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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+
+// Copyright 2006, 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.
+
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// This file is derived from the following files in
+// toolkit/crashreporter/google-breakpad:
+// src/common/dwarf/types.h
+// src/common/dwarf/dwarf2enums.h
+// src/common/dwarf/bytereader.h
+// src/common/dwarf_cfi_to_module.h
+// src/common/dwarf/dwarf2reader.h
+
+#ifndef LulDwarfExt_h
+#define LulDwarfExt_h
+
+#include "LulDwarfSummariser.h"
+
+#include "mozilla/Assertions.h"
+
+#include <stdint.h>
+#include <string>
+
+typedef signed char int8;
+typedef short int16;
+typedef int int32;
+typedef long long int64;
+
+typedef unsigned char uint8;
+typedef unsigned short uint16;
+typedef unsigned int uint32;
+typedef unsigned long long uint64;
+
+#ifdef __PTRDIFF_TYPE__
+typedef __PTRDIFF_TYPE__ intptr;
+typedef unsigned __PTRDIFF_TYPE__ uintptr;
+#else
+# error "Can't find pointer-sized integral types."
+#endif
+
+namespace lul {
+
+class UniqueString;
+
+// This represents a read-only slice of the "image" (the temporarily mmaped-in
+// .so). It is used for representing byte ranges containing Dwarf expressions.
+// Note that equality (operator==) is on slice contents, not slice locations.
+struct ImageSlice {
+ const char* start_;
+ size_t length_;
+ ImageSlice() : start_(0), length_(0) {}
+ ImageSlice(const char* start, size_t length)
+ : start_(start), length_(length) {}
+ // Make one from a C string (for testing only). Note, the terminating zero
+ // is not included in the length.
+ explicit ImageSlice(const char* cstring)
+ : start_(cstring), length_(strlen(cstring)) {}
+ explicit ImageSlice(const std::string& str)
+ : start_(str.c_str()), length_(str.length()) {}
+ ImageSlice(const ImageSlice& other)
+ : start_(other.start_), length_(other.length_) {}
+ ImageSlice(ImageSlice& other)
+ : start_(other.start_), length_(other.length_) {}
+ bool operator==(const ImageSlice& other) const {
+ if (length_ != other.length_) {
+ return false;
+ }
+ // This relies on the fact that that memcmp returns zero whenever length_
+ // is zero.
+ return memcmp(start_, other.start_, length_) == 0;
+ }
+};
+
+// Exception handling frame description pointer formats, as described
+// by the Linux Standard Base Core Specification 4.0, section 11.5,
+// DWARF Extensions.
+enum DwarfPointerEncoding {
+ DW_EH_PE_absptr = 0x00,
+ DW_EH_PE_omit = 0xff,
+ DW_EH_PE_uleb128 = 0x01,
+ DW_EH_PE_udata2 = 0x02,
+ DW_EH_PE_udata4 = 0x03,
+ DW_EH_PE_udata8 = 0x04,
+ DW_EH_PE_sleb128 = 0x09,
+ DW_EH_PE_sdata2 = 0x0A,
+ DW_EH_PE_sdata4 = 0x0B,
+ DW_EH_PE_sdata8 = 0x0C,
+ DW_EH_PE_pcrel = 0x10,
+ DW_EH_PE_textrel = 0x20,
+ DW_EH_PE_datarel = 0x30,
+ DW_EH_PE_funcrel = 0x40,
+ DW_EH_PE_aligned = 0x50,
+
+ // The GNU toolchain sources define this enum value as well,
+ // simply to help classify the lower nybble values into signed and
+ // unsigned groups.
+ DW_EH_PE_signed = 0x08,
+
+ // This is not documented in LSB 4.0, but it is used in both the
+ // Linux and OS X toolchains. It can be added to any other
+ // encoding (except DW_EH_PE_aligned), and indicates that the
+ // encoded value represents the address at which the true address
+ // is stored, not the true address itself.
