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breakpad/src/common/dwarf/dwarf2reader.cc
Sterling Augustine 2b936b06c1 Refactor rangelist handling to prepare for dwarf5 .debug_rngslist 
Dwarf5 introduces a new .debug_rngslist section, to take the place
of the Dwarf4 .debug_ranges. However, the dwarf version is CU-based,
and not file-based, so there can be both sections, and which section
the CU needs isn't known until the dwarf parser encounters either
DW_AT_ranges (dwarf 4 and lower) or DW_AT_rnglists_base (dwarf 5).

This change refactors the code around range lists and range list
readers to defer the decision of what section to parse until
the relevant attribute is found. It moves the range list section
reader from the range-list handler itself (which doesn't know which
section it will use) to the CU context, and then lets the handler
know when it encounters DW_AT_ranges.

I will add a reader for the new dwarf5 section, along with the code to
interpret the new section, and its forms and such in a subsequent patch.

Change-Id: Ie92e4c9daa3f0acb98d7ef74f6b9c2065db849b1
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/2433684
Reviewed-by: Mark Mentovai <mark@chromium.org>
2020-09-28 17:56:12 +00:00

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// Copyright (c) 2010 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// CFI reader author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
// Implementation of dwarf2reader::LineInfo, dwarf2reader::CompilationUnit,
// and dwarf2reader::CallFrameInfo. See dwarf2reader.h for details.
#include "common/dwarf/dwarf2reader.h"
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <map>
#include <memory>
#include <stack>
#include <string>
#include <utility>
#include <sys/stat.h>
#include "common/dwarf/bytereader-inl.h"
#include "common/dwarf/bytereader.h"
#include "common/dwarf/line_state_machine.h"
#include "common/using_std_string.h"
#include "google_breakpad/common/breakpad_types.h"
namespace dwarf2reader {
const SectionMap::const_iterator GetSectionByName(const SectionMap&
sections, const char *name) {
assert(name[0] == '.');
auto iter = sections.find(name);
if (iter != sections.end())
return iter;
std::string macho_name("__");
macho_name += name + 1;
iter = sections.find(macho_name);
return iter;
}
CompilationUnit::CompilationUnit(const string& path,
const SectionMap& sections, uint64_t offset,
ByteReader* reader, Dwarf2Handler* handler)
: path_(path), offset_from_section_start_(offset), reader_(reader),
sections_(sections), handler_(handler), abbrevs_(),
string_buffer_(NULL), string_buffer_length_(0),
line_string_buffer_(NULL), line_string_buffer_length_(0),
str_offsets_buffer_(NULL), str_offsets_buffer_length_(0),
addr_buffer_(NULL), addr_buffer_length_(0),
is_split_dwarf_(false), dwo_id_(0), dwo_name_(),
skeleton_dwo_id_(0), ranges_base_(0), addr_base_(0),
have_checked_for_dwp_(false), dwp_path_(),
dwp_byte_reader_(), dwp_reader_() {}
// Initialize a compilation unit from a .dwo or .dwp file.
// In this case, we need the .debug_addr section from the
// executable file that contains the corresponding skeleton
// compilation unit. We also inherit the Dwarf2Handler from
// the executable file, and call it as if we were still
// processing the original compilation unit.
void CompilationUnit::SetSplitDwarf(const uint8_t* addr_buffer,
uint64_t addr_buffer_length,
uint64_t addr_base,
uint64_t ranges_base,
uint64_t dwo_id) {
is_split_dwarf_ = true;
addr_buffer_ = addr_buffer;
addr_buffer_length_ = addr_buffer_length;
addr_base_ = addr_base;
ranges_base_ = ranges_base;
skeleton_dwo_id_ = dwo_id;
}
// Read a DWARF2/3 abbreviation section.
// Each abbrev consists of a abbreviation number, a tag, a byte
// specifying whether the tag has children, and a list of
// attribute/form pairs.
// The list of forms is terminated by a 0 for the attribute, and a
// zero for the form. The entire abbreviation section is terminated
// by a zero for the code.
void CompilationUnit::ReadAbbrevs() {
if (abbrevs_)
return;
// First get the debug_abbrev section.
SectionMap::const_iterator iter =
GetSectionByName(sections_, ".debug_abbrev");
assert(iter != sections_.end());
abbrevs_ = new std::vector<Abbrev>;
abbrevs_->resize(1);
// The only way to check whether we are reading over the end of the
// buffer would be to first compute the size of the leb128 data by
// reading it, then go back and read it again.
const uint8_t* abbrev_start = iter->second.first +
header_.abbrev_offset;
const uint8_t* abbrevptr = abbrev_start;
#ifndef NDEBUG
const uint64_t abbrev_length = iter->second.second - header_.abbrev_offset;
#endif
while (1) {
CompilationUnit::Abbrev abbrev;
size_t len;
const uint64_t number = reader_->ReadUnsignedLEB128(abbrevptr, &len);
if (number == 0)
break;
abbrev.number = number;
abbrevptr += len;
assert(abbrevptr < abbrev_start + abbrev_length);
const uint64_t tag = reader_->ReadUnsignedLEB128(abbrevptr, &len);
abbrevptr += len;
abbrev.tag = static_cast<enum DwarfTag>(tag);
assert(abbrevptr < abbrev_start + abbrev_length);
abbrev.has_children = reader_->ReadOneByte(abbrevptr);
abbrevptr += 1;
assert(abbrevptr < abbrev_start + abbrev_length);
while (1) {
const uint64_t nametemp = reader_->ReadUnsignedLEB128(abbrevptr, &len);
abbrevptr += len;
assert(abbrevptr < abbrev_start + abbrev_length);
const uint64_t formtemp = reader_->ReadUnsignedLEB128(abbrevptr, &len);
abbrevptr += len;
if (nametemp == 0 && formtemp == 0)
break;
const enum DwarfAttribute name =
static_cast<enum DwarfAttribute>(nametemp);
const enum DwarfForm form = static_cast<enum DwarfForm>(formtemp);
abbrev.attributes.push_back(std::make_pair(name, form));
}
assert(abbrev.number == abbrevs_->size());
abbrevs_->push_back(abbrev);
}
}
// Skips a single DIE's attributes.
const uint8_t* CompilationUnit::SkipDIE(const uint8_t* start,
const Abbrev& abbrev) {
for (AttributeList::const_iterator i = abbrev.attributes.begin();
i != abbrev.attributes.end();
i++) {
start = SkipAttribute(start, i->second);
}
return start;
}
// Skips a single attribute form's data.
const uint8_t* CompilationUnit::SkipAttribute(const uint8_t* start,
enum DwarfForm form) {
size_t len;
switch (form) {
case DW_FORM_indirect:
form = static_cast<enum DwarfForm>(reader_->ReadUnsignedLEB128(start,
&len));
start += len;
return SkipAttribute(start, form);
case DW_FORM_flag_present:
return start;
case DW_FORM_addrx1:
case DW_FORM_data1:
case DW_FORM_flag:
case DW_FORM_ref1:
case DW_FORM_strx1:
return start + 1;
case DW_FORM_addrx2:
case DW_FORM_ref2:
case DW_FORM_data2:
case DW_FORM_strx2:
return start + 2;
case DW_FORM_addrx3:
case DW_FORM_strx3:
return start + 3;
case DW_FORM_addrx4:
case DW_FORM_ref4:
case DW_FORM_data4:
case DW_FORM_strx4:
return start + 4;
case DW_FORM_ref8:
case DW_FORM_data8:
case DW_FORM_ref_sig8:
return start + 8;
case DW_FORM_string:
return start + strlen(reinterpret_cast<const char*>(start)) + 1;
case DW_FORM_udata:
case DW_FORM_ref_udata:
case DW_FORM_strx:
case DW_FORM_GNU_str_index:
case DW_FORM_GNU_addr_index:
case DW_FORM_addrx:
reader_->ReadUnsignedLEB128(start, &len);
return start + len;
case DW_FORM_sdata:
reader_->ReadSignedLEB128(start, &len);
return start + len;
case DW_FORM_addr:
return start + reader_->AddressSize();
case DW_FORM_ref_addr:
// DWARF2 and 3/4 differ on whether ref_addr is address size or
// offset size.
assert(header_.version >= 2);
if (header_.version == 2) {
return start + reader_->AddressSize();
} else if (header_.version >= 3) {
return start + reader_->OffsetSize();
}
break;
case DW_FORM_block1:
return start + 1 + reader_->ReadOneByte(start);
case DW_FORM_block2:
return start + 2 + reader_->ReadTwoBytes(start);
case DW_FORM_block4:
return start + 4 + reader_->ReadFourBytes(start);
case DW_FORM_block:
case DW_FORM_exprloc: {
uint64_t size = reader_->ReadUnsignedLEB128(start, &len);
return start + size + len;
}
case DW_FORM_strp:
case DW_FORM_line_strp:
case DW_FORM_strp_sup:
case DW_FORM_sec_offset:
return start + reader_->OffsetSize();
}
fprintf(stderr,"Unhandled form type");
return NULL;
}
// Read the abbreviation offset from a compilation unit header.
size_t CompilationUnit::ReadAbbrevOffset(const uint8_t* headerptr) {
assert(headerptr + reader_->OffsetSize() < buffer_ + buffer_length_);
header_.abbrev_offset = reader_->ReadOffset(headerptr);
return reader_->OffsetSize();
}
// Read the address size from a compilation unit header.
size_t CompilationUnit::ReadAddressSize(const uint8_t* headerptr) {
// Compare against less than or equal because this may be the last
// section in the file.
assert(headerptr + 1 <= buffer_ + buffer_length_);
header_.address_size = reader_->ReadOneByte(headerptr);
reader_->SetAddressSize(header_.address_size);
return 1;
}
// Read the DWO id from a split or skeleton compilation unit header.
size_t CompilationUnit::ReadDwoId(const uint8_t* headerptr) {
assert(headerptr + 8 <= buffer_ + buffer_length_);
dwo_id_ = reader_->ReadEightBytes(headerptr);
return 8;
}
// Read the type signature from a type or split type compilation unit header.
size_t CompilationUnit::ReadTypeSignature(const uint8_t* headerptr) {
assert(headerptr + 8 <= buffer_ + buffer_length_);
type_signature_ = reader_->ReadEightBytes(headerptr);
return 8;
}
// Read the DWO id from a split or skeleton compilation unit header.
size_t CompilationUnit::ReadTypeOffset(const uint8_t* headerptr) {
assert(headerptr + reader_->OffsetSize() < buffer_ + buffer_length_);
type_offset_ = reader_->ReadOffset(headerptr);
return reader_->OffsetSize();
}
// Read a DWARF header. The header is variable length in DWARF3 and DWARF4
// (and DWARF2 as extended by most compilers), and consists of an length
// field, a version number, the offset in the .debug_abbrev section for our
// abbrevs, and an address size. DWARF5 adds a unit_type to distinguish
// between partial-, full-, skeleton-, split-, and type- compilation units.
void CompilationUnit::ReadHeader() {
const uint8_t* headerptr = buffer_;
size_t initial_length_size;
assert(headerptr + 4 < buffer_ + buffer_length_);
const uint64_t initial_length
= reader_->ReadInitialLength(headerptr, &initial_length_size);
headerptr += initial_length_size;
header_.length = initial_length;
assert(headerptr + 2 < buffer_ + buffer_length_);
header_.version = reader_->ReadTwoBytes(headerptr);
headerptr += 2;
if (header_.version <= 4) {
// Older versions of dwarf have a relatively simple structure.
headerptr += ReadAbbrevOffset(headerptr);
headerptr += ReadAddressSize(headerptr);
} else {
// DWARF5 adds a unit_type field, and various fields based on unit_type.
assert(headerptr + 1 < buffer_ + buffer_length_);
uint8_t unit_type = reader_->ReadOneByte(headerptr);
headerptr += 1;
headerptr += ReadAddressSize(headerptr);
headerptr += ReadAbbrevOffset(headerptr);
switch (unit_type) {
case DW_UT_compile:
case DW_UT_partial:
// nothing else to read
break;
case DW_UT_skeleton:
case DW_UT_split_compile:
headerptr += ReadDwoId(headerptr);
break;
case DW_UT_type:
case DW_UT_split_type:
headerptr += ReadTypeSignature(headerptr);
headerptr += ReadTypeOffset(headerptr);
break;
default:
fprintf(stderr, "Unhandled compilation unit type 0x%x", unit_type);
break;
}
}
after_header_ = headerptr;
// This check ensures that we don't have to do checking during the
// reading of DIEs. header_.length does not include the size of the
// initial length.
assert(buffer_ + initial_length_size + header_.length <=
buffer_ + buffer_length_);
}
uint64_t CompilationUnit::Start() {
// First get the debug_info section.
