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misterg 2017-09-19 16:54:40 -04:00
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170
absl/debugging/BUILD.bazel Normal file
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#
# Copyright 2017 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
#
# http://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.
#
load(
"//absl:copts.bzl",
"ABSL_DEFAULT_COPTS",
)
package(
default_visibility = ["//visibility:public"],
)
licenses(["notice"]) # Apache 2.0
cc_library(
name = "stacktrace",
srcs = [
"stacktrace.cc",
],
hdrs = ["stacktrace.h"],
copts = ABSL_DEFAULT_COPTS,
deps = [
":debugging_internal",
"//absl/base",
"//absl/base:core_headers",
],
)
cc_library(
name = "debugging_internal",
srcs = [
"internal/address_is_readable.cc",
"internal/elf_mem_image.cc",
"internal/vdso_support.cc",
],
hdrs = [
"internal/address_is_readable.h",
"internal/elf_mem_image.h",
"internal/stacktrace_aarch64-inl.inc",
"internal/stacktrace_arm-inl.inc",
"internal/stacktrace_config.h",
"internal/stacktrace_generic-inl.inc",
"internal/stacktrace_libunwind-inl.inc",
"internal/stacktrace_powerpc-inl.inc",
"internal/stacktrace_unimplemented-inl.inc",
"internal/stacktrace_win32-inl.inc",
"internal/stacktrace_x86-inl.inc",
"internal/vdso_support.h",
],
copts = ABSL_DEFAULT_COPTS,
deps = [
"//absl/base",
"//absl/base:dynamic_annotations",
"//absl/base:core_headers",
],
)
cc_library(
name = "leak_check",
srcs = select({
# The leak checking interface depends on weak function
# declarations that may not necessarily have definitions.
# Windows doesn't support this, and ios requires
# guaranteed definitions for weak symbols.
"//absl:ios": [],
"//absl:windows": [],
"//conditions:default": [
"leak_check.cc",
],
}),
hdrs = select({
"//absl:ios": [],
"//absl:windows": [],
"//conditions:default": ["leak_check.h"],
}),
deps = ["//absl/base:core_headers"],
)
# Adding a dependency to leak_check_disable will disable
# sanitizer leak checking (asan/lsan) in a test without
# the need to mess around with build features.
cc_library(
name = "leak_check_disable",
srcs = ["leak_check_disable.cc"],
linkstatic = 1,
alwayslink = 1,
)
# These targets exists for use in tests only, explicitly configuring the
# LEAK_SANITIZER macro. It must be linked with -fsanitize=leak for lsan.
ABSL_LSAN_LINKOPTS = select({
"//absl:llvm_compiler": ["-fsanitize=leak"],
"//conditions:default": [],
})
cc_library(
name = "leak_check_api_enabled_for_testing",
testonly = 1,
srcs = ["leak_check.cc"],
hdrs = ["leak_check.h"],
copts = select({
"//absl:llvm_compiler": ["-DLEAK_SANITIZER"],
"//conditions:default": [],
}),
visibility = ["//visibility:private"],
)
cc_library(
name = "leak_check_api_disabled_for_testing",
testonly = 1,
srcs = ["leak_check.cc"],
hdrs = ["leak_check.h"],
copts = ["-ULEAK_SANITIZER"],
visibility = ["//visibility:private"],
)
cc_test(
name = "leak_check_test",
srcs = ["leak_check_test.cc"],
copts = select({
"//absl:llvm_compiler": ["-DABSL_EXPECT_LEAK_SANITIZER"],
"//conditions:default": [],
}),
linkopts = ABSL_LSAN_LINKOPTS,
deps = [
":leak_check_api_enabled_for_testing",
"//absl/base",
"@com_google_googletest//:gtest_main",
],
)
cc_test(
name = "leak_check_no_lsan_test",
srcs = ["leak_check_test.cc"],
copts = ["-UABSL_EXPECT_LEAK_SANITIZER"],
deps = [
":leak_check_api_disabled_for_testing",
"//absl/base", # for raw_logging
"@com_google_googletest//:gtest_main",
],
)
# Test that leak checking is skipped when lsan is enabled but
# ":leak_check_disable" is linked in.
#
# This test should fail in the absence of a dependency on ":leak_check_disable"
cc_test(
name = "disabled_leak_check_test",
srcs = ["leak_check_fail_test.cc"],
linkopts = ABSL_LSAN_LINKOPTS,
deps = [
":leak_check_api_enabled_for_testing",
":leak_check_disable",
"//absl/base",
"@com_google_googletest//:gtest_main",
],
)

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absl/debugging/internal/address_is_readable.cc Normal file
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// Copyright 2017 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
//
// http://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.
// base::AddressIsReadable() probes an address to see whether it is readable,
// without faulting.
#include "absl/debugging/internal/address_is_readable.h"
#if !defined(__linux__) || defined(__ANDROID__)
namespace absl {
namespace debug_internal {
// On platforms other than Linux, just return true.
bool AddressIsReadable(const void* /* addr */) { return true; }
} // namespace debug_internal
} // namespace absl
#else
#include <fcntl.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <atomic>
#include <cerrno>
#include <cstdint>
#include "absl/base/internal/raw_logging.h"
namespace absl {
namespace debug_internal {
// Pack a pid and two file descriptors into a 64-bit word,
// using 16, 24, and 24 bits for each respectively.
static uint64_t Pack(uint64_t pid, uint64_t read_fd, uint64_t write_fd) {
ABSL_RAW_CHECK((read_fd >> 24) == 0 && (write_fd >> 24) == 0,
"fd out of range");
return (pid << 48) | ((read_fd & 0xffffff) << 24) | (write_fd & 0xffffff);
}
// Unpack x into a pid and two file descriptors, where x was created with
// Pack().
static void Unpack(uint64_t x, int *pid, int *read_fd, int *write_fd) {
*pid = x >> 48;
*read_fd = (x >> 24) & 0xffffff;
*write_fd = x & 0xffffff;
}
// Return whether the byte at *addr is readable, without faulting.
// Save and restores errno. Returns true on systems where
// unimplemented.
// This is a namespace-scoped variable for correct zero-initialization.
static std::atomic<uint64_t> pid_and_fds; // initially 0, an invalid pid.
bool AddressIsReadable(const void *addr) {
int save_errno = errno;
// We test whether a byte is readable by using write(). Normally, this would
// be done via a cached file descriptor to /dev/null, but linux fails to
// check whether the byte is readable when the destination is /dev/null, so
// we use a cached pipe. We store the pid of the process that created the
// pipe to handle the case where a process forks, and the child closes all
// the file descriptors and then calls this routine. This is not perfect:
// the child could use the routine, then close all file descriptors and then
// use this routine again. But the likely use of this routine is when
// crashing, to test the validity of pages when dumping the stack. Beware
// that we may leak file descriptors, but we're unlikely to leak many.
int bytes_written;
int current_pid = getpid() & 0xffff; // we use only the low order 16 bits
do { // until we do not get EBADF trying to use file descriptors
int pid;
int read_fd;
int write_fd;
uint64_t local_pid_and_fds = pid_and_fds.load(std::memory_order_relaxed);
Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
while (current_pid != pid) {
int p[2];
// new pipe
if (pipe(p) != 0) {
ABSL_RAW_LOG(FATAL, "Failed to create pipe, errno=%d", errno);
}
fcntl(p[0], F_SETFD, FD_CLOEXEC);
fcntl(p[1], F_SETFD, FD_CLOEXEC);
uint64_t new_pid_and_fds = Pack(current_pid, p[0], p[1]);
if (pid_and_fds.compare_exchange_strong(
local_pid_and_fds, new_pid_and_fds, std::memory_order_relaxed,
std::memory_order_relaxed)) {
local_pid_and_fds = new_pid_and_fds; // fds exposed to other threads
} else { // fds not exposed to other threads; we can close them.
close(p[0]);
close(p[1]);
local_pid_and_fds = pid_and_fds.load(std::memory_order_relaxed);
}
Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
}
errno = 0;
// Use syscall(SYS_write, ...) instead of write() to prevent ASAN
// and other checkers from complaining about accesses to arbitrary
// memory.
do {
bytes_written = syscall(SYS_write, write_fd, addr, 1);
} while (bytes_written == -1 && errno == EINTR);
if (bytes_written == 1) { // remove the byte from the pipe
char c;
while (read(read_fd, &c, 1) == -1 && errno == EINTR) {
}
}
if (errno == EBADF) { // Descriptors invalid.
// If pid_and_fds contains the problematic file descriptors we just used,
// this call will forget them, and the loop will try again.
pid_and_fds.compare_exchange_strong(local_pid_and_fds, 0,
std::memory_order_relaxed,
std::memory_order_relaxed);
}
} while (errno == EBADF);
errno = save_errno;
return bytes_written == 1;
}
} // namespace debug_internal
} // namespace absl
#endif

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// Copyright 2017 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
//
// http://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.
//
#ifndef ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
#define ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
namespace absl {
namespace debug_internal {
// Return whether the byte at *addr is readable, without faulting.
// Save and restores errno.
bool AddressIsReadable(const void *addr);
} // namespace debug_internal
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_

