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//===-- scudo_tls_android.cpp -----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// Scudo thread local structure implementation for Android.
///
//===----------------------------------------------------------------------===//
#include "sanitizer_common/sanitizer_platform.h"
#if SANITIZER_LINUX && SANITIZER_ANDROID
#include "scudo_tls.h"
#include <pthread.h>
namespace __scudo {
static pthread_once_t GlobalInitialized = PTHREAD_ONCE_INIT;
static pthread_key_t PThreadKey;
static atomic_uint32_t CurrentIndex;
static ScudoTSD *TSDs;
static u32 NumberOfTSDs;
// sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used as they allocate memory.
static uptr getNumberOfCPUs() {
cpu_set_t CPUs;
CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
return CPU_COUNT(&CPUs);
}
static void initOnce() {
// Hack: TLS_SLOT_TSAN was introduced in N. To be able to use it on M for
// testing, we create an unused key. Since the key_data array follows the tls
// array, it basically gives us the extra entry we need.
// TODO(kostyak): remove and restrict to N and above.
CHECK_EQ(pthread_key_create(&PThreadKey, NULL), 0);
initScudo();
NumberOfTSDs = getNumberOfCPUs();
if (NumberOfTSDs == 0)
NumberOfTSDs = 1;
if (NumberOfTSDs > 32)
NumberOfTSDs = 32;
TSDs = reinterpret_cast<ScudoTSD *>(
MmapOrDie(sizeof(ScudoTSD) * NumberOfTSDs, "ScudoTSDs"));
for (u32 i = 0; i < NumberOfTSDs; i++)
TSDs[i].init(/*Shared=*/true);
}
void initThread(bool MinimalInit) {
pthread_once(&GlobalInitialized, initOnce);
// Initial context assignment is done in a plain round-robin fashion.
u32 Index = atomic_fetch_add(&CurrentIndex, 1, memory_order_relaxed);
ScudoTSD *TSD = &TSDs[Index % NumberOfTSDs];
*get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
}
ScudoTSD *getTSDAndLockSlow() {
ScudoTSD *TSD;
if (NumberOfTSDs > 1) {
// Go through all the contexts and find the first unlocked one.
for (u32 i = 0; i < NumberOfTSDs; i++) {
TSD = &TSDs[i];
if (TSD->tryLock()) {
*get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
return TSD;
}
}
// No luck, find the one with the lowest Precedence, and slow lock it.
u64 LowestPrecedence = UINT64_MAX;
for (u32 i = 0; i < NumberOfTSDs; i++) {
u64 Precedence = TSDs[i].getPrecedence();
if (Precedence && Precedence < LowestPrecedence) {
TSD = &TSDs[i];
LowestPrecedence = Precedence;
}
}
if (LIKELY(LowestPrecedence != UINT64_MAX)) {
TSD->lock();
*get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
return TSD;
}
}
// Last resort, stick with the current one.
TSD = reinterpret_cast<ScudoTSD *>(*get_android_tls_ptr());
TSD->lock();
return TSD;
}
} // namespace __scudo
#endif // SANITIZER_LINUX && SANITIZER_ANDROID
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