SectionMap::const_iterator iter =
GetSectionByName(sections_, ".debug_info");
assert(iter != sections_.end());
// Set up our buffer
buffer_ = iter->second.first + offset_from_section_start_;
buffer_length_ = iter->second.second - offset_from_section_start_;
// Read the header
ReadHeader();
// Figure out the real length from the end of the initial length to
// the end of the compilation unit, since that is the value we
// return.
uint64_t ourlength = header_.length;
if (reader_->OffsetSize() == 8)
ourlength += 12;
else
ourlength += 4;
// See if the user wants this compilation unit, and if not, just return.
if (!handler_->StartCompilationUnit(offset_from_section_start_,
reader_->AddressSize(),
reader_->OffsetSize(),
header_.length,
header_.version))
return ourlength;
// Otherwise, continue by reading our abbreviation entries.
ReadAbbrevs();
// Set the string section if we have one.
iter = GetSectionByName(sections_, ".debug_str");
if (iter != sections_.end()) {
string_buffer_ = iter->second.first;
string_buffer_length_ = iter->second.second;
}
// Set the line string section if we have one.
iter = GetSectionByName(sections_, ".debug_line_str");
if (iter != sections_.end()) {
line_string_buffer_ = iter->second.first;
line_string_buffer_length_ = iter->second.second;
}
// Set the string offsets section if we have one.
iter = GetSectionByName(sections_, ".debug_str_offsets");
if (iter != sections_.end()) {
str_offsets_buffer_ = iter->second.first;
str_offsets_buffer_length_ = iter->second.second;
}
// Set the address section if we have one.
iter = GetSectionByName(sections_, ".debug_addr");
if (iter != sections_.end()) {
addr_buffer_ = iter->second.first;
addr_buffer_length_ = iter->second.second;
}
// Now that we have our abbreviations, start processing DIE's.
ProcessDIEs();
// If this is a skeleton compilation unit generated with split DWARF,
// and the client needs the full debug info, we need to find the full
// compilation unit in a .dwo or .dwp file.
if (!is_split_dwarf_
&& dwo_name_ != NULL
&& handler_->NeedSplitDebugInfo())
ProcessSplitDwarf();
return ourlength;
}
void CompilationUnit::ProcessFormStringIndex(
uint64_t dieoffset, enum DwarfAttribute attr, enum DwarfForm form,
uint64_t str_index) {
const uint8_t* offset_ptr =
str_offsets_buffer_ + str_index * reader_->OffsetSize();
const uint64_t offset = reader_->ReadOffset(offset_ptr);
if (offset >= string_buffer_length_) {
return;
}
const char* str = reinterpret_cast<const char*>(string_buffer_) + offset;
ProcessAttributeString(dieoffset, attr, form, str);
}
// If one really wanted, you could merge SkipAttribute and
// ProcessAttribute
// This is all boring data manipulation and calling of the handler.
const uint8_t* CompilationUnit::ProcessAttribute(
uint64_t dieoffset, const uint8_t* start, enum DwarfAttribute attr,
enum DwarfForm form) {
size_t len;
switch (form) {
// DW_FORM_indirect is never used because it is such a space
// waster.
case DW_FORM_indirect:
form = static_cast<enum DwarfForm>(reader_->ReadUnsignedLEB128(start,
&len));
start += len;
return ProcessAttribute(dieoffset, start, attr, form);
case DW_FORM_flag_present:
ProcessAttributeUnsigned(dieoffset, attr, form, 1);
return start;
case DW_FORM_data1:
case DW_FORM_flag:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadOneByte(start));
return start + 1;
case DW_FORM_data2:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadTwoBytes(start));
return start + 2;
case DW_FORM_data4:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadFourBytes(start));
return start + 4;
case DW_FORM_data8:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadEightBytes(start));
return start + 8;
case DW_FORM_string: {
const char* str = reinterpret_cast<const char*>(start);
ProcessAttributeString(dieoffset, attr, form, str);
return start + strlen(str) + 1;
}
case DW_FORM_udata:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadUnsignedLEB128(start, &len));
return start + len;
case DW_FORM_sdata:
ProcessAttributeSigned(dieoffset, attr, form,
reader_->ReadSignedLEB128(start, &len));
return start + len;
case DW_FORM_addr:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadAddress(start));
return start + reader_->AddressSize();
case DW_FORM_sec_offset:
ProcessAttributeUnsigned(dieoffset, attr, form,
reader_->ReadOffset(start));
return start + reader_->OffsetSize();
case DW_FORM_ref1:
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadOneByte(start)
+ offset_from_section_start_);
return start + 1;
case DW_FORM_ref2:
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadTwoBytes(start)
+ offset_from_section_start_);
return start + 2;
case DW_FORM_ref4:
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadFourBytes(start)
+ offset_from_section_start_);
return start + 4;
case DW_FORM_ref8:
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadEightBytes(start)
+ offset_from_section_start_);
return start + 8;
case DW_FORM_ref_udata:
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadUnsignedLEB128(start,
&len)
+ offset_from_section_start_);
return start + len;
case DW_FORM_ref_addr:
// DWARF2 and 3/4 differ on whether ref_addr is address size or
// offset size.
assert(header_.version >= 2);
if (header_.version == 2) {
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadAddress(start));
return start + reader_->AddressSize();
} else if (header_.version >= 3) {
handler_->ProcessAttributeReference(dieoffset, attr, form,
reader_->ReadOffset(start));
return start + reader_->OffsetSize();
}
break;
case DW_FORM_ref_sig8:
handler_->ProcessAttributeSignature(dieoffset, attr, form,
reader_->ReadEightBytes(start));
return start + 8;
case DW_FORM_block1: {
uint64_t datalen = reader_->ReadOneByte(start);
handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 1,
datalen);
return start + 1 + datalen;
}
case DW_FORM_block2: {
uint64_t datalen = reader_->ReadTwoBytes(start);
handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 2,
datalen);
return start + 2 + datalen;
}
case DW_FORM_block4: {
uint64_t datalen = reader_->ReadFourBytes(start);
handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + 4,
datalen);
return start + 4 + datalen;
}
case DW_FORM_block:
case DW_FORM_exprloc: {
uint64_t datalen = reader_->ReadUnsignedLEB128(start, &len);
handler_->ProcessAttributeBuffer(dieoffset, attr, form, start + len,
datalen);
return start + datalen + len;
}
case DW_FORM_strp: {
assert(string_buffer_ != NULL);
const uint64_t offset = reader_->ReadOffset(start);
assert(string_buffer_ + offset < string_buffer_ + string_buffer_length_);
const char* str = reinterpret_cast<const char*>(string_buffer_ + offset);
ProcessAttributeString(dieoffset, attr, form, str);
return start + reader_->OffsetSize();
}
case DW_FORM_line_strp: {
assert(line_string_buffer_ != NULL);
const uint64_t offset = reader_->ReadOffset(start);
assert(line_string_buffer_ + offset <
line_string_buffer_ + line_string_buffer_length_);
const char* str =
reinterpret_cast<const char*>(line_string_buffer_ + offset);
ProcessAttributeString(dieoffset, attr, form, str);
return start + reader_->OffsetSize();
}
case DW_FORM_strp_sup:
// No support currently for suplementary object files.
fprintf(stderr, "Unhandled form type: DW_FORM_strp_sup\n");
return start + 4;
case DW_FORM_strx:
case DW_FORM_GNU_str_index: {
uint64_t str_index = reader_->ReadUnsignedLEB128(start, &len);
ProcessFormStringIndex(dieoffset, attr, form, str_index);
return start + len;
}
case DW_FORM_strx1: {
uint64_t str_index = reader_->ReadOneByte(start);
ProcessFormStringIndex(dieoffset, attr, form, str_index);
return start + 1;
}
case DW_FORM_strx2: {
uint64_t str_index = reader_->ReadTwoBytes(start);
ProcessFormStringIndex(dieoffset, attr, form, str_index);
return start + 2;
}
case DW_FORM_strx3: {
uint64_t str_index = reader_->ReadThreeBytes(start);
ProcessFormStringIndex(dieoffset, attr, form, str_index);
return start + 3;
}
case DW_FORM_strx4: {
uint64_t str_index = reader_->ReadFourBytes(start);
ProcessFormStringIndex(dieoffset, attr, form, str_index);
return start + 4;
}
case DW_FORM_addrx:
case DW_FORM_GNU_addr_index:
ProcessAttributeAddrIndex(
dieoffset, attr, form, reader_->ReadUnsignedLEB128(start, &len));
return start + len;
case DW_FORM_addrx1:
ProcessAttributeAddrIndex(
dieoffset, attr, form, reader_->ReadOneByte(start));
return start + 1;
case DW_FORM_addrx2:
ProcessAttributeAddrIndex(
dieoffset, attr, form, reader_->ReadTwoBytes(start));
return start + 2;
case DW_FORM_addrx3:
ProcessAttributeAddrIndex(
dieoffset, attr, form, reader_->ReadThreeBytes(start));
return start + 3;
case DW_FORM_addrx4:
ProcessAttributeAddrIndex(
dieoffset, attr, form, reader_->ReadFourBytes(start));
return start + 4;
}
fprintf(stderr, "Unhandled form type\n");
return NULL;
}
const uint8_t* CompilationUnit::ProcessDIE(uint64_t dieoffset,
const uint8_t* start,
const Abbrev& abbrev) {
for (AttributeList::const_iterator i = abbrev.attributes.begin();
i != abbrev.attributes.end();
i++) {
start = ProcessAttribute(dieoffset, start, i->first, i->second);
}
// If this is a compilation unit in a split DWARF object, verify that
// the dwo_id matches. If it does not match, we will ignore this
// compilation unit.
if (abbrev.tag == DW_TAG_compile_unit
&& is_split_dwarf_
&& dwo_id_ != skeleton_dwo_id_) {
return NULL;
}
return start;
}
void CompilationUnit::ProcessDIEs() {
const uint8_t* dieptr = after_header_;
size_t len;
// lengthstart is the place the length field is based on.
// It is the point in the header after the initial length field
const uint8_t* lengthstart = buffer_;
// In 64 bit dwarf, the initial length is 12 bytes, because of the
// 0xffffffff at the start.
if (reader_->OffsetSize() == 8)
lengthstart += 12;
else
lengthstart += 4;
std::stack<uint64_t> die_stack;
while (dieptr < (lengthstart + header_.length)) {
// We give the user the absolute offset from the beginning of
// debug_info, since they need it to deal with ref_addr forms.
uint64_t absolute_offset = (dieptr - buffer_) + offset_from_section_start_;
uint64_t abbrev_num = reader_->ReadUnsignedLEB128(dieptr, &len);
dieptr += len;
// Abbrev == 0 represents the end of a list of children, or padding
// at the end of the compilation unit.
if (abbrev_num == 0) {
if (die_stack.size() == 0)
// If it is padding, then we are done with the compilation unit's DIEs.
return;
const uint64_t offset = die_stack.top();
die_stack.pop();
handler_->EndDIE(offset);
continue;
}
const Abbrev& abbrev = abbrevs_->at(static_cast<size_t>(abbrev_num));
const enum DwarfTag tag = abbrev.tag;
if (!handler_->StartDIE(absolute_offset, tag)) {
dieptr = SkipDIE(dieptr, abbrev);
} else {
dieptr = ProcessDIE(absolute_offset, dieptr, abbrev);
}
if (abbrev.has_children) {
die_stack.push(absolute_offset);
} else {
handler_->EndDIE(absolute_offset);
}
}
}
// Check for a valid ELF file and return the Address size.
// Returns 0 if not a valid ELF file.
inline int GetElfWidth(const ElfReader& elf) {
if (elf.IsElf32File())
return 4;
if (elf.IsElf64File())
return 8;
return 0;
}
void CompilationUnit::ProcessSplitDwarf() {
struct stat statbuf;
if (!have_checked_for_dwp_) {
// Look for a .dwp file in the same directory as the executable.
have_checked_for_dwp_ = true;
string dwp_suffix(".dwp");
dwp_path_ = path_ + dwp_suffix;
if (stat(dwp_path_.c_str(), &statbuf) != 0) {
// Fall back to a split .debug file in the same directory.
string debug_suffix(".debug");
dwp_path_ = path_;
size_t found = path_.rfind(debug_suffix);
if (found + debug_suffix.length() == path_.length())
dwp_path_ = dwp_path_.replace(found, debug_suffix.length(), dwp_suffix);
}
if (stat(dwp_path_.c_str(), &statbuf) == 0) {
ElfReader* elf = new ElfReader(dwp_path_);
int width = GetElfWidth(*elf);
if (width != 0) {
dwp_byte_reader_.reset(new ByteReader(reader_->GetEndianness()));
dwp_byte_reader_->SetAddressSize(width);
dwp_reader_.reset(new DwpReader(*dwp_byte_reader_, elf));
dwp_reader_->Initialize();
} else {
delete elf;
}
}
}
bool found_in_dwp = false;
if (dwp_reader_) {
// If we have a .dwp file, read the debug sections for the requested CU.
