internal/malloc_hook.cc
new file mode 100644
index 000000000000..d5d227a5f881
--- /dev/null
+++ b/absl/base/internal/malloc_hook.cc
@@ -0,0 +1,611 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/config.h"
+
+#if ABSL_HAVE_MMAP
+// 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:
+#define mremap glibc_mremap
+#include <sys/mman.h>
+#undef mremap
+#endif
+
+#include <cstddef>
+#include <cstdint>
+#include <algorithm>
+
+#include "absl/base/call_once.h"
+#include "absl/base/casts.h"
+#include "absl/base/internal/malloc_hook.h"
+#include "absl/base/internal/malloc_hook_invoke.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/spinlock.h"
+
+// __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
+
+namespace absl {
+namespace base_internal {
+namespace {
+
+void RemoveInitialHooksAndCallInitializers();  // below.
+
+absl::once_flag once;
+
+// 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) {
+  absl::call_once(once, RemoveInitialHooksAndCallInitializers);
+  MallocHook::InvokeNewHook(ptr, size);
+}
+
+void InitialPreMMapHook(const void* start,
+                               size_t size,
+                               int protection,
+                               int flags,
+                               int fd,
+                               off_t offset) {
+  absl::call_once(once, RemoveInitialHooksAndCallInitializers);
+  MallocHook::InvokePreMmapHook(start, size, protection, flags, fd, offset);
+}
+
+void InitialPreSbrkHook(ptrdiff_t increment) {
+  absl::call_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() {
+  ABSL_RAW_CHECK(MallocHook::RemoveNewHook(&InitialNewHook), "");
+  ABSL_RAW_CHECK(MallocHook::RemovePreMmapHook(&InitialPreMMapHook), "");
+  ABSL_RAW_CHECK(MallocHook::RemovePreSbrkHook(&InitialPreSbrkHook), "");
+}
+
+}  // namespace
+}  // namespace base_internal
+}  // namespace absl
+
+namespace absl {
+namespace base_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 absl::base_internal::SpinLock hooklist_spinlock(
+    absl::base_internal::kLinkerInitialized);
+
+template <typename T>
+bool HookList<T>::Add(T value_as_t) {
+  if (value_as_t == T()) {
+    return false;
+  }
+  absl::base_internal::SpinLockHolder l(&hooklist_spinlock);
+  // Find the first slot in data that is 0.
+  int index = 0;
+  while ((index < kHookListMaxValues) &&
+         (priv_data[index].load(std::memory_order_relaxed) != 0)) {
+    ++index;
+  }
+  if (index == kHookListMaxValues) {
+    return false;
+  }
+  int prev_num_hooks = priv_end.load(std::memory_order_acquire);
+  priv_data[index].store(reinterpret_cast<intptr_t>(value_as_t),
+                         std::memory_order_release);
+  if (prev_num_hooks <= index) {
+    priv_end.store(index + 1, std::memory_order_release);
+  }
+  return true;
+}
+
+template <typename T>
+bool HookList<T>::Remove(T value_as_t) {
+  if (value_as_t == T()) {
+    return false;
+  }
+  absl::base_internal::SpinLockHolder l(&hooklist_spinlock);
+  int hooks_end = priv_end.load(std::memory_order_acquire);
+  int index = 0;
+  while (index < hooks_end &&
+         value_as_t != reinterpret_cast<T>(
+                           priv_data[index].load(std::memory_order_acquire))) {
+    ++index;
+  }
+  if (index == hooks_end) {
+    return false;
+  }
+  priv_data[index].store(0, std::memory_order_release);
+  if (hooks_end == index + 1) {
+    // Adjust hooks_end down to the lowest possible value.
