// 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. // CFI reader author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com> // Implementation of dwarf2reader::LineInfo, dwarf2reader::CompilationUnit, // and dwarf2reader::CallFrameInfo. See dwarf2reader.h for details. #include "common/dwarf/dwarf2reader.h" #include <assert.h> #include <stdint.h> #include <stdio.h> #include <string.h> #include <map> #include <memory> #include <stack> #include <string> #include <utility> #include "common/dwarf/bytereader-inl.h" #include "common/dwarf/bytereader.h" #include "common/dwarf/line_state_machine.h" #include "common/using_std_string.h" namespace dwarf2reader { CompilationUnit::CompilationUnit(const SectionMap& sections, uint64 offset, ByteReader* reader, Dwarf2Handler* handler) : offset_from_section_start_(offset), reader_(reader), sections_(sections), handler_(handler), abbrevs_(NULL), string_buffer_(NULL), string_buffer_length_(0) {} // Read a DWARF2/3 abbreviation section. // Each abbrev consists of a abbreviation number, a tag, a byte // specifying whether the tag has children, and a list of // attribute/form pairs. // The list of forms is terminated by a 0 for the attribute, and a // zero for the form. The entire abbreviation section is terminated // by a zero for the code. void CompilationUnit::ReadAbbrevs() { if (abbrevs_) return; // First get the debug_abbrev section. ".debug_abbrev" is the name // recommended in the DWARF spec, and used on Linux; // "__debug_abbrev" is the name used in Mac OS X Mach-O files. SectionMap::const_iterator iter = sections_.find(".debug_abbrev"); if (iter == sections_.end()) iter = sections_.find("__debug_abbrev"); assert(iter != sections_.end()); abbrevs_ = new std::vector<Abbrev>; abbrevs_->resize(1); // The only way to check whether we are reading over the end of the // buffer would be to first compute the size of the leb128 data by // reading it, then go back and read it again. const char* abbrev_start = iter->second.first + header_.abbrev_offset; const char* abbrevptr = abbrev_start; #ifndef NDEBUG const uint64 abbrev_length = iter->second.second - header_.abbrev_offset; #endif while (1) { CompilationUnit::Abbrev abbrev; size_t len; const uint64 number = reader_->ReadUnsignedLEB128(abbrevptr, &len); if (number == 0) break; abbrev.number = number; abbrevptr += len; assert(abbrevptr < abbrev_start + abbrev_length); const uint64 tag = reader_->ReadUnsignedLEB128(abbrevptr, &len); abbrevptr += len; abbrev.tag = static_cast<enum DwarfTag>(tag); assert(abbrevptr < abbrev_start + abbrev_length); abbrev.has_children = reader_->ReadOneByte(abbrevptr); abbrevptr += 1; assert(abbrevptr < abbrev_start + abbrev_length); while (1) { const uint64 nametemp = reader_->ReadUnsignedLEB128(abbrevptr, &len); abbrevptr += len; assert(abbrevptr < abbrev_start + abbrev_length); const uint64 formtemp = reader_->ReadUnsignedLEB128(abbrevptr, &len); abbrevptr += len; if (nametemp == 0 && formtemp == 0) break; const enum DwarfAttribute name = static_cast<enum DwarfAttribute>(nametemp); const enum DwarfForm form = static_cast<enum DwarfForm>(formtemp); abbrev.attributes.push_back(std::make_pair(name, form)); } assert(abbrev.number == abbrevs_->size()); abbrevs_->push_back(abbrev); } } // Skips a single DIE's attributes. const char* CompilationUnit::SkipDIE(const char* start, const Abbrev& abbrev) { for (AttributeList::const_iterator i = abbrev.attributes.begin(); i != abbrev.attributes.end(); i++) { start = SkipAttribute(start, i->second); } return start; } // Skips a single attribute form's data. const char* CompilationUnit::SkipAttribute(const char* start, enum DwarfForm form) { size_t len; switch (form) { case DW_FORM_indirect: form = static_cast<enum DwarfForm>(reader_->ReadUnsignedLEB128(start, &len)); start += len; return SkipAttribute(start, form); case DW_FORM_flag_present: return start; case DW_FORM_data1: case DW_FORM_flag: case DW_FORM_ref1: return start + 1; case DW_FORM_ref2: case DW_FORM_data2: return start + 2; case DW_FORM_ref4: case DW_FORM_data4: return start + 4; case DW_FORM_ref8: case DW_FORM_data8: case DW_FORM_ref_sig8: return start + 8; case DW_FORM_string: return start + strlen(start) + 1; case DW_FORM_udata: case DW_FORM_ref_udata: reader_->ReadUnsignedLEB128(start, &len); return start + len; case DW_FORM_sdata: reader_->ReadSignedLEB128(start, &len); return start + len; case DW_FORM_addr: return start + reader_->AddressSize(); case DW_FORM_ref_addr: // DWARF2 and 3/4 differ on whether ref_addr is address size or // offset size. assert(header_.version >= 2); if (header_.version == 2) { return start + reader_->AddressSize(); } else if (header_.version >= 3) { return start + reader_->OffsetSize(); } break; case DW_FORM_block1: return start + 1 + reader_->ReadOneByte(start); case DW_FORM_block2: return start + 2 + reader_->ReadTwoBytes(start); case DW_FORM_block4: return start + 4 + reader_->ReadFourBytes(start); case DW_FORM_block: case DW_FORM_exprloc: { uint64 size = reader_->ReadUnsignedLEB128(start, &len); return start + size + len; } case DW_FORM_strp: case DW_FORM_sec_offset: return start + reader_->OffsetSize(); } fprintf(stderr,"Unhandled form type"); return NULL; } // Read a DWARF2/3 header. // The header is variable length in DWARF3 (and DWARF2 as extended by // most compilers), and consists of an length field, a version number, // the offset in the .debug_abbrev section for our abbrevs, and an // address size. void CompilationUnit::ReadHeader() { const char* headerptr = buffer_; size_t initial_length_size; assert(headerptr + 4 < buffer_ + buffer_length_); const uint64 initial_length = reader_->ReadInitialLength(headerptr, &initial_length_size); headerptr += initial_length_size; header_.length = initial_length; assert(headerptr + 2 < buffer_ + buffer_length_); header_.version = reader_->ReadTwoBytes(headerptr); headerptr += 2; assert(headerptr + reader_->OffsetSize() < buffer_ + buffer_length_); header_.abbrev_offset = reader_->ReadOffset(headerptr); headerptr += reader_->OffsetSize(); assert(headerptr + 1 < buffer_ + buffer_length_); header_.address_size = reader_->ReadOneByte(headerptr); reader_->SetAddressSize(header_.address_size); headerptr += 1; after_header_ = headerptr; // This check ensures that we don't have to do checking during the // reading of DIEs. header_.length does not include the size of the // initial length. assert(buffer_ + initial_length_size + header_.length <= buffer_ + buffer_length_); } uint64 CompilationUnit::Start() { // First get the debug_info section. ".debug_info" is the name // recommended in the DWARF spec, and used on Linux; "__debug_info" // is the name used in Mac OS X Mach-O files. SectionMap::const_iterator iter = sections_.find(".debug_info"); if (iter == sections_.end()) iter = sections_.find("__debug_info"); assert(iter != sections_.end()); // Set up our buffer buffer_ = iter->second.first + offset_from_section_start_; buffer_length_ = iter->second.second - offset_from_section_start_; // Read the header ReadHeader(); // Figure out the real length from the end of the initial length to // the end of the compilation unit, since that is the value we // return. uint64 ourlength = header_.length; if (reader_->OffsetSize() == 8) ourlength += 12; else ourlength += 4; // See if the user wants this compilation unit, and if not, just return. if (!handler_->StartCompilationUnit(offset_from_section_start_, reader_->AddressSize(), reader_->OffsetSize(), header_.length, header_.version)) return ourlength; // Otherwise, continue by reading our abbreviation entries. ReadAbbrevs(); // Set the string section if we have one. ".debug_str" is the name // recommended in the DWARF spec, and used on Linux; "__debug_str" // is the name used in Mac OS X Mach-O files. iter = sections_.find(".debug_str"); if (iter == sections_.end()) iter = sections_.find("__debug_str"); if (iter != sections_.end()) { string_buffer_ = iter->second.first; string_buffer_length_ = iter->second.second; } // Now that we have our abbreviations, start processing DIE's. ProcessDIEs(); return ourlength; } // If one really wanted, you could merge SkipAttribute and // ProcessAttribute // This is all boring data manipulation and calling of the handler. const char* CompilationUnit::ProcessAttribute( uint64 dieoffset, const char* start, enum DwarfAttribute attr, enum DwarfForm form) { size_t len; switch (form) { // DW_FORM_indirect is never used because it is such a space // waster. case DW_FORM_indirect: form = static_cast<enum