1199 lines
33 KiB
C++
1199 lines
33 KiB
C++
// ehframe.cc -- handle exception frame sections for gold
|
|
|
|
// Copyright 2006, 2007 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 <cstring>
|
|
#include <algorithm>
|
|
|
|
#include "elfcpp.h"
|
|
#include "dwarf.h"
|
|
#include "symtab.h"
|
|
#include "reloc.h"
|
|
#include "ehframe.h"
|
|
|
|
namespace gold
|
|
{
|
|
|
|
// This file handles generation of the exception frame header that
|
|
// gcc's runtime support libraries use to find unwind information at
|
|
// runtime. This file also handles discarding duplicate exception
|
|
// frame information.
|
|
|
|
// The exception frame header starts with four bytes:
|
|
|
|
// 0: The version number, currently 1.
|
|
|
|
// 1: The encoding of the pointer to the exception frames. This can
|
|
// be any DWARF unwind encoding (DW_EH_PE_*). It is normally a 4
|
|
// byte PC relative offset (DW_EH_PE_pcrel | DW_EH_PE_sdata4).
|
|
|
|
// 2: The encoding of the count of the number of FDE pointers in the
|
|
// lookup table. This can be any DWARF unwind encoding, and in
|
|
// particular can be DW_EH_PE_omit if the count is omitted. It is
|
|
// normally a 4 byte unsigned count (DW_EH_PE_udata4).
|
|
|
|
// 3: The encoding of the lookup table entries. Currently gcc's
|
|
// libraries will only support DW_EH_PE_datarel | DW_EH_PE_sdata4,
|
|
// which means that the values are 4 byte offsets from the start of
|
|
// the table.
|
|
|
|
// The exception frame header is followed by a pointer to the contents
|
|
// of the exception frame section (.eh_frame). This pointer is
|
|
// encoded as specified in the byte at offset 1 of the header (i.e.,
|
|
// it is normally a 4 byte PC relative offset).
|
|
|
|
// If there is a lookup table, this is followed by the count of the
|
|
// number of FDE pointers, encoded as specified in the byte at offset
|
|
// 2 of the header (i.e., normally a 4 byte unsigned integer).
|
|
|
|
// This is followed by the table, which should start at an 4-byte
|
|
// aligned address in memory. Each entry in the table is 8 bytes.
|
|
// Each entry represents an FDE. The first four bytes of each entry
|
|
// are an offset to the starting PC for the FDE. The last four bytes
|
|
// of each entry are an offset to the FDE data. The offsets are from
|
|
// the start of the exception frame header information. The entries
|
|
// are in sorted order by starting PC.
|
|
|
|
const int eh_frame_hdr_size = 4;
|
|
|
|
// Construct the exception frame header.
|
|
|
|
Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section,
|
|
const Eh_frame* eh_frame_data)
|
|
: Output_section_data(4),
|
|
eh_frame_section_(eh_frame_section),
|
|
eh_frame_data_(eh_frame_data),
|
|
fde_offsets_(),
|
|
any_unrecognized_eh_frame_sections_(false)
|
|
{
|
|
}
|
|
|
|
// Set the size of the exception frame header.
|
|
|
|
void
|
|
Eh_frame_hdr::set_final_data_size()
|
|
{
|
|
unsigned int data_size = eh_frame_hdr_size + 4;
|
|
if (!this->any_unrecognized_eh_frame_sections_)
|
|
{
|
|
unsigned int fde_count = this->eh_frame_data_->fde_count();
|
|
if (fde_count != 0)
|
|
data_size += 4 + 8 * fde_count;
|
|
this->fde_offsets_.reserve(fde_count);
|
|
}
|
|
this->set_data_size(data_size);
|
|
}
|
|
|
|
// Write the data to the flie.
|
|
|
|
void
|
|
Eh_frame_hdr::do_write(Output_file* of)
|
|
{
|
|
if (parameters->get_size() == 32)
|
|
{
|
|
if (!parameters->is_big_endian())
|
|
{
|
|
#ifdef HAVE_TARGET_32_LITTLE
|
|
this->do_sized_write<32, false>(of);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
#ifdef HAVE_TARGET_32_BIG
|
|
this->do_sized_write<32, true>(of);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
}
|
|
else if (parameters->get_size() == 64)
|
|
{
|
|
if (!parameters->is_big_endian())
|
|
{
|
|
#ifdef HAVE_TARGET_64_LITTLE
|
|
this->do_sized_write<64, false>(of);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
#ifdef HAVE_TARGET_64_BIG
|
|
this->do_sized_write<64, true>(of);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
}
|
|
else
|
|
gold_unreachable();
|
|
}
|
|
|
|
// Write the data to the file with the right endianness.
|
|
|
|
template<int size, bool big_endian>
|
|
void
|
|
Eh_frame_hdr::do_sized_write(Output_file* of)
|
|
{
|
|
const off_t off = this->offset();
|
|
const off_t oview_size = this->data_size();
|
|
unsigned char* const oview = of->get_output_view(off, oview_size);
|
|
|
|
// Version number.
