// Copyright 2018 The Abseil Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include "absl/debugging/symbolize.h" #ifndef _WIN32 #include #include #endif #include #include #include #include "gmock/gmock.h" #include "gtest/gtest.h" #include "absl/base/attributes.h" #include "absl/base/casts.h" #include "absl/base/config.h" #include "absl/base/internal/per_thread_tls.h" #include "absl/base/internal/raw_logging.h" #include "absl/base/optimization.h" #include "absl/debugging/internal/stack_consumption.h" #include "absl/memory/memory.h" #include "absl/strings/string_view.h" using testing::Contains; #ifdef _WIN32 #define ABSL_SYMBOLIZE_TEST_NOINLINE __declspec(noinline) #else #define ABSL_SYMBOLIZE_TEST_NOINLINE ABSL_ATTRIBUTE_NOINLINE #endif // Functions to symbolize. Use C linkage to avoid mangled names. extern "C" { ABSL_SYMBOLIZE_TEST_NOINLINE void nonstatic_func() { // The next line makes this a unique function to prevent the compiler from // folding identical functions together. volatile int x = __LINE__; static_cast(x); ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); } ABSL_SYMBOLIZE_TEST_NOINLINE static void static_func() { // The next line makes this a unique function to prevent the compiler from // folding identical functions together. volatile int x = __LINE__; static_cast(x); ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); } } // extern "C" struct Foo { static void func(int x); }; // A C++ method that should have a mangled name. ABSL_SYMBOLIZE_TEST_NOINLINE void Foo::func(int) { // The next line makes this a unique function to prevent the compiler from // folding identical functions together. volatile int x = __LINE__; static_cast(x); ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); } // Create functions that will remain in different text sections in the // final binary when linker option "-z,keep-text-section-prefix" is used. int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.unlikely) unlikely_func() { return 0; } int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.hot) hot_func() { return 0; } int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.startup) startup_func() { return 0; } int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.exit) exit_func() { return 0; } int /*ABSL_ATTRIBUTE_SECTION_VARIABLE(.text)*/ regular_func() { return 0; } // Thread-local data may confuse the symbolizer, ensure that it does not. // Variable sizes and order are important. #if ABSL_PER_THREAD_TLS static ABSL_PER_THREAD_TLS_KEYWORD char symbolize_test_thread_small[1]; static ABSL_PER_THREAD_TLS_KEYWORD char symbolize_test_thread_big[2 * 1024 * 1024]; #endif #if !defined(__EMSCRIPTEN__) // Used below to hopefully inhibit some compiler/linker optimizations // that may remove kHpageTextPadding, kPadding0, and kPadding1 from // the binary. static volatile bool volatile_bool = false; // Force the binary to be large enough that a THP .text remap will succeed. static constexpr size_t kHpageSize = 1 << 21; const char kHpageTextPadding[kHpageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE( .text) = ""; #endif // !defined(__EMSCRIPTEN__) static char try_symbolize_buffer[4096]; // A wrapper function for absl::Symbolize() to make the unit test simple. The // limit must be < sizeof(try_symbolize_buffer). Returns null if // absl::Symbolize() returns false, otherwise returns try_symbolize_buffer with // the result of absl::Symbolize(). static const char *TrySymbolizeWithLimit(void *pc, int limit) { ABSL_RAW_CHECK(limit <= sizeof(try_symbolize_buffer), "try_symbolize_buffer is too small"); // Use the heap to facilitate heap and buffer sanitizer tools. auto heap_buffer = absl::make_unique(sizeof(try_symbolize_buffer)); bool found = absl::Symbolize(pc, heap_buffer.get(), limit); if (found) { ABSL_RAW_CHECK(strnlen(heap_buffer.get(), limit) < limit, "absl::Symbolize() did not properly terminate the string"); strncpy(try_symbolize_buffer, heap_buffer.get(), sizeof(try_symbolize_buffer) - 1); try_symbolize_buffer[sizeof(try_symbolize_buffer) - 