2015-07-25 05:03:07 +08:00
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//===- Writer.cpp ---------------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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2015-09-05 06:48:30 +08:00
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#include "Writer.h"
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2015-08-06 07:51:50 +08:00
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#include "Config.h"
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2015-09-22 05:38:08 +08:00
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#include "OutputSections.h"
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2015-08-06 07:24:46 +08:00
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#include "SymbolTable.h"
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2015-09-23 02:19:46 +08:00
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#include "Target.h"
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2015-08-12 08:00:24 +08:00
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2015-08-06 07:24:46 +08:00
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#include "llvm/Support/FileOutputBuffer.h"
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2015-07-25 05:03:07 +08:00
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using namespace llvm;
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using namespace llvm::ELF;
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using namespace llvm::object;
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using namespace lld;
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using namespace lld::elf2;
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static const int PageSize = 4096;
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2015-09-11 21:20:07 +08:00
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// On freebsd x86_64 the first page cannot be mmaped.
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// On linux that is controled by vm.mmap_min_addr. At least on some x86_64
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// installs that is 65536, so the first 15 pages cannot be used.
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// Given that, the smallest value that can be used in here is 0x10000.
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2015-09-10 23:41:34 +08:00
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// If using 2MB pages, the smallest page aligned address that works is
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// 0x200000, but it looks like every OS uses 4k pages for executables.
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// FIXME: This is architecture and OS dependent.
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static const int VAStart = 0x10000;
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2015-08-06 07:24:46 +08:00
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namespace {
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2015-09-09 03:43:27 +08:00
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2015-10-03 05:23:17 +08:00
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static uint32_t toPHDRFlags(uint64_t Flags) {
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2015-09-18 03:58:07 +08:00
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uint32_t Ret = PF_R;
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if (Flags & SHF_WRITE)
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Ret |= PF_W;
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if (Flags & SHF_EXECINSTR)
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Ret |= PF_X;
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return Ret;
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}
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2015-10-03 06:17:07 +08:00
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template <class ELFT> struct ProgramHeader {
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typedef typename ELFFile<ELFT>::uintX_t uintX_t;
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typedef typename ELFFile<ELFT>::Elf_Phdr Elf_Phdr;
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2015-09-18 03:58:07 +08:00
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2015-10-03 05:23:17 +08:00
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ProgramHeader(uintX_t Type, uintX_t Flags, uintX_t FileOff, uintX_t VA) {
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2015-10-03 06:17:07 +08:00
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std::memset(&Header, 0, sizeof(Elf_Phdr));
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2015-10-03 05:13:19 +08:00
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Header.p_type = Type;
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Header.p_flags = Flags;
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2015-09-18 03:58:07 +08:00
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Header.p_align = PageSize;
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2015-10-03 05:23:17 +08:00
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Header.p_offset = FileOff;
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Header.p_vaddr = VA;
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Header.p_paddr = VA;
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2015-09-18 03:58:07 +08:00
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}
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2015-10-03 06:17:07 +08:00
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void setValuesFromSection(OutputSectionBase<ELFT::Is64Bits> &Sec) {
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2015-10-03 05:23:17 +08:00
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Header.p_flags = toPHDRFlags(Sec.getFlags());
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2015-09-18 03:58:07 +08:00
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Header.p_offset = Sec.getFileOff();
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Header.p_vaddr = Sec.getVA();
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Header.p_paddr = Header.p_vaddr;
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Header.p_filesz = Sec.getSize();
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Header.p_memsz = Header.p_filesz;
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Header.p_align = Sec.getAlign();
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}
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2015-10-03 06:17:07 +08:00
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Elf_Phdr Header;
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2015-09-18 03:58:07 +08:00
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bool Closed = false;
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};
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2015-08-06 07:24:46 +08:00
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// The writer writes a SymbolTable result to a file.