|
|
oview[0] = 1;
|
|
|
|
// Write out a 4 byte PC relative offset to the address of the
|
|
// .eh_frame section.
|
|
oview[1] = elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4;
|
|
uint64_t eh_frame_address = this->eh_frame_section_->address();
|
|
uint64_t eh_frame_hdr_address = this->address();
|
|
uint64_t eh_frame_offset = (eh_frame_address -
|
|
(eh_frame_hdr_address + 4));
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + 4, eh_frame_offset);
|
|
|
|
if (this->any_unrecognized_eh_frame_sections_
|
|
|| this->fde_offsets_.empty())
|
|
{
|
|
// There are no FDEs, or we didn't recognize the format of the
|
|
// some of the .eh_frame sections, so we can't write out the
|
|
// sorted table.
|
|
oview[2] = elfcpp::DW_EH_PE_omit;
|
|
oview[3] = elfcpp::DW_EH_PE_omit;
|
|
|
|
gold_assert(oview_size == 8);
|
|
}
|
|
else
|
|
{
|
|
oview[2] = elfcpp::DW_EH_PE_udata4;
|
|
oview[3] = elfcpp::DW_EH_PE_datarel | elfcpp::DW_EH_PE_sdata4;
|
|
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + 8,
|
|
this->fde_offsets_.size());
|
|
|
|
// We have the offsets of the FDEs in the .eh_frame section. We
|
|
// couldn't easily get the PC values before, as they depend on
|
|
// relocations which are, of course, target specific. This code
|
|
// is run after all those relocations have been applied to the
|
|
// output file. Here we read the output file again to find the
|
|
// PC values. Then we sort the list and write it out.
|
|
|
|
Fde_addresses<size> fde_addresses(this->fde_offsets_.size());
|
|
this->get_fde_addresses<size, big_endian>(of, &this->fde_offsets_,
|
|
&fde_addresses);
|
|
|
|
std::sort(fde_addresses.begin(), fde_addresses.end(),
|
|
Fde_address_compare<size>());
|
|
|
|
typename elfcpp::Elf_types<size>::Elf_Addr output_address;
|
|
output_address = this->address();
|
|
|
|
unsigned char* pfde = oview + 12;
|
|
for (typename Fde_addresses<size>::iterator p = fde_addresses.begin();
|
|
p != fde_addresses.end();
|
|
++p)
|
|
{
|
|
elfcpp::Swap<32, big_endian>::writeval(pfde,
|
|
p->first - output_address);
|
|
elfcpp::Swap<32, big_endian>::writeval(pfde + 4,
|
|
p->second - output_address);
|
|
pfde += 8;
|
|
}
|
|
|
|
gold_assert(pfde - oview == oview_size);
|
|
}
|
|
|
|
of->write_output_view(off, oview_size, oview);
|
|
}
|
|
|
|
// Given the offset FDE_OFFSET of an FDE in the .eh_frame section, and
|
|
// the contents of the .eh_frame section EH_FRAME_CONTENTS, where the
|
|
// FDE's encoding is FDE_ENCODING, return the output address of the
|
|
// FDE's PC.
|
|
|
|
template<int size, bool big_endian>
|
|
typename elfcpp::Elf_types<size>::Elf_Addr
|
|
Eh_frame_hdr::get_fde_pc(
|
|
typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address,
|
|
const unsigned char* eh_frame_contents,
|
|
section_offset_type fde_offset,
|
|
unsigned char fde_encoding)
|
|
{
|
|
// The FDE starts with a 4 byte length and a 4 byte offset to the
|
|
// CIE. The PC follows.
|
|
const unsigned char* p = eh_frame_contents + fde_offset + 8;
|
|
|
|
typename elfcpp::Elf_types<size>::Elf_Addr pc;
|
|
bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0;
|
|
int pc_size = fde_encoding & 7;
|
|
if (pc_size == elfcpp::DW_EH_PE_absptr)
|
|
{
|
|
if (size == 32)
|
|
pc_size = elfcpp::DW_EH_PE_udata4;
|
|
else if (size == 64)
|
|
pc_size = elfcpp::DW_EH_PE_udata8;
|
|
else
|
|
gold_unreachable();
|
|
}
|
|
|
|
switch (pc_size)
|
|
{
|
|
case elfcpp::DW_EH_PE_udata2:
|
|
pc = elfcpp::Swap<16, big_endian>::readval(p);
|
|
if (is_signed)
|
|
pc = (pc ^ 0x8000) - 0x8000;
|
|
break;
|
|
|
|
case elfcpp::DW_EH_PE_udata4:
|
|
pc = elfcpp::Swap<32, big_endian>::readval(p);
|
|
if (size > 32 && is_signed)
|
|
pc = (pc ^ 0x80000000) - 0x80000000;
|
|
break;
|
|
|
|
case elfcpp::DW_EH_PE_udata8:
|
|
gold_assert(size == 64);
|
|
pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p);
|
|
break;
|
|
|
|
default:
|
|
// All other cases were rejected in Eh_frame::read_cie.