1] = '\0'; } return found ? try_symbolize_buffer : nullptr; } // A wrapper for TrySymbolizeWithLimit(), with a large limit. static const char *TrySymbolize(void *pc) { return TrySymbolizeWithLimit(pc, sizeof(try_symbolize_buffer)); } #if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE) || \ defined(ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE) || \ defined(ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE) // Test with a return address. void ABSL_ATTRIBUTE_NOINLINE TestWithReturnAddress() { #if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE) void *return_address = __builtin_return_address(0); const char *symbol = TrySymbolize(return_address); ABSL_RAW_CHECK(symbol != nullptr, "TestWithReturnAddress failed"); ABSL_RAW_CHECK(strcmp(symbol, "main") == 0, "TestWithReturnAddress failed"); std::cout << "TestWithReturnAddress passed" << std::endl; #endif } #ifndef ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE TEST(Symbolize, Cached) { // Compilers should give us pointers to them. EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func))); // The name of an internal linkage symbol is not specified; allow either a // mangled or an unmangled name here. const char *static_func_symbol = TrySymbolize((void *)(&static_func)); EXPECT_TRUE(strcmp("static_func", static_func_symbol) == 0 || strcmp("static_func()", static_func_symbol) == 0); EXPECT_TRUE(nullptr == TrySymbolize(nullptr)); } TEST(Symbolize, Truncation) { constexpr char kNonStaticFunc[] = "nonstatic_func"; EXPECT_STREQ("nonstatic_func", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) + 1)); EXPECT_STREQ("nonstatic_...", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) + 0)); EXPECT_STREQ("nonstatic...", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) - 1)); EXPECT_STREQ("n...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 5)); EXPECT_STREQ("...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 4)); EXPECT_STREQ("..", TrySymbolizeWithLimit((void *)(&nonstatic_func), 3)); EXPECT_STREQ(".", TrySymbolizeWithLimit((void *)(&nonstatic_func), 2)); EXPECT_STREQ("", TrySymbolizeWithLimit((void *)(&nonstatic_func), 1)); EXPECT_EQ(nullptr, TrySymbolizeWithLimit((void *)(&nonstatic_func), 0)); } TEST(Symbolize, SymbolizeWithDemangling) { Foo::func(100); EXPECT_STREQ("Foo::func()", TrySymbolize((void *)(&Foo::func))); } TEST(Symbolize, SymbolizeSplitTextSections) { EXPECT_STREQ("unlikely_func()", TrySymbolize((void *)(&unlikely_func))); EXPECT_STREQ("hot_func()", TrySymbolize((void *)(&hot_func))); EXPECT_STREQ("startup_func()", TrySymbolize((void *)(&startup_func))); EXPECT_STREQ("exit_func()", TrySymbolize((void *)(&exit_func))); EXPECT_STREQ("regular_func()", TrySymbolize((void *)(®ular_func))); } // Tests that verify that Symbolize stack footprint is within some limit. #ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION static void *g_pc_to_symbolize; static char g_symbolize_buffer[4096]; static char *g_symbolize_result; static void SymbolizeSignalHandler(int signo) { if (absl::Symbolize(g_pc_to_symbolize, g_symbolize_buffer, sizeof(g_symbolize_buffer))) { g_symbolize_result = g_symbolize_buffer; } else { g_symbolize_result = nullptr; } } // Call Symbolize and figure out the stack footprint of this call. static const char *SymbolizeStackConsumption(void *pc, int *stack_consumed) { g_pc_to_symbolize = pc; *stack_consumed = absl::debugging_internal::GetSignalHandlerStackConsumption( SymbolizeSignalHandler); return g_symbolize_result; } static int GetStackConsumptionUpperLimit() { // Symbolize stack consumption should be within 2kB. int stack_consumption_upper_limit = 2048; #if defined(ABSL_HAVE_ADDRESS_SANITIZER) || \ defined(ABSL_HAVE_MEMORY_SANITIZER) || defined(ABSL_HAVE_THREAD_SANITIZER) // Account for sanitizer instrumentation requiring additional stack space. stack_consumption_upper_limit *= 5; #endif return stack_consumption_upper_limit; } TEST(Symbolize, SymbolizeStackConsumption) { int stack_consumed = 0; const char *symbol = SymbolizeStackConsumption((void *)(&nonstatic_func), &stack_consumed); EXPECT_STREQ("nonstatic_func", symbol); EXPECT_GT(stack_consumed, 0); EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit()); // The name of an internal linkage symbol is not specified; allow either a // mangled or an unmangled name here. symbol = SymbolizeStackConsumption((void *)(&static_func), &stack_consumed); EXPECT_TRUE(strcmp("static_func", symbol) == 0 || strcmp("static_func()", symbol) == 0); EXPECT_GT(stack_consumed, 0); EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit()); } TEST(Symbolize, SymbolizeWithDemanglingStackConsumption) { Foo::func(100); int stack_consumed = 0; const char *symbol = SymbolizeStackConsumption((void *)(&Foo::func), &stack_consumed); EXPECT_STREQ("Foo::func()", symbol); EXPECT_GT(stack_consumed, 0); EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit()); } #endif // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION #ifndef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE // Use a 64K page size for PPC. const size_t kPageSize = 64 << 10; // We place a read-only symbols into the .text section and verify that we can // symbolize them and other symbols after remapping them. const char kPadding0[kPageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(.text) = ""; const char kPadding1[kPageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(.text) = ""; static int FilterElfHeader(struct dl_phdr_info *info, size_t size, void *data) { for (int i = 0; i < info->dlpi_phnum; i++) { if (info->dlpi_phdr[i].p_type == PT_LOAD && info->dlpi_phdr[i].p_flags == (PF_R | PF_X)) { const void *const vaddr = absl::bit_cast(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr); const auto segsize = info->dlpi_phdr[i].p_memsz; const char *self_exe; if (info->dlpi_name != nullptr && info->dlpi_name[0] != '\0') { self_exe = info->dlpi_name; } else { self_exe = "/proc/self/exe"; } absl::debugging_internal::RegisterFileMappingHint( vaddr, reinterpret_cast(vaddr) + segsize, info->dlpi_phdr[i].p_offset, self_exe); return 1; } } return 1; } TEST(Symbolize, SymbolizeWithMultipleMaps) { // Force kPadding0 and kPadding1 to be linked in. if (volatile_bool) { ABSL_RAW_LOG(INFO, "%s", kPadding0); ABSL_RAW_LOG(INFO, "%s", kPadding1); } // Verify we can symbolize everything. char buf[512]; memset(buf, 0, sizeof(buf)); absl::Symbolize(kPadding0, buf, sizeof(buf)); EXPECT_STREQ("kPadding0", buf); memset(buf, 0, sizeof(buf)); absl::Symbolize(kPadding1, buf, sizeof(buf)); EXPECT_STREQ("kPadding1", buf); // Specify a hint for the executable segment. dl_iterate_phdr(FilterElfHeader, nullptr); // Reload at least one page out of kPadding0, kPadding1 const char *ptrs[] = {kPadding0, kPadding1}; for (const char *ptr : ptrs) { const int kMapFlags = MAP_ANONYMOUS | MAP_PRIVATE; void *addr = mmap(nullptr, kPageSize, PROT_READ, kMapFlags, 0, 0); ASSERT_NE(addr, MAP_FAILED); // kPadding[0-1] is full of zeroes, so we can remap anywhere within it, but // we ensure there is at least a full page of padding. void *remapped = reinterpret_cast( reinterpret_cast(ptr + kPageSize) & ~(kPageSize - 1ULL)); const int kMremapFlags = (MREMAP_MAYMOVE | MREMAP_FIXED); void *ret = mremap(addr, kPageSize, kPageSize, kMremapFlags, remapped); ASSERT_NE(ret, MAP_FAILED); } // Invalidate the symbolization cache so we are forced to rely on the hint. absl::Symbolize(nullptr, buf, sizeof(buf)); // Verify we can still symbolize. const char *expected[] = {"kPadding0", "kPadding1"}; const size_t offsets[] = {0, kPageSize, 2 * kPageSize, 3 * kPageSize}; for (int i = 0; i < 2; i++) { for (size_t offset : offsets) { memset(buf, 0, sizeof(buf)); absl::Symbolize(ptrs[i] + offset, buf, sizeof(buf)); EXPECT_STREQ(expected[i], buf); } } } // Appends string(*args->arg) to args->symbol_buf. static void DummySymbolDecorator( const absl::debugging_internal::SymbolDecoratorArgs *args) { std::string *message = static_cast(args->arg); strncat(args->symbol_buf, message->c_str(), args->symbol_buf_size - strlen(args->symbol_buf) - 