+    hooks_end = index;
+    while ((hooks_end > 0) &&
+           (priv_data[hooks_end - 1].load(std::memory_order_acquire) == 0)) {
+      --hooks_end;
+    }
+    priv_end.store(hooks_end, std::memory_order_release);
+  }
+  return true;
+}
+
+template <typename T>
+int HookList<T>::Traverse(T* output_array, int n) const {
+  int hooks_end = priv_end.load(std::memory_order_acquire);
+  int actual_hooks_end = 0;
+  for (int i = 0; i < hooks_end && n > 0; ++i) {
+    T data = reinterpret_cast<T>(priv_data[i].load(std::memory_order_acquire));
+    if (data != T()) {
+      *output_array++ = data;
+      ++actual_hooks_end;
+      --n;
+    }
+  }
+  return actual_hooks_end;
+}
+
+// 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<intptr_t>(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::SampledNewHook> sampled_new_hooks_ = INIT_HOOK_LIST;
+HookList<MallocHook::SampledDeleteHook> sampled_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_ = INIT_HOOK_LIST;
+HookList<MallocHook::MunmapReplacement> munmap_replacement_ = INIT_HOOK_LIST;
+
+#undef INIT_HOOK_LIST_WITH_VALUE
+#undef INIT_HOOK_LIST
+
+}  // namespace base_internal
+}  // namespace absl
+
+// 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) {
+  return absl::base_internal::new_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveNewHook(MallocHook_NewHook hook) {
+  return absl::base_internal::new_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddDeleteHook(MallocHook_DeleteHook hook) {
+  return absl::base_internal::delete_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveDeleteHook(MallocHook_DeleteHook hook) {
+  return absl::base_internal::delete_hooks_.Remove(hook);
+}
+
+extern "C" int MallocHook_AddSampledNewHook(MallocHook_SampledNewHook hook) {
+  return absl::base_internal::sampled_new_hooks_.Add(hook);
+}
+
+extern "C" int MallocHook_RemoveSampledNewHook(MallocHook_SampledNewHook hook) {
+  return absl::base_internal::sampled_new_hooks_.Remove(hook);
+}
+
+extern "C" int MallocHook_AddSampledDeleteHook(
+    MallocHook_SampledDeleteHook hook) {
+  return absl::base_internal::sampled_delete_hooks_.Add(hook);
+}
+
+extern "C" int MallocHook_RemoveSampledDeleteHook(
+    MallocHook_SampledDeleteHook hook) {
+  return absl::base_internal::sampled_delete_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddPreMmapHook(MallocHook_PreMmapHook hook) {
+  return absl::base_internal::premmap_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemovePreMmapHook(MallocHook_PreMmapHook hook) {
+  return absl::base_internal::premmap_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_SetMmapReplacement(MallocHook_MmapReplacement hook) {
+  // NOTE this is a best effort CHECK. Concurrent sets could succeed since
+  // this test is outside of the Add spin lock.
+  ABSL_RAW_CHECK(absl::base_internal::mmap_replacement_.empty(),
+                 "Only one MMapReplacement is allowed.");
+  return absl::base_internal::mmap_replacement_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveMmapReplacement(MallocHook_MmapReplacement hook) {
+  return absl::base_internal::mmap_replacement_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddMmapHook(MallocHook_MmapHook hook) {
+  return absl::base_internal::mmap_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveMmapHook(MallocHook_MmapHook hook) {
+  return absl::base_internal::mmap_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddMunmapHook(MallocHook_MunmapHook hook) {
+  return absl::base_internal::munmap_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveMunmapHook(MallocHook_MunmapHook hook) {
+  return absl::base_internal::munmap_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_SetMunmapReplacement(MallocHook_MunmapReplacement hook) {
+  // NOTE this is a best effort CHECK. Concurrent sets could succeed since
+  // this test is outside of the Add spin lock.
