// dwarf_reader.cc -- parse dwarf2/3 debug information
// Copyright (C) 2007-2018 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include <algorithm>
#include <utility>
#include <vector>
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "object.h"
#include "reloc.h"
#include "dwarf_reader.h"
#include "int_encoding.h"
#include "compressed_output.h"
namespace gold {
// Class Sized_elf_reloc_mapper
// Initialize the relocation tracker for section RELOC_SHNDX.
template<int size, bool big_endian>
bool
Sized_elf_reloc_mapper<size, big_endian>::do_initialize(
unsigned int reloc_shndx, unsigned int reloc_type)
{
this->reloc_type_ = reloc_type;
return this->track_relocs_.initialize(this->object_, reloc_shndx,
reloc_type);
}
// Looks in the symtab to see what section a symbol is in.
template<int size, bool big_endian>
unsigned int
Sized_elf_reloc_mapper<size, big_endian>::symbol_section(
unsigned int symndx, Address* value, bool* is_ordinary)
{
const int symsize = elfcpp::Elf_sizes<size>::sym_size;
gold_assert(static_cast<off_t>((symndx + 1) * symsize) <= this->symtab_size_);
elfcpp::Sym<size, big_endian> elfsym(this->symtab_ + symndx * symsize);
*value = elfsym.get_st_value();
return this->object_->adjust_sym_shndx(symndx, elfsym.get_st_shndx(),
is_ordinary);
}
// Return the section index and offset within the section of
// the target of the relocation for RELOC_OFFSET.
template<int size, bool big_endian>
unsigned int
Sized_elf_reloc_mapper<size, big_endian>::do_get_reloc_target(
off_t reloc_offset, off_t* target_offset)
{
this->track_relocs_.advance(reloc_offset);
if (reloc_offset != this->track_relocs_.next_offset())
return 0;
unsigned int symndx = this->track_relocs_.next_symndx();
typename elfcpp::Elf_types<size>::Elf_Addr value;
bool is_ordinary;
unsigned int target_shndx = this->symbol_section(symndx, &value,
&is_ordinary);
if (!is_ordinary)
return 0;
if (this->reloc_type_ == elfcpp::SHT_RELA)
value += this->track_relocs_.next_addend();
*target_offset = value;
return target_shndx;
}
static inline Elf_reloc_mapper*
make_elf_reloc_mapper(Relobj* object, const unsigned char* symtab,
off_t symtab_size)
{
if (object->elfsize() == 32)
{
if (object->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
return new Sized_elf_reloc_mapper<32, true>(object, symtab,
symtab_size);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
return new Sized_elf_reloc_mapper<32, false>(object, symtab,
symtab_size);
#else
gold_unreachable();
#endif
}
}
else if (object->elfsize() == 64)
{
if (object->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
return new Sized_elf_reloc_mapper<64, true>(object, symtab,
symtab_size);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
return new Sized_elf_reloc_mapper<64, false>(object, symtab,
symtab_size);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
// class Dwarf_abbrev_table
void
Dwarf_abbrev_table::clear_abbrev_codes()
{
for (unsigned int code = 0; code < this->low_abbrev_code_max_; ++code)
{
if (this->low_abbrev_codes_[code] != NULL)
{
delete this->low_abbrev_codes_[code];
this->low_abbrev_codes_[code] = NULL;
}
}
for (Abbrev_code_table::iterator it = this->high_abbrev_codes_.begin();
it != this->high_abbrev_codes_.end();
++it)
{
if (it->second != NULL)
delete it->second;
}
this->high_abbrev_codes_.clear();
}
// Read the abbrev table from an object file.
bool
Dwarf_abbrev_table::do_read_abbrevs(
Relobj* object,
unsigned int abbrev_shndx,
off_t abbrev_offset)
{
this->clear_abbrev_codes();
// If we don't have relocations, abbrev_shndx will be 0, and
// we'll have to hunt for the .debug_abbrev section.
if (abbrev_shndx == 0 && this->abbrev_shndx_ > 0)
abbrev_shndx = this->abbrev_shndx_;
else if (abbrev_shndx == 0)
{
for (unsigned int i = 1; i < object->shnum(); ++i)
{
std::string name = object->section_name(i);
if (name == ".debug_abbrev" || name == ".zdebug_abbrev")
{
abbrev_shndx = i;
// Correct the offset. For incremental update links, we have a
// relocated offset that is relative to the output section, but
// here we need an offset relative to the input section.
abbrev_offset -= object->output_section_offset(i);
break;
}
}
if (abbrev_shndx == 0)
return false;
}
// Get the section contents and decompress if necessary.
if (abbrev_shndx != this->abbrev_shndx_)
{
if (this->owns_buffer_ && this->buffer_ != NULL)
{
delete[] this->buffer_;
this->owns_buffer_ = false;
}
section_size_type buffer_size;
this->buffer_ =
object->decompressed_section_contents(abbrev_shndx,
&buffer_size,
&this->owns_buffer_);
this->buffer_end_ = this->buffer_ + buffer_size;
this->abbrev_shndx_ = abbrev_shndx;
}
this->buffer_pos_ = this->buffer_ + abbrev_offset;
return true;
}
// Lookup the abbrev code entry for CODE. This function is called
// only when the abbrev code is not in the direct lookup table.
// It may be in the hash table, it may not have been read yet,
// or it may not exist in the abbrev table.
const Dwarf_abbrev_table::Abbrev_code*
Dwarf_abbrev_table::do_get_abbrev(unsigned int code)
{
// See if the abbrev code is already in the hash table.
Abbrev_code_table::const_iterator it = this->high_abbrev_codes_.find(code);
if (it != this->high_abbrev_codes_.end())
return it->second;
// Read and store abbrev code definitions until we find the
// one we're looking for.
for (;;)
{
// Read the abbrev code. A zero here indicates the end of the
// abbrev table.
size_t len;
if (this->buffer_pos_ >= this->buffer_end_)
return NULL;
uint64_t nextcode = read_unsigned_LEB_128(this->buffer_pos_, &len);
if (nextcode == 0)
{
this->buffer_pos_ = this->buffer_end_;
return NULL;
}
this->buffer_pos_ += len;
// Read the tag.
if (this->buffer_pos_ >= this->buffer_end_)
return NULL;
uint64_t tag = read_unsigned_LEB_128(this->buffer_pos_, &len);
this->buffer_pos_ += len;
// Read the has_children flag.
if (this->buffer_pos_ >= this->buffer_end_)
return NULL;
bool has_children = *this->buffer_pos_ == elfcpp::DW_CHILDREN_yes;
this->buffer_pos_ += 1;
// Read the list of (attribute, form) pairs.
Abbrev_code* entry = new Abbrev_code(tag, has_children);
for (;;)
{
// Read the attribute.
if (this->buffer_pos_ >= this->buffer_end_)
/* There is a potential resource leak here, but it is not important. */
/* coverity[leaked_storage: FALSE] */
return NULL;
uint64_t attr = read_unsigned_LEB_128(this->buffer_pos_, &len);
this->buffer_pos_ += len;
// Read the form.
if (this->buffer_pos_ >= this->buffer_end_)
/* There is a potential resource leak here, but it is not important. */
/* coverity[leaked_storage: FALSE] */
return NULL;
uint64_t form = read_unsigned_LEB_128(this->buffer_pos_, &len);
this->buffer_pos_ += len;
// A (0,0) pair terminates the list.
if (attr == 0 && form == 0)
break;
if (attr == elfcpp::DW_AT_sibling)
entry->has_sibling_attribute = true;
entry->add_attribute(attr, form);
}
this->store_abbrev(nextcode, entry);
if (nextcode == code)
return entry;
}
return NULL;
}
// class Dwarf_ranges_table
// Read the ranges table from an object file.
bool
Dwarf_ranges_table::read_ranges_table(
Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int ranges_shndx)
{
// If we've already read this abbrev table, return immediately.
if (this->ranges_shndx_ > 0
&& this->ranges_shndx_ == ranges_shndx)
return true;
// If we don't have relocations, ranges_shndx will be 0, and
// we'll have to hunt for the .debug_ranges section.