|
|
gold_unreachable();
|
|
}
|
|
|
|
switch (fde_encoding & 0xf0)
|
|
{
|
|
case 0:
|
|
break;
|
|
|
|
case elfcpp::DW_EH_PE_pcrel:
|
|
pc += eh_frame_address + fde_offset + 8;
|
|
break;
|
|
|
|
default:
|
|
// If other cases arise, then we have to handle them, or we have
|
|
// to reject them by returning false in Eh_frame::read_cie.
|
|
gold_unreachable();
|
|
}
|
|
|
|
return pc;
|
|
}
|
|
|
|
// Given an array of FDE offsets in the .eh_frame section, return an
|
|
// array of offsets from the exception frame header to the FDE's
|
|
// output PC and to the output address of the FDE itself. We get the
|
|
// FDE's PC by actually looking in the .eh_frame section we just wrote
|
|
// to the output file.
|
|
|
|
template<int size, bool big_endian>
|
|
void
|
|
Eh_frame_hdr::get_fde_addresses(Output_file* of,
|
|
const Fde_offsets* fde_offsets,
|
|
Fde_addresses<size>* fde_addresses)
|
|
{
|
|
typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address;
|
|
eh_frame_address = this->eh_frame_section_->address();
|
|
off_t eh_frame_offset = this->eh_frame_section_->offset();
|
|
off_t eh_frame_size = this->eh_frame_section_->data_size();
|
|
const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset,
|
|
eh_frame_size);
|
|
|
|
for (Fde_offsets::const_iterator p = fde_offsets->begin();
|
|
p != fde_offsets->end();
|
|
++p)
|
|
{
|
|
typename elfcpp::Elf_types<size>::Elf_Addr fde_pc;
|
|
fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_address,
|
|
eh_frame_contents,
|
|
p->first, p->second);
|
|
fde_addresses->push_back(fde_pc, eh_frame_address + p->first);
|
|
}
|
|
|
|
of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents);
|
|
}
|
|
|
|
// Class Fde.
|
|
|
|
// Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the
|
|
// offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the
|
|
// CIE. ADDRALIGN is the required alignment. Record the FDE pc for
|
|
// EH_FRAME_HDR. Return the new offset.
|
|
|
|
template<int size, bool big_endian>
|
|
section_offset_type
|
|
Fde::write(unsigned char* oview, section_offset_type offset,
|
|
unsigned int addralign, section_offset_type cie_offset,
|
|
unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr)
|
|
{
|
|
gold_assert((offset & (addralign - 1)) == 0);
|
|
|
|
size_t length = this->contents_.length();
|
|
|
|
// We add 8 when getting the aligned length to account for the
|
|
// length word and the CIE offset.
|
|
size_t aligned_full_length = align_address(length + 8, addralign);
|
|
|
|
// Write the length of the FDE as a 32-bit word. The length word
|
|
// does not include the four bytes of the length word itself, but it
|
|
// does include the offset to the CIE.
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + offset,
|
|
aligned_full_length - 4);
|
|
|
|
// Write the offset to the CIE as a 32-bit word. This is the
|
|
// difference between the address of the offset word itself and the
|
|
// CIE address.
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4,
|
|
offset + 4 - cie_offset);
|
|
|
|
// Copy the rest of the FDE. Note that this is run before
|
|
// relocation processing is done on this section, so the relocations
|
|
// will later be applied to the FDE data.
|
|
memcpy(oview + offset + 8, this->contents_.data(), length);
|
|
|
|
if (aligned_full_length > length + 8)
|
|
memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
|
|
|
|
// Tell the exception frame header about this FDE.
|
|
if (eh_frame_hdr != NULL)
|
|
eh_frame_hdr->record_fde(offset, fde_encoding);
|
|
|
|
return offset + aligned_full_length;
|
|
}
|
|
|
|
// Class Cie.
|
|
|
|
// Destructor.
|
|
|
|
Cie::~Cie()
|
|
{
|
|
for (std::vector<Fde*>::iterator p = this->fdes_.begin();
|
|
p != this->fdes_.end();
|
|
++p)
|
|
delete *p;
|
|
}
|
|
|
|
// Set the output offset of a CIE. Return the new output offset.
|
|
|
|
section_offset_type
|
|
Cie::set_output_offset(section_offset_type output_offset,
|
|
unsigned int addralign,
|
|
Merge_map* merge_map)
|
|
{
|
|
size_t length = this->contents_.length();
|
|
|
|
// Add 4 for length and 4 for zero CIE identifier tag.