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template <class ELFT> class Writer {
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public:
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2015-09-09 05:57:31 +08:00
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typedef typename ELFFile<ELFT>::uintX_t uintX_t;
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typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
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typedef typename ELFFile<ELFT>::Elf_Ehdr Elf_Ehdr;
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typedef typename ELFFile<ELFT>::Elf_Phdr Elf_Phdr;
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typedef typename ELFFile<ELFT>::Elf_Sym Elf_Sym;
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2015-09-17 04:45:57 +08:00
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typedef typename ELFFile<ELFT>::Elf_Sym_Range Elf_Sym_Range;
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2015-09-16 23:54:15 +08:00
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typedef typename ELFFile<ELFT>::Elf_Rela Elf_Rela;
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2015-09-09 23:33:08 +08:00
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Writer(SymbolTable *T)
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2015-09-24 02:25:05 +08:00
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: SymTabSec(*T, StrTabSec, BssSec), DynSymSec(*T, DynStrSec, BssSec),
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2015-10-06 05:23:08 +08:00
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RelaDynSec(DynSymSec, GotSec, BssSec, T->shouldUseRela()),
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PltSec(GotSec), HashSec(DynSymSec),
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DynamicSec(*T, HashSec, RelaDynSec, BssSec),
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2015-09-24 02:25:05 +08:00
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BssSec(PltSec, GotSec, BssSec, ".bss", SHT_NOBITS,
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SHF_ALLOC | SHF_WRITE) {}
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2015-08-06 07:24:46 +08:00
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void run();
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private:
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void createSections();
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2015-09-17 22:02:10 +08:00
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template <bool isRela>
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2015-09-22 01:47:00 +08:00
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void scanRelocs(const InputSection<ELFT> &C,
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2015-09-17 22:02:10 +08:00
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iterator_range<const Elf_Rel_Impl<ELFT, isRela> *> Rels);
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2015-09-22 01:47:00 +08:00
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void scanRelocs(const InputSection<ELFT> &C);
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2015-08-06 07:24:46 +08:00
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void assignAddresses();
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void openFile(StringRef OutputPath);
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void writeHeader();
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void writeSections();
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2015-09-12 02:49:42 +08:00
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bool needsInterpSection() const {
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return !SymTabSec.getSymTable().getSharedFiles().empty() &&
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!Config->DynamicLinker.empty();
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}
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2015-09-12 06:42:45 +08:00
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bool needsDynamicSections() const {
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return !SymTabSec.getSymTable().getSharedFiles().empty() || Config->Shared;
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}
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unsigned getVAStart() const { return Config->Shared ? 0 : VAStart; }
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2015-08-06 07:24:46 +08:00
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std::unique_ptr<llvm::FileOutputBuffer> Buffer;
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2015-09-18 03:58:07 +08:00
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2015-08-14 06:21:37 +08:00
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llvm::SpecificBumpPtrAllocator<OutputSection<ELFT>> CAlloc;
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2015-08-14 06:14:37 +08:00
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std::vector<OutputSectionBase<ELFT::Is64Bits> *> OutputSections;
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2015-09-09 01:39:39 +08:00
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unsigned getNumSections() const { return OutputSections.size() + 1; }
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2015-08-06 07:24:46 +08:00
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2015-09-18 03:58:07 +08:00
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llvm::BumpPtrAllocator PAlloc;
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2015-10-03 06:17:07 +08:00
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std::vector<ProgramHeader<ELFT> *> PHDRs;
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ProgramHeader<ELFT> FileHeaderPHDR{PT_LOAD, PF_R, 0, 0};
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ProgramHeader<ELFT> InterpPHDR{PT_INTERP, 0, 0, 0};
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ProgramHeader<ELFT> DynamicPHDR{PT_DYNAMIC, 0, 0, 0};
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2015-09-18 03:58:07 +08:00
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2015-08-12 07:14:13 +08:00
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uintX_t FileSize;
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2015-09-10 04:48:09 +08:00
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uintX_t ProgramHeaderOff;
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2015-08-06 07:24:46 +08:00
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uintX_t SectionHeaderOff;
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2015-08-14 06:14:37 +08:00
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2015-09-15 04:32:41 +08:00
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StringTableSection<ELFT::Is64Bits> StrTabSec = { /*dynamic=*/false };
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StringTableSection<ELFT::Is64Bits> DynStrSec = { /*dynamic=*/true };
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2015-08-14 06:14:37 +08:00
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2015-09-22 05:38:08 +08:00
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lld::elf2::SymbolTableSection<ELFT> SymTabSec;
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lld::elf2::SymbolTableSection<ELFT> DynSymSec;
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2015-09-09 03:43:27 +08:00
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2015-09-16 23:54:15 +08:00