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// Copyright 2017 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
//
// http://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.
// Allow dynamic symbol lookup in an in-memory Elf image.
//
#include "absl/debugging/internal/elf_mem_image.h"
#ifdef ABSL_HAVE_ELF_MEM_IMAGE // defined in elf_mem_image.h
#include <string.h>
#include <cassert>
#include <cstddef>
#include "absl/base/internal/raw_logging.h"
// From binutils/include/elf/common.h (this doesn't appear to be documented
// anywhere else).
//
// /* This flag appears in a Versym structure. It means that the symbol
// is hidden, and is only visible with an explicit version number.
// This is a GNU extension. */
// #define VERSYM_HIDDEN 0x8000
//
// /* This is the mask for the rest of the Versym information. */
// #define VERSYM_VERSION 0x7fff
#define VERSYM_VERSION 0x7fff
namespace absl {
namespace debug_internal {
namespace {
#if __WORDSIZE == 32
const int kElfClass = ELFCLASS32;
int ElfBind(const ElfW(Sym) *symbol) { return ELF32_ST_BIND(symbol->st_info); }
int ElfType(const ElfW(Sym) *symbol) { return ELF32_ST_TYPE(symbol->st_info); }
#elif __WORDSIZE == 64
const int kElfClass = ELFCLASS64;
int ElfBind(const ElfW(Sym) *symbol) { return ELF64_ST_BIND(symbol->st_info); }
int ElfType(const ElfW(Sym) *symbol) { return ELF64_ST_TYPE(symbol->st_info); }
#else
const int kElfClass = -1;
int ElfBind(const ElfW(Sym) *) {
ABSL_RAW_LOG(FATAL, "Unexpected word size");
return 0;
}
int ElfType(const ElfW(Sym) *) {
ABSL_RAW_LOG(FATAL, "Unexpected word size");
return 0;
}
#endif
// Extract an element from one of the ELF tables, cast it to desired type.
// This is just a simple arithmetic and a glorified cast.
// Callers are responsible for bounds checking.
template <typename T>
const T *GetTableElement(const ElfW(Ehdr) * ehdr, ElfW(Off) table_offset,
ElfW(Word) element_size, size_t index) {
return reinterpret_cast<const T*>(reinterpret_cast<const char *>(ehdr)
+ table_offset
+ index * element_size);
}
} // namespace
const void *const ElfMemImage::kInvalidBase =
reinterpret_cast<const void *>(~0L);
ElfMemImage::ElfMemImage(const void *base) {
ABSL_RAW_CHECK(base != kInvalidBase, "bad pointer");
Init(base);
}
int ElfMemImage::GetNumSymbols() const {
if (!hash_) {
return 0;
}
// See http://www.caldera.com/developers/gabi/latest/ch5.dynamic.html#hash
return hash_[1];
}
const ElfW(Sym) *ElfMemImage::GetDynsym(int index) const {
ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
return dynsym_ + index;
}
const ElfW(Versym) *ElfMemImage::GetVersym(int index) const {
ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
return versym_ + index;
}
const ElfW(Phdr) *ElfMemImage::GetPhdr(int index) const {
ABSL_RAW_CHECK(index < ehdr_->e_phnum, "index out of range");
return GetTableElement<ElfW(Phdr)>(ehdr_,
ehdr_->e_phoff,
ehdr_->e_phentsize,
index);
}
const char *ElfMemImage::GetDynstr(ElfW(Word) offset) const {
ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
return dynstr_ + offset;
}
const void *ElfMemImage::GetSymAddr(const ElfW(Sym) *sym) const {
if (sym->st_shndx == SHN_UNDEF || sym->st_shndx >= SHN_LORESERVE) {
// Symbol corresponds to "special" (e.g. SHN_ABS) section.
return reinterpret_cast<const void *>(sym->st_value);
}
ABSL_RAW_CHECK(link_base_ < sym->st_value, "symbol out of range");
return GetTableElement<char>(ehdr_, 0, 1, sym->st_value) - link_base_;
}
const ElfW(Verdef) *ElfMemImage::GetVerdef(int index) const {
ABSL_RAW_CHECK(0 <= index && static_cast<size_t>(index) <= verdefnum_,
"index out of range");
const ElfW(Verdef) *version_definition = verdef_;
while (version_definition->vd_ndx < index && version_definition->vd_next) {
const char *const version_definition_as_char =
reinterpret_cast<const char *>(version_definition);
version_definition =
reinterpret_cast<const ElfW(Verdef) *>(version_definition_as_char +
version_definition->vd_next);
}
return version_definition->vd_ndx == index ? version_definition : nullptr;
}
const ElfW(Verdaux) *ElfMemImage::GetVerdefAux(
const ElfW(Verdef) *verdef) const {
return reinterpret_cast<const ElfW(Verdaux) *>(verdef+1);
}
const char *ElfMemImage::GetVerstr(ElfW(Word) offset) const {
ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
return dynstr_ + offset;
}
void ElfMemImage::Init(const void *base) {
ehdr_ = nullptr;
dynsym_ = nullptr;
dynstr_ = nullptr;
versym_ = nullptr;
verdef_ = nullptr;
hash_ = nullptr;
strsize_ = 0;
verdefnum_ = 0;
link_base_ = ~0L; // Sentinel: PT_LOAD .p_vaddr can't possibly be this.
if (!base) {
return;
}
const intptr_t base_as_uintptr_t = reinterpret_cast<uintptr_t>(base);
// Fake VDSO has low bit set.
const bool fake_vdso = ((base_as_uintptr_t & 1) != 0);
base = reinterpret_cast<const void *>(base_as_uintptr_t & ~1);
const char *const base_as_char = reinterpret_cast<const char *>(base);
if (base_as_char[EI_MAG0] != ELFMAG0 || base_as_char[EI_MAG1] != ELFMAG1 ||
base_as_char[EI_MAG2] != ELFMAG2 || base_as_char[EI_MAG3] != ELFMAG3) {
assert(false);
return;
}
int elf_class = base_as_char[EI_CLASS];
if (elf_class != kElfClass) {
assert(false);
return;
}
switch (base_as_char[EI_DATA]) {
case ELFDATA2LSB: {
if (__LITTLE_ENDIAN != __BYTE_ORDER) {
assert(false);
return;
}
break;
}
case ELFDATA2MSB: {
if (__BIG_ENDIAN != __BYTE_ORDER) {
assert(false);
return;
}
break;
}
default: {
assert(false);
return;
}
}
ehdr_ = reinterpret_cast<const ElfW(Ehdr) *>(base);
const ElfW(Phdr) *dynamic_program_header = nullptr;
for (int i = 0; i < ehdr_->e_phnum; ++i) {
const ElfW(Phdr) *const program_header = GetPhdr(i);
switch (program_header->p_type) {
case PT_LOAD:
if (!~link_base_) {
link_base_ = program_header->p_vaddr;
}
break;
case PT_DYNAMIC:
dynamic_program_header = program_header;
break;
}
}
if (!~link_base_ || !dynamic_program_header) {
assert(false);
// Mark this image as not present. Can not recur infinitely.
Init(nullptr);
return;
}
ptrdiff_t relocation =
base_as_char - reinterpret_cast<const char *>(link_base_);
ElfW(Dyn) *dynamic_entry =
reinterpret_cast<ElfW(Dyn) *>(dynamic_program_header->p_vaddr +
relocation);
for (; dynamic_entry->d_tag != DT_NULL; ++dynamic_entry) {
ElfW(Xword) value = dynamic_entry->d_un.d_val;
if (fake_vdso) {
// A complication: in the real VDSO, dynamic entries are not relocated
// (it wasn't loaded by a dynamic loader). But when testing with a
// "fake" dlopen()ed vdso library, the loader relocates some (but
// not all!) of them before we get here.
if (dynamic_entry->d_tag == DT_VERDEF) {
// The only dynamic entry (of the ones we care about) libc-2.3.6
// loader doesn't relocate.
value += relocation;
}
} else {
// Real VDSO. Everything needs to be relocated.
value += relocation;
}
switch (dynamic_entry->d_tag) {
case DT_HASH:
hash_ = reinterpret_cast<ElfW(Word) *>(value);
break;
case DT_SYMTAB:
dynsym_ = reinterpret_cast<ElfW(Sym) *>(value);
break;
case DT_STRTAB:
dynstr_ = reinterpret_cast<const char *>(value);
break;
case DT_VERSYM:
versym_ = reinterpret_cast<ElfW(Versym) *>(value);
break;
case DT_VERDEF:
verdef_ = reinterpret_cast<ElfW(Verdef) *>(value);
break;
case DT_VERDEFNUM:
verdefnum_ = dynamic_entry->d_un.d_val;
break;
case DT_STRSZ:
strsize_ = dynamic_entry->d_un.d_val;
break;
default:
// Unrecognized entries explicitly ignored.
break;
}
}
if (!hash_ || !dynsym_ || !dynstr_ || !versym_ ||
!verdef_ || !verdefnum_ || !strsize_) {
assert(false); // invalid VDSO
// Mark this image as not present. Can not recur infinitely.
Init(nullptr);
return;
}
}
bool ElfMemImage::LookupSymbol(const char *name,
const char *version,
int type,
SymbolInfo *info_out) const {
for (const SymbolInfo& info : *this) {
if (strcmp(info.name, name) == 0 && strcmp(info.version, version) == 0 &&
ElfType(info.symbol) == type) {
if (info_out) {
*info_out = info;
}
return true;
}
}
return false;
}
bool ElfMemImage::LookupSymbolByAddress(const void *address,
SymbolInfo *info_out) const {
for (const SymbolInfo& info : *this) {
const char *const symbol_start =
reinterpret_cast<const char *>(info.address);
const char *const symbol_end = symbol_start + info.symbol->st_size;
if (symbol_start <= address && address < symbol_end) {
if (info_out) {
// Client wants to know details for that symbol (the usual case).
if (ElfBind(info.symbol) == STB_GLOBAL) {
// Strong symbol; just return it.
*info_out = info;
return true;
} else {
// Weak or local. Record it, but keep looking for a strong one.
*info_out = info;
}
} else {
// Client only cares if there is an overlapping symbol.
return true;
}
}
}
return false;
}
ElfMemImage::SymbolIterator::SymbolIterator(const void *const image, int index)
: index_(index), image_(image) {
}
const ElfMemImage::SymbolInfo *ElfMemImage::SymbolIterator::operator->() const {
return &info_;
}
const ElfMemImage::SymbolInfo& ElfMemImage::SymbolIterator::operator*() const {
return info_;
}
bool ElfMemImage::SymbolIterator::operator==(const SymbolIterator &rhs) const {
return this->image_ == rhs.image_ && this->index_ == rhs.index_;
}
bool ElfMemImage::SymbolIterator::operator!=(const SymbolIterator &rhs) const {
return !(*this == rhs);
}
ElfMemImage::SymbolIterator &ElfMemImage::SymbolIterator::operator++() {
this->Update(1);
return *this;
}
ElfMemImage::SymbolIterator ElfMemImage::begin() const {
SymbolIterator it(this, 0);
it.Update(0);
return it;
}
ElfMemImage::SymbolIterator ElfMemImage::end() const {
return SymbolIterator(this, GetNumSymbols());
}
void ElfMemImage::SymbolIterator::Update(int increment) {
const ElfMemImage *image = reinterpret_cast<const ElfMemImage *>(image_);
ABSL_RAW_CHECK(image->IsPresent() || increment == 0, "");
if (!image->IsPresent()) {
return;
}
index_ += increment;
if (index_ >= image->GetNumSymbols()) {
index_ = image->GetNumSymbols();
return;
}
const ElfW(Sym) *symbol = image->GetDynsym(index_);
const ElfW(Versym) *version_symbol = image->GetVersym(index_);
ABSL_RAW_CHECK(symbol && version_symbol, "");
const char *const symbol_name = image->GetDynstr(symbol->st_name);
const ElfW(Versym) version_index = version_symbol[0] & VERSYM_VERSION;
const ElfW(Verdef) *version_definition = nullptr;
const char *version_name = "";
if (symbol->st_shndx == SHN_UNDEF) {
// Undefined symbols reference DT_VERNEED, not DT_VERDEF, and
// version_index could well be greater than verdefnum_, so calling
// GetVerdef(version_index) may trigger assertion.
} else {
version_definition = image->GetVerdef(version_index);
}
if (version_definition) {
// I am expecting 1 or 2 auxiliary entries: 1 for the version itself,
// optional 2nd if the version has a parent.
ABSL_RAW_CHECK(
version_definition->vd_cnt == 1 || version_definition->vd_cnt == 2,
"wrong number of entries");
const ElfW(Verdaux) *version_aux = image->GetVerdefAux(version_definition);
version_name = image->GetVerstr(version_aux->vda_name);
}
info_.name = symbol_name;
info_.version = version_name;
info_.address = image->GetSymAddr(symbol);
info_.symbol = symbol;
}
} // namespace debug_internal
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE

