[compiler-rt] r271568 - tsan: clean up dynamic TLS memory between reuse
Dmitry Vyukov via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 2 12:18:22 PDT 2016
Author: dvyukov
Date: Thu Jun 2 14:18:22 2016
New Revision: 271568
URL: http://llvm.org/viewvc/llvm-project?rev=271568&view=rev
Log:
tsan: clean up dynamic TLS memory between reuse
Currently the added test produces false race reports with glibc 2.19,
because DLTS memory is reused by pthread under the hood.
Use the DTLS machinery to intercept new DTLS ranges.
__tls_get_addr known to cause issues for tsan in the past,
so write the interceptor more carefully.
Reviewed in http://reviews.llvm.org/D20927
Added:
compiler-rt/trunk/test/tsan/dtls.c
Modified:
compiler-rt/trunk/lib/tsan/rtl/tsan_flags.cc
compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_flags.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_flags.cc?rev=271568&r1=271567&r2=271568&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_flags.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_flags.cc Thu Jun 2 14:18:22 2016
@@ -71,6 +71,7 @@ void InitializeFlags(Flags *f, const cha
cf.print_suppressions = false;
cf.stack_trace_format = " #%n %f %S %M";
cf.exitcode = 66;
+ cf.intercept_tls_get_addr = true;
OverrideCommonFlags(cf);
}
Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc?rev=271568&r1=271567&r2=271568&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc Thu Jun 2 14:18:22 2016
@@ -19,6 +19,7 @@
#include "sanitizer_common/sanitizer_platform_limits_posix.h"
#include "sanitizer_common/sanitizer_placement_new.h"
#include "sanitizer_common/sanitizer_stacktrace.h"
+#include "sanitizer_common/sanitizer_tls_get_addr.h"
#include "interception/interception.h"
#include "tsan_interceptors.h"
#include "tsan_interface.h"
@@ -853,6 +854,7 @@ void DestroyThreadState() {
thr->signal_ctx = 0;
UnmapOrDie(sctx, sizeof(*sctx));
}
+ DTLS_Destroy();
cur_thread_finalize();
}
} // namespace __tsan
@@ -2183,17 +2185,7 @@ static void HandleRecvmsg(ThreadState *t
#undef SANITIZER_INTERCEPT_FGETPWENT
#undef SANITIZER_INTERCEPT_GETPWNAM_AND_FRIENDS
#undef SANITIZER_INTERCEPT_GETPWNAM_R_AND_FRIENDS
-// __tls_get_addr can be called with mis-aligned stack due to:
-// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
-// There are two potential issues:
-// 1. Sanitizer code contains a MOVDQA spill (it does not seem to be the case
-// right now). or 2. ProcessPendingSignal calls user handler which contains
-// MOVDQA spill (this happens right now).
-// Since the interceptor only initializes memory for msan, the simplest solution
-// is to disable the interceptor in tsan (other sanitizers do not call
-// signal handlers from COMMON_INTERCEPTOR_ENTER).
-// As __tls_get_addr has been intercepted in the past, to avoid breaking
-// libtsan ABI, keep it around, but just call the real function.
+// We define our own.
#if SANITIZER_INTERCEPT_TLS_GET_ADDR
#define NEED_TLS_GET_ADDR
#endif
@@ -2429,8 +2421,27 @@ static void syscall_post_fork(uptr pc, i
#include "sanitizer_common/sanitizer_common_syscalls.inc"
#ifdef NEED_TLS_GET_ADDR
+// Define own interceptor instead of sanitizer_common's for three reasons:
+// 1. It must not process pending signals.
+// Signal handlers may contain MOVDQA instruction (see below).
+// 2. It must be as simple as possible to not contain MOVDQA.
+// 3. Sanitizer_common version uses COMMON_INTERCEPTOR_INITIALIZE_RANGE which
+// is empty for tsan (meant only for msan).
+// Note: __tls_get_addr can be called with mis-aligned stack due to:
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
+// So the interceptor must work with mis-aligned stack, in particular, does not
+// execute MOVDQA with stack addresses.
TSAN_INTERCEPTOR(void *, __tls_get_addr, void *arg) {
- return REAL(__tls_get_addr)(arg);
+ void *res = REAL(__tls_get_addr)(arg);
+ ThreadState *thr = cur_thread();
+ if (!thr)
+ return res;
+ DTLS::DTV *dtv = DTLS_on_tls_get_addr(arg, res, thr->tls_addr, thr->tls_size);
+ if (!dtv)
+ return res;
+ // New DTLS block has been allocated.
+ MemoryResetRange(thr, 0, dtv->beg, dtv->size);
+ return res;
}
#endif
Added: compiler-rt/trunk/test/tsan/dtls.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/tsan/dtls.c?rev=271568&view=auto
==============================================================================
--- compiler-rt/trunk/test/tsan/dtls.c (added)
+++ compiler-rt/trunk/test/tsan/dtls.c Thu Jun 2 14:18:22 2016
@@ -0,0 +1,62 @@
+// RUN: %clang_tsan %s -o %t
+// RUN: %clang_tsan %s -DBUILD_SO -fPIC -o %t-so.so -shared
+// RUN: %run %t 2>&1 | FileCheck %s
+
+// Test that tsan cleans up dynamic TLS memory between reuse.
+
+#include "test.h"
+
+#ifndef BUILD_SO
+#include <assert.h>
+#include <dlfcn.h>
+
+typedef volatile long *(* get_t)();
+get_t GetTls;
+
+void *Thread1(void *arg) {
+ pthread_detach(pthread_self());
+ volatile long *x = GetTls();
+ *x = 42;
+ fprintf(stderr, "stack: %p dtls: %p\n", &x, x);
+ barrier_wait(&barrier);
+ return 0;
+}
+
+void *Thread2(void *arg) {
+ volatile long *x = GetTls();
+ *x = 42;
+ fprintf(stderr, "stack: %p dtls: %p\n", &x, x);
+ return 0;
+}
+
+int main(int argc, char *argv[]) {
+ char path[4096];
+ snprintf(path, sizeof(path), "%s-so.so", argv[0]);
+
+ void *handle = dlopen(path, RTLD_LAZY);
+ if (!handle) fprintf(stderr, "%s\n", dlerror());
+ assert(handle != 0);
+ GetTls = (get_t)dlsym(handle, "GetTls");
+ assert(dlerror() == 0);
+
+ barrier_init(&barrier, 2);
+ pthread_t t[2];
+ pthread_create(&t[0], 0, Thread1, 0);
+ barrier_wait(&barrier);
+ // Wait for actual thread termination without using pthread_join,
+ // which would synchronize threads.
+ sleep(1);
+ pthread_create(&t[1], 0, Thread2, 0);
+ pthread_join(t[1], 0);
+ fprintf(stderr, "DONE\n");
+ return 0;
+}
+#else // BUILD_SO
+__thread long huge_thread_local_array[1 << 17];
+long *GetTls() {
+ return &huge_thread_local_array[0];
+}
+#endif
+
+// CHECK-NOT: ThreadSanitizer: data race
+// CHECK: DONE
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