DwarfForm>(reader_->ReadUnsignedLEB128(start, &len)); start += len; return ProcessAttribute(dieoffset, start, attr, form); case DW_FORM_flag_present: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, 1); return start; case DW_FORM_data1: case DW_FORM_flag: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadOneByte(start)); return start + 1; case DW_FORM_data2: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadTwoBytes(start)); return start + 2; case DW_FORM_data4: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadFourBytes(start)); return start + 4; case DW_FORM_data8: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadEightBytes(start)); return start + 8; case DW_FORM_string: { const char* str = start; handler_->ProcessAttributeString(dieoffset, attr, form, str); return start + strlen(str) + 1; } case DW_FORM_udata: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadUnsignedLEB128(start, &len)); return start + len; case DW_FORM_sdata: handler_->ProcessAttributeSigned(dieoffset, attr, form, reader_->ReadSignedLEB128(start, &len)); return start + len; case DW_FORM_addr: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadAddress(start)); return start + reader_->AddressSize(); case DW_FORM_sec_offset: handler_->ProcessAttributeUnsigned(dieoffset, attr, form, reader_->ReadOffset(start)); return start + reader_->OffsetSize(); case DW_FORM_ref1: handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadOneByte(start) + offset_from_section_start_); return start + 1; case DW_FORM_ref2: handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadTwoBytes(start) + offset_from_section_start_); return start + 2; case DW_FORM_ref4: handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadFourBytes(start) + offset_from_section_start_); return start + 4; case DW_FORM_ref8: handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadEightBytes(start) + offset_from_section_start_); return start + 8; case DW_FORM_ref_udata: handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadUnsignedLEB128(start, &len) + offset_from_section_start_); return start + len; case DW_FORM_ref_addr: // DWARF2 and 3/4 differ on whether ref_addr is address size or // offset size. assert(header_.version >= 2); if (header_.version == 2) { handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadAddress(start)); return start + reader_->AddressSize(); } else if (header_.version >= 3) { handler_->ProcessAttributeReference(dieoffset, attr, form, reader_->ReadOffset(start)); return start + reader_->OffsetSize(); } break; case DW_FORM_ref_sig8: handler_->ProcessAttributeSignature(dieoffset, attr, form, reader_->ReadEightBytes(start)); return start + 8; case DW_FORM_block1: { uint64 datalen = reader_->ReadOneByte(start); handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 1, datalen); return start + 1 + datalen; } case DW_FORM_block2: { uint64 datalen = reader_->ReadTwoBytes(start); handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 2, datalen); return start + 2 + datalen; } case DW_FORM_block4: { uint64 datalen = reader_->ReadFourBytes(start); handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 4, datalen); return start + 4 + datalen; } case DW_FORM_block: case DW_FORM_exprloc: { uint64 datalen = reader_->ReadUnsignedLEB128(start, &len); handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + len, datalen); return start + datalen + len; } case DW_FORM_strp: { assert(string_buffer_ != NULL); const uint64 offset = reader_->ReadOffset(start); assert(string_buffer_ + offset < string_buffer_ + string_buffer_length_); const char* str = string_buffer_ + offset; handler_->ProcessAttributeString(dieoffset, attr, form, str); return start + reader_->OffsetSize(); } } fprintf(stderr, "Unhandled form type\n"); return NULL; } const char* CompilationUnit::ProcessDIE(uint64 dieoffset, const char* start, const Abbrev& abbrev) { for (AttributeList::const_iterator i = abbrev.attributes.begin(); i != abbrev.attributes.end(); i++) { start = ProcessAttribute(dieoffset, start, i->first, i->second); } return start; } void CompilationUnit::ProcessDIEs() { const char* dieptr = after_header_; size_t len; // lengthstart is the place the length field is based on. // It is the point in the header after the initial length field const char* lengthstart = buffer_; // In 64 bit dwarf, the initial length is 12 bytes, because of the // 0xffffffff at the start. if (reader_->OffsetSize() == 8) lengthstart += 12; else lengthstart += 4; std::stack<uint64> die_stack; while (dieptr < (lengthstart + header_.length)) { // We give the user the absolute offset from the beginning of // debug_info, since they need it to deal with ref_addr forms. uint64 absolute_offset = (dieptr - buffer_) + offset_from_section_start_; uint64 abbrev_num = reader_->ReadUnsignedLEB128(dieptr, &len); dieptr += len; // Abbrev == 0 represents the end of a list of children, or padding // at the end of the compilation unit. if (abbrev_num == 0) { if (die_stack.size() == 0) // If it is padding, then we are done with the compilation unit's DIEs. return; const uint64 offset = die_stack.top(); die_stack.pop(); handler_->EndDIE(offset); continue; } const Abbrev& abbrev = abbrevs_->at(static_cast<size_t>(abbrev_num)); const enum DwarfTag tag = abbrev.tag; if (!handler_->StartDIE(absolute_offset, tag)) { dieptr = SkipDIE(dieptr, abbrev); } else { dieptr = ProcessDIE(absolute_offset, dieptr, abbrev); } if (abbrev.has_children) { die_stack.push(absolute_offset); } else { handler_->EndDIE(absolute_offset); } } } LineInfo::LineInfo(const char* buffer, uint64 buffer_length, ByteReader* reader, LineInfoHandler* handler): handler_(handler), reader_(reader), buffer_(buffer), buffer_length_(buffer_length) { header_.std_opcode_lengths = NULL; } uint64 LineInfo::Start() { ReadHeader(); ReadLines(); return after_header_ - buffer_; } // The header for a debug_line section is mildly complicated, because // the line info is very tightly encoded. void LineInfo::ReadHeader() { const char* lineptr = buffer_; size_t initial_length_size; const uint64 initial_length = reader_->ReadInitialLength(lineptr, &initial_length_size); lineptr += initial_length_size; header_.total_length = initial_length; assert(buffer_ + initial_length_size + header_.total_length <= buffer_ + buffer_length_); // Address size *must* be set by CU ahead of time. assert(reader_->AddressSize() != 0); header_.version = reader_->ReadTwoBytes(lineptr); lineptr += 2; header_.prologue_length = reader_->ReadOffset(lineptr); lineptr += reader_->OffsetSize(); header_.min_insn_length = reader_->ReadOneByte(lineptr); lineptr += 1; header_.default_is_stmt = reader_->ReadOneByte(lineptr); lineptr += 1; header_.line_base = *reinterpret_cast<const int8*>(lineptr); lineptr += 1; header_.line_range = reader_->ReadOneByte(lineptr); lineptr += 1; header_.opcode_base = reader_->ReadOneByte(lineptr); lineptr += 1; header_.std_opcode_lengths = new std::vector<unsigned char>; header_.std_opcode_lengths->resize(header_.opcode_base + 1); (*header_.std_opcode_lengths)[0] = 0; for (int i = 1; i < header_.opcode_base; i++) { (*header_.std_opcode_lengths)[i] = reader_->ReadOneByte(lineptr); lineptr += 1; } // It is legal for the directory entry table to be empty. if (*lineptr) { uint32 dirindex = 1; while (*lineptr) { const char* dirname = lineptr; handler_->DefineDir(dirname, dirindex); lineptr += strlen(dirname) + 1; dirindex++; } } lineptr++; // It is also legal for the file entry table to be empty. if (*lineptr) { uint32 fileindex = 1; size_t len; while (*lineptr) { const char* filename = lineptr; lineptr += strlen(filename) + 1; uint64 dirindex = reader_->ReadUnsignedLEB128(lineptr, &len); lineptr += len; uint64 mod_time = reader_->ReadUnsignedLEB128(lineptr, &len); lineptr += len; uint64 filelength = reader_->ReadUnsignedLEB128(lineptr, &len); lineptr += len; handler_->DefineFile(filename, fileindex, static_cast<uint32>(dirindex), mod_time, filelength); fileindex++; } } lineptr++; after_header_ = lineptr; } /* static */ bool LineInfo::ProcessOneOpcode(ByteReader* reader, LineInfoHandler* handler, const struct LineInfoHeader &header, const char* start, struct LineStateMachine* lsm, size_t* len, uintptr pc, bool *lsm_passes_pc) { size_t oplen = 0; size_t templen; uint8 opcode = reader->ReadOneByte(start); oplen++; start++; // If the opcode is great than the opcode_base, it is a special // opcode. Most line programs consist mainly of special opcodes. if (opcode >= header.opcode_base) { opcode -= header.opcode_base; const int64 advance_address = (opcode / header.line_range) * header.min_insn_length; const int32 advance_line = (opcode % header.line_range) + header.line_base; // Check if the lsm passes "pc". If so, mark it as passed. if (lsm_passes_pc && lsm->address <= pc && pc < lsm->address + advance_address) { *lsm_passes_pc = true; } lsm->address += advance_address; lsm->line_num += advance_line; lsm->basic_block = true; *len = oplen; return true; } // Otherwise, we have the regular opcodes switch (opcode) { case DW_LNS_copy: { lsm->basic_block = false; *len = oplen; return true; } case DW_LNS_advance_pc: { uint64 advance_address = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; // Check if the lsm passes "pc". If so, mark it as passed. if (lsm_passes_pc && lsm->address <= pc && pc < lsm->address + header.min_insn_length * advance_address) { *lsm_passes_pc = true; } lsm->address += header.min_insn_length * advance_address; } break; case DW_LNS_advance_line: { const int64 advance_line = reader->ReadSignedLEB128(start, &templen); oplen += templen; lsm->line_num += static_cast<int32>(advance_line); // With gcc 4.2.1, we can get the line_no here for the first time // since DW_LNS_advance_line is called after DW_LNE_set_address is // called. So we check if the lsm passes "pc" here, not in // DW_LNE_set_address. if (lsm_passes_pc && lsm->address == pc) { *lsm_passes_pc = true; } } break; case DW_LNS_set_file: { const uint64 fileno = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; lsm->file_num = static_cast<uint32>(fileno); } break; case DW_LNS_set_column: { const uint64 colno = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; lsm->column_num = static_cast<uint32>(colno); } break; case DW_LNS_negate_stmt: { lsm->is_stmt = !lsm->is_stmt; } break; case DW_LNS_set_basic_block: { lsm->basic_block = true; } break; case DW_LNS_fixed_advance_pc: { const uint16 advance_address = reader->ReadTwoBytes(start); oplen += 2; // Check if the lsm passes "pc". If so, mark it as passed. if (lsm_passes_pc && lsm->address <= pc && pc < lsm->address + advance_address) { *lsm_passes_pc = true; } lsm->address += advance_address; } break; case DW_LNS_const_add_pc: { const int64 advance_address = header.min_insn_length * ((255 - header.opcode_base) / header.line_range); // Check if the lsm passes "pc". If so, mark it as passed. if (lsm_passes_pc && lsm->address <= pc && pc < lsm->address + advance_address) { *lsm_passes_pc = true; } lsm->address += advance_address; } break; case DW_LNS_extended_op: { const uint64 extended_op_len = reader->ReadUnsignedLEB128(start, &templen); start += templen; oplen += templen + extended_op_len; const uint64 extended_op = reader->ReadOneByte(start); start++; switch (extended_op) { case DW_LNE_end_sequence: { lsm->end_sequence = true; *len = oplen; return true; } break; case DW_LNE_set_address: { // With gcc 4.2.1, we cannot tell the line_no here since // DW_LNE_set_address is called before DW_LNS_advance_line is // called. So we do not check if the lsm passes "pc" here. See // also the comment in DW_LNS_advance_line. uint64 address = reader->ReadAddress(start); lsm->address = address; } break; case DW_LNE_define_file: { const char* filename = start; templen = strlen(filename) + 1; start += templen; uint64 dirindex = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; const uint64 mod_time = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; const uint64 filelength = reader->ReadUnsignedLEB128(start, &templen); oplen += templen; if (handler) { handler->DefineFile(filename, -1, static_cast<uint32>(dirindex), mod_time, filelength); } } break; } } break; default: { // Ignore unknown opcode silently if (header.std_opcode_lengths) { for (int i = 0; i < (*header.std_opcode_lengths)[opcode]; i++) { reader->ReadUnsignedLEB128(start, &templen); start += templen; oplen += templen; } } } break; } *len = oplen; return false; } void LineInfo::ReadLines() { struct LineStateMachine lsm; // lengthstart is the place the length field is based on. // It is the point in the header after the initial length field const char* lengthstart = buffer_; // In 64 bit dwarf, the initial length is 12 bytes, because of the // 0xffffffff at the start. if (reader_->OffsetSize() == 8) lengthstart += 12; else lengthstart += 4; const char* lineptr = after_header_; lsm.Reset(header_.default_is_stmt); // The LineInfoHandler interface expects each line's length along // with its address, but DWARF only provides addresses (sans // length), and an end-of-sequence address; one infers the length // from the next address. So we report a line only when we get the // next line's address, or the end-of-sequence address. bool have_pending_line = false; uint64 pending_address = 0; uint32 pending_file_num = 0, pending_line_num = 0, pending_column_num = 0; while (lineptr < lengthstart + header_.total_length) { size_t oplength; bool add_row = ProcessOneOpcode(reader_, handler_, header_, lineptr, &lsm, &oplength, (uintptr)-1, NULL); if (add_row) { if (have_pending_line) handler_->AddLine(pending_address, lsm.address - pending_address, pending_file_num, pending_line_num, pending_column_num); if (lsm.end_sequence) { lsm.Reset(header_.default_is_stmt); have_pending_line = false; } else { pending_address = lsm.address; pending_file_num = lsm.file_num; pending_line_num = lsm.line_num; pending_column_num = lsm.column_num; have_pending_line = true; } } lineptr += oplength; } after_header_ = lengthstart + header_.total_length; } // A DWARF rule for recovering the address or value of a register, or // computing the canonical frame address. There is one subclass of this for // each '*Rule' member function in CallFrameInfo::Handler. // // It's annoying that we have to handle Rules using pointers (because // the concrete instances can have an arbitrary size). They're small, // so it would be much nicer if we could just handle them by value // instead of fretting about ownership and destruction. // // It seems like all these could simply be instances of std::tr1::bind, // except that we need instances to be EqualityComparable, too. // // This could logically be nested within State, but then the qualified names // get horrendous. class CallFrameInfo::Rule { public: virtual ~Rule() { } // Tell HANDLER that, at ADDRESS in the program, REGISTER can be // recovered using this rule. If REGISTER is kCFARegister, then this rule // describes how to compute the canonical frame address. Return what the // HANDLER member function returned. virtual bool Handle(Handler *handler, uint64 address, int register) const = 0; // Equality on rules. We use these to decide which rules we need // to report after a DW_CFA_restore_state instruction. virtual bool operator==(const Rule &rhs) const = 0; bool operator!=(const Rule &rhs) const { return ! (*this == rhs); } // Return a pointer to a copy of this rule. virtual Rule *Copy() const = 0; // If this is a base+offset rule, change its base register to REG. // Otherwise, do nothing. (Ugly, but required for DW_CFA_def_cfa_register.) virtual void SetBaseRegister(unsigned reg) { } // If this is a base+offset rule, change its offset to OFFSET. Otherwise, // do nothing. (Ugly, but required for DW_CFA_def_cfa_offset.) virtual void SetOffset(long long offset) { } }; // Rule: the value the register had in the caller cannot be recovered. class CallFrameInfo::UndefinedRule: public CallFrameInfo::Rule { public: UndefinedRule() { } ~UndefinedRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->UndefinedRule(address, reg); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const UndefinedRule *our_rhs = dynamic_cast<const UndefinedRule *>(&rhs); return (our_rhs != NULL); } Rule *Copy() const { return new UndefinedRule(*this); } }; // Rule: the register's value is the same as that it had in the caller. class CallFrameInfo::SameValueRule: public CallFrameInfo::Rule { public: SameValueRule() { } ~SameValueRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->SameValueRule(address, reg); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const SameValueRule *our_rhs = dynamic_cast<const SameValueRule *>(&rhs); return (our_rhs != NULL); } Rule *Copy() const { return new SameValueRule(*this); } }; // Rule: the register is saved at OFFSET from BASE_REGISTER. BASE_REGISTER // may be CallFrameInfo::Handler::kCFARegister. class CallFrameInfo::OffsetRule: public CallFrameInfo::Rule { public: OffsetRule(int base_register, long offset) : base_register_(base_register), offset_(offset) { } ~OffsetRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->OffsetRule(address, reg, base_register_, offset_); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const