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/*
* Copyright 2017 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
*
* http://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.
*/
// Allow dynamic symbol lookup for in-memory Elf images.
#ifndef ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
#define ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
// Including this will define the __GLIBC__ macro if glibc is being
// used.
#include <climits>
// Maybe one day we can rewrite this file not to require the elf
// symbol extensions in glibc, but for right now we need them.
#ifdef ABSL_HAVE_ELF_MEM_IMAGE
#error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set
#endif
#if defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \
!defined(__asmjs__)
#define ABSL_HAVE_ELF_MEM_IMAGE 1
#endif
#if ABSL_HAVE_ELF_MEM_IMAGE
#include <link.h> // for ElfW
namespace absl {
namespace debug_internal {
// An in-memory ELF image (may not exist on disk).
class ElfMemImage {
public:
// Sentinel: there could never be an elf image at this address.
static const void *const kInvalidBase;
// Information about a single vdso symbol.
// All pointers are into .dynsym, .dynstr, or .text of the VDSO.
// Do not free() them or modify through them.
struct SymbolInfo {
const char *name; // E.g. "__vdso_getcpu"
const char *version; // E.g. "LINUX_2.6", could be ""
// for unversioned symbol.
const void *address; // Relocated symbol address.
const ElfW(Sym) *symbol; // Symbol in the dynamic symbol table.
};
// Supports iteration over all dynamic symbols.
class SymbolIterator {
public:
friend class ElfMemImage;
const SymbolInfo *operator->() const;
const SymbolInfo &operator*() const;
SymbolIterator& operator++();
bool operator!=(const SymbolIterator &rhs) const;
bool operator==(const SymbolIterator &rhs) const;
private:
SymbolIterator(const void *const image, int index);
void Update(int incr);
SymbolInfo info_;
int index_;
const void *const image_;
};
explicit ElfMemImage(const void *base);
void Init(const void *base);
bool IsPresent() const { return ehdr_ != nullptr; }
const ElfW(Phdr)* GetPhdr(int index) const;
const ElfW(Sym)* GetDynsym(int index) const;
const ElfW(Versym)* GetVersym(int index) const;
const ElfW(Verdef)* GetVerdef(int index) const;
const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const;
const char* GetDynstr(ElfW(Word) offset) const;
const void* GetSymAddr(const ElfW(Sym) *sym) const;
const char* GetVerstr(ElfW(Word) offset) const;
int GetNumSymbols() const;
SymbolIterator begin() const;
SymbolIterator end() const;
// Look up versioned dynamic symbol in the image.
// Returns false if image is not present, or doesn't contain given
// symbol/version/type combination.
// If info_out is non-null, additional details are filled in.
bool LookupSymbol(const char *name, const char *version,
int symbol_type, SymbolInfo *info_out) const;
// Find info about symbol (if any) which overlaps given address.
// Returns true if symbol was found; false if image isn't present
// or doesn't have a symbol overlapping given address.
// If info_out is non-null, additional details are filled in.
bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
private:
const ElfW(Ehdr) *ehdr_;
const ElfW(Sym) *dynsym_;
const ElfW(Versym) *versym_;
const ElfW(Verdef) *verdef_;
const ElfW(Word) *hash_;
const char *dynstr_;
size_t strsize_;
size_t verdefnum_;
ElfW(Addr) link_base_; // Link-time base (p_vaddr of first PT_LOAD).
};
} // namespace debug_internal
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE
#endif // ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_

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#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
// Generate stack tracer for aarch64
#if defined(__linux__)
#include <sys/mman.h>
#include <ucontext.h>
#include <unistd.h>
#endif
#include <atomic>
#include <cassert>
#include <cstdint>
#include <iostream>
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
#include "absl/debugging/stacktrace.h"
static const uintptr_t kUnknownFrameSize = 0;
#if defined(__linux__)
// Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
static const unsigned char* GetKernelRtSigreturnAddress() {
constexpr uintptr_t kImpossibleAddress = 1;
static std::atomic<uintptr_t> memoized{kImpossibleAddress};
uintptr_t address = memoized.load(std::memory_order_relaxed);
if (address != kImpossibleAddress) {
return reinterpret_cast<const unsigned char*>(address);
}
address = reinterpret_cast<uintptr_t>(nullptr);
#ifdef ABSL_HAVE_VDSO_SUPPORT
absl::debug_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debug_internal::VDSOSupport::SymbolInfo symbol_info;
if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.6.39", STT_FUNC,
&symbol_info) ||
symbol_info.address == nullptr) {
// Unexpected: VDSO is present, yet the expected symbol is missing
// or null.
assert(false && "VDSO is present, but doesn't have expected symbol");
} else {
if (reinterpret_cast<uintptr_t>(symbol_info.address) !=
kImpossibleAddress) {
address = reinterpret_cast<uintptr_t>(symbol_info.address);
} else {
assert(false && "VDSO returned invalid address");
}
}
}
#endif
memoized.store(address, std::memory_order_relaxed);
return reinterpret_cast<const unsigned char*>(address);
}
#endif // __linux__
// Compute the size of a stack frame in [low..high). We assume that
// low < high. Return size of kUnknownFrameSize.
template<typename T>
static inline uintptr_t ComputeStackFrameSize(const T* low,
const T* high) {
const char* low_char_ptr = reinterpret_cast<const char *>(low);
const char* high_char_ptr = reinterpret_cast<const char *>(high);
return low < high ? high_char_ptr - low_char_ptr : kUnknownFrameSize;
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING, bool WITH_CONTEXT>
static void **NextStackFrame(void **old_frame_pointer, const void *uc) {
void **new_frame_pointer = reinterpret_cast<void**>(*old_frame_pointer);
bool check_frame_size = true;
#if defined(__linux__)
if (WITH_CONTEXT && uc != nullptr) {
// Check to see if next frame's return address is __kernel_rt_sigreturn.
if (old_frame_pointer[1] == GetKernelRtSigreturnAddress()) {
const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
// old_frame_pointer[0] is not suitable for unwinding, look at
// ucontext to discover frame pointer before signal.
void **const pre_signal_frame_pointer =
reinterpret_cast<void **>(ucv->uc_mcontext.regs[29]);
// Check that alleged frame pointer is actually readable. This is to
// prevent "double fault" in case we hit the first fault due to e.g.
// stack corruption.
if (!absl::debug_internal::AddressIsReadable(
pre_signal_frame_pointer))
return nullptr;
// Alleged frame pointer is readable, use it for further unwinding.
new_frame_pointer = pre_signal_frame_pointer;
// Skip frame size check if we return from a signal. We may be using a
// an alternate stack for signals.
check_frame_size = false;
}
}
#endif
// aarch64 ABI requires stack pointer to be 16-byte-aligned.
if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 15) != 0)
return nullptr;
// Check frame size. In strict mode, we assume frames to be under
// 100,000 bytes. In non-strict mode, we relax the limit to 1MB.
if (check_frame_size) {
const uintptr_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
const uintptr_t frame_size =
ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
if (frame_size == kUnknownFrameSize || frame_size > max_size)
return nullptr;
}
return new_frame_pointer;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
#ifdef __GNUC__
void **frame_pointer = reinterpret_cast<void**>(__builtin_frame_address(0));
#else
# error reading stack point not yet supported on this platform.
#endif
skip_count++; // Skip the frame for this function.
int n = 0;
// The frame pointer points to low address of a frame. The first 64-bit
// word of a frame points to the next frame up the call chain, which normally
// is just after the high address of the current frame. The second word of
// a frame contains return adress of to the caller. To find a pc value
// associated with the current frame, we need to go down a level in the call
// chain. So we remember return the address of the last frame seen. This
// does not work for the first stack frame, which belongs to UnwindImp() but
// we skip the frame for UnwindImp() anyway.
void* prev_return_address = nullptr;
while (frame_pointer && n < max_depth) {
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few bogus
// entries in some rare cases).
void **next_frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = prev_return_address;
if (IS_STACK_FRAMES) {
sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer);
}
n++;
}
prev_return_address = frame_pointer[1];
frame_pointer = next_frame_pointer;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int j = 0;
for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
}
*min_dropped_frames = j;
}
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_

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// Copyright 2011 and onwards Google Inc.
// All rights reserved.
//
// Author: Doug Kwan
// This is inspired by Craig Silverstein's PowerPC stacktrace code.
//
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
#include <cstdint>
#include "absl/debugging/stacktrace.h"
// WARNING:
// This only works if all your code is in either ARM or THUMB mode. With
// interworking, the frame pointer of the caller can either be in r11 (ARM
// mode) or r7 (THUMB mode). A callee only saves the frame pointer of its
// mode in a fixed location on its stack frame. If the caller is a different
// mode, there is no easy way to find the frame pointer. It can either be
// still in the designated register or saved on stack along with other callee
// saved registers.
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return nullptr if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING>
static void **NextStackFrame(void **old_sp) {
void **new_sp = (void**) old_sp[-1];
// Check that the transition from frame pointer old_sp to frame
// pointer new_sp isn't clearly bogus
if (STRICT_UNWINDING) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_sp <= old_sp) return nullptr;
// Assume stack frames larger than 100,000 bytes are bogus.
if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
} else {
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_sp == old_sp) return nullptr;
// And allow frames upto about 1MB.
if ((new_sp > old_sp)
&& ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
}
if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return nullptr;
return new_sp;
}
// This ensures that absl::GetStackTrace sets up the Link Register properly.
#ifdef __GNUC__
void StacktraceArmDummyFunction() __attribute__((noinline));
void StacktraceArmDummyFunction() { __asm__ volatile(""); }
#else
# error StacktraceArmDummyFunction() needs to be ported to this platform.
#endif
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void * /* ucp */, int *min_dropped_frames) {
#ifdef __GNUC__
void **sp = reinterpret_cast<void**>(__builtin_frame_address(0));
#else
# error reading stack point not yet supported on this platform.
#endif
// On ARM, the return address is stored in the link register (r14).
// This is not saved on the stack frame of a leaf function. To
// simplify code that reads return addresses, we call a dummy
// function so that the return address of this function is also
// stored in the stack frame. This works at least for gcc.
StacktraceArmDummyFunction();
int n = 0;
while (sp && n < max_depth) {
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few bogus
// entries in some rare cases).
void **next_sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = *sp;
if (IS_STACK_FRAMES) {
if (next_sp > sp) {
sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
sp = next_sp;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int j = 0;
for (; sp != nullptr && j < kMaxUnwind; j++) {
sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
}
*min_dropped_frames = j;
}
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_

