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Diffstat (limited to '')
| -rw-r--r-- | tools/profiler/lul/LulElf.cpp | 887 |
1 files changed, 887 insertions, 0 deletions
diff --git a/tools/profiler/lul/LulElf.cpp b/tools/profiler/lul/LulElf.cpp new file mode 100644 index 0000000000..28980a1349 --- /dev/null +++ b/tools/profiler/lul/LulElf.cpp @@ -0,0 +1,887 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ + +// Copyright (c) 2006, 2011, 2012 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. + +// Restructured in 2009 by: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com> + +// (derived from) +// dump_symbols.cc: implement google_breakpad::WriteSymbolFile: +// Find all the debugging info in a file and dump it as a Breakpad symbol file. +// +// dump_symbols.h: Read debugging information from an ELF file, and write +// it out as a Breakpad symbol file. + +// This file is derived from the following files in +// toolkit/crashreporter/google-breakpad: +// src/common/linux/dump_symbols.cc +// src/common/linux/elfutils.cc +// src/common/linux/file_id.cc + +#include <errno.h> +#include <fcntl.h> +#include <libgen.h> +#include <stdio.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <unistd.h> +#include <arpa/inet.h> + +#include <set> +#include <string> +#include <vector> + +#include "mozilla/Assertions.h" +#include "mozilla/Sprintf.h" + +#include "PlatformMacros.h" +#include "LulCommonExt.h" +#include "LulDwarfExt.h" +#include "LulElfInt.h" +#include "LulMainInt.h" + +#if defined(GP_PLAT_arm_android) && !defined(SHT_ARM_EXIDX) +// bionic and older glibsc don't define it +# define SHT_ARM_EXIDX (SHT_LOPROC + 1) +#endif + +#if (defined(GP_PLAT_amd64_linux) || defined(GP_PLAT_amd64_android)) && \ + !defined(SHT_X86_64_UNWIND) +// This is sometimes necessary on x86_64-android and x86_64-linux. +# define SHT_X86_64_UNWIND 0x70000001 +#endif + +// Old Linux header doesn't define EM_AARCH64 +#ifndef EM_AARCH64 +# define EM_AARCH64 183 +#endif + +// This namespace contains helper functions. +namespace { + +using lul::DwarfCFIToModule; +using lul::FindElfSectionByName; +using lul::GetOffset; +using lul::IsValidElf; +using lul::Module; +using lul::scoped_ptr; +using lul::Summariser; +using lul::UniqueStringUniverse; +using std::set; +using std::string; +using std::vector; + +// +// FDWrapper +// +// Wrapper class to make sure opened file is closed. +// +class FDWrapper { + public: + explicit FDWrapper(int fd) : fd_(fd) {} + ~FDWrapper() { + if (fd_ != -1) close(fd_); + } + int get() { return fd_; } + int release() { + int fd = fd_; + fd_ = -1; + return fd; + } + + private: + int fd_; +}; + +// +// MmapWrapper +// +// Wrapper class to make sure mapped regions are unmapped. +// +class MmapWrapper { + public: + MmapWrapper() : is_set_(false), base_(NULL), size_(0) {} + ~MmapWrapper() { + if (is_set_ && base_ != NULL) { + MOZ_ASSERT(size_ > 0); + munmap(base_, size_); + } + } + void set(void* mapped_address, size_t mapped_size) { + is_set_ = true; + base_ = mapped_address; + size_ = mapped_size; + } + void release() { + MOZ_ASSERT(is_set_); + is_set_ = false; + base_ = NULL; + size_ = 0; + } + + private: + bool is_set_; + void* base_; + size_t size_; +}; + +// Set NUM_DW_REGNAMES to be the number of Dwarf register names +// appropriate to the machine architecture given in HEADER. Return +// true on success, or false if HEADER's machine architecture is not +// supported. +template <typename ElfClass> +bool DwarfCFIRegisterNames(const typename ElfClass::Ehdr* elf_header, + unsigned int* num_dw_regnames) { + switch (elf_header->e_machine) { + case EM_386: + *num_dw_regnames = DwarfCFIToModule::RegisterNames::I386(); + return true; + case EM_ARM: + *num_dw_regnames = DwarfCFIToModule::RegisterNames::ARM(); + return true; + case EM_X86_64: + *num_dw_regnames = DwarfCFIToModule::RegisterNames::X86_64(); + return true; + case EM_MIPS: + *num_dw_regnames = DwarfCFIToModule::RegisterNames::MIPS(); + return true; + case EM_AARCH64: + *num_dw_regnames = DwarfCFIToModule::RegisterNames::ARM64(); + return true; + default: + MOZ_ASSERT(0); + return false; + } +} + +template <typename ElfClass> +bool LoadDwarfCFI(const string& dwarf_filename, + const typename ElfClass::Ehdr* elf_header, + const char* section_name, + const typename ElfClass::Shdr* section, const bool eh_frame, + const typename ElfClass::Shdr* got_section, + const typename ElfClass::Shdr* text_section, + const bool big_endian, SecMap* smap, uintptr_t text_bias, + UniqueStringUniverse* usu, void (*log)(const char*)) { + // Find the appropriate set of register names for this file's + // architecture. + unsigned int num_dw_regs = 0; + if (!DwarfCFIRegisterNames<ElfClass>(elf_header, &num_dw_regs)) { + fprintf(stderr, + "%s: unrecognized ELF machine architecture '%d';" + " cannot convert DWARF call frame information\n", + dwarf_filename.c_str(), elf_header->e_machine); + return false; + } + + const lul::Endianness endianness = + big_endian ? lul::ENDIANNESS_BIG : lul::ENDIANNESS_LITTLE; + + // Find the call frame information and its size. + const char* cfi = GetOffset<ElfClass, char>(elf_header, section->sh_offset); + size_t cfi_size = section->sh_size; + + // Plug together the parser, handler, and their entourages. + + // Here's a summariser, which will receive the output of the + // parser, create summaries, and add them to |smap|. + Summariser summ(smap, text_bias, log); + + lul::ByteReader reader(endianness); + reader.SetAddressSize(ElfClass::kAddrSize); + + DwarfCFIToModule::Reporter module_reporter(log, dwarf_filename, section_name); + DwarfCFIToModule handler(num_dw_regs, &module_reporter, &reader, usu, &summ); + + // Provide the base addresses for .eh_frame encoded pointers, if + // possible. + reader.SetCFIDataBase(section->sh_addr, cfi); + if (got_section) reader.SetDataBase(got_section->sh_addr); + if (text_section) reader.SetTextBase(text_section->sh_addr); + + lul::CallFrameInfo::Reporter dwarf_reporter(log, dwarf_filename, + section_name); + lul::CallFrameInfo parser(cfi, cfi_size, &reader, &handler, &dwarf_reporter, + eh_frame); + parser.Start(); + + return true; +} + +bool LoadELF(const string& obj_file, MmapWrapper* map_wrapper, + void** elf_header) { + int obj_fd = open(obj_file.c_str(), O_RDONLY); + if (obj_fd < 0) { + fprintf(stderr, "Failed to open ELF file '%s': %s\n", obj_file.c_str(), + strerror(errno)); + return false; + } + FDWrapper obj_fd_wrapper(obj_fd); + struct stat st; + if (fstat(obj_fd, &st) != 0 && st.st_size <= 0) { + fprintf(stderr, "Unable to fstat ELF file '%s': %s\n", obj_file.c_str(), + strerror(errno)); + return false; + } + // Mapping it read-only is good enough. In any case, mapping it + // read-write confuses Valgrind's debuginfo acquire/discard + // heuristics, making it hard to profile the profiler. + void* obj_base = mmap(nullptr, st.st_size, PROT_READ, MAP_PRIVATE, obj_fd, 0); + if (obj_base == MAP_FAILED) { + fprintf(stderr, "Failed to mmap ELF file '%s': %s\n", obj_file.c_str(), + strerror(errno)); + return false; + } + map_wrapper->set(obj_base, st.st_size); + *elf_header = obj_base; + if (!IsValidElf(*elf_header)) { + fprintf(stderr, "Not a valid ELF file: %s\n", obj_file.c_str()); + return false; + } + return true; +} + +// Get the endianness of ELF_HEADER. If it's invalid, return false. +template <typename ElfClass> +bool ElfEndianness(const typename ElfClass::Ehdr* elf_header, + bool* big_endian) { + if (elf_header->e_ident[EI_DATA] == ELFDATA2LSB) { + *big_endian = false; + return true; + } + if (elf_header->e_ident[EI_DATA] == ELFDATA2MSB) { + *big_endian = true; + return true; + } + + fprintf(stderr, "bad data encoding in ELF header: %d\n", + elf_header->e_ident[EI_DATA]); + return false; +} + +// +// LoadSymbolsInfo +// +// Holds the state between the two calls to LoadSymbols() in