// Copyright (c) 2010, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// This code writes out minidump files:
// http://msdn.microsoft.com/en-us/library/ms680378(VS.85,loband).aspx
//
// Minidumps are a Microsoft format which Breakpad uses for recording crash
// dumps. This code has to run in a compromised environment (the address space
// may have received SIGSEGV), thus the following rules apply:
// * You may not enter the dynamic linker. This means that we cannot call
// any symbols in a shared library (inc libc). Because of this we replace
// libc functions in linux_libc_support.h.
// * You may not call syscalls via the libc wrappers. This rule is a subset
// of the first rule but it bears repeating. We have direct wrappers
// around the system calls in linux_syscall_support.h.
// * You may not malloc. There's an alternative allocator in memory.h and
// a canonical instance in the LinuxDumper object. We use the placement
// new form to allocate objects and we don't delete them.
#include "client/linux/handler/minidump_descriptor.h"
#include "client/linux/minidump_writer/minidump_writer.h"
#include "client/minidump_file_writer-inl.h"
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <link.h>
#include <stdio.h>
#if defined(__ANDROID__)
#include <sys/system_properties.h>
#endif
#include <sys/types.h>
#include <sys/ucontext.h>
#include <sys/user.h>
#include <sys/utsname.h>
#include <time.h>
#include <unistd.h>
#include <algorithm>
#include "client/linux/dump_writer_common/seccomp_unwinder.h"
#include "client/linux/dump_writer_common/thread_info.h"
#include "client/linux/dump_writer_common/ucontext_reader.h"
#include "client/linux/handler/exception_handler.h"
#include "client/linux/minidump_writer/cpu_set.h"
#include "client/linux/minidump_writer/line_reader.h"
#include "client/linux/minidump_writer/linux_dumper.h"
#include "client/linux/minidump_writer/linux_ptrace_dumper.h"
#include "client/linux/minidump_writer/proc_cpuinfo_reader.h"
#include "client/minidump_file_writer.h"
#include "common/linux/linux_libc_support.h"
#include "common/minidump_type_helper.h"
#include "google_breakpad/common/minidump_format.h"
#include "third_party/lss/linux_syscall_support.h"
namespace {
using google_breakpad::AppMemoryList;
using google_breakpad::ExceptionHandler;
using google_breakpad::CpuSet;
using google_breakpad::LineReader;
using google_breakpad::LinuxDumper;
using google_breakpad::LinuxPtraceDumper;
using google_breakpad::MDTypeHelper;
using google_breakpad::MappingEntry;
using google_breakpad::MappingInfo;
using google_breakpad::MappingList;
using google_breakpad::MinidumpFileWriter;
using google_breakpad::PageAllocator;
using google_breakpad::ProcCpuInfoReader;
using google_breakpad::RawContextCPU;
using google_breakpad::SeccompUnwinder;
using google_breakpad::ThreadInfo;
using google_breakpad::TypedMDRVA;
using google_breakpad::UContextReader;
using google_breakpad::UntypedMDRVA;
using google_breakpad::wasteful_vector;
typedef MDTypeHelper<sizeof(void*)>::MDRawDebug MDRawDebug;
typedef MDTypeHelper<sizeof(void*)>::MDRawLinkMap MDRawLinkMap;
class MinidumpWriter {
public:
// The following kLimit* constants are for when minidump_size_limit_ is set
// and the minidump size might exceed it.
//
// Estimate for how big each thread's stack will be (in bytes).
static const unsigned kLimitAverageThreadStackLength = 8 * 1024;
// Number of threads whose stack size we don't want to limit. These base
// threads will simply be the first N threads returned by the dumper (although
// the crashing thread will never be limited). Threads beyond this count are
// the extra threads.
static const unsigned kLimitBaseThreadCount = 20;
// Maximum stack size to dump for any extra thread (in bytes).
static const unsigned kLimitMaxExtraThreadStackLen = 2 * 1024;
// Make sure this number of additional bytes can fit in the minidump
// (exclude the stack data).
static const unsigned kLimitMinidumpFudgeFactor = 64 * 1024;
MinidumpWriter(const char* minidump_path,
int minidump_fd,
const ExceptionHandler::CrashContext* context,
const MappingList& mappings,
const AppMemoryList& appmem,
LinuxDumper* dumper)
: fd_(minidump_fd),
path_(minidump_path),
ucontext_(context ? &context->context : NULL),
#if !defined(__ARM_EABI__) && !defined(__mips__)
float_state_(context ? &context->float_state : NULL),
#endif
dumper_(dumper),
minidump_size_limit_(-1),
memory_blocks_(dumper_->allocator()),
mapping_list_(mappings),
app_memory_list_(appmem) {
// Assert there should be either a valid fd or a valid path, not both.
assert(fd_ != -1 || minidump_path);
assert(fd_ == -1 || !minidump_path);
}
bool Init() {
if (!dumper_->Init())
return false;
if (fd_ != -1)
minidump_writer_.SetFile(fd_);
else if (!minidump_writer_.Open(path_))
return false;
return dumper_->ThreadsSuspend();
}
~MinidumpWriter() {
// Don't close the file descriptor when it's been provided explicitly.