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RelocationSection<ELFT> RelaDynSec;
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2015-09-18 22:40:19 +08:00
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GotSection<ELFT> GotSec;
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2015-09-21 23:11:29 +08:00
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PltSection<ELFT> PltSec;
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2015-09-18 22:40:19 +08:00
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2015-09-15 04:20:34 +08:00
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HashTableSection<ELFT> HashSec;
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2015-09-15 06:08:55 +08:00
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DynamicSection<ELFT> DynamicSec;
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2015-09-12 02:49:42 +08:00
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InterpSection<ELFT::Is64Bits> InterpSec;
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2015-09-24 02:25:05 +08:00
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OutputSection<ELFT> BssSec;
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2015-08-06 07:24:46 +08:00
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};
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} // anonymous namespace
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namespace lld {
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namespace elf2 {
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2015-08-04 22:29:01 +08:00
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template <class ELFT>
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2015-08-06 07:51:50 +08:00
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void writeResult(SymbolTable *Symtab) { Writer<ELFT>(Symtab).run(); }
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2015-08-06 07:24:46 +08:00
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2015-08-06 07:51:50 +08:00
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template void writeResult<ELF32LE>(SymbolTable *);
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template void writeResult<ELF32BE>(SymbolTable *);
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template void writeResult<ELF64LE>(SymbolTable *);
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template void writeResult<ELF64BE>(SymbolTable *);
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2015-08-06 07:24:46 +08:00
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} // namespace elf2
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} // namespace lld
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2015-07-25 05:03:07 +08:00
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// The main function of the writer.
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2015-08-06 07:24:46 +08:00
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template <class ELFT> void Writer<ELFT>::run() {
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2015-07-25 05:03:07 +08:00
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createSections();
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assignAddresses();
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2015-08-06 07:51:50 +08:00
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openFile(Config->OutputFile);
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2015-07-25 05:03:07 +08:00
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writeHeader();
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writeSections();
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error(Buffer->commit());
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}
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2015-08-14 01:04:50 +08:00
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namespace {
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template <bool Is64Bits> struct SectionKey {
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typedef typename std::conditional<Is64Bits, uint64_t, uint32_t>::type uintX_t;
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StringRef Name;
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2015-10-03 05:13:19 +08:00
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uint32_t Type;
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uintX_t Flags;
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2015-08-14 01:04:50 +08:00
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};
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}
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namespace llvm {
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template <bool Is64Bits> struct DenseMapInfo<SectionKey<Is64Bits>> {
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static SectionKey<Is64Bits> getEmptyKey() {
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return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getEmptyKey(), 0, 0};
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}
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static SectionKey<Is64Bits> getTombstoneKey() {
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return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getTombstoneKey(), 0,
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0};
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}
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static unsigned getHashValue(const SectionKey<Is64Bits> &Val) {
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2015-10-03 05:13:19 +08:00
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return hash_combine(Val.Name, Val.Type, Val.Flags);
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2015-08-14 01:04:50 +08:00
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}
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static bool isEqual(const SectionKey<Is64Bits> &LHS,
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const SectionKey<Is64Bits> &RHS) {
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return DenseMapInfo<StringRef>::isEqual(LHS.Name, RHS.Name) &&
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2015-10-03 05:13:19 +08:00
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LHS.Type == RHS.Type && LHS.Flags == RHS.Flags;
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2015-08-14 01:04:50 +08:00
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}
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};
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}
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2015-09-16 23:54:15 +08:00
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// The reason we have to do this early scan is as follows
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// * To mmap the output file, we need to know the size
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// * For that, we need to know how many dynamic relocs we will have.
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// It might be possible to avoid this by outputting the file with write:
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// * Write the allocated output sections, computing addresses.
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// * Apply relocations, recording which ones require a dynamic reloc.
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// * Write the dynamic relocations.
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// * Write the rest of the file.