SectionMap sections;
dwp_reader_->ReadDebugSectionsForCU(dwo_id_, &sections);
if (!sections.empty()) {
found_in_dwp = true;
CompilationUnit dwp_comp_unit(dwp_path_, sections, 0,
dwp_byte_reader_.get(), handler_);
dwp_comp_unit.SetSplitDwarf(addr_buffer_, addr_buffer_length_, addr_base_,
ranges_base_, dwo_id_);
dwp_comp_unit.Start();
}
}
if (!found_in_dwp) {
// If no .dwp file, try to open the .dwo file.
if (stat(dwo_name_, &statbuf) == 0) {
ElfReader elf(dwo_name_);
int width = GetElfWidth(elf);
if (width != 0) {
ByteReader reader(ENDIANNESS_LITTLE);
reader.SetAddressSize(width);
SectionMap sections;
ReadDebugSectionsFromDwo(&elf, &sections);
CompilationUnit dwo_comp_unit(dwo_name_, sections, 0, &reader,
handler_);
dwo_comp_unit.SetSplitDwarf(addr_buffer_, addr_buffer_length_,
addr_base_, ranges_base_, dwo_id_);
dwo_comp_unit.Start();
}
}
}
}
void CompilationUnit::ReadDebugSectionsFromDwo(ElfReader* elf_reader,
SectionMap* sections) {
static const char* const section_names[] = {
".debug_abbrev",
".debug_info",
".debug_str_offsets",
".debug_str"
};
for (unsigned int i = 0u;
i < sizeof(section_names)/sizeof(*(section_names)); ++i) {
string base_name = section_names[i];
string dwo_name = base_name + ".dwo";
size_t section_size;
const char* section_data = elf_reader->GetSectionByName(dwo_name,
&section_size);
if (section_data != NULL)
sections->insert(std::make_pair(
base_name, std::make_pair(
reinterpret_cast<const uint8_t*>(section_data),
section_size)));
}
}
DwpReader::DwpReader(const ByteReader& byte_reader, ElfReader* elf_reader)
: elf_reader_(elf_reader), byte_reader_(byte_reader),
cu_index_(NULL), cu_index_size_(0), string_buffer_(NULL),
string_buffer_size_(0), version_(0), ncolumns_(0), nunits_(0),
nslots_(0), phash_(NULL), pindex_(NULL), shndx_pool_(NULL),
offset_table_(NULL), size_table_(NULL), abbrev_data_(NULL),
abbrev_size_(0), info_data_(NULL), info_size_(0),
str_offsets_data_(NULL), str_offsets_size_(0) {}
DwpReader::~DwpReader() {
if (elf_reader_) delete elf_reader_;
}
void DwpReader::Initialize() {
cu_index_ = elf_reader_->GetSectionByName(".debug_cu_index",
&cu_index_size_);
if (cu_index_ == NULL) {
return;
}
// The .debug_str.dwo section is shared by all CUs in the file.
string_buffer_ = elf_reader_->GetSectionByName(".debug_str.dwo",
&string_buffer_size_);
version_ = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(cu_index_));
if (version_ == 1) {
nslots_ = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(cu_index_)
+ 3 * sizeof(uint32_t));
phash_ = cu_index_ + 4 * sizeof(uint32_t);
pindex_ = phash_ + nslots_ * sizeof(uint64_t);
shndx_pool_ = pindex_ + nslots_ * sizeof(uint32_t);
if (shndx_pool_ >= cu_index_ + cu_index_size_) {
version_ = 0;
}
} else if (version_ == 2) {
ncolumns_ = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(cu_index_) + sizeof(uint32_t));
nunits_ = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(cu_index_) + 2 * sizeof(uint32_t));
nslots_ = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(cu_index_) + 3 * sizeof(uint32_t));
phash_ = cu_index_ + 4 * sizeof(uint32_t);
pindex_ = phash_ + nslots_ * sizeof(uint64_t);
offset_table_ = pindex_ + nslots_ * sizeof(uint32_t);
size_table_ = offset_table_ + ncolumns_ * (nunits_ + 1) * sizeof(uint32_t);
abbrev_data_ = elf_reader_->GetSectionByName(".debug_abbrev.dwo",
&abbrev_size_);
info_data_ = elf_reader_->GetSectionByName(".debug_info.dwo", &info_size_);
str_offsets_data_ = elf_reader_->GetSectionByName(".debug_str_offsets.dwo",
&str_offsets_size_);
if (size_table_ >= cu_index_ + cu_index_size_) {
version_ = 0;
}
}
}
void DwpReader::ReadDebugSectionsForCU(uint64_t dwo_id,
SectionMap* sections) {
if (version_ == 1) {
int slot = LookupCU(dwo_id);
if (slot == -1) {
return;
}
// The index table points to the section index pool, where we
// can read a list of section indexes for the debug sections
// for the CU whose dwo_id we are looking for.
int index = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(pindex_)
+ slot * sizeof(uint32_t));
const char* shndx_list = shndx_pool_ + index * sizeof(uint32_t);
for (;;) {
if (shndx_list >= cu_index_ + cu_index_size_) {
version_ = 0;
return;
}
unsigned int shndx = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(shndx_list));
shndx_list += sizeof(uint32_t);
if (shndx == 0)
break;
const char* section_name = elf_reader_->GetSectionName(shndx);
size_t section_size;
const char* section_data;
// We're only interested in these four debug sections.
// The section names in the .dwo file end with ".dwo", but we
// add them to the sections table with their normal names.
if (!strncmp(section_name, ".debug_abbrev", strlen(".debug_abbrev"))) {
section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
sections->insert(std::make_pair(
".debug_abbrev",
std::make_pair(reinterpret_cast<const uint8_t*> (section_data),
section_size)));
} else if (!strncmp(section_name, ".debug_info", strlen(".debug_info"))) {
section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
sections->insert(std::make_pair(
".debug_info",
std::make_pair(reinterpret_cast<const uint8_t*> (section_data),
section_size)));
} else if (!strncmp(section_name, ".debug_str_offsets",
strlen(".debug_str_offsets"))) {
section_data = elf_reader_->GetSectionByIndex(shndx, &section_size);
sections->insert(std::make_pair(
".debug_str_offsets",
std::make_pair(reinterpret_cast<const uint8_t*> (section_data),
section_size)));
}
}
sections->insert(std::make_pair(
".debug_str",
std::make_pair(reinterpret_cast<const uint8_t*> (string_buffer_),
string_buffer_size_)));
} else if (version_ == 2) {
uint32_t index = LookupCUv2(dwo_id);
if (index == 0) {
return;
}
// The index points to a row in each of the section offsets table
// and the section size table, where we can read the offsets and sizes
// of the contributions to each debug section from the CU whose dwo_id
// we are looking for. Row 0 of the section offsets table has the
// section ids for each column of the table. The size table begins
// with row 1.
const char* id_row = offset_table_;
const char* offset_row = offset_table_
+ index * ncolumns_ * sizeof(uint32_t);
const char* size_row =
size_table_ + (index - 1) * ncolumns_ * sizeof(uint32_t);
if (size_row + ncolumns_ * sizeof(uint32_t) > cu_index_ + cu_index_size_) {
version_ = 0;
return;
}
for (unsigned int col = 0u; col < ncolumns_; ++col) {
uint32_t section_id =
byte_reader_.ReadFourBytes(reinterpret_cast<const uint8_t*>(id_row)
+ col * sizeof(uint32_t));
uint32_t offset = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(offset_row)
+ col * sizeof(uint32_t));
uint32_t size = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(size_row) + col * sizeof(uint32_t));
if (section_id == DW_SECT_ABBREV) {
sections->insert(std::make_pair(
".debug_abbrev",
std::make_pair(reinterpret_cast<const uint8_t*> (abbrev_data_)
+ offset, size)));
} else if (section_id == DW_SECT_INFO) {
sections->insert(std::make_pair(
".debug_info",
std::make_pair(reinterpret_cast<const uint8_t*> (info_data_)
+ offset, size)));
} else if (section_id == DW_SECT_STR_OFFSETS) {
sections->insert(std::make_pair(
".debug_str_offsets",
std::make_pair(reinterpret_cast<const uint8_t*> (str_offsets_data_)
+ offset, size)));
}
}
sections->insert(std::make_pair(
".debug_str",
std::make_pair(reinterpret_cast<const uint8_t*> (string_buffer_),
string_buffer_size_)));
}
}
int DwpReader::LookupCU(uint64_t dwo_id) {
uint32_t slot = static_cast<uint32_t>(dwo_id) & (nslots_ - 1);
uint64_t probe = byte_reader_.ReadEightBytes(
reinterpret_cast<const uint8_t*>(phash_) + slot * sizeof(uint64_t));
if (probe != 0 && probe != dwo_id) {
uint32_t secondary_hash =
(static_cast<uint32_t>(dwo_id >> 32) & (nslots_ - 1)) | 1;
do {
slot = (slot + secondary_hash) & (nslots_ - 1);
probe = byte_reader_.ReadEightBytes(
reinterpret_cast<const uint8_t*>(phash_) + slot * sizeof(uint64_t));
} while (probe != 0 && probe != dwo_id);
}
if (probe == 0)
return -1;
return slot;
}
uint32_t DwpReader::LookupCUv2(uint64_t dwo_id) {
uint32_t slot = static_cast<uint32_t>(dwo_id) & (nslots_ - 1);
uint64_t probe = byte_reader_.ReadEightBytes(
reinterpret_cast<const uint8_t*>(phash_) + slot * sizeof(uint64_t));
uint32_t index = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(pindex_) + slot * sizeof(uint32_t));
if (index != 0 && probe != dwo_id) {
uint32_t secondary_hash =
(static_cast<uint32_t>(dwo_id >> 32) & (nslots_ - 1)) | 1;
do {
slot = (slot + secondary_hash) & (nslots_ - 1);
probe = byte_reader_.ReadEightBytes(
reinterpret_cast<const uint8_t*>(phash_) + slot * sizeof(uint64_t));
index = byte_reader_.ReadFourBytes(
reinterpret_cast<const uint8_t*>(pindex_) + slot * sizeof(uint32_t));
} while (index != 0 && probe != dwo_id);
}
return index;
}
LineInfo::LineInfo(const uint8_t* buffer, uint64_t buffer_length,
ByteReader* reader, const uint8_t* string_buffer,
size_t string_buffer_length,
const uint8_t* line_string_buffer,
size_t line_string_buffer_length, LineInfoHandler* handler):
handler_(handler), reader_(reader), buffer_(buffer),
string_buffer_(string_buffer),
line_string_buffer_(line_string_buffer) {
#ifndef NDEBUG
buffer_length_ = buffer_length;
string_buffer_length_ = string_buffer_length;
line_string_buffer_length_ = line_string_buffer_length;
#endif
header_.std_opcode_lengths = NULL;
}
uint64_t LineInfo::Start() {
ReadHeader();
ReadLines();
return after_header_ - buffer_;
}
void LineInfo::ReadTypesAndForms(const uint8_t** lineptr,
uint32_t* content_types,
uint32_t* content_forms,
uint32_t max_types,
uint32_t* format_count) {
size_t len;
uint32_t count = reader_->ReadUnsignedLEB128(*lineptr, &len);
*lineptr += len;
if (count < 1 || count > max_types) {
return;
}
for (uint32_t col = 0; col < count; ++col) {
content_types[col] = reader_->ReadUnsignedLEB128(*lineptr, &len);
*lineptr += len;
content_forms[col] = reader_->ReadUnsignedLEB128(*lineptr, &len);
*lineptr += len;
}
*format_count = count;
}
const char* LineInfo::ReadStringForm(uint32_t form, const uint8_t** lineptr) {
const char* name = nullptr;
if (form == DW_FORM_string) {
name = reinterpret_cast<const char*>(*lineptr);
*lineptr += strlen(name) + 1;
return name;
} else if (form == DW_FORM_strp) {
uint64_t offset = reader_->ReadOffset(*lineptr);
assert(offset < string_buffer_length_);
*lineptr += reader_->OffsetSize();
if (string_buffer_ != nullptr) {
name = reinterpret_cast<const char*>(string_buffer_) + offset;
return name;
}
} else if (form == DW_FORM_line_strp) {
uint64_t offset = reader_->ReadOffset(*lineptr);
assert(offset < line_string_buffer_length_);
*lineptr += reader_->OffsetSize();
if (line_string_buffer_ != nullptr) {
name = reinterpret_cast<const char*>(line_string_buffer_) + offset;
return name;
}
}
// Shouldn't be called with a non-string-form, and
// if there is a string form but no string buffer,
// that is a problem too.
