[compiler-rt] r287632 - tsan: switch libignore from /proc/self/maps to dl_iterate_phdr
Diana Picus via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 22 03:13:53 PST 2016
Hi Dmitry,
Can you please have a look at this failure:
http://lab.llvm.org:8011/builders/clang-cmake-aarch64-42vma/builds/1198
?
Thanks,
Diana
On 22 November 2016 at 11:49, Dmitry Vyukov via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: dvyukov
> Date: Tue Nov 22 03:49:11 2016
> New Revision: 287632
>
> URL: http://llvm.org/viewvc/llvm-project?rev=287632&view=rev
> Log:
> tsan: switch libignore from /proc/self/maps to dl_iterate_phdr
>
> /proc/self/maps can't be read atomically, this leads to episodic
> crashes in libignore as it thinks that a module is loaded twice.
> See the new test for an example.
> dl_iterate_phdr does not have this problem.
> Switch libignore to dl_iterate_phdr.
>
>
> Added:
> compiler-rt/trunk/test/tsan/ignore_lib5.cc
> compiler-rt/trunk/test/tsan/ignore_lib5.cc.supp
> Modified:
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_libignore.cc
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_libignore.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_libignore.cc?rev=287632&r1=287631&r2=287632&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_libignore.cc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_libignore.cc Tue Nov 22 03:49:11 2016
> @@ -50,23 +50,23 @@ void LibIgnore::OnLibraryLoaded(const ch
> }
>
> // Scan suppressions list and find newly loaded and unloaded libraries.
> - MemoryMappingLayout proc_maps(/*cache_enabled*/false);
> - InternalScopedString module(kMaxPathLength);
> + ListOfModules modules;
> + modules.init();
> for (uptr i = 0; i < count_; i++) {
> Lib *lib = &libs_[i];
> bool loaded = false;
> - proc_maps.Reset();
> - uptr b, e, off, prot;
> - while (proc_maps.Next(&b, &e, &off, module.data(), module.size(), &prot)) {
> - if ((prot & MemoryMappingLayout::kProtectionExecute) == 0)
> - continue;
> - if (TemplateMatch(lib->templ, module.data()) ||
> - (lib->real_name &&
> - internal_strcmp(lib->real_name, module.data()) == 0)) {
> + for (const auto &mod : modules) {
> + for (const auto &range : mod.ranges()) {
> + if (!range.executable)
> + continue;
> + if (!TemplateMatch(lib->templ, mod.full_name()) &&
> + !(lib->real_name &&
> + internal_strcmp(lib->real_name, mod.full_name()) == 0))
> + continue;
> if (loaded) {
> Report("%s: called_from_lib suppression '%s' is matched against"
> " 2 libraries: '%s' and '%s'\n",
> - SanitizerToolName, lib->templ, lib->name, module.data());
> + SanitizerToolName, lib->templ, lib->name, mod.full_name());
> Die();
> }
> loaded = true;
> @@ -75,13 +75,14 @@ void LibIgnore::OnLibraryLoaded(const ch
> VReport(1,
> "Matched called_from_lib suppression '%s' against library"
> " '%s'\n",
> - lib->templ, module.data());
> + lib->templ, mod.full_name());
> lib->loaded = true;
> - lib->name = internal_strdup(module.data());
> + lib->name = internal_strdup(mod.full_name());
> const uptr idx = atomic_load(&loaded_count_, memory_order_relaxed);
> - code_ranges_[idx].begin = b;
> - code_ranges_[idx].end = e;
> + code_ranges_[idx].begin = range.beg;
> + code_ranges_[idx].end = range.end;
> atomic_store(&loaded_count_, idx + 1, memory_order_release);
> + break;
> }
> }
> if (lib->loaded && !loaded) {
>
> Added: compiler-rt/trunk/test/tsan/ignore_lib5.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/tsan/ignore_lib5.cc?rev=287632&view=auto
> ==============================================================================
> --- compiler-rt/trunk/test/tsan/ignore_lib5.cc (added)
> +++ compiler-rt/trunk/test/tsan/ignore_lib5.cc Tue Nov 22 03:49:11 2016
> @@ -0,0 +1,65 @@
> +// RUN: %clangxx_tsan -O1 %s -DLIB -fPIC -fno-sanitize=thread -shared -o %T/libignore_lib1.so
> +// RUN: %clangxx_tsan -O1 %s -o %t
> +// RUN: echo running w/o suppressions:
> +// RUN: %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOSUPP
> +// RUN: echo running with suppressions:
> +// RUN: %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
> +
> +// REQUIRES: stable-runtime
> +
> +// Previously the test episodically failed with:
> +// ThreadSanitizer: called_from_lib suppression '/libignore_lib1.so$' is
> +// matched against 2 libraries: '/libignore_lib1.so' and '/libignore_lib1.so'
> +// This was caused by non-atomicity of reading of /proc/self/maps.
> +
> +#ifndef LIB
> +
> +#include <dlfcn.h>
> +#include <sys/mman.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <errno.h>
> +#include <libgen.h>
> +#include <string>
> +#include "test.h"
> +
> +void *thr(void *arg) {
> + // This thread creates lots of separate mappings in /proc/self/maps before
> + // the ignored library.
> + for (int i = 0; i < 10000; i++) {
> + if (i == 5000)
> + barrier_wait(&barrier);
> + mmap(0, 4096, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1 , 0);
> + mmap(0, 4096, PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1 , 0);
> + }
> + return 0;
> +}
> +
> +int main(int argc, char **argv) {
> + barrier_init(&barrier, 2);
> + pthread_t th;
> + pthread_create(&th, 0, thr, 0);
> + barrier_wait(&barrier);
> + std::string lib = std::string(dirname(argv[0])) + "/libignore_lib1.so";
> + void *h = dlopen(lib.c_str(), RTLD_GLOBAL | RTLD_NOW);
> + if (h == 0)
> + exit(printf("failed to load the library (%d)\n", errno));
> + void (*f)() = (void(*)())dlsym(h, "libfunc");
> + if (f == 0)
> + exit(printf("failed to find the func (%d)\n", errno));
> + pthread_join(th, 0);
> + f();
> +}
> +
> +#else // #ifdef LIB
> +
> +#include "ignore_lib_lib.h"
> +
> +#endif // #ifdef LIB
> +
> +// CHECK-NOSUPP: WARNING: ThreadSanitizer: data race
> +// CHECK-NOSUPP: OK
> +
> +// CHECK-WITHSUPP-NOT: WARNING: ThreadSanitizer: data race
> +// CHECK-WITHSUPP: OK
> +
>
> Added: compiler-rt/trunk/test/tsan/ignore_lib5.cc.supp
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/tsan/ignore_lib5.cc.supp?rev=287632&view=auto
> ==============================================================================
> --- compiler-rt/trunk/test/tsan/ignore_lib5.cc.supp (added)
> +++ compiler-rt/trunk/test/tsan/ignore_lib5.cc.supp Tue Nov 22 03:49:11 2016
> @@ -0,0 +1,2 @@
> +called_from_lib:/libignore_lib1.so$
> +
>
>
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