if (ranges_shndx == 0 && this->ranges_shndx_ > 0)
ranges_shndx = this->ranges_shndx_;
else if (ranges_shndx == 0)
{
for (unsigned int i = 1; i < object->shnum(); ++i)
{
std::string name = object->section_name(i);
if (name == ".debug_ranges" || name == ".zdebug_ranges")
{
ranges_shndx = i;
this->output_section_offset_ = object->output_section_offset(i);
break;
}
}
if (ranges_shndx == 0)
return false;
}
// Get the section contents and decompress if necessary.
if (ranges_shndx != this->ranges_shndx_)
{
if (this->owns_ranges_buffer_ && this->ranges_buffer_ != NULL)
{
delete[] this->ranges_buffer_;
this->owns_ranges_buffer_ = false;
}
section_size_type buffer_size;
this->ranges_buffer_ =
object->decompressed_section_contents(ranges_shndx,
&buffer_size,
&this->owns_ranges_buffer_);
this->ranges_buffer_end_ = this->ranges_buffer_ + buffer_size;
this->ranges_shndx_ = ranges_shndx;
}
if (this->ranges_reloc_mapper_ != NULL)
{
delete this->ranges_reloc_mapper_;
this->ranges_reloc_mapper_ = NULL;
}
// For incremental objects, we have no relocations.
if (object->is_incremental())
return true;
// Find the relocation section for ".debug_ranges".
unsigned int reloc_shndx = 0;
unsigned int reloc_type = 0;
for (unsigned int i = 0; i < object->shnum(); ++i)
{
reloc_type = object->section_type(i);
if ((reloc_type == elfcpp::SHT_REL
|| reloc_type == elfcpp::SHT_RELA)
&& object->section_info(i) == ranges_shndx)
{
reloc_shndx = i;
break;
}
}
this->ranges_reloc_mapper_ = make_elf_reloc_mapper(object, symtab,
symtab_size);
this->ranges_reloc_mapper_->initialize(reloc_shndx, reloc_type);
this->reloc_type_ = reloc_type;
return true;
}
// Read a range list from section RANGES_SHNDX at offset RANGES_OFFSET.
Dwarf_range_list*
Dwarf_ranges_table::read_range_list(
Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int addr_size,
unsigned int ranges_shndx,
off_t offset)
{
Dwarf_range_list* ranges;
if (!this->read_ranges_table(object, symtab, symtab_size, ranges_shndx))
return NULL;
// Correct the offset. For incremental update links, we have a
// relocated offset that is relative to the output section, but
// here we need an offset relative to the input section.
offset -= this->output_section_offset_;
// Read the range list at OFFSET.
ranges = new Dwarf_range_list();
off_t base = 0;
for (;
this->ranges_buffer_ + offset < this->ranges_buffer_end_;
offset += 2 * addr_size)
{
off_t start;
off_t end;
// Read the raw contents of the section.
if (addr_size == 4)
{
start = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_
+ offset);
end = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_
+ offset + 4);
}
else
{
start = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_
+ offset);
end = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_
+ offset + 8);
}
// Check for relocations and adjust the values.
unsigned int shndx1 = 0;
unsigned int shndx2 = 0;
if (this->ranges_reloc_mapper_ != NULL)
{
shndx1 = this->lookup_reloc(offset, &start);
shndx2 = this->lookup_reloc(offset + addr_size, &end);
}
// End of list is marked by a pair of zeroes.
if (shndx1 == 0 && start == 0 && end == 0)
break;
// A "base address selection entry" is identified by
// 0xffffffff for the first value of the pair. The second
// value is used as a base for subsequent range list entries.
if (shndx1 == 0 && start == -1)
base = end;
else if (shndx1 == shndx2)
{
if (shndx1 == 0 || object->is_section_included(shndx1))
ranges->add(shndx1, base + start, base + end);
}
else
gold_warning(_("%s: DWARF info may be corrupt; offsets in a "
"range list entry are in different sections"),
object->name().c_str());
}
return ranges;
}
// Look for a relocation at offset OFF in the range table,
// and return the section index and offset of the target.
unsigned int
Dwarf_ranges_table::lookup_reloc(off_t off, off_t* target_off)
{
off_t value;
unsigned int shndx =
this->ranges_reloc_mapper_->get_reloc_target(off, &value);
if (shndx == 0)
return 0;
if (this->reloc_type_ == elfcpp::SHT_REL)
*target_off += value;
else
*target_off = value;
return shndx;
}
// class Dwarf_pubnames_table
// Read the pubnames section from the object file.
bool
Dwarf_pubnames_table::read_section(Relobj* object, const unsigned char* symtab,
off_t symtab_size)
{
section_size_type buffer_size;
unsigned int shndx = 0;
const char* name = this->is_pubtypes_ ? "pubtypes" : "pubnames";
const char* gnu_name = (this->is_pubtypes_
? "gnu_pubtypes"
: "gnu_pubnames");
for (unsigned int i = 1; i < object->shnum(); ++i)
{
std::string section_name = object->section_name(i);
const char* section_name_suffix = section_name.c_str();
if (is_prefix_of(".debug_", section_name_suffix))
section_name_suffix += 7;
else if (is_prefix_of(".zdebug_", section_name_suffix))
section_name_suffix += 8;
else
continue;
if (strcmp(section_name_suffix, name) == 0)
{
shndx = i;
break;
}
else if (strcmp(section_name_suffix, gnu_name) == 0)
{
shndx = i;
this->is_gnu_style_ = true;
break;
}
}
if (shndx == 0)
return false;
this->buffer_ = object->decompressed_section_contents(shndx,
&buffer_size,
&this->owns_buffer_);
if (this->buffer_ == NULL)
return false;
this->buffer_end_ = this->buffer_ + buffer_size;
// For incremental objects, we have no relocations.
if (object->is_incremental())
return true;
// Find the relocation section
unsigned int reloc_shndx = 0;
unsigned int reloc_type = 0;
for (unsigned int i = 0; i < object->shnum(); ++i)
{
reloc_type = object->section_type(i);
if ((reloc_type == elfcpp::SHT_REL
|| reloc_type == elfcpp::SHT_RELA)
&& object->section_info(i) == shndx)
{
reloc_shndx = i;
break;
}
}
this->reloc_mapper_ = make_elf_reloc_mapper(object, symtab, symtab_size);
this->reloc_mapper_->initialize(reloc_shndx, reloc_type);
this->reloc_type_ = reloc_type;
return true;
}
// Read the header for the set at OFFSET.
bool
Dwarf_pubnames_table::read_header(off_t offset)
{
// Make sure we have actually read the section.
gold_assert(this->buffer_ != NULL);
if (offset < 0 || offset + 14 >= this->buffer_end_ - this->buffer_)
return false;
const unsigned char* pinfo = this->buffer_ + offset;
// Read the unit_length field.
uint64_t unit_length = this->dwinfo_->read_from_pointer<32>(pinfo);
pinfo += 4;
if (unit_length == 0xffffffff)
{
unit_length = this->dwinfo_->read_from_pointer<64>(pinfo);
this->unit_length_ = unit_length + 12;
pinfo += 8;
this->offset_size_ = 8;
}
else
{
this->unit_length_ = unit_length + 4;
this->offset_size_ = 4;
}
this->end_of_table_ = pinfo + unit_length;
// If unit_length is too big, maybe we should reject the whole table,
// but in cases we know about, it seems OK to assume that the table
// is valid through the actual end of the section.
if (this->end_of_table_ > this->buffer_end_)
this->end_of_table_ = this->buffer_end_;
// Check the version.
unsigned int version = this->dwinfo_->read_from_pointer<16>(pinfo);
pinfo += 2;
if (version != 2)
return false;
this->reloc_mapper_->get_reloc_target(pinfo - this->buffer_,
&this->cu_offset_);
// Skip the debug_info_offset and debug_info_size fields.