// Callers might still need to use it.
if (fd_ == -1)
minidump_writer_.Close();
dumper_->ThreadsResume();
}
bool Dump() {
// A minidump file contains a number of tagged streams. This is the number
// of stream which we write.
unsigned kNumWriters = 13;
TypedMDRVA<MDRawHeader> header(&minidump_writer_);
TypedMDRVA<MDRawDirectory> dir(&minidump_writer_);
if (!header.Allocate())
return false;
if (!dir.AllocateArray(kNumWriters))
return false;
my_memset(header.get(), 0, sizeof(MDRawHeader));
header.get()->signature = MD_HEADER_SIGNATURE;
header.get()->version = MD_HEADER_VERSION;
header.get()->time_date_stamp = time(NULL);
header.get()->stream_count = kNumWriters;
header.get()->stream_directory_rva = dir.position();
unsigned dir_index = 0;
MDRawDirectory dirent;
if (!WriteThreadListStream(&dirent))
return false;
dir.CopyIndex(dir_index++, &dirent);
if (!WriteMappings(&dirent))
return false;
dir.CopyIndex(dir_index++, &dirent);
if (!WriteAppMemory())
return false;
if (!WriteMemoryListStream(&dirent))
return false;
dir.CopyIndex(dir_index++, &dirent);
if (!WriteExceptionStream(&dirent))
return false;
dir.CopyIndex(dir_index++, &dirent);
if (!WriteSystemInfoStream(&dirent))
return false;
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_CPU_INFO;
if (!WriteFile(&dirent.location, "/proc/cpuinfo"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_PROC_STATUS;
if (!WriteProcFile(&dirent.location, GetCrashThread(), "status"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_LSB_RELEASE;
if (!WriteFile(&dirent.location, "/etc/lsb-release"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_CMD_LINE;
if (!WriteProcFile(&dirent.location, GetCrashThread(), "cmdline"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_ENVIRON;
if (!WriteProcFile(&dirent.location, GetCrashThread(), "environ"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_AUXV;
if (!WriteProcFile(&dirent.location, GetCrashThread(), "auxv"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_MAPS;
if (!WriteProcFile(&dirent.location, GetCrashThread(), "maps"))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
dirent.stream_type = MD_LINUX_DSO_DEBUG;
if (!WriteDSODebugStream(&dirent))
NullifyDirectoryEntry(&dirent);
dir.CopyIndex(dir_index++, &dirent);
// If you add more directory entries, don't forget to update kNumWriters,
// above.
dumper_->ThreadsResume();
return true;
}
bool FillThreadStack(MDRawThread* thread, uintptr_t stack_pointer,
int max_stack_len, uint8_t** stack_copy) {
*stack_copy = NULL;
const void* stack;
size_t stack_len;
if (dumper_->GetStackInfo(&stack, &stack_len, stack_pointer)) {
UntypedMDRVA memory(&minidump_writer_);
if (max_stack_len >= 0 &&
stack_len > static_cast<unsigned int>(max_stack_len)) {
stack_len = max_stack_len;
}
if (!memory.Allocate(stack_len))
return false;
*stack_copy = reinterpret_cast<uint8_t*>(Alloc(stack_len));
dumper_->CopyFromProcess(*stack_copy, thread->thread_id, stack,
stack_len);
memory.Copy(*stack_copy, stack_len);
thread->stack.start_of_memory_range =
reinterpret_cast<uintptr_t>(stack);
thread->stack.memory = memory.location();
memory_blocks_.push_back(thread->stack);
} else {
thread->stack.start_of_memory_range = stack_pointer;
thread->stack.memory.data_size = 0;
thread->stack.memory.rva = minidump_writer_.position();
}
return true;
}
// Write information about the threads.
bool WriteThreadListStream(MDRawDirectory* dirent) {
const unsigned num_threads = dumper_->threads().size();
TypedMDRVA<uint32_t> list(&minidump_writer_);
if (!list.AllocateObjectAndArray(num_threads, sizeof(MDRawThread)))
return false;
dirent->stream_type = MD_THREAD_LIST_STREAM;
dirent->location = list.location();
*list.get() = num_threads;
// If there's a minidump size limit, check if it might be exceeded. Since
// most of the space is filled with stack data, just check against that.
// If this expects to exceed the limit, set extra_thread_stack_len such
// that any thread beyond the first kLimitBaseThreadCount threads will
// have only kLimitMaxExtraThreadStackLen bytes dumped.
int extra_thread_stack_len = -1; // default to no maximum
if (minidump_size_limit_ >= 0) {
const unsigned estimated_total_stack_size = num_threads *
kLimitAverageThreadStackLength;
const off_t estimated_minidump_size = minidump_writer_.position() +
estimated_total_stack_size + kLimitMinidumpFudgeFactor;
if (estimated_minidump_size > minidump_size_limit_)
extra_thread_stack_len = kLimitMaxExtraThreadStackLen;
}
for (unsigned i = 0; i < num_threads; ++i) {
MDRawThread thread;
my_memset(&thread, 0, sizeof(thread));
thread.thread_id = dumper_->threads()[i];
// We have a different source of information for the crashing thread. If
// we used the actual state of the thread we would find it running in the
// signal handler with the alternative stack, which would be deeply
// unhelpful.
if (static_cast<pid_t>(thread.thread_id) == GetCrashThread() &&
ucontext_ &&
!dumper_->IsPostMortem()) {
uint8_t* stack_copy;
const uintptr_t stack_ptr = UContextReader::GetStackPointer(ucontext_);
if (!FillThreadStack(&thread, stack_ptr, -1, &stack_copy))
return false;
// Copy 256 bytes around crashing instruction pointer to minidump.
const size_t kIPMemorySize = 256;
uint64_t ip = UContextReader::GetInstructionPointer(ucontext_);
// Bound it to the upper and lower bounds of the memory map
// it's contained within. If it's not in mapped memory,
// don't bother trying to write it.
bool ip_is_mapped = false;
MDMemoryDescriptor ip_memory_d;
for (unsigned j = 0; j < dumper_->mappings().size(); ++j) {
const MappingInfo& mapping = *dumper_->mappings()[j];
if (ip >= mapping.start_addr &&
ip < mapping.start_addr + mapping.size) {
ip_is_mapped = true;
// Try to get 128 bytes before and after the IP, but
// settle for whatever's available.