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/*
* Copyright 2017 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
*
* http://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.
* Defines ABSL_STACKTRACE_INL_HEADER to the *-inl.h containing
* actual unwinder implementation.
* This header is "private" to stacktrace.cc.
* DO NOT include it into any other files.
*/
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
// First, test platforms which only support a stub.
#if ABSL_STACKTRACE_INL_HEADER
#error ABSL_STACKTRACE_INL_HEADER cannot be directly set
#elif defined(__native_client__) || defined(__APPLE__) || \
defined(__ANDROID__) || defined(__myriad2__) || defined(__asmjs__) || \
defined(__Fuchsia__) || defined(__GENCLAVE__) || \
defined(GOOGLE_UNSUPPORTED_OS_HERCULES)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_unimplemented-inl.inc"
// Next, test for Mips and Windows.
// TODO(marmstrong): http://b/21334018: Mips case, remove the check for
// ABSL_STACKTRACE_INL_HEADER.
#elif defined(__mips__) && !defined(ABSL_STACKTRACE_INL_HEADER)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_unimplemented-inl.inc"
#elif defined(_WIN32) // windows
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_win32-inl.inc"
// Finally, test NO_FRAME_POINTER.
#elif !defined(NO_FRAME_POINTER)
# if defined(__i386__) || defined(__x86_64__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_x86-inl.inc"
# elif defined(__ppc__) || defined(__PPC__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_powerpc-inl.inc"
# elif defined(__aarch64__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_aarch64-inl.inc"
# elif defined(__arm__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_arm-inl.inc"
# endif
#else // defined(NO_FRAME_POINTER)
# if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_unimplemented-inl.inc"
# elif defined(__ppc__) || defined(__PPC__)
// Use glibc's backtrace.
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_generic-inl.inc"
# elif defined(__arm__)
# error stacktrace without frame pointer is not supported on ARM
# endif
#endif // NO_FRAME_POINTER
#if !defined(ABSL_STACKTRACE_INL_HEADER)
#error Not supported yet
#endif
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_

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// Copyright 2000 - 2007 Google Inc.
// All rights reserved.
//
// Author: Sanjay Ghemawat
//
// Portable implementation - just use glibc
//
// Note: The glibc implementation may cause a call to malloc.
// This can cause a deadlock in HeapProfiler.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
#include <execinfo.h>
#include <cstring>
#include "absl/debugging/stacktrace.h"
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
static const int kStackLength = 64;
void * stack[kStackLength];
int size;
size = backtrace(stack, kStackLength);
skip_count++; // we want to skip the current frame as well
int result_count = size - skip_count;
if (result_count < 0)
result_count = 0;
if (result_count > max_depth)
result_count = max_depth;
for (int i = 0; i < result_count; i++)
result[i] = stack[i + skip_count];
if (IS_STACK_FRAMES) {
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * result_count);
}
if (min_dropped_frames != nullptr) {
if (size - skip_count - max_depth > 0) {
*min_dropped_frames = size - skip_count - max_depth;
} else {
*min_dropped_frames = 0;
}
}
return result_count;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_

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// Copyright 2017 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
//
// http://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.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_LIBUNWIND_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_LIBUNWIND_INL_H_
// We only need local unwinder.
#define UNW_LOCAL_ONLY
extern "C" {
#include "third_party/libunwind/include/libunwind.h"
}
#include "absl/debugging/stacktrace.h"
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/raw_logging.h"
// Sometimes, we can try to get a stack trace from within a stack
// trace, because we don't block signals inside libunwind (which would be too
// expensive: the two extra system calls per stack trace do matter here).
// That can cause a self-deadlock (as in http://b/5722312).
// Protect against such reentrant call by failing to get a stack trace.
//
// We use __thread here because the code here is extremely low level -- it is
// called while collecting stack traces from within malloc and mmap, and thus
// can not call anything which might call malloc or mmap itself.
// In particular, using PerThread or STATIC_THREAD_LOCAL_POD
// here will cause infinite recursion for at least dbg/piii builds with
// crosstool-v12.
static __thread int recursive;
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *, int *min_dropped_frames) {
if (recursive) {
return 0;
}
++recursive;
int n = 0;
if (IS_STACK_FRAMES) {
void *ip;
unw_cursor_t cursor;
unw_context_t uc;
unw_word_t sp = 0, next_sp = 0;
unw_getcontext(&uc);
ABSL_RAW_CHECK(unw_init_local(&cursor, &uc) >= 0, "unw_init_local failed");
skip_count++; // Do not include current frame
while (skip_count--) {
if (unw_step(&cursor) <= 0) {
goto out;
}
if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp)) {
goto out;
}
}
while (n < max_depth) {
if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
break;
}
sizes[n] = 0;
result[n++] = ip;
if (unw_step(&cursor) <= 0) {
break;
}
sp = next_sp;
if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp) , 0) {
break;
}
sizes[n - 1] = next_sp - sp;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int j = 0;
for (; j < kMaxUnwind; j++) {
if (unw_step(&cursor) < 0) {
break;
}
}
*min_dropped_frames = j;
}
} else {
skip_count++; // Do not include current frame.
void **result_all = reinterpret_cast<void**>(
alloca(sizeof(void*) * (max_depth + skip_count)));
int rc = unw_backtrace(result_all, max_depth + skip_count);
if (rc > 0) {
// Tell MSan that result_all has been initialized. b/34965936.
ANNOTATE_MEMORY_IS_INITIALIZED(result_all, rc * sizeof(void*));
}
if (rc > skip_count) {
memcpy(result, &result_all[skip_count],
sizeof(void*) * (rc - skip_count));
n = rc - skip_count;
} else {
n = 0;
}
if (min_dropped_frames != nullptr) {
// Not implemented.
*min_dropped_frames = 0;
}
}
out:
--recursive;
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_LIBUNWIND_INL_H_

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// Copyright 2017 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
//
// http://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.
//
// Produce stack trace. I'm guessing (hoping!) the code is much like
// for x86. For apple machines, at least, it seems to be; see
// http://developer.apple.com/documentation/mac/runtimehtml/RTArch-59.html
// http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
// Linux has similar code: http://patchwork.ozlabs.org/linuxppc/patch?id=8882
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
#if defined(__linux__)
#include <asm/ptrace.h> // for PT_NIP.
#include <ucontext.h> // for ucontext_t
#endif
#include <unistd.h>
#include <cassert>
#include <cstdint>
#include <cstdio>
#include "absl/base/port.h"
#include "absl/debugging/stacktrace.h"
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
// Given a stack pointer, return the saved link register value.
// Note that this is the link register for a callee.
static inline void *StacktracePowerPCGetLR(void **sp) {
// PowerPC has 3 main ABIs, which say where in the stack the
// Link Register is. For DARWIN and AIX (used by apple and
// linux ppc64), it's in sp[2]. For SYSV (used by linux ppc),
// it's in sp[1].
#if defined(_CALL_AIX) || defined(_CALL_DARWIN)
return *(sp+2);
#elif defined(_CALL_SYSV)
return *(sp+1);
#elif defined(__APPLE__) || (defined(__linux__) && defined(__PPC64__))
// This check is in case the compiler doesn't define _CALL_AIX/etc.
return *(sp+2);
#elif defined(__linux)
// This check is in case the compiler doesn't define _CALL_SYSV.
return *(sp+1);
#else
#error Need to specify the PPC ABI for your archiecture.
#endif
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void **NextStackFrame(void **old_sp, const void *uc) {
void **new_sp = (void **) *old_sp;
enum { kStackAlignment = 16 };
// Check that the transition from frame pointer old_sp to frame
// pointer new_sp isn't clearly bogus
if (STRICT_UNWINDING) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_sp <= old_sp) return nullptr;
// Assume stack frames larger than 100,000 bytes are bogus.
if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
} else {
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_sp == old_sp) return nullptr;
// And allow frames upto about 1MB.
if ((new_sp > old_sp)
&& ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
}
if ((uintptr_t)new_sp % kStackAlignment != 0) return nullptr;
#if defined(__linux__)
enum StackTraceKernelSymbolStatus {
kNotInitialized = 0, kAddressValid, kAddressInvalid };
if (IS_WITH_CONTEXT && uc != nullptr) {
static StackTraceKernelSymbolStatus kernel_symbol_status =
kNotInitialized; // Sentinel: not computed yet.
// Initialize with sentinel value: __kernel_rt_sigtramp_rt64 can not
// possibly be there.
static const unsigned char *kernel_sigtramp_rt64_address = nullptr;
if (kernel_symbol_status == kNotInitialized) {
absl::debug_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debug_internal::VDSOSupport::SymbolInfo
sigtramp_rt64_symbol_info;
if (!vdso.LookupSymbol(
"__kernel_sigtramp_rt64", "LINUX_2.6.15",
absl::debug_internal::VDSOSupport::kVDSOSymbolType,
&sigtramp_rt64_symbol_info) ||
sigtramp_rt64_symbol_info.address == nullptr) {
// Unexpected: VDSO is present, yet the expected symbol is missing
// or null.
assert(false && "VDSO is present, but doesn't have expected symbol");
kernel_symbol_status = kAddressInvalid;
} else {
kernel_sigtramp_rt64_address =
reinterpret_cast<const unsigned char *>(
sigtramp_rt64_symbol_info.address);
kernel_symbol_status = kAddressValid;
}
} else {
kernel_symbol_status = kAddressInvalid;
}
}
if (new_sp != nullptr &&
kernel_symbol_status == kAddressValid &&
StacktracePowerPCGetLR(new_sp) == kernel_sigtramp_rt64_address) {
const ucontext_t* signal_context =
reinterpret_cast<const ucontext_t*>(uc);
void **const sp_before_signal =
reinterpret_cast<void**>(signal_context->uc_mcontext.gp_regs[PT_R1]);
// Check that alleged sp before signal is nonnull and is reasonably
// aligned.
if (sp_before_signal != nullptr &&
((uintptr_t)sp_before_signal % kStackAlignment) == 0) {
// Check that alleged stack pointer is actually readable. This is to
// prevent a "double fault" in case we hit the first fault due to e.g.
// a stack corruption.
if (absl::debug_internal::AddressIsReadable(sp_before_signal)) {
// Alleged stack pointer is readable, use it for further unwinding.
new_sp = sp_before_signal;
}
}
}
}
#endif
return new_sp;
}
// This ensures that absl::GetStackTrace sets up the Link Register properly.
void StacktracePowerPCDummyFunction() __attribute__((noinline));
void StacktracePowerPCDummyFunction() { __asm__ volatile(""); }
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
void **sp;
// Apple OS X uses an old version of gnu as -- both Darwin 7.9.0 (Panther)
// and Darwin 8.8.1 (Tiger) use as 1.38. This means we have to use a
// different asm syntax. I don't know quite the best way to discriminate
// systems using the old as from the new one; I've gone with __APPLE__.
#ifdef __APPLE__
__asm__ volatile ("mr %0,r1" : "=r" (sp));
#else
__asm__ volatile ("mr %0,1" : "=r" (sp));
#endif
// On PowerPC, the "Link Register" or "Link Record" (LR), is a stack
// entry that holds the return address of the subroutine call (what
// instruction we run after our function finishes). This is the
// same as the stack-pointer of our parent routine, which is what we
// want here. While the compiler will always(?) set up LR for
// subroutine calls, it may not for leaf functions (such as this one).
// This routine forces the compiler (at least gcc) to push it anyway.
StacktracePowerPCDummyFunction();
// The LR save area is used by the callee, so the top entry is bogus.
skip_count++;
int n = 0;
// Unlike ABIs of X86 and ARM, PowerPC ABIs say that return address (in
// the link register) of a function call is stored in the caller's stack
// frame instead of the callee's. When we look for the return address
// associated with a stack frame, we need to make sure that there is a
// caller frame before it. So we call NextStackFrame before entering the
// loop below and check next_sp instead of sp for loop termination.
// The outermost frame is set up by runtimes and it does not have a
// caller frame, so it is skipped.
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few
// bogus entries in some rare cases).
void **next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
while (next_sp && n < max_depth) {
if (skip_count > 0) {
skip_count--;
} else {
result[n] = StacktracePowerPCGetLR(sp);
if (IS_STACK_FRAMES) {
if (next_sp > sp) {
sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
sp = next_sp;
next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 1000;
int j = 0;
for (; next_sp != nullptr && j < kMaxUnwind; j++) {
next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(next_sp, ucp);
}
*min_dropped_frames = j;
}
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_

