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//===-- tsd.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_H_
#define SCUDO_TSD_H_
#include "atomic_helpers.h"
#include "common.h"
#include "mutex.h"
#include "thread_annotations.h"
#include <limits.h> // for PTHREAD_DESTRUCTOR_ITERATIONS
#include <pthread.h>
// With some build setups, this might still not be defined.
#ifndef PTHREAD_DESTRUCTOR_ITERATIONS
#define PTHREAD_DESTRUCTOR_ITERATIONS 4
#endif
namespace scudo {
template <class Allocator> struct alignas(SCUDO_CACHE_LINE_SIZE) TSD {
using ThisT = TSD<Allocator>;
u8 DestructorIterations = 0;
void init(Allocator *Instance) NO_THREAD_SAFETY_ANALYSIS {
DCHECK_EQ(DestructorIterations, 0U);
DCHECK(isAligned(reinterpret_cast<uptr>(this), alignof(ThisT)));
Instance->initCache(&Cache);
DestructorIterations = PTHREAD_DESTRUCTOR_ITERATIONS;
}
inline bool tryLock() NO_THREAD_SAFETY_ANALYSIS {
if (Mutex.tryLock()) {
atomic_store_relaxed(&Precedence, 0);
return true;
}
if (atomic_load_relaxed(&Precedence) == 0)
atomic_store_relaxed(&Precedence,
static_cast<uptr>(getMonotonicTimeFast() >>
FIRST_32_SECOND_64(16, 0)));
return false;
}
inline void lock() NO_THREAD_SAFETY_ANALYSIS {
atomic_store_relaxed(&Precedence, 0);
Mutex.lock();
}
inline void unlock() NO_THREAD_SAFETY_ANALYSIS { Mutex.unlock(); }
inline uptr getPrecedence() { return atomic_load_relaxed(&Precedence); }
void commitBack(Allocator *Instance) { Instance->commitBack(this); }
// As the comments attached to `getCache()`, the TSD doesn't always need to be
// locked. In that case, we would only skip the check before we have all TSDs
// locked in all paths.
void assertLocked(bool BypassCheck) ASSERT_CAPABILITY(Mutex) {
if (SCUDO_DEBUG && !BypassCheck)
Mutex.assertHeld();
}
// Ideally, we may want to assert that all the operations on
// Cache/QuarantineCache always have the `Mutex` acquired. However, the
// current architecture of accessing TSD is not easy to cooperate with the
// thread-safety analysis because of pointer aliasing. So now we just add the
// assertion on the getters of Cache/QuarantineCache.
//
// TODO(chiahungduan): Ideally, we want to do `Mutex.assertHeld` but acquiring
// TSD doesn't always require holding the lock. Add this assertion while the
// lock is always acquired.
typename Allocator::CacheT &getCache() REQUIRES(Mutex) { return Cache; }
typename Allocator::QuarantineCacheT &getQuarantineCache() REQUIRES(Mutex) {
return QuarantineCache;
}
private:
HybridMutex Mutex;
atomic_uptr Precedence = {};
typename Allocator::CacheT Cache GUARDED_BY(Mutex);
typename Allocator::QuarantineCacheT QuarantineCache GUARDED_BY(Mutex);
};
} // namespace scudo
#endif // SCUDO_TSD_H_
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