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diff --git a/3rdParty/Breakpad/src/common/dwarf/dwarf2reader.h b/3rdParty/Breakpad/src/common/dwarf/dwarf2reader.h new file mode 100644 index 0000000..ecf4eb2 --- /dev/null +++ b/3rdParty/Breakpad/src/common/dwarf/dwarf2reader.h @@ -0,0 +1,1051 @@ +// -*- mode: C++ -*- + +// 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> + +// This file contains definitions related to the DWARF2/3 reader and +// it's handler interfaces. +// The DWARF2/3 specification can be found at +// http://dwarf.freestandards.org and should be considered required +// reading if you wish to modify the implementation. +// Only a cursory attempt is made to explain terminology that is +// used here, as it is much better explained in the standard documents +#ifndef COMMON_DWARF_DWARF2READER_H__ +#define COMMON_DWARF_DWARF2READER_H__ + +#include <list> +#include <map> +#include <string> +#include <utility> +#include <vector> + +#include "common/dwarf/bytereader.h" +#include "common/dwarf/dwarf2enums.h" +#include "common/dwarf/types.h" +#include "common/using_std_string.h" + +namespace dwarf2reader { +struct LineStateMachine; +class Dwarf2Handler; +class LineInfoHandler; + +// This maps from a string naming a section to a pair containing a +// the data for the section, and the size of the section. +typedef std::map<string, std::pair<const char*, uint64> > SectionMap; +typedef std::list<std::pair<enum DwarfAttribute, enum DwarfForm> > + AttributeList; +typedef AttributeList::iterator AttributeIterator; +typedef AttributeList::const_iterator ConstAttributeIterator; + +struct LineInfoHeader { + uint64 total_length; + uint16 version; + uint64 prologue_length; + uint8 min_insn_length; // insn stands for instructin + bool default_is_stmt; // stmt stands for statement + int8 line_base; + uint8 line_range; + uint8 opcode_base; + // Use a pointer so that signalsafe_addr2line is able to use this structure + // without heap allocation problem. + std::vector<unsigned char> *std_opcode_lengths; +}; + +class LineInfo { + public: + + // Initializes a .debug_line reader. Buffer and buffer length point + // to the beginning and length of the line information to read. + // Reader is a ByteReader class that has the endianness set + // properly. + LineInfo(const char* buffer_, uint64 buffer_length, + ByteReader* reader, LineInfoHandler* handler); + + virtual ~LineInfo() { + if (header_.std_opcode_lengths) { + delete header_.std_opcode_lengths; + } + } + + // Start processing line info, and calling callbacks in the handler. + // Consumes the line number information for a single compilation unit. + // Returns the number of bytes processed. + uint64 Start(); + + // Process a single line info opcode at START using the state + // machine at LSM. Return true if we should define a line using the + // current state of the line state machine. Place the length of the + // opcode in LEN. + // If LSM_PASSES_PC is non-NULL, this function also checks if the lsm + // passes the address of PC. In other words, LSM_PASSES_PC will be + // set to true, if the following condition is met. + // + // lsm's old address < PC <= lsm's new address + static bool ProcessOneOpcode(ByteReader* reader, + LineInfoHandler* handler, + const struct LineInfoHeader &header, + const char* start, + struct LineStateMachine* lsm, + size_t* len, + uintptr pc, + bool *lsm_passes_pc); + + private: + // Reads the DWARF2/3 header for this line info. + void ReadHeader(); + + // Reads the DWARF2/3 line information + void ReadLines(); + + // The associated handler to call processing functions in + LineInfoHandler* handler_; + + // The associated ByteReader that handles endianness issues for us + ByteReader* reader_; + + // A DWARF2/3 line info header. This is not the same size as + // in the actual file, as the one in the file may have a 32 bit or + // 64 bit lengths + + struct LineInfoHeader header_; + + // buffer is the buffer for our line info, starting at exactly where + // the line info to read is. after_header is the place right after + // the end of the line information header. + const char* buffer_; + uint64 buffer_length_; + const char* after_header_; +}; + +// This class is the main interface between the line info reader and +// the client. The virtual functions inside this get called for +// interesting events that happen during line info reading. The +// default implementation does nothing + +class LineInfoHandler { + public: + LineInfoHandler() { } + + virtual ~LineInfoHandler() { } + + // Called when we define a directory. NAME is the directory name, + // DIR_NUM is the directory number + virtual void DefineDir(const string& name, uint32 dir_num) { } + + // Called when we define a filename. NAME is the filename, FILE_NUM + // is the file number which is -1 if the file index is the next + // index after the last numbered index (this happens when files are + // dynamically defined by the line program), DIR_NUM is the + // directory index for the directory name of this file, MOD_TIME is + // the modification time of the file, and LENGTH is the length of + // the file + virtual void DefineFile(const string& name, int32 file_num, + uint32 dir_num, uint64 mod_time, + uint64 length) { } + + // Called when the line info reader has a new line, address pair + // ready for