+ DW_EH_PE_indirect = 0x80
+};
+
+// We can't use the obvious name of LITTLE_ENDIAN and BIG_ENDIAN
+// because it conflicts with a macro
+enum Endianness { ENDIANNESS_BIG, ENDIANNESS_LITTLE };
+
+// A ByteReader knows how to read single- and multi-byte values of
+// various endiannesses, sizes, and encodings, as used in DWARF
+// debugging information and Linux C++ exception handling data.
+class ByteReader {
+ public:
+ // Construct a ByteReader capable of reading one-, two-, four-, and
+ // eight-byte values according to ENDIANNESS, absolute machine-sized
+ // addresses, DWARF-style "initial length" values, signed and
+ // unsigned LEB128 numbers, and Linux C++ exception handling data's
+ // encoded pointers.
+ explicit ByteReader(enum Endianness endianness);
+ virtual ~ByteReader();
+
+ // Read a single byte from BUFFER and return it as an unsigned 8 bit
+ // number.
+ uint8 ReadOneByte(const char* buffer) const;
+
+ // Read two bytes from BUFFER and return them as an unsigned 16 bit
+ // number, using this ByteReader's endianness.
+ uint16 ReadTwoBytes(const char* buffer) const;
+
+ // Read four bytes from BUFFER and return them as an unsigned 32 bit
+ // number, using this ByteReader's endianness. This function returns
+ // a uint64 so that it is compatible with ReadAddress and
+ // ReadOffset. The number it returns will never be outside the range
+ // of an unsigned 32 bit integer.
+ uint64 ReadFourBytes(const char* buffer) const;
+
+ // Read eight bytes from BUFFER and return them as an unsigned 64
+ // bit number, using this ByteReader's endianness.
+ uint64 ReadEightBytes(const char* buffer) const;
+
+ // Read an unsigned LEB128 (Little Endian Base 128) number from
+ // BUFFER and return it as an unsigned 64 bit integer. Set LEN to
+ // the number of bytes read.
+ //
+ // The unsigned LEB128 representation of an integer N is a variable
+ // number of bytes:
+ //
+ // - If N is between 0 and 0x7f, then its unsigned LEB128
+ // representation is a single byte whose value is N.
+ //
+ // - Otherwise, its unsigned LEB128 representation is (N & 0x7f) |
+ // 0x80, followed by the unsigned LEB128 representation of N /
+ // 128, rounded towards negative infinity.
+ //
+ // In other words, we break VALUE into groups of seven bits, put
+ // them in little-endian order, and then write them as eight-bit
+ // bytes with the high bit on all but the last.
+ uint64 ReadUnsignedLEB128(const char* buffer, size_t* len) const;
+
+ // Read a signed LEB128 number from BUFFER and return it as an
+ // signed 64 bit integer. Set LEN to the number of bytes read.
+ //
+ // The signed LEB128 representation of an integer N is a variable
+ // number of bytes:
+ //
+ // - If N is between -0x40 and 0x3f, then its signed LEB128
+ // representation is a single byte whose value is N in two's
+ // complement.
+ //
+ // - Otherwise, its signed LEB128 representation is (N & 0x7f) |
+ // 0x80, followed by the signed LEB128 representation of N / 128,
+ // rounded towards negative infinity.
+ //
+ // In other words, we break VALUE into groups of seven bits, put
+ // them in little-endian order, and then write them as eight-bit
+ // bytes with the high bit on all but the last.
+ int64 ReadSignedLEB128(const char* buffer, size_t* len) const;
+
+ // Indicate that addresses on this architecture are SIZE bytes long. SIZE
+ // must be either 4 or 8. (DWARF allows addresses to be any number of
+ // bytes in length from 1 to 255, but we only support 32- and 64-bit
+ // addresses at the moment.) You must call this before using the
+ // ReadAddress member function.
+ //
+ // For data in a .debug_info section, or something that .debug_info
+ // refers to like line number or macro data, the compilation unit
+ // header's address_size field indicates the address size to use. Call
+ // frame information doesn't indicate its address size (a shortcoming of
+ // the spec); you must supply the appropriate size based on the
+ // architecture of the target machine.
