[compiler-rt] r287632 - tsan: switch libignore from /proc/self/maps to dl_iterate_phdr
Dmitry Vyukov via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 22 03:17:49 PST 2016
Looking
Thanks
On Tue, Nov 22, 2016 at 12:13 PM, Diana Picus <diana.picus at linaro.org> wrote:
> 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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