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//===-- asan_thread.cc ----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Thread-related code.
//===----------------------------------------------------------------------===//
#include "asan_allocator.h"
#include "asan_interceptors.h"
#include "asan_poisoning.h"
#include "asan_stack.h"
#include "asan_thread.h"
#include "asan_mapping.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_placement_new.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
#include "sanitizer_common/sanitizer_tls_get_addr.h"
#include "lsan/lsan_common.h"
namespace __asan {
// AsanThreadContext implementation.
void AsanThreadContext::OnCreated(void *arg) {
CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs*>(arg);
if (args->stack)
stack_id = StackDepotPut(*args->stack);
thread = args->thread;
thread->set_context(this);
}
void AsanThreadContext::OnFinished() {
// Drop the link to the AsanThread object.
thread = nullptr;
}
// MIPS requires aligned address
static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)];
static ThreadRegistry *asan_thread_registry;
static BlockingMutex mu_for_thread_context(LINKER_INITIALIZED);
static LowLevelAllocator allocator_for_thread_context;
static ThreadContextBase *GetAsanThreadContext(u32 tid) {
BlockingMutexLock lock(&mu_for_thread_context);
return new(allocator_for_thread_context) AsanThreadContext(tid);
}
ThreadRegistry &asanThreadRegistry() {
static bool initialized;
// Don't worry about thread_safety - this should be called when there is
// a single thread.
if (!initialized) {
// Never reuse ASan threads: we store pointer to AsanThreadContext
// in TSD and can't reliably tell when no more TSD destructors will
// be called. It would be wrong to reuse AsanThreadContext for another
// thread before all TSD destructors will be called for it.
asan_thread_registry = new(thread_registry_placeholder) ThreadRegistry(
GetAsanThreadContext, kMaxNumberOfThreads, kMaxNumberOfThreads);
initialized = true;
}
return *asan_thread_registry;
}
AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
return static_cast<AsanThreadContext *>(
asanThreadRegistry().GetThreadLocked(tid));
}
// AsanThread implementation.
AsanThread *AsanThread::Create(thread_callback_t start_routine, void *arg,
u32 parent_tid, StackTrace *stack,
bool detached) {
uptr PageSize = GetPageSizeCached();
uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
AsanThread *thread = (AsanThread*)MmapOrDie(size, __func__);
thread->start_routine_ = start_routine;
thread->arg_ = arg;
AsanThreadContext::CreateThreadContextArgs args = {thread, stack};
asanThreadRegistry().CreateThread(*reinterpret_cast<uptr *>(thread), detached,
parent_tid, &args);
return thread;
}
void AsanThread::TSDDtor(void *tsd) {
AsanThreadContext *context = (AsanThreadContext*)tsd;
VReport(1, "T%d TSDDtor\n", context->tid);
if (context->thread)
context->thread->Destroy();
}
void AsanThread::Destroy() {
int tid = this->tid();
VReport(1, "T%d exited\n", tid);
malloc_storage().CommitBack();
if (common_flags()->use_sigaltstack) UnsetAlternateSignalStack();
asanThreadRegistry().FinishThread(tid);
FlushToDeadThreadStats(&stats_);
// We also clear the shadow on thread destruction because
// some code may still be executing in later TSD destructors
// and we don't want it to have any poisoned stack.
ClearShadowForThreadStackAndTLS();
DeleteFakeStack(tid);
uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
UnmapOrDie(this, size);
DTLS_Destroy();
}
void AsanThread::StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom,
uptr size) {
if (atomic_load(&stack_switching_, memory_order_relaxed)) {
Report("ERROR: starting fiber switch while in fiber switch\n");
Die();
}
next_stack_bottom_ = bottom;
next_stack_top_ = bottom + size;
atomic_store(&stack_switching_, 1, memory_order_release);
FakeStack *current_fake_stack = fake_stack_;
if (fake_stack_save)
*fake_stack_save = fake_stack_;
fake_stack_ = nullptr;
SetTLSFakeStack(nullptr);
// if fake_stack_save is null, the fiber will die, delete the fakestack
if (!fake_stack_save && current_fake_stack)
current_fake_stack->Destroy(this->tid());
}
void AsanThread::FinishSwitchFiber(FakeStack *fake_stack_save,
uptr *bottom_old,
uptr *size_old) {
if (!atomic_load(&stack_switching_, memory_order_relaxed)) {
Report("ERROR: finishing a fiber switch that has not started\n");
Die();
}
if (fake_stack_save) {
SetTLSFakeStack(fake_stack_save);
fake_stack_ = fake_stack_save;
}
if (bottom_old)
*bottom_old = stack_bottom_;
if (size_old)
*size_old = stack_top_ - stack_bottom_;
stack_bottom_ = next_stack_bottom_;
stack_top_ = next_stack_top_;
atomic_store(&stack_switching_, 0, memory_order_release);
next_stack_top_ = 0;
next_stack_bottom_ = 0;
}
inline AsanThread::StackBounds AsanThread::GetStackBounds() const {
if (!atomic_load(&stack_switching_, memory_order_acquire)) {
// Make sure the stack bounds are fully initialized.