+ void SetAddressSize(uint8 size);
+
+ // Return the current address size, in bytes. This is either 4,
+ // indicating 32-bit addresses, or 8, indicating 64-bit addresses.
+ uint8 AddressSize() const { return address_size_; }
+
+ // Read an address from BUFFER and return it as an unsigned 64 bit
+ // integer, respecting this ByteReader's endianness and address size. You
+ // must call SetAddressSize before calling this function.
+ uint64 ReadAddress(const char* buffer) const;
+
+ // DWARF actually defines two slightly different formats: 32-bit DWARF
+ // and 64-bit DWARF. This is *not* related to the size of registers or
+ // addresses on the target machine; it refers only to the size of section
+ // offsets and data lengths appearing in the DWARF data. One only needs
+ // 64-bit DWARF when the debugging data itself is larger than 4GiB.
+ // 32-bit DWARF can handle x86_64 or PPC64 code just fine, unless the
+ // debugging data itself is very large.
+ //
+ // DWARF information identifies itself as 32-bit or 64-bit DWARF: each
+ // compilation unit and call frame information entry begins with an
+ // "initial length" field, which, in addition to giving the length of the
+ // data, also indicates the size of section offsets and lengths appearing
+ // in that data. The ReadInitialLength member function, below, reads an
+ // initial length and sets the ByteReader's offset size as a side effect.
+ // Thus, in the normal process of reading DWARF data, the appropriate
+ // offset size is set automatically. So, you should only need to call
+ // SetOffsetSize if you are using the same ByteReader to jump from the
+ // midst of one block of DWARF data into another.
+
+ // Read a DWARF "initial length" field from START, and return it as
+ // an unsigned 64 bit integer, respecting this ByteReader's
+ // endianness. Set *LEN to the length of the initial length in
+ // bytes, either four or twelve. As a side effect, set this
+ // ByteReader's offset size to either 4 (if we see a 32-bit DWARF
+ // initial length) or 8 (if we see a 64-bit DWARF initial length).
+ //
+ // A DWARF initial length is either:
+ //
+ // - a byte count stored as an unsigned 32-bit value less than
+ // 0xffffff00, indicating that the data whose length is being
+ // measured uses the 32-bit DWARF format, or
+ //
+ // - The 32-bit value 0xffffffff, followed by a 64-bit byte count,
+ // indicating that the data whose length is being measured uses
+ // the 64-bit DWARF format.
+ uint64 ReadInitialLength(const char* start, size_t* len);
+
+ // Read an offset from BUFFER and return it as an unsigned 64 bit
+ // integer, respecting the ByteReader's endianness. In 32-bit DWARF, the
+ // offset is 4 bytes long; in 64-bit DWARF, the offset is eight bytes
+ // long. You must call ReadInitialLength or SetOffsetSize before calling
+ // this function; see the comments above for details.
+ uint64 ReadOffset(const char* buffer) const;
+
+ // Return the current offset size, in bytes.
+ // A return value of 4 indicates that we are reading 32-bit DWARF.
+ // A return value of 8 indicates that we are reading 64-bit DWARF.
+ uint8 OffsetSize() const { return offset_size_; }
+
+ // Indicate that section offsets and lengths are SIZE bytes long. SIZE
+ // must be either 4 (meaning 32-bit DWARF) or 8 (meaning 64-bit DWARF).
+ // Usually, you should not call this function yourself; instead, let a
+ // call to ReadInitialLength establish the data's offset size
+ // automatically.
+ void SetOffsetSize(uint8 size);
+
+ // The Linux C++ ABI uses a variant of DWARF call frame information
+ // for exception handling. This data is included in the program's
+ // address space as the ".eh_frame" section, and intepreted at
+ // runtime to walk the stack, find exception handlers, and run
+ // cleanup code. The format is mostly the same as DWARF CFI, with
+ // some adjustments made to provide the additional
+ // exception-handling data, and to make the data easier to work with
+ // in memory --- for example, to allow it to be placed in read-only
+ // memory even when describing position-independent code.