ip_memory_d.start_of_memory_range =
std::max(mapping.start_addr,
uintptr_t(ip - (kIPMemorySize / 2)));
uintptr_t end_of_range =
std::min(uintptr_t(ip + (kIPMemorySize / 2)),
uintptr_t(mapping.start_addr + mapping.size));
ip_memory_d.memory.data_size =
end_of_range - ip_memory_d.start_of_memory_range;
break;
}
}
if (ip_is_mapped) {
UntypedMDRVA ip_memory(&minidump_writer_);
if (!ip_memory.Allocate(ip_memory_d.memory.data_size))
return false;
uint8_t* memory_copy =
reinterpret_cast<uint8_t*>(Alloc(ip_memory_d.memory.data_size));
dumper_->CopyFromProcess(
memory_copy,
thread.thread_id,
reinterpret_cast<void*>(ip_memory_d.start_of_memory_range),
ip_memory_d.memory.data_size);
ip_memory.Copy(memory_copy, ip_memory_d.memory.data_size);
ip_memory_d.memory = ip_memory.location();
memory_blocks_.push_back(ip_memory_d);
}
TypedMDRVA<RawContextCPU> cpu(&minidump_writer_);
if (!cpu.Allocate())
return false;
my_memset(cpu.get(), 0, sizeof(RawContextCPU));
#if !defined(__ARM_EABI__) && !defined(__mips__)
UContextReader::FillCPUContext(cpu.get(), ucontext_, float_state_);
#else
UContextReader::FillCPUContext(cpu.get(), ucontext_);
#endif
if (stack_copy)
SeccompUnwinder::PopSeccompStackFrame(cpu.get(), thread, stack_copy);
thread.thread_context = cpu.location();
crashing_thread_context_ = cpu.location();
} else {
ThreadInfo info;
if (!dumper_->GetThreadInfoByIndex(i, &info))
return false;
uint8_t* stack_copy;
int max_stack_len = -1; // default to no maximum for this thread
if (minidump_size_limit_ >= 0 && i >= kLimitBaseThreadCount)
max_stack_len = extra_thread_stack_len;
if (!FillThreadStack(&thread, info.stack_pointer, max_stack_len,
&stack_copy))
return false;
TypedMDRVA<RawContextCPU> cpu(&minidump_writer_);
if (!cpu.Allocate())
return false;
my_memset(cpu.get(), 0, sizeof(RawContextCPU));
info.FillCPUContext(cpu.get());
if (stack_copy)
SeccompUnwinder::PopSeccompStackFrame(cpu.get(), thread, stack_copy);
thread.thread_context = cpu.location();
if (dumper_->threads()[i] == GetCrashThread()) {
crashing_thread_context_ = cpu.location();
if (!dumper_->IsPostMortem()) {
// This is the crashing thread of a live process, but
// no context was provided, so set the crash address
// while the instruction pointer is already here.
dumper_->set_crash_address(info.GetInstructionPointer());
}
}
}
list.CopyIndexAfterObject(i, &thread, sizeof(thread));
}
return true;
}
// Write application-provided memory regions.
bool WriteAppMemory() {
for (AppMemoryList::const_iterator iter = app_memory_list_.begin();
iter != app_memory_list_.end();
++iter) {
uint8_t* data_copy =
reinterpret_cast<uint8_t*>(dumper_->allocator()->Alloc(iter->length));
dumper_->CopyFromProcess(data_copy, GetCrashThread(), iter->ptr,
iter->length);
UntypedMDRVA memory(&minidump_writer_);
if (!memory.Allocate(iter->length)) {
return false;
}
memory.Copy(data_copy, iter->length);
MDMemoryDescriptor desc;
desc.start_of_memory_range = reinterpret_cast<uintptr_t>(iter->ptr);
desc.memory = memory.location();
memory_blocks_.push_back(desc);
}
return true;
}
static bool ShouldIncludeMapping(const MappingInfo& mapping) {
if (mapping.name[0] == 0 || // only want modules with filenames.
// Only want to include one mapping per shared lib.
// Avoid filtering executable mappings.
(mapping.offset != 0 && !mapping.exec) ||
mapping.size < 4096) { // too small to get a signature for.
return false;
}
return true;
}
// If there is caller-provided information about this mapping
// in the mapping_list_ list, return true. Otherwise, return false.
bool HaveMappingInfo(const MappingInfo& mapping) {
for (MappingList::const_iterator iter = mapping_list_.begin();
iter != mapping_list_.end();
++iter) {
// Ignore any mappings that are wholly contained within
// mappings in the mapping_info_ list.
if (mapping.start_addr >= iter->first.start_addr &&
(mapping.start_addr + mapping.size) <=
(iter->first.start_addr + iter->first.size)) {
return true;
}
}
return false;
}
// Write information about the mappings in effect. Because we are using the
// minidump format, the information about the mappings is pretty limited.
// Because of this, we also include the full, unparsed, /proc/$x/maps file in
// another stream in the file.
bool WriteMappings(MDRawDirectory* dirent) {
const unsigned num_mappings = dumper_->mappings().size();
unsigned num_output_mappings = mapping_list_.size();
for (unsigned i = 0; i < dumper_->mappings().size(); ++i) {
const MappingInfo& mapping = *dumper_->mappings()[i];
if (ShouldIncludeMapping(mapping) && !HaveMappingInfo(mapping))
num_output_mappings++;
}
TypedMDRVA<uint32_t> list(&minidump_writer_);
if (num_output_mappings) {
if (!list.AllocateObjectAndArray(num_output_mappings, MD_MODULE_SIZE))
return false;
} else {
// Still create the module list stream, although it will have zero
// modules.
if (!list.Allocate())
return false;
}
dirent->stream_type = MD_MODULE_LIST_STREAM;
dirent->location = list.location();
*list.get() = num_output_mappings;
// First write all the mappings from the dumper
unsigned int j = 0;
for (unsigned i = 0; i < num_mappings; ++i) {
const MappingInfo& mapping = *dumper_->mappings()[i];
if (!ShouldIncludeMapping(mapping) || HaveMappingInfo(mapping))
continue;
MDRawModule mod;
if (!FillRawModule(mapping, true, i, mod, NULL))
return false;
list.CopyIndexAfterObject(j++, &mod, MD_MODULE_SIZE);
}
// Next write all the mappings provided by the caller
for (MappingList::const_iterator iter = mapping_list_.begin();
iter != mapping_list_.end();
++iter) {
MDRawModule mod;
if (!FillRawModule(iter->first, false, 0, mod, iter->second))
return false;
list.CopyIndexAfterObject(j++, &mod, MD_MODULE_SIZE);
}
return true;
}
// Fill the MDRawModule |mod| with information about the provided
// |mapping|. If |identifier| is non-NULL, use it instead of calculating
// a file ID from the mapping.