us. ADDRESS is the address of the code, LENGTH is the + // length of its machine code in bytes, FILE_NUM is the file number + // containing the code, LINE_NUM is the line number in that file for + // the code, and COLUMN_NUM is the column number the code starts at, + // if we know it (0 otherwise). + virtual void AddLine(uint64 address, uint64 length, + uint32 file_num, uint32 line_num, uint32 column_num) { } +}; + +// The base of DWARF2/3 debug info is a DIE (Debugging Information +// Entry. +// DWARF groups DIE's into a tree and calls the root of this tree a +// "compilation unit". Most of the time, there is one compilation +// unit in the .debug_info section for each file that had debug info +// generated. +// Each DIE consists of + +// 1. a tag specifying a thing that is being described (ie +// DW_TAG_subprogram for functions, DW_TAG_variable for variables, etc +// 2. attributes (such as DW_AT_location for location in memory, +// DW_AT_name for name), and data for each attribute. +// 3. A flag saying whether the DIE has children or not + +// In order to gain some amount of compression, the format of +// each DIE (tag name, attributes and data forms for the attributes) +// are stored in a separate table called the "abbreviation table". +// This is done because a large number of DIEs have the exact same tag +// and list of attributes, but different data for those attributes. +// As a result, the .debug_info section is just a stream of data, and +// requires reading of the .debug_abbrev section to say what the data +// means. + +// As a warning to the user, it should be noted that the reason for +// using absolute offsets from the beginning of .debug_info is that +// DWARF2/3 supports referencing DIE's from other DIE's by their offset +// from either the current compilation unit start, *or* the beginning +// of the .debug_info section. This means it is possible to reference +// a DIE in one compilation unit from a DIE in another compilation +// unit. This style of reference is usually used to eliminate +// duplicated information that occurs across compilation +// units, such as base types, etc. GCC 3.4+ support this with +// -feliminate-dwarf2-dups. Other toolchains will sometimes do +// duplicate elimination in the linker. + +class CompilationUnit { + public: + + // Initialize a compilation unit. This requires a map of sections, + // the offset of this compilation unit in the .debug_info section, a + // ByteReader, and a Dwarf2Handler class to call callbacks in. + CompilationUnit(const SectionMap& sections, uint64 offset, + ByteReader* reader, Dwarf2Handler* handler); + virtual ~CompilationUnit() { + if (abbrevs_) delete abbrevs_; + } + + // Begin reading a Dwarf2 compilation unit, and calling the + // callbacks in the Dwarf2Handler + + // Return the full length of the compilation unit, including + // headers. This plus the starting offset passed to the constructor + // is the offset of the end of the compilation unit --- and the + // start of the next compilation unit, if there is one. + uint64 Start(); + + private: + + // This struct represents a single DWARF2/3 abbreviation + // The abbreviation tells how to read a DWARF2/3 DIE, and consist of a + // tag and a list of attributes, as well as the data form of each attribute. + struct Abbrev { + uint64 number; + enum DwarfTag tag; + bool has_children; + AttributeList attributes; + }; + + // A DWARF2/3 compilation unit header. This is not the same size as + // in the actual file, as the one in the file may have a 32 bit or + // 64 bit length. + struct CompilationUnitHeader { + uint64 length; + uint16 version; + uint64 abbrev_offset; + uint8 address_size; + } header_; + + // Reads the DWARF2/3 header for this compilation unit. + void ReadHeader(); + + // Reads the DWARF2/3 abbreviations for this compilation unit + void ReadAbbrevs(); + + // Processes a single DIE for this compilation unit and return a new + // pointer just past the end of it + const char* ProcessDIE(uint64 dieoffset, + const char* start, + const Abbrev& abbrev); + + // Processes a single attribute and return a new pointer just past the + // end of it + const char* ProcessAttribute(uint64 dieoffset, + const char* start, + enum DwarfAttribute attr, + enum DwarfForm form); + + // Processes all DIEs for this compilation unit + void ProcessDIEs(); + + // Skips the die with attributes specified in ABBREV starting at + // START, and return the new place to position the stream to. + const char* SkipDIE(const char* start, + const Abbrev& abbrev); + + // Skips the attribute starting at START, with FORM, and return the + // new place to position the stream to. + const char* SkipAttribute(const char* start, + enum DwarfForm form); + + // Offset from section start is the offset of this compilation unit + // from the beginning of the .debug_info section. + uint64 offset_from_section_start_; + + // buffer is the buffer for our CU, starting at .debug_info + offset + // passed in from constructor. + // after_header points to right after the compilation unit header. + const char* buffer_; + uint64 buffer_length_; + const char* after_header_; + + // The associated ByteReader that handles endianness issues for us + ByteReader* reader_; + + // The map of sections in our file to buffers containing their data + const