pinfo += 2 * this->offset_size_;
if (pinfo >= this->buffer_end_)
return false;
this->pinfo_ = pinfo;
return true;
}
// Read the next name from the set.
const char*
Dwarf_pubnames_table::next_name(uint8_t* flag_byte)
{
const unsigned char* pinfo = this->pinfo_;
// Check for end of list. The table should be terminated by an
// entry containing nothing but a DIE offset of 0.
if (pinfo + this->offset_size_ >= this->end_of_table_)
return NULL;
// Skip the offset within the CU. If this is zero, but we're not
// at the end of the table, then we have a real pubnames entry
// whose DIE offset is 0 (likely to be a GCC bug). Since we
// don't actually use the DIE offset in building .gdb_index,
// it's harmless.
pinfo += this->offset_size_;
if (this->is_gnu_style_)
*flag_byte = *pinfo++;
else
*flag_byte = 0;
// Return a pointer to the string at the current location,
// and advance the pointer to the next entry.
const char* ret = reinterpret_cast<const char*>(pinfo);
while (pinfo < this->buffer_end_ && *pinfo != '\0')
++pinfo;
if (pinfo < this->buffer_end_)
++pinfo;
this->pinfo_ = pinfo;
return ret;
}
// class Dwarf_die
Dwarf_die::Dwarf_die(
Dwarf_info_reader* dwinfo,
off_t die_offset,
Dwarf_die* parent)
: dwinfo_(dwinfo), parent_(parent), die_offset_(die_offset),
child_offset_(0), sibling_offset_(0), abbrev_code_(NULL), attributes_(),
attributes_read_(false), name_(NULL), name_off_(-1), linkage_name_(NULL),
linkage_name_off_(-1), string_shndx_(0), specification_(0),
abstract_origin_(0)
{
size_t len;
const unsigned char* pdie = dwinfo->buffer_at_offset(die_offset);
if (pdie == NULL)
return;
unsigned int code = read_unsigned_LEB_128(pdie, &len);
if (code == 0)
{
if (parent != NULL)
parent->set_sibling_offset(die_offset + len);
return;
}
this->attr_offset_ = len;
// Lookup the abbrev code in the abbrev table.
this->abbrev_code_ = dwinfo->get_abbrev(code);
}
// Read all the attributes of the DIE.
bool
Dwarf_die::read_attributes()
{
if (this->attributes_read_)
return true;
gold_assert(this->abbrev_code_ != NULL);
const unsigned char* pdie =
this->dwinfo_->buffer_at_offset(this->die_offset_);
if (pdie == NULL)
return false;
const unsigned char* pattr = pdie + this->attr_offset_;
unsigned int nattr = this->abbrev_code_->attributes.size();
this->attributes_.reserve(nattr);
for (unsigned int i = 0; i < nattr; ++i)
{
size_t len;
unsigned int attr = this->abbrev_code_->attributes[i].attr;
unsigned int form = this->abbrev_code_->attributes[i].form;
if (form == elfcpp::DW_FORM_indirect)
{
form = read_unsigned_LEB_128(pattr, &len);
pattr += len;
}
off_t attr_off = this->die_offset_ + (pattr - pdie);
bool ref_form = false;
Attribute_value attr_value;
attr_value.attr = attr;
attr_value.form = form;
attr_value.aux.shndx = 0;
switch(form)
{
case elfcpp::DW_FORM_flag_present:
attr_value.val.intval = 1;
break;
case elfcpp::DW_FORM_strp:
{
off_t str_off;
if (this->dwinfo_->offset_size() == 4)
str_off = this->dwinfo_->read_from_pointer<32>(&pattr);
else
str_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &str_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = str_off;
break;
}
case elfcpp::DW_FORM_sec_offset:
{
off_t sec_off;
if (this->dwinfo_->offset_size() == 4)
sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
else
sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = sec_off;
ref_form = true;
break;
}
case elfcpp::DW_FORM_addr:
{
off_t sec_off;
if (this->dwinfo_->address_size() == 4)
sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
else
sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = sec_off;
ref_form = true;
break;
}
case elfcpp::DW_FORM_ref_addr:
{
off_t sec_off;
if (this->dwinfo_->ref_addr_size() == 4)
sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
else
sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = sec_off;
ref_form = true;
break;
}
case elfcpp::DW_FORM_block1:
attr_value.aux.blocklen = *pattr++;
attr_value.val.blockval = pattr;
pattr += attr_value.aux.blocklen;
break;
case elfcpp::DW_FORM_block2:
attr_value.aux.blocklen =
this->dwinfo_->read_from_pointer<16>(&pattr);
attr_value.val.blockval = pattr;
pattr += attr_value.aux.blocklen;
break;
case elfcpp::DW_FORM_block4:
attr_value.aux.blocklen =
this->dwinfo_->read_from_pointer<32>(&pattr);
attr_value.val.blockval = pattr;
pattr += attr_value.aux.blocklen;
break;
case elfcpp::DW_FORM_block:
case elfcpp::DW_FORM_exprloc:
attr_value.aux.blocklen = read_unsigned_LEB_128(pattr, &len);
attr_value.val.blockval = pattr + len;
pattr += len + attr_value.aux.blocklen;
break;
case elfcpp::DW_FORM_data1:
case elfcpp::DW_FORM_flag:
attr_value.val.intval = *pattr++;
break;
case elfcpp::DW_FORM_ref1:
attr_value.val.refval = *pattr++;
ref_form = true;
break;
case elfcpp::DW_FORM_data2:
attr_value.val.intval =
this->dwinfo_->read_from_pointer<16>(&pattr);
break;
case elfcpp::DW_FORM_ref2:
attr_value.val.refval =
this->dwinfo_->read_from_pointer<16>(&pattr);
ref_form = true;
break;
case elfcpp::DW_FORM_data4:
{
off_t sec_off;
sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.intval = sec_off;
break;
}
case elfcpp::DW_FORM_ref4:
{
off_t sec_off;
sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = sec_off;
ref_form = true;
break;
}
case elfcpp::DW_FORM_data8:
{
off_t sec_off;
sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.intval = sec_off;
break;
}
case elfcpp::DW_FORM_ref_sig8:
attr_value.val.uintval =
this->dwinfo_->read_from_pointer<64>(&pattr);
break;
case elfcpp::DW_FORM_ref8:
{
off_t sec_off;
sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
unsigned int shndx =
this->dwinfo_->lookup_reloc(attr_off, &sec_off);
attr_value.aux.shndx = shndx;
attr_value.val.refval = sec_off;
ref_form = true;
break;
}
case elfcpp::DW_FORM_ref_udata:
attr_value.val.refval = read_unsigned_LEB_128(pattr, &len);
ref_form = true;
pattr += len;
break;
case elfcpp::DW_FORM_udata:
case elfcpp::DW_FORM_GNU_addr_index:
case elfcpp::DW_FORM_GNU_str_index:
attr_value.val.uintval = read_unsigned_LEB_128(pattr, &len);
pattr += len;
break;
case elfcpp::DW_FORM_sdata:
attr_value.val.intval = read_signed_LEB_128(pattr, &len);
pattr += len;
break;
case elfcpp::DW_FORM_string:
attr_value.val.stringval = reinterpret_cast<const char*>(pattr);
len = strlen(attr_value.val.stringval);
pattr += len + 1;
break;
default:
return false;
}
// Cache the most frequently-requested attributes.
switch (attr)
{
case elfcpp::DW_AT_name:
if (form == elfcpp::DW_FORM_string)
this->name_ = attr_value.val.stringval;
else if (form == elfcpp::DW_FORM_strp)
{
// All indirect strings should refer to the same
// string section, so we just save the last one seen.
this->string_shndx_ = attr_value.aux.shndx;
this->name_off_ = attr_value.val.refval;
}
break;
case elfcpp::DW_AT_linkage_name:
case elfcpp::DW_AT_MIPS_linkage_name:
if (form == elfcpp::DW_FORM_string)
this->linkage_name_ = attr_value.val.stringval;
else if (form == elfcpp::DW_FORM_strp)
{
// All indirect strings should refer to the same
// string section, so we just save the last one seen.