+ //
+ // In particular, exception handling data can select a number of
+ // different encodings for pointers that appear in the data, as
+ // described by the DwarfPointerEncoding enum. There are actually
+ // four axes(!) to the encoding:
+ //
+ // - The pointer size: pointers can be 2, 4, or 8 bytes long, or use
+ // the DWARF LEB128 encoding.
+ //
+ // - The pointer's signedness: pointers can be signed or unsigned.
+ //
+ // - The pointer's base address: the data stored in the exception
+ // handling data can be the actual address (that is, an absolute
+ // pointer), or relative to one of a number of different base
+ // addreses --- including that of the encoded pointer itself, for
+ // a form of "pc-relative" addressing.
+ //
+ // - The pointer may be indirect: it may be the address where the
+ // true pointer is stored. (This is used to refer to things via
+ // global offset table entries, program linkage table entries, or
+ // other tricks used in position-independent code.)
+ //
+ // There are also two options that fall outside that matrix
+ // altogether: the pointer may be omitted, or it may have padding to
+ // align it on an appropriate address boundary. (That last option
+ // may seem like it should be just another axis, but it is not.)
+
+ // Indicate that the exception handling data is loaded starting at
+ // SECTION_BASE, and that the start of its buffer in our own memory
+ // is BUFFER_BASE. This allows us to find the address that a given
+ // byte in our buffer would have when loaded into the program the
+ // data describes. We need this to resolve DW_EH_PE_pcrel pointers.
+ void SetCFIDataBase(uint64 section_base, const char* buffer_base);
+
+ // Indicate that the base address of the program's ".text" section
+ // is TEXT_BASE. We need this to resolve DW_EH_PE_textrel pointers.
+ void SetTextBase(uint64 text_base);
+
+ // Indicate that the base address for DW_EH_PE_datarel pointers is
+ // DATA_BASE. The proper value depends on the ABI; it is usually the
+ // address of the global offset table, held in a designated register in
+ // position-independent code. You will need to look at the startup code
+ // for the target system to be sure. I tried; my eyes bled.
+ void SetDataBase(uint64 data_base);
+
+ // Indicate that the base address for the FDE we are processing is
+ // FUNCTION_BASE. This is the start address of DW_EH_PE_funcrel
+ // pointers. (This encoding does not seem to be used by the GNU
+ // toolchain.)
+ void SetFunctionBase(uint64 function_base);
+
+ // Indicate that we are no longer processing any FDE, so any use of
+ // a DW_EH_PE_funcrel encoding is an error.
+ void ClearFunctionBase();
+
+ // Return true if ENCODING is a valid pointer encoding.
+ bool ValidEncoding(DwarfPointerEncoding encoding) const;
+
+ // Return true if we have all the information we need to read a
+ // pointer that uses ENCODING. This checks that the appropriate
+ // SetFooBase function for ENCODING has been called.
+ bool UsableEncoding(DwarfPointerEncoding encoding) const;
+
+ // Read an encoded pointer from BUFFER using ENCODING; return the
+ // absolute address it represents, and set *LEN to the pointer's
+ // length in bytes, including any padding for aligned pointers.
+ //
+ // This function calls 'abort' if ENCODING is invalid or refers to a
+ // base address this reader hasn't been given, so you should check
+ // with ValidEncoding and UsableEncoding first if you would rather
+ // die in a more helpful way.
+ uint64 ReadEncodedPointer(const char* buffer, DwarfPointerEncoding encoding,
+ size_t* len) const;
+
+ private:
+ // Function pointer type for our address and offset readers.
+ typedef uint64 (ByteReader::*AddressReader)(const char*) const;
+
+ // Read an offset from BUFFER and return it as an unsigned 64 bit
+ // integer. DWARF2/3 define offsets as either 4 or 8 bytes,
+ // generally depending on the amount of DWARF2/3 info present.
+ // This function pointer gets set by SetOffsetSize.