case it's necessary +// to follow the .gnu_debuglink section and load debug information from a +// different file. +// +template <typename ElfClass> +class LoadSymbolsInfo { + public: + typedef typename ElfClass::Addr Addr; + + explicit LoadSymbolsInfo(const vector<string>& dbg_dirs) + : debug_dirs_(dbg_dirs), has_loading_addr_(false) {} + + // Keeps track of which sections have been loaded so sections don't + // accidentally get loaded twice from two different files. + void LoadedSection(const string& section) { + if (loaded_sections_.count(section) == 0) { + loaded_sections_.insert(section); + } else { + fprintf(stderr, "Section %s has already been loaded.\n", section.c_str()); + } + } + + string debuglink_file() const { return debuglink_file_; } + + private: + const vector<string>& debug_dirs_; // Directories in which to + // search for the debug ELF file. + + string debuglink_file_; // Full path to the debug ELF file. + + bool has_loading_addr_; // Indicate if LOADING_ADDR_ is valid. + + set<string> loaded_sections_; // Tracks the Loaded ELF sections + // between calls to LoadSymbols(). +}; + +// Find the preferred loading address of the binary. +template <typename ElfClass> +typename ElfClass::Addr GetLoadingAddress( + const typename ElfClass::Phdr* program_headers, int nheader) { + typedef typename ElfClass::Phdr Phdr; + + // For non-PIC executables (e_type == ET_EXEC), the load address is + // the start address of the first PT_LOAD segment. (ELF requires + // the segments to be sorted by load address.) For PIC executables + // and dynamic libraries (e_type == ET_DYN), this address will + // normally be zero. + for (int i = 0; i < nheader; ++i) { + const Phdr& header = program_headers[i]; + if (header.p_type == PT_LOAD) return header.p_vaddr; + } + return 0; +} + +template <typename ElfClass> +bool LoadSymbols(const string& obj_file, const bool big_endian, + const typename ElfClass::Ehdr* elf_header, + const bool read_gnu_debug_link, + LoadSymbolsInfo<ElfClass>* info, SecMap* smap, void* rx_avma, + size_t rx_size, UniqueStringUniverse* usu, + void (*log)(const char*)) { + typedef typename ElfClass::Phdr Phdr; + typedef typename ElfClass::Shdr Shdr; + + char buf[500]; + SprintfLiteral(buf, "LoadSymbols: BEGIN %s\n", obj_file.c_str()); + buf[sizeof(buf) - 1] = 0; + log(buf); + + // This is how the text bias is calculated. + // BEGIN CALCULATE BIAS + uintptr_t loading_addr = GetLoadingAddress<ElfClass>( + GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff), + elf_header->e_phnum); + uintptr_t text_bias = ((uintptr_t)rx_avma) - loading_addr; + SprintfLiteral(buf, "LoadSymbols: rx_avma=%llx, text_bias=%llx", + (unsigned long long int)(uintptr_t)rx_avma, + (unsigned long long int)text_bias); + buf[sizeof(buf) - 1] = 0; + log(buf); + // END CALCULATE BIAS + + const Shdr* sections = + GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff); + const Shdr* section_names = sections + elf_header->e_shstrndx; + const char* names = + GetOffset<ElfClass, char>(elf_header, section_names->sh_offset); + const char* names_end = names + section_names->sh_size; + bool found_usable_info = false; + + // Dwarf Call Frame Information (CFI) is actually independent from + // the other DWARF debugging information, and can be used alone. + const Shdr* dwarf_cfi_section = + FindElfSectionByName<ElfClass>(".debug_frame", SHT_PROGBITS, sections, + names, names_end, elf_header->e_shnum); + if (dwarf_cfi_section) { + // Ignore the return value of this function; even without call frame + // information, the other debugging information could be perfectly + // useful. + info->LoadedSection(".debug_frame"); + bool result = LoadDwarfCFI<ElfClass>(obj_file, elf_header, ".debug_frame", + dwarf_cfi_section, false, 0, 0, + big_endian, smap, text_bias, usu, log); + found_usable_info = found_usable_info || result; + if (result) log("LoadSymbols: read CFI from .debug_frame"); + } + + // Linux C++ exception handling information can also provide + // unwinding data. + const Shdr* eh_frame_section = + FindElfSectionByName<ElfClass>(".eh_frame", SHT_PROGBITS, sections, names, + names_end, elf_header->e_shnum); +#if defined(GP_PLAT_amd64_linux) || defined(GP_PLAT_amd64_android) + if (!eh_frame_section) { + // Possibly depending on which linker created libxul.so, on x86_64-linux + // and -android, .eh_frame may instead have the SHT_X86_64_UNWIND type. + eh_frame_section = + FindElfSectionByName<ElfClass>(".eh_frame", SHT_X86_64_UNWIND, sections, + names, names_end, elf_header->e_shnum); + } +#endif + if (eh_frame_section) { + // Pointers in .eh_frame data may be relative to the base addresses of + // certain sections. Provide those sections if present. + const Shdr* got_section = FindElfSectionByName<ElfClass>( + ".got", SHT_PROGBITS, sections, names, names_end, elf_header->e_shnum); + const Shdr* text_section = FindElfSectionByName<ElfClass>( + ".text", SHT_PROGBITS, sections, names, names_end, elf_header->e_shnum); + info->LoadedSection(".eh_frame"); + // As above, ignore the return value of this function. + bool result = LoadDwarfCFI<ElfClass>( + obj_file, elf_header, ".eh_frame", eh_frame_section, true, got_section, + text_section, big_endian, smap, text_bias, usu, log); + found_usable_info = found_usable_info || result; + if (result) log("LoadSymbols: read CFI from .eh_frame"); + } + + SprintfLiteral(buf, "LoadSymbols: END %s\n", obj_file.c_str()); + buf[sizeof(buf) - 1] = 0; + log(buf); + + return found_usable_info; +} + +// Return the breakpad symbol file identifier for the architecture of +// ELF_HEADER. +template <typename ElfClass> +const char* ElfArchitecture(const typename ElfClass::Ehdr* elf_header) { + typedef typename ElfClass::Half Half; + Half arch = elf_header->e_machine; + switch (arch) { + case EM_386: + return "x86"; + case EM_ARM: + return "arm"; + case EM_AARCH64: + return "arm64"; + case EM_MIPS: + return "mips"; + case EM_PPC64: + return "ppc64"; + case EM_PPC: + return "ppc"; + case EM_S390: + return "s390"; + case EM_SPARC: + return "sparc"; + case EM_SPARCV9: + return "sparcv9"; + case EM_X86_64: + return "x86_64"; + default: + return NULL; + } +} + +// Format the Elf file identifier in IDENTIFIER as a UUID with the +// dashes removed. +string FormatIdentifier(unsigned char identifier[16]) { + char identifier_str[40]; + lul::FileID::ConvertIdentifierToString(identifier, identifier_str, + sizeof(identifier_str)); + string id_no_dash; + for (int i = 0; identifier_str[i] != '\0'; ++i) + if (identifier_str[i] != '-') id_no_dash += identifier_str[i]; + // Add an extra "0" by the end. PDB files on Windows have an 'age' + // number appended to the end of the file identifier; this isn't + // really used or necessary on other platforms, but be consistent. + id_no_dash += '0'; + return id_no_dash; +} + +// Return the non-directory portion of FILENAME: the portion after the +// last slash, or the whole filename if there are no slashes. +string BaseFileName(const string& filename) { + // Lots of copies! basename's behavior is less than ideal. + char* c_filename = strdup(filename.c_str()); + string base = basename(c_filename); + free(c_filename); + return base; +} + +template <typename ElfClass> +bool ReadSymbolDataElfClass(const typename ElfClass::Ehdr* elf_header, + const string& obj_filename, + const vector<string>& debug_dirs, SecMap* smap, + void* rx_avma, size_t rx_size, + UniqueStringUniverse* usu, + void (*log)(const char*)) { + typedef typename ElfClass::Ehdr Ehdr; + + unsigned char identifier[16]; + if (!lul ::FileID::ElfFileIdentifierFromMappedFile(elf_header, identifier)) { + fprintf(stderr, "%s: unable to generate file identifier\n", + obj_filename.c_str()); + return false; + } + + const char* architecture = ElfArchitecture<ElfClass>(elf_header); + if (!architecture) { + fprintf(stderr, "%s: unrecognized ELF machine architecture: %d\n", + obj_filename.c_str(), elf_header->e_machine); + return false; + } + + // Figure out what endianness this file is. + bool big_endian; + if (!ElfEndianness<ElfClass>(elf_header, &big_endian)) return false; + + string name = BaseFileName(obj_filename); + string os = "Linux"; + string id = FormatIdentifier(identifier); + + LoadSymbolsInfo<ElfClass> info(debug_dirs); + if (!LoadSymbols<ElfClass>(obj_filename, big_endian, elf_header, + !debug_dirs.empty(), &info, smap, rx_avma, rx_size, + usu, log)) { + const string debuglink_file = info.debuglink_file(); + if (debuglink_file.empty()) return false; + + // Load debuglink ELF file. + fprintf(stderr, "Found debugging info in %s\n", debuglink_file.c_str()); + MmapWrapper debug_map_wrapper; + Ehdr* debug_elf_header = NULL; + if (!LoadELF(debuglink_file, &debug_map_wrapper, + reinterpret_cast<void**>(&debug_elf_header))) + return false; + // Sanity checks to make sure everything matches up. + const char* debug_architecture = + ElfArchitecture<ElfClass>(debug_elf_header); + if (!debug_architecture) { + fprintf(stderr, "%s: unrecognized ELF machine architecture: %d\n", + debuglink_file.c_str(), debug_elf_header->e_machine); + return false; + } + if (strcmp(architecture, debug_architecture)) { + fprintf(stderr, + "%s with ELF machine architecture %s does not match " + "%s with ELF architecture %s\n", + debuglink_file.c_str(), debug_architecture, obj_filename.c_str(), + architecture); + return false; + } + + bool debug_big_endian; + if (!ElfEndianness<ElfClass>(debug_elf_header, &debug_big_endian)) + return false; + if (debug_big_endian != big_endian) { + fprintf(stderr, "%s and %s does not match in endianness\n", + obj_filename.c_str(), debuglink_file.c_str()); + return false; + } + + if (!LoadSymbols<ElfClass>(debuglink_file, debug_big_endian, + debug_elf_header, false, &info, smap, rx_avma, + rx_size, usu, log)) { + return false; + } + } + + return true; +} + +} // namespace + +namespace lul { + +bool ReadSymbolDataInternal(const uint8_t* obj_file, const string& obj_filename, + const vector<string>& debug_dirs, SecMap* smap, + void* rx_avma, size_t rx_size, + UniqueStringUniverse* usu, + void (*log)(const char*)) { + if (!IsValidElf(obj_file)) { + fprintf(stderr, "Not a valid ELF file: %s\n", obj_filename.c_str()); + return false; + } + + int elfclass = ElfClass(obj_file); + if (elfclass == ELFCLASS32) { + return ReadSymbolDataElfClass<ElfClass32>( + reinterpret_cast<const Elf32_Ehdr*>(obj_file), obj_filename, debug_dirs, + smap, rx_avma, rx_size, usu, log); + } + if (elfclass == ELFCLASS64) { + return ReadSymbolDataElfClass<ElfClass64>( + reinterpret_cast<const Elf64_Ehdr*>(obj_file), obj_filename, debug_dirs, + smap, rx_avma, rx_size, usu, log); + } + + return false; +} + +bool ReadSymbolData(const string& obj_file, const vector<string>& debug_dirs, + SecMap* smap, void* rx_avma, size_t rx_size, + UniqueStringUniverse* usu, void (*log)(const char*)) { + MmapWrapper map_wrapper; + void* elf_header = NULL; + if (!LoadELF(obj_file, &map_wrapper, &elf_header)) return false; + + return ReadSymbolDataInternal(reinterpret_cast<uint8_t*>(elf_header), + obj_file, debug_dirs, smap, rx_avma, rx_size, + usu, log); +} + +namespace { + +template <typename ElfClass> +void FindElfClassSection(const char* elf_base, const char* section_name, + typename ElfClass::Word section_type, + const void** section_start, int* section_size) { + typedef typename ElfClass::Ehdr Ehdr; + typedef typename ElfClass::Shdr Shdr; + + MOZ_ASSERT(elf_base); + MOZ_ASSERT(section_start); + MOZ_ASSERT(section_size); + + MOZ_ASSERT(strncmp(elf_base, ELFMAG, SELFMAG) == 0); + + const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base); + MOZ_ASSERT(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); + + const Shdr* sections = + GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff); + const