bool FillRawModule(const MappingInfo& mapping,
bool member,
unsigned int mapping_id,
MDRawModule& mod,
const uint8_t* identifier) {
my_memset(&mod, 0, MD_MODULE_SIZE);
mod.base_of_image = mapping.start_addr;
mod.size_of_image = mapping.size;
uint8_t cv_buf[MDCVInfoPDB70_minsize + NAME_MAX];
uint8_t* cv_ptr = cv_buf;
const uint32_t cv_signature = MD_CVINFOPDB70_SIGNATURE;
my_memcpy(cv_ptr, &cv_signature, sizeof(cv_signature));
cv_ptr += sizeof(cv_signature);
uint8_t* signature = cv_ptr;
cv_ptr += sizeof(MDGUID);
if (identifier) {
// GUID was provided by caller.
my_memcpy(signature, identifier, sizeof(MDGUID));
} else {
// Note: ElfFileIdentifierForMapping() can manipulate the |mapping.name|.
dumper_->ElfFileIdentifierForMapping(mapping, member,
mapping_id, signature);
}
my_memset(cv_ptr, 0, sizeof(uint32_t)); // Set age to 0 on Linux.
cv_ptr += sizeof(uint32_t);
char file_name[NAME_MAX];
char file_path[NAME_MAX];
LinuxDumper::GetMappingEffectiveNameAndPath(
mapping, file_path, sizeof(file_path), file_name, sizeof(file_name));
const size_t file_name_len = my_strlen(file_name);
UntypedMDRVA cv(&minidump_writer_);
if (!cv.Allocate(MDCVInfoPDB70_minsize + file_name_len + 1))
return false;
// Write pdb_file_name
my_memcpy(cv_ptr, file_name, file_name_len + 1);
cv.Copy(cv_buf, MDCVInfoPDB70_minsize + file_name_len + 1);
mod.cv_record = cv.location();
MDLocationDescriptor ld;
if (!minidump_writer_.WriteString(file_path, my_strlen(file_path), &ld))
return false;
mod.module_name_rva = ld.rva;
return true;
}
bool WriteMemoryListStream(MDRawDirectory* dirent) {
TypedMDRVA<uint32_t> list(&minidump_writer_);
if (memory_blocks_.size()) {
if (!list.AllocateObjectAndArray(memory_blocks_.size(),
sizeof(MDMemoryDescriptor)))
return false;
} else {
// Still create the memory list stream, although it will have zero
// memory blocks.
if (!list.Allocate())
return false;
}
dirent->stream_type = MD_MEMORY_LIST_STREAM;
dirent->location = list.location();
*list.get() = memory_blocks_.size();
for (size_t i = 0; i < memory_blocks_.size(); ++i) {
list.CopyIndexAfterObject(i, &memory_blocks_[i],
sizeof(MDMemoryDescriptor));
}
return true;
}
bool WriteExceptionStream(MDRawDirectory* dirent) {
TypedMDRVA<MDRawExceptionStream> exc(&minidump_writer_);
if (!exc.Allocate())
return false;
my_memset(exc.get(), 0, sizeof(MDRawExceptionStream));
dirent->stream_type = MD_EXCEPTION_STREAM;
dirent->location = exc.location();
exc.get()->thread_id = GetCrashThread();
exc.get()->exception_record.exception_code = dumper_->crash_signal();
exc.get()->exception_record.exception_address = dumper_->crash_address();
exc.get()->thread_context = crashing_thread_context_;
return true;
}
bool WriteSystemInfoStream(MDRawDirectory* dirent) {
TypedMDRVA<MDRawSystemInfo> si(&minidump_writer_);
if (!si.Allocate())
return false;
my_memset(si.get(), 0, sizeof(MDRawSystemInfo));
dirent->stream_type = MD_SYSTEM_INFO_STREAM;
dirent->location = si.location();
WriteCPUInformation(si.get());
WriteOSInformation(si.get());
return true;
}
bool WriteDSODebugStream(MDRawDirectory* dirent) {
ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr) *>(dumper_->auxv()[AT_PHDR]);
char* base;
int phnum = dumper_->auxv()[AT_PHNUM];
if (!phnum || !phdr)
return false;
// Assume the program base is at the beginning of the same page as the PHDR
base = reinterpret_cast<char *>(reinterpret_cast<uintptr_t>(phdr) & ~0xfff);
// Search for the program PT_DYNAMIC segment
ElfW(Addr) dyn_addr = 0;
for (; phnum >= 0; phnum--, phdr++) {
ElfW(Phdr) ph;
if (!dumper_->CopyFromProcess(&ph, GetCrashThread(), phdr, sizeof(ph)))
return false;
// Adjust base address with the virtual address of the PT_LOAD segment
// corresponding to offset 0
if (ph.p_type == PT_LOAD && ph.p_offset == 0) {
base -= ph.p_vaddr;
}
if (ph.p_type == PT_DYNAMIC) {
dyn_addr = ph.p_vaddr;
}
}
if (!dyn_addr)
return false;
ElfW(Dyn) *dynamic = reinterpret_cast<ElfW(Dyn) *>(dyn_addr + base);
// The dynamic linker makes information available that helps gdb find all
// DSOs loaded into the program. If this information is indeed available,
// dump it to a MD_LINUX_DSO_DEBUG stream.
struct r_debug* r_debug = NULL;
uint32_t dynamic_length = 0;
for (int i = 0; ; ++i) {
ElfW(Dyn) dyn;
dynamic_length += sizeof(dyn);
if (!dumper_->CopyFromProcess(&dyn, GetCrashThread(), dynamic + i,
sizeof(dyn))) {
return false;
}
if (dyn.d_tag == DT_DEBUG) {
r_debug = reinterpret_cast<struct r_debug*>(dyn.d_un.d_ptr);
continue;
} else if (dyn.d_tag == DT_NULL) {
break;
}
}
// The "r_map" field of that r_debug struct contains a linked list of all
// loaded DSOs.