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2015-09-17 22:02:10 +08:00
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template <class ELFT>
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template <bool isRela>
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void Writer<ELFT>::scanRelocs(
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2015-09-22 01:47:00 +08:00
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const InputSection<ELFT> &C,
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2015-09-17 22:02:10 +08:00
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iterator_range<const Elf_Rel_Impl<ELFT, isRela> *> Rels) {
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typedef Elf_Rel_Impl<ELFT, isRela> RelType;
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const ObjectFile<ELFT> &File = *C.getFile();
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2015-09-24 23:11:50 +08:00
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bool IsMips64EL = File.getObj().isMips64EL();
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2015-09-17 22:02:10 +08:00
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for (const RelType &RI : Rels) {
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uint32_t SymIndex = RI.getSymbol(IsMips64EL);
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2015-09-18 22:40:19 +08:00
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SymbolBody *Body = File.getSymbolBody(SymIndex);
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2015-09-21 23:11:29 +08:00
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uint32_t Type = RI.getType(IsMips64EL);
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2015-10-06 03:30:12 +08:00
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if (Body) {
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if (Target->relocNeedsPlt(Type, *Body)) {
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if (Body->isInPlt())
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continue;
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PltSec.addEntry(Body);
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}
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if (Target->relocNeedsGot(Type, *Body)) {
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if (Body->isInGot())
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continue;
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GotSec.addEntry(Body);
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Body->setUsedInDynamicReloc();
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RelaDynSec.addReloc({C, RI});
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2015-09-21 23:11:29 +08:00
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continue;
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2015-10-06 03:30:12 +08:00
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}
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if (Body->isShared()) {
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Body->setUsedInDynamicReloc();
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RelaDynSec.addReloc({C, RI});
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2015-09-18 22:40:19 +08:00
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continue;
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2015-10-06 03:30:12 +08:00
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}
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}
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if (Config->Shared && !Target->isRelRelative(Type))
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RelaDynSec.addReloc({C, RI});
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2015-09-17 22:02:10 +08:00
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}
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}
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2015-09-16 23:54:15 +08:00
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template <class ELFT>
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2015-09-22 01:47:00 +08:00
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void Writer<ELFT>::scanRelocs(const InputSection<ELFT> &C) {
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2015-09-24 23:11:50 +08:00
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ObjectFile<ELFT> *File = C.getFile();
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ELFFile<ELFT> &EObj = File->getObj();
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2015-09-16 23:54:15 +08:00
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if (!(C.getSectionHdr()->sh_flags & SHF_ALLOC))
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return;
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for (const Elf_Shdr *RelSec : C.RelocSections) {
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2015-09-17 22:02:10 +08:00
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if (RelSec->sh_type == SHT_RELA)
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2015-09-24 23:11:50 +08:00
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scanRelocs(C, EObj.relas(RelSec));
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2015-09-17 22:02:10 +08:00
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else
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2015-09-24 23:11:50 +08:00
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scanRelocs(C, EObj.rels(RelSec));
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2015-09-16 23:54:15 +08:00
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}
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}
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2015-09-23 22:37:01 +08:00
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template <class ELFT>
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2015-10-01 22:46:54 +08:00
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static void reportUndefined(const SymbolTable &S, const SymbolBody &Sym) {
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2015-09-23 22:37:01 +08:00
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typedef typename ELFFile<ELFT>::Elf_Sym Elf_Sym;
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typedef typename ELFFile<ELFT>::Elf_Sym_Range Elf_Sym_Range;
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2015-10-02 04:14:45 +08:00
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if (Config->Shared && !Config->NoUndefined)
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2015-10-02 01:24:24 +08:00
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return;
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2015-09-23 22:37:01 +08:00
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const Elf_Sym &SymE = cast<ELFSymbolBody<ELFT>>(Sym).Sym;
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ELFFileBase *SymFile = nullptr;
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|
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for (const std::unique_ptr<ObjectFileBase> &F : S.getObjectFiles()) {
|
|
|
|
const auto &File = cast<ObjectFile<ELFT>>(*F);
|
2015-09-24 23:11:50 +08:00
|
|
|
Elf_Sym_Range Syms = File.getObj().symbols(File.getSymbolTable());
|
2015-09-23 22:37:01 +08:00
|
|
|
if (&SymE > Syms.begin() && &SymE < Syms.end())
|
|
|
|
SymFile = F.get();
|
|
|
|
}
|
2015-09-26 03:24:57 +08:00
|
|
|
|
|
|
|
std::string Message = "undefined symbol: " + Sym.getName().str();
|
2015-09-23 22:37:01 +08:00
|
|
|
if (SymFile)
|
2015-09-26 03:24:57 +08:00
|
|
|
Message += " in " + SymFile->getName().str();
|
|
|
|
if (Config->NoInhibitExec)
|
|
|
|
warning(Message);
|
2015-09-23 22:37:01 +08:00
|
|
|
else
|
2015-09-26 03:24:57 +08:00
|
|
|
error(Message);
|
2015-09-23 22:37:01 +08:00
|
|
|
}
|
|
|
|
|
2015-07-25 05:03:07 +08:00
|
|
|
// Create output section objects and add them to OutputSections.