|
|
length += 8;
|
|
|
|
merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_,
|
|
length, output_offset);
|
|
|
|
length = align_address(length, addralign);
|
|
|
|
for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
|
|
p != this->fdes_.end();
|
|
++p)
|
|
{
|
|
(*p)->add_mapping(output_offset + length, merge_map);
|
|
|
|
size_t fde_length = (*p)->length();
|
|
fde_length = align_address(fde_length, addralign);
|
|
length += fde_length;
|
|
}
|
|
|
|
return output_offset + length;
|
|
}
|
|
|
|
// Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE
|
|
// recording. Round up the bytes to ADDRALIGN. Return the new
|
|
// offset.
|
|
|
|
template<int size, bool big_endian>
|
|
section_offset_type
|
|
Cie::write(unsigned char* oview, section_offset_type offset,
|
|
unsigned int addralign, Eh_frame_hdr* eh_frame_hdr)
|
|
{
|
|
gold_assert((offset & (addralign - 1)) == 0);
|
|
|
|
section_offset_type cie_offset = offset;
|
|
|
|
size_t length = this->contents_.length();
|
|
|
|
// We add 8 when getting the aligned length to account for the
|
|
// length word and the CIE tag.
|
|
size_t aligned_full_length = align_address(length + 8, addralign);
|
|
|
|
// Write the length of the CIE as a 32-bit word. The length word
|
|
// does not include the four bytes of the length word itself.
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + offset,
|
|
aligned_full_length - 4);
|
|
|
|
// Write the tag which marks this as a CIE: a 32-bit zero.
|
|
elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0);
|
|
|
|
// Write out the CIE data.
|
|
memcpy(oview + offset + 8, this->contents_.data(), length);
|
|
|
|
if (aligned_full_length > length + 8)
|
|
memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
|
|
|
|
offset += aligned_full_length;
|
|
|
|
// Write out the associated FDEs.
|
|
unsigned char fde_encoding = this->fde_encoding_;
|
|
for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
|
|
p != this->fdes_.end();
|
|
++p)
|
|
offset = (*p)->write<size, big_endian>(oview, offset, addralign,
|
|
cie_offset, fde_encoding,
|
|
eh_frame_hdr);
|
|
|
|
return offset;
|
|
}
|
|
|
|
// We track all the CIEs we see, and merge them when possible. This
|
|
// works because each FDE holds an offset to the relevant CIE: we
|
|
// rewrite the FDEs to point to the merged CIE. This is worthwhile
|
|
// because in a typical C++ program many FDEs in many different object
|
|
// files will use the same CIE.
|
|
|
|
// An equality operator for Cie.
|
|
|
|
bool
|
|
operator==(const Cie& cie1, const Cie& cie2)
|
|
{
|
|
return (cie1.personality_name_ == cie2.personality_name_
|
|
&& cie1.contents_ == cie2.contents_);
|
|
}
|
|
|
|
// A less-than operator for Cie.
|
|
|
|
bool
|
|
operator<(const Cie& cie1, const Cie& cie2)
|
|
{
|
|
if (cie1.personality_name_ != cie2.personality_name_)
|
|
return cie1.personality_name_ < cie2.personality_name_;
|
|
return cie1.contents_ < cie2.contents_;
|
|
}
|
|
|
|
// Class Eh_frame.
|
|
|
|
Eh_frame::Eh_frame()
|
|
: Output_section_data(Output_data::default_alignment()),
|
|
eh_frame_hdr_(NULL),
|
|
cie_offsets_(),
|
|
unmergeable_cie_offsets_(),
|
|
merge_map_()
|
|
{
|
|
}
|
|
|
|
// Skip an LEB128, updating *PP to point to the next character.
|
|
// Return false if we ran off the end of the string.
|
|
|
|
bool
|
|
Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend)
|
|
{
|
|
const unsigned char* p;
|
|
for (p = *pp; p < pend; ++p)
|
|
{
|
|
if ((*p & 0x80) == 0)
|
|
{
|
|
*pp = p + 1;
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Add input section SHNDX in OBJECT to an exception frame section.
|
|
// SYMBOLS is the contents of the symbol table section (size
|
|
// SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size
|
|
// SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation
|
|
// section applying to SHNDX, or 0 if none, or -1U if more than one.
|
|
// RELOC_TYPE is the type of the reloc section if there is one, either
|
|
// SHT_REL or SHT_RELA. We try to parse the input exception frame
|
|
// data into our data structures. If we can't do it, we return false
|
|
// to mean that the section should be handled as a normal input
|
|
// section.
|
|
|
|
template<int size, bool big_endian>
|
|
bool
|
|
Eh_frame::add_ehframe_input_section(
|
|
Sized_relobj<size, big_endian>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type)
|
|
{
|
|
// Get the section contents.
|
|
section_size_type contents_len;
|
|
const unsigned char* pcontents = object->section_contents(shndx,
|
|
&contents_len,
|
|
false);
|
|
if (contents_len == 0)
|
|
return false;
|
|
|
|
// If this is the marker section for the end of the data, then
|
|
// return false to force it to be handled as an ordinary input
|
|
// section. If we don't do this, we won't correctly handle the case
|
|
// of unrecognized .eh_frame sections.
