msan_thread.cpp
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#include "msan.h"
#include "msan_thread.h"
#include "msan_interface_internal.h"
#include "sanitizer_common/sanitizer_tls_get_addr.h"
namespace __msan {
MsanThread *MsanThread::Create(thread_callback_t start_routine,
void *arg) {
uptr PageSize = GetPageSizeCached();
uptr size = RoundUpTo(sizeof(MsanThread), PageSize);
MsanThread *thread = (MsanThread*)MmapOrDie(size, __func__);
thread->start_routine_ = start_routine;
thread->arg_ = arg;
thread->destructor_iterations_ = GetPthreadDestructorIterations();
return thread;
}
void MsanThread::SetThreadStackAndTls() {
uptr tls_size = 0;
uptr stack_size = 0;
GetThreadStackAndTls(IsMainThread(), &stack_.bottom, &stack_size, &tls_begin_,
&tls_size);
stack_.top = stack_.bottom + stack_size;
tls_end_ = tls_begin_ + tls_size;
int local;
CHECK(AddrIsInStack((uptr)&local));
}
void MsanThread::ClearShadowForThreadStackAndTLS() {
__msan_unpoison((void *)stack_.bottom, stack_.top - stack_.bottom);
if (tls_begin_ != tls_end_)
__msan_unpoison((void *)tls_begin_, tls_end_ - tls_begin_);
DTLS *dtls = DTLS_Get();
CHECK_NE(dtls, 0);
for (uptr i = 0; i < dtls->dtv_size; ++i)
__msan_unpoison((void *)(dtls->dtv[i].beg), dtls->dtv[i].size);
}
void MsanThread::Init() {
SetThreadStackAndTls();
CHECK(MEM_IS_APP(stack_.bottom));
CHECK(MEM_IS_APP(stack_.top - 1));
ClearShadowForThreadStackAndTLS();
}
void MsanThread::TSDDtor(void *tsd) {
MsanThread *t = (MsanThread*)tsd;
t->Destroy();
}
void MsanThread::Destroy() {
malloc_storage().CommitBack();
// 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();
uptr size = RoundUpTo(sizeof(MsanThread), GetPageSizeCached());
UnmapOrDie(this, size);
DTLS_Destroy();
}
thread_return_t MsanThread::ThreadStart() {
Init();
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.
return 0;
}
thread_return_t res = start_routine_(arg_);
return res;
}
MsanThread::StackBounds MsanThread::GetStackBounds() const {
if (!stack_switching_)
return {stack_.bottom, stack_.top};
const uptr cur_stack = GET_CURRENT_FRAME();
// 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 MsanThread::stack_top() { return GetStackBounds().top; }
uptr MsanThread::stack_bottom() { return GetStackBounds().bottom; }
bool MsanThread::AddrIsInStack(uptr addr) {
const auto bounds = GetStackBounds();
return addr >= bounds.bottom && addr < bounds.top;
}
void MsanThread::StartSwitchFiber(uptr bottom, uptr size) {
CHECK(!stack_switching_);
next_stack_.bottom = bottom;
next_stack_.top = bottom + size;
stack_switching_ = true;
}
void MsanThread::FinishSwitchFiber(uptr *bottom_old, uptr *size_old) {
CHECK(stack_switching_);
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;
stack_switching_ = false;
next_stack_.top = 0;
next_stack_.bottom = 0;
}
} // namespace __msan