assert(0);
return nullptr;
}
uint64_t LineInfo::ReadUnsignedData(uint32_t form, const uint8_t** lineptr) {
size_t len;
uint64_t value;
switch (form) {
case DW_FORM_data1:
value = reader_->ReadOneByte(*lineptr);
*lineptr += 1;
return value;
case DW_FORM_data2:
value = reader_->ReadTwoBytes(*lineptr);
*lineptr += 2;
return value;
case DW_FORM_data4:
value = reader_->ReadFourBytes(*lineptr);
*lineptr += 4;
return value;
case DW_FORM_data8:
value = reader_->ReadEightBytes(*lineptr);
*lineptr += 8;
return value;
case DW_FORM_udata:
value = reader_->ReadUnsignedLEB128(*lineptr, &len);
*lineptr += len;
return value;
default:
fprintf(stderr, "Unrecognized data form.");
return 0;
}
}
void LineInfo::ReadFileRow(const uint8_t** lineptr,
const uint32_t* content_types,
const uint32_t* content_forms, uint32_t row,
uint32_t format_count) {
const char* filename = nullptr;
uint64_t dirindex = 0;
uint64_t mod_time = 0;
uint64_t filelength = 0;
for (uint32_t col = 0; col < format_count; ++col) {
switch (content_types[col]) {
case DW_LNCT_path:
filename = ReadStringForm(content_forms[col], lineptr);
break;
case DW_LNCT_directory_index:
dirindex = ReadUnsignedData(content_forms[col], lineptr);
break;
case DW_LNCT_timestamp:
mod_time = ReadUnsignedData(content_forms[col], lineptr);
break;
case DW_LNCT_size:
filelength = ReadUnsignedData(content_forms[col], lineptr);
break;
case DW_LNCT_MD5:
// MD5 entries help a debugger sort different versions of files with
// the same name. It is always paired with a DW_FORM_data16 and is
// unused in this case.
lineptr += 16;
break;
default:
fprintf(stderr, "Unrecognized form in line table header. %d\n",
content_types[col]);
assert(false);
break;
}
}
assert(filename != nullptr);
handler_->DefineFile(filename, row, dirindex, mod_time, filelength);
}
// The header for a debug_line section is mildly complicated, because
// the line info is very tightly encoded.
void LineInfo::ReadHeader() {
const uint8_t* lineptr = buffer_;
size_t initial_length_size;
const uint64_t initial_length
= reader_->ReadInitialLength(lineptr, &initial_length_size);
lineptr += initial_length_size;
header_.total_length = initial_length;
assert(buffer_ + initial_length_size + header_.total_length <=
buffer_ + buffer_length_);
header_.version = reader_->ReadTwoBytes(lineptr);
lineptr += 2;
if (header_.version >= 5) {
uint8_t address_size = reader_->ReadOneByte(lineptr);
reader_->SetAddressSize(address_size);
lineptr += 1;
uint8_t segment_selector_size = reader_->ReadOneByte(lineptr);
if (segment_selector_size != 0) {
fprintf(stderr,"No support for segmented memory.");
}
lineptr += 1;
} else {
// Address size *must* be set by CU ahead of time.
assert(reader_->AddressSize() != 0);
}
header_.prologue_length = reader_->ReadOffset(lineptr);
lineptr += reader_->OffsetSize();
header_.min_insn_length = reader_->ReadOneByte(lineptr);
lineptr += 1;
if (header_.version >= 4) {
__attribute__((unused)) uint8_t max_ops_per_insn =
reader_->ReadOneByte(lineptr);
++lineptr;
assert(max_ops_per_insn == 1);
}
header_.default_is_stmt = reader_->ReadOneByte(lineptr);
lineptr += 1;
header_.line_base = *reinterpret_cast<const int8_t*>(lineptr);
lineptr += 1;
header_.line_range = reader_->ReadOneByte(lineptr);
lineptr += 1;
header_.opcode_base = reader_->ReadOneByte(lineptr);
lineptr += 1;
header_.std_opcode_lengths = new std::vector<unsigned char>;
header_.std_opcode_lengths->resize(header_.opcode_base + 1);
(*header_.std_opcode_lengths)[0] = 0;
for (int i = 1; i < header_.opcode_base; i++) {
(*header_.std_opcode_lengths)[i] = reader_->ReadOneByte(lineptr);
lineptr += 1;
}
if (header_.version <= 4) {
// Directory zero is assumed to be the compilation directory and special
// cased where used. It is not actually stored in the dwarf data. But an
// empty entry here avoids off-by-one errors elsewhere in the code.
handler_->DefineDir("", 0);
// It is legal for the directory entry table to be empty.
if (*lineptr) {
uint32_t dirindex = 1;
while (*lineptr) {
const char* dirname = reinterpret_cast<const char*>(lineptr);
handler_->DefineDir(dirname, dirindex);
lineptr += strlen(dirname) + 1;
dirindex++;
}
}
lineptr++;
// It is also legal for the file entry table to be empty.
// Similarly for file zero.
handler_->DefineFile("", 0, 0, 0, 0);
if (*lineptr) {
uint32_t fileindex = 1;
size_t len;
while (*lineptr) {
const char* filename = ReadStringForm(DW_FORM_string, &lineptr);
uint64_t dirindex = reader_->ReadUnsignedLEB128(lineptr, &len);
lineptr += len;
uint64_t mod_time = reader_->ReadUnsignedLEB128(lineptr, &len);
lineptr += len;
uint64_t filelength = reader_->ReadUnsignedLEB128(lineptr, &len);
lineptr += len;
handler_->DefineFile(filename, fileindex,
static_cast<uint32_t>(dirindex), mod_time,
filelength);
fileindex++;
}
}
lineptr++;
} else {
// Read the DWARF-5 directory table.
// Dwarf5 supports five different types and forms per directory- and
// file-table entry. Theoretically, there could be duplicate entries
// in this table, but that would be quite unusual.
static const uint32_t kMaxTypesAndForms = 5;
uint32_t content_types[kMaxTypesAndForms];
uint32_t content_forms[kMaxTypesAndForms];
uint32_t format_count;
size_t len;
ReadTypesAndForms(&lineptr, content_types, content_forms, kMaxTypesAndForms,
&format_count);
uint32_t entry_count = reader_->ReadUnsignedLEB128(lineptr, &len);
lineptr += len;
for (uint32_t row = 0; row < entry_count; ++row) {
const char* dirname = nullptr;
for (uint32_t col = 0; col < format_count; ++col) {
// The path is the only relevant content type for this implementation.
if (content_types[col] == DW_LNCT_path) {
dirname = ReadStringForm(content_forms[col], &lineptr);
}
}
handler_->DefineDir(dirname, row);
}
// Read the DWARF-5 filename table.
ReadTypesAndForms(&lineptr, content_types, content_forms, kMaxTypesAndForms,
&format_count);
entry_count = reader_->ReadUnsignedLEB128(lineptr, &len);
lineptr += len;
for (uint32_t row = 0; row < entry_count; ++row) {
ReadFileRow(&lineptr, content_types, content_forms, row, format_count);
}
}
after_header_ = lineptr;
}
/* static */
bool LineInfo::ProcessOneOpcode(ByteReader* reader,
LineInfoHandler* handler,
const struct LineInfoHeader& header,
const uint8_t* start,
struct LineStateMachine* lsm,
size_t* len,
uintptr pc,
bool* lsm_passes_pc) {
size_t oplen = 0;
size_t templen;
uint8_t opcode = reader->ReadOneByte(start);
oplen++;
start++;
// If the opcode is great than the opcode_base, it is a special
// opcode. Most line programs consist mainly of special opcodes.
if (opcode >= header.opcode_base) {
opcode -= header.opcode_base;
const int64_t advance_address = (opcode / header.line_range)
* header.min_insn_length;
const int32_t advance_line = (opcode % header.line_range)
+ header.line_base;
// Check if the lsm passes "pc". If so, mark it as passed.
if (lsm_passes_pc &&
lsm->address <= pc && pc < lsm->address + advance_address) {
*lsm_passes_pc = true;
}
lsm->address += advance_address;
lsm->line_num += advance_line;
lsm->basic_block = true;
*len = oplen;
return true;
}
// Otherwise, we have the regular opcodes
switch (opcode) {
case DW_LNS_copy: {
lsm->basic_block = false;
*len = oplen;
return true;
}
case DW_LNS_advance_pc: {
uint64_t advance_address = reader->ReadUnsignedLEB128(start, &templen);
oplen += templen;
// Check if the lsm passes "pc". If so, mark it as passed.
if (lsm_passes_pc && lsm->address <= pc &&
pc < lsm->address + header.min_insn_length * advance_address) {
*lsm_passes_pc = true;
}
lsm->address += header.min_insn_length * advance_address;
}
break;
case DW_LNS_advance_line: {
const int64_t advance_line = reader->ReadSignedLEB128(start, &templen);
oplen += templen;
lsm->line_num += static_cast<int32_t>(advance_line);
// With gcc 4.2.1, we can get the line_no here for the first time
// since DW_LNS_advance_line is called after DW_LNE_set_address is
// called. So we check if the lsm passes "pc" here, not in
// DW_LNE_set_address.
if (lsm_passes_pc && lsm->address == pc) {
*lsm_passes_pc = true;
}
}
break;
case DW_LNS_set_file: {
const uint64_t fileno = reader->ReadUnsignedLEB128(start, &templen);
oplen += templen;
lsm->file_num = static_cast<uint32_t>(fileno);
}
break;
case DW_LNS_set_column: {
const uint64_t colno = reader->ReadUnsignedLEB128(start, &templen);
oplen += templen;
lsm->column_num = static_cast<uint32_t>(colno);
}
break;
case DW_LNS_negate_stmt: {
lsm->is_stmt = !lsm->is_stmt;
}
break;
case DW_LNS_set_basic_block: {
lsm->basic_block = true;
}
break;
case DW_LNS_fixed_advance_pc: {
const uint16_t advance_address = reader->ReadTwoBytes(start);
oplen += 2;
// Check if the lsm passes "pc". If so, mark it as passed.
if (lsm_passes_pc &&
lsm->address <= pc && pc < lsm->address + advance_address) {
*lsm_passes_pc = true;
}
lsm->address += advance_address;
}
break;
case DW_LNS_const_add_pc: {
const int64_t advance_address = header.min_insn_length
* ((255 - header.opcode_base)
/ header.line_range);
// Check if the lsm passes "pc". If so, mark it as passed.
if (lsm_passes_pc &&
lsm->address <= pc && pc < lsm->address + advance_address) {
*lsm_passes_pc = true;
}
lsm->address += advance_address;
}
break;
case DW_LNS_extended_op: {
const uint64_t extended_op_len = reader->ReadUnsignedLEB128(start,
&templen);
start += templen;
oplen += templen + extended_op_len;
const uint64_t extended_op = reader->ReadOneByte(start);
start++;
switch (extended_op) {
case DW_LNE_end_sequence: {
lsm->end_sequence = true;
*len = oplen;
return true;
}
break;
case DW_LNE_set_address: {
// With gcc 4.2.1, we cannot tell the line_no here since
// DW_LNE_set_address is called before DW_LNS_advance_line is
// called. So we do not check if the lsm passes "pc" here. See
// also the comment in DW_LNS_advance_line.
uint64_t address = reader->ReadAddress(start);
lsm->address = address;
}
break;
case DW_LNE_define_file: {
const char* filename = reinterpret_cast<const char*>(start);
templen = strlen(filename) + 1;
start += templen;
uint64_t dirindex = reader->ReadUnsignedLEB128(start, &templen);
oplen += templen;
const uint64_t mod_time = reader->ReadUnsignedLEB128(start,
&templen);
oplen += templen;
const uint64_t filelength = reader->ReadUnsignedLEB128(start,
&templen);
oplen += templen;
if (handler) {
handler->DefineFile(filename, -1, static_cast<uint32_t>(dirindex),
mod_time, filelength);
}
}
break;
}
}
break;
default: {
// Ignore unknown opcode silently
if (header.std_opcode_lengths) {
for (int i = 0; i < (*header.std_opcode_lengths)[opcode]; i++) {
reader->ReadUnsignedLEB128(start, &templen);
start += templen;
oplen += templen;
}
}
}
break;
}
*len = oplen;
return false;
}
void LineInfo::ReadLines() {
struct LineStateMachine lsm;
// lengthstart is the place the length field is based on.