if (stack_bottom_ >= stack_top_) return {0, 0};
return {stack_bottom_, stack_top_};
}
char local;
const uptr cur_stack = (uptr)&local;
// Note: need to check next stack first, because FinishSwitchFiber
// may be in process of overwriting stack_top_/bottom_. But in such case
// we are already on the next stack.
if (cur_stack >= next_stack_bottom_ && cur_stack < next_stack_top_)
return {next_stack_bottom_, next_stack_top_};
return {stack_bottom_, stack_top_};
}
uptr AsanThread::stack_top() {
return GetStackBounds().top;
}
uptr AsanThread::stack_bottom() {
return GetStackBounds().bottom;
}
uptr AsanThread::stack_size() {
const auto bounds = GetStackBounds();
return bounds.top - bounds.bottom;
}
// We want to create the FakeStack lazyly on the first use, but not eralier
// than the stack size is known and the procedure has to be async-signal safe.
FakeStack *AsanThread::AsyncSignalSafeLazyInitFakeStack() {
uptr stack_size = this->stack_size();
if (stack_size == 0) // stack_size is not yet available, don't use FakeStack.
return nullptr;
uptr old_val = 0;
// fake_stack_ has 3 states:
// 0 -- not initialized
// 1 -- being initialized
// ptr -- initialized
// This CAS checks if the state was 0 and if so changes it to state 1,
// if that was successful, it initializes the pointer.
if (atomic_compare_exchange_strong(
reinterpret_cast<atomic_uintptr_t *>(&fake_stack_), &old_val, 1UL,
memory_order_relaxed)) {
uptr stack_size_log = Log2(RoundUpToPowerOfTwo(stack_size));
CHECK_LE(flags()->min_uar_stack_size_log, flags()->max_uar_stack_size_log);
stack_size_log =
Min(stack_size_log, static_cast<uptr>(flags()->max_uar_stack_size_log));
stack_size_log =
Max(stack_size_log, static_cast<uptr>(flags()->min_uar_stack_size_log));
fake_stack_ = FakeStack::Create(stack_size_log);
SetTLSFakeStack(fake_stack_);
return fake_stack_;
}
return nullptr;
}
void AsanThread::Init(const InitOptions *options) {
next_stack_top_ = next_stack_bottom_ = 0;
atomic_store(&stack_switching_, false, memory_order_release);
CHECK_EQ(this->stack_size(), 0U);
SetThreadStackAndTls(options);
CHECK_GT(this->stack_size(), 0U);
CHECK(AddrIsInMem(stack_bottom_));
CHECK(AddrIsInMem(stack_top_ - 1));
ClearShadowForThreadStackAndTLS();
fake_stack_ = nullptr;
if (__asan_option_detect_stack_use_after_return)
AsyncSignalSafeLazyInitFakeStack();
int local = 0;
VReport(1, "T%d: stack [%p,%p) size 0x%zx; local=%p\n", tid(),
(void *)stack_bottom_, (void *)stack_top_, stack_top_ - stack_bottom_,
&local);
}
// Fuchsia and RTEMS don't use ThreadStart.
// asan_fuchsia.c/asan_rtems.c define CreateMainThread and
// SetThreadStackAndTls.
#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
thread_return_t AsanThread::ThreadStart(
tid_t os_id, atomic_uintptr_t *signal_thread_is_registered) {
Init();
asanThreadRegistry().StartThread(tid(), os_id, /*workerthread*/ false,
nullptr);
if (signal_thread_is_registered)
atomic_store(signal_thread_is_registered, 1, memory_order_release);
if (common_flags()->use_sigaltstack) SetAlternateSignalStack();
if (!start_routine_) {
// start_routine_ == 0 if we're on the main thread or on one of the
// OS X libdispatch worker threads. But nobody is supposed to call
// ThreadStart() for the worker threads.