+ AddressReader offset_reader_;
+
+ // Read an address from BUFFER and return it as an unsigned 64 bit
+ // integer. DWARF2/3 allow addresses to be any size from 0-255
+ // bytes currently. Internally we support 4 and 8 byte addresses,
+ // and will CHECK on anything else.
+ // This function pointer gets set by SetAddressSize.
+ AddressReader address_reader_;
+
+ Endianness endian_;
+ uint8 address_size_;
+ uint8 offset_size_;
+
+ // Base addresses for Linux C++ exception handling data's encoded pointers.
+ bool have_section_base_, have_text_base_, have_data_base_;
+ bool have_function_base_;
+ uint64 section_base_;
+ uint64 text_base_, data_base_, function_base_;
+ const char* buffer_base_;
+};
+
+inline uint8 ByteReader::ReadOneByte(const char* buffer) const {
+ return buffer[0];
+}
+
+inline uint16 ByteReader::ReadTwoBytes(const char* signed_buffer) const {
+ const unsigned char* buffer =
+ reinterpret_cast<const unsigned char*>(signed_buffer);
+ const uint16 buffer0 = buffer[0];
+ const uint16 buffer1 = buffer[1];
+ if (endian_ == ENDIANNESS_LITTLE) {
+ return buffer0 | buffer1 << 8;
+ } else {
+ return buffer1 | buffer0 << 8;
+ }
+}
+
+inline uint64 ByteReader::ReadFourBytes(const char* signed_buffer) const {
+ const unsigned char* buffer =
+ reinterpret_cast<const unsigned char*>(signed_buffer);
+ const uint32 buffer0 = buffer[0];
+ const uint32 buffer1 = buffer[1];
+ const uint32 buffer2 = buffer[2];
+ const uint32 buffer3 = buffer[3];
+ if (endian_ == ENDIANNESS_LITTLE) {
+ return buffer0 | buffer1 << 8 | buffer2 << 16 | buffer3 << 24;
+ } else {
+ return buffer3 | buffer2 << 8 | buffer1 << 16 | buffer0 << 24;
+ }
+}
+
+inline uint64 ByteReader::ReadEightBytes(const char* signed_buffer) const {
+ const unsigned char* buffer =
+ reinterpret_cast<const unsigned char*>(signed_buffer);
+ const uint64 buffer0 = buffer[0];
+ const uint64 buffer1 = buffer[1];
+ const uint64 buffer2 = buffer[2];
+ const uint64 buffer3 = buffer[3];
+ const uint64 buffer4 = buffer[4];
+ const uint64 buffer5 = buffer[5];
+ const uint64 buffer6 = buffer[6];
+ const uint64 buffer7 = buffer[7];
+ if (endian_ == ENDIANNESS_LITTLE) {
+ return buffer0 | buffer1 << 8 | buffer2 << 16 | buffer3 << 24 |
+ buffer4 << 32 | buffer5 << 40 | buffer6 << 48 | buffer7 << 56;
+ } else {
+ return buffer7 | buffer6 << 8 | buffer5 << 16 | buffer4 << 24 |
+ buffer3 << 32 | buffer2 << 40 | buffer1 << 48 | buffer0 << 56;
+ }
+}
+
+// Read an unsigned LEB128 number. Each byte contains 7 bits of
+// information, plus one bit saying whether the number continues or
+// not.
+
+inline uint64 ByteReader::ReadUnsignedLEB128(const char* buffer,
+ size_t* len) const {
+ uint64 result = 0;
+ size_t num_read = 0;
+ unsigned int shift = 0;
+ unsigned char byte;
+
+ do {
+ byte = *buffer++;
+ num_read++;
+
+ result |= (static_cast<uint64>(byte & 0x7f)) << shift;
+
+ shift += 7;
+
+ } while (byte & 0x80);
+
+ *len = num_read;
+
+ return result;
+}
+
+// Read a signed LEB128 number. These are like regular LEB128
+// numbers, except the last byte may have a sign bit set.
