// 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 <fcntl.h>
#include <sys/mman.h>
#endif
#include <cstring>
#include <iostream>
#include <memory>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
#include "absl/base/casts.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"
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<void>(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<void>(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<void>(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<char[]>(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));
}
#ifdef ABSL_INTERNAL_HAVE_ELF_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(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
defined(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
// 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<void *>(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<const char *>(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<void *>(
reinterpret_cast<uintptr_t>(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<std::string *>(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);
char *address = reinterpret_cast<char *>(1);
EXPECT_STREQ("abc", TrySymbolize(address++));
EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_b));
EXPECT_STREQ("ac", TrySymbolize(address++));
// 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<std::string> sections;
ASSERT_TRUE(absl::debugging_internal::ForEachSection(
fd, [§ions](const std::string &name, const ElfW(Shdr) &) {
sections.push_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);
}
// 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
}
}
// 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
}
#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);
#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
TestWithPCInsideInlineFunction();
TestWithPCInsideNonInlineFunction();
TestWithReturnAddress();
#endif
return RUN_ALL_TESTS();
}