CHECK_EQ(tid(), 0);
return 0;
}
thread_return_t res = start_routine_(arg_);
// On POSIX systems we defer this to the TSD destructor. LSan will consider
// the thread's memory as non-live from the moment we call Destroy(), even
// though that memory might contain pointers to heap objects which will be
// cleaned up by a user-defined TSD destructor. Thus, calling Destroy() before
// the TSD destructors have run might cause false positives in LSan.
if (!SANITIZER_POSIX)
this->Destroy();
return res;
}
AsanThread *CreateMainThread() {
AsanThread *main_thread = AsanThread::Create(
/* start_routine */ nullptr, /* arg */ nullptr, /* parent_tid */ 0,
/* stack */ nullptr, /* detached */ true);
SetCurrentThread(main_thread);
main_thread->ThreadStart(internal_getpid(),
/* signal_thread_is_registered */ nullptr);
return main_thread;
}
// This implementation doesn't use the argument, which is just passed down
// from the caller of Init (which see, above). It's only there to support
// OS-specific implementations that need more information passed through.
void AsanThread::SetThreadStackAndTls(const InitOptions *options) {
DCHECK_EQ(options, nullptr);
uptr tls_size = 0;
uptr stack_size = 0;
GetThreadStackAndTls(tid() == 0, const_cast<uptr *>(&stack_bottom_),
const_cast<uptr *>(&stack_size), &tls_begin_, &tls_size);
stack_top_ = stack_bottom_ + stack_size;
tls_end_ = tls_begin_ + tls_size;
dtls_ = DTLS_Get();
int local;
CHECK(AddrIsInStack((uptr)&local));
}
#endif // !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
void AsanThread::ClearShadowForThreadStackAndTLS() {
PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
if (tls_begin_ != tls_end_) {
uptr tls_begin_aligned = RoundDownTo(tls_begin_, SHADOW_GRANULARITY);
uptr tls_end_aligned = RoundUpTo(tls_end_, SHADOW_GRANULARITY);
FastPoisonShadowPartialRightRedzone(tls_begin_aligned,
tls_end_ - tls_begin_aligned,
tls_end_aligned - tls_end_, 0);
}
}
bool AsanThread::GetStackFrameAccessByAddr(uptr addr,
StackFrameAccess *access) {
uptr bottom = 0;
if (AddrIsInStack(addr)) {
bottom = stack_bottom();
} else if (has_fake_stack()) {
bottom = fake_stack()->AddrIsInFakeStack(addr);
CHECK(bottom);
access->offset = addr - bottom;
access->frame_pc = ((uptr*)bottom)[2];
access->frame_descr = (const char *)((uptr*)bottom)[1];
return true;
}
uptr aligned_addr = RoundDownTo(addr, SANITIZER_WORDSIZE / 8); // align addr.
uptr mem_ptr = RoundDownTo(aligned_addr, SHADOW_GRANULARITY);
u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
u8 *shadow_bottom = (u8*)MemToShadow(bottom);
while (shadow_ptr >= shadow_bottom &&
*shadow_ptr != kAsanStackLeftRedzoneMagic) {
shadow_ptr--;
mem_ptr -= SHADOW_GRANULARITY;
}
while (shadow_ptr >= shadow_bottom &&
*shadow_ptr == kAsanStackLeftRedzoneMagic) {
shadow_ptr--;
mem_ptr -= SHADOW_GRANULARITY;
}
if (shadow_ptr < shadow_bottom) {
return false;
}
uptr* ptr = (uptr*)(mem_ptr + SHADOW_GRANULARITY);
CHECK(ptr[0] == kCurrentStackFrameMagic);
access->offset = addr - (uptr)ptr;
access->frame_pc = ptr[2];
access->frame_descr = (const char*)ptr[1];
return true;
}
uptr AsanThread::GetStackVariableShadowStart(uptr addr) {
uptr bottom = 0;
if (AddrIsInStack(addr)) {
bottom = stack_bottom();
} else if (has_fake_stack()) {
bottom = fake_stack()->AddrIsInFakeStack(addr);
CHECK(bottom);
} else
return 0;
uptr aligned_addr = RoundDownTo(addr, SANITIZER_WORDSIZE / 8); // align addr.
