// ehframe.cc -- handle exception frame sections for gold
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright (C) 2006-2020 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
#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.
+// runtime. This file also handles discarding duplicate exception
+// frame information.
// The exception frame header starts with four bytes:
// the start of the exception frame header information. The entries
// are in sorted order by starting PC.
-// FIXME: We currently always generate an empty exception frame
-// header.
-
const int eh_frame_hdr_size = 4;
// Construct the exception frame header.
-Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section)
+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_section_(eh_frame_section),
+ eh_frame_data_(eh_frame_data),
+ fde_offsets_(),
+ any_unrecognized_eh_frame_sections_(false)
{
}
-// Set the final address and size of the exception frame header.
+// Set the size of the exception frame header.
void
-Eh_frame_hdr::do_set_address(uint64_t, off_t)
+Eh_frame_hdr::set_final_data_size()
{
- this->set_data_size(eh_frame_hdr_size + 4);
+ 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.
+// Write the data to the file.
void
Eh_frame_hdr::do_write(Output_file* of)
+{
+ switch (parameters->size_and_endianness())
+ {
+#ifdef HAVE_TARGET_32_LITTLE
+ case Parameters::TARGET_32_LITTLE:
+ this->do_sized_write<32, false>(of);
+ break;
+#endif
+#ifdef HAVE_TARGET_32_BIG
+ case Parameters::TARGET_32_BIG:
+ this->do_sized_write<32, true>(of);
+ break;
+#endif
+#ifdef HAVE_TARGET_64_LITTLE
+ case Parameters::TARGET_64_LITTLE:
+ this->do_sized_write<64, false>(of);
+ break;
+#endif
+#ifdef HAVE_TARGET_64_BIG
+ case Parameters::TARGET_64_BIG:
+ this->do_sized_write<64, true>(of);
+ break;
+#endif
+ default:
+ 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();
uint64_t eh_frame_hdr_address = this->address();
uint64_t eh_frame_offset = (eh_frame_address -
(eh_frame_hdr_address + 4));
- if (parameters->is_big_endian())
- elfcpp::Swap<32, true>::writeval(oview + 4, eh_frame_offset);
+ 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
- elfcpp::Swap<32, false>::writeval(oview + 4, eh_frame_offset);
+ {
+ 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();
- // We don't currently write out the sorted table.
- oview[2] = elfcpp::DW_EH_PE_omit;
- oview[3] = elfcpp::DW_EH_PE_omit;
+ 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(oview_size == 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 & 0x70)
+ {
+ case 0:
+ break;
+
+ case elfcpp::DW_EH_PE_pcrel:
+ pc += eh_frame_address + fde_offset + 8;
+ break;
+
+ case elfcpp::DW_EH_PE_datarel:
+ pc += parameters->target().ehframe_datarel_base();
+ 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();
+ }
+
+ gold_assert((fde_encoding & elfcpp::DW_EH_PE_indirect) == 0);
+
+ 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. OUTPUT_OFFSET is the offset of the
+// Eh_frame section within the output section. FDE_ENCODING is the
+// encoding, from the CIE. ADDRALIGN is the required alignment.
+// ADDRESS is the virtual address of OVIEW. 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 output_offset,
+ section_offset_type offset, uint64_t address, 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 this FDE is associated with a PLT, fill in the PLT's address
+ // and size.
+ if (this->object_ == NULL)
+ {
+ gold_assert(memcmp(oview + offset + 8, "\0\0\0\0\0\0\0\0", 8) == 0);
+ uint64_t paddress;
+ off_t psize;
+ parameters->target().plt_fde_location(this->u_.from_linker.plt,
+ oview + offset + 8,
+ &paddress, &psize);
+ uint64_t poffset = paddress - (address + offset + 8);
+ int32_t spoffset = static_cast<int32_t>(poffset);
+ uint32_t upsize = static_cast<uint32_t>(psize);
+ if (static_cast<uint64_t>(static_cast<int64_t>(spoffset)) != poffset
+ || static_cast<off_t>(upsize) != psize)
+ gold_warning(_("overflow in PLT unwind data; "
+ "unwinding through PLT may fail"));
+ elfcpp::Swap<32, big_endian>::writeval(oview + offset + 8, spoffset);
+ elfcpp::Swap<32, big_endian>::writeval(oview + offset + 12, upsize);
+ }
+
+ 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(output_offset + 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,
+ Output_section_data *output_data)
+{
+ size_t length = this->contents_.length();
+
+ // Add 4 for length and 4 for zero CIE identifier tag.
+ length += 8;
+
+ if (this->object_ != NULL)
+ {
+ // Add a mapping so that relocations are applied correctly.
+ this->object_->add_merge_mapping(output_data, 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, output_data);
+
+ 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. OUTPUT_OFFSET is the
+// offset of the Eh_frame section within the output section. Round up
+// the bytes to ADDRALIGN. ADDRESS is the virtual address of OVIEW.