this->string_shndx_ = attr_value.aux.shndx;
this->linkage_name_off_ = attr_value.val.refval;
}
break;
case elfcpp::DW_AT_specification:
if (ref_form)
this->specification_ = attr_value.val.refval;
break;
case elfcpp::DW_AT_abstract_origin:
if (ref_form)
this->abstract_origin_ = attr_value.val.refval;
break;
case elfcpp::DW_AT_sibling:
if (ref_form && attr_value.aux.shndx == 0)
this->sibling_offset_ = attr_value.val.refval;
default:
break;
}
this->attributes_.push_back(attr_value);
}
// Now that we know where the next DIE begins, record the offset
// to avoid later recalculation.
if (this->has_children())
this->child_offset_ = this->die_offset_ + (pattr - pdie);
else
this->sibling_offset_ = this->die_offset_ + (pattr - pdie);
this->attributes_read_ = true;
return true;
}
// Skip all the attributes of the DIE and return the offset of the next DIE.
off_t
Dwarf_die::skip_attributes()
{
gold_assert(this->abbrev_code_ != NULL);
const unsigned char* pdie =
this->dwinfo_->buffer_at_offset(this->die_offset_);
if (pdie == NULL)
return 0;
const unsigned char* pattr = pdie + this->attr_offset_;
for (unsigned int i = 0; i < this->abbrev_code_->attributes.size(); ++i)
{
size_t len;
unsigned int form = this->abbrev_code_->attributes[i].form;
if (form == elfcpp::DW_FORM_indirect)
{
form = read_unsigned_LEB_128(pattr, &len);
pattr += len;
}
switch(form)
{
case elfcpp::DW_FORM_flag_present:
break;
case elfcpp::DW_FORM_strp:
case elfcpp::DW_FORM_sec_offset:
pattr += this->dwinfo_->offset_size();
break;
case elfcpp::DW_FORM_addr:
pattr += this->dwinfo_->address_size();
break;
case elfcpp::DW_FORM_ref_addr:
pattr += this->dwinfo_->ref_addr_size();
break;
case elfcpp::DW_FORM_block1:
pattr += 1 + *pattr;
break;
case elfcpp::DW_FORM_block2:
{
uint16_t block_size;
block_size = this->dwinfo_->read_from_pointer<16>(&pattr);
pattr += block_size;
break;
}
case elfcpp::DW_FORM_block4:
{
uint32_t block_size;
block_size = this->dwinfo_->read_from_pointer<32>(&pattr);
pattr += block_size;
break;
}
case elfcpp::DW_FORM_block:
case elfcpp::DW_FORM_exprloc:
{
uint64_t block_size;
block_size = read_unsigned_LEB_128(pattr, &len);
pattr += len + block_size;
break;
}
case elfcpp::DW_FORM_data1:
case elfcpp::DW_FORM_ref1:
case elfcpp::DW_FORM_flag:
pattr += 1;
break;
case elfcpp::DW_FORM_data2:
case elfcpp::DW_FORM_ref2:
pattr += 2;
break;
case elfcpp::DW_FORM_data4:
case elfcpp::DW_FORM_ref4:
pattr += 4;
break;
case elfcpp::DW_FORM_data8:
case elfcpp::DW_FORM_ref8:
case elfcpp::DW_FORM_ref_sig8:
pattr += 8;
break;
case elfcpp::DW_FORM_ref_udata:
case elfcpp::DW_FORM_udata:
case elfcpp::DW_FORM_GNU_addr_index:
case elfcpp::DW_FORM_GNU_str_index:
read_unsigned_LEB_128(pattr, &len);
pattr += len;
break;
case elfcpp::DW_FORM_sdata:
read_signed_LEB_128(pattr, &len);
pattr += len;
break;
case elfcpp::DW_FORM_string:
len = strlen(reinterpret_cast<const char*>(pattr));
pattr += len + 1;
break;
default:
return 0;
}
}
return this->die_offset_ + (pattr - pdie);
}
// Get the name of the DIE and cache it.
void
Dwarf_die::set_name()
{
if (this->name_ != NULL || !this->read_attributes())
return;
if (this->name_off_ != -1)
this->name_ = this->dwinfo_->get_string(this->name_off_,
this->string_shndx_);
}
// Get the linkage name of the DIE and cache it.
void
Dwarf_die::set_linkage_name()
{
if (this->linkage_name_ != NULL || !this->read_attributes())
return;
if (this->linkage_name_off_ != -1)
this->linkage_name_ = this->dwinfo_->get_string(this->linkage_name_off_,
this->string_shndx_);
}
// Return the value of attribute ATTR.
const Dwarf_die::Attribute_value*
Dwarf_die::attribute(unsigned int attr)
{
if (!this->read_attributes())
return NULL;
for (unsigned int i = 0; i < this->attributes_.size(); ++i)
{
if (this->attributes_[i].attr == attr)
return &this->attributes_[i];
}
return NULL;
}
const char*
Dwarf_die::string_attribute(unsigned int attr)
{
const Attribute_value* attr_val = this->attribute(attr);
if (attr_val == NULL)
return NULL;
switch (attr_val->form)
{
case elfcpp::DW_FORM_string:
return attr_val->val.stringval;
case elfcpp::DW_FORM_strp:
return this->dwinfo_->get_string(attr_val->val.refval,
attr_val->aux.shndx);
default:
return NULL;
}
}
int64_t
Dwarf_die::int_attribute(unsigned int attr)
{
const Attribute_value* attr_val = this->attribute(attr);
if (attr_val == NULL)
return 0;
switch (attr_val->form)
{
case elfcpp::DW_FORM_flag_present:
case elfcpp::DW_FORM_data1:
case elfcpp::DW_FORM_flag:
case elfcpp::DW_FORM_data2:
case elfcpp::DW_FORM_data4:
case elfcpp::DW_FORM_data8:
case elfcpp::DW_FORM_sdata:
return attr_val->val.intval;
default:
return 0;
}
}
uint64_t
Dwarf_die::uint_attribute(unsigned int attr)
{
const Attribute_value* attr_val = this->attribute(attr);
if (attr_val == NULL)
return 0;
switch (attr_val->form)
{
case elfcpp::DW_FORM_flag_present:
case elfcpp::DW_FORM_data1:
case elfcpp::DW_FORM_flag:
case elfcpp::DW_FORM_data4:
case elfcpp::DW_FORM_data8:
case elfcpp::DW_FORM_ref_sig8:
case elfcpp::DW_FORM_udata:
return attr_val->val.uintval;
default:
return 0;
}
}
off_t
Dwarf_die::ref_attribute(unsigned int attr, unsigned int* shndx)
{
const Attribute_value* attr_val = this->attribute(attr);
if (attr_val == NULL)
return -1;
switch (attr_val->form)
{
case elfcpp::DW_FORM_sec_offset:
case elfcpp::DW_FORM_addr:
case elfcpp::DW_FORM_ref_addr:
case elfcpp::DW_FORM_ref1:
case elfcpp::DW_FORM_ref2:
case elfcpp::DW_FORM_ref4:
case elfcpp::DW_FORM_ref8:
case elfcpp::DW_FORM_ref_udata:
*shndx = attr_val->aux.shndx;
return attr_val->val.refval;
case elfcpp::DW_FORM_ref_sig8:
*shndx = attr_val->aux.shndx;
return attr_val->val.uintval;
case elfcpp::DW_FORM_data4:
case elfcpp::DW_FORM_data8:
*shndx = attr_val->aux.shndx;
return attr_val->val.intval;
default:
return -1;
}
}
off_t
Dwarf_die::address_attribute(unsigned int attr, unsigned int* shndx)
{
const Attribute_value* attr_val = this->attribute(attr);
if (attr_val == NULL || attr_val->form != elfcpp::DW_FORM_addr)
return -1;
*shndx = attr_val->aux.shndx;
return attr_val->val.refval;
}
// Return the offset of this DIE's first child.