|
|
if (contents_len == 4
|
|
&& elfcpp::Swap<32, big_endian>::readval(pcontents) == 0)
|
|
return false;
|
|
|
|
New_cies new_cies;
|
|
if (!this->do_add_ehframe_input_section(object, symbols, symbols_size,
|
|
symbol_names, symbol_names_size,
|
|
shndx, reloc_shndx,
|
|
reloc_type, pcontents,
|
|
contents_len, &new_cies))
|
|
{
|
|
this->eh_frame_hdr_->found_unrecognized_eh_frame_section();
|
|
|
|
for (New_cies::iterator p = new_cies.begin();
|
|
p != new_cies.end();
|
|
++p)
|
|
delete p->first;
|
|
|
|
return false;
|
|
}
|
|
|
|
// Now that we know we are using this section, record any new CIEs
|
|
// that we found.
|
|
for (New_cies::const_iterator p = new_cies.begin();
|
|
p != new_cies.end();
|
|
++p)
|
|
{
|
|
if (p->second)
|
|
this->cie_offsets_.insert(p->first);
|
|
else
|
|
this->unmergeable_cie_offsets_.push_back(p->first);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
// The bulk of the implementation of add_ehframe_input_section.
|
|
|
|
template<int size, bool big_endian>
|
|
bool
|
|
Eh_frame::do_add_ehframe_input_section(
|
|
Sized_relobj<size, big_endian>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type,
|
|
const unsigned char* pcontents,
|
|
section_size_type contents_len,
|
|
New_cies* new_cies)
|
|
{
|
|
typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
|
|
Track_relocs<size, big_endian> relocs;
|
|
|
|
const unsigned char* p = pcontents;
|
|
const unsigned char* pend = p + contents_len;
|
|
|
|
// Get the contents of the reloc section if any.
|
|
if (!relocs.initialize(object, reloc_shndx, reloc_type))
|
|
return false;
|
|
|
|
// Keep track of which CIEs are at which offsets.
|
|
Offsets_to_cie cies;
|
|
|
|
while (p < pend)
|
|
{
|
|
if (pend - p < 4)
|
|
return false;
|
|
|
|
// There shouldn't be any relocations here.
|
|
if (relocs.advance(p + 4 - pcontents) > 0)
|
|
return false;
|
|
|
|
unsigned int len = elfcpp::Swap<32, big_endian>::readval(p);
|
|
p += 4;
|
|
if (len == 0)
|
|
{
|
|
// We should only find a zero-length entry at the end of the
|
|
// section.
|
|
if (p < pend)
|
|
return false;
|
|
break;
|
|
}
|
|
// We don't support a 64-bit .eh_frame.
|
|
if (len == 0xffffffff)
|
|
return false;
|
|
if (static_cast<unsigned int>(pend - p) < len)
|
|
return false;
|
|
|
|
const unsigned char* const pentend = p + len;
|
|
|
|
if (pend - p < 4)
|
|
return false;
|
|
if (relocs.advance(p + 4 - pcontents) > 0)
|
|
return false;
|
|
|
|
unsigned int id = elfcpp::Swap<32, big_endian>::readval(p);
|
|
p += 4;
|
|
|
|
if (id == 0)
|
|
{
|
|
// CIE.
|
|
if (!this->read_cie(object, shndx, symbols, symbols_size,
|
|
symbol_names, symbol_names_size,
|
|
pcontents, p, pentend, &relocs, &cies,
|
|
new_cies))
|
|
return false;
|
|
}
|
|
else
|
|
{
|
|
// FDE.
|
|
if (!this->read_fde(object, shndx, symbols, symbols_size,
|
|
pcontents, id, p, pentend, &relocs, &cies))
|
|
return false;
|
|
}
|
|
|
|
p = pentend;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
// Read a CIE. Return false if we can't parse the information.
|
|
|
|
template<int size, bool big_endian>
|
|
bool
|
|
Eh_frame::read_cie(Sized_relobj<size, big_endian>* object,
|
|
unsigned int shndx,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
const unsigned char* pcontents,
|
|
const unsigned char* pcie,
|
|
const unsigned char *pcieend,
|
|
Track_relocs<size, big_endian>* relocs,
|
|
Offsets_to_cie* cies,
|
|
New_cies* new_cies)
|
|
{
|
|
bool mergeable = true;
|
|
|
|
// We need to find the personality routine if there is one, since we
|
|
// can only merge CIEs which use the same routine. We also need to
|
|
// find the FDE encoding if there is one, so that we can read the PC
|
|
// from the FDE.
|
|
|
|
const unsigned char* p = pcie;
|
|
|
|
if (pcieend - p < 1)
|
|
return false;
|
|
unsigned char version = *p++;
|
|
if (version != 1 && version != 3)
|
|
return false;
|
|
|
|
const unsigned char* paug = p;
|
|
const void* paugendv = memchr(p, '\0', pcieend - p);
|
|
const unsigned char* paugend = static_cast<const unsigned char*>(paugendv);
|
|
if (paugend == NULL)
|
|
return false;
|
|
p = paugend + 1;
|
|
|
|
if (paug[0] == 'e' && paug[1] == 'h')
|
|
{
|
|
// This is a CIE from gcc before version 3.0. We can't merge
|
|
// these. We can still read the FDEs.