// Our list of DSOs potentially is different from the ones in the crashing
// process. So, we have to be careful to never dereference pointers
// directly. Instead, we use CopyFromProcess() everywhere.
// See <link.h> for a more detailed discussion of the how the dynamic
// loader communicates with debuggers.
// Count the number of loaded DSOs
int dso_count = 0;
struct r_debug debug_entry;
if (!dumper_->CopyFromProcess(&debug_entry, GetCrashThread(), r_debug,
sizeof(debug_entry))) {
return false;
}
for (struct link_map* ptr = debug_entry.r_map; ptr; ) {
struct link_map map;
if (!dumper_->CopyFromProcess(&map, GetCrashThread(), ptr, sizeof(map)))
return false;
ptr = map.l_next;
dso_count++;
}
MDRVA linkmap_rva = minidump_writer_.kInvalidMDRVA;
if (dso_count > 0) {
// If we have at least one DSO, create an array of MDRawLinkMap
// entries in the minidump file.
TypedMDRVA<MDRawLinkMap> linkmap(&minidump_writer_);
if (!linkmap.AllocateArray(dso_count))
return false;
linkmap_rva = linkmap.location().rva;
int idx = 0;
// Iterate over DSOs and write their information to mini dump
for (struct link_map* ptr = debug_entry.r_map; ptr; ) {
struct link_map map;
if (!dumper_->CopyFromProcess(&map, GetCrashThread(), ptr, sizeof(map)))
return false;
ptr = map.l_next;
char filename[257] = { 0 };
if (map.l_name) {
dumper_->CopyFromProcess(filename, GetCrashThread(), map.l_name,
sizeof(filename) - 1);
}
MDLocationDescriptor location;
if (!minidump_writer_.WriteString(filename, 0, &location))
return false;
MDRawLinkMap entry;
entry.name = location.rva;
entry.addr = map.l_addr;
entry.ld = reinterpret_cast<uintptr_t>(map.l_ld);
linkmap.CopyIndex(idx++, &entry);
}
}
// Write MD_LINUX_DSO_DEBUG record
TypedMDRVA<MDRawDebug> debug(&minidump_writer_);
if (!debug.AllocateObjectAndArray(1, dynamic_length))
return false;
my_memset(debug.get(), 0, sizeof(MDRawDebug));
dirent->stream_type = MD_LINUX_DSO_DEBUG;
dirent->location = debug.location();
debug.get()->version = debug_entry.r_version;
debug.get()->map = linkmap_rva;
debug.get()->dso_count = dso_count;
debug.get()->brk = debug_entry.r_brk;
debug.get()->ldbase = debug_entry.r_ldbase;
debug.get()->dynamic = reinterpret_cast<uintptr_t>(dynamic);
wasteful_vector<char> dso_debug_data(dumper_->allocator(), dynamic_length);
// The passed-in size to the constructor (above) is only a hint.
// Must call .resize() to do actual initialization of the elements.
dso_debug_data.resize(dynamic_length);
dumper_->CopyFromProcess(&dso_debug_data[0], GetCrashThread(), dynamic,
dynamic_length);
debug.CopyIndexAfterObject(0, &dso_debug_data[0], dynamic_length);
return true;
}
void set_minidump_size_limit(off_t limit) { minidump_size_limit_ = limit; }
private:
void* Alloc(unsigned bytes) {
return dumper_->allocator()->Alloc(bytes);
}
pid_t GetCrashThread() const {
return dumper_->crash_thread();
}
void NullifyDirectoryEntry(MDRawDirectory* dirent) {
dirent->stream_type = 0;
dirent->location.data_size = 0;
dirent->location.rva = 0;
}
#if defined(__i386__) || defined(__x86_64__) || defined(__mips__)
bool WriteCPUInformation(MDRawSystemInfo* sys_info) {
char vendor_id[sizeof(sys_info->cpu.x86_cpu_info.vendor_id) + 1] = {0};
static const char vendor_id_name[] = "vendor_id";
struct CpuInfoEntry {
const char* info_name;
int value;
bool found;
} cpu_info_table[] = {
{ "processor", -1, false },
#if defined(__i386__) || defined(__x86_64__)
{ "model", 0, false },
{ "stepping", 0, false },
{ "cpu family", 0, false },
#endif
};
// processor_architecture should always be set, do this first
sys_info->processor_architecture =
#if defined(__mips__)
MD_CPU_ARCHITECTURE_MIPS;
#elif defined(__i386__)
MD_CPU_ARCHITECTURE_X86;
#else
MD_CPU_ARCHITECTURE_AMD64;
#endif
const int fd = sys_open("/proc/cpuinfo", O_RDONLY, 0);
if (fd < 0)
return false;
{
PageAllocator allocator;
ProcCpuInfoReader* const reader = new(allocator) ProcCpuInfoReader(fd);
const char* field;
while (reader->GetNextField(&field)) {
for (size_t i = 0;
i < sizeof(cpu_info_table) / sizeof(cpu_info_table[0]);
i++) {
CpuInfoEntry* entry = &cpu_info_table[i];
if (i > 0 && entry->found) {
// except for the 'processor' field, ignore repeated values.