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#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** /* result */, int* /* sizes */,
int /* max_depth */, int /* skip_count */,
const void* /* ucp */, int *min_dropped_frames) {
if (min_dropped_frames != nullptr) {
*min_dropped_frames = 0;
}
return 0;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_

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// Copyright 2017 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
//
// http://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.
//
// Produces a stack trace for Windows. Normally, one could use
// stacktrace_x86-inl.h or stacktrace_x86_64-inl.h -- and indeed, that
// should work for binaries compiled using MSVC in "debug" mode.
// However, in "release" mode, Windows uses frame-pointer
// optimization, which makes getting a stack trace very difficult.
//
// There are several approaches one can take. One is to use Windows
// intrinsics like StackWalk64. These can work, but have restrictions
// on how successful they can be. Another attempt is to write a
// version of stacktrace_x86-inl.h that has heuristic support for
// dealing with FPO, similar to what WinDbg does (see
// http://www.nynaeve.net/?p=97). There are (non-working) examples of
// these approaches, complete with TODOs, in stacktrace_win32-inl.h#1
//
// The solution we've ended up doing is to call the undocumented
// windows function RtlCaptureStackBackTrace, which probably doesn't
// work with FPO but at least is fast, and doesn't require a symbol
// server.
//
// This code is inspired by a patch from David Vitek:
// http://code.google.com/p/google-perftools/issues/detail?id=83
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
#include <windows.h> // for GetProcAddress and GetModuleHandle
#include <cassert>
typedef USHORT NTAPI RtlCaptureStackBackTrace_Function(
IN ULONG frames_to_skip,
IN ULONG frames_to_capture,
OUT PVOID *backtrace,
OUT PULONG backtrace_hash);
// Load the function we need at static init time, where we don't have
// to worry about someone else holding the loader's lock.
static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
(RtlCaptureStackBackTrace_Function*)
GetProcAddress(GetModuleHandleA("ntdll.dll"), "RtlCaptureStackBackTrace");
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
int n = 0;
if (!RtlCaptureStackBackTrace_fn) {
// can't find a stacktrace with no function to call
} else {
n = (int)RtlCaptureStackBackTrace_fn(skip_count + 2, max_depth, result, 0);
}
if (IS_STACK_FRAMES) {
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * n);
}
if (min_dropped_frames != nullptr) {
// Not implemented.
*min_dropped_frames = 0;
}
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_

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// Copyright 2017 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
//
// http://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.
//
// Produce stack trace
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
#include <ucontext.h> // for ucontext_t
#endif
#if !defined(_WIN32)
#include <unistd.h>
#endif
#include <cassert>
#include <cstdint>
#include "absl/base/macros.h"
#include "absl/base/port.h"
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
#include "absl/debugging/stacktrace.h"
#include "absl/base/internal/raw_logging.h"
#if defined(__linux__) && defined(__i386__)
// Count "push %reg" instructions in VDSO __kernel_vsyscall(),
// preceeding "syscall" or "sysenter".
// If __kernel_vsyscall uses frame pointer, answer 0.
//
// kMaxBytes tells how many instruction bytes of __kernel_vsyscall
// to analyze before giving up. Up to kMaxBytes+1 bytes of
// instructions could be accessed.
//
// Here are known __kernel_vsyscall instruction sequences:
//
// SYSENTER (linux-2.6.26/arch/x86/vdso/vdso32/sysenter.S).
// Used on Intel.
// 0xffffe400 <__kernel_vsyscall+0>: push %ecx
// 0xffffe401 <__kernel_vsyscall+1>: push %edx
// 0xffffe402 <__kernel_vsyscall+2>: push %ebp
// 0xffffe403 <__kernel_vsyscall+3>: mov %esp,%ebp
// 0xffffe405 <__kernel_vsyscall+5>: sysenter
//
// SYSCALL (see linux-2.6.26/arch/x86/vdso/vdso32/syscall.S).
// Used on AMD.
// 0xffffe400 <__kernel_vsyscall+0>: push %ebp
// 0xffffe401 <__kernel_vsyscall+1>: mov %ecx,%ebp
// 0xffffe403 <__kernel_vsyscall+3>: syscall
//
// The sequence below isn't actually expected in Google fleet,
// here only for completeness. Remove this comment from OSS release.
// i386 (see linux-2.6.26/arch/x86/vdso/vdso32/int80.S)
// 0xffffe400 <__kernel_vsyscall+0>: int $0x80
// 0xffffe401 <__kernel_vsyscall+1>: ret
//
static const int kMaxBytes = 10;
// We use assert()s instead of DCHECK()s -- this is too low level
// for DCHECK().
static int CountPushInstructions(const unsigned char *const addr) {
int result = 0;
for (int i = 0; i < kMaxBytes; ++i) {
if (addr[i] == 0x89) {
// "mov reg,reg"
if (addr[i + 1] == 0xE5) {
// Found "mov %esp,%ebp".
return 0;
}
++i; // Skip register encoding byte.
} else if (addr[i] == 0x0F &&
(addr[i + 1] == 0x34 || addr[i + 1] == 0x05)) {
// Found "sysenter" or "syscall".
return result;
} else if ((addr[i] & 0xF0) == 0x50) {
// Found "push %reg".
++result;
} else if (addr[i] == 0xCD && addr[i + 1] == 0x80) {
// Found "int $0x80"
assert(result == 0);
return 0;
} else {
// Unexpected instruction.
assert(false && "unexpected instruction in __kernel_vsyscall");
return 0;
}
}
// Unexpected: didn't find SYSENTER or SYSCALL in
// [__kernel_vsyscall, __kernel_vsyscall + kMaxBytes) interval.
assert(false && "did not find SYSENTER or SYSCALL in __kernel_vsyscall");
return 0;
}
#endif
// Assume stack frames larger than 100,000 bytes are bogus.
static const int kMaxFrameBytes = 100000;
// Returns the stack frame pointer from signal context, 0 if unknown.
// vuc is a ucontext_t *. We use void* to avoid the use
// of ucontext_t on non-POSIX systems.
static uintptr_t GetFP(const void *vuc) {
#if defined(__linux__)
if (vuc != nullptr) {
auto *uc = reinterpret_cast<const ucontext_t *>(vuc);
#if defined(__i386__)
const auto bp = uc->uc_mcontext.gregs[REG_EBP];
const auto sp = uc->uc_mcontext.gregs[REG_ESP];
#elif defined(__x86_64__)
const auto bp = uc->uc_mcontext.gregs[REG_RBP];
const auto sp = uc->uc_mcontext.gregs[REG_RSP];
#else
const uintptr_t bp = 0;
const uintptr_t sp = 0;
#endif
// Sanity-check that the base pointer is valid. It should be as long as
// SHRINK_WRAP_FRAME_POINTER is not set, but it's possible that some code in
// the process is compiled with --copt=-fomit-frame-pointer or
// --copt=-momit-leaf-frame-pointer.
//
// TODO(bcmills): -momit-leaf-frame-pointer is currently the default
// behavior when building with clang. Talk to the C++ toolchain team about
// fixing that.
if (bp >= sp && bp - sp <= kMaxFrameBytes) return bp;
// If bp isn't a plausible frame pointer, return the stack pointer instead.
// If we're lucky, it points to the start of a stack frame; otherwise, we'll
// get one frame of garbage in the stack trace and fail the sanity check on
// the next iteration.
return sp;
}
#endif
return 0;
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template <bool STRICT_UNWINDING, bool WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void **NextStackFrame(void **old_fp, const void *uc) {
void **new_fp = (void **)*old_fp;
#if defined(__linux__) && defined(__i386__)
if (WITH_CONTEXT && uc != nullptr) {
// How many "push %reg" instructions are there at __kernel_vsyscall?
// This is constant for a given kernel and processor, so compute
// it only once.
static int num_push_instructions = -1; // Sentinel: not computed yet.
// Initialize with sentinel value: __kernel_rt_sigreturn can not possibly
// be there.
static const unsigned char *kernel_rt_sigreturn_address = nullptr;
static const unsigned char *kernel_vsyscall_address = nullptr;
if (num_push_instructions == -1) {
absl::debug_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debug_internal::VDSOSupport::SymbolInfo
rt_sigreturn_symbol_info;
absl::debug_internal::VDSOSupport::SymbolInfo vsyscall_symbol_info;
if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.5", STT_FUNC,
&rt_sigreturn_symbol_info) ||
!vdso.LookupSymbol("__kernel_vsyscall", "LINUX_2.5", STT_FUNC,
&vsyscall_symbol_info) ||
rt_sigreturn_symbol_info.address == nullptr ||
vsyscall_symbol_info.address == nullptr) {
// Unexpected: 32-bit VDSO is present, yet one of the expected
// symbols is missing or null.
assert(false && "VDSO is present, but doesn't have expected symbols");
num_push_instructions = 0;
} else {
kernel_rt_sigreturn_address =
reinterpret_cast<const unsigned char *>(
rt_sigreturn_symbol_info.address);
kernel_vsyscall_address =
reinterpret_cast<const unsigned char *>(
vsyscall_symbol_info.address);
num_push_instructions =
CountPushInstructions(kernel_vsyscall_address);
}
} else {
num_push_instructions = 0;
}
}
if (num_push_instructions != 0 && kernel_rt_sigreturn_address != nullptr &&
old_fp[1] == kernel_rt_sigreturn_address) {
const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
// This kernel does not use frame pointer in its VDSO code,
// and so %ebp is not suitable for unwinding.
void **const reg_ebp =
reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_EBP]);
const unsigned char *const reg_eip =
reinterpret_cast<unsigned char *>(ucv->uc_mcontext.gregs[REG_EIP]);
if (new_fp == reg_ebp && kernel_vsyscall_address <= reg_eip &&
reg_eip - kernel_vsyscall_address < kMaxBytes) {
// We "stepped up" to __kernel_vsyscall, but %ebp is not usable.
// Restore from 'ucv' instead.
void **const reg_esp =
reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_ESP]);
// Check that alleged %esp is not null and is reasonably aligned.
if (reg_esp &&
((uintptr_t)reg_esp & (sizeof(reg_esp) - 1)) == 0) {
// Check that alleged %esp is actually readable. This is to prevent
// "double fault" in case we hit the first fault due to e.g. stack
// corruption.
void *const reg_esp2 = reg_esp[num_push_instructions - 1];
if (absl::debug_internal::AddressIsReadable(reg_esp2)) {
// Alleged %esp is readable, use it for further unwinding.
new_fp = reinterpret_cast<void **>(reg_esp2);
}
}
}
}
}
#endif
const uintptr_t old_fp_u = reinterpret_cast<uintptr_t>(old_fp);
const uintptr_t new_fp_u = reinterpret_cast<uintptr_t>(new_fp);
// Check that the transition from frame pointer old_fp to frame
// pointer new_fp isn't clearly bogus. Skip the checks if new_fp
// matches the signal context, so that we don't skip out early when
// using an alternate signal stack.
//
// TODO(bcmills): The GetFP call should be completely unnecessary when
// SHRINK_WRAP_FRAME_POINTER is set (because we should be back in the thread's
// stack by this point), but it is empirically still needed (e.g. when the
// stack includes a call to abort). unw_get_reg returns UNW_EBADREG for some
// frames. Figure out why GetValidFrameAddr and/or libunwind isn't doing what
// it's supposed to.
if (STRICT_UNWINDING &&
(!WITH_CONTEXT || uc == nullptr || new_fp_u != GetFP(uc))) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_fp_u <= old_fp_u) return nullptr;
if (new_fp_u - old_fp_u > kMaxFrameBytes) return nullptr;
} else {
if (new_fp == nullptr) return nullptr; // skip AddressIsReadable() below
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_fp == old_fp) return nullptr;
}
if (new_fp_u & (sizeof(void *) - 1)) return nullptr;
#ifdef __i386__
// On 32-bit machines, the stack pointer can be very close to
// 0xffffffff, so we explicitly check for a pointer into the
// last two pages in the address space
if (new_fp_u >= 0xffffe000) return nullptr;
#endif
#if !defined(_WIN32)
if (!STRICT_UNWINDING) {
// Lax sanity checks cause a crash in 32-bit tcmalloc/crash_reason_test
// on AMD-based machines with VDSO-enabled kernels.
// Make an extra sanity check to insure new_fp is readable.
// Note: NextStackFrame<false>() is only called while the program
// is already on its last leg, so it's ok to be slow here.
if (!absl::debug_internal::AddressIsReadable(new_fp)) {
return nullptr;
}
}
#endif
return new_fp;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
ABSL_ATTRIBUTE_NOINLINE
static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
int n = 0;
void **fp = reinterpret_cast<void **>(__builtin_frame_address(0));
while (fp && n < max_depth) {
if (*(fp + 1) == reinterpret_cast<void *>(0)) {
// In 64-bit code, we often see a frame that
// points to itself and has a return address of 0.
break;
}
void **next_fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = *(fp + 1);
if (IS_STACK_FRAMES) {
if (next_fp > fp) {
sizes[n] = (uintptr_t)next_fp - (uintptr_t)fp;
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
fp = next_fp;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 1000;
int j = 0;
for (; fp != nullptr && j < kMaxUnwind; j++) {
fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp);
}
*min_dropped_frames = j;
}
return n;
}
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_