|
|
mergeable = false;
|
|
paug += 2;
|
|
if (*paug != '\0')
|
|
return false;
|
|
if (pcieend - p < size / 8)
|
|
return false;
|
|
p += size / 8;
|
|
}
|
|
|
|
// Skip the code alignment.
|
|
if (!skip_leb128(&p, pcieend))
|
|
return false;
|
|
|
|
// Skip the data alignment.
|
|
if (!skip_leb128(&p, pcieend))
|
|
return false;
|
|
|
|
// Skip the return column.
|
|
if (version == 1)
|
|
{
|
|
if (pcieend - p < 1)
|
|
return false;
|
|
++p;
|
|
}
|
|
else
|
|
{
|
|
if (!skip_leb128(&p, pcieend))
|
|
return false;
|
|
}
|
|
|
|
if (*paug == 'z')
|
|
{
|
|
++paug;
|
|
// Skip the augmentation size.
|
|
if (!skip_leb128(&p, pcieend))
|
|
return false;
|
|
}
|
|
|
|
unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr;
|
|
int per_offset = -1;
|
|
while (*paug != '\0')
|
|
{
|
|
switch (*paug)
|
|
{
|
|
case 'L': // LSDA encoding.
|
|
if (pcieend - p < 1)
|
|
return false;
|
|
++p;
|
|
break;
|
|
|
|
case 'R': // FDE encoding.
|
|
if (pcieend - p < 1)
|
|
return false;
|
|
fde_encoding = *p;
|
|
switch (fde_encoding & 7)
|
|
{
|
|
case elfcpp::DW_EH_PE_absptr:
|
|
case elfcpp::DW_EH_PE_udata2:
|
|
case elfcpp::DW_EH_PE_udata4:
|
|
case elfcpp::DW_EH_PE_udata8:
|
|
break;
|
|
default:
|
|
// We don't expect to see any other cases here, and
|
|
// we're not prepared to handle them.
|
|
return false;
|
|
}
|
|
++p;
|
|
break;
|
|
|
|
case 'S':
|
|
break;
|
|
|
|
case 'P':
|
|
// Personality encoding.
|
|
{
|
|
if (pcieend - p < 1)
|
|
return false;
|
|
unsigned char per_encoding = *p;
|
|
++p;
|
|
|
|
if ((per_encoding & 0x60) == 0x60)
|
|
return false;
|
|
unsigned int per_width;
|
|
switch (per_encoding & 7)
|
|
{
|
|
case elfcpp::DW_EH_PE_udata2:
|
|
per_width = 2;
|
|
break;
|
|
case elfcpp::DW_EH_PE_udata4:
|
|
per_width = 4;
|
|
break;
|
|
case elfcpp::DW_EH_PE_udata8:
|
|
per_width = 8;
|
|
break;
|
|
case elfcpp::DW_EH_PE_absptr:
|
|
per_width = size / 8;
|
|
break;
|
|
default:
|
|
return false;
|
|
}
|
|
|
|
if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned)
|
|
{
|
|
unsigned int len = p - pcie;
|
|
len += per_width - 1;
|
|
len &= ~ (per_width - 1);
|
|
if (static_cast<unsigned int>(pcieend - p) < len)
|
|
return false;
|
|
p += len;
|
|
}
|
|
|
|
per_offset = p - pcontents;
|
|
|
|
if (static_cast<unsigned int>(pcieend - p) < per_width)
|
|
return false;
|
|
p += per_width;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
|
|
++paug;
|
|
}
|
|
|
|
const char* personality_name = "";
|
|
if (per_offset != -1)
|
|
{
|
|
if (relocs->advance(per_offset) > 0)
|
|
return false;
|
|
if (relocs->next_offset() != per_offset)
|
|
return false;
|
|
|
|
unsigned int personality_symndx = relocs->next_symndx();
|
|
if (personality_symndx == -1U)
|
|
return false;
|
|
|
|
if (personality_symndx < object->local_symbol_count())
|
|
{
|
|
// We can only merge this CIE if the personality routine is
|
|
// a global symbol. We can still read the FDEs.