+// EH_FRAME_HDR is the exception frame header for FDE recording.
+// POST_FDES stashes FDEs created after mappings were done, for later
+// writing. Return the new offset.
+
+template<int size, bool big_endian>
+section_offset_type
+Cie::write(unsigned char* oview, section_offset_type output_offset,
+ section_offset_type offset, uint64_t address,
+ unsigned int addralign, Eh_frame_hdr* eh_frame_hdr,
+ Post_fdes* post_fdes)
+{
+ 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)
+ {
+ if ((*p)->post_map())
+ post_fdes->push_back(Post_fde(*p, cie_offset, fde_encoding));
+ else
+ offset = (*p)->write<size, big_endian>(oview, output_offset, offset,
+ address, 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_(),
+ mappings_are_done_(false),
+ final_data_size_(0)
+{
+}
+
+// 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>
+Eh_frame::Eh_frame_section_disposition
+Eh_frame::add_ehframe_input_section(
+ Sized_relobj_file<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 EH_EMPTY_SECTION;
+
+ // 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 EH_END_MARKER_SECTION;
+
+ 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))
+ {
+ if (this->eh_frame_hdr_ != NULL)
+ 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 EH_UNRECOGNIZED_SECTION;
+ }
+
+ // 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 EH_OPTIMIZABLE_SECTION;
+}
+
+// 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_file<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)
+{
+ 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_file<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.
+ object->add_merge_mapping(this, 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_file<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;
+
+ int pc_size = 0;
+ switch (cie->fde_encoding() & 7)
+ {
+ case elfcpp::DW_EH_PE_udata2:
+ pc_size = 2;
+ break;
+ case elfcpp::DW_EH_PE_udata4:
+ pc_size = 4;
+ break;
+ case elfcpp::DW_EH_PE_udata8:
+ gold_assert(size == 64);
+ pc_size = 8;
+ break;
+ case elfcpp::DW_EH_PE_absptr:
+ pc_size = size == 32 ? 4 : 8;
+ break;
+ default:
+ // All other cases were rejected in Eh_frame::read_cie.
+ gold_unreachable();
+ }
+
+ // 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)
+ {
+ // In an object produced by a relocatable link, gold may have
+ // discarded a COMDAT group in the previous link, but not the
+ // corresponding FDEs. In that case, gold will have discarded
+ // the relocations, so the FDE will have a non-relocatable zero
+ // (regardless of whether the PC encoding is absolute, pc-relative,
+ // or data-relative) instead of a pointer to the start of the code.
+
+ uint64_t pc_value = 0;
+ switch (pc_size)
+ {
+ case 2:
+ pc_value = elfcpp::Swap<16, big_endian>::readval(pfde);
+ break;
+ case 4:
+ pc_value = elfcpp::Swap<32, big_endian>::readval(pfde);
+ break;
+ case 8:
+ pc_value = elfcpp::Swap_unaligned<64, big_endian>::readval(pfde);
+ break;
+ default:
+ gold_unreachable();
+ }
+
+ if (pc_value == 0)
+ {
+ // This FDE applies to a discarded function. We
+ // can discard this FDE.
+ object->add_merge_mapping(this, shndx, (pfde - 8) - pcontents,
+ pfdeend - (pfde - 8), -1);
+ return true;
+ }
+
+ // Otherwise, reject the FDE.
+ 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);
+
+ // Find the section index for code that this FDE describes.
+ // If we have discarded the section, we can also discard the FDE.
+ 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);
+ bool is_ordinary;
+ fde_shndx = object->adjust_sym_shndx(symndx, sym.get_st_shndx(),
+ &is_ordinary);
+ bool is_discarded = (is_ordinary
+ && fde_shndx != elfcpp::SHN_UNDEF
+ && fde_shndx < object->shnum()
+ && !object->is_section_included(fde_shndx));
+
+ // Fetch the address range field from the FDE. The offset and size
+ // of the field depends on the PC encoding given in the CIE, but
+ // it is always an absolute value. If the address range is 0, this
+ // FDE corresponds to a function that was discarded during optimization
+ // (too late to discard the corresponding FDE).
+ uint64_t address_range = 0;
+ switch (pc_size)
+ {
+ case 2:
+ address_range = elfcpp::Swap<16, big_endian>::readval(pfde + 2);
+ break;
+ case 4:
+ address_range = elfcpp::Swap<32, big_endian>::readval(pfde + 4);
+ break;
+ case 8:
+ address_range = elfcpp::Swap_unaligned<64, big_endian>::readval(pfde + 8);
+ break;
+ default:
+ gold_unreachable();
+ }
+
+ if (is_discarded || address_range == 0)
+ {
+ // This FDE applies to a discarded function. We
+ // can discard this FDE.
+ object->add_merge_mapping(this, 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;
+}
+
+// Add unwind information for a PLT.