SectionMap& sections_; + + // The associated handler to call processing functions in + Dwarf2Handler* handler_; + + // Set of DWARF2/3 abbreviations for this compilation unit. Indexed + // by abbreviation number, which means that abbrevs_[0] is not + // valid. + std::vector<Abbrev>* abbrevs_; + + // String section buffer and length, if we have a string section. + // This is here to avoid doing a section lookup for strings in + // ProcessAttribute, which is in the hot path for DWARF2 reading. + const char* string_buffer_; + uint64 string_buffer_length_; +}; + +// This class is the main interface between the reader and the +// client. The virtual functions inside this get called for +// interesting events that happen during DWARF2 reading. +// The default implementation skips everything. + +class Dwarf2Handler { + public: + Dwarf2Handler() { } + + virtual ~Dwarf2Handler() { } + + // Start to process a compilation unit at OFFSET from the beginning of the + // .debug_info section. Return false if you would like to skip this + // compilation unit. + virtual bool StartCompilationUnit(uint64 offset, uint8 address_size, + uint8 offset_size, uint64 cu_length, + uint8 dwarf_version) { return false; } + + // Start to process a DIE at OFFSET from the beginning of the .debug_info + // section. Return false if you would like to skip this DIE. + virtual bool StartDIE(uint64 offset, enum DwarfTag tag, + const AttributeList& attrs) { return false; } + + // Called when we have an attribute with unsigned data to give to our + // handler. The attribute is for the DIE at OFFSET from the beginning of the + // .debug_info section. Its name is ATTR, its form is FORM, and its value is + // DATA. + virtual void ProcessAttributeUnsigned(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + uint64 data) { } + + // Called when we have an attribute with signed data to give to our handler. + // The attribute is for the DIE at OFFSET from the beginning of the + // .debug_info section. Its name is ATTR, its form is FORM, and its value is + // DATA. + virtual void ProcessAttributeSigned(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + int64 data) { } + + // Called when we have an attribute whose value is a reference to + // another DIE. The attribute belongs to the DIE at OFFSET from the + // beginning of the .debug_info section. Its name is ATTR, its form + // is FORM, and the offset of the DIE being referred to from the + // beginning of the .debug_info section is DATA. + virtual void ProcessAttributeReference(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + uint64 data) { } + + // Called when we have an attribute with a buffer of data to give to our + // handler. The attribute is for the DIE at OFFSET from the beginning of the + // .debug_info section. Its name is ATTR, its form is FORM, DATA points to + // the buffer's contents, and its length in bytes is LENGTH. The buffer is + // owned by the caller, not the callee, and may not persist for very long. + // If you want the data to be available later, it needs to be copied. + virtual void ProcessAttributeBuffer(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + const char* data, + uint64 len) { } + + // Called when we have an attribute with string data to give to our handler. + // The attribute is for the DIE at OFFSET from the beginning of the + // .debug_info section. Its name is ATTR, its form is FORM, and its value is + // DATA. + virtual void ProcessAttributeString(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + const string& data) { } + + // Called when we have an attribute whose value is the 64-bit signature + // of a type unit in the .debug_types section. OFFSET is the offset of + // the DIE whose attribute we're reporting. ATTR and FORM are the + // attribute's name and form. SIGNATURE is the type unit's signature. + virtual void ProcessAttributeSignature(uint64 offset, + enum DwarfAttribute attr, + enum DwarfForm form, + uint64 signature) { } + + // Called when finished processing the DIE at OFFSET. + // Because DWARF2/3 specifies a tree of DIEs, you may get starts + // before ends of the previous DIE, as we process children before + // ending the parent. + virtual void EndDIE(uint64 offset) { } + +}; + +// This class is a reader for DWARF's Call Frame Information. CFI +// describes how to unwind stack frames --- even for functions that do +// not follow fixed conventions for saving registers, whose frame size +// varies as they execute, etc. +// +// CFI describes, at each machine instruction, how to compute the +// stack frame's base address, how to find the return address, and +// where to find the saved values of the caller's registers (if the +// callee has stashed them somewhere to free up the registers for its +// own use). +// +// For example, suppose we have a function whose machine code looks +// like this (imagine an assembly language that looks like C, for a +// machine with 32-bit registers, and a stack that grows towards lower +// addresses): +// +// func: ; entry point; return address at sp +// func+0: sp = sp - 16 ; allocate space for stack frame +// func+1: sp[12] = r0 ; save r0 at sp+12 +// ... ; other code, not frame-related +// func+10: sp -= 4; *sp = x ; push some x on the stack +// ... ; other code, not frame-related +// func+20: r0 = sp[16] ; restore saved r0 +// func+21: sp += 20 ; pop whole stack frame +// func+22: pc = *sp; sp += 4 ; pop return address and jump to it +// +// DWARF CFI is (a very compressed representation of) a table with a +// row for each machine instruction address and a column for each +// register showing how to restore it, if possible. +// +// A special column named "CFA", for "Canonical Frame Address", tells how +// to compute the base address of the frame; registers' entries may +// refer to the CFA in describing where the registers are saved. +// +// Another special column, named "RA", represents the return address. +// +// For example, here is a complete (uncompressed) table describing the +// function above: +// +// insn cfa r0 r1 ... ra +// ======================================= +// func+0: sp cfa[0] +// func+1: sp+16 cfa[0] +// func+2: sp+16 cfa[-4] cfa[0] +// func+11: sp+20 cfa[-4] cfa[0] +// func+21: sp+20 cfa[0] +// func+22: sp cfa[0] +// +// Some things to note here: +// +// - Each row describes the state of affairs *before* executing the +// instruction at the given address. Thus, the row for func+0 +// describes the state before we allocate the stack frame. In the +// next row, the formula for computing the CFA has changed, +// reflecting that allocation. +// +// - The other entries are written in terms of the CFA; this allows +// them to remain unchanged as the stack pointer gets bumped around. +// For example, the rule for recovering the return address (the "ra" +// column) remains unchanged throughout the function, even as the +// stack pointer takes on three different offsets from the return +// address. +// +// - Although we haven't shown it, most calling conventions designate +// "callee-saves" and "caller-saves" registers. The callee must +// preserve the values of callee-saves registers; if it uses them, +// it must save their original values somewhere, and restore them +// before it returns. In contrast, the callee is free to trash +// caller-saves registers; if the callee uses these, it will +// probably not bother to save them anywhere, and the CFI will +// probably mark their values as "unrecoverable". +// +// (However, since the caller cannot assume the callee was going to +// save them, caller-saves registers are probably dead in the caller +// anyway, so compilers usually don't generate CFA for caller-saves +// registers.) +// +// - Exactly where the CFA points is a matter of convention that +// depends on the architecture and ABI in use. In the example, the +// CFA is the value the stack pointer had upon entry to the +// function, pointing at the saved return address. But on the x86, +// the call frame information generated by GCC follows the +// convention that the CFA is the address *after* the saved return +// address. +// +// But by definition, the CFA remains constant throughout the +// lifetime of the frame. This makes it a useful value for other +// columns to refer to. It is also gives debuggers a useful handle +// for identifying a frame. +// +// If you look at the table above, you'll notice that a given entry is +// often the same as the one immediately above it: most instructions +// change only one or two aspects of the stack frame, if they affect +// it at all. The DWARF format takes advantage of this fact, and +// reduces the size of the data by mentioning only the addresses and +// columns at which changes take place. So for the above, DWARF CFI +// data would only actually mention the following: +// +// insn cfa r0 r1 ... ra +// ======================================= +// func+0: sp cfa[0] +// func+1: sp+16 +// func+2: cfa[-4] +// func+11: sp+20 +// func+21: r0 +// func+22: sp +// +// In fact, this is the way the parser reports CFI to the consumer: as +// a series of statements of the form, "At address X, column Y changed +// to Z," and related conventions for describing the initial state. +// +// Naturally, it would be impractical to have to scan the entire +// program's CFI, noting changes as we go, just to recover the +// unwinding rules in effect at one particular instruction. To avoid +// this, CFI data is grouped into "entries", each of which covers a +// specified range of addresses and begins with a complete statement +// of the rules for all recoverable registers at that starting +// address. Each entry typically covers a single function. +// +// Thus, to compute the contents of a given row of the table --- that +// is, rules for recovering the CFA, RA, and registers at a given +// instruction --- the consumer should find the entry that covers that +// instruction's address, start with the initial state supplied at the +// beginning of the entry, and work forward until it has processed all +// the changes up to and including those for the present instruction. +// +// There are seven kinds of rules that can appear in an entry of the +// table: +// +// - "undefined": The given register is not preserved by the callee; +// its value cannot be recovered. +// +// - "same value": This register has the same value it did in the callee. +// +// - offset(N): The register is saved at offset N from the CFA. +// +// - val_offset(N): The value the register had in the caller is the +// CFA plus offset N. (This is usually only useful for describing +// the stack pointer.) +// +// - register(R): The register's value was saved in another