OffsetRule *our_rhs = dynamic_cast<const OffsetRule *>(&rhs); return (our_rhs && base_register_ == our_rhs->base_register_ && offset_ == our_rhs->offset_); } Rule *Copy() const { return new OffsetRule(*this); } // We don't actually need SetBaseRegister or SetOffset here, since they // are only ever applied to CFA rules, for DW_CFA_def_cfa_offset, and it // doesn't make sense to use OffsetRule for computing the CFA: it // computes the address at which a register is saved, not a value. private: int base_register_; long offset_; }; // Rule: the value the register had in the caller is the value of // BASE_REGISTER plus offset. BASE_REGISTER may be // CallFrameInfo::Handler::kCFARegister. class CallFrameInfo::ValOffsetRule: public CallFrameInfo::Rule { public: ValOffsetRule(int base_register, long offset) : base_register_(base_register), offset_(offset) { } ~ValOffsetRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->ValOffsetRule(address, reg, base_register_, offset_); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const ValOffsetRule *our_rhs = dynamic_cast<const ValOffsetRule *>(&rhs); return (our_rhs && base_register_ == our_rhs->base_register_ && offset_ == our_rhs->offset_); } Rule *Copy() const { return new ValOffsetRule(*this); } void SetBaseRegister(unsigned reg) { base_register_ = reg; } void SetOffset(long long offset) { offset_ = offset; } private: int base_register_; long offset_; }; // Rule: the register has been saved in another register REGISTER_NUMBER_. class CallFrameInfo::RegisterRule: public CallFrameInfo::Rule { public: explicit RegisterRule(int register_number) : register_number_(register_number) { } ~RegisterRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->RegisterRule(address, reg, register_number_); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const RegisterRule *our_rhs = dynamic_cast<const RegisterRule *>(&rhs); return (our_rhs && register_number_ == our_rhs->register_number_); } Rule *Copy() const { return new RegisterRule(*this); } private: int register_number_; }; // Rule: EXPRESSION evaluates to the address at which the register is saved. class CallFrameInfo::ExpressionRule: public CallFrameInfo::Rule { public: explicit ExpressionRule(const string &expression) : expression_(expression) { } ~ExpressionRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->ExpressionRule(address, reg, expression_); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const ExpressionRule *our_rhs = dynamic_cast<const ExpressionRule *>(&rhs); return (our_rhs && expression_ == our_rhs->expression_); } Rule *Copy() const { return new ExpressionRule(*this); } private: string expression_; }; // Rule: EXPRESSION evaluates to the address at which the register is saved. class CallFrameInfo::ValExpressionRule: public CallFrameInfo::Rule { public: explicit ValExpressionRule(const string &expression) : expression_(expression) { } ~ValExpressionRule() { } bool Handle(Handler *handler, uint64 address, int reg) const { return handler->ValExpressionRule(address, reg, expression_); } bool operator==(const Rule &rhs) const { // dynamic_cast is allowed by the Google C++ Style Guide, if the use has // been carefully considered; cheap RTTI-like workarounds are forbidden. const ValExpressionRule *our_rhs = dynamic_cast<const ValExpressionRule *>(&rhs); return (our_rhs && expression_ == our_rhs->expression_); } Rule *Copy() const { return new ValExpressionRule(*this); } private: string expression_; }; // A map from register numbers to rules. class CallFrameInfo::RuleMap { public: RuleMap() : cfa_rule_(NULL) { } RuleMap(const RuleMap &rhs) : cfa_rule_(NULL) { *this = rhs; } ~RuleMap() { Clear(); } RuleMap &operator=(const RuleMap &rhs); // Set the rule for computing the CFA to RULE. Take ownership of RULE. void SetCFARule(Rule *rule) { delete cfa_rule_; cfa_rule_ = rule; } // Return the current CFA rule. Unlike RegisterRule, this RuleMap retains // ownership of the rule. We use this for DW_CFA_def_cfa_offset and // DW_CFA_def_cfa_register, and for detecting references to the CFA before // a rule for it has been established. Rule *CFARule() const { return cfa_rule_; } // Return the rule for REG, or NULL if there is none. The caller takes // ownership of the result. Rule *RegisterRule(int reg) const; // Set the rule for computing REG to RULE. Take ownership of RULE. void SetRegisterRule(int reg, Rule *rule); // Make all the appropriate calls to HANDLER as if we were changing from // this RuleMap to NEW_RULES at ADDRESS. We use this to implement // DW_CFA_restore_state, where lots of rules can change simultaneously. // Return true if all handlers returned true; otherwise, return false. bool HandleTransitionTo(Handler *handler, uint64 address, const RuleMap &new_rules) const; private: // A map from register numbers to Rules. typedef std::map<int, Rule *> RuleByNumber; // Remove all register rules and clear cfa_rule_. void Clear(); // The rule for computing the canonical frame address. This RuleMap owns // this rule. Rule *cfa_rule_; // A map from register numbers to postfix expressions to recover // their values. This RuleMap owns the Rules the map refers to. RuleByNumber registers_; }; CallFrameInfo::RuleMap &CallFrameInfo::RuleMap::operator=(const RuleMap &rhs) { Clear(); // Since each map owns the rules it refers to, assignment must copy them. if (rhs.cfa_rule_) cfa_rule_ = rhs.cfa_rule_->Copy(); for (RuleByNumber::const_iterator it = rhs.registers_.begin(); it != rhs.registers_.end(); it++) registers_[it->first] = it->second->Copy(); return *this; } CallFrameInfo::Rule *CallFrameInfo::RuleMap::RegisterRule(int reg) const { assert(reg != Handler::kCFARegister); RuleByNumber::const_iterator it = registers_.find(reg); if (it != registers_.end()) return it->second->Copy(); else return NULL; } void CallFrameInfo::RuleMap::SetRegisterRule(int reg, Rule *rule) { assert(reg != Handler::kCFARegister); assert(rule); Rule **slot = ®isters_[reg]; delete *slot; *slot = rule; } bool CallFrameInfo::RuleMap::HandleTransitionTo( Handler *handler, uint64 address, const RuleMap &new_rules) const { // Transition from cfa_rule_ to new_rules.cfa_rule_. if (cfa_rule_ && new_rules.cfa_rule_) { if (*cfa_rule_ != *new_rules.cfa_rule_ && !new_rules.cfa_rule_->Handle(handler, address, Handler::kCFARegister)) return false; } else if (cfa_rule_) { // this RuleMap has a CFA rule but new_rules doesn't. // CallFrameInfo::Handler has no way to handle this --- and shouldn't; // it's garbage input. The instruction interpreter should have // detected this and warned, so take no action here. } else if (new_rules.cfa_rule_) { // This shouldn't be possible: NEW_RULES is some prior state, and // there's no way to remove entries. assert(0); } else { // Both CFA rules are empty. No action needed. } // Traverse the two maps in order by register number, and report // whatever differences we find. RuleByNumber::const_iterator old_it = registers_.begin(); RuleByNumber::const_iterator new_it = new_rules.registers_.begin(); while (old_it != registers_.end() && new_it != new_rules.registers_.end()) { if (old_it->first < new_it->first) { // This RuleMap has an entry for old_it->first, but NEW_RULES // doesn't. // // This isn't really the right thing to do, but since CFI generally // only mentions callee-saves registers, and GCC's convention for // callee-saves registers is that they are unchanged, it's a good // approximation. if (!handler->SameValueRule(address, old_it->first)) return false; old_it++; } else if (old_it->first > new_it->first) { // NEW_RULES has entry for new_it->first, but this RuleMap // doesn't. This shouldn't be possible: NEW_RULES is some prior // state, and there's no way to remove entries. assert(0); } else { // Both maps have an entry for this register. Report the new // rule if it is different. if (*old_it->second != *new_it->second && !new_it->second->Handle(handler, address, new_it->first)) return false; new_it++, old_it++; } } // Finish off entries from this RuleMap with no counterparts in new_rules. while (old_it != registers_.end()) { if (!handler->SameValueRule(address, old_it->first)) return false; old_it++; } // Since we only make transitions from a rule set to some previously // saved rule set, and we can only add rules to the map, NEW_RULES // must have fewer rules than *this. assert(new_it == new_rules.registers_.end()); return true; } // Remove all register rules and