off_t
Dwarf_die::child_offset()
{
gold_assert(this->abbrev_code_ != NULL);
if (!this->has_children())
return 0;
if (this->child_offset_ == 0)
this->child_offset_ = this->skip_attributes();
return this->child_offset_;
}
// Return the offset of this DIE's next sibling.
off_t
Dwarf_die::sibling_offset()
{
gold_assert(this->abbrev_code_ != NULL);
if (this->sibling_offset_ != 0)
return this->sibling_offset_;
if (!this->has_children())
{
this->sibling_offset_ = this->skip_attributes();
return this->sibling_offset_;
}
if (this->has_sibling_attribute())
{
if (!this->read_attributes())
return 0;
if (this->sibling_offset_ != 0)
return this->sibling_offset_;
}
// Skip over the children.
off_t child_offset = this->child_offset();
while (child_offset > 0)
{
Dwarf_die die(this->dwinfo_, child_offset, this);
// The Dwarf_die ctor will set this DIE's sibling offset
// when it reads a zero abbrev code.
if (die.tag() == 0)
break;
child_offset = die.sibling_offset();
}
// This should be set by now. If not, there was a problem reading
// the DWARF info, and we return 0.
return this->sibling_offset_;
}
// class Dwarf_info_reader
// Begin parsing the debug info. This calls visit_compilation_unit()
// or visit_type_unit() for each compilation or type unit found in the
// section, and visit_die() for each top-level DIE.
void
Dwarf_info_reader::parse()
{
if (this->object_->is_big_endian())
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
this->do_parse<true>();
#else
gold_unreachable();
#endif
}
else
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
this->do_parse<false>();
#else
gold_unreachable();
#endif
}
}
template<bool big_endian>
void
Dwarf_info_reader::do_parse()
{
// Get the section contents and decompress if necessary.
section_size_type buffer_size;
bool buffer_is_new;
this->buffer_ = this->object_->decompressed_section_contents(this->shndx_,
&buffer_size,
&buffer_is_new);
if (this->buffer_ == NULL || buffer_size == 0)
return;
this->buffer_end_ = this->buffer_ + buffer_size;
// The offset of this input section in the output section.
off_t section_offset = this->object_->output_section_offset(this->shndx_);
// Start tracking relocations for this section.
this->reloc_mapper_ = make_elf_reloc_mapper(this->object_, this->symtab_,
this->symtab_size_);
this->reloc_mapper_->initialize(this->reloc_shndx_, this->reloc_type_);
// Loop over compilation units (or type units).
unsigned int abbrev_shndx = this->abbrev_shndx_;
off_t abbrev_offset = 0;
const unsigned char* pinfo = this->buffer_;
while (pinfo < this->buffer_end_)
{
// Read the compilation (or type) unit header.
const unsigned char* cu_start = pinfo;
this->cu_offset_ = cu_start - this->buffer_;
this->cu_length_ = this->buffer_end_ - cu_start;
// Read unit_length (4 or 12 bytes).
if (!this->check_buffer(pinfo + 4))
break;
uint32_t unit_length =
elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
pinfo += 4;
if (unit_length == 0xffffffff)
{
if (!this->check_buffer(pinfo + 8))
break;
unit_length = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
pinfo += 8;
this->offset_size_ = 8;
}
else
this->offset_size_ = 4;
if (!this->check_buffer(pinfo + unit_length))
break;
const unsigned char* cu_end = pinfo + unit_length;
this->cu_length_ = cu_end - cu_start;
if (!this->check_buffer(pinfo + 2 + this->offset_size_ + 1))
break;
// Read version (2 bytes).
this->cu_version_ =
elfcpp::Swap_unaligned<16, big_endian>::readval(pinfo);
pinfo += 2;
// Read debug_abbrev_offset (4 or 8 bytes).
if (this->offset_size_ == 4)
abbrev_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
else
abbrev_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
if (this->reloc_shndx_ > 0)
{
off_t reloc_offset = pinfo - this->buffer_;
off_t value;
abbrev_shndx =
this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
if (abbrev_shndx == 0)
return;
if (this->reloc_type_ == elfcpp::SHT_REL)
abbrev_offset += value;
else
abbrev_offset = value;
}
pinfo += this->offset_size_;
// Read address_size (1 byte).
this->address_size_ = *pinfo++;
// For type units, read the two extra fields.
uint64_t signature = 0;
off_t type_offset = 0;
if (this->is_type_unit_)
{
if (!this->check_buffer(pinfo + 8 + this->offset_size_))
break;
// Read type_signature (8 bytes).
signature = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
pinfo += 8;
// Read type_offset (4 or 8 bytes).
if (this->offset_size_ == 4)
type_offset =
elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
else
type_offset =
elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
pinfo += this->offset_size_;
}
// Read the .debug_abbrev table.
this->abbrev_table_.read_abbrevs(this->object_, abbrev_shndx,
abbrev_offset);
// Visit the root DIE.
Dwarf_die root_die(this,
pinfo - (this->buffer_ + this->cu_offset_),
NULL);
if (root_die.tag() != 0)
{
// Visit the CU or TU.
if (this->is_type_unit_)
this->visit_type_unit(section_offset + this->cu_offset_,
cu_end - cu_start, type_offset, signature,
&root_die);
else
this->visit_compilation_unit(section_offset + this->cu_offset_,
cu_end - cu_start, &root_die);
}
// Advance to the next CU.
pinfo = cu_end;
}
if (buffer_is_new)
{
delete[] this->buffer_;
this->buffer_ = NULL;
}
}
// Read the DWARF string table.
bool
Dwarf_info_reader::do_read_string_table(unsigned int string_shndx)
{
Relobj* object = this->object_;
// If we don't have relocations, string_shndx will be 0, and
// we'll have to hunt for the .debug_str section.
if (string_shndx == 0)
{
for (unsigned int i = 1; i < this->object_->shnum(); ++i)
{
std::string name = object->section_name(i);
if (name == ".debug_str" || name == ".zdebug_str")
{
string_shndx = i;
this->string_output_section_offset_ =
object->output_section_offset(i);
break;
}
}
if (string_shndx == 0)
return false;
}
if (this->owns_string_buffer_ && this->string_buffer_ != NULL)
{
delete[] this->string_buffer_;
this->owns_string_buffer_ = false;
}
// Get the secton contents and decompress if necessary.
section_size_type buffer_size;
const unsigned char* buffer =
object->decompressed_section_contents(string_shndx,
&buffer_size,
&this->owns_string_buffer_);
this->string_buffer_ = reinterpret_cast<const char*>(buffer);
this->string_buffer_end_ = this->string_buffer_ + buffer_size;
this->string_shndx_ = string_shndx;
return true;
}
// Read a possibly unaligned integer of SIZE.
template <int valsize>
inline typename elfcpp::Valtype_base<valsize>::Valtype
Dwarf_info_reader::read_from_pointer(const unsigned char* source)
{
typename elfcpp::Valtype_base<valsize>::Valtype return_value;
if (this->object_->is_big_endian())
return_value = elfcpp::Swap_unaligned<valsize, true>::readval(source);
else
return_value = elfcpp::Swap_unaligned<valsize, false>::readval(source);
return return_value;
}
// Read a possibly unaligned integer of SIZE. Update SOURCE after read.
template <int valsize>
inline typename elfcpp::Valtype_base<valsize>::Valtype
Dwarf_info_reader::read_from_pointer(const unsigned char** source)
{
typename elfcpp::Valtype_base<valsize>::Valtype return_value;
if (this->object_->is_big_endian())
return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source);
else
return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source);
*source += valsize / 8;
return return_value;
}
// Look for a relocation at offset ATTR_OFF in the dwarf info,
// and return the section index and offset of the target.
unsigned int
Dwarf_info_reader::lookup_reloc(off_t attr_off, off_t* target_off)
{
off_t value;
attr_off += this->cu_offset_;
unsigned int shndx = this->reloc_mapper_->get_reloc_target(attr_off, &value);
if (shndx == 0)
return 0;
if (this->reloc_type_ == elfcpp::SHT_REL)
*target_off += value;
else
*target_off = value;
return shndx;
}
// Return a string from the DWARF string table.
const char*
Dwarf_info_reader::get_string(off_t str_off, unsigned int string_shndx)
{
if (!this->read_string_table(string_shndx))
return NULL;
// Correct the offset. For incremental update links, we have a
// relocated offset that is relative to the output section, but
// here we need an offset relative to the input section.
str_off -= this->string_output_section_offset_;
const char* p = this->string_buffer_ + str_off;
if (p < this->string_buffer_ || p >= this->string_buffer_end_)
return NULL;
return p;
}
// The following are default, do-nothing, implementations of the
// hook methods normally provided by a derived class. We provide
// default implementations rather than no implementation so that
// a derived class needs to implement only the hooks that it needs
// to use.