register R. +// +// - expression(E): Evaluating the DWARF expression E using the +// current frame's registers' values yields the address at which the +// register was saved. +// +// - val_expression(E): Evaluating the DWARF expression E using the +// current frame's registers' values yields the value the register +// had in the caller. + +class CallFrameInfo { + public: + // The different kinds of entries one finds in CFI. Used internally, + // and for error reporting. + enum EntryKind { kUnknown, kCIE, kFDE, kTerminator }; + + // The handler class to which the parser hands the parsed call frame + // information. Defined below. + class Handler; + + // A reporter class, which CallFrameInfo uses to report errors + // encountered while parsing call frame information. Defined below. + class Reporter; + + // Create a DWARF CFI parser. BUFFER points to the contents of the + // .debug_frame section to parse; BUFFER_LENGTH is its length in bytes. + // REPORTER is an error reporter the parser should use to report + // problems. READER is a ByteReader instance that has the endianness and + // address size set properly. Report the data we find to HANDLER. + // + // This class can also parse Linux C++ exception handling data, as found + // in '.eh_frame' sections. This data is a variant of DWARF CFI that is + // placed in loadable segments so that it is present in the program's + // address space, and is interpreted by the C++ runtime to search the + // call stack for a handler interested in the exception being thrown, + // actually pop the frames, and find cleanup code to run. + // + // There are two differences between the call frame information described + // in the DWARF standard and the exception handling data Linux places in + // the .eh_frame section: + // + // - Exception handling data uses uses a different format for call frame + // information entry headers. The distinguished CIE id, the way FDEs + // refer to their CIEs, and the way the end of the series of entries is + // determined are all slightly different. + // + // If the constructor's EH_FRAME argument is true, then the + // CallFrameInfo parses the entry headers as Linux C++ exception + // handling data. If EH_FRAME is false or omitted, the CallFrameInfo + // parses standard DWARF call frame information. + // + // - Linux C++ exception handling data uses CIE augmentation strings + // beginning with 'z' to specify the presence of additional data after + // the CIE and FDE headers and special encodings used for addresses in + // frame description entries. + // + // CallFrameInfo can handle 'z' augmentations in either DWARF CFI or + // exception handling data if you have supplied READER with the base + // addresses needed to interpret the pointer encodings that 'z' + // augmentations can specify. See the ByteReader interface for details + // about the base addresses. See the CallFrameInfo::Handler interface + // for details about the additional information one might find in + // 'z'-augmented data. + // + // Thus: + // + // - If you are parsing standard DWARF CFI, as found in a .debug_frame + // section, you should pass false for the EH_FRAME argument, or omit + // it, and you need not worry about providing READER with the + // additional base addresses. + // + // - If you want to parse Linux C++ exception handling data from a + // .eh_frame section, you should pass EH_FRAME as true, and call + // READER's Set*Base member functions before calling our Start method. + // + // - If you want to parse DWARF CFI that uses the 'z' augmentations + // (although I don't think any toolchain ever emits such data), you + // could pass false for EH_FRAME, but call READER's Set*Base members. + // + // The extensions the Linux C++ ABI makes to DWARF for exception + // handling are described here, rather poorly: + // http://refspecs.linux-foundation.org/LSB_4.0.0/LSB-Core-generic/LSB-Core-generic/dwarfext.html + // http://refspecs.linux-foundation.org/LSB_4.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html + // + // The mechanics of C++ exception handling, personality routines, + // and language-specific data areas are described here, rather nicely: + // http://www.codesourcery.com/public/cxx-abi/abi-eh.html + CallFrameInfo(const char *buffer, size_t buffer_length, + ByteReader *reader, Handler *handler, Reporter *reporter, + bool eh_frame = false) + : buffer_(buffer), buffer_length_(buffer_length), + reader_(reader), handler_(handler), reporter_(reporter), + eh_frame_(eh_frame) { } + + ~CallFrameInfo() { } + + // Parse the entries in BUFFER, reporting what we find to HANDLER. + // Return true if we reach the end of the section successfully, or + // false if we encounter an error. + bool Start(); + + // Return the textual name of KIND. For error reporting. + static const char *KindName(EntryKind kind); + + private: + + struct CIE; + + // A CFI entry, either an FDE or a CIE. + struct Entry { + // The starting offset of the entry in the section, for error + // reporting. + size_t offset; + + // The start of this entry in the buffer. + const char *start; + + // Which kind of entry this is. + // + // We want to be able to use this for error reporting even while we're + // in the midst of parsing. Error reporting code may assume that kind, + // offset, and start fields are valid, although