clear cfa_rule_. void CallFrameInfo::RuleMap::Clear() { delete cfa_rule_; cfa_rule_ = NULL; for (RuleByNumber::iterator it = registers_.begin(); it != registers_.end(); it++) delete it->second; registers_.clear(); } // The state of the call frame information interpreter as it processes // instructions from a CIE and FDE. class CallFrameInfo::State { public: // Create a call frame information interpreter state with the given // reporter, reader, handler, and initial call frame info address. State(ByteReader *reader, Handler *handler, Reporter *reporter, uint64 address) : reader_(reader), handler_(handler), reporter_(reporter), address_(address), entry_(NULL), cursor_(NULL) { } // Interpret instructions from CIE, save the resulting rule set for // DW_CFA_restore instructions, and return true. On error, report // the problem to reporter_ and return false. bool InterpretCIE(const CIE &cie); // Interpret instructions from FDE, and return true. On error, // report the problem to reporter_ and return false. bool InterpretFDE(const FDE &fde); private: // The operands of a CFI instruction, for ParseOperands. struct Operands { unsigned register_number; // A register number. uint64 offset; // An offset or address. long signed_offset; // A signed offset. string expression; // A DWARF expression. }; // Parse CFI instruction operands from STATE's instruction stream as // described by FORMAT. On success, populate OPERANDS with the // results, and return true. On failure, report the problem and // return false. // // Each character of FORMAT should be one of the following: // // 'r' unsigned LEB128 register number (OPERANDS->register_number) // 'o' unsigned LEB128 offset (OPERANDS->offset) // 's' signed LEB128 offset (OPERANDS->signed_offset) // 'a' machine-size address (OPERANDS->offset) // (If the CIE has a 'z' augmentation string, 'a' uses the // encoding specified by the 'R' argument.) // '1' a one-byte offset (OPERANDS->offset) // '2' a two-byte offset (OPERANDS->offset) // '4' a four-byte offset (OPERANDS->offset) // '8' an eight-byte offset (OPERANDS->offset) // 'e' a DW_FORM_block holding a (OPERANDS->expression) // DWARF expression bool ParseOperands(const char *format, Operands *operands); // Interpret one CFI instruction from STATE's instruction stream, update // STATE, report any rule changes to handler_, and return true. On // failure, report the problem and return false. bool DoInstruction(); // The following Do* member functions are subroutines of DoInstruction, // factoring out the actual work of operations that have several // different encodings. // Set the CFA rule to be the value of BASE_REGISTER plus OFFSET, and // return true. On failure, report and return false. (Used for // DW_CFA_def_cfa and DW_CFA_def_cfa_sf.) bool DoDefCFA(unsigned base_register, long offset); // Change the offset of the CFA rule to OFFSET, and return true. On // failure, report and return false. (Subroutine for // DW_CFA_def_cfa_offset and DW_CFA_def_cfa_offset_sf.) bool DoDefCFAOffset(long offset); // Specify that REG can be recovered using RULE, and return true. On // failure, report and return false. bool DoRule(unsigned reg, Rule *rule); // Specify that REG can be found at OFFSET from the CFA, and return true. // On failure, report and return false. (Subroutine for DW_CFA_offset, // DW_CFA_offset_extended, and DW_CFA_offset_extended_sf.) bool DoOffset(unsigned reg, long offset); // Specify that the caller's value for REG is the CFA plus OFFSET, // and return true. On failure, report and return false. (Subroutine // for DW_CFA_val_offset and DW_CFA_val_offset_sf.) bool DoValOffset(unsigned reg, long offset); // Restore REG to the rule established in the CIE, and return true. On // failure, report and return false. (Subroutine for DW_CFA_restore and // DW_CFA_restore_extended.) bool DoRestore(unsigned reg); // Return the section offset of the instruction at cursor. For use // in error messages. uint64 CursorOffset() { return entry_->offset + (cursor_ - entry_->start); } // Report that entry_ is incomplete, and return false. For brevity. bool ReportIncomplete() { reporter_->Incomplete(entry_->offset, entry_->kind); return false; } // For reading multi-byte values with the appropriate endianness. ByteReader *reader_; // The handler to which we should report the data we find. Handler *handler_; // For reporting problems in the info we're parsing. Reporter *reporter_; // The code address to which the next instruction in the stream applies. uint64 address_; // The entry whose instructions we are currently processing. This is // first a CIE, and then an FDE. const Entry *entry_; // The next instruction to process. const char *cursor_; // The current set of rules. RuleMap rules_; // The set of rules established by the CIE, used by DW_CFA_restore // and DW_CFA_restore_extended. We set this after interpreting the // CIE's instructions. RuleMap cie_rules_; // A stack of saved states, for DW_CFA_remember_state and // DW_CFA_restore_state. std::stack<RuleMap> saved_rules_; }; bool CallFrameInfo::State::InterpretCIE(const CIE &cie) { entry_ = &cie; cursor_ = entry_->instructions; while (cursor_ < entry_->end) if (!DoInstruction()) return false; // Note the rules established by the CIE, for use by DW_CFA_restore // and DW_CFA_restore_extended. cie_rules_ = rules_; return true; } bool CallFrameInfo::State::InterpretFDE(const FDE &fde) { entry_ = &fde; cursor_ = entry_->instructions; while (cursor_ < entry_->end) if (!DoInstruction()) return false; return true; } bool CallFrameInfo::State::ParseOperands(const char *format, Operands *operands) { size_t len; const char *operand; for (operand = format; *operand; operand++) { size_t bytes_left = entry_->end - cursor_; switch (*operand) { case 'r': operands->register_number = reader_->ReadUnsignedLEB128(cursor_, &len); if (len > bytes_left) return ReportIncomplete(); cursor_ += len; break; case 'o': operands->offset = reader_->ReadUnsignedLEB128(cursor_, &len); if (len > bytes_left) return ReportIncomplete(); cursor_ += len; break; case 's': operands->signed_offset = reader_->ReadSignedLEB128(cursor_, &len); if (len > bytes_left) return ReportIncomplete(); cursor_ += len; break; case 'a': operands->offset = reader_->ReadEncodedPointer(cursor_, entry_->cie->pointer_encoding, &len); if (len > bytes_left) return ReportIncomplete(); cursor_ += len; break; case '1': if (1 > bytes_left) return ReportIncomplete(); operands->offset = static_cast<unsigned char>(*cursor_++); break; case '2': if (2 > bytes_left) return ReportIncomplete(); operands->offset = reader_->ReadTwoBytes(cursor_); cursor_ += 2; break; case '4': if (4 > bytes_left) return ReportIncomplete(); operands->offset = reader_->ReadFourBytes(cursor_); cursor_ += 4; break; case '8': if (8 > bytes_left) return ReportIncomplete(); operands->offset = reader_->ReadEightBytes(cursor_); cursor_ += 8; break; case 'e': { size_t expression_length = reader_->ReadUnsignedLEB128(cursor_, &len); if (len > bytes_left || expression_length > bytes_left - len) return ReportIncomplete(); cursor_ += len; operands->expression = string(cursor_, expression_length); cursor_ += expression_length; break; } default: assert(0); } } return true; } bool CallFrameInfo::State::DoInstruction() { CIE *cie = entry_->cie; Operands ops; // Our entry's kind should have been set by now. assert(entry_->kind != kUnknown); // We shouldn't have been invoked unless there were more // instructions to parse. assert(cursor_ < entry_->end); unsigned opcode = *cursor_++; if ((opcode & 0xc0) != 0) { switch (opcode & 0xc0) { // Advance the address. case DW_CFA_advance_loc: { size_t code_offset = opcode & 0x3f; address_ += code_offset * cie->code_alignment_factor; break; } // Find a register at an offset from the CFA. case DW_CFA_offset: if (!ParseOperands("o", &ops) || !DoOffset(opcode & 0x3f, ops.offset * cie->data_alignment_factor)) return false; break; // Restore the rule established for a register by the CIE. case DW_CFA_restore: if (!DoRestore(opcode & 0x3f)) return false; break; // The 'if' above should have excluded this possibility. default: assert(0); } // Return here, so the big switch below won't be indented. return true; } switch (opcode) { // Set the address. case DW_CFA_set_loc: if (!ParseOperands("a", &ops)) return false; address_ = ops.offset; break; // Advance the address. case DW_CFA_advance_loc1: if (!ParseOperands("1", &ops)) return false; address_ += ops.offset * cie->code_alignment_factor; break; // Advance the address. case DW_CFA_advance_loc2: if (!ParseOperands("2", &ops)) return false; address_ += ops.offset * cie->code_alignment_factor; break; // Advance the address. case DW_CFA_advance_loc4: if (!ParseOperands("4", &ops)) return false; address_ += ops.offset * cie->code_alignment_factor; break; // Advance the address. case DW_CFA_MIPS_advance_loc8: if (!ParseOperands("8", &ops)) return false; address_ += ops.offset * cie->code_alignment_factor; break; // Compute the CFA by adding an offset to a register. case DW_CFA_def_cfa: if (!ParseOperands("ro", &ops) || !DoDefCFA(ops.register_number, ops.offset)) return false; break; // Compute the CFA by adding an offset to a register. case DW_CFA_def_cfa_sf: if (!ParseOperands("rs", &ops) || !DoDefCFA(ops.register_number, ops.signed_offset * cie->data_alignment_factor)) return false; break; // Change the base register used to compute the CFA. case DW_CFA_def_cfa_register: { if (!ParseOperands("r", &ops)) return false; Rule *cfa_rule = rules_.CFARule(); if (!cfa_rule) { if (!DoDefCFA(ops.register_number, ops.offset)) { reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset()); return false; } } else { cfa_rule->SetBaseRegister(ops.register_number); if (!cfa_rule->Handle(handler_, address_, Handler::kCFARegister)) return false; } break; } // Change the offset used to compute the CFA. case DW_CFA_def_cfa_offset: if (!ParseOperands("o", &ops) || !DoDefCFAOffset(ops.offset)) return false; break; // Change the offset used to compute the CFA. case DW_CFA_def_cfa_offset_sf: if (!ParseOperands("s", &ops) || !DoDefCFAOffset(ops.signed_offset * cie->data_alignment_factor)) return false; break; // Specify an expression whose value is the CFA. case DW_CFA_def_cfa_expression: { if (!ParseOperands("e", &ops)) return false; Rule *rule = new ValExpressionRule(ops.expression); rules_.SetCFARule(rule); if (!rule->Handle(handler_, address_, Handler::kCFARegister)) return false; break; } // The register's value cannot be recovered. case DW_CFA_undefined: { if (!ParseOperands("r", &ops) || !DoRule(ops.register_number, new UndefinedRule())) return false; break; } // The register's value is unchanged from its value in the caller. case DW_CFA_same_value: { if (!ParseOperands("r", &ops) || !DoRule(ops.register_number, new SameValueRule())) return false; break; } // Find a register at an offset from the CFA. case DW_CFA_offset_extended: if (!ParseOperands("ro", &ops) || !DoOffset(ops.register_number, ops.offset * cie->data_alignment_factor)) return false; break; // The register is saved at an offset from the CFA. case DW_CFA_offset_extended_sf: if (!ParseOperands("rs", &ops) || !DoOffset(ops.register_number, ops.signed_offset * cie->data_alignment_factor)) return false; break; // The register is saved at an offset from the CFA. case DW_CFA_GNU_negative_offset_extended: if (!ParseOperands("ro", &ops) || !DoOffset(ops.register_number, -ops.offset * cie->data_alignment_factor)) return false; break; // The register's value is the sum of the CFA plus an offset. case DW_CFA_val_offset: if (!ParseOperands("ro", &ops) || !DoValOffset(ops.register_number, ops.offset * cie->data_alignment_factor)) return false; break; // The register's value is the sum of the CFA plus an offset. case DW_CFA_val_offset_sf: if (!ParseOperands("rs", &ops) || !DoValOffset(ops.register_number, ops.signed_offset * cie->data_alignment_factor)) return false; break; // The register has been saved in another register. case DW_CFA_register: { if (!ParseOperands("ro", &ops) || !DoRule(ops.register_number, new RegisterRule(ops.offset))) return false; break; } // An expression yields the address at which the register is saved. case DW_CFA_expression: { if (!ParseOperands("re", &ops) || !DoRule(ops.register_number, new ExpressionRule(ops.expression))) return false; break; } // An expression yields the caller's value for the register. case DW_CFA_val_expression: { if (!ParseOperands("re", &ops) || !DoRule(ops.register_number, new ValExpressionRule(ops.expression))) return false; break; } // Restore the rule established for a register by the CIE. case DW_CFA_restore_extended: if (!ParseOperands("r", &ops) || !DoRestore( ops.register_number)) return false; break; // Save the current set of rules on a stack. case DW_CFA_remember_state: saved_rules_.push(rules_); break; // Pop the current set of rules off the stack. case DW_CFA_restore_state: { if (saved_rules_.empty()) { reporter_->EmptyStateStack(entry_->offset, entry_->kind, CursorOffset()); return false; } const RuleMap &new_rules = saved_rules_.top(); if (rules_.CFARule() && !new_rules.CFARule()) { reporter_->ClearingCFARule(entry_->offset, entry_->kind, CursorOffset()); return false; } rules_.HandleTransitionTo(handler_, address_, new_rules); rules_ = new_rules; saved_rules_.pop(); break; } // No operation. (Padding instruction.) case DW_CFA_nop: break; // A SPARC register window save: Registers 8 through 15 (%o0-%o7) // are saved in registers 24 through 31 (%i0-%i7), and registers // 16 through 31 (%l0-%l7 and %i0-%i7) are saved at CFA offsets // (0-15 * the register size). The register numbers must be // hard-coded. A GNU extension, and not a pretty one. case DW_CFA_GNU_window_save: { // Save %o0-%o7 in %i0-%i7. for (int i = 8; i < 16; i++) if (!DoRule(i, new RegisterRule(i + 16))) return false; // Save %l0-%l7 and %i0-%i7 at the CFA. for (int i = 16; i < 32; i++) // Assume that the byte reader's address size is the same as // the architecture's register size. !@#%*^ hilarious. if (!DoRule(i, new OffsetRule(Handler::kCFARegister, (i - 16) * reader_->AddressSize()))) return false; break; } // I'm not sure what this is. GDB doesn't use it for unwinding. case DW_CFA_GNU_args_size: if (!ParseOperands("o", &ops)) return false; break; // An opcode we don't recognize. default: { reporter_->BadInstruction(entry_->offset, entry_->kind, CursorOffset()); return false; } } return true; } bool CallFrameInfo::State::DoDefCFA(unsigned base_register, long offset) { Rule *rule = new ValOffsetRule(base_register, offset); rules_.SetCFARule(rule); return rule->Handle(handler_, address_, Handler::kCFARegister); } bool CallFrameInfo::State::DoDefCFAOffset(long offset) { Rule *cfa_rule = rules_.CFARule(); if (!cfa_rule) { reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset()); return false; } cfa_rule->SetOffset(offset); return cfa_rule->Handle(handler_, address_, Handler::kCFARegister); } bool CallFrameInfo::State::DoRule(unsigned reg, Rule *rule) { rules_.SetRegisterRule(reg, rule); return rule->Handle(handler_, address_, reg); } bool CallFrameInfo::State::DoOffset(unsigned reg, long offset) { if (!rules_.CFARule()) { reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset()); return false; } return DoRule(reg, new OffsetRule(Handler::kCFARegister, offset)); } bool CallFrameInfo::State::DoValOffset(unsigned reg, long offset) { if (!rules_.CFARule()) { reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset()); return false; } return DoRule(reg, new ValOffsetRule(Handler::kCFARegister, offset)); } bool CallFrameInfo::State::DoRestore(unsigned reg) { // DW_CFA_restore and DW_CFA_restore_extended don't make sense in a CIE. if (entry_->kind == kCIE) { reporter_->RestoreInCIE(entry_->offset, CursorOffset()); return false; } Rule *rule = cie_rules_.RegisterRule(reg); if (!rule) { // This isn't really the right thing to do, but since CFI generally // only mentions callee-saves registers, and GCC's convention for // callee-saves registers is that they are unchanged, it's a good // approximation. rule = new SameValueRule(); } return DoRule(reg, rule); } bool CallFrameInfo::ReadEntryPrologue(const char *cursor, Entry *entry) { const char *buffer_end = buffer_ + buffer_length_; // Initialize enough of ENTRY for use in error reporting. entry->offset = cursor - buffer_; entry->start = cursor; entry->kind = kUnknown; entry->end = NULL; // Read the initial length. This sets reader_'s offset size. size_t length_size; uint64 length = reader_->ReadInitialLength(cursor, &length_size); if (length_size > size_t(buffer_end - cursor)) return ReportIncomplete(entry); cursor += length_size; // In a .eh_frame section, a length of zero marks the end of the series // of entries. if (length == 0 && eh_frame_) { entry->kind = kTerminator; entry->end = cursor; return true; } // Validate the length. if (length > size_t(buffer_end - cursor)) return ReportIncomplete(entry); // The length is the number of bytes after the initial length field; // we have that position handy at this point, so compute the end // now. (If