// Process a compilation unit and parse its child DIE.
void
Dwarf_info_reader::visit_compilation_unit(off_t, off_t, Dwarf_die*)
{
}
// Process a type unit and parse its child DIE.
void
Dwarf_info_reader::visit_type_unit(off_t, off_t, off_t, uint64_t, Dwarf_die*)
{
}
// Print a warning about a corrupt debug section.
void
Dwarf_info_reader::warn_corrupt_debug_section() const
{
gold_warning(_("%s: corrupt debug info in %s"),
this->object_->name().c_str(),
this->object_->section_name(this->shndx_).c_str());
}
// class Sized_dwarf_line_info
struct LineStateMachine
{
int file_num;
uint64_t address;
int line_num;
int column_num;
unsigned int shndx; // the section address refers to
bool is_stmt; // stmt means statement.
bool basic_block;
bool end_sequence;
};
static void
ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
{
lsm->file_num = 1;
lsm->address = 0;
lsm->line_num = 1;
lsm->column_num = 0;
lsm->shndx = -1U;
lsm->is_stmt = default_is_stmt;
lsm->basic_block = false;
lsm->end_sequence = false;
}
template<int size, bool big_endian>
Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(
Object* object,
unsigned int read_shndx)
: data_valid_(false), buffer_(NULL), buffer_start_(NULL),
reloc_mapper_(NULL), symtab_buffer_(NULL), directories_(), files_(),
current_header_index_(-1)
{
unsigned int debug_shndx;
for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
{
// FIXME: do this more efficiently: section_name() isn't super-fast
std::string name = object->section_name(debug_shndx);
if (name == ".debug_line" || name == ".zdebug_line")
{
section_size_type buffer_size;
bool is_new = false;
this->buffer_ = object->decompressed_section_contents(debug_shndx,
&buffer_size,
&is_new);
if (is_new)
this->buffer_start_ = this->buffer_;
this->buffer_end_ = this->buffer_ + buffer_size;
break;
}
}
if (this->buffer_ == NULL)
return;
// Find the relocation section for ".debug_line".
// We expect these for relobjs (.o's) but not dynobjs (.so's).
unsigned int reloc_shndx = 0;
for (unsigned int i = 0; i < object->shnum(); ++i)
{
unsigned int reloc_sh_type = object->section_type(i);
if ((reloc_sh_type == elfcpp::SHT_REL
|| reloc_sh_type == elfcpp::SHT_RELA)
&& object->section_info(i) == debug_shndx)
{
reloc_shndx = i;
this->track_relocs_type_ = reloc_sh_type;
break;
}
}
// Finally, we need the symtab section to interpret the relocs.
if (reloc_shndx != 0)
{
unsigned int symtab_shndx;
for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
{
this->symtab_buffer_ = object->section_contents(
symtab_shndx, &this->symtab_buffer_size_, false);
break;
}
if (this->symtab_buffer_ == NULL)
return;
}
this->reloc_mapper_ =
new Sized_elf_reloc_mapper<size, big_endian>(object,
this->symtab_buffer_,
this->symtab_buffer_size_);
if (!this->reloc_mapper_->initialize(reloc_shndx, this->track_relocs_type_))
return;
// Now that we have successfully read all the data, parse the debug
// info.
this->data_valid_ = true;
this->read_line_mappings(read_shndx);
}
// Read the DWARF header.
template<int size, bool big_endian>
const unsigned char*
Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
const unsigned char* lineptr)
{
uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
lineptr += 4;
// In DWARF2/3, if the initial length is all 1 bits, then the offset
// size is 8 and we need to read the next 8 bytes for the real length.
if (initial_length == 0xffffffff)
{
header_.offset_size = 8;
initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
lineptr += 8;
}
else
header_.offset_size = 4;
header_.total_length = initial_length;
gold_assert(lineptr + header_.total_length <= buffer_end_);
header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
lineptr += 2;
if (header_.offset_size == 4)
header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
else
header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
lineptr += header_.offset_size;
header_.min_insn_length = *lineptr;
lineptr += 1;
header_.default_is_stmt = *lineptr;
lineptr += 1;
header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
lineptr += 1;
header_.line_range = *lineptr;
lineptr += 1;
header_.opcode_base = *lineptr;
lineptr += 1;
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] = *lineptr;
lineptr += 1;
}
return lineptr;
}
// The header for a debug_line section is mildly complicated, because
// the line info is very tightly encoded.
template<int size, bool big_endian>
const unsigned char*
Sized_dwarf_line_info<size, big_endian>::read_header_tables(
const unsigned char* lineptr)
{
++this->current_header_index_;
// Create a new directories_ entry and a new files_ entry for our new
// header. We initialize each with a single empty element, because
// dwarf indexes directory and filenames starting at 1.
gold_assert(static_cast<int>(this->directories_.size())
== this->current_header_index_);
gold_assert(static_cast<int>(this->files_.size())
== this->current_header_index_);
this->directories_.push_back(std::vector<std::string>(1));
this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
// It is legal for the directory entry table to be empty.
if (*lineptr)
{
int dirindex = 1;
while (*lineptr)
{
const char* dirname = reinterpret_cast<const char*>(lineptr);
gold_assert(dirindex
== static_cast<int>(this->directories_.back().size()));
this->directories_.back().push_back(dirname);
lineptr += this->directories_.back().back().size() + 1;
dirindex++;
}
}
lineptr++;
// It is also legal for the file entry table to be empty.
if (*lineptr)
{
int fileindex = 1;
size_t len;
while (*lineptr)
{
const char* filename = reinterpret_cast<const char*>(lineptr);
lineptr += strlen(filename) + 1;
uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
lineptr += len;
if (dirindex >= this->directories_.back().size())
dirindex = 0;
int dirindexi = static_cast<int>(dirindex);
read_unsigned_LEB_128(lineptr, &len); // mod_time
lineptr += len;
read_unsigned_LEB_128(lineptr, &len); // filelength
lineptr += len;
gold_assert(fileindex
== static_cast<int>(this->files_.back().size()));
this->files_.back().push_back(std::make_pair(dirindexi, filename));
fileindex++;
}
}
lineptr++;
return lineptr;
}
// Process a single opcode in the .debug.line structure.