|
|
|
|
template <class ELFT> void Writer<ELFT>::createSections() {
|
2015-08-14 06:21:37 +08:00
|
|
|
SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT> *> Map;
|
2015-09-24 02:25:05 +08:00
|
|
|
|
|
|
|
OutputSections.push_back(&BssSec);
|
|
|
|
Map[{BssSec.getName(), BssSec.getType(), BssSec.getFlags()}] = &BssSec;
|
|
|
|
|
2015-09-26 02:56:53 +08:00
|
|
|
SymbolTable &Symtab = SymTabSec.getSymTable();
|
2015-09-16 23:54:15 +08:00
|
|
|
for (const std::unique_ptr<ObjectFileBase> &FileB : Symtab.getObjectFiles()) {
|
|
|
|
auto &File = cast<ObjectFile<ELFT>>(*FileB);
|
2015-09-17 04:45:57 +08:00
|
|
|
if (!Config->DiscardAll) {
|
|
|
|
Elf_Sym_Range Syms = File.getLocalSymbols();
|
|
|
|
for (const Elf_Sym &Sym : Syms) {
|
|
|
|
ErrorOr<StringRef> SymName = Sym.getName(File.getStringTable());
|
2015-10-06 00:25:43 +08:00
|
|
|
if (SymName && shouldKeepInSymtab<ELFT>(*SymName, Sym))
|
2015-09-17 04:45:57 +08:00
|
|
|
SymTabSec.addSymbol(*SymName, true);
|
|
|
|
}
|
|
|
|
}
|
2015-09-22 08:16:19 +08:00
|
|
|
for (InputSection<ELFT> *C : File.getSections()) {
|
2015-09-16 23:54:15 +08:00
|
|
|
if (!C)
|
|
|
|
continue;
|
|
|
|
const Elf_Shdr *H = C->getSectionHdr();
|
2015-09-25 23:08:44 +08:00
|
|
|
SectionKey<ELFT::Is64Bits> Key{C->getSectionName(), H->sh_type,
|
|
|
|
H->sh_flags};
|
|
|
|
OutputSection<ELFT> *&Sec = Map[Key];
|
|
|
|
if (!Sec) {
|
|
|
|
Sec = new (CAlloc.Allocate()) OutputSection<ELFT>(
|
2015-10-03 05:13:19 +08:00
|
|
|
PltSec, GotSec, BssSec, Key.Name, Key.Type, Key.Flags);
|
2015-09-25 23:08:44 +08:00
|
|
|
OutputSections.push_back(Sec);
|
|
|
|
}
|
2015-09-22 08:16:19 +08:00
|
|
|
Sec->addSection(C);
|
2015-09-16 23:54:15 +08:00
|
|
|
scanRelocs(*C);
|
|
|
|
}
|
2015-09-01 08:16:38 +08:00
|
|
|
}
|
|
|
|
|
2015-10-03 03:37:55 +08:00
|
|
|
DynamicSec.PreInitArraySec =
|
|
|
|
Map.lookup({".preinit_array", SHT_PREINIT_ARRAY, SHF_WRITE | SHF_ALLOC});
|
|
|
|
DynamicSec.InitArraySec =
|
|
|
|
Map.lookup({".init_array", SHT_INIT_ARRAY, SHF_WRITE | SHF_ALLOC});
|
|
|
|
DynamicSec.FiniArraySec =
|
|
|
|
Map.lookup({".fini_array", SHT_FINI_ARRAY, SHF_WRITE | SHF_ALLOC});
|
|
|
|
|
|
|
|
if (OutputSection<ELFT> *OS = DynamicSec.InitArraySec) {
|
2015-09-26 02:56:53 +08:00
|
|
|
Symtab.addSyntheticSym<ELFT>("__init_array_start", *OS, 0);
|
|
|
|
Symtab.addSyntheticSym<ELFT>("__init_array_end", *OS, OS->getSize());
|
2015-10-02 05:22:26 +08:00
|
|
|
} else {
|
|
|
|
Symtab.addIgnoredSym<ELFT>("__init_array_start");
|
|
|
|
Symtab.addIgnoredSym<ELFT>("__init_array_end");
|
2015-09-26 02:56:53 +08:00
|
|
|
}
|
|
|
|
|
2015-09-23 07:38:23 +08:00
|
|
|
// FIXME: Try to avoid the extra walk over all global symbols.