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// Copyright 2017 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
//
// http://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.
// Allow dynamic symbol lookup in the kernel VDSO page.
//
// VDSOSupport -- a class representing kernel VDSO (if present).
#include "absl/debugging/internal/vdso_support.h"
#ifdef ABSL_HAVE_VDSO_SUPPORT // defined in vdso_support.h
#include <fcntl.h>
#include <sys/syscall.h>
#include <unistd.h>
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/port.h"
#ifndef AT_SYSINFO_EHDR
#define AT_SYSINFO_EHDR 33 // for crosstoolv10
#endif
namespace absl {
namespace debug_internal {
std::atomic<const void *> VDSOSupport::vdso_base_(
debug_internal::ElfMemImage::kInvalidBase);
std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(&InitAndGetCPU);
VDSOSupport::VDSOSupport()
// If vdso_base_ is still set to kInvalidBase, we got here
// before VDSOSupport::Init has been called. Call it now.
: image_(vdso_base_.load(std::memory_order_relaxed) ==
debug_internal::ElfMemImage::kInvalidBase
? Init()
: vdso_base_.load(std::memory_order_relaxed)) {}
// NOTE: we can't use GoogleOnceInit() below, because we can be
// called by tcmalloc, and none of the *once* stuff may be functional yet.
//
// In addition, we hope that the VDSOSupportHelper constructor
// causes this code to run before there are any threads, and before
// InitGoogle() has executed any chroot or setuid calls.
//
// Finally, even if there is a race here, it is harmless, because
// the operation should be idempotent.
const void *VDSOSupport::Init() {
if (vdso_base_.load(std::memory_order_relaxed) ==
debug_internal::ElfMemImage::kInvalidBase) {
{
// Valgrind zaps AT_SYSINFO_EHDR and friends from the auxv[]
// on stack, and so glibc works as if VDSO was not present.
// But going directly to kernel via /proc/self/auxv below bypasses
// Valgrind zapping. So we check for Valgrind separately.
if (RunningOnValgrind()) {
vdso_base_.store(nullptr, std::memory_order_relaxed);
getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
return nullptr;
}
int fd = open("/proc/self/auxv", O_RDONLY);
if (fd == -1) {
// Kernel too old to have a VDSO.
vdso_base_.store(nullptr, std::memory_order_relaxed);
getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
return nullptr;
}
ElfW(auxv_t) aux;
while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
if (aux.a_type == AT_SYSINFO_EHDR) {
vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
std::memory_order_relaxed);
break;
}
}
close(fd);
}
if (vdso_base_.load(std::memory_order_relaxed) ==
debug_internal::ElfMemImage::kInvalidBase) {
// Didn't find AT_SYSINFO_EHDR in auxv[].
vdso_base_.store(nullptr, std::memory_order_relaxed);
}
}
GetCpuFn fn = &GetCPUViaSyscall; // default if VDSO not present.
if (vdso_base_.load(std::memory_order_relaxed)) {
VDSOSupport vdso;
SymbolInfo info;
if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
fn = reinterpret_cast<GetCpuFn>(const_cast<void *>(info.address));
}
}
// Subtle: this code runs outside of any locks; prevent compiler
// from assigning to getcpu_fn_ more than once.
getcpu_fn_.store(fn, std::memory_order_relaxed);
return vdso_base_.load(std::memory_order_relaxed);
}
const void *VDSOSupport::SetBase(const void *base) {
ABSL_RAW_CHECK(base != debug_internal::ElfMemImage::kInvalidBase,
"internal error");
const void *old_base = vdso_base_.load(std::memory_order_relaxed);
vdso_base_.store(base, std::memory_order_relaxed);
image_.Init(base);
// Also reset getcpu_fn_, so GetCPU could be tested with simulated VDSO.
getcpu_fn_.store(&InitAndGetCPU, std::memory_order_relaxed);
return old_base;
}
bool VDSOSupport::LookupSymbol(const char *name,
const char *version,
int type,
SymbolInfo *info) const {
return image_.LookupSymbol(name, version, type, info);
}
bool VDSOSupport::LookupSymbolByAddress(const void *address,
SymbolInfo *info_out) const {
return image_.LookupSymbolByAddress(address, info_out);
}
// NOLINT on 'long' because this routine mimics kernel api.
long VDSOSupport::GetCPUViaSyscall(unsigned *cpu, // NOLINT(runtime/int)
void *, void *) {
#ifdef SYS_getcpu
return syscall(SYS_getcpu, cpu, nullptr, nullptr);
#else
// x86_64 never implemented sys_getcpu(), except as a VDSO call.
errno = ENOSYS;
return -1;
#endif
}
// Use fast __vdso_getcpu if available.
long VDSOSupport::InitAndGetCPU(unsigned *cpu, // NOLINT(runtime/int)
void *x, void *y) {
Init();
GetCpuFn fn = getcpu_fn_.load(std::memory_order_relaxed);
ABSL_RAW_CHECK(fn != &InitAndGetCPU, "Init() did not set getcpu_fn_");
return (*fn)(cpu, x, y);
}
// This function must be very fast, and may be called from very
// low level (e.g. tcmalloc). Hence I avoid things like
// GoogleOnceInit() and ::operator new.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY
int GetCPU() {
unsigned cpu;
int ret_code = (*VDSOSupport::getcpu_fn_)(&cpu, nullptr, nullptr);
return ret_code == 0 ? cpu : ret_code;
}
// We need to make sure VDSOSupport::Init() is called before
// InitGoogle() does any setuid or chroot calls. If VDSOSupport
// is used in any global constructor, this will happen, since
// VDSOSupport's constructor calls Init. But if not, we need to
// ensure it here, with a global constructor of our own. This
// is an allowed exception to the normal rule against non-trivial
// global constructors.
static class VDSOInitHelper {
public:
VDSOInitHelper() { VDSOSupport::Init(); }
} vdso_init_helper;
} // namespace debug_internal
} // namespace absl
#endif // ABSL_HAVE_VDSO_SUPPORT