we're parsing 64-bit-offset DWARF on a 32-bit machine, // and the length didn't fit in a size_t, we would have rejected it // above.) entry->end = cursor + length; // Parse the next field: either the offset of a CIE or a CIE id. size_t offset_size = reader_->OffsetSize(); if (offset_size > size_t(entry->end - cursor)) return ReportIncomplete(entry); entry->id = reader_->ReadOffset(cursor); // Don't advance cursor past id field yet; in .eh_frame data we need // the id's position to compute the section offset of an FDE's CIE. // Now we can decide what kind of entry this is. if (eh_frame_) { // In .eh_frame data, an ID of zero marks the entry as a CIE, and // anything else is an offset from the id field of the FDE to the start // of the CIE. if (entry->id == 0) { entry->kind = kCIE; } else { entry->kind = kFDE; // Turn the offset from the id into an offset from the buffer's start. entry->id = (cursor - buffer_) - entry->id; } } else { // In DWARF CFI data, an ID of ~0 (of the appropriate width, given the // offset size for the entry) marks the entry as a CIE, and anything // else is the offset of the CIE from the beginning of the section. if (offset_size == 4) entry->kind = (entry->id == 0xffffffff) ? kCIE : kFDE; else { assert(offset_size == 8); entry->kind = (entry->id == 0xffffffffffffffffULL) ? kCIE : kFDE; } } // Now advance cursor past the id. cursor += offset_size; // The fields specific to this kind of entry start here. entry->fields = cursor; entry->cie = NULL; return true; } bool CallFrameInfo::ReadCIEFields(CIE *cie) { const char *cursor = cie->fields; size_t len; assert(cie->kind == kCIE); // Prepare for early exit. cie->version = 0; cie->augmentation.clear(); cie->code_alignment_factor = 0; cie->data_alignment_factor = 0; cie->return_address_register = 0; cie->has_z_augmentation = false; cie->pointer_encoding = DW_EH_PE_absptr; cie->instructions = 0; // Parse the version number. if (cie->end - cursor < 1) return ReportIncomplete(cie); cie->version = reader_->ReadOneByte(cursor); cursor++; // If we don't recognize the version, we can't parse any more fields of the // CIE. For DWARF CFI, we handle versions 1 through 3 (there was never a // version 2 of CFI data). For .eh_frame, we handle versions 1 and 3 as well; // the difference between those versions seems to be the same as for // .debug_frame. if (cie->version < 1 || cie->version > 3) { reporter_->UnrecognizedVersion(cie->offset, cie->version); return false; } const char *augmentation_start = cursor; const void *augmentation_end = memchr(augmentation_start, '\0', cie->end - augmentation_start); if (! augmentation_end) return ReportIncomplete(cie); cursor = static_cast<const char *>(augmentation_end); cie->augmentation = string(augmentation_start, cursor - augmentation_start); // Skip the terminating '\0'. cursor++; // Is this CFI augmented? if (!cie->augmentation.empty()) { // Is it an augmentation we recognize? if (cie->augmentation[0] == DW_Z_augmentation_start) { // Linux C++ ABI 'z' augmentation, used for exception handling data. cie->has_z_augmentation = true; } else { // Not an augmentation we recognize. Augmentations can have arbitrary // effects on the form of rest of the content, so we have to give up. reporter_->UnrecognizedAugmentation(cie->offset, cie->augmentation); return false; } } // Parse the code alignment factor. cie->code_alignment_factor = reader_->ReadUnsignedLEB128(cursor, &len); if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie); cursor += len; // Parse the data alignment factor. cie->data_alignment_factor = reader_->ReadSignedLEB128(cursor, &len); if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie); cursor += len; // Parse the return address register. This is a ubyte in version 1, and // a ULEB128 in version 3. if (cie->version == 1) { if (cursor >= cie->end) return ReportIncomplete(cie); cie->return_address_register = uint8(*cursor++); } else { cie->return_address_register = reader_->ReadUnsignedLEB128(cursor, &len); if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie); cursor += len; } // If we have a 'z' augmentation string, find the augmentation data and // use the augmentation string to parse it. if (cie->has_z_augmentation) { uint64_t data_size = reader_->ReadUnsignedLEB128(cursor, &len); if (size_t(cie->end - cursor) < len + data_size) return ReportIncomplete(cie); cursor += len; const char *data = cursor; cursor += data_size; const char *data_end = cursor; cie->has_z_lsda = false; cie->has_z_personality = false; cie->has_z_signal_frame = false; // Walk the augmentation string, and extract values from the // augmentation data as the string directs. for (size_t i = 1; i < cie->augmentation.size(); i++) { switch (cie->augmentation[i]) { case DW_Z_has_LSDA: // The CIE's augmentation data holds the language-specific data // area pointer's encoding, and the FDE's augmentation data holds // the pointer itself. cie->has_z_lsda = true; // Fetch the LSDA encoding from the augmentation data. if (data >= data_end) return ReportIncomplete(cie); cie->lsda_encoding = DwarfPointerEncoding(*data++); if (!reader_->ValidEncoding(cie->lsda_encoding)) { reporter_->InvalidPointerEncoding(cie->offset, cie->lsda_encoding); return false; } // Don't check if the encoding is usable here --- we haven't // read the FDE's fields yet, so we're not prepared for // DW_EH_PE_funcrel, although that's a fine encoding for the // LSDA to use, since it appears in the FDE. break; case DW_Z_has_personality_routine: // The CIE's augmentation data holds the personality routine // pointer's encoding, followed by the pointer itself. cie->has_z_personality = true; // Fetch the personality routine pointer's encoding from the // augmentation data. if (data >= data_end) return ReportIncomplete(cie); cie->personality_encoding = DwarfPointerEncoding(*data++); if (!reader_->ValidEncoding(cie->personality_encoding)) { reporter_->InvalidPointerEncoding(cie->offset, cie->personality_encoding); return false; } if (!reader_->UsableEncoding(cie->personality_encoding)) { reporter_->UnusablePointerEncoding(cie->offset, cie->personality_encoding); return false; } // Fetch the personality routine's pointer itself from the data. cie->personality_address = reader_->ReadEncodedPointer(data, cie->personality_encoding, &len); if (len > size_t(data_end - data)) return ReportIncomplete(cie); data += len; break; case DW_Z_has_FDE_address_encoding: // The CIE's augmentation data holds the pointer encoding to use // for addresses in the FDE. if (data >= data_end) return ReportIncomplete(cie); cie->pointer_encoding = DwarfPointerEncoding(*data++); if (!reader_->ValidEncoding(cie->pointer_encoding)) { reporter_->InvalidPointerEncoding(cie->offset, cie->pointer_encoding); return false; } if (!reader_->UsableEncoding(cie->pointer_encoding)) { reporter_->UnusablePointerEncoding(cie->offset, cie->pointer_encoding); return false; } break; case DW_Z_is_signal_trampoline: // Frames using this CIE are signal delivery frames. cie->has_z_signal_frame = true; break; default: // An augmentation we don't recognize. reporter_->UnrecognizedAugmentation(cie->offset, cie->augmentation); return false; } } } // The CIE's instructions start here. cie->instructions = cursor; return true; } bool CallFrameInfo::ReadFDEFields(FDE *fde) { const char *cursor = fde->fields; size_t size; fde->address = reader_->ReadEncodedPointer(cursor, fde->cie->pointer_encoding, &size); if (size > size_t(fde->end - cursor)) return ReportIncomplete(fde); cursor += size; reader_->SetFunctionBase(fde->address); // For the length, we strip off the upper nybble of the encoding used for // the starting address. DwarfPointerEncoding length_encoding = DwarfPointerEncoding(fde->cie->pointer_encoding & 0x0f); fde->size = reader_->ReadEncodedPointer(cursor, length_encoding, &size); if (size > size_t(fde->end - cursor)) return ReportIncomplete(fde); cursor += size; // If the CIE has a 'z' augmentation string, then augmentation data // appears here. if (fde->cie->has_z_augmentation) { uint64_t data_size = reader_->ReadUnsignedLEB128(cursor, &size); if (size_t(fde->end - cursor) < size + data_size) return ReportIncomplete(fde); cursor += size; // In the abstract, we should walk the augmentation string, and extract // items from the FDE's augmentation data as we encounter augmentation // string characters that specify their presence: the ordering of items // in the augmentation string determines the arrangement of values in // the augmentation data. // // In practice, there's only ever one