continue;
}
if (!my_strcmp(field, entry->info_name)) {
size_t value_len;
const char* value = reader->GetValueAndLen(&value_len);
if (value_len == 0)
continue;
uintptr_t val;
if (my_read_decimal_ptr(&val, value) == value)
continue;
entry->value = static_cast<int>(val);
entry->found = true;
}
}
// special case for vendor_id
if (!my_strcmp(field, vendor_id_name)) {
size_t value_len;
const char* value = reader->GetValueAndLen(&value_len);
if (value_len > 0)
my_strlcpy(vendor_id, value, sizeof(vendor_id));
}
}
sys_close(fd);
}
// make sure we got everything we wanted
for (size_t i = 0;
i < sizeof(cpu_info_table) / sizeof(cpu_info_table[0]);
i++) {
if (!cpu_info_table[i].found) {
return false;
}
}
// cpu_info_table[0] holds the last cpu id listed in /proc/cpuinfo,
// assuming this is the highest id, change it to the number of CPUs
// by adding one.
cpu_info_table[0].value++;
sys_info->number_of_processors = cpu_info_table[0].value;
#if defined(__i386__) || defined(__x86_64__)
sys_info->processor_level = cpu_info_table[3].value;
sys_info->processor_revision = cpu_info_table[1].value << 8 |
cpu_info_table[2].value;
#endif
if (vendor_id[0] != '\0') {
my_memcpy(sys_info->cpu.x86_cpu_info.vendor_id, vendor_id,
sizeof(sys_info->cpu.x86_cpu_info.vendor_id));
}
return true;
}
#elif defined(__arm__) || defined(__aarch64__)
bool WriteCPUInformation(MDRawSystemInfo* sys_info) {
// The CPUID value is broken up in several entries in /proc/cpuinfo.
// This table is used to rebuild it from the entries.
const struct CpuIdEntry {
const char* field;
char format;
char bit_lshift;
char bit_length;
} cpu_id_entries[] = {
{ "CPU implementer", 'x', 24, 8 },
{ "CPU variant", 'x', 20, 4 },
{ "CPU part", 'x', 4, 12 },
{ "CPU revision", 'd', 0, 4 },
};
// The ELF hwcaps are listed in the "Features" entry as textual tags.
// This table is used to rebuild them.
const struct CpuFeaturesEntry {
const char* tag;
uint32_t hwcaps;
} cpu_features_entries[] = {
#if defined(__arm__)
{ "swp", MD_CPU_ARM_ELF_HWCAP_SWP },
{ "half", MD_CPU_ARM_ELF_HWCAP_HALF },
{ "thumb", MD_CPU_ARM_ELF_HWCAP_THUMB },
{ "26bit", MD_CPU_ARM_ELF_HWCAP_26BIT },
{ "fastmult", MD_CPU_ARM_ELF_HWCAP_FAST_MULT },
{ "fpa", MD_CPU_ARM_ELF_HWCAP_FPA },
{ "vfp", MD_CPU_ARM_ELF_HWCAP_VFP },
{ "edsp", MD_CPU_ARM_ELF_HWCAP_EDSP },
{ "java", MD_CPU_ARM_ELF_HWCAP_JAVA },
{ "iwmmxt", MD_CPU_ARM_ELF_HWCAP_IWMMXT },
{ "crunch", MD_CPU_ARM_ELF_HWCAP_CRUNCH },
{ "thumbee", MD_CPU_ARM_ELF_HWCAP_THUMBEE },
{ "neon", MD_CPU_ARM_ELF_HWCAP_NEON },
{ "vfpv3", MD_CPU_ARM_ELF_HWCAP_VFPv3 },
{ "vfpv3d16", MD_CPU_ARM_ELF_HWCAP_VFPv3D16 },
{ "tls", MD_CPU_ARM_ELF_HWCAP_TLS },
{ "vfpv4", MD_CPU_ARM_ELF_HWCAP_VFPv4 },
{ "idiva", MD_CPU_ARM_ELF_HWCAP_IDIVA },
{ "idivt", MD_CPU_ARM_ELF_HWCAP_IDIVT },
{ "idiv", MD_CPU_ARM_ELF_HWCAP_IDIVA | MD_CPU_ARM_ELF_HWCAP_IDIVT },
#elif defined(__aarch64__)
// No hwcaps on aarch64.
#endif
};
// processor_architecture should always be set, do this first
sys_info->processor_architecture =
#if defined(__aarch64__)
MD_CPU_ARCHITECTURE_ARM64;
#else
MD_CPU_ARCHITECTURE_ARM;
#endif
// /proc/cpuinfo is not readable under various sandboxed environments
// (e.g. Android services with the android:isolatedProcess attribute)
// prepare for this by setting default values now, which will be
// returned when this happens.
//
// Note: Bogus values are used to distinguish between failures (to
// read /sys and /proc files) and really badly configured kernels.
sys_info->number_of_processors = 0;
sys_info->processor_level = 1U; // There is no ARMv1
sys_info->processor_revision = 42;
sys_info->cpu.arm_cpu_info.cpuid = 0;
sys_info->cpu.arm_cpu_info.elf_hwcaps = 0;
// Counting the number of CPUs involves parsing two sysfs files,
// because the content of /proc/cpuinfo will only mirror the number
// of 'online' cores, and thus will vary with time.
// See http://www.kernel.org/doc/Documentation/cputopology.txt
{
CpuSet cpus_present;
CpuSet cpus_possible;
int fd = sys_open("/sys/devices/system/cpu/present", O_RDONLY, 0);
if (fd >= 0) {
cpus_present.ParseSysFile(fd);
sys_close(fd);
fd = sys_open("/sys/devices/system/cpu/possible", O_RDONLY, 0);
if (fd >= 0) {
cpus_possible.ParseSysFile(fd);
sys_close(fd);
cpus_present.IntersectWith(cpus_possible);
int cpu_count = cpus_present.GetCount();
if (cpu_count > 255)
cpu_count = 255;
sys_info->number_of_processors = static_cast<uint8_t>(cpu_count);
}
}
}
// Parse /proc/cpuinfo to reconstruct the CPUID value, as well
// as the ELF hwcaps field. For the latter, it would be easier to
// read /proc/self/auxv but unfortunately, this file is not always
// readable from regular Android applications on later versions
// (>= 4.1) of the Android platform.