template<int size, bool big_endian>
bool
Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
{
size_t oplen = 0;
size_t templen;
unsigned char opcode = *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 int advance_address = ((opcode / header_.line_range)
* header_.min_insn_length);
lsm->address += advance_address;
const int advance_line = ((opcode % header_.line_range)
+ header_.line_base);
lsm->line_num += advance_line;
lsm->basic_block = true;
*len = oplen;
return true;
}
// Otherwise, we have the regular opcodes
switch (opcode)
{
case elfcpp::DW_LNS_copy:
lsm->basic_block = false;
*len = oplen;
return true;
case elfcpp::DW_LNS_advance_pc:
{
const uint64_t advance_address
= read_unsigned_LEB_128(start, &templen);
oplen += templen;
lsm->address += header_.min_insn_length * advance_address;
}
break;
case elfcpp::DW_LNS_advance_line:
{
const uint64_t advance_line = read_signed_LEB_128(start, &templen);
oplen += templen;
lsm->line_num += advance_line;
}
break;
case elfcpp::DW_LNS_set_file:
{
const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
oplen += templen;
lsm->file_num = fileno;
}
break;
case elfcpp::DW_LNS_set_column:
{
const uint64_t colno = read_unsigned_LEB_128(start, &templen);
oplen += templen;
lsm->column_num = colno;
}
break;
case elfcpp::DW_LNS_negate_stmt:
lsm->is_stmt = !lsm->is_stmt;
break;
case elfcpp::DW_LNS_set_basic_block:
lsm->basic_block = true;
break;
case elfcpp::DW_LNS_fixed_advance_pc:
{
int advance_address;
advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
oplen += 2;
lsm->address += advance_address;
}
break;
case elfcpp::DW_LNS_const_add_pc:
{
const int advance_address = (header_.min_insn_length
* ((255 - header_.opcode_base)
/ header_.line_range));
lsm->address += advance_address;
}
break;
case elfcpp::DW_LNS_extended_op:
{
const uint64_t extended_op_len
= read_unsigned_LEB_128(start, &templen);
start += templen;
oplen += templen + extended_op_len;
const unsigned char extended_op = *start;
start++;
switch (extended_op)
{
case elfcpp::DW_LNE_end_sequence:
// This means that the current byte is the one immediately
// after a set of instructions. Record the current line
// for up to one less than the current address.
lsm->line_num = -1;
lsm->end_sequence = true;
*len = oplen;
return true;
case elfcpp::DW_LNE_set_address:
{
lsm->address =
elfcpp::Swap_unaligned<size, big_endian>::readval(start);
typename Reloc_map::const_iterator it
= this->reloc_map_.find(start - this->buffer_);
if (it != reloc_map_.end())
{
// If this is a SHT_RELA section, then ignore the
// section contents. This assumes that this is a
// straight reloc which just uses the reloc addend.
// The reloc addend has already been included in the
// symbol value.
if (this->track_relocs_type_ == elfcpp::SHT_RELA)
lsm->address = 0;
// Add in the symbol value.
lsm->address += it->second.second;
lsm->shndx = it->second.first;
}
else
{
// If we're a normal .o file, with relocs, every
// set_address should have an associated relocation.
if (this->input_is_relobj())
this->data_valid_ = false;
}
break;
}
case elfcpp::DW_LNE_define_file:
{
const char* filename = reinterpret_cast<const char*>(start);
templen = strlen(filename) + 1;
start += templen;
uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
if (dirindex >= this->directories_.back().size())
dirindex = 0;
int dirindexi = static_cast<int>(dirindex);
// This opcode takes two additional ULEB128 parameters
// (mod_time and filelength), but we don't use those
// values. Because OPLEN already tells us how far to
// skip to the next opcode, we don't need to read
// them at all.
this->files_.back().push_back(std::make_pair(dirindexi,
filename));
}
break;
}
}
break;
default:
{
// Ignore unknown opcode silently
for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
{
size_t templen;
read_unsigned_LEB_128(start, &templen);
start += templen;
oplen += templen;
}
}
break;
}
*len = oplen;
return false;
}
// Read the debug information at LINEPTR and store it in the line
// number map.
template<int size, bool big_endian>
unsigned const char*
Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
unsigned int shndx)
{
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 unsigned char* lengthstart = buffer_;
// In 64 bit dwarf, the initial length is 12 bytes, because of the
// 0xffffffff at the start.
if (header_.offset_size == 8)
lengthstart += 12;
else
lengthstart += 4;
while (lineptr < lengthstart + header_.total_length)
{
ResetLineStateMachine(&lsm, header_.default_is_stmt);
while (!lsm.end_sequence)
{
size_t oplength;
bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
if (add_line
&& (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
{
Offset_to_lineno_entry entry
= { static_cast<off_t>(lsm.address),
this->current_header_index_,
static_cast<unsigned int>(lsm.file_num),
true, lsm.line_num };
std::vector<Offset_to_lineno_entry>&
map(this->line_number_map_[lsm.shndx]);
// If we see two consecutive entries with the same
// offset and a real line number, then mark the first
// one as non-canonical.
if (!map.empty()
&& (map.back().offset == static_cast<off_t>(lsm.address))
&& lsm.line_num != -1
&& map.back().line_num != -1)
map.back().last_line_for_offset = false;
map.push_back(entry);
}
lineptr += oplength;
}
}
return lengthstart + header_.total_length;
}
// Read the relocations into a Reloc_map.
template<int size, bool big_endian>
void
Sized_dwarf_line_info<size, big_endian>::read_relocs()
{
if (this->symtab_buffer_ == NULL)
return;
off_t value;
off_t reloc_offset;
while ((reloc_offset = this->reloc_mapper_->next_offset()) != -1)
{
const unsigned int shndx =
this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
// There is no reason to record non-ordinary section indexes, or
// SHN_UNDEF, because they will never match the real section.
if (shndx != 0)
this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
this->reloc_mapper_->advance(reloc_offset + 1);
}
}
// Read the line number info.
template<int size, bool big_endian>
void
Sized_dwarf_line_info<size, big_endian>::read_line_mappings(unsigned int shndx)
{
gold_assert(this->data_valid_ == true);
this->read_relocs();
while (this->buffer_ < this->buffer_end_)
{
const unsigned char* lineptr = this->buffer_;
lineptr = this->read_header_prolog(lineptr);
lineptr = this->read_header_tables(lineptr);
lineptr = this->read_lines(lineptr, shndx);
this->buffer_ = lineptr;
}
// Sort the lines numbers, so addr2line can use binary search.
for (typename Lineno_map::iterator it = line_number_map_.begin();
it != line_number_map_.end();
++it)
// Each vector needs to be sorted by offset.
std::sort(it->second.begin(), it->second.end());
}
// Some processing depends on whether the input is a .o file or not.
// For instance, .o files have relocs, and have .debug_lines
// information on a per section basis. .so files, on the other hand,
// lack relocs, and offsets are unique, so we can ignore the section
// information.
template<int size, bool big_endian>
bool
Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
{
// Only .o files have relocs and the symtab buffer that goes with them.
return this->symtab_buffer_ != NULL;
}
// Given an Offset_to_lineno_entry vector, and an offset, figure out
// if the offset points into a function according to the vector (see
// comments below for the algorithm). If it does, return an iterator
// into the vector that points to the line-number that contains that
// offset. If not, it returns vector::end().
static std::vector<Offset_to_lineno_entry>::const_iterator
offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
off_t offset)
{
const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
// lower_bound() returns the smallest offset which is >= lookup_key.
// If no offset in offsets is >= lookup_key, returns end().
std::vector<Offset_to_lineno_entry>::const_iterator it
= std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
// This code is easiest to understand with a concrete example.
// Here's a possible offsets array:
// {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16}, // 0
// {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20}, // 1
// {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22}, // 2
// {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25}, // 3
// {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1}, // 4
// {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65}, // 5
// {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66}, // 6
// {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1}, // 7
// {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48}, // 8
// {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47}, // 9
// {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49}, // 10
// {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50}, // 11
// {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51}, // 12
// {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1}, // 13
// {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19}, // 14
// {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20}, // 15
// {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67}, // 16
// {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1}, // 17
// {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66}, // 18
// {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68}, // 19
// {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1}, // 20
// The entries with line_num == -1 mark the end of a function: the
// associated offset is one past the last instruction in the
// function. This can correspond to the beginning of the next
// function (as is true for offset 3232); alternately, there can be
// a gap between the end of one function and the start of the next
// (as is true for some others, most obviously from 3236->5764).
//
// Case 1: lookup_key has offset == 10. lower_bound returns
// offsets[0]. Since it's not an exact match and we're
// at the beginning of offsets, we return end() (invalid).
// Case 2: lookup_key has offset 10000. lower_bound returns
// offset[21] (end()). We return end() (invalid).
// Case 3: lookup_key has offset == 3211. lower_bound matches
// offsets[0] exactly, and that's the entry we return.
// Case 4: lookup_key has offset == 3232. lower_bound returns
// offsets[4]. That's an exact match, but indicates
// end-of-function. We check if offsets[5] is also an
// exact match but not end-of-function. It is, so we
// return offsets[5].
