forked from OSchip/llvm-project
tsan: remember and print function that installed at_exit callbacks
Sometimes stacks for at_exit callbacks don't include any of the user functions/files. For example, a race with a global std container destructor will only contain the container type name and our at_exit_wrapper function. No signs what global variable this is. Remember and include in reports the function that installed the at_exit callback. This should give glues as to what variable is being destroyed. Depends on D114606. Reviewed By: vitalybuka, melver Differential Revision: https://reviews.llvm.org/D114607
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@ -177,6 +177,7 @@ struct ThreadSignalContext {
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struct AtExitCtx {
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void (*f)();
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void *arg;
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uptr pc;
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};
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// InterceptorContext holds all global data required for interceptors.
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@ -367,7 +368,10 @@ TSAN_INTERCEPTOR(int, pause, int fake) {
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return BLOCK_REAL(pause)(fake);
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}
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static void at_exit_wrapper() {
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// Note: we specifically call the function in such strange way
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// with "installed_at" because in reports it will appear between
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// callback frames and the frame that installed the callback.
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static void at_exit_callback_installed_at() {
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AtExitCtx *ctx;
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{
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// Ensure thread-safety.
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@ -379,15 +383,21 @@ static void at_exit_wrapper() {
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interceptor_ctx()->AtExitStack.PopBack();
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}
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Acquire(cur_thread(), (uptr)0, (uptr)ctx);
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ThreadState *thr = cur_thread();
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Acquire(thr, ctx->pc, (uptr)ctx);
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FuncEntry(thr, ctx->pc);
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((void(*)())ctx->f)();
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FuncExit(thr);
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Free(ctx);
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}
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static void cxa_at_exit_wrapper(void *arg) {
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Acquire(cur_thread(), 0, (uptr)arg);
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static void cxa_at_exit_callback_installed_at(void *arg) {
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ThreadState *thr = cur_thread();
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AtExitCtx *ctx = (AtExitCtx*)arg;
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Acquire(thr, ctx->pc, (uptr)arg);
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FuncEntry(thr, ctx->pc);
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((void(*)(void *arg))ctx->f)(ctx->arg);
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FuncExit(thr);
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Free(ctx);
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}
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@ -401,7 +411,7 @@ TSAN_INTERCEPTOR(int, atexit, void (*f)()) {
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// We want to setup the atexit callback even if we are in ignored lib
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// or after fork.
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SCOPED_INTERCEPTOR_RAW(atexit, f);
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return setup_at_exit_wrapper(thr, pc, (void(*)())f, 0, 0);
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return setup_at_exit_wrapper(thr, GET_CALLER_PC(), (void (*)())f, 0, 0);
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}
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#endif
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@ -409,7 +419,7 @@ TSAN_INTERCEPTOR(int, __cxa_atexit, void (*f)(void *a), void *arg, void *dso) {
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if (in_symbolizer())
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return 0;
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SCOPED_TSAN_INTERCEPTOR(__cxa_atexit, f, arg, dso);
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return setup_at_exit_wrapper(thr, pc, (void(*)())f, arg, dso);
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return setup_at_exit_wrapper(thr, GET_CALLER_PC(), (void (*)())f, arg, dso);
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}
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static int setup_at_exit_wrapper(ThreadState *thr, uptr pc, void(*f)(),
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@ -417,6 +427,7 @@ static int setup_at_exit_wrapper(ThreadState *thr, uptr pc, void(*f)(),
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auto *ctx = New<AtExitCtx>();
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ctx->f = f;
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ctx->arg = arg;
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ctx->pc = pc;
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Release(thr, pc, (uptr)ctx);
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// Memory allocation in __cxa_atexit will race with free during exit,
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// because we do not see synchronization around atexit callback list.
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@ -432,25 +443,27 @@ static int setup_at_exit_wrapper(ThreadState *thr, uptr pc, void(*f)(),
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// due to atexit_mu held on exit from the calloc interceptor.
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ScopedIgnoreInterceptors ignore;
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res = REAL(__cxa_atexit)((void (*)(void *a))at_exit_wrapper, 0, 0);
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res = REAL(__cxa_atexit)((void (*)(void *a))at_exit_callback_installed_at,
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0, 0);
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// Push AtExitCtx on the top of the stack of callback functions
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if (!res) {
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interceptor_ctx()->AtExitStack.PushBack(ctx);
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}
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} else {
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res = REAL(__cxa_atexit)(cxa_at_exit_wrapper, ctx, dso);
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res = REAL(__cxa_atexit)(cxa_at_exit_callback_installed_at, ctx, dso);
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}
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ThreadIgnoreEnd(thr);
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return res;
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}
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#if !SANITIZER_MAC && !SANITIZER_NETBSD
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static void on_exit_wrapper(int status, void *arg) {
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static void on_exit_callback_installed_at(int status, void *arg) {
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ThreadState *thr = cur_thread();
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uptr pc = 0;
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Acquire(thr, pc, (uptr)arg);
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AtExitCtx *ctx = (AtExitCtx*)arg;
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Acquire(thr, ctx->pc, (uptr)arg);
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FuncEntry(thr, ctx->pc);
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((void(*)(int status, void *arg))ctx->f)(status, ctx->arg);
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FuncExit(thr);
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Free(ctx);
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}
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@ -461,11 +474,12 @@ TSAN_INTERCEPTOR(int, on_exit, void(*f)(int, void*), void *arg) {
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auto *ctx = New<AtExitCtx>();
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ctx->f = (void(*)())f;
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ctx->arg = arg;
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ctx->pc = GET_CALLER_PC();
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Release(thr, pc, (uptr)ctx);
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// Memory allocation in __cxa_atexit will race with free during exit,
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// because we do not see synchronization around atexit callback list.
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ThreadIgnoreBegin(thr, pc);
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int res = REAL(on_exit)(on_exit_wrapper, ctx);
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int res = REAL(on_exit)(on_exit_callback_installed_at, ctx);
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ThreadIgnoreEnd(thr);
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return res;
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}
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@ -31,4 +31,5 @@ int main() {
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// CHECK: #0 thread
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// CHECK: Previous write of size 4
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// CHECK: #0 race
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// CHECK: #1 at_exit_wrapper
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// CHECK: #1 at_exit_callback_installed_at
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// CHECK: #2 X
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@ -23,4 +23,5 @@ int main() {
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// CHECK: Write of size 8
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// The exact spelling and number of std frames is hard to guess.
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// CHECK: unique_ptr
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// CHECK: #{{1|2}} cxa_at_exit_wrapper
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// CHECK: #{{1|2}} cxa_at_exit_callback_installed_at
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// CHECK: #{{2|3}} __cxx_global_var_init
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@ -28,4 +28,5 @@ int main() {
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// CHECK: WARNING: ThreadSanitizer: data race
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// CHECK: Write of size 8
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// CHECK: #0 on_exit_callback
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// CHECK: #1 on_exit_wrapper
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// CHECK: #1 on_exit_callback_installed_at
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// CHECK: #2 main
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