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//===-- tsd_exclusive.h -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef SCUDO_TSD_EXCLUSIVE_H_
#define SCUDO_TSD_EXCLUSIVE_H_
#include "tsd.h"
#include <pthread.h>
namespace scudo {
enum class ThreadState : u8 {
NotInitialized = 0,
Initialized,
TornDown,
};
template <class Allocator> void teardownThread(void *Ptr);
template <class Allocator> struct TSDRegistryExT {
void initLinkerInitialized(Allocator *Instance) {
Instance->initLinkerInitialized();
CHECK_EQ(pthread_key_create(&PThreadKey, teardownThread<Allocator>), 0);
FallbackTSD = reinterpret_cast<TSD<Allocator> *>(
map(nullptr, sizeof(TSD<Allocator>), "scudo:tsd"));
FallbackTSD->initLinkerInitialized(Instance);
Initialized = true;
}
void init(Allocator *Instance) {
memset(this, 0, sizeof(*this));
initLinkerInitialized(Instance);
}
void unmapTestOnly() {
unmap(reinterpret_cast<void *>(FallbackTSD), sizeof(TSD<Allocator>));
}
ALWAYS_INLINE void initThreadMaybe(Allocator *Instance, bool MinimalInit) {
if (LIKELY(State != ThreadState::NotInitialized))
return;
initThread(Instance, MinimalInit);
}
ALWAYS_INLINE TSD<Allocator> *getTSDAndLock(bool *UnlockRequired) {
if (LIKELY(State == ThreadState::Initialized &&
!atomic_load(&Disabled, memory_order_acquire))) {
*UnlockRequired = false;
return &ThreadTSD;
}
DCHECK(FallbackTSD);
FallbackTSD->lock();
*UnlockRequired = true;
return FallbackTSD;
}
// To disable the exclusive TSD registry, we effectively lock the fallback TSD
// and force all threads to attempt to use it instead of their local one.
void disable() {
FallbackTSD->lock();
atomic_store(&Disabled, 1U, memory_order_release);
}
void enable() {
atomic_store(&Disabled, 0U, memory_order_release);
FallbackTSD->unlock();
}
private:
void initOnceMaybe(Allocator *Instance) {
ScopedLock L(Mutex);
if (LIKELY(Initialized))
return;
initLinkerInitialized(Instance); // Sets Initialized.
}
// Using minimal initialization allows for global initialization while keeping
// the thread specific structure untouched. The fallback structure will be
// used instead.
NOINLINE void initThread(Allocator *Instance, bool MinimalInit) {
initOnceMaybe(Instance);
if (UNLIKELY(MinimalInit))
return;
CHECK_EQ(
pthread_setspecific(PThreadKey, reinterpret_cast<void *>(Instance)), 0);
ThreadTSD.initLinkerInitialized(Instance);
State = ThreadState::Initialized;
}
pthread_key_t PThreadKey;
bool Initialized;
atomic_u8 Disabled;
TSD<Allocator> *FallbackTSD;
HybridMutex Mutex;
static THREADLOCAL ThreadState State;
static THREADLOCAL TSD<Allocator> ThreadTSD;
friend void teardownThread<Allocator>(void *Ptr);
};
template <class Allocator>
THREADLOCAL TSD<Allocator> TSDRegistryExT<Allocator>::ThreadTSD;
template <class Allocator>
THREADLOCAL ThreadState TSDRegistryExT<Allocator>::State;
template <class Allocator> void teardownThread(void *Ptr) {
typedef TSDRegistryExT<Allocator> TSDRegistryT;
Allocator *Instance = reinterpret_cast<Allocator *>(Ptr);
// The glibc POSIX thread-local-storage deallocation routine calls user
// provided destructors in a loop of PTHREAD_DESTRUCTOR_ITERATIONS.
// We want to be called last since other destructors might call free and the
// like, so we wait until PTHREAD_DESTRUCTOR_ITERATIONS before draining the
// quarantine and swallowing the cache.
if (TSDRegistryT::ThreadTSD.DestructorIterations > 1) {
TSDRegistryT::ThreadTSD.DestructorIterations--;
// If pthread_setspecific fails, we will go ahead with the teardown.
if (LIKELY(pthread_setspecific(Instance->getTSDRegistry()->PThreadKey,
Ptr) == 0))
return;
}
TSDRegistryT::ThreadTSD.commitBack(Instance);
TSDRegistryT::State = ThreadState::TornDown;
}
} // namespace scudo
#endif // SCUDO_TSD_EXCLUSIVE_H_
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