const int fd = sys_open("/proc/cpuinfo", O_RDONLY, 0);
if (fd < 0) {
// Do not return false here to allow the minidump generation
// to happen properly.
return true;
}
{
PageAllocator allocator;
ProcCpuInfoReader* const reader =
new(allocator) ProcCpuInfoReader(fd);
const char* field;
while (reader->GetNextField(&field)) {
for (size_t i = 0;
i < sizeof(cpu_id_entries)/sizeof(cpu_id_entries[0]);
++i) {
const CpuIdEntry* entry = &cpu_id_entries[i];
if (my_strcmp(entry->field, field) != 0)
continue;
uintptr_t result = 0;
const char* value = reader->GetValue();
const char* p = value;
if (value[0] == '0' && value[1] == 'x') {
p = my_read_hex_ptr(&result, value+2);
} else if (entry->format == 'x') {
p = my_read_hex_ptr(&result, value);
} else {
p = my_read_decimal_ptr(&result, value);
}
if (p == value)
continue;
result &= (1U << entry->bit_length)-1;
result <<= entry->bit_lshift;
sys_info->cpu.arm_cpu_info.cpuid |=
static_cast<uint32_t>(result);
}
#if defined(__arm__)
// Get the architecture version from the "Processor" field.
// Note that it is also available in the "CPU architecture" field,
// however, some existing kernels are misconfigured and will report
// invalid values here (e.g. 6, while the CPU is ARMv7-A based).
// The "Processor" field doesn't have this issue.
if (!my_strcmp(field, "Processor")) {
size_t value_len;
const char* value = reader->GetValueAndLen(&value_len);
// Expected format: <text> (v<level><endian>)
// Where <text> is some text like "ARMv7 Processor rev 2"
// and <level> is a decimal corresponding to the ARM
// architecture number. <endian> is either 'l' or 'b'
// and corresponds to the endianess, it is ignored here.
while (value_len > 0 && my_isspace(value[value_len-1]))
value_len--;
size_t nn = value_len;
while (nn > 0 && value[nn-1] != '(')
nn--;
if (nn > 0 && value[nn] == 'v') {
uintptr_t arch_level = 5;
my_read_decimal_ptr(&arch_level, value + nn + 1);
sys_info->processor_level = static_cast<uint16_t>(arch_level);
}
}
#elif defined(__aarch64__)
// The aarch64 architecture does not provide the architecture level
// in the Processor field, so we instead check the "CPU architecture"
// field.
if (!my_strcmp(field, "CPU architecture")) {
uintptr_t arch_level = 0;
const char* value = reader->GetValue();
const char* p = value;
p = my_read_decimal_ptr(&arch_level, value);
if (p == value)
continue;
sys_info->processor_level = static_cast<uint16_t>(arch_level);
}
#endif
// Rebuild the ELF hwcaps from the 'Features' field.
if (!my_strcmp(field, "Features")) {
size_t value_len;
const char* value = reader->GetValueAndLen(&value_len);
// Parse each space-separated tag.
while (value_len > 0) {
const char* tag = value;
size_t tag_len = value_len;
const char* p = my_strchr(tag, ' ');
if (p != NULL) {
tag_len = static_cast<size_t>(p - tag);
value += tag_len + 1;
value_len -= tag_len + 1;
} else {
tag_len = strlen(tag);
value_len = 0;
}
for (size_t i = 0;
i < sizeof(cpu_features_entries)/
sizeof(cpu_features_entries[0]);
++i) {
const CpuFeaturesEntry* entry = &cpu_features_entries[i];
if (tag_len == strlen(entry->tag) &&
!memcmp(tag, entry->tag, tag_len)) {
sys_info->cpu.arm_cpu_info.elf_hwcaps |= entry->hwcaps;
break;
}
}
}
}
}
sys_close(fd);
}
return true;
}
#else
# error "Unsupported CPU"
#endif
bool WriteFile(MDLocationDescriptor* result, const char* filename) {
const int fd = sys_open(filename, O_RDONLY, 0);
if (fd < 0)
return false;
// We can't stat the files because several of the files that we want to
// read are kernel seqfiles, which always have a length of zero. So we have
// to read as much as we can into a buffer.
static const unsigned kBufSize = 1024 - 2*sizeof(void*);
struct Buffers {
Buffers* next;
size_t len;
uint8_t data[kBufSize];
} *buffers = reinterpret_cast<Buffers*>(Alloc(sizeof(Buffers)));
buffers->next = NULL;
buffers->len = 0;
size_t total = 0;
for (Buffers* bufptr = buffers;;) {
ssize_t r;
do {
r = sys_read(fd, &bufptr->data[bufptr->len], kBufSize - bufptr->len);
} while (r == -1 && errno == EINTR);
if (r < 1)
break;
total += r;
bufptr->len += r;
if (bufptr->len == kBufSize) {
bufptr->next = reinterpret_cast<Buffers*>(Alloc(sizeof(Buffers)));
bufptr = bufptr->next;
bufptr->next = NULL;
bufptr->len = 0;
}
}
sys_close(fd);
if (!total)
return false;
UntypedMDRVA memory(&minidump_writer_);
if (!memory.Allocate(total))
return false;
for (MDRVA pos = memory.position(); buffers; buffers = buffers->next) {
// Check for special case of a zero-length buffer. This should only
// occur if a file's size happens to be a multiple of the buffer's
// size, in which case the final sys_read() will have resulted in
// zero bytes being read after the final buffer was just allocated.
if (buffers->len == 0) {
// This can only occur with final buffer.