// It is the point in the header after the initial length field
const uint8_t* lengthstart = buffer_;
// In 64 bit dwarf, the initial length is 12 bytes, because of the
// 0xffffffff at the start.
if (reader_->OffsetSize() == 8)
lengthstart += 12;
else
lengthstart += 4;
const uint8_t* lineptr = after_header_;
lsm.Reset(header_.default_is_stmt);
// The LineInfoHandler interface expects each line's length along
// with its address, but DWARF only provides addresses (sans
// length), and an end-of-sequence address; one infers the length
// from the next address. So we report a line only when we get the
// next line's address, or the end-of-sequence address.
bool have_pending_line = false;
uint64_t pending_address = 0;
uint32_t pending_file_num = 0, pending_line_num = 0, pending_column_num = 0;
while (lineptr < lengthstart + header_.total_length) {
size_t oplength;
bool add_row = ProcessOneOpcode(reader_, handler_, header_,
lineptr, &lsm, &oplength, (uintptr)-1,
NULL);
if (add_row) {
if (have_pending_line)
handler_->AddLine(pending_address, lsm.address - pending_address,
pending_file_num, pending_line_num,
pending_column_num);
if (lsm.end_sequence) {
lsm.Reset(header_.default_is_stmt);
have_pending_line = false;
} else {
pending_address = lsm.address;
pending_file_num = lsm.file_num;
pending_line_num = lsm.line_num;
pending_column_num = lsm.column_num;
have_pending_line = true;
}
}
lineptr += oplength;
}
after_header_ = lengthstart + header_.total_length;
}
RangeListReader::RangeListReader(const uint8_t* buffer, uint64_t size,
ByteReader* reader)
: buffer_(buffer), size_(size), reader_(reader) { }
bool RangeListReader::ReadRangeList(uint64_t offset,
RangeListHandler* handler) {
const uint64_t max_address =
(reader_->AddressSize() == 4) ? 0xffffffffUL
: 0xffffffffffffffffULL;
const uint64_t entry_size = reader_->AddressSize() * 2;
bool list_end = false;
do {
if (offset > size_ - entry_size) {
return false; // Invalid range detected
}
uint64_t start_address = reader_->ReadAddress(buffer_ + offset);
uint64_t end_address =
reader_->ReadAddress(buffer_ + offset + reader_->AddressSize());
if (start_address == max_address) { // Base address selection
handler->SetBaseAddress(end_address);
} else if (start_address == 0 && end_address == 0) { // End-of-list
handler->Finish();
list_end = true;
} else { // Add a range entry
handler->AddRange(start_address, end_address);
}
offset += entry_size;
} while (!list_end);
return true;
}
// A DWARF rule for recovering the address or value of a register, or
// computing the canonical frame address. There is one subclass of this for
// each '*Rule' member function in CallFrameInfo::Handler.
//
// It's annoying that we have to handle Rules using pointers (because
// the concrete instances can have an arbitrary size). They're small,
// so it would be much nicer if we could just handle them by value
// instead of fretting about ownership and destruction.
//
// It seems like all these could simply be instances of std::tr1::bind,
// except that we need instances to be EqualityComparable, too.
//
// This could logically be nested within State, but then the qualified names
// get horrendous.
class CallFrameInfo::Rule {
public:
virtual ~Rule() { }
// Tell HANDLER that, at ADDRESS in the program, REG can be recovered using
// this rule. If REG is kCFARegister, then this rule describes how to compute
// the canonical frame address. Return what the HANDLER member function
// returned.
virtual bool Handle(Handler* handler,
uint64_t address, int reg) const = 0;
// Equality on rules. We use these to decide which rules we need
// to report after a DW_CFA_restore_state instruction.
virtual bool operator==(const Rule& rhs) const = 0;
bool operator!=(const Rule& rhs) const { return ! (*this == rhs); }
// Return a pointer to a copy of this rule.
virtual Rule* Copy() const = 0;
// If this is a base+offset rule, change its base register to REG.
// Otherwise, do nothing. (Ugly, but required for DW_CFA_def_cfa_register.)
virtual void SetBaseRegister(unsigned reg) { }
// If this is a base+offset rule, change its offset to OFFSET. Otherwise,
// do nothing. (Ugly, but required for DW_CFA_def_cfa_offset.)
virtual void SetOffset(long long offset) { }
};
// Rule: the value the register had in the caller cannot be recovered.
class CallFrameInfo::UndefinedRule: public CallFrameInfo::Rule {
public:
UndefinedRule() { }
~UndefinedRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->UndefinedRule(address, reg);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const UndefinedRule* our_rhs = dynamic_cast<const UndefinedRule*>(&rhs);
return (our_rhs != NULL);
}
Rule* Copy() const { return new UndefinedRule(*this); }
};
// Rule: the register's value is the same as that it had in the caller.
class CallFrameInfo::SameValueRule: public CallFrameInfo::Rule {
public:
SameValueRule() { }
~SameValueRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->SameValueRule(address, reg);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const SameValueRule* our_rhs = dynamic_cast<const SameValueRule*>(&rhs);
return (our_rhs != NULL);
}
Rule* Copy() const { return new SameValueRule(*this); }
};
// Rule: the register is saved at OFFSET from BASE_REGISTER. BASE_REGISTER
// may be CallFrameInfo::Handler::kCFARegister.
class CallFrameInfo::OffsetRule: public CallFrameInfo::Rule {
public:
OffsetRule(int base_register, long offset)
: base_register_(base_register), offset_(offset) { }
~OffsetRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->OffsetRule(address, reg, base_register_, offset_);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const OffsetRule* our_rhs = dynamic_cast<const OffsetRule*>(&rhs);
return (our_rhs &&
base_register_ == our_rhs->base_register_ &&
offset_ == our_rhs->offset_);
}
Rule* Copy() const { return new OffsetRule(*this); }
// We don't actually need SetBaseRegister or SetOffset here, since they
// are only ever applied to CFA rules, for DW_CFA_def_cfa_offset, and it
// doesn't make sense to use OffsetRule for computing the CFA: it
// computes the address at which a register is saved, not a value.
private:
int base_register_;
long offset_;
};
// Rule: the value the register had in the caller is the value of
// BASE_REGISTER plus offset. BASE_REGISTER may be
// CallFrameInfo::Handler::kCFARegister.
class CallFrameInfo::ValOffsetRule: public CallFrameInfo::Rule {
public:
ValOffsetRule(int base_register, long offset)
: base_register_(base_register), offset_(offset) { }
~ValOffsetRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->ValOffsetRule(address, reg, base_register_, offset_);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const ValOffsetRule* our_rhs = dynamic_cast<const ValOffsetRule*>(&rhs);
return (our_rhs &&
base_register_ == our_rhs->base_register_ &&
offset_ == our_rhs->offset_);
}
Rule* Copy() const { return new ValOffsetRule(*this); }
void SetBaseRegister(unsigned reg) { base_register_ = reg; }
void SetOffset(long long offset) { offset_ = offset; }
private:
int base_register_;
long offset_;
};
// Rule: the register has been saved in another register REGISTER_NUMBER_.
class CallFrameInfo::RegisterRule: public CallFrameInfo::Rule {
public:
explicit RegisterRule(int register_number)
: register_number_(register_number) { }
~RegisterRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->RegisterRule(address, reg, register_number_);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const RegisterRule* our_rhs = dynamic_cast<const RegisterRule*>(&rhs);
return (our_rhs && register_number_ == our_rhs->register_number_);
}
Rule* Copy() const { return new RegisterRule(*this); }
private:
int register_number_;
};
// Rule: EXPRESSION evaluates to the address at which the register is saved.
class CallFrameInfo::ExpressionRule: public CallFrameInfo::Rule {
public:
explicit ExpressionRule(const string& expression)
: expression_(expression) { }
~ExpressionRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->ExpressionRule(address, reg, expression_);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const ExpressionRule* our_rhs = dynamic_cast<const ExpressionRule*>(&rhs);
return (our_rhs && expression_ == our_rhs->expression_);
}
Rule* Copy() const { return new ExpressionRule(*this); }
private:
string expression_;
};
// Rule: EXPRESSION evaluates to the address at which the register is saved.
class CallFrameInfo::ValExpressionRule: public CallFrameInfo::Rule {
public:
explicit ValExpressionRule(const string& expression)
: expression_(expression) { }
~ValExpressionRule() { }
bool Handle(Handler* handler, uint64_t address, int reg) const {
return handler->ValExpressionRule(address, reg, expression_);
}
bool operator==(const Rule& rhs) const {
// dynamic_cast is allowed by the Google C++ Style Guide, if the use has
// been carefully considered; cheap RTTI-like workarounds are forbidden.
const ValExpressionRule* our_rhs =
dynamic_cast<const ValExpressionRule*>(&rhs);
return (our_rhs && expression_ == our_rhs->expression_);
}
Rule* Copy() const { return new ValExpressionRule(*this); }
private:
string expression_;
};
// A map from register numbers to rules.
class CallFrameInfo::RuleMap {
public:
RuleMap() : cfa_rule_(NULL) { }
RuleMap(const RuleMap& rhs) : cfa_rule_(NULL) { *this = rhs; }
~RuleMap() { Clear(); }
RuleMap& operator=(const RuleMap& rhs);
// Set the rule for computing the CFA to RULE. Take ownership of RULE.
void SetCFARule(Rule* rule) { delete cfa_rule_; cfa_rule_ = rule; }
// Return the current CFA rule. Unlike RegisterRule, this RuleMap retains
// ownership of the rule. We use this for DW_CFA_def_cfa_offset and
// DW_CFA_def_cfa_register, and for detecting references to the CFA before
// a rule for it has been established.
Rule* CFARule() const { return cfa_rule_; }
// Return the rule for REG, or NULL if there is none. The caller takes
// ownership of the result.
Rule* RegisterRule(int reg) const;
// Set the rule for computing REG to RULE. Take ownership of RULE.
void SetRegisterRule(int reg, Rule* rule);
// Make all the appropriate calls to HANDLER as if we were changing from
// this RuleMap to NEW_RULES at ADDRESS. We use this to implement
// DW_CFA_restore_state, where lots of rules can change simultaneously.
// Return true if all handlers returned true; otherwise, return false.
bool HandleTransitionTo(Handler* handler, uint64_t address,
const RuleMap& new_rules) const;
private:
// A map from register numbers to Rules.
typedef std::map<int, Rule*> RuleByNumber;
// Remove all register rules and clear cfa_rule_.
void Clear();
// The rule for computing the canonical frame address. This RuleMap owns
// this rule.
Rule* cfa_rule_;
// A map from register numbers to postfix expressions to recover
// their values. This RuleMap owns the Rules the map refers to.
RuleByNumber registers_;
};
CallFrameInfo::RuleMap& CallFrameInfo::RuleMap::operator=(const RuleMap& rhs) {
Clear();
// Since each map owns the rules it refers to, assignment must copy them.
if (rhs.cfa_rule_) cfa_rule_ = rhs.cfa_rule_->Copy();
for (RuleByNumber::const_iterator it = rhs.registers_.begin();
it != rhs.registers_.end(); it++)
registers_[it->first] = it->second->Copy();
return *this;
}
CallFrameInfo::Rule* CallFrameInfo::RuleMap::RegisterRule(int reg) const {
assert(reg != Handler::kCFARegister);
RuleByNumber::const_iterator it = registers_.find(reg);
if (it != registers_.end())
return it->second->Copy();
else
return NULL;
}
void CallFrameInfo::RuleMap::SetRegisterRule(int reg, Rule* rule) {
assert(reg != Handler::kCFARegister);
assert(rule);
Rule** slot = &registers_[reg];
delete *slot;
*slot = rule;
}
bool CallFrameInfo::RuleMap::HandleTransitionTo(
Handler* handler,
uint64_t address,
const RuleMap& new_rules) const {
// Transition from cfa_rule_ to new_rules.cfa_rule_.
if (cfa_rule_ && new_rules.cfa_rule_) {
if (*cfa_rule_ != *new_rules.cfa_rule_ &&
!new_rules.cfa_rule_->Handle(handler, address,
Handler::kCFARegister))
return false;
} else if (cfa_rule_) {
// this RuleMap has a CFA rule but new_rules doesn't.
// CallFrameInfo::Handler has no way to handle this --- and shouldn't;
// it's garbage input. The instruction interpreter should have
// detected this and warned, so take no action here.
} else if (new_rules.cfa_rule_) {
// This shouldn't be possible: NEW_RULES is some prior state, and
// there's no way to remove entries.
assert(0);
} else {
// Both CFA rules are empty. No action needed.
}
// Traverse the two maps in order by register number, and report
// whatever differences we find.
RuleByNumber::const_iterator old_it = registers_.begin();
RuleByNumber::const_iterator new_it = new_rules.registers_.begin();
while (old_it != registers_.end() && new_it != new_rules.registers_.end()) {
if (old_it->first < new_it->first) {
// This RuleMap has an entry for old_it->first, but NEW_RULES
// doesn't.
//
// This isn't really the right thing to do, but since CFI generally
// only mentions callee-saves registers, and GCC's convention for
// callee-saves registers is that they are unchanged, it's a good
// approximation.
if (!handler->SameValueRule(address, old_it->first))
return false;
old_it++;
} else if (old_it->first > new_it->first) {
// NEW_RULES has entry for new_it->first, but this RuleMap
// doesn't. This shouldn't be possible: NEW_RULES is some prior
// state, and there's no way to remove entries.
assert(0);
} else {
// Both maps have an entry for this register. Report the new
// rule if it is different.
if (*old_it->second != *new_it->second &&
!new_it->second->Handle(handler, address, new_it->first))
return false;
new_it++, old_it++;
}
}
// Finish off entries from this RuleMap with no counterparts in new_rules.
while (old_it != registers_.end()) {
if (!handler->SameValueRule(address, old_it->first))
return false;
old_it++;
}
// Since we only make transitions from a rule set to some previously
// saved rule set, and we can only add rules to the map, NEW_RULES
// must have fewer rules than *this.
assert(new_it == new_rules.registers_.end());
return true;
}
// Remove all register rules and clear cfa_rule_.
void CallFrameInfo::RuleMap::Clear() {
delete cfa_rule_;
cfa_rule_ = NULL;
for (RuleByNumber::iterator it = registers_.begin();
it != registers_.end(); it++)
delete it->second;
registers_.clear();
}
// The state of the call frame information interpreter as it processes
// instructions from a CIE and FDE.
class CallFrameInfo::State {
public:
// Create a call frame information interpreter state with the given
// reporter, reader, handler, and initial call frame info address.
