[compiler-rt] r179032 - [libsymbolized] If we can't find an address in the list of shared libraries, try to reload it.
Alexander Potapenko
glider at google.com
Mon Apr 8 11:29:30 PDT 2013
Good idea. I'll do that tomorrow.
On Apr 8, 2013 10:09 PM, "Alexey Samsonov" <samsonov at google.com> wrote:
>
>
>
> On Mon, Apr 8, 2013 at 9:46 PM, Alexander Potapenko <glider at google.com>wrote:
>
>> Author: glider
>> Date: Mon Apr 8 12:46:34 2013
>> New Revision: 179032
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=179032&view=rev
>> Log:
>> [libsymbolized] If we can't find an address in the list of shared
>> libraries, try to reload it.
>>
>> Add a regression test for the case where such behavior helps TSan:
>> 1. race is reported in the main module
>> 2. new shared library is loaded
>> 3. race is reported in the shared library
>>
>>
>> Added:
>> compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/
>> compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/lit.local.cfg
>> compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/load_shared_lib-so.cc
>> compiler-rt/trunk/lib/tsan/lit_tests/load_shared_lib.cc
>> Modified:
>> compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer.cc
>>
>> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer.cc?rev=179032&r1=179031&r2=179032&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer.cc
>> (original)
>> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer.cc Mon
>> Apr 8 12:46:34 2013
>> @@ -239,6 +239,7 @@ class InternalSymbolizer {
>>
>> class Symbolizer {
>> public:
>> + Symbolizer() : modules_fresh_(false) { };
>> uptr SymbolizeCode(uptr addr, AddressInfo *frames, uptr max_frames) {
>> if (max_frames == 0)
>> return 0;
>> @@ -376,7 +377,8 @@ class Symbolizer {
>> }
>>
>> LoadedModule *FindModuleForAddress(uptr address) {
>> - if (modules_ == 0) {
>> + bool modules_were_reloaded = false;
>> + if (modules_ == 0 || !modules_fresh_) {
>> modules_ = (LoadedModule*)(symbolizer_allocator.Allocate(
>> kMaxNumberOfModuleContexts * sizeof(LoadedModule)));
>>
>
> Do you allocate new array of modules each time address is not found (and
> leak the previous array)?
> This is dangerous - sizeof(array of modules) is pretty large, and TSan may
> quickly leak memory in this case...
> I think we may switch to InternalVector<> for storing modules here, and
> call .clear() on it to unmap memory.
>
>
>
>> CHECK(modules_);
>> @@ -384,14 +386,25 @@ class Symbolizer {
>> // FIXME: Return this check when GetListOfModules is implemented
>> on Mac.
>> // CHECK_GT(n_modules_, 0);
>> CHECK_LT(n_modules_, kMaxNumberOfModuleContexts);
>> + modules_fresh_ = true;
>> + modules_were_reloaded = true;
>> }
>> for (uptr i = 0; i < n_modules_; i++) {
>> if (modules_[i].containsAddress(address)) {
>> return &modules_[i];
>> }
>> }
>> + // Reload the modules and look up again, if we haven't tried it yet.
>> + if (!modules_were_reloaded) {
>> + // FIXME: set modules_fresh_ from dlopen()/dlclose() interceptors.
>> + // It's too aggressive to reload the list of modules each time we
>> fail
>> + // to find a module for a given address.
>> + modules_fresh_ = false;
>> + return FindModuleForAddress(address);
>> + }
>> return 0;
>> }
>> +
>> void ReportExternalSymbolizerError(const char *msg) {
>> // Don't use atomics here for now, as SymbolizeCode can't be called
>> // from multiple threads anyway.
>> @@ -406,6 +419,8 @@ class Symbolizer {
>> static const uptr kMaxNumberOfModuleContexts = 1 << 14;
>> LoadedModule *modules_; // Array of module descriptions is leaked.
>> uptr n_modules_;
>> + // If stale, need to reload the modules before looking up addresses.