kind may be kUnknown. + EntryKind kind; + + // The end of this entry's common prologue (initial length and id), and + // the start of this entry's kind-specific fields. + const char *fields; + + // The start of this entry's instructions. + const char *instructions; + + // The address past the entry's last byte in the buffer. (Note that + // since offset points to the entry's initial length field, and the + // length field is the number of bytes after that field, this is not + // simply buffer_ + offset + length.) + const char *end; + + // For both DWARF CFI and .eh_frame sections, this is the CIE id in a + // CIE, and the offset of the associated CIE in an FDE. + uint64 id; + + // The CIE that applies to this entry, if we've parsed it. If this is a + // CIE, then this field points to this structure. + CIE *cie; + }; + + // A common information entry (CIE). + struct CIE: public Entry { + uint8 version; // CFI data version number + string augmentation; // vendor format extension markers + uint64 code_alignment_factor; // scale for code address adjustments + int data_alignment_factor; // scale for stack pointer adjustments + unsigned return_address_register; // which register holds the return addr + + // True if this CIE includes Linux C++ ABI 'z' augmentation data. + bool has_z_augmentation; + + // Parsed 'z' augmentation data. These are meaningful only if + // has_z_augmentation is true. + bool has_z_lsda; // The 'z' augmentation included 'L'. + bool has_z_personality; // The 'z' augmentation included 'P'. + bool has_z_signal_frame; // The 'z' augmentation included 'S'. + + // If has_z_lsda is true, this is the encoding to be used for language- + // specific data area pointers in FDEs. + DwarfPointerEncoding lsda_encoding; + + // If has_z_personality is true, this is the encoding used for the + // personality routine pointer in the augmentation data. + DwarfPointerEncoding personality_encoding; + + // If has_z_personality is true, this is the address of the personality + // routine --- or, if personality_encoding & DW_EH_PE_indirect, the + // address where the personality routine's address is stored. + uint64 personality_address; + + // This is the encoding used for addresses in the FDE header and + // in DW_CFA_set_loc instructions. This is always valid, whether + // or not we saw a 'z' augmentation string; its default value is + // DW_EH_PE_absptr, which is what normal DWARF CFI uses. + DwarfPointerEncoding pointer_encoding; + }; + + // A frame description entry (FDE). + struct FDE: public Entry { + uint64 address; // start address of described code + uint64 size; // size of described code, in bytes + + // If cie->has_z_lsda is true, then this is the language-specific data + // area's address --- or its address's address, if cie->lsda_encoding + // has the DW_EH_PE_indirect bit set. + uint64 lsda_address; + }; + + // Internal use. + class Rule; + class UndefinedRule; + class SameValueRule; + class OffsetRule; + class ValOffsetRule; + class RegisterRule; + class ExpressionRule; + class ValExpressionRule; + class RuleMap; + class State; + + // Parse the initial length and id of a CFI entry, either a CIE, an FDE, + // or a .eh_frame end-of-data mark. CURSOR points to the beginning of the + // data to parse. On success, populate ENTRY as appropriate, and return + // true. On failure, report the problem, and return false. Even if we + // return false, set ENTRY->end to the first byte after the entry if we + // were able to figure that out, or NULL if we weren't. + bool ReadEntryPrologue(const char *cursor, Entry *entry); + + // Parse the fields of a CIE after the entry prologue, including any 'z' + // augmentation data. Assume that the 'Entry' fields of CIE are + // populated; use CIE->fields and CIE->end as the start and limit for + // parsing. On success, populate the rest of *CIE, and return true; on + // failure, report the problem and return false. + bool ReadCIEFields(CIE *cie); + + // Parse the fields of an FDE after the entry prologue, including any 'z' + // augmentation data. Assume that the 'Entry' fields of *FDE are + // initialized; use FDE->fields and FDE->end as the start and limit for + // parsing. Assume that FDE->cie is fully initialized. On success, + // populate the rest of *FDE, and return true; on failure, report the + // problem and return false. + bool ReadFDEFields(FDE *fde); + + // Report that ENTRY is incomplete, and return false. This is just a + // trivial wrapper for invoking reporter_->Incomplete; it provides a + // little brevity. + bool ReportIncomplete(Entry *entry); + + // Return true if ENCODING has the DW_EH_PE_indirect bit set. + static bool IsIndirectEncoding(DwarfPointerEncoding encoding) { + return encoding & DW_EH_PE_indirect; + } + + // The contents of the DWARF .debug_info section we're parsing. + const char *buffer_; + size_t buffer_length_; + + // 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_; + + // True if we are processing .eh_frame-format data. + bool eh_frame_; +}; + +// The handler class for CallFrameInfo. The a CFI parser calls the +// member functions of a handler object to report the data it finds. +class CallFrameInfo::Handler { + public: + // The pseudo-register number for the canonical frame address. + enum { kCFARegister = -1 }; + + Handler() { } + virtual ~Handler() { } + + // The parser has found CFI for the machine code at ADDRESS, + // extending for LENGTH bytes. OFFSET is the offset of the frame + // description entry in the section, for use in error messages. + // VERSION is the version number of the CFI format. AUGMENTATION is + // a string describing any producer-specific extensions present in + // the data. RETURN_ADDRESS is the number of the register that holds + // the address to which the function should return. + // + // Entry should return true to process this CFI, or false to skip to + // the next entry. + // + // The parser invokes Entry for each Frame Description Entry (FDE) + // it finds. The parser doesn't report Common Information Entries + // to the handler explicitly; instead, if the handler elects to + // process a given FDE, the parser reiterates the appropriate CIE's + // contents at the beginning of the FDE's rules. + virtual bool Entry(size_t offset, uint64 address, uint64 length, + uint8 version, const string &augmentation, + unsigned return_address) = 0; + + // When the Entry function returns true, the parser calls these + // handler functions repeatedly to describe the rules for recovering + // registers at each instruction in the given range of machine code. + // Immediately after a call to Entry, the handler should assume that + // the rule for each callee-saves register is "unchanged" --- that + // is, that the register still has the value it had in the caller. + // + // If a *Rule function returns true, we continue processing this entry's + // instructions. If a *Rule function returns false, we stop evaluating + // instructions, and skip to the next entry. Either way, we call End + // before going on to the next entry. + // + // In all of these functions, if the REG parameter is kCFARegister, then + // the rule describes how to find the canonical frame address. + // kCFARegister may be passed as a BASE_REGISTER argument, meaning that + // the canonical frame address should be used as the base address for the + // computation. All other REG values will be positive. + + // At ADDRESS, register REG's value is not recoverable. + virtual bool UndefinedRule(uint64 address, int reg) = 0; + + // At ADDRESS, register REG's value is the same as that it had in + // the caller. + virtual bool SameValueRule(uint64 address, int reg) = 0; + + // At ADDRESS, register REG has been saved at offset OFFSET from + // BASE_REGISTER. + virtual bool OffsetRule(uint64 address, int reg, + int base_register, long offset) = 0; + + // At ADDRESS, the caller's value of register REG is the current + // value of BASE_REGISTER plus OFFSET. (This rule doesn't provide an + // address at which the register's value is saved.) + virtual bool ValOffsetRule(uint64 address, int reg, + int base_register, long offset) = 0; + + // At ADDRESS, register REG has been saved in BASE_REGISTER. This differs + // from ValOffsetRule(ADDRESS, REG, BASE_REGISTER, 0), in that + // BASE_REGISTER is the "home" for REG's saved value: if you want to + // assign to a variable whose home is REG in the calling frame, you + // should put the value in BASE_REGISTER. + virtual bool RegisterRule(uint64 address, int reg, int base_register) = 0; + + // At ADDRESS, the DWARF expression EXPRESSION yields the address at + // which REG was saved. + virtual bool ExpressionRule(uint64 address, int reg, + const string &expression) = 0; + + // At ADDRESS, the DWARF expression EXPRESSION yields the caller's + // value for REG. (This rule doesn't provide an address at which the + // register's value is saved.) + virtual bool ValExpressionRule(uint64 address, int reg, + const string &expression) = 0; + + // Indicate that the rules for the address range reported by the + // last call to Entry are complete. End should return true if + // everything is okay, or false if an error has occurred and parsing + // should stop. + virtual bool End() = 0; + + // Handler functions for Linux C++ exception handling data. These are + // only called if the data includes 'z' augmentation strings. + + // The Linux C++ ABI uses an extension of the DWARF CFI format to + // walk the stack to propagate exceptions from the throw to the + // appropriate catch, and do the appropriate cleanups along the way. + // CFI entries used for exception handling have two additional data + // associated with them: + // + // - The "language-specific data area" describes which exception + // types the function has 'catch' clauses for, and indicates how + // to go about re-entering the function at the appropriate catch + // clause. If the exception is not caught, it describes the + // destructors that must run before the frame is popped. + // + // - The "personality routine" is responsible for interpreting the + // language-specific data area's contents, and deciding whether + // the exception should continue to propagate down the stack, + // perhaps after doing some cleanup for this frame, or whether the + // exception will be caught here. + // + // In principle, the language-specific data area is opaque to + // everybody but the personality routine. In practice, these values + // may be useful or interesting to readers with extra context, and + // we have to at least skip them anyway, so we might as well report + // them to the handler. + + // This entry's exception