+  ABSL_RAW_CHECK(absl::base_internal::munmap_replacement_.empty(),
+                 "Only one MunmapReplacement is allowed.");
+  return absl::base_internal::munmap_replacement_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveMunmapReplacement(MallocHook_MunmapReplacement hook) {
+  return absl::base_internal::munmap_replacement_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddMremapHook(MallocHook_MremapHook hook) {
+  return absl::base_internal::mremap_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveMremapHook(MallocHook_MremapHook hook) {
+  return absl::base_internal::mremap_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddPreSbrkHook(MallocHook_PreSbrkHook hook) {
+  return absl::base_internal::presbrk_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemovePreSbrkHook(MallocHook_PreSbrkHook hook) {
+  return absl::base_internal::presbrk_hooks_.Remove(hook);
+}
+
+extern "C"
+int MallocHook_AddSbrkHook(MallocHook_SbrkHook hook) {
+  return absl::base_internal::sbrk_hooks_.Add(hook);
+}
+
+extern "C"
+int MallocHook_RemoveSbrkHook(MallocHook_SbrkHook hook) {
+  return absl::base_internal::sbrk_hooks_.Remove(hook);
+}
+
+namespace absl {
+namespace base_internal {
+
+// 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* ptr, size_t size) {
+  INVOKE_HOOKS(NewHook, new_hooks_, (ptr, size));
+}
+
+void MallocHook::InvokeDeleteHookSlow(const void* ptr) {
+  INVOKE_HOOKS(DeleteHook, delete_hooks_, (ptr));
+}
+
+void MallocHook::InvokeSampledNewHookSlow(const SampledAlloc* sampled_alloc) {
+  INVOKE_HOOKS(SampledNewHook, sampled_new_hooks_, (sampled_alloc));
+}
+
+void MallocHook::InvokeSampledDeleteHookSlow(AllocHandle handle) {
+  INVOKE_HOOKS(SampledDeleteHook, sampled_delete_hooks_, (handle));
+}
+
+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* start, size_t size) {
+  INVOKE_HOOKS(MunmapHook, munmap_hooks_, (start, size));
+}
+
+bool MallocHook::InvokeMunmapReplacementSlow(const void* start,
+                                             size_t size,
+                                             int* result) {
+  INVOKE_REPLACEMENT(MunmapReplacement, munmap_replacement_,
+                     (start, size, 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
+#undef INVOKE_REPLACEMENT
+
+}  // namespace base_internal
+}  // namespace absl
+
+ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(google_malloc);
+ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(google_malloc);
+// actual functions are in debugallocation.cc or tcmalloc.cc
+ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(malloc_hook);
+ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(malloc_hook);
+// actual functions are in this file, malloc_hook.cc, and low_level_alloc.cc
+ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(blink_malloc);
+ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(blink_malloc);
+// actual functions are in third_party/blink_headless/.../{PartitionAlloc,
+// FastMalloc}.cpp.
+
+#define ADDR_IN_ATTRIBUTE_SECTION(addr, name)                         \
+  (reinterpret_cast<uintptr_t>(ABSL_ATTRIBUTE_SECTION_START(name)) <= \
+       reinterpret_cast<uintptr_t>(addr) &&                           \
+   reinterpret_cast<uintptr_t>(addr) <                                \
+       reinterpret_cast<uintptr_t>(ABSL_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) ||
+         ADDR_IN_ATTRIBUTE_SECTION(caller, blink_malloc);
+  // 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 absl::once_flag in_hook_caller_once;
+
+static void InitializeInHookCaller() {
+  ABSL_INIT_ATTRIBUTE_SECTION_VARS(google_malloc);
+  if (ABSL_ATTRIBUTE_SECTION_START(google_malloc) ==
+      ABSL_ATTRIBUTE_SECTION_STOP(google_malloc)) {
+    ABSL_RAW_LOG(ERROR,
+                 "google_malloc section is missing, "
+                 "thus InHookCaller is broken!");
+  }
+  ABSL_INIT_ATTRIBUTE_SECTION_VARS(malloc_hook);
+  if (ABSL_ATTRIBUTE_SECTION_START(malloc_hook) ==
+      ABSL_ATTRIBUTE_SECTION_STOP(malloc_hook)) {
+    ABSL_RAW_LOG(ERROR,
+                 "malloc_hook section is missing, "
+                 "thus InHookCaller is broken!");
+  }
+  ABSL_INIT_ATTRIBUTE_SECTION_VARS(blink_malloc);
+  // The blink_malloc section is only expected to be present in binaries
+  // linking against the blink rendering engine in third_party/blink_headless.
