// ehframe.cc -- handle exception frame sections for gold
-// Copyright (C) 2006-2015 Free Software Foundation, Inc.
+// Copyright (C) 2006-2019 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// Class Fde.
+bool
+Fde::operator==(const Fde& that) const
+{
+ if (this->object_ != that.object_
+ || this->contents_ != that.contents_)
+ return false;
+ if (this->object_ == NULL)
+ return (this->u_.from_linker.plt == that.u_.from_linker.plt
+ && this->u_.from_linker.post_map == that.u_.from_linker.post_map);
+ else
+ return (this->u_.from_object.shndx == that.u_.from_object.shndx
+ && (this->u_.from_object.input_offset
+ == that.u_.from_object.input_offset));
+}
+
// 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
return output_offset + length;
}
+// Remove FDE. Only the last FDE using this CIE may be removed.
+
+void
+Cie::remove_fde(const Fde* fde)
+{
+ gold_assert(*fde == *this->fdes_.back());
+ this->fdes_.pop_back();
+}
+
// 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.
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)
- return false;
+ {
+ // 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)
// 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)
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_ordinary
- && fde_shndx != elfcpp::SHN_UNDEF
- && fde_shndx < object->shnum()
- && !object->is_section_included(fde_shndx))
+ if (is_discarded || address_range == 0)
{
- // This FDE applies to a section which we are discarding. We
+ // 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);
this->final_data_size_ += align_address(fde_length + 8, this->addralign());
}
+// Remove unwind information for a PLT. Only the last FDE added may be removed.
+
+void
+Eh_frame::remove_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);
+ gold_assert (find_cie != this->cie_offsets_.end());
+ Cie* pcie = *find_cie;
+
+ Fde* fde = new Fde(plt, fde_data, fde_length, this->mappings_are_done_);
+ pcie->remove_fde(fde);
+
+ if (this->mappings_are_done_)
+ this->final_data_size_ -= align_address(fde_length + 8, this->addralign());
+}
+
// Return the number of FDEs.
unsigned int
projects / external / binutils.git / blobdiff