+
+inline int64 ByteReader::ReadSignedLEB128(const char* buffer,
+ size_t* len) const {
+ int64 result = 0;
+ unsigned int shift = 0;
+ size_t num_read = 0;
+ unsigned char byte;
+
+ do {
+ byte = *buffer++;
+ num_read++;
+ result |= (static_cast<uint64>(byte & 0x7f) << shift);
+ shift += 7;
+ } while (byte & 0x80);
+
+ if ((shift < 8 * sizeof(result)) && (byte & 0x40))
+ result |= -((static_cast<int64>(1)) << shift);
+ *len = num_read;
+ return result;
+}
+
+inline uint64 ByteReader::ReadOffset(const char* buffer) const {
+ MOZ_ASSERT(this->offset_reader_);
+ return (this->*offset_reader_)(buffer);
+}
+
+inline uint64 ByteReader::ReadAddress(const char* buffer) const {
+ MOZ_ASSERT(this->address_reader_);
+ return (this->*address_reader_)(buffer);
+}
+
+inline void ByteReader::SetCFIDataBase(uint64 section_base,
+ const char* buffer_base) {
+ section_base_ = section_base;
+ buffer_base_ = buffer_base;
+ have_section_base_ = true;
+}
+
+inline void ByteReader::SetTextBase(uint64 text_base) {
+ text_base_ = text_base;
+ have_text_base_ = true;
+}
+
+inline void ByteReader::SetDataBase(uint64 data_base) {
+ data_base_ = data_base;
+ have_data_base_ = true;
+}
+
+inline void ByteReader::SetFunctionBase(uint64 function_base) {
+ function_base_ = function_base;
+ have_function_base_ = true;
+}
+
+inline void ByteReader::ClearFunctionBase() { have_function_base_ = false; }
+
+// (derived from)
+// dwarf_cfi_to_module.h: Define the DwarfCFIToModule class, which
+// accepts parsed DWARF call frame info and adds it to a Summariser object.
+
+// 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
+ std::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 RuleMapLowLevel;
+ 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 = DW_REG_CFA };
+
+ 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 std::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 ImageSlice& 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 ImageSlice& 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.
+// These messages are sent to the message sink |aLog| provided to the
+// constructor.
+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(void (*aLog)(const char*), const std::string& filename,
+ const std::string& section = ".debug_frame")
+ : log_(aLog), 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 std::string& augmentation);
+
+ // The FDE at OFFSET contains an invalid or otherwise unusable Dwarf4
+ // specific field (currently, only "address_size" or "segment_size").
+ // Parsing DWARF CFI with unexpected values here seems dubious at best,
+ // so we stop. WHAT gives a little more information about what is wrong.
+ virtual void InvalidDwarf4Artefact(uint64 offset, const char* what);
+
+ // 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);
+
+ private:
+ // A logging sink function, as supplied by LUL's user.
+ void (*log_)(const char*);
+
+ protected:
+ // The name of the file whose CFI we're reading.
+ std::string filename_;
+
+ // The name of the CFI section in that file.
+ std::string section_;
+};
+
+using lul::CallFrameInfo;
+using lul::Summariser;
+
+// A class that accepts parsed call frame information from the DWARF
+// CFI parser and populates a google_breakpad::Module object with the
+// contents.
+class DwarfCFIToModule : public CallFrameInfo::Handler {
+ public:
+ // DwarfCFIToModule uses an instance of this class to report errors
+ // detected while converting DWARF CFI to Breakpad STACK CFI records.
+ class Reporter {
+ public:
+ // Create a reporter that writes messages to the message sink
+ // |aLog|. FILE is the name of the file we're processing, and
+ // SECTION is the name of the section within that file that we're
+ // looking at (.debug_frame, .eh_frame, etc.).
+ Reporter(void (*aLog)(const char*), const std::string& file,
+ const std::string& section)
+ : log_(aLog), file_(file), section_(section) {}
+ virtual ~Reporter() {}
+
+ // The DWARF CFI entry at OFFSET says that REG is undefined, but the
+ // Breakpad symbol file format cannot express this.