handling personality routine's address is + // ADDRESS. If INDIRECT is true, then ADDRESS is the address at + // which the routine's address is stored. The default definition for + // this handler function simply returns true, allowing parsing of + // the entry to continue. + virtual bool PersonalityRoutine(uint64 address, bool indirect) { + return true; + } + + // This entry's language-specific data area (LSDA) is located at + // ADDRESS. If INDIRECT is true, then ADDRESS is the address at + // which the area's address is stored. The default definition for + // this handler function simply returns true, allowing parsing of + // the entry to continue. + virtual bool LanguageSpecificDataArea(uint64 address, bool indirect) { + return true; + } + + // This entry describes a signal trampoline --- this frame is the + // caller of a signal handler. The default definition for this + // handler function simply returns true, allowing parsing of the + // entry to continue. + // + // The best description of the rationale for and meaning of signal + // trampoline CFI entries seems to be in the GCC bug database: + // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26208 + virtual bool SignalHandler() { return true; } +}; + +// The CallFrameInfo class makes calls on an instance of this class to +// report errors or warn about problems in the data it is parsing. The +// default definitions of these methods print a message to stderr, but +// you can make a derived class that overrides them. +class CallFrameInfo::Reporter { + public: + // Create an error reporter which attributes troubles to the section + // named SECTION in FILENAME. + // + // Normally SECTION would be .debug_frame, but the Mac puts CFI data + // in a Mach-O section named __debug_frame. If we support + // Linux-style exception handling data, we could be reading an + // .eh_frame section. + Reporter(const string &filename, + const string §ion = ".debug_frame") + : filename_(filename), section_(section) { } + virtual ~Reporter() { } + + // The CFI entry at OFFSET ends too early to be well-formed. KIND + // indicates what kind of entry it is; KIND can be kUnknown if we + // haven't parsed enough of the entry to tell yet. + virtual void Incomplete(uint64 offset, CallFrameInfo::EntryKind kind); + + // The .eh_frame data has a four-byte zero at OFFSET where the next + // entry's length would be; this is a terminator. However, the buffer + // length as given to the CallFrameInfo constructor says there should be + // more data. + virtual void EarlyEHTerminator(uint64 offset); + + // The FDE at OFFSET refers to the CIE at CIE_OFFSET, but the + // section is not that large. + virtual void CIEPointerOutOfRange(uint64 offset, uint64 cie_offset); + + // The FDE at OFFSET refers to the CIE at CIE_OFFSET, but the entry + // there is not a CIE. + virtual void BadCIEId(uint64 offset, uint64 cie_offset); + + // The FDE at OFFSET refers to a CIE with version number VERSION, + // which we don't recognize. We cannot parse DWARF CFI if it uses + // a version number we don't recognize. + virtual void UnrecognizedVersion(uint64 offset, int version); + + // The FDE at OFFSET refers to a CIE with augmentation AUGMENTATION, + // which we don't recognize. We cannot parse DWARF CFI if it uses + // augmentations we don't recognize. + virtual void UnrecognizedAugmentation(uint64 offset, + const string &augmentation); + + // The pointer encoding ENCODING, specified by the CIE at OFFSET, is not + // a valid encoding. + virtual void InvalidPointerEncoding(uint64 offset, uint8 encoding); + + // The pointer encoding ENCODING, specified by the CIE at OFFSET, depends + // on a base address which has not been supplied. + virtual void UnusablePointerEncoding(uint64 offset, uint8 encoding); + + // The CIE at OFFSET contains a DW_CFA_restore instruction at + // INSN_OFFSET, which may not appear in a CIE. + virtual void RestoreInCIE(uint64 offset, uint64 insn_offset); + + // The entry at OFFSET, of kind KIND, has an unrecognized + // instruction at INSN_OFFSET. + virtual void BadInstruction(uint64 offset, CallFrameInfo::EntryKind kind, + uint64 insn_offset); + + // The instruction at INSN_OFFSET in the entry at OFFSET, of kind + // KIND, establishes a rule that cites the CFA, but we have not + // established a CFA rule yet. + virtual void NoCFARule(uint64 offset, CallFrameInfo::EntryKind kind, + uint64 insn_offset); + + // The instruction at INSN_OFFSET in the entry at OFFSET, of kind + // KIND, is a DW_CFA_restore_state instruction, but the stack of + // saved states is empty. + virtual void EmptyStateStack(uint64 offset, CallFrameInfo::EntryKind kind, + uint64 insn_offset); + + // The DW_CFA_remember_state instruction at INSN_OFFSET in the entry + // at OFFSET, of kind KIND, would restore a state that has no CFA + // rule, whereas the current state does have a CFA rule. This is + // bogus input, which the CallFrameInfo::Handler interface doesn't + // (and shouldn't) have any way to report. + virtual void ClearingCFARule(uint64 offset, CallFrameInfo::EntryKind kind, + uint64 insn_offset); + + protected: + // The name of the file whose CFI we're reading. + string filename_; + + // The name of the CFI section in that file. + string section_; +}; + +} // namespace dwarf2reader + +#endif // UTIL_DEBUGINFO_DWARF2READER_H__ |