State(ByteReader* reader, Handler* handler, Reporter* reporter,
uint64_t address)
: reader_(reader), handler_(handler), reporter_(reporter),
address_(address), entry_(NULL), cursor_(NULL) { }
// Interpret instructions from CIE, save the resulting rule set for
// DW_CFA_restore instructions, and return true. On error, report
// the problem to reporter_ and return false.
bool InterpretCIE(const CIE& cie);
// Interpret instructions from FDE, and return true. On error,
// report the problem to reporter_ and return false.
bool InterpretFDE(const FDE& fde);
private:
// The operands of a CFI instruction, for ParseOperands.
struct Operands {
unsigned register_number; // A register number.
uint64_t offset; // An offset or address.
long signed_offset; // A signed offset.
string expression; // A DWARF expression.
};
// Parse CFI instruction operands from STATE's instruction stream as
// described by FORMAT. On success, populate OPERANDS with the
// results, and return true. On failure, report the problem and
// return false.
//
// Each character of FORMAT should be one of the following:
//
// 'r' unsigned LEB128 register number (OPERANDS->register_number)
// 'o' unsigned LEB128 offset (OPERANDS->offset)
// 's' signed LEB128 offset (OPERANDS->signed_offset)
// 'a' machine-size address (OPERANDS->offset)
// (If the CIE has a 'z' augmentation string, 'a' uses the
// encoding specified by the 'R' argument.)
// '1' a one-byte offset (OPERANDS->offset)
// '2' a two-byte offset (OPERANDS->offset)
// '4' a four-byte offset (OPERANDS->offset)
// '8' an eight-byte offset (OPERANDS->offset)
// 'e' a DW_FORM_block holding a (OPERANDS->expression)
// DWARF expression
bool ParseOperands(const char* format, Operands* operands);
// Interpret one CFI instruction from STATE's instruction stream, update
// STATE, report any rule changes to handler_, and return true. On
// failure, report the problem and return false.
bool DoInstruction();
// The following Do* member functions are subroutines of DoInstruction,
// factoring out the actual work of operations that have several
// different encodings.
// Set the CFA rule to be the value of BASE_REGISTER plus OFFSET, and
// return true. On failure, report and return false. (Used for
// DW_CFA_def_cfa and DW_CFA_def_cfa_sf.)
bool DoDefCFA(unsigned base_register, long offset);
// Change the offset of the CFA rule to OFFSET, and return true. On
// failure, report and return false. (Subroutine for
// DW_CFA_def_cfa_offset and DW_CFA_def_cfa_offset_sf.)
bool DoDefCFAOffset(long offset);
// Specify that REG can be recovered using RULE, and return true. On
// failure, report and return false.
bool DoRule(unsigned reg, Rule* rule);
// Specify that REG can be found at OFFSET from the CFA, and return true.
// On failure, report and return false. (Subroutine for DW_CFA_offset,
// DW_CFA_offset_extended, and DW_CFA_offset_extended_sf.)
bool DoOffset(unsigned reg, long offset);
// Specify that the caller's value for REG is the CFA plus OFFSET,
// and return true. On failure, report and return false. (Subroutine
// for DW_CFA_val_offset and DW_CFA_val_offset_sf.)
bool DoValOffset(unsigned reg, long offset);
// Restore REG to the rule established in the CIE, and return true. On
// failure, report and return false. (Subroutine for DW_CFA_restore and
// DW_CFA_restore_extended.)
bool DoRestore(unsigned reg);
// Return the section offset of the instruction at cursor. For use
// in error messages.
uint64_t CursorOffset() { return entry_->offset + (cursor_ - entry_->start); }
// Report that entry_ is incomplete, and return false. For brevity.
bool ReportIncomplete() {
reporter_->Incomplete(entry_->offset, entry_->kind);
return false;
}
// For reading multi-byte values with the appropriate endianness.
ByteReader* reader_;
// The handler to which we should report the data we find.
Handler* handler_;
// For reporting problems in the info we're parsing.
Reporter* reporter_;
// The code address to which the next instruction in the stream applies.
uint64_t address_;
// The entry whose instructions we are currently processing. This is
// first a CIE, and then an FDE.
const Entry* entry_;
// The next instruction to process.
const uint8_t* cursor_;
// The current set of rules.
RuleMap rules_;
// The set of rules established by the CIE, used by DW_CFA_restore
// and DW_CFA_restore_extended. We set this after interpreting the
// CIE's instructions.
RuleMap cie_rules_;
// A stack of saved states, for DW_CFA_remember_state and
// DW_CFA_restore_state.
std::stack<RuleMap> saved_rules_;
};
bool CallFrameInfo::State::InterpretCIE(const CIE& cie) {
entry_ = &cie;
cursor_ = entry_->instructions;
while (cursor_ < entry_->end)
if (!DoInstruction())
return false;
// Note the rules established by the CIE, for use by DW_CFA_restore
// and DW_CFA_restore_extended.
cie_rules_ = rules_;
return true;
}
bool CallFrameInfo::State::InterpretFDE(const FDE& fde) {
entry_ = &fde;
cursor_ = entry_->instructions;
while (cursor_ < entry_->end)
if (!DoInstruction())
return false;
return true;
}
bool CallFrameInfo::State::ParseOperands(const char* format,
Operands* operands) {
size_t len;
const char* operand;
for (operand = format; *operand; operand++) {
size_t bytes_left = entry_->end - cursor_;
switch (*operand) {
case 'r':
operands->register_number = reader_->ReadUnsignedLEB128(cursor_, &len);
if (len > bytes_left) return ReportIncomplete();
cursor_ += len;
break;
case 'o':
operands->offset = reader_->ReadUnsignedLEB128(cursor_, &len);
if (len > bytes_left) return ReportIncomplete();
cursor_ += len;
break;
case 's':
operands->signed_offset = reader_->ReadSignedLEB128(cursor_, &len);
if (len > bytes_left) return ReportIncomplete();
cursor_ += len;
break;
case 'a':
operands->offset =
reader_->ReadEncodedPointer(cursor_, entry_->cie->pointer_encoding,
&len);
if (len > bytes_left) return ReportIncomplete();
cursor_ += len;
break;
case '1':
if (1 > bytes_left) return ReportIncomplete();
operands->offset = static_cast<unsigned char>(*cursor_++);
break;
case '2':
if (2 > bytes_left) return ReportIncomplete();
operands->offset = reader_->ReadTwoBytes(cursor_);
cursor_ += 2;
break;
case '4':
if (4 > bytes_left) return ReportIncomplete();
operands->offset = reader_->ReadFourBytes(cursor_);
cursor_ += 4;
break;
case '8':
if (8 > bytes_left) return ReportIncomplete();
operands->offset = reader_->ReadEightBytes(cursor_);
cursor_ += 8;
break;
case 'e': {
size_t expression_length = reader_->ReadUnsignedLEB128(cursor_, &len);
if (len > bytes_left || expression_length > bytes_left - len)
return ReportIncomplete();
cursor_ += len;
operands->expression = string(reinterpret_cast<const char*>(cursor_),
expression_length);
cursor_ += expression_length;
break;
}
default:
assert(0);
}
}
return true;
}
bool CallFrameInfo::State::DoInstruction() {
CIE* cie = entry_->cie;
Operands ops;
// Our entry's kind should have been set by now.
assert(entry_->kind != kUnknown);
// We shouldn't have been invoked unless there were more
// instructions to parse.
assert(cursor_ < entry_->end);
unsigned opcode = *cursor_++;
if ((opcode & 0xc0) != 0) {
switch (opcode & 0xc0) {
// Advance the address.
case DW_CFA_advance_loc: {
size_t code_offset = opcode & 0x3f;
address_ += code_offset * cie->code_alignment_factor;
break;
}
// Find a register at an offset from the CFA.
case DW_CFA_offset:
if (!ParseOperands("o", &ops) ||
!DoOffset(opcode & 0x3f, ops.offset * cie->data_alignment_factor))
return false;
break;
// Restore the rule established for a register by the CIE.
case DW_CFA_restore:
if (!DoRestore(opcode & 0x3f)) return false;
break;
// The 'if' above should have excluded this possibility.
default:
assert(0);
}
// Return here, so the big switch below won't be indented.
return true;
}
switch (opcode) {
// Set the address.
case DW_CFA_set_loc:
if (!ParseOperands("a", &ops)) return false;
address_ = ops.offset;
break;
// Advance the address.
case DW_CFA_advance_loc1:
if (!ParseOperands("1", &ops)) return false;
address_ += ops.offset * cie->code_alignment_factor;
break;
// Advance the address.
case DW_CFA_advance_loc2:
if (!ParseOperands("2", &ops)) return false;
address_ += ops.offset * cie->code_alignment_factor;
break;
// Advance the address.
case DW_CFA_advance_loc4:
if (!ParseOperands("4", &ops)) return false;
address_ += ops.offset * cie->code_alignment_factor;
break;
// Advance the address.
case DW_CFA_MIPS_advance_loc8:
if (!ParseOperands("8", &ops)) return false;
address_ += ops.offset * cie->code_alignment_factor;
break;
// Compute the CFA by adding an offset to a register.
case DW_CFA_def_cfa:
if (!ParseOperands("ro", &ops) ||
!DoDefCFA(ops.register_number, ops.offset))
return false;
break;
// Compute the CFA by adding an offset to a register.
case DW_CFA_def_cfa_sf:
if (!ParseOperands("rs", &ops) ||
!DoDefCFA(ops.register_number,
ops.signed_offset * cie->data_alignment_factor))
return false;
break;
// Change the base register used to compute the CFA.
case DW_CFA_def_cfa_register: {
if (!ParseOperands("r", &ops)) return false;
Rule* cfa_rule = rules_.CFARule();
if (!cfa_rule) {
if (!DoDefCFA(ops.register_number, ops.offset)) {
reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset());
return false;
}
} else {
cfa_rule->SetBaseRegister(ops.register_number);
if (!cfa_rule->Handle(handler_, address_,
Handler::kCFARegister))
return false;
}
break;
}
// Change the offset used to compute the CFA.
case DW_CFA_def_cfa_offset:
if (!ParseOperands("o", &ops) ||
!DoDefCFAOffset(ops.offset))
return false;
break;
// Change the offset used to compute the CFA.
case DW_CFA_def_cfa_offset_sf:
if (!ParseOperands("s", &ops) ||
!DoDefCFAOffset(ops.signed_offset * cie->data_alignment_factor))
return false;
break;
// Specify an expression whose value is the CFA.
case DW_CFA_def_cfa_expression: {
if (!ParseOperands("e", &ops))
return false;
Rule* rule = new ValExpressionRule(ops.expression);
rules_.SetCFARule(rule);
if (!rule->Handle(handler_, address_,
Handler::kCFARegister))
return false;
break;
}
// The register's value cannot be recovered.
case DW_CFA_undefined: {
if (!ParseOperands("r", &ops) ||
!DoRule(ops.register_number, new UndefinedRule()))
return false;
break;
}
// The register's value is unchanged from its value in the caller.
case DW_CFA_same_value: {
if (!ParseOperands("r", &ops) ||
!DoRule(ops.register_number, new SameValueRule()))
return false;
break;
}
// Find a register at an offset from the CFA.
case DW_CFA_offset_extended:
if (!ParseOperands("ro", &ops) ||
!DoOffset(ops.register_number,
ops.offset * cie->data_alignment_factor))
return false;
break;
// The register is saved at an offset from the CFA.
case DW_CFA_offset_extended_sf:
if (!ParseOperands("rs", &ops) ||
!DoOffset(ops.register_number,
ops.signed_offset * cie->data_alignment_factor))
return false;
break;
// The register is saved at an offset from the CFA.
case DW_CFA_GNU_negative_offset_extended:
if (!ParseOperands("ro", &ops) ||
!DoOffset(ops.register_number,
-ops.offset * cie->data_alignment_factor))
return false;
break;
// The register's value is the sum of the CFA plus an offset.
case DW_CFA_val_offset:
if (!ParseOperands("ro", &ops) ||
!DoValOffset(ops.register_number,
ops.offset * cie->data_alignment_factor))
return false;
break;
// The register's value is the sum of the CFA plus an offset.