>> + bool modules_fresh_;
>>
>> ExternalSymbolizer *external_symbolizer_; // Leaked.
>> InternalSymbolizer *internal_symbolizer_; // Leaked.
>>
>> Added: compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/lit.local.cfg
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/lit.local.cfg?rev=179032&view=auto
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/lit.local.cfg (added)
>> +++ compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/lit.local.cfg Mon Apr
>> 8 12:46:34 2013
>> @@ -0,0 +1,4 @@
>> +# Sources in this directory are compiled as shared libraries and used by
>> +# tests in parent directory.
>> +
>> +config.suffixes = []
>>
>> Added:
>> compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/load_shared_lib-so.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/load_shared_lib-so.cc?rev=179032&view=auto
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/load_shared_lib-so.cc
>> (added)
>> +++ compiler-rt/trunk/lib/tsan/lit_tests/SharedLibs/load_shared_lib-so.cc
>> Mon Apr 8 12:46:34 2013
>> @@ -0,0 +1,22 @@
>> +//===----------- load_shared_lib-so.cc --------------------------*- C++
>> -*-===//
>> +//
>> +// The LLVM Compiler Infrastructure
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>>
>> +//===----------------------------------------------------------------------===//
>> +//
>> +// This file is a part of ThreadSanitizer (TSan), a race detector.
>> +//
>>
>> +//===----------------------------------------------------------------------===//
>> +
>> +#include <stddef.h>
>> +
>> +int GLOB_SHARED = 0;
>> +
>> +extern "C"
>> +void *write_from_so(void *unused) {
>> + GLOB_SHARED++;
>> + return NULL;
>> +}
>>
>> Added: compiler-rt/trunk/lib/tsan/lit_tests/load_shared_lib.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/lit_tests/load_shared_lib.cc?rev=179032&view=auto
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/tsan/lit_tests/load_shared_lib.cc (added)
>> +++ compiler-rt/trunk/lib/tsan/lit_tests/load_shared_lib.cc Mon Apr 8
>> 12:46:34 2013
>> @@ -0,0 +1,44 @@
>> +// Check that if the list of shared libraries changes between the two
>> race
>> +// reports, the second report occurring in a new shared library is still
>> +// symbolized correctly.
>> +
>> +// RUN: %clangxx_tsan -O1 %p/SharedLibs/load_shared_lib-so.cc \
>> +// RUN: -fPIC -shared -o %t-so.so
>> +// RUN: %clangxx_tsan -O1 %s -o %t && %t 2>&1 | FileCheck %s
>> +
>> +#include <dlfcn.h>
>> +#include <pthread.h>
>> +#include <stdio.h>
>> +
>> +#include <string>
>> +
>> +int GLOB = 0;
>> +
>> +void *write_glob(void *unused) {
>> + GLOB++;
>> + return NULL;
>> +}
>> +
>> +void race_two_threads(void *(*access_callback)(void *)) {
>> + pthread_t t1, t2;
>> + pthread_create(&t1, NULL, access_callback, NULL);
>> + pthread_create(&t2, NULL, access_callback, NULL);
>> + pthread_join(t1, NULL);
>> + pthread_join(t2, NULL);
>> +}
>> +
>> +int main(int argc, char *argv[]) {
>> + std::string path = std::string(argv[0]) + std::string("-so.so");
>> + race_two_threads(write_glob);
>> + // CHECK: write_glob
>> + void *lib = dlopen(path.c_str(), RTLD_NOW);
>> + if (!lib) {
>> + printf("error in dlopen(): %s\n", dlerror());
>> + return 1;
>> + }
>> + void *(*write_from_so)(void *);
>> + *(void **)&write_from_so = dlsym(lib, "write_from_so");
>> + race_two_threads(write_from_so);
>> + // CHECK: write_from_so
>> + return 0;
>> +}
>>
>>
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>>
>
>
>
> --
> Alexey Samsonov, MSK
>
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