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//
// Copyright 2017 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
//
// http://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.
//
// Allow dynamic symbol lookup in the kernel VDSO page.
//
// VDSO stands for "Virtual Dynamic Shared Object" -- a page of
// executable code, which looks like a shared library, but doesn't
// necessarily exist anywhere on disk, and which gets mmap()ed into
// every process by kernels which support VDSO, such as 2.6.x for 32-bit
// executables, and 2.6.24 and above for 64-bit executables.
//
// More details could be found here:
// http://www.trilithium.com/johan/2005/08/linux-gate/
//
// VDSOSupport -- a class representing kernel VDSO (if present).
//
// Example usage:
// VDSOSupport vdso;
// VDSOSupport::SymbolInfo info;
// typedef (*FN)(unsigned *, void *, void *);
// FN fn = nullptr;
// if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
// fn = reinterpret_cast<FN>(info.address);
// }
#ifndef ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
#define ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
#include <atomic>
#include "absl/debugging/internal/elf_mem_image.h"
#ifdef ABSL_HAVE_ELF_MEM_IMAGE
#ifdef ABSL_HAVE_VDSO_SUPPORT
#error ABSL_HAVE_VDSO_SUPPORT cannot be directly set
#else
#define ABSL_HAVE_VDSO_SUPPORT 1
#endif
namespace absl {
namespace debug_internal {
// NOTE: this class may be used from within tcmalloc, and can not
// use any memory allocation routines.
class VDSOSupport {
public:
VDSOSupport();
typedef ElfMemImage::SymbolInfo SymbolInfo;
typedef ElfMemImage::SymbolIterator SymbolIterator;
// On PowerPC64 VDSO symbols can either be of type STT_FUNC or STT_NOTYPE
// depending on how the kernel is built. The kernel is normally built with
// STT_NOTYPE type VDSO symbols. Let's make things simpler first by using a
// compile-time constant.
#ifdef __powerpc64__
enum { kVDSOSymbolType = STT_NOTYPE };
#else
enum { kVDSOSymbolType = STT_FUNC };
#endif
// Answers whether we have a vdso at all.
bool IsPresent() const { return image_.IsPresent(); }
// Allow to iterate over all VDSO symbols.
SymbolIterator begin() const { return image_.begin(); }
SymbolIterator end() const { return image_.end(); }
// Look up versioned dynamic symbol in the kernel VDSO.
// Returns false if VDSO is not present, or doesn't contain given
// symbol/version/type combination.
// If info_out != nullptr, additional details are filled in.
bool LookupSymbol(const char *name, const char *version,
int symbol_type, SymbolInfo *info_out) const;
// Find info about symbol (if any) which overlaps given address.
// Returns true if symbol was found; false if VDSO isn't present
// or doesn't have a symbol overlapping given address.
// If info_out != nullptr, additional details are filled in.
bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
// Used only for testing. Replace real VDSO base with a mock.
// Returns previous value of vdso_base_. After you are done testing,
// you are expected to call SetBase() with previous value, in order to
// reset state to the way it was.
const void *SetBase(const void *s);
// Computes vdso_base_ and returns it. Should be called as early as
// possible; before any thread creation, chroot or setuid.
static const void *Init();
private:
// image_ represents VDSO ELF image in memory.
// image_.ehdr_ == nullptr implies there is no VDSO.
ElfMemImage image_;
// Cached value of auxv AT_SYSINFO_EHDR, computed once.
// This is a tri-state:
// kInvalidBase => value hasn't been determined yet.
// 0 => there is no VDSO.
// else => vma of VDSO Elf{32,64}_Ehdr.
//
// When testing with mock VDSO, low bit is set.
// The low bit is always available because vdso_base_ is
// page-aligned.
static std::atomic<const void *> vdso_base_;
// NOLINT on 'long' because these routines mimic kernel api.
// The 'cache' parameter may be used by some versions of the kernel,
// and should be nullptr or point to a static buffer containing at
// least two 'long's.
static long InitAndGetCPU(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
static long GetCPUViaSyscall(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
typedef long (*GetCpuFn)(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
// This function pointer may point to InitAndGetCPU,
// GetCPUViaSyscall, or __vdso_getcpu at different stages of initialization.
static std::atomic<GetCpuFn> getcpu_fn_;
friend int GetCPU(void); // Needs access to getcpu_fn_.
VDSOSupport(const VDSOSupport&) = delete;
VDSOSupport& operator=(const VDSOSupport&) = delete;
};
// Same as sched_getcpu() on later glibc versions.
// Return current CPU, using (fast) __vdso_getcpu@LINUX_2.6 if present,
// otherwise use syscall(SYS_getcpu,...).
// May return -1 with errno == ENOSYS if the kernel doesn't
// support SYS_getcpu.
int GetCPU();
} // namespace debug_internal
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE
#endif // ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_

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// Wrappers around lsan_interface functions.
// When lsan is not linked in, these functions are not available,
// therefore Abseil code which depends on these functions is conditioned on the
// definition of LEAK_SANITIZER.
#include "absl/debugging/leak_check.h"
#ifndef LEAK_SANITIZER
namespace absl {
bool HaveLeakSanitizer() { return false; }
void DoIgnoreLeak(const void*) { }
void RegisterLivePointers(const void*, size_t) { }
void UnRegisterLivePointers(const void*, size_t) { }
LeakCheckDisabler::LeakCheckDisabler() { }
LeakCheckDisabler::~LeakCheckDisabler() { }
} // namespace absl
#else
#include <sanitizer/lsan_interface.h>
namespace absl {
bool HaveLeakSanitizer() { return true; }
void DoIgnoreLeak(const void* ptr) { __lsan_ignore_object(ptr); }
void RegisterLivePointers(const void* ptr, size_t size) {
__lsan_register_root_region(ptr, size);
}
void UnRegisterLivePointers(const void* ptr, size_t size) {
__lsan_unregister_root_region(ptr, size);
}
LeakCheckDisabler::LeakCheckDisabler() { __lsan_disable(); }
LeakCheckDisabler::~LeakCheckDisabler() { __lsan_enable(); }
} // namespace absl
#endif // LEAK_SANITIZER

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//
// Copyright 2017 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
//
// http://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.
//
// -----------------------------------------------------------------------------
// File: leak_check.h
// -----------------------------------------------------------------------------
//
// This package contains functions that affect leak checking behavior within
// targets built with the LeakSanitizer (LSan), a memory leak detector that is
// integrated within the AddressSanitizer (ASan) as an additional component, or
// which can be used standalone. LSan and ASan are included or can be provided
// as additional components for most compilers such as Clang, gcc and MSVC.
// Note: this leak checking API is not yet supported in MSVC.
// Leak checking is enabled by default in all ASan builds.
//
// See https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer
//
// -----------------------------------------------------------------------------
#ifndef ABSL_DEBUGGING_LEAK_CHECK_H_
#define ABSL_DEBUGGING_LEAK_CHECK_H_
#include <cstddef>
namespace absl {
// HaveLeakSanitizer()
//
// Returns true if a leak-checking sanitizer (either ASan or standalone LSan) is
// currently built into this target.
bool HaveLeakSanitizer();
// DoIgnoreLeak()
//
// Implements `IgnoreLeak()` below. This function should usually
// not be called directly; calling `IgnoreLeak()` is preferred.
void DoIgnoreLeak(const void* ptr);
// IgnoreLeak()
//
// Instruct the leak sanitizer to ignore leak warnings on the object referenced
// by the passed pointer, as well as all heap objects transitively referenced
// by it. The passed object pointer can point to either the beginning of the
// object or anywhere within it.
//
// Example:
//
// static T* obj = IgnoreLeak(new T(...));
//
// If the passed `ptr` does not point to an actively allocated object at the
// time `IgnoreLeak()` is called, the call is a no-op; if it is actively
// allocated, the object must not get deallocated later.
//
template <typename T>
T* IgnoreLeak(T* ptr) {
DoIgnoreLeak(ptr);
return ptr;
}
// LeakCheckDisabler
//
// This helper class indicates that any heap allocations done in the code block
// covered by the scoped object, which should be allocated on the stack, will
// not be reported as leaks. Leak check disabling will occur within the code
// block and any nested function calls within the code block.
//
// Example:
//
// void Foo() {
// LeakCheckDisabler disabler;
// ... code that allocates objects whose leaks should be ignored ...
// }
//
// REQUIRES: Destructor runs in same thread as constructor
class LeakCheckDisabler {
public:
LeakCheckDisabler();
LeakCheckDisabler(const LeakCheckDisabler&) = delete;
LeakCheckDisabler& operator=(const LeakCheckDisabler&) = delete;
~LeakCheckDisabler();
};
// RegisterLivePointers()
//
// Registers `ptr[0,size-1]` as pointers to memory that is still actively being
// referenced and for which leak checking should be ignored. This function is
// useful if you store pointers in mapped memory, for memory ranges that we know
// are correct but for which normal analysis would flag as leaked code.
void RegisterLivePointers(const void* ptr, size_t size);
// UnRegisterLivePointers()
//
// Deregisters the pointers previously marked as active in
// `RegisterLivePointers()`, enabling leak checking of those pointers.
void UnRegisterLivePointers(const void* ptr, size_t size);
} // namespace absl
#endif // ABSL_DEBUGGING_LEAK_CHECK_H_

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// Copyright 2017 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
//
// http://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.
// Disable LeakSanitizer when this file is linked in.
// This function overrides __lsan_is_turned_off from sanitizer/lsan_interface.h
extern "C" int __lsan_is_turned_off();
extern "C" int __lsan_is_turned_off() {
return 1;
}

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// Copyright 2017 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
//
// http://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 <memory>
#include "gtest/gtest.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/debugging/leak_check.h"
namespace {
TEST(LeakCheckTest, LeakMemory) {
// This test is expected to cause lsan failures on program exit. Therefore the
// test will be run only by leak_check_test.sh, which will verify a
// failed exit code.
char* foo = strdup("lsan should complain about this leaked string");
ABSL_RAW_LOG(INFO, "Should detect leaked std::string %s", foo);
}
TEST(LeakCheckTest, LeakMemoryAfterDisablerScope) {
// This test is expected to cause lsan failures on program exit. Therefore the
// test will be run only by external_leak_check_test.sh, which will verify a
// failed exit code.
{ absl::LeakCheckDisabler disabler; }
char* foo = strdup("lsan should also complain about this leaked string");
ABSL_RAW_LOG(INFO, "Re-enabled leak detection.Should detect leaked std::string %s",
foo);
}
} // namespace