+ virtual void UndefinedNotSupported(size_t offset, const UniqueString* reg);
+
+ // The DWARF CFI entry at OFFSET says that REG uses a DWARF
+ // expression to find its value, but parseDwarfExpr could not
+ // convert it to a sequence of PfxInstrs.
+ virtual void ExpressionCouldNotBeSummarised(size_t offset,
+ const UniqueString* reg);
+
+ private:
+ // A logging sink function, as supplied by LUL's user.
+ void (*log_)(const char*);
+
+ protected:
+ std::string file_, section_;
+ };
+
+ // Register name tables. If TABLE is a vector returned by one of these
+ // functions, then TABLE[R] is the name of the register numbered R in
+ // DWARF call frame information.
+ class RegisterNames {
+ public:
+ // Intel's "x86" or IA-32.
+ static unsigned int I386();
+
+ // AMD x86_64, AMD64, Intel EM64T, or Intel 64
+ static unsigned int X86_64();
+
+ // ARM.
+ static unsigned int ARM();
+
+ // AARCH64.
+ static unsigned int ARM64();
+
+ // MIPS.
+ static unsigned int MIPS();
+ };
+
+ // Create a handler for the dwarf2reader::CallFrameInfo parser that
+ // records the stack unwinding information it receives in SUMM.
+ //
+ // Use REGISTER_NAMES[I] as the name of register number I; *this
+ // keeps a reference to the vector, so the vector should remain
+ // alive for as long as the DwarfCFIToModule does.
+ //
+ // Use REPORTER for reporting problems encountered in the conversion
+ // process.
+ DwarfCFIToModule(const unsigned int num_dw_regs, Reporter* reporter,
+ ByteReader* reader,
+ /*MOD*/ UniqueStringUniverse* usu,
+ /*OUT*/ Summariser* summ)
+ : summ_(summ),
+ usu_(usu),
+ num_dw_regs_(num_dw_regs),
+ reporter_(reporter),
+ reader_(reader),
+ return_address_(-1) {}
+ virtual ~DwarfCFIToModule() {}
+
+ virtual bool Entry(size_t offset, uint64 address, uint64 length,
+ uint8 version, const std::string& augmentation,
+ unsigned return_address) override;
+ virtual bool UndefinedRule(uint64 address, int reg) override;
+ virtual bool SameValueRule(uint64 address, int reg) override;
+ virtual bool OffsetRule(uint64 address, int reg, int base_register,
+ long offset) override;
+ virtual bool ValOffsetRule(uint64 address, int reg, int base_register,
+ long offset) override;
+ virtual bool RegisterRule(uint64 address, int reg,
+ int base_register) override;
+ virtual bool ExpressionRule(uint64 address, int reg,
+ const ImageSlice& expression) override;
+ virtual bool ValExpressionRule(uint64 address, int reg,
+ const ImageSlice& expression) override;
+ virtual bool End() override;
+
+ private:
+ // Return the name to use for register I.
+ const UniqueString* RegisterName(int i);
+
+ // The Summariser to which we should give entries
+ Summariser* summ_;
+
+ // Universe for creating UniqueStrings in, should that be necessary.
+ UniqueStringUniverse* usu_;
+
+ // The number of Dwarf-defined register names for this architecture.
+ const unsigned int num_dw_regs_;
+
+ // The reporter to use to report problems.
+ Reporter* reporter_;
+
+ // The ByteReader to use for parsing Dwarf expressions.
+ ByteReader* reader_;
+
+ // The section offset of the current frame description entry, for
+ // use in error messages.
+ size_t entry_offset_;
+
+ // The return address column for that entry.
+ unsigned return_address_;
+};
+
+// Convert the Dwarf expression in |expr| into PfxInstrs stored in the
+// SecMap referred to by |summ|, and return the index of the starting
+// PfxInstr added, which must be >= 0. In case of failure return -1.
+int32_t parseDwarfExpr(Summariser* summ, const ByteReader* reader,
+ ImageSlice expr, bool debug, bool pushCfaAtStart,
+ bool derefAtEnd);
+
+} // namespace lul
+
+#endif // LulDwarfExt_h