case DW_CFA_val_offset_sf:
if (!ParseOperands("rs", &ops) ||
!DoValOffset(ops.register_number,
ops.signed_offset * cie->data_alignment_factor))
return false;
break;
// The register has been saved in another register.
case DW_CFA_register: {
if (!ParseOperands("ro", &ops) ||
!DoRule(ops.register_number, new RegisterRule(ops.offset)))
return false;
break;
}
// An expression yields the address at which the register is saved.
case DW_CFA_expression: {
if (!ParseOperands("re", &ops) ||
!DoRule(ops.register_number, new ExpressionRule(ops.expression)))
return false;
break;
}
// An expression yields the caller's value for the register.
case DW_CFA_val_expression: {
if (!ParseOperands("re", &ops) ||
!DoRule(ops.register_number, new ValExpressionRule(ops.expression)))
return false;
break;
}
// Restore the rule established for a register by the CIE.
case DW_CFA_restore_extended:
if (!ParseOperands("r", &ops) ||
!DoRestore( ops.register_number))
return false;
break;
// Save the current set of rules on a stack.
case DW_CFA_remember_state:
saved_rules_.push(rules_);
break;
// Pop the current set of rules off the stack.
case DW_CFA_restore_state: {
if (saved_rules_.empty()) {
reporter_->EmptyStateStack(entry_->offset, entry_->kind,
CursorOffset());
return false;
}
const RuleMap& new_rules = saved_rules_.top();
if (rules_.CFARule() && !new_rules.CFARule()) {
reporter_->ClearingCFARule(entry_->offset, entry_->kind,
CursorOffset());
return false;
}
rules_.HandleTransitionTo(handler_, address_, new_rules);
rules_ = new_rules;
saved_rules_.pop();
break;
}
// No operation. (Padding instruction.)
case DW_CFA_nop:
break;
// A SPARC register window save: Registers 8 through 15 (%o0-%o7)
// are saved in registers 24 through 31 (%i0-%i7), and registers
// 16 through 31 (%l0-%l7 and %i0-%i7) are saved at CFA offsets
// (0-15 * the register size). The register numbers must be
// hard-coded. A GNU extension, and not a pretty one.
case DW_CFA_GNU_window_save: {
// Save %o0-%o7 in %i0-%i7.
for (int i = 8; i < 16; i++)
if (!DoRule(i, new RegisterRule(i + 16)))
return false;
// Save %l0-%l7 and %i0-%i7 at the CFA.
for (int i = 16; i < 32; i++)
// Assume that the byte reader's address size is the same as
// the architecture's register size. !@#%*^ hilarious.
if (!DoRule(i, new OffsetRule(Handler::kCFARegister,
(i - 16) * reader_->AddressSize())))
return false;
break;
}
// I'm not sure what this is. GDB doesn't use it for unwinding.
case DW_CFA_GNU_args_size:
if (!ParseOperands("o", &ops)) return false;
break;
// An opcode we don't recognize.
default: {
reporter_->BadInstruction(entry_->offset, entry_->kind, CursorOffset());
return false;
}
}
return true;
}
bool CallFrameInfo::State::DoDefCFA(unsigned base_register, long offset) {
Rule* rule = new ValOffsetRule(base_register, offset);
rules_.SetCFARule(rule);
return rule->Handle(handler_, address_,
Handler::kCFARegister);
}
bool CallFrameInfo::State::DoDefCFAOffset(long offset) {
Rule* cfa_rule = rules_.CFARule();
if (!cfa_rule) {
reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset());
return false;
}
cfa_rule->SetOffset(offset);
return cfa_rule->Handle(handler_, address_,
Handler::kCFARegister);
}
bool CallFrameInfo::State::DoRule(unsigned reg, Rule* rule) {
rules_.SetRegisterRule(reg, rule);
return rule->Handle(handler_, address_, reg);
}
bool CallFrameInfo::State::DoOffset(unsigned reg, long offset) {
if (!rules_.CFARule()) {
reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset());
return false;
}
return DoRule(reg,
new OffsetRule(Handler::kCFARegister, offset));
}
bool CallFrameInfo::State::DoValOffset(unsigned reg, long offset) {
if (!rules_.CFARule()) {
reporter_->NoCFARule(entry_->offset, entry_->kind, CursorOffset());
return false;
}
return DoRule(reg,
new ValOffsetRule(Handler::kCFARegister, offset));
}
bool CallFrameInfo::State::DoRestore(unsigned reg) {
// DW_CFA_restore and DW_CFA_restore_extended don't make sense in a CIE.
if (entry_->kind == kCIE) {
reporter_->RestoreInCIE(entry_->offset, CursorOffset());
return false;
}
Rule* rule = cie_rules_.RegisterRule(reg);
if (!rule) {
// This isn't really the right thing to do, but since CFI generally
// only mentions callee-saves registers, and GCC's convention for
// callee-saves registers is that they are unchanged, it's a good
// approximation.
rule = new SameValueRule();
}
return DoRule(reg, rule);
}
bool CallFrameInfo::ReadEntryPrologue(const uint8_t* cursor, Entry* entry) {
const uint8_t* buffer_end = buffer_ + buffer_length_;
// Initialize enough of ENTRY for use in error reporting.
entry->offset = cursor - buffer_;
entry->start = cursor;
entry->kind = kUnknown;
entry->end = NULL;
// Read the initial length. This sets reader_'s offset size.
size_t length_size;
uint64_t length = reader_->ReadInitialLength(cursor, &length_size);
if (length_size > size_t(buffer_end - cursor))
return ReportIncomplete(entry);
cursor += length_size;
// In a .eh_frame section, a length of zero marks the end of the series
// of entries.
if (length == 0 && eh_frame_) {
entry->kind = kTerminator;
entry->end = cursor;
return true;
}
// Validate the length.
if (length > size_t(buffer_end - cursor))
return ReportIncomplete(entry);
// The length is the number of bytes after the initial length field;
// we have that position handy at this point, so compute the end
// now. (If we're parsing 64-bit-offset DWARF on a 32-bit machine,
// and the length didn't fit in a size_t, we would have rejected it
// above.)
entry->end = cursor + length;
// Parse the next field: either the offset of a CIE or a CIE id.
size_t offset_size = reader_->OffsetSize();
if (offset_size > size_t(entry->end - cursor)) return ReportIncomplete(entry);
entry->id = reader_->ReadOffset(cursor);
// Don't advance cursor past id field yet; in .eh_frame data we need
// the id's position to compute the section offset of an FDE's CIE.
// Now we can decide what kind of entry this is.
if (eh_frame_) {
// In .eh_frame data, an ID of zero marks the entry as a CIE, and
// anything else is an offset from the id field of the FDE to the start
// of the CIE.
if (entry->id == 0) {
entry->kind = kCIE;
} else {
entry->kind = kFDE;
// Turn the offset from the id into an offset from the buffer's start.
entry->id = (cursor - buffer_) - entry->id;
}
} else {
// In DWARF CFI data, an ID of ~0 (of the appropriate width, given the
// offset size for the entry) marks the entry as a CIE, and anything
// else is the offset of the CIE from the beginning of the section.
if (offset_size == 4)
entry->kind = (entry->id == 0xffffffff) ? kCIE : kFDE;
else {
assert(offset_size == 8);
entry->kind = (entry->id == 0xffffffffffffffffULL) ? kCIE : kFDE;
}
}
// Now advance cursor past the id.
cursor += offset_size;
// The fields specific to this kind of entry start here.
entry->fields = cursor;
entry->cie = NULL;
return true;
}
bool CallFrameInfo::ReadCIEFields(CIE* cie) {
const uint8_t* cursor = cie->fields;
size_t len;
assert(cie->kind == kCIE);
// Prepare for early exit.
cie->version = 0;
cie->augmentation.clear();
cie->code_alignment_factor = 0;
cie->data_alignment_factor = 0;
cie->return_address_register = 0;
cie->has_z_augmentation = false;
cie->pointer_encoding = DW_EH_PE_absptr;
cie->instructions = 0;
// Parse the version number.
if (cie->end - cursor < 1)
return ReportIncomplete(cie);
cie->version = reader_->ReadOneByte(cursor);
cursor++;
// If we don't recognize the version, we can't parse any more fields of the
// CIE. For DWARF CFI, we handle versions 1 through 4 (there was never a
// version 2 of CFI data). For .eh_frame, we handle versions 1 and 4 as well;
// the difference between those versions seems to be the same as for
// .debug_frame.
if (cie->version < 1 || cie->version > 4) {
reporter_->UnrecognizedVersion(cie->offset, cie->version);
return false;
}
const uint8_t* augmentation_start = cursor;
const uint8_t* augmentation_end =
reinterpret_cast<const uint8_t*>(memchr(augmentation_start, '\0',
cie->end - augmentation_start));
if (! augmentation_end) return ReportIncomplete(cie);
cursor = augmentation_end;
cie->augmentation = string(reinterpret_cast<const char*>(augmentation_start),
cursor - augmentation_start);
// Skip the terminating '\0'.
cursor++;
// Is this CFI augmented?
if (!cie->augmentation.empty()) {
// Is it an augmentation we recognize?
if (cie->augmentation[0] == DW_Z_augmentation_start) {
// Linux C++ ABI 'z' augmentation, used for exception handling data.
cie->has_z_augmentation = true;
} else {
// Not an augmentation we recognize. Augmentations can have arbitrary
// effects on the form of rest of the content, so we have to give up.
reporter_->UnrecognizedAugmentation(cie->offset, cie->augmentation);
return false;
}
}
if (cie->version >= 4) {
cie->address_size = *cursor++;
if (cie->address_size != 8 && cie->address_size != 4) {
reporter_->UnexpectedAddressSize(cie->offset, cie->address_size);
return false;
}
cie->segment_size = *cursor++;
if (cie->segment_size != 0) {
reporter_->UnexpectedSegmentSize(cie->offset, cie->segment_size);
return false;
}
}
// Parse the code alignment factor.
cie->code_alignment_factor = reader_->ReadUnsignedLEB128(cursor, &len);
if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie);
cursor += len;
// Parse the data alignment factor.
cie->data_alignment_factor = reader_->ReadSignedLEB128(cursor, &len);
if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie);
cursor += len;
// Parse the return address register. This is a ubyte in version 1, and
// a ULEB128 in version 3.
if (cie->version == 1) {
if (cursor >= cie->end) return ReportIncomplete(cie);
cie->return_address_register = uint8_t(*cursor++);
} else {
cie->return_address_register = reader_->ReadUnsignedLEB128(cursor, &len);
if (size_t(cie->end - cursor) < len) return ReportIncomplete(cie);
cursor += len;
}
// If we have a 'z' augmentation string, find the augmentation data and
// use the augmentation string to parse it.
if (cie->has_z_augmentation) {
uint64_t data_size = reader_->ReadUnsignedLEB128(cursor, &len);
if (size_t(cie->end - cursor) < len + data_size)
return ReportIncomplete(cie);
cursor += len;
const uint8_t* data = cursor;
cursor += data_size;
const uint8_t* data_end = cursor;
cie->has_z_lsda = false;
cie->has_z_personality = false;
cie->has_z_signal_frame = false;
// Walk the augmentation string, and extract values from the
// augmentation data as the string directs.
for (size_t i = 1; i < cie->augmentation.size(); i++) {
switch (cie->augmentation[i]) {
case DW_Z_has_LSDA:
// The CIE's augmentation data holds the language-specific data
// area pointer's encoding, and the FDE's augmentation data holds
// the pointer itself.
cie->has_z_lsda = true;
// Fetch the LSDA encoding from the augmentation data.
if (data >= data_end) return ReportIncomplete(cie);
cie->lsda_encoding = DwarfPointerEncoding(*data++);
if (!reader_->ValidEncoding(cie->lsda_encoding)) {
reporter_->InvalidPointerEncoding(cie->offset, cie->lsda_encoding);
return false;
}
// Don't check if the encoding is usable here --- we haven't
// read the FDE's fields yet, so we're not prepared for
// DW_EH_PE_funcrel, although that's a fine encoding for the
// LSDA to use, since it appears in the FDE.
break;
case DW_Z_has_personality_routine:
// The CIE's augmentation data holds the personality routine
// pointer's encoding, followed by the pointer itself.
cie->has_z_personality = true;
// Fetch the personality routine pointer's encoding from the
// augmentation data.
if (data >= data_end) return ReportIncomplete(cie);
cie->personality_encoding = DwarfPointerEncoding(*data++);
if (!reader_->ValidEncoding(cie->personality_encoding)) {
reporter_->InvalidPointerEncoding(cie->offset,
cie->personality_encoding);
return false;
}
if (!reader_->UsableEncoding(cie->personality_encoding)) {
reporter_->UnusablePointerEncoding(cie->offset,
cie->personality_encoding);
return false;
}
// Fetch the personality routine's pointer itself from the data.
cie->personality_address =
reader_->ReadEncodedPointer(data, cie->personality_encoding,
&len);
if (len > size_t(data_end - data))
return ReportIncomplete(cie);
data += len;
break;
case DW_Z_has_FDE_address_encoding:
// The CIE's augmentation data holds the pointer encoding to use
// for addresses in the FDE.
if (data >= data_end) return ReportIncomplete(cie);
cie->pointer_encoding = DwarfPointerEncoding(*data++);
if (!reader_->ValidEncoding(cie->pointer_encoding)) {
reporter_->InvalidPointerEncoding(cie->offset,
cie->pointer_encoding);
return false;
}
if (!reader_->UsableEncoding(cie->pointer_encoding)) {
reporter_->UnusablePointerEncoding(cie->offset,
cie->pointer_encoding);
return false;
}
break;
case DW_Z_is_signal_trampoline:
// Frames using this CIE are signal delivery frames.
cie->has_z_signal_frame = true;
break;
default:
// An augmentation we don't recognize.
reporter_->UnrecognizedAugmentation(cie->offset, cie->augmentation);
return false;
}
}
}
// The CIE's instructions start here.
cie->instructions = cursor;
return true;
}
bool CallFrameInfo::ReadFDEFields(FDE* fde) {
const uint8_t* cursor = fde->fields;
size_t size;
fde->address = reader_->ReadEncodedPointer(cursor, fde->cie->pointer_encoding,
&size);
if (size > size_t(fde->end - cursor))
return ReportIncomplete(fde);
cursor += size;
reader_->SetFunctionBase(fde->address);
// For the length, we strip off the upper nybble of the encoding used for
// the starting address.