1); } TEST(Symbolize, InstallAndRemoveSymbolDecorators) { int ticket_a; std::string a_message("a"); EXPECT_GE(ticket_a = absl::debugging_internal::InstallSymbolDecorator( DummySymbolDecorator, &a_message), 0); int ticket_b; std::string b_message("b"); EXPECT_GE(ticket_b = absl::debugging_internal::InstallSymbolDecorator( DummySymbolDecorator, &b_message), 0); int ticket_c; std::string c_message("c"); EXPECT_GE(ticket_c = absl::debugging_internal::InstallSymbolDecorator( DummySymbolDecorator, &c_message), 0); // Use addresses 4 and 8 here to ensure that we always use valid addresses // even on systems that require instructions to be 32-bit aligned. char *address = reinterpret_cast(4); EXPECT_STREQ("abc", TrySymbolize(address)); EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_b)); EXPECT_STREQ("ac", TrySymbolize(address + 4)); // Cleanup: remove all remaining decorators so other stack traces don't // get mystery "ac" decoration. EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_a)); EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_c)); } // Some versions of Clang with optimizations enabled seem to be able // to optimize away the .data section if no variables live in the // section. This variable should get placed in the .data section, and // the test below checks for the existence of a .data section. static int in_data_section = 1; TEST(Symbolize, ForEachSection) { int fd = TEMP_FAILURE_RETRY(open("/proc/self/exe", O_RDONLY)); ASSERT_NE(fd, -1); std::vector sections; ASSERT_TRUE(absl::debugging_internal::ForEachSection( fd, [§ions](const absl::string_view name, const ElfW(Shdr) &) { sections.emplace_back(name); return true; })); // Check for the presence of common section names. EXPECT_THAT(sections, Contains(".text")); EXPECT_THAT(sections, Contains(".rodata")); EXPECT_THAT(sections, Contains(".bss")); ++in_data_section; EXPECT_THAT(sections, Contains(".data")); close(fd); } #endif // !ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE #endif // !ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE // x86 specific tests. Uses some inline assembler. extern "C" { inline void *ABSL_ATTRIBUTE_ALWAYS_INLINE inline_func() { void *pc = nullptr; #if defined(__i386__) __asm__ __volatile__("call 1f;\n 1: pop %[PC]" : [ PC ] "=r"(pc)); #elif defined(__x86_64__) __asm__ __volatile__("leaq 0(%%rip),%[PC];\n" : [ PC ] "=r"(pc)); #endif return pc; } void *ABSL_ATTRIBUTE_NOINLINE non_inline_func() { void *pc = nullptr; #if defined(__i386__) __asm__ __volatile__("call 1f;\n 1: pop %[PC]" : [ PC ] "=r"(pc)); #elif defined(__x86_64__) __asm__ __volatile__("leaq 0(%%rip),%[PC];\n" : [ PC ] "=r"(pc)); #endif return pc; } void ABSL_ATTRIBUTE_NOINLINE TestWithPCInsideNonInlineFunction() { #if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE) && \ (defined(__i386__) || defined(__x86_64__)) void *pc = non_inline_func(); const char *symbol = TrySymbolize(pc); ABSL_RAW_CHECK(symbol != nullptr, "TestWithPCInsideNonInlineFunction failed"); ABSL_RAW_CHECK(strcmp(symbol, "non_inline_func") == 0, "TestWithPCInsideNonInlineFunction failed"); std::cout << "TestWithPCInsideNonInlineFunction passed" << std::endl; #endif } void ABSL_ATTRIBUTE_NOINLINE TestWithPCInsideInlineFunction() { #if defined(ABSL_HAVE_ATTRIBUTE_ALWAYS_INLINE) && \ (defined(__i386__) || defined(__x86_64__)) void *pc = inline_func(); // Must be inlined. const char *symbol = TrySymbolize(pc); ABSL_RAW_CHECK(symbol != nullptr, "TestWithPCInsideInlineFunction failed"); ABSL_RAW_CHECK(strcmp(symbol, __FUNCTION__) == 0, "TestWithPCInsideInlineFunction failed"); std::cout << "TestWithPCInsideInlineFunction passed" << std::endl; #endif } } #if defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target) // Test that we correctly identify bounds of Thumb functions on ARM. // // Thumb functions have the lowest-order bit set in their addresses in the ELF // symbol table. This requires some extra logic to properly compute function // bounds. To test this logic, nudge a Thumb function right up against an ARM // function