// Case 5: lookup_key has offset == 3214. lower_bound returns
// offsets[1]. Since it's not an exact match, we back
// up to the offset that's < lookup_key, offsets[0].
// We note offsets[0] is a valid entry (not end-of-function),
// so that's the entry we return.
// Case 6: lookup_key has offset == 4000. lower_bound returns
// offsets[8]. Since it's not an exact match, we back
// up to offsets[7]. Since offsets[7] indicates
// end-of-function, we know lookup_key is between
// functions, so we return end() (not a valid offset).
// Case 7: lookup_key has offset == 5794. lower_bound returns
// offsets[19]. Since it's not an exact match, we back
// up to offsets[16]. Note we back up to the *first*
// entry with offset 5793, not just offsets[19-1].
// We note offsets[16] is a valid entry, so we return it.
// If offsets[16] had had line_num == -1, we would have
// checked offsets[17]. The reason for this is that
// 16 and 17 can be in an arbitrary order, since we sort
// only by offset and last_line_for_offset. (Note it
// doesn't help to use line_number as a tertiary sort key,
// since sometimes we want the -1 to be first and sometimes
// we want it to be last.)
// This deals with cases (1) and (2).
if ((it == offsets->begin() && offset < it->offset)
|| it == offsets->end())
return offsets->end();
// This deals with cases (3) and (4).
if (offset == it->offset)
{
while (it != offsets->end()
&& it->offset == offset
&& it->line_num == -1)
++it;
if (it == offsets->end() || it->offset != offset)
return offsets->end();
else
return it;
}
// This handles the first part of case (7) -- we back up to the
// *first* entry that has the offset that's behind us.
gold_assert(it != offsets->begin());
std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
--it;
const off_t range_value = it->offset;
while (it != offsets->begin() && (it-1)->offset == range_value)
--it;
// This handles cases (5), (6), and (7): if any entry in the
// equal_range [it, range_end) has a line_num != -1, it's a valid
// match. If not, we're not in a function. The line number we saw
// last for an offset will be sorted first, so it'll get returned if
// it's present.
for (; it != range_end; ++it)
if (it->line_num != -1)
return it;
return offsets->end();
}
// Returns the canonical filename:lineno for the address passed in.
// If other_lines is not NULL, appends the non-canonical lines
// assigned to the same address.
template<int size, bool big_endian>
std::string
Sized_dwarf_line_info<size, big_endian>::do_addr2line(
unsigned int shndx,
off_t offset,
std::vector<std::string>* other_lines)
{
if (this->data_valid_ == false)
return "";
const std::vector<Offset_to_lineno_entry>* offsets;
// If we do not have reloc information, then our input is a .so or
// some similar data structure where all the information is held in
// the offset. In that case, we ignore the input shndx.
if (this->input_is_relobj())
offsets = &this->line_number_map_[shndx];
else
offsets = &this->line_number_map_[-1U];
if (offsets->empty())
return "";
typename std::vector<Offset_to_lineno_entry>::const_iterator it
= offset_to_iterator(offsets, offset);
if (it == offsets->end())
return "";
std::string result = this->format_file_lineno(*it);
gold_debug(DEBUG_LOCATION, "do_addr2line: canonical result: %s",
result.c_str());
if (other_lines != NULL)
{
unsigned int last_file_num = it->file_num;
int last_line_num = it->line_num;
// Return up to 4 more locations from the beginning of the function
// for fuzzy matching.
for (++it; it != offsets->end(); ++it)
{
if (it->offset == offset && it->line_num == -1)
continue; // The end of a previous function.
if (it->line_num == -1)
break; // The end of the current function.
if (it->file_num != last_file_num || it->line_num != last_line_num)
{
other_lines->push_back(this->format_file_lineno(*it));
gold_debug(DEBUG_LOCATION, "do_addr2line: other: %s",
other_lines->back().c_str());
last_file_num = it->file_num;
last_line_num = it->line_num;
}
if (it->offset > offset && other_lines->size() >= 4)
break;
}
}
return result;
}
// Convert the file_num + line_num into a string.
template<int size, bool big_endian>
std::string
Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
const Offset_to_lineno_entry& loc) const
{
std::string ret;
gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
gold_assert(loc.file_num
< static_cast<unsigned int>(this->files_[loc.header_num].size()));
const std::pair<int, std::string>& filename_pair
= this->files_[loc.header_num][loc.file_num];
const std::string& filename = filename_pair.second;
gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
gold_assert(filename_pair.first
< static_cast<int>(this->directories_[loc.header_num].size()));
const std::string& dirname
= this->directories_[loc.header_num][filename_pair.first];
if (!dirname.empty())
{
ret += dirname;
ret += "/";
}
ret += filename;
if (ret.empty())
ret = "(unknown)";
char buffer[64]; // enough to hold a line number
snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
ret += ":";
ret += buffer;
return ret;
}
// Dwarf_line_info routines.
static unsigned int next_generation_count = 0;
struct Addr2line_cache_entry
{
Object* object;
unsigned int shndx;
Dwarf_line_info* dwarf_line_info;
unsigned int generation_count;
unsigned int access_count;
Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
: object(o), shndx(s), dwarf_line_info(d),
generation_count(next_generation_count), access_count(0)
{
if (next_generation_count < (1U << 31))
++next_generation_count;
}
};
// We expect this cache to be small, so don't bother with a hashtable
// or priority queue or anything: just use a simple vector.
static std::vector<Addr2line_cache_entry> addr2line_cache;
std::string
Dwarf_line_info::one_addr2line(Object* object,
unsigned int shndx, off_t offset,
size_t cache_size,
std::vector<std::string>* other_lines)
{
Dwarf_line_info* lineinfo = NULL;
std::vector<Addr2line_cache_entry>::iterator it;
// First, check the cache. If we hit, update the counts.
for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
{
if (it->object == object && it->shndx == shndx)
{
lineinfo = it->dwarf_line_info;
it->generation_count = next_generation_count;
// We cap generation_count at 2^31 -1 to avoid overflow.
if (next_generation_count < (1U << 31))
++next_generation_count;
// We cap access_count at 31 so 2^access_count doesn't overflow
if (it->access_count < 31)
++it->access_count;
break;
}
}
// If we don't hit the cache, create a new object and insert into the
// cache.
if (lineinfo == NULL)
{
switch (parameters->size_and_endianness())
{
#ifdef HAVE_TARGET_32_LITTLE
case Parameters::TARGET_32_LITTLE:
lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
#endif
#ifdef HAVE_TARGET_32_BIG
case Parameters::TARGET_32_BIG:
lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
#endif
#ifdef HAVE_TARGET_64_LITTLE
case Parameters::TARGET_64_LITTLE:
lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
#endif
#ifdef HAVE_TARGET_64_BIG
case Parameters::TARGET_64_BIG:
lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
#endif
default:
gold_unreachable();
}
addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
}
// Now that we have our object, figure out the answer
std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
// Finally, if our cache has grown too big, delete old objects. We
// assume the common (probably only) case is deleting only one object.
// We use a pretty simple scheme to evict: function of LRU and MFU.
while (addr2line_cache.size() > cache_size)
{
unsigned int lowest_score = ~0U;
std::vector<Addr2line_cache_entry>::iterator lowest
= addr2line_cache.end();
for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
{
const unsigned int score = (it->generation_count
+ (1U << it->access_count));
if (score < lowest_score)
{
lowest_score = score;
lowest = it;
}
}
if (lowest != addr2line_cache.end())
{
delete lowest->dwarf_line_info;
addr2line_cache.erase(lowest);
}
}
return retval;
}
void
Dwarf_line_info::clear_addr2line_cache()
{
for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
it != addr2line_cache.end();
++it)
delete it->dwarf_line_info;
addr2line_cache.clear();
}
#ifdef HAVE_TARGET_32_LITTLE
template
class Sized_dwarf_line_info<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Sized_dwarf_line_info<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Sized_dwarf_line_info<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Sized_dwarf_line_info<64, true>;
#endif
} // End namespace gold.