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// Copyright 2017 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
//
// http://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 <memory>
#include "gtest/gtest.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/debugging/leak_check.h"
namespace {
TEST(LeakCheckTest, DetectLeakSanitizer) {
#ifdef ABSL_EXPECT_LEAK_SANITIZER
EXPECT_TRUE(absl::HaveLeakSanitizer());
#else
EXPECT_FALSE(absl::HaveLeakSanitizer());
#endif
}
TEST(LeakCheckTest, IgnoreLeakSuppressesLeakedMemoryErrors) {
auto foo = absl::IgnoreLeak(new std::string("some ignored leaked string"));
ABSL_RAW_LOG(INFO, "Ignoring leaked std::string %s", foo->c_str());
}
TEST(LeakCheckTest, LeakCheckDisablerIgnoresLeak) {
absl::LeakCheckDisabler disabler;
auto foo = new std::string("some std::string leaked while checks are disabled");
ABSL_RAW_LOG(INFO, "Ignoring leaked std::string %s", foo->c_str());
}
} // namespace

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// Copyright 2017 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
//
// http://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.
// Produce stack trace.
//
// There are three different ways we can try to get the stack trace:
//
// 1) Our hand-coded stack-unwinder. This depends on a certain stack
// layout, which is used by gcc (and those systems using a
// gcc-compatible ABI) on x86 systems, at least since gcc 2.95.
// It uses the frame pointer to do its work.
//
// 2) The libunwind library. This is still in development, and as a
// separate library adds a new dependency, but doesn't need a frame
// pointer. It also doesn't call malloc.
//
// 3) The gdb unwinder -- also the one used by the c++ exception code.
// It's obviously well-tested, but has a fatal flaw: it can call
// malloc() from the unwinder. This is a problem because we're
// trying to use the unwinder to instrument malloc().
//
// Note: if you add a new implementation here, make sure it works
// correctly when absl::GetStackTrace() is called with max_depth == 0.
// Some code may do that.
#include "absl/debugging/stacktrace.h"
#include <atomic>
#include "absl/base/port.h"
#include "absl/debugging/internal/stacktrace_config.h"
#if defined(ABSL_STACKTRACE_INL_HEADER)
#include ABSL_STACKTRACE_INL_HEADER
#else
# error Cannot calculate stack trace: will need to write for your environment
# include "absl/debugging/internal/stacktrace_x86-inl.inc"
# include "absl/debugging/internal/stacktrace_win32-inl.inc"
# include "absl/debugging/internal/stacktrace_unimplemented-inl.inc"
# include "absl/debugging/internal/stacktrace_libunwind-inl.inc"
# include "absl/debugging/internal/stacktrace_generic-inl.inc"
# include "absl/debugging/internal/stacktrace_powerpc-inl.inc"
# include "absl/debugging/internal/stacktrace_arm-inl.inc"
# include "absl/debugging/internal/stacktrace_aarch64-inl.inc"
#endif
namespace absl {
namespace {
typedef int (*Unwinder)(void**, int*, int, int, const void*, int*);
std::atomic<Unwinder> custom;
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_ALWAYS_INLINE inline int Unwind(void** result, int* sizes,
int max_depth, int skip_count,
const void* uc,
int* min_dropped_frames) {
Unwinder f = &UnwindImpl<IS_STACK_FRAMES, IS_WITH_CONTEXT>;
Unwinder g = custom.load(std::memory_order_acquire);
if (g != nullptr) f = g;
// Add 1 to skip count for the unwinder function itself
int size = (*f)(result, sizes, max_depth, skip_count + 1, uc,
min_dropped_frames);
// To disable tail call to (*f)(...)
ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
return size;
}
} // anonymous namespace
int GetStackFrames(void** result, int* sizes, int max_depth, int skip_count) {
return Unwind<true, false>(result, sizes, max_depth, skip_count, nullptr,
nullptr);
}
int GetStackFramesWithContext(void** result, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames) {
return Unwind<true, true>(result, sizes, max_depth, skip_count, uc,
min_dropped_frames);
}
int GetStackTrace(void** result, int max_depth, int skip_count) {
return Unwind<false, false>(result, nullptr, max_depth, skip_count, nullptr,
nullptr);
}
int GetStackTraceWithContext(void** result, int max_depth, int skip_count,
const void* uc, int* min_dropped_frames) {
return Unwind<false, true>(result, nullptr, max_depth, skip_count, uc,
min_dropped_frames);
}
void SetStackUnwinder(Unwinder w) {
custom.store(w, std::memory_order_release);
}
int DefaultStackUnwinder(void** pcs, int* sizes, int depth, int skip,
const void* uc, int* min_dropped_frames) {
skip++; // For this function
Unwinder f = nullptr;
if (sizes == nullptr) {
if (uc == nullptr) {
f = &UnwindImpl<false, false>;
} else {
f = &UnwindImpl<false, true>;
}
} else {
if (uc == nullptr) {
f = &UnwindImpl<true, false>;
} else {
f = &UnwindImpl<true, true>;
}
}
volatile int x = 0;
int n = (*f)(pcs, sizes, depth, skip, uc, min_dropped_frames);
x = 1; (void) x; // To disable tail call to (*f)(...)
return n;
}
} // namespace absl

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//
// Copyright 2017 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
//
// http://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.
//
// Routines to extract the current stack trace. These functions are
// thread-safe and async-signal-safe.
// Note that stack trace functionality is platform dependent and requires
// additional support from the compiler/build system in many cases. (That is,
// this generally only works on platforms/builds that have been specifically
// configured to support it.)
#ifndef ABSL_DEBUGGING_STACKTRACE_H_
#define ABSL_DEBUGGING_STACKTRACE_H_
namespace absl {
// Skips the most recent "skip_count" stack frames (also skips the
// frame generated for the "absl::GetStackFrames" routine itself), and then
// records the pc values for up to the next "max_depth" frames in
// "result", and the corresponding stack frame sizes in "sizes".
// Returns the number of values recorded in "result"/"sizes".
//
// Example:
// main() { foo(); }
// foo() { bar(); }
// bar() {
// void* result[10];
// int sizes[10];
// int depth = absl::GetStackFrames(result, sizes, 10, 1);
// }
//
// The absl::GetStackFrames call will skip the frame for "bar". It will
// return 2 and will produce pc values that map to the following
// procedures:
// result[0] foo
// result[1] main
// (Actually, there may be a few more entries after "main" to account for
// startup procedures.)
// And corresponding stack frame sizes will also be recorded:
// sizes[0] 16
// sizes[1] 16
// (Stack frame sizes of 16 above are just for illustration purposes.)
// Stack frame sizes of 0 or less indicate that those frame sizes couldn't
// be identified.
//
// This routine may return fewer stack frame entries than are
// available. Also note that "result" and "sizes" must both be non-null.
extern int GetStackFrames(void** result, int* sizes, int max_depth,
int skip_count);
// Same as above, but to be used from a signal handler. The "uc" parameter
// should be the pointer to ucontext_t which was passed as the 3rd parameter
// to sa_sigaction signal handler. It may help the unwinder to get a
// better stack trace under certain conditions. The "uc" may safely be null.
//
// If min_dropped_frames is not null, stores in *min_dropped_frames a
// lower bound on the number of dropped stack frames. The stored value is
// guaranteed to be >= 0. The number of real stack frames is guaranteed to
// be >= skip_count + max_depth + *min_dropped_frames.
extern int GetStackFramesWithContext(void** result, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
// This is similar to the absl::GetStackFrames routine, except that it returns
// the stack trace only, and not the stack frame sizes as well.
// Example:
// main() { foo(); }
// foo() { bar(); }
// bar() {
// void* result[10];
// int depth = absl::GetStackTrace(result, 10, 1);
// }
//
// This produces:
// result[0] foo
// result[1] main
// .... ...
//
// "result" must not be null.
extern int GetStackTrace(void** result, int max_depth, int skip_count);
// Same as above, but to be used from a signal handler. The "uc" parameter
// should be the pointer to ucontext_t which was passed as the 3rd parameter
// to sa_sigaction signal handler. It may help the unwinder to get a
// better stack trace under certain conditions. The "uc" may safely be null.
//
// If min_dropped_frames is not null, stores in *min_dropped_frames a
// lower bound on the number of dropped stack frames. The stored value is
// guaranteed to be >= 0. The number of real stack frames is guaranteed to
// be >= skip_count + max_depth + *min_dropped_frames.
extern int GetStackTraceWithContext(void** result, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
// Call this to provide a custom function for unwinding stack frames
// that will be used every time someone invokes one of the static
// GetStack{Frames,Trace}{,WithContext}() functions above.
//
// The arguments passed to the unwinder function will match the
// arguments passed to absl::GetStackFramesWithContext() except that sizes
// will be non-null iff the caller is interested in frame sizes.
//
// If unwinder is null, we revert to the default stack-tracing behavior.
//
// ****************************************************************
// WARNINGS
//
// absl::SetStackUnwinder is not suitable for general purpose use. It is
// provided for custom runtimes.
// Some things to watch out for when calling absl::SetStackUnwinder:
//
// (a) The unwinder may be called from within signal handlers and
// therefore must be async-signal-safe.
//
// (b) Even after a custom stack unwinder has been unregistered, other
// threads may still be in the process of using that unwinder.
// Therefore do not clean up any state that may be needed by an old
// unwinder.
// ****************************************************************
extern void SetStackUnwinder(int (*unwinder)(void** pcs, int* sizes,
int max_depth, int skip_count,
const void* uc,
int* min_dropped_frames));
// Function that exposes built-in stack-unwinding behavior, ignoring
// any calls to absl::SetStackUnwinder().
//
// pcs must NOT be null.
//
// sizes may be null.
// uc may be null.
// min_dropped_frames may be null.
//
// The semantics are the same as the corresponding GetStack*() function in the
// case where absl::SetStackUnwinder() was never called. Equivalents are:
//
// null sizes | non-nullptr sizes
// |==========================================================|
// null uc | GetStackTrace() | GetStackFrames() |
// non-null uc | GetStackTraceWithContext() | GetStackFramesWithContext() |
// |==========================================================|
extern int DefaultStackUnwinder(void** pcs, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
} // namespace absl
#endif // ABSL_DEBUGGING_STACKTRACE_H_