|
|
mergeable = false;
|
|
}
|
|
else
|
|
{
|
|
const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
|
|
if (personality_symndx >= symbols_size / sym_size)
|
|
return false;
|
|
elfcpp::Sym<size, big_endian> sym(symbols
|
|
+ (personality_symndx * sym_size));
|
|
unsigned int name_offset = sym.get_st_name();
|
|
if (name_offset >= symbol_names_size)
|
|
return false;
|
|
personality_name = (reinterpret_cast<const char*>(symbol_names)
|
|
+ name_offset);
|
|
}
|
|
|
|
int r = relocs->advance(per_offset + 1);
|
|
gold_assert(r == 1);
|
|
}
|
|
|
|
if (relocs->advance(pcieend - pcontents) > 0)
|
|
return false;
|
|
|
|
Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding,
|
|
personality_name, pcie, pcieend - pcie);
|
|
Cie* cie_pointer = NULL;
|
|
if (mergeable)
|
|
{
|
|
Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
|
|
if (find_cie != this->cie_offsets_.end())
|
|
cie_pointer = *find_cie;
|
|
else
|
|
{
|
|
// See if we already saw this CIE in this object file.
|
|
for (New_cies::const_iterator pc = new_cies->begin();
|
|
pc != new_cies->end();
|
|
++pc)
|
|
{
|
|
if (*(pc->first) == cie)
|
|
{
|
|
cie_pointer = pc->first;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (cie_pointer == NULL)
|
|
{
|
|
cie_pointer = new Cie(cie);
|
|
new_cies->push_back(std::make_pair(cie_pointer, mergeable));
|
|
}
|
|
else
|
|
{
|
|
// We are deleting this CIE. Record that in our mapping from
|
|
// input sections to the output section. At this point we don't
|
|
// know for sure that we are doing a special mapping for this
|
|
// input section, but that's OK--if we don't do a special
|
|
// mapping, nobody will ever ask for the mapping we add here.
|
|
this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents,
|
|
pcieend - (pcie - 8), -1);
|
|
}
|
|
|
|
// Record this CIE plus the offset in the input section.
|
|
cies->insert(std::make_pair(pcie - pcontents, cie_pointer));
|
|
|
|
return true;
|
|
}
|
|
|
|
// Read an FDE. Return false if we can't parse the information.
|
|
|
|
template<int size, bool big_endian>
|
|
bool
|
|
Eh_frame::read_fde(Sized_relobj<size, big_endian>* object,
|
|
unsigned int shndx,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* pcontents,
|
|
unsigned int offset,
|
|
const unsigned char* pfde,
|
|
const unsigned char *pfdeend,
|
|
Track_relocs<size, big_endian>* relocs,
|
|
Offsets_to_cie* cies)
|
|
{
|
|
// OFFSET is the distance between the 4 bytes before PFDE to the
|
|
// start of the CIE. The offset we recorded for the CIE is 8 bytes
|
|
// after the start of the CIE--after the length and the zero tag.
|
|
unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8;
|
|
Offsets_to_cie::const_iterator pcie = cies->find(cie_offset);
|
|
if (pcie == cies->end())
|
|
return false;
|
|
Cie* cie = pcie->second;
|
|
|
|
// The FDE should start with a reloc to the start of the code which
|
|
// it describes.
|
|
if (relocs->advance(pfde - pcontents) > 0)
|
|
return false;
|
|
|
|
if (relocs->next_offset() != pfde - pcontents)
|
|
return false;
|
|
|
|
unsigned int symndx = relocs->next_symndx();
|
|
if (symndx == -1U)
|
|
return false;
|
|
|
|
// There can be another reloc in the FDE, if the CIE specifies an
|
|
// LSDA (language specific data area). We currently don't care. We
|
|
// will care later if we want to optimize the LSDA from an absolute
|
|
// pointer to a PC relative offset when generating a shared library.
|
|
relocs->advance(pfdeend - pcontents);
|
|
|
|
unsigned int fde_shndx;
|
|
const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
|
|
if (symndx >= symbols_size / sym_size)
|
|
return false;
|
|
elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size);
|
|
fde_shndx = sym.get_st_shndx();
|
|
|
|
if (fde_shndx != elfcpp::SHN_UNDEF
|
|
&& fde_shndx < object->shnum()
|
|
&& !object->is_section_included(fde_shndx))
|
|
{
|
|
// This FDE applies to a section which we are discarding. We
|
|
// can discard this FDE.
|
|
this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents,
|
|
pfdeend - (pfde - 8), -1);
|
|
return true;
|
|
}
|
|
|
|
cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents,
|
|
pfde, pfdeend - pfde));
|
|
|
|
return true;
|
|
}
|
|
|
|
// Return the number of FDEs.
|
|
|
|
unsigned int
|
|
Eh_frame::fde_count() const
|
|
{
|
|
unsigned int ret = 0;
|
|
for (Unmergeable_cie_offsets::const_iterator p =
|
|
this->unmergeable_cie_offsets_.begin();
|
|
p != this->unmergeable_cie_offsets_.end();
|
|
++p)
|
|
ret += (*p)->fde_count();
|
|
for (Cie_offsets::const_iterator p = this->cie_offsets_.begin();
|
|
p != this->cie_offsets_.end();
|
|
++p)
|
|
ret += (*p)->fde_count();
|
|
return ret;
|
|
}
|
|
|
|
// Set the final data size.