assert(buffers->next == NULL);
continue;
}
memory.Copy(pos, &buffers->data, buffers->len);
pos += buffers->len;
}
*result = memory.location();
return true;
}
bool WriteOSInformation(MDRawSystemInfo* sys_info) {
#if defined(__ANDROID__)
sys_info->platform_id = MD_OS_ANDROID;
#else
sys_info->platform_id = MD_OS_LINUX;
#endif
struct utsname uts;
if (uname(&uts))
return false;
static const size_t buf_len = 512;
char buf[buf_len] = {0};
size_t space_left = buf_len - 1;
const char* info_table[] = {
uts.sysname,
uts.release,
uts.version,
uts.machine,
NULL
};
bool first_item = true;
for (const char** cur_info = info_table; *cur_info; cur_info++) {
static const char separator[] = " ";
size_t separator_len = sizeof(separator) - 1;
size_t info_len = my_strlen(*cur_info);
if (info_len == 0)
continue;
if (space_left < info_len + (first_item ? 0 : separator_len))
break;
if (!first_item) {
my_strlcat(buf, separator, sizeof(buf));
space_left -= separator_len;
}
first_item = false;
my_strlcat(buf, *cur_info, sizeof(buf));
space_left -= info_len;
}
MDLocationDescriptor location;
if (!minidump_writer_.WriteString(buf, 0, &location))
return false;
sys_info->csd_version_rva = location.rva;
return true;
}
bool WriteProcFile(MDLocationDescriptor* result, pid_t pid,
const char* filename) {
char buf[NAME_MAX];
if (!dumper_->BuildProcPath(buf, pid, filename))
return false;
return WriteFile(result, buf);
}
// Only one of the 2 member variables below should be set to a valid value.
const int fd_; // File descriptor where the minidum should be written.
const char* path_; // Path to the file where the minidum should be written.
const struct ucontext* const ucontext_; // also from the signal handler
#if !defined(__ARM_EABI__) && !defined(__mips__)
const google_breakpad::fpstate_t* const float_state_; // ditto
#endif
LinuxDumper* dumper_;
MinidumpFileWriter minidump_writer_;
off_t minidump_size_limit_;
MDLocationDescriptor crashing_thread_context_;
// Blocks of memory written to the dump. These are all currently
// written while writing the thread list stream, but saved here
// so a memory list stream can be written afterwards.
wasteful_vector<MDMemoryDescriptor> memory_blocks_;
// Additional information about some mappings provided by the caller.
const MappingList& mapping_list_;
// Additional memory regions to be included in the dump,
// provided by the caller.
const AppMemoryList& app_memory_list_;
};
bool WriteMinidumpImpl(const char* minidump_path,
int minidump_fd,
off_t minidump_size_limit,
pid_t crashing_process,
const void* blob, size_t blob_size,
const MappingList& mappings,
const AppMemoryList& appmem) {
LinuxPtraceDumper dumper(crashing_process);
const ExceptionHandler::CrashContext* context = NULL;
if (blob) {
if (blob_size != sizeof(ExceptionHandler::CrashContext))
return false;
context = reinterpret_cast<const ExceptionHandler::CrashContext*>(blob);
dumper.set_crash_address(
reinterpret_cast<uintptr_t>(context->siginfo.si_addr));
dumper.set_crash_signal(context->siginfo.si_signo);
dumper.set_crash_thread(context->tid);
}
MinidumpWriter writer(minidump_path, minidump_fd, context, mappings,
appmem, &dumper);
// Set desired limit for file size of minidump (-1 means no limit).
writer.set_minidump_size_limit(minidump_size_limit);
if (!writer.Init())
return false;
return writer.Dump();
}
} // namespace
namespace google_breakpad {
bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
const void* blob, size_t blob_size) {
return WriteMinidumpImpl(minidump_path, -1, -1,
crashing_process, blob, blob_size,
MappingList(), AppMemoryList());
}
bool WriteMinidump(int minidump_fd, pid_t crashing_process,
const void* blob, size_t blob_size) {
return WriteMinidumpImpl(NULL, minidump_fd, -1,
crashing_process, blob, blob_size,
MappingList(), AppMemoryList());
}
bool WriteMinidump(const char* minidump_path, pid_t process,
pid_t process_blamed_thread) {
LinuxPtraceDumper dumper(process);
// MinidumpWriter will set crash address
dumper.set_crash_signal(MD_EXCEPTION_CODE_LIN_DUMP_REQUESTED);
dumper.set_crash_thread(process_blamed_thread);
MinidumpWriter writer(minidump_path, -1, NULL, MappingList(),
AppMemoryList(), &dumper);
if (!writer.Init())
return false;
return writer.Dump();
}
bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
const void* blob, size_t blob_size,
const MappingList& mappings,
const AppMemoryList& appmem) {
return WriteMinidumpImpl(minidump_path, -1, -1, crashing_process,
blob, blob_size,
mappings, appmem);
}
bool WriteMinidump(int minidump_fd, pid_t crashing_process,
const void* blob, size_t blob_size,
const MappingList& mappings,
const AppMemoryList& appmem) {
return WriteMinidumpImpl(NULL, minidump_fd, -1, crashing_process,
blob, blob_size,
mappings, appmem);
}
bool WriteMinidump(const char* minidump_path, off_t minidump_size_limit,
pid_t crashing_process,
const void* blob, size_t blob_size,
const MappingList& mappings,
const AppMemoryList& appmem) {
return WriteMinidumpImpl(minidump_path, -1, minidump_size_limit,
crashing_process, blob, blob_size,
mappings, appmem);
}
bool WriteMinidump(int minidump_fd, off_t minidump_size_limit,
pid_t crashing_process,
const void* blob, size_t blob_size,
const MappingList& mappings,
const AppMemoryList& appmem) {
return WriteMinidumpImpl(NULL, minidump_fd, minidump_size_limit,
crashing_process, blob, blob_size,
mappings, appmem);
}
bool WriteMinidump(const char* filename,
const MappingList& mappings,
const AppMemoryList& appmem,
LinuxDumper* dumper) {
MinidumpWriter writer(filename, -1, NULL, mappings, appmem, dumper);
if (!writer.Init())
return false;
return writer.Dump();
}
} // namespace google_breakpad