Shdr* section_names = sections + elf_header->e_shstrndx; + const char* names = + GetOffset<ElfClass, char>(elf_header, section_names->sh_offset); + const char* names_end = names + section_names->sh_size; + + const Shdr* section = + FindElfSectionByName<ElfClass>(section_name, section_type, sections, + names, names_end, elf_header->e_shnum); + + if (section != NULL && section->sh_size > 0) { + *section_start = elf_base + section->sh_offset; + *section_size = section->sh_size; + } +} + +template <typename ElfClass> +void FindElfClassSegment(const char* elf_base, + typename ElfClass::Word segment_type, + const void** segment_start, int* segment_size) { + typedef typename ElfClass::Ehdr Ehdr; + typedef typename ElfClass::Phdr Phdr; + + MOZ_ASSERT(elf_base); + MOZ_ASSERT(segment_start); + MOZ_ASSERT(segment_size); + + MOZ_ASSERT(strncmp(elf_base, ELFMAG, SELFMAG) == 0); + + const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base); + MOZ_ASSERT(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); + + const Phdr* phdrs = + GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff); + + for (int i = 0; i < elf_header->e_phnum; ++i) { + if (phdrs[i].p_type == segment_type) { + *segment_start = elf_base + phdrs[i].p_offset; + *segment_size = phdrs[i].p_filesz; + return; + } + } +} + +} // namespace + +bool IsValidElf(const void* elf_base) { + return strncmp(reinterpret_cast<const char*>(elf_base), ELFMAG, SELFMAG) == 0; +} + +int ElfClass(const void* elf_base) { + const ElfW(Ehdr)* elf_header = reinterpret_cast<const ElfW(Ehdr)*>(elf_base); + + return elf_header->e_ident[EI_CLASS]; +} + +bool FindElfSection(const void* elf_mapped_base, const char* section_name, + uint32_t section_type, const void** section_start, + int* section_size, int* elfclass) { + MOZ_ASSERT(elf_mapped_base); + MOZ_ASSERT(section_start); + MOZ_ASSERT(section_size); + + *section_start = NULL; + *section_size = 0; + + if (!IsValidElf(elf_mapped_base)) return false; + + int cls = ElfClass(elf_mapped_base); + if (elfclass) { + *elfclass = cls; + } + + const char* elf_base = static_cast<const char*>(elf_mapped_base); + + if (cls == ELFCLASS32) { + FindElfClassSection<ElfClass32>(elf_base, section_name, section_type, + section_start, section_size); + return *section_start != NULL; + } else if (cls == ELFCLASS64) { + FindElfClassSection<ElfClass64>(elf_base, section_name, section_type, + section_start, section_size); + return *section_start != NULL; + } + + return false; +} + +bool FindElfSegment(const void* elf_mapped_base, uint32_t segment_type, + const void** segment_start, int* segment_size, + int* elfclass) { + MOZ_ASSERT(elf_mapped_base); + MOZ_ASSERT(segment_start); + MOZ_ASSERT(segment_size); + + *segment_start = NULL; + *segment_size = 0; + + if (!IsValidElf(elf_mapped_base)) return false; + + int cls = ElfClass(elf_mapped_base); + if (elfclass) { + *elfclass = cls; + } + + const char* elf_base = static_cast<const char*>(elf_mapped_base); + + if (cls == ELFCLASS32) { + FindElfClassSegment<ElfClass32>(elf_base, segment_type, segment_start, + segment_size); + return *segment_start != NULL; + } else if (cls == ELFCLASS64) { + FindElfClassSegment<ElfClass64>(elf_base, segment_type, segment_start, + segment_size); + return *segment_start != NULL; + } + + return false; +} + +// (derived from) +// file_id.cc: Return a unique identifier for a file +// +// See file_id.h for documentation +// + +// ELF note name and desc are 32-bits word padded. +#define NOTE_PADDING(a) ((a + 3) & ~3) + +// These functions are also used inside the crashed process, so be safe +// and use the syscall/libc wrappers instead of direct syscalls or libc. + +template <typename ElfClass> +static bool ElfClassBuildIDNoteIdentifier(const void* section, int length, + uint8_t identifier[kMDGUIDSize]) { + typedef typename ElfClass::Nhdr Nhdr; + + const void* section_end = reinterpret_cast<const