value in FDE augmentation data // that we support --- the LSDA pointer --- and we have to bail if we // see any unrecognized augmentation string characters. So if there is // anything here at all, we know what it is, and where it starts. if (fde->cie->has_z_lsda) { // Check whether the LSDA's pointer encoding is usable now: only once // we've parsed the FDE's starting address do we call reader_-> // SetFunctionBase, so that the DW_EH_PE_funcrel encoding becomes // usable. if (!reader_->UsableEncoding(fde->cie->lsda_encoding)) { reporter_->UnusablePointerEncoding(fde->cie->offset, fde->cie->lsda_encoding); return false; } fde->lsda_address = reader_->ReadEncodedPointer(cursor, fde->cie->lsda_encoding, &size); if (size > data_size) return ReportIncomplete(fde); // Ideally, we would also complain here if there were unconsumed // augmentation data. } cursor += data_size; } // The FDE's instructions start after those. fde->instructions = cursor; return true; } bool CallFrameInfo::Start() { const char *buffer_end = buffer_ + buffer_length_; const char *cursor; bool all_ok = true; const char *entry_end; bool ok; // Traverse all the entries in buffer_, skipping CIEs and offering // FDEs to the handler. for (cursor = buffer_; cursor < buffer_end; cursor = entry_end, all_ok = all_ok && ok) { FDE fde; // Make it easy to skip this entry with 'continue': assume that // things are not okay until we've checked all the data, and // prepare the address of the next entry. ok = false; // Read the entry's prologue. if (!ReadEntryPrologue(cursor, &fde)) { if (!fde.end) { // If we couldn't even figure out this entry's extent, then we // must stop processing entries altogether. all_ok = false; break; } entry_end = fde.end; continue; } // The next iteration picks up after this entry. entry_end = fde.end; // Did we see an .eh_frame terminating mark? if (fde.kind == kTerminator) { // If there appears to be more data left in the section after the // terminating mark, warn the user. But this is just a warning; // we leave all_ok true. if (fde.end < buffer_end) reporter_->EarlyEHTerminator(fde.offset); break; } // In this loop, we skip CIEs. We only parse them fully when we // parse an FDE that refers to them. This limits our memory // consumption (beyond the buffer itself) to that needed to // process the largest single entry. if (fde.kind != kFDE) { ok = true; continue; } // Validate the CIE pointer. if (fde.id > buffer_length_) { reporter_->CIEPointerOutOfRange(fde.offset, fde.id); continue; } CIE cie; // Parse this FDE's CIE header. if (!ReadEntryPrologue(buffer_ + fde.id, &cie)) continue; // This had better be an actual CIE. if (cie.kind != kCIE) { reporter_->BadCIEId(fde.offset, fde.id); continue; } if (!ReadCIEFields(&cie)) continue; // We now have the values that govern both the CIE and the FDE. cie.cie = &cie; fde.cie = &cie; // Parse the FDE's header. if (!ReadFDEFields(&fde)) continue; // Call Entry to ask the consumer if they're interested. if (!handler_->Entry(fde.offset, fde.address, fde.size, cie.version, cie.augmentation, cie.return_address_register)) { // The handler isn't interested in this entry. That's not an error. ok = true; continue; } if (cie.has_z_augmentation) { // Report the personality routine address, if we have one. if (cie.has_z_personality) { if (!handler_ ->PersonalityRoutine(cie.personality_address, IsIndirectEncoding(cie.personality_encoding))) continue; } // Report the language-specific data area address, if we have one. if (cie.has_z_lsda) { if (!handler_ ->LanguageSpecificDataArea(fde.lsda_address, IsIndirectEncoding(cie.lsda_encoding))) continue; } // If this is a signal-handling frame, report that. if (cie.has_z_signal_frame) { if (!handler_->SignalHandler()) continue; } } // Interpret the CIE's instructions, and then the FDE's instructions. State state(reader_, handler_, reporter_, fde.address); ok = state.InterpretCIE(cie) && state.InterpretFDE(fde); // Tell the ByteReader that the function start address from the // FDE header is no longer valid. reader_->ClearFunctionBase(); // Report the end of the entry. handler_->End(); } return all_ok; } const char *CallFrameInfo::KindName(EntryKind kind) { if (kind == CallFrameInfo::kUnknown) return "entry"; else if (kind == CallFrameInfo::kCIE) return "common information entry"; else if (kind == CallFrameInfo::kFDE) return "frame description entry"; else { assert (kind == CallFrameInfo::kTerminator); return ".eh_frame sequence terminator"; } } bool CallFrameInfo::ReportIncomplete(Entry *entry) { reporter_->Incomplete(entry->offset, entry->kind); return false; } void CallFrameInfo::Reporter::Incomplete(uint64 offset, CallFrameInfo::EntryKind kind) { fprintf(stderr, "%s: CFI %s at offset 0x%llx in '%s': entry ends early\n", filename_.c_str(), CallFrameInfo::KindName(kind), offset, section_.c_str()); } void CallFrameInfo::Reporter::EarlyEHTerminator(uint64 offset) { fprintf(stderr, "%s: CFI at offset 0x%llx in '%s': saw end-of-data marker" " before end of section contents\n", filename_.c_str(), offset, section_.c_str()); } void CallFrameInfo::Reporter::CIEPointerOutOfRange(uint64 offset, uint64 cie_offset) { fprintf(stderr, "%s: CFI frame description entry at offset 0x%llx in '%s':" " CIE pointer is out of range: 0x%llx\n", filename_.c_str(), offset, section_.c_str(), cie_offset); } void CallFrameInfo::Reporter::BadCIEId(uint64 offset, uint64 cie_offset) { fprintf(stderr, "%s: CFI frame description entry at offset 0x%llx in '%s':" " CIE pointer does not point to a CIE: 0x%llx\n", filename_.c_str(), offset, section_.c_str(), cie_offset); } void CallFrameInfo::Reporter::UnrecognizedVersion(uint64 offset, int version) { fprintf(stderr, "%s: CFI frame description entry at offset 0x%llx in '%s':" " CIE specifies unrecognized version: %d\n", filename_.c_str(), offset, section_.c_str(), version); } void CallFrameInfo::Reporter::UnrecognizedAugmentation(uint64 offset, const string &aug) { fprintf(stderr, "%s: CFI frame description entry at offset 0x%llx in '%s':" " CIE specifies unrecognized augmentation: '%s'\n", filename_.c_str(), offset, section_.c_str(), aug.c_str()); } void CallFrameInfo::Reporter::InvalidPointerEncoding(uint64 offset, uint8 encoding) { fprintf(stderr, "%s: CFI common information entry at offset 0x%llx in '%s':" " 'z' augmentation specifies invalid pointer encoding: 0x%02x\n", filename_.c_str(), offset, section_.c_str(), encoding); } void CallFrameInfo::Reporter::UnusablePointerEncoding(uint64 offset, uint8 encoding) { fprintf(stderr, "%s: CFI common information entry at offset 0x%llx in '%s':" " 'z' augmentation specifies a pointer encoding for which" " we have no base address: 0x%02x\n", filename_.c_str(), offset, section_.c_str(), encoding); } void CallFrameInfo::Reporter::RestoreInCIE(uint64 offset, uint64 insn_offset) { fprintf(stderr, "%s: CFI common information entry at offset 0x%llx in '%s':" " the DW_CFA_restore instruction at offset 0x%llx" " cannot be used in a common information entry\n", filename_.c_str(), offset, section_.c_str(), insn_offset); } void CallFrameInfo::Reporter::BadInstruction(uint64 offset, CallFrameInfo::EntryKind kind, uint64 insn_offset) { fprintf(stderr, "%s: CFI %s at offset 0x%llx in section '%s':" " the instruction at offset 0x%llx is unrecognized\n", filename_.c_str(), CallFrameInfo::KindName(kind), offset, section_.c_str(), insn_offset); } void CallFrameInfo::Reporter::NoCFARule(uint64 offset, CallFrameInfo::EntryKind kind, uint64 insn_offset) { fprintf(stderr, "%s: CFI %s at offset 0x%llx in section '%s':" " the instruction at offset 0x%llx assumes that a CFA rule has" " been set, but none has been set\n", filename_.c_str(), CallFrameInfo::KindName(kind), offset, section_.c_str(), insn_offset); } void CallFrameInfo::Reporter::EmptyStateStack(uint64 offset, CallFrameInfo::EntryKind kind, uint64 insn_offset) { fprintf(stderr, "%s: CFI %s at offset 0x%llx in section '%s':" " the DW_CFA_restore_state instruction at offset 0x%llx" " should pop a saved state from the stack, but the stack is empty\n", filename_.c_str(), CallFrameInfo::KindName(kind), offset, section_.c_str(), insn_offset); } void CallFrameInfo::Reporter::ClearingCFARule(uint64 offset, CallFrameInfo::EntryKind kind, uint64 insn_offset) { fprintf(stderr, "%s: CFI %s at offset 0x%llx in section '%s':" " the DW_CFA_restore_state instruction at offset 0x%llx" " would clear the CFA rule in effect\n", filename_.c_str(), CallFrameInfo::KindName(kind), offset, section_.c_str(), insn_offset); } } // namespace dwarf2reader