|
|
|
|
void
|
|
Eh_frame::set_final_data_size()
|
|
{
|
|
section_offset_type output_offset = 0;
|
|
|
|
for (Unmergeable_cie_offsets::iterator p =
|
|
this->unmergeable_cie_offsets_.begin();
|
|
p != this->unmergeable_cie_offsets_.end();
|
|
++p)
|
|
output_offset = (*p)->set_output_offset(output_offset,
|
|
this->addralign(),
|
|
&this->merge_map_);
|
|
|
|
for (Cie_offsets::iterator p = this->cie_offsets_.begin();
|
|
p != this->cie_offsets_.end();
|
|
++p)
|
|
output_offset = (*p)->set_output_offset(output_offset,
|
|
this->addralign(),
|
|
&this->merge_map_);
|
|
|
|
gold_assert((output_offset & (this->addralign() - 1)) == 0);
|
|
this->set_data_size(output_offset);
|
|
}
|
|
|
|
// Return an output offset for an input offset.
|
|
|
|
bool
|
|
Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx,
|
|
section_offset_type offset,
|
|
section_offset_type* poutput) const
|
|
{
|
|
return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
|
|
}
|
|
|
|
// Return whether this is the merge section for an input section.
|
|
|
|
bool
|
|
Eh_frame::do_is_merge_section_for(const Relobj* object,
|
|
unsigned int shndx) const
|
|
{
|
|
return this->merge_map_.is_merge_section_for(object, shndx);
|
|
}
|
|
|
|
// Write the data to the output file.
|
|
|
|
void
|
|
Eh_frame::do_write(Output_file* of)
|
|
{
|
|
const off_t offset = this->offset();
|
|
const off_t oview_size = this->data_size();
|
|
unsigned char* const oview = of->get_output_view(offset, oview_size);
|
|
|
|
if (parameters->get_size() == 32)
|
|
{
|
|
if (!parameters->is_big_endian())
|
|
{
|
|
#ifdef HAVE_TARGET_32_LITTLE
|
|
this->do_sized_write<32, false>(oview);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
#ifdef HAVE_TARGET_32_BIG
|
|
this->do_sized_write<32, true>(oview);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
}
|
|
else if (parameters->get_size() == 64)
|
|
{
|
|
if (!parameters->is_big_endian())
|
|
{
|
|
#ifdef HAVE_TARGET_64_LITTLE
|
|
this->do_sized_write<64, false>(oview);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
#ifdef HAVE_TARGET_64_BIG
|
|
this->do_sized_write<64, true>(oview);
|
|
#else
|
|
gold_unreachable();
|
|
#endif
|
|
}
|
|
}
|
|
else
|
|
gold_unreachable();
|
|
|
|
of->write_output_view(offset, oview_size, oview);
|
|
}
|
|
|
|
// Write the data to the output file--template version.
|
|
|
|
template<int size, bool big_endian>
|
|
void
|
|
Eh_frame::do_sized_write(unsigned char* oview)
|
|
{
|
|
unsigned int addralign = this->addralign();
|
|
section_offset_type o = 0;
|
|
for (Unmergeable_cie_offsets::iterator p =
|
|
this->unmergeable_cie_offsets_.begin();
|
|
p != this->unmergeable_cie_offsets_.end();
|
|
++p)
|
|
o = (*p)->write<size, big_endian>(oview, o, addralign,
|
|
this->eh_frame_hdr_);
|
|
for (Cie_offsets::iterator p = this->cie_offsets_.begin();
|
|
p != this->cie_offsets_.end();
|
|
++p)
|
|
o = (*p)->write<size, big_endian>(oview, o, addralign,
|
|
this->eh_frame_hdr_);
|
|
}
|
|
|
|
#ifdef HAVE_TARGET_32_LITTLE
|
|
template
|
|
bool
|
|
Eh_frame::add_ehframe_input_section<32, false>(
|
|
Sized_relobj<32, false>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type);
|
|
#endif
|
|
|
|
#ifdef HAVE_TARGET_32_BIG
|
|
template
|
|
bool
|
|
Eh_frame::add_ehframe_input_section<32, true>(
|
|
Sized_relobj<32, true>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type);
|
|
#endif
|
|
|
|
#ifdef HAVE_TARGET_64_LITTLE
|
|
template
|
|
bool
|
|
Eh_frame::add_ehframe_input_section<64, false>(
|
|
Sized_relobj<64, false>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type);
|
|
#endif
|
|
|
|
#ifdef HAVE_TARGET_64_BIG
|
|
template
|
|
bool
|
|
Eh_frame::add_ehframe_input_section<64, true>(
|
|
Sized_relobj<64, true>* object,
|
|
const unsigned char* symbols,
|
|
section_size_type symbols_size,
|
|
const unsigned char* symbol_names,
|
|
section_size_type symbol_names_size,
|
|
unsigned int shndx,
|
|
unsigned int reloc_shndx,
|
|
unsigned int reloc_type);
|
|
#endif
|
|
|
|
} // End namespace gold.
|