char*>(section) + length; + const Nhdr* note_header = reinterpret_cast<const Nhdr*>(section); + while (reinterpret_cast<const void*>(note_header) < section_end) { + if (note_header->n_type == NT_GNU_BUILD_ID) break; + note_header = reinterpret_cast<const Nhdr*>( + reinterpret_cast<const char*>(note_header) + sizeof(Nhdr) + + NOTE_PADDING(note_header->n_namesz) + + NOTE_PADDING(note_header->n_descsz)); + } + if (reinterpret_cast<const void*>(note_header) >= section_end || + note_header->n_descsz == 0) { + return false; + } + + const char* build_id = reinterpret_cast<const char*>(note_header) + + sizeof(Nhdr) + NOTE_PADDING(note_header->n_namesz); + // Copy as many bits of the build ID as will fit + // into the GUID space. + memset(identifier, 0, kMDGUIDSize); + memcpy(identifier, build_id, + std::min(kMDGUIDSize, (size_t)note_header->n_descsz)); + + return true; +} + +// Attempt to locate a .note.gnu.build-id section in an ELF binary +// and copy as many bytes of it as will fit into |identifier|. +static bool FindElfBuildIDNote(const void* elf_mapped_base, + uint8_t identifier[kMDGUIDSize]) { + void* note_section; + int note_size, elfclass; + if ((!FindElfSegment(elf_mapped_base, PT_NOTE, (const void**)¬e_section, + ¬e_size, &elfclass) || + note_size == 0) && + (!FindElfSection(elf_mapped_base, ".note.gnu.build-id", SHT_NOTE, + (const void**)¬e_section, ¬e_size, &elfclass) || + note_size == 0)) { + return false; + } + + if (elfclass == ELFCLASS32) { + return ElfClassBuildIDNoteIdentifier<ElfClass32>(note_section, note_size, + identifier); + } else if (elfclass == ELFCLASS64) { + return ElfClassBuildIDNoteIdentifier<ElfClass64>(note_section, note_size, + identifier); + } + + return false; +} + +// Attempt to locate the .text section of an ELF binary and generate +// a simple hash by XORing the first page worth of bytes into |identifier|. +static bool HashElfTextSection(const void* elf_mapped_base, + uint8_t identifier[kMDGUIDSize]) { + void* text_section; + int text_size; + if (!FindElfSection(elf_mapped_base, ".text", SHT_PROGBITS, + (const void**)&text_section, &text_size, NULL) || + text_size == 0) { + return false; + } + + memset(identifier, 0, kMDGUIDSize); + const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section); + const uint8_t* ptr_end = ptr + std::min(text_size, 4096); + while (ptr < ptr_end) { + for (unsigned i = 0; i < kMDGUIDSize; i++) identifier[i] ^= ptr[i]; + ptr += kMDGUIDSize; + } + return true; +} + +// static +bool FileID::ElfFileIdentifierFromMappedFile(const void* base, + uint8_t identifier[kMDGUIDSize]) { + // Look for a build id note first. + if (FindElfBuildIDNote(base, identifier)) return true; + + // Fall back on hashing the first page of the text section. + return HashElfTextSection(base, identifier); +} + +// static +void FileID::ConvertIdentifierToString(const uint8_t identifier[kMDGUIDSize], + char* buffer, int buffer_length) { + uint8_t identifier_swapped[kMDGUIDSize]; + + // Endian-ness swap to match dump processor expectation. + memcpy(identifier_swapped, identifier, kMDGUIDSize); + uint32_t* data1 = reinterpret_cast<uint32_t*>(identifier_swapped); + *data1 = htonl(*data1); + uint16_t* data2 = reinterpret_cast<uint16_t*>(identifier_swapped + 4); + *data2 = htons(*data2); + uint16_t* data3 = reinterpret_cast<uint16_t*>(identifier_swapped + 6); + *data3 = htons(*data3); + + int buffer_idx = 0; + for (unsigned int idx = 0; + (buffer_idx < buffer_length) && (idx < kMDGUIDSize); ++idx) { + int hi = (identifier_swapped[idx] >> 4) & 0x0F; + int lo = (identifier_swapped[idx]) & 0x0F; + + if (idx == 4 || idx == 6 || idx == 8 || idx == 10) + buffer[buffer_idx++] = '-'; + + buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi; + buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo; + } + + // NULL terminate + buffer[(buffer_idx < buffer_length) ? buffer_idx : buffer_idx - 1] = 0; +} + +} // namespace lul |