DwarfPointerEncoding length_encoding =
DwarfPointerEncoding(fde->cie->pointer_encoding & 0x0f);
fde->size = reader_->ReadEncodedPointer(cursor, length_encoding, &size);
if (size > size_t(fde->end - cursor))
return ReportIncomplete(fde);
cursor += size;
// If the CIE has a 'z' augmentation string, then augmentation data
// appears here.
if (fde->cie->has_z_augmentation) {
uint64_t data_size = reader_->ReadUnsignedLEB128(cursor, &size);
if (size_t(fde->end - cursor) < size + data_size)
return ReportIncomplete(fde);
cursor += size;
// In the abstract, we should walk the augmentation string, and extract
// items from the FDE's augmentation data as we encounter augmentation
// string characters that specify their presence: the ordering of items
// in the augmentation string determines the arrangement of values in
// the augmentation data.
//
// In practice, there's only ever one value in FDE augmentation data
// that we support --- the LSDA pointer --- and we have to bail if we
// see any unrecognized augmentation string characters. So if there is
// anything here at all, we know what it is, and where it starts.
if (fde->cie->has_z_lsda) {
// Check whether the LSDA's pointer encoding is usable now: only once
// we've parsed the FDE's starting address do we call reader_->
// SetFunctionBase, so that the DW_EH_PE_funcrel encoding becomes
// usable.
if (!reader_->UsableEncoding(fde->cie->lsda_encoding)) {
reporter_->UnusablePointerEncoding(fde->cie->offset,
fde->cie->lsda_encoding);
return false;
}
fde->lsda_address =
reader_->ReadEncodedPointer(cursor, fde->cie->lsda_encoding, &size);
if (size > data_size)
return ReportIncomplete(fde);
// Ideally, we would also complain here if there were unconsumed
// augmentation data.
}
cursor += data_size;
}
// The FDE's instructions start after those.
fde->instructions = cursor;
return true;
}
bool CallFrameInfo::Start() {
const uint8_t* buffer_end = buffer_ + buffer_length_;
const uint8_t* cursor;
bool all_ok = true;
const uint8_t* entry_end;
bool ok;
// Traverse all the entries in buffer_, skipping CIEs and offering
// FDEs to the handler.
for (cursor = buffer_; cursor < buffer_end;
cursor = entry_end, all_ok = all_ok && ok) {
FDE fde;
// Make it easy to skip this entry with 'continue': assume that
// things are not okay until we've checked all the data, and
// prepare the address of the next entry.
ok = false;
// Read the entry's prologue.
if (!ReadEntryPrologue(cursor, &fde)) {
if (!fde.end) {
// If we couldn't even figure out this entry's extent, then we
// must stop processing entries altogether.
all_ok = false;
break;
}
entry_end = fde.end;
continue;
}
// The next iteration picks up after this entry.
entry_end = fde.end;
// Did we see an .eh_frame terminating mark?
if (fde.kind == kTerminator) {
// If there appears to be more data left in the section after the
// terminating mark, warn the user. But this is just a warning;
// we leave all_ok true.
if (fde.end < buffer_end) reporter_->EarlyEHTerminator(fde.offset);
break;
}
// In this loop, we skip CIEs. We only parse them fully when we
// parse an FDE that refers to them. This limits our memory
// consumption (beyond the buffer itself) to that needed to
// process the largest single entry.
if (fde.kind != kFDE) {
ok = true;
continue;
}
// Validate the CIE pointer.
if (fde.id > buffer_length_) {
reporter_->CIEPointerOutOfRange(fde.offset, fde.id);
continue;
}
CIE cie;
// Parse this FDE's CIE header.
if (!ReadEntryPrologue(buffer_ + fde.id, &cie))
continue;
// This had better be an actual CIE.
if (cie.kind != kCIE) {
reporter_->BadCIEId(fde.offset, fde.id);
continue;
}
if (!ReadCIEFields(&cie))
continue;
// TODO(nbilling): This could lead to strange behavior if a single buffer
// contained a mixture of DWARF versions as well as address sizes. Not
// sure if it's worth handling such a case.
// DWARF4 CIE specifies address_size, so use it for this call frame.
if (cie.version >= 4) {
reader_->SetAddressSize(cie.address_size);
}
// We now have the values that govern both the CIE and the FDE.
cie.cie = &cie;
fde.cie = &cie;
// Parse the FDE's header.
if (!ReadFDEFields(&fde))
continue;
// Call Entry to ask the consumer if they're interested.
if (!handler_->Entry(fde.offset, fde.address, fde.size,
cie.version, cie.augmentation,
cie.return_address_register)) {
// The handler isn't interested in this entry. That's not an error.
ok = true;
continue;
}
if (cie.has_z_augmentation) {
// Report the personality routine address, if we have one.
if (cie.has_z_personality) {
if (!handler_
->PersonalityRoutine(cie.personality_address,
IsIndirectEncoding(cie.personality_encoding)))
continue;
}
// Report the language-specific data area address, if we have one.
if (cie.has_z_lsda) {
if (!handler_
->LanguageSpecificDataArea(fde.lsda_address,
IsIndirectEncoding(cie.lsda_encoding)))
continue;
}
// If this is a signal-handling frame, report that.
if (cie.has_z_signal_frame) {
if (!handler_->SignalHandler())
continue;
}
}
// Interpret the CIE's instructions, and then the FDE's instructions.
State state(reader_, handler_, reporter_, fde.address);
ok = state.InterpretCIE(cie) && state.InterpretFDE(fde);
// Tell the ByteReader that the function start address from the
// FDE header is no longer valid.
reader_->ClearFunctionBase();
// Report the end of the entry.
handler_->End();
}
return all_ok;
}
const char* CallFrameInfo::KindName(EntryKind kind) {
if (kind == CallFrameInfo::kUnknown)
return "entry";
else if (kind == CallFrameInfo::kCIE)
return "common information entry";
else if (kind == CallFrameInfo::kFDE)
return "frame description entry";
else {
assert (kind == CallFrameInfo::kTerminator);
return ".eh_frame sequence terminator";
}
}
bool CallFrameInfo::ReportIncomplete(Entry* entry) {
reporter_->Incomplete(entry->offset, entry->kind);
return false;
}
void CallFrameInfo::Reporter::Incomplete(uint64_t offset,
CallFrameInfo::EntryKind kind) {
fprintf(stderr,
"%s: CFI %s at offset 0x%" PRIx64 " in '%s': entry ends early\n",
filename_.c_str(), CallFrameInfo::KindName(kind), offset,
section_.c_str());
}
void CallFrameInfo::Reporter::EarlyEHTerminator(uint64_t offset) {
fprintf(stderr,
"%s: CFI at offset 0x%" PRIx64 " in '%s': saw end-of-data marker"
" before end of section contents\n",
filename_.c_str(), offset, section_.c_str());
}
void CallFrameInfo::Reporter::CIEPointerOutOfRange(uint64_t offset,
uint64_t cie_offset) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE pointer is out of range: 0x%" PRIx64 "\n",
filename_.c_str(), offset, section_.c_str(), cie_offset);
}
void CallFrameInfo::Reporter::BadCIEId(uint64_t offset, uint64_t cie_offset) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE pointer does not point to a CIE: 0x%" PRIx64 "\n",
filename_.c_str(), offset, section_.c_str(), cie_offset);
}
void CallFrameInfo::Reporter::UnexpectedAddressSize(uint64_t offset,
uint8_t address_size) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE specifies unexpected address size: %d\n",
filename_.c_str(), offset, section_.c_str(), address_size);
}
void CallFrameInfo::Reporter::UnexpectedSegmentSize(uint64_t offset,
uint8_t segment_size) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE specifies unexpected segment size: %d\n",
filename_.c_str(), offset, section_.c_str(), segment_size);
}
void CallFrameInfo::Reporter::UnrecognizedVersion(uint64_t offset, int version) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE specifies unrecognized version: %d\n",
filename_.c_str(), offset, section_.c_str(), version);
}
void CallFrameInfo::Reporter::UnrecognizedAugmentation(uint64_t offset,
const string& aug) {
fprintf(stderr,
"%s: CFI frame description entry at offset 0x%" PRIx64 " in '%s':"
" CIE specifies unrecognized augmentation: '%s'\n",
filename_.c_str(), offset, section_.c_str(), aug.c_str());
}
void CallFrameInfo::Reporter::InvalidPointerEncoding(uint64_t offset,
uint8_t encoding) {
fprintf(stderr,
"%s: CFI common information entry at offset 0x%" PRIx64 " in '%s':"
" 'z' augmentation specifies invalid pointer encoding: 0x%02x\n",
filename_.c_str(), offset, section_.c_str(), encoding);
}
void CallFrameInfo::Reporter::UnusablePointerEncoding(uint64_t offset,
uint8_t encoding) {
fprintf(stderr,
"%s: CFI common information entry at offset 0x%" PRIx64 " in '%s':"
" 'z' augmentation specifies a pointer encoding for which"
" we have no base address: 0x%02x\n",
filename_.c_str(), offset, section_.c_str(), encoding);
}
void CallFrameInfo::Reporter::RestoreInCIE(uint64_t offset, uint64_t insn_offset) {
fprintf(stderr,
"%s: CFI common information entry at offset 0x%" PRIx64 " in '%s':"
" the DW_CFA_restore instruction at offset 0x%" PRIx64
" cannot be used in a common information entry\n",
filename_.c_str(), offset, section_.c_str(), insn_offset);
}
void CallFrameInfo::Reporter::BadInstruction(uint64_t offset,
CallFrameInfo::EntryKind kind,
uint64_t insn_offset) {
fprintf(stderr,
"%s: CFI %s at offset 0x%" PRIx64 " in section '%s':"
" the instruction at offset 0x%" PRIx64 " is unrecognized\n",
filename_.c_str(), CallFrameInfo::KindName(kind),
offset, section_.c_str(), insn_offset);
}
void CallFrameInfo::Reporter::NoCFARule(uint64_t offset,
CallFrameInfo::EntryKind kind,
uint64_t insn_offset) {
fprintf(stderr,
"%s: CFI %s at offset 0x%" PRIx64 " in section '%s':"
" the instruction at offset 0x%" PRIx64 " assumes that a CFA rule has"
" been set, but none has been set\n",
filename_.c_str(), CallFrameInfo::KindName(kind), offset,
section_.c_str(), insn_offset);
}
void CallFrameInfo::Reporter::EmptyStateStack(uint64_t offset,
CallFrameInfo::EntryKind kind,
uint64_t insn_offset) {
fprintf(stderr,
"%s: CFI %s at offset 0x%" PRIx64 " in section '%s':"
" the DW_CFA_restore_state instruction at offset 0x%" PRIx64
" should pop a saved state from the stack, but the stack is empty\n",
filename_.c_str(), CallFrameInfo::KindName(kind), offset,
section_.c_str(), insn_offset);
}
void CallFrameInfo::Reporter::ClearingCFARule(uint64_t offset,
CallFrameInfo::EntryKind kind,
uint64_t insn_offset) {
fprintf(stderr,
"%s: CFI %s at offset 0x%" PRIx64 " in section '%s':"
" the DW_CFA_restore_state instruction at offset 0x%" PRIx64
" would clear the CFA rule in effect\n",
filename_.c_str(), CallFrameInfo::KindName(kind), offset,
section_.c_str(), insn_offset);
}
} // namespace dwarf2reader
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