u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
u8 *shadow_bottom = (u8*)MemToShadow(bottom);
while (shadow_ptr >= shadow_bottom &&
(*shadow_ptr != kAsanStackLeftRedzoneMagic &&
*shadow_ptr != kAsanStackMidRedzoneMagic &&
*shadow_ptr != kAsanStackRightRedzoneMagic))
shadow_ptr--;
return (uptr)shadow_ptr + 1;
}
bool AsanThread::AddrIsInStack(uptr addr) {
const auto bounds = GetStackBounds();
return addr >= bounds.bottom && addr < bounds.top;
}
static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base,
void *addr) {
AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base);
AsanThread *t = tctx->thread;
if (!t) return false;
if (t->AddrIsInStack((uptr)addr)) return true;
if (t->has_fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr))
return true;
return false;
}
AsanThread *GetCurrentThread() {
if (SANITIZER_RTEMS && !asan_inited)
return nullptr;
AsanThreadContext *context =
reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
if (!context) {
if (SANITIZER_ANDROID) {
// On Android, libc constructor is called _after_ asan_init, and cleans up
// TSD. Try to figure out if this is still the main thread by the stack
// address. We are not entirely sure that we have correct main thread
// limits, so only do this magic on Android, and only if the found thread
// is the main thread.
AsanThreadContext *tctx = GetThreadContextByTidLocked(0);
if (tctx && ThreadStackContainsAddress(tctx, &context)) {
SetCurrentThread(tctx->thread);
return tctx->thread;
}
}
return nullptr;
}
return context->thread;
}
void SetCurrentThread(AsanThread *t) {
CHECK(t->context());
VReport(2, "SetCurrentThread: %p for thread %p\n", t->context(),
(void *)GetThreadSelf());
// Make sure we do not reset the current AsanThread.
CHECK_EQ(0, AsanTSDGet());
AsanTSDSet(t->context());
CHECK_EQ(t->context(), AsanTSDGet());
}
u32 GetCurrentTidOrInvalid() {
AsanThread *t = GetCurrentThread();
return t ? t->tid() : kInvalidTid;
}
AsanThread *FindThreadByStackAddress(uptr addr) {
asanThreadRegistry().CheckLocked();
AsanThreadContext *tctx = static_cast<AsanThreadContext *>(
asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress,
(void *)addr));
return tctx ? tctx->thread : nullptr;
}
void EnsureMainThreadIDIsCorrect() {
AsanThreadContext *context =
reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
if (context && (context->tid == 0))
context->os_id = GetTid();
}
__asan::AsanThread *GetAsanThreadByOsIDLocked(tid_t os_id) {
__asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>(
__asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id));
if (!context) return nullptr;
return context->thread;
}
} // namespace __asan
// --- Implementation of LSan-specific functions --- {{{1
namespace __lsan {
bool GetThreadRangesLocked(tid_t os_id, uptr *stack_begin, uptr *stack_end,
uptr *tls_begin, uptr *tls_end, uptr *cache_begin,
uptr *cache_end, DTLS **dtls) {
__asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
if (!t) return false;
*stack_begin = t->stack_bottom();
*stack_end = t->stack_top();
*tls_begin = t->tls_begin();
*tls_end = t->tls_end();
// ASan doesn't keep allocator caches in TLS, so these are unused.
*cache_begin = 0;
*cache_end = 0;
*dtls = t->dtls();
return true;
}
void ForEachExtraStackRange(tid_t os_id, RangeIteratorCallback callback,
void *arg) {
__asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
if (t && t->has_fake_stack())
t->fake_stack()->ForEachFakeFrame(callback, arg);
}
void LockThreadRegistry() {
__asan::asanThreadRegistry().Lock();
}
void UnlockThreadRegistry() {
__asan::asanThreadRegistry().Unlock();
}
ThreadRegistry *GetThreadRegistryLocked() {
__asan::asanThreadRegistry().CheckLocked();
return &__asan::asanThreadRegistry();
}
void EnsureMainThreadIDIsCorrect() {
__asan::EnsureMainThreadIDIsCorrect();
}
} // namespace __lsan
// ---------------------- Interface ---------------- {{{1
using namespace __asan; // NOLINT
extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE
void __sanitizer_start_switch_fiber(void **fakestacksave, const void *bottom,
uptr size) {
AsanThread *t = GetCurrentThread();
if (!t) {
VReport(1, "__asan_start_switch_fiber called from unknown thread\n");
return;
}
t->StartSwitchFiber((FakeStack**)fakestacksave, (uptr)bottom, size);
}
SANITIZER_INTERFACE_ATTRIBUTE
void __sanitizer_finish_switch_fiber(void* fakestack,
const void **bottom_old,
uptr *size_old) {
AsanThread *t = GetCurrentThread();
if (!t) {
VReport(1, "__asan_finish_switch_fiber called from unknown thread\n");
return;
}
t->FinishSwitchFiber((FakeStack*)fakestack,
(uptr*)bottom_old,
(uptr*)size_old);
}
}