and try to symbolize the ARM function. // // A naive implementation will simply use the Thumb function's entry point as // written in the symbol table and will therefore treat the Thumb function as // extending one byte further in the instruction stream than it actually does. // When asked to symbolize the start of the ARM function, it will identify an // overlap between the Thumb and ARM functions, and it will return the name of // the Thumb function. // // A correct implementation, on the other hand, will null out the lowest-order // bit in the Thumb function's entry point. It will correctly compute the end of // the Thumb function, it will find no overlap between the Thumb and ARM // functions, and it will return the name of the ARM function. __attribute__((target("thumb"))) int ArmThumbOverlapThumb(int x) { return x * x * x; } __attribute__((target("arm"))) int ArmThumbOverlapArm(int x) { return x * x * x; } void ABSL_ATTRIBUTE_NOINLINE TestArmThumbOverlap() { #if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE) const char *symbol = TrySymbolize((void *)&ArmThumbOverlapArm); ABSL_RAW_CHECK(symbol != nullptr, "TestArmThumbOverlap failed"); ABSL_RAW_CHECK(strcmp("ArmThumbOverlapArm()", symbol) == 0, "TestArmThumbOverlap failed"); std::cout << "TestArmThumbOverlap passed" << std::endl; #endif } #endif // defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target) #elif defined(_WIN32) #if !defined(ABSL_CONSUME_DLL) TEST(Symbolize, Basics) { EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func))); // The name of an internal linkage symbol is not specified; allow either a // mangled or an unmangled name here. const char *static_func_symbol = TrySymbolize((void *)(&static_func)); ASSERT_TRUE(static_func_symbol != nullptr); EXPECT_TRUE(strstr(static_func_symbol, "static_func") != nullptr); EXPECT_TRUE(nullptr == TrySymbolize(nullptr)); } TEST(Symbolize, Truncation) { constexpr char kNonStaticFunc[] = "nonstatic_func"; EXPECT_STREQ("nonstatic_func", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) + 1)); EXPECT_STREQ("nonstatic_...", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) + 0)); EXPECT_STREQ("nonstatic...", TrySymbolizeWithLimit((void *)(&nonstatic_func), strlen(kNonStaticFunc) - 1)); EXPECT_STREQ("n...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 5)); EXPECT_STREQ("...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 4)); EXPECT_STREQ("..", TrySymbolizeWithLimit((void *)(&nonstatic_func), 3)); EXPECT_STREQ(".", TrySymbolizeWithLimit((void *)(&nonstatic_func), 2)); EXPECT_STREQ("", TrySymbolizeWithLimit((void *)(&nonstatic_func), 1)); EXPECT_EQ(nullptr, TrySymbolizeWithLimit((void *)(&nonstatic_func), 0)); } TEST(Symbolize, SymbolizeWithDemangling) { const char *result = TrySymbolize((void *)(&Foo::func)); ASSERT_TRUE(result != nullptr); EXPECT_TRUE(strstr(result, "Foo::func") != nullptr) << result; } #endif // !defined(ABSL_CONSUME_DLL) #else // Symbolizer unimplemented TEST(Symbolize, Unimplemented) { char buf[64]; EXPECT_FALSE(absl::Symbolize((void *)(&nonstatic_func), buf, sizeof(buf))); EXPECT_FALSE(absl::Symbolize((void *)(&static_func), buf, sizeof(buf))); EXPECT_FALSE(absl::Symbolize((void *)(&Foo::func), buf, sizeof(buf))); } #endif int main(int argc, char **argv) { #if !defined(__EMSCRIPTEN__) // Make sure kHpageTextPadding is linked into the binary. if (volatile_bool) { ABSL_RAW_LOG(INFO, "%s", kHpageTextPadding); } #endif // !defined(__EMSCRIPTEN__) #if ABSL_PER_THREAD_TLS // Touch the per-thread variables. symbolize_test_thread_small[0] = 0; symbolize_test_thread_big[0] = 0; #endif absl::InitializeSymbolizer(argv[0]); testing::InitGoogleTest(&argc, argv); #if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE) || \ defined(ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE) TestWithPCInsideInlineFunction(); TestWithPCInsideNonInlineFunction(); TestWithReturnAddress(); #if defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target) TestArmThumbOverlap(); #endif #endif return RUN_ALL_TESTS(); }