+
+void
+Eh_frame::add_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data,
+ size_t cie_length, const unsigned char* fde_data,
+ size_t fde_length)
+{
+ Cie cie(NULL, 0, 0, elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4, "",
+ cie_data, cie_length);
+ Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
+ Cie* pcie;
+ if (find_cie != this->cie_offsets_.end())
+ pcie = *find_cie;
+ else
+ {
+ gold_assert(!this->mappings_are_done_);
+ pcie = new Cie(cie);
+ this->cie_offsets_.insert(pcie);
+ }
+
+ Fde* fde = new Fde(plt, fde_data, fde_length, this->mappings_are_done_);
+ pcie->add_fde(fde);
+
+ if (this->mappings_are_done_)
+ this->final_data_size_ += align_address(fde_length + 8, this->addralign());
+}
+
+// Remove all post-map unwind information for a PLT.
+
+void
+Eh_frame::remove_ehframe_for_plt(Output_data* plt,
+ const unsigned char* cie_data,
+ size_t cie_length)
+{
+ if (!this->mappings_are_done_)
+ return;
+
+ Cie cie(NULL, 0, 0, elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4, "",
+ cie_data, cie_length);
+ Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
+ gold_assert (find_cie != this->cie_offsets_.end());
+ Cie* pcie = *find_cie;
+
+ while (pcie->fde_count() != 0)
+ {
+ const Fde* fde = pcie->last_fde();
+ if (!fde->post_map(plt))
+ break;
+ size_t length = fde->length();
+ this->final_data_size_ -= align_address(length + 8, this->addralign());
+ pcie->remove_fde();
+ }
+}
+
+// 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()
+{
+ // We can be called more than once if Layout::set_segment_offsets
+ // finds a better mapping. We don't want to add all the mappings
+ // again.
+ if (this->mappings_are_done_)
+ {
+ this->set_data_size(this->final_data_size_);
+ return;
+ }
+
+ section_offset_type output_start = 0;
+ if (this->is_offset_valid())
+ output_start = this->offset() - this->output_section()->offset();
+ section_offset_type output_offset = output_start;
+
+ 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);
+
+ 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);
+
+ this->mappings_are_done_ = true;
+ this->final_data_size_ = output_offset - output_start;
+
+ gold_assert((output_offset & (this->addralign() - 1)) == 0);
+ this->set_data_size(this->final_data_size_);
+}
+
+// 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 object->merge_output_offset(shndx, offset, poutput);
+}
+
+// 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);
+
+ switch (parameters->size_and_endianness())
+ {
+#ifdef HAVE_TARGET_32_LITTLE
+ case Parameters::TARGET_32_LITTLE:
+ this->do_sized_write<32, false>(oview);
+ break;
+#endif
+#ifdef HAVE_TARGET_32_BIG
+ case Parameters::TARGET_32_BIG:
+ this->do_sized_write<32, true>(oview);
+ break;
+#endif
+#ifdef HAVE_TARGET_64_LITTLE
+ case Parameters::TARGET_64_LITTLE:
+ this->do_sized_write<64, false>(oview);
+ break;
+#endif
+#ifdef HAVE_TARGET_64_BIG
+ case Parameters::TARGET_64_BIG:
+ this->do_sized_write<64, true>(oview);
+ break;
+#endif
+ default:
+ 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)
+{
+ uint64_t address = this->address();
+ unsigned int addralign = this->addralign();
+ section_offset_type o = 0;
+ const off_t output_offset = this->offset() - this->output_section()->offset();
+ Post_fdes post_fdes;
+ 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, output_offset, o, address,
+ addralign, this->eh_frame_hdr_,
+ &post_fdes);
+ for (Cie_offsets::iterator p = this->cie_offsets_.begin();
+ p != this->cie_offsets_.end();
+ ++p)
+ o = (*p)->write<size, big_endian>(oview, output_offset, o, address,
+ addralign, this->eh_frame_hdr_,
+ &post_fdes);
+ for (Post_fdes::iterator p = post_fdes.begin();
+ p != post_fdes.end();
+ ++p)
+ o = (*p).fde->write<size, big_endian>(oview, output_offset, o, address,
+ addralign, (*p).cie_offset,
+ (*p).fde_encoding,
+ this->eh_frame_hdr_);
+}
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
+Eh_frame::Eh_frame_section_disposition
+Eh_frame::add_ehframe_input_section<32, false>(
+ Sized_relobj_file<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
+Eh_frame::Eh_frame_section_disposition
+Eh_frame::add_ehframe_input_section<32, true>(
+ Sized_relobj_file<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
+Eh_frame::Eh_frame_section_disposition
+Eh_frame::add_ehframe_input_section<64, false>(
+ Sized_relobj_file<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
+Eh_frame::Eh_frame_section_disposition
+Eh_frame::add_ehframe_input_section<64, true>(
+ Sized_relobj_file<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.
projects / deliverable / binutils-gdb.git / blobdiff