+}
+
+// We can improve behavior/compactness of this function
+// if we pass a generic test function (with a generic arg)
+// into the implementations for get_stack_trace_fn instead of the skip_count.
+extern "C" int MallocHook_GetCallerStackTrace(
+    void** result, int max_depth, int skip_count,
+    MallocHook_GetStackTraceFn get_stack_trace_fn) {
+  if (!ABSL_HAVE_ATTRIBUTE_SECTION) {
+    // Fall back to get_stack_trace_fn 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.
+#ifdef NDEBUG
+    return get_stack_trace_fn(result, max_depth, skip_count);
+#else
+    return get_stack_trace_fn(result, max_depth, skip_count + 1);
+#endif
+    // due to -foptimize-sibling-calls in opt mode
+    // there's no need for extra frame skip here then
+  }
+  absl::call_once(in_hook_caller_once, InitializeInHookCaller);
+  // MallocHook caller determination via InHookCaller works, use it:
+  static const int kMaxSkip = 32 + 6 + 3;
+    // Constant tuned to do just one get_stack_trace_fn call below in practice
+    // and not get many frames that we don't actually need:
+    // currently max passed 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 =
+      get_stack_trace_fn(stack, kStackSize, 1);  // skip this function frame
+  if (depth == 0)
+    // silently propagate cases when get_stack_trace_fn does not work
+    return 0;
+  for (int i = depth - 1; i >= 0; --i) {  // stack[0] is our immediate caller
+    if (InHookCaller(stack[i])) {
+      i += 1;  // skip hook caller frame
+      depth -= i;  // correct depth
+      if (depth > max_depth) depth = max_depth;
+      std::copy(stack + i, stack + i + depth, result);
+      if (depth < max_depth  &&  depth + i == kStackSize) {
+        // get frames for the missing depth
+        depth += get_stack_trace_fn(result + depth, max_depth - depth,
+                                    1 + kStackSize);
+      }
+      return depth;
+    }
+  }
+  ABSL_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;
+}
+
+// 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).
+
+// The ABSL_MALLOC_HOOK_MMAP_DISABLE macro disables mmap/munmap interceptors.
+// Dynamic tools that intercept mmap/munmap can't be linked together with
+// malloc_hook interceptors. We disable the malloc_hook interceptors for the
+// widely-used dynamic tools, i.e. ThreadSanitizer and MemorySanitizer, but
+// still allow users to disable this in special cases that can't be easily
+// detected during compilation, via -DABSL_MALLOC_HOOK_MMAP_DISABLE or #define
+// ABSL_MALLOC_HOOK_MMAP_DISABLE.
+// TODO(b/62370839): Remove MALLOC_HOOK_MMAP_DISABLE in CROSSTOOL for tsan and
+// msan config; Replace MALLOC_HOOK_MMAP_DISABLE with
+// ABSL_MALLOC_HOOK_MMAP_DISABLE for other special cases.
+#if !defined(THREAD_SANITIZER) && !defined(MEMORY_SANITIZER) && \
+    !defined(ABSL_MALLOC_HOOK_MMAP_DISABLE) && defined(__linux__)
+#include "absl/base/internal/malloc_hook_mmap_linux.inc"
+
+#elif ABSL_HAVE_MMAP
+
+namespace absl {
+namespace base_internal {
+
+// static
+void* MallocHook::UnhookedMMap(void* start, size_t size, int protection,
+                               int flags, int fd, off_t offset) {
+  void* result;
+  if (!MallocHook::InvokeMmapReplacement(
+          start, size, protection, flags, fd, offset, &result)) {
+    result = mmap(start, size, protection, flags, fd, offset);
+  }
+  return result;
+}
+
+// static
+int MallocHook::UnhookedMUnmap(void* start, size_t size) {
+  int result;
+  if (!MallocHook::InvokeMunmapReplacement(start, size, &result)) {
+    result = munmap(start, size);
+  }
+  return result;
+}
+
+}  // namespace base_internal
+}  // namespace absl
+
+#endif