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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/allocator/dispatcher/tls.h"
#include <string_view>
#if USE_LOCAL_TLS_EMULATION()
#include <sys/mman.h>
#include "base/check.h"
#include "base/dcheck_is_on.h"
#include "base/debug/crash_logging.h"
#include "base/immediate_crash.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX)
#include <sys/prctl.h>
#endif
namespace base::allocator::dispatcher::internal {
namespace {
base::debug::CrashKeySize GetCrashKeySize(const std::string& crash_key_name) {
if (std::size(crash_key_name) <= 32ul) {
return base::debug::CrashKeySize::Size32;
}
if (std::size(crash_key_name) <= 64ul) {
return base::debug::CrashKeySize::Size64;
}
if (std::size(crash_key_name) <= 256ul) {
return base::debug::CrashKeySize::Size256;
}
CHECK(std::size(crash_key_name) <= 1024ul);
return base::debug::CrashKeySize::Size1024;
}
#if DCHECK_IS_ON()
void Swap(std::atomic_bool& lh_op, std::atomic_bool& rh_op) {
auto lh_op_value = lh_op.load(std::memory_order_relaxed);
auto rh_op_value = rh_op.load(std::memory_order_relaxed);
CHECK(lh_op.compare_exchange_strong(lh_op_value, rh_op_value));
CHECK(rh_op.compare_exchange_strong(rh_op_value, lh_op_value));
}
#endif
} // namespace
void* MMapAllocator::AllocateMemory(size_t size_in_bytes) {
void* const mmap_res = mmap(nullptr, size_in_bytes, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX)
#if defined(PR_SET_VMA) && defined(PR_SET_VMA_ANON_NAME)
if (mmap_res != MAP_FAILED) {
// Allow the anonymous memory region allocated by mmap(MAP_ANONYMOUS) to
// be identified in /proc/$PID/smaps. This helps improve visibility into
// Chromium's memory usage on Android.
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, mmap_res, size_in_bytes,
"tls-mmap-allocator");
}
#endif
#endif
return (mmap_res != MAP_FAILED) ? mmap_res : nullptr;
}
bool MMapAllocator::FreeMemoryForTesting(void* pointer_to_allocated,
size_t size_in_bytes) {
auto const munmap_res = munmap(pointer_to_allocated, size_in_bytes);
return (munmap_res == 0);
}
PThreadTLSSystem::PThreadTLSSystem() = default;
PThreadTLSSystem::PThreadTLSSystem(PThreadTLSSystem&& other) {
std::swap(crash_key_, other.crash_key_);
std::swap(data_access_key_, other.data_access_key_);
#if DCHECK_IS_ON()
Swap(initialized_, other.initialized_);
#endif
}
PThreadTLSSystem& PThreadTLSSystem::operator=(PThreadTLSSystem&& other) {
std::swap(crash_key_, other.crash_key_);
std::swap(data_access_key_, other.data_access_key_);
#if DCHECK_IS_ON()
Swap(initialized_, other.initialized_);
#endif
return *this;
}
bool PThreadTLSSystem::Setup(
OnThreadTerminationFunction thread_termination_function,
std::string_view instance_id) {
#if DCHECK_IS_ON()
// Initialize must happen outside of the allocation path. Therefore, it is
// secure to verify with DCHECK.
DCHECK(!initialized_.exchange(true, std::memory_order_acq_rel));
#endif
auto const key_create_res =
pthread_key_create(&data_access_key_, thread_termination_function);
// On some platforms creating a new pthread-key requires an allocation when a
// given number of keys has been created. I.e. in glibc this limit is denoted
// by PTHREAD_KEY_2NDLEVEL_SIZE. However, this value is neither present on all
// systems nor accessible from here. Hence, we do not do any checks here.
// However, we strongly recommend to setup the TLS system as early as possible
// to avoid exceeding this limit.
// Some crashes might be caused by the initialization being performed too late
// and running into the problems mentioned above. Since there's no way to
// handle this issue programmatically, we include the key into the crashpad
// report to allow for later inspection.
std::string crash_key_name = "tls_system-";
crash_key_name += instance_id;
crash_key_ = base::debug::AllocateCrashKeyString(
crash_key_name.c_str(), GetCrashKeySize(crash_key_name));
base::debug::SetCrashKeyString(crash_key_,
base::NumberToString(data_access_key_));
return (0 == key_create_res);
}
bool PThreadTLSSystem::TearDownForTesting() {
#if DCHECK_IS_ON()
// TearDownForTesting must happen outside of the allocation path. Therefore,
// it is secure to verify with DCHECK.
DCHECK(initialized_.exchange(false, std::memory_order_acq_rel));
#endif
base::debug::ClearCrashKeyString(crash_key_);
crash_key_ = nullptr;
auto const key_delete_res = pthread_key_delete(data_access_key_);
return (0 == key_delete_res);
}
void* PThreadTLSSystem::GetThreadSpecificData() {
#if DCHECK_IS_ON()
if (!initialized_.load(std::memory_order_acquire)) {
return nullptr;
}
#endif
return pthread_getspecific(data_access_key_);
}
bool PThreadTLSSystem::SetThreadSpecificData(void* data) {
#if DCHECK_IS_ON()
if (!initialized_.load(std::memory_order_acquire)) {
return false;
}
#endif
return (0 == pthread_setspecific(data_access_key_, data));
}
} // namespace base::allocator::dispatcher::internal
#endif // USE_LOCAL_TLS_EMULATION()
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