|
|
|
|
std::vector<DefinedCommon<ELFT> *> CommonSymbols;
|
|
|
|
for (auto &P : Symtab.getSymbols()) {
|
|
|
|
StringRef Name = P.first;
|
|
|
|
SymbolBody *Body = P.second->Body;
|
2015-10-05 17:43:57 +08:00
|
|
|
if (auto *U = dyn_cast<Undefined<ELFT>>(Body)) {
|
|
|
|
if (!U->isWeak() && !U->canKeepUndefined())
|
|
|
|
reportUndefined<ELFT>(Symtab, *Body);
|
|
|
|
}
|
2015-09-23 07:38:23 +08:00
|
|
|
|
|
|
|
if (auto *C = dyn_cast<DefinedCommon<ELFT>>(Body))
|
|
|
|
CommonSymbols.push_back(C);
|
2015-10-05 23:24:04 +08:00
|
|
|
if (!includeInSymtab<ELFT>(*Body))
|
2015-09-23 07:38:23 +08:00
|
|
|
continue;
|
|
|
|
SymTabSec.addSymbol(Name);
|
|
|
|
|
|
|
|
if (needsDynamicSections() && includeInDynamicSymtab(*Body))
|
|
|
|
HashSec.addSymbol(Body);
|
|
|
|
}
|
|
|
|
|
2015-09-01 08:16:38 +08:00
|
|
|
// Sort the common symbols by alignment as an heuristic to pack them better.
|
2015-09-25 11:48:25 +08:00
|
|
|
std::stable_sort(
|
|
|
|
CommonSymbols.begin(), CommonSymbols.end(),
|
|
|
|
[](const DefinedCommon<ELFT> *A, const DefinedCommon<ELFT> *B) {
|
|
|
|
return A->MaxAlignment > B->MaxAlignment;
|
|
|
|
});
|
|
|
|
|
2015-09-24 02:25:05 +08:00
|
|
|
uintX_t Off = BssSec.getSize();
|
2015-09-01 08:16:38 +08:00
|
|
|
for (DefinedCommon<ELFT> *C : CommonSymbols) {
|
2015-09-01 06:07:18 +08:00
|
|
|
const Elf_Sym &Sym = C->Sym;
|
2015-09-01 09:19:12 +08:00
|
|
|
uintX_t Align = C->MaxAlignment;
|
2015-09-01 06:07:18 +08:00
|
|
|
Off = RoundUpToAlignment(Off, Align);
|
2015-09-01 06:55:21 +08:00
|
|
|
C->OffsetInBSS = Off;
|
2015-09-01 06:07:18 +08:00
|
|
|
Off += Sym.st_size;
|
|
|
|
}
|
2015-09-01 08:16:38 +08:00
|
|
|
|
2015-09-24 02:25:05 +08:00
|
|
|
BssSec.setSize(Off);
|
2015-07-25 05:03:07 +08:00
|
|
|
|
2015-09-11 08:30:13 +08:00
|
|
|
OutputSections.push_back(&SymTabSec);
|
2015-09-09 02:08:57 +08:00
|
|
|
|
2015-09-12 06:42:45 +08:00
|
|
|
if (needsDynamicSections()) {
|
2015-09-12 02:49:42 +08:00
|
|
|
if (needsInterpSection())
|
|
|
|
OutputSections.push_back(&InterpSec);
|
2015-09-11 08:30:13 +08:00
|
|
|
OutputSections.push_back(&DynSymSec);
|
2015-09-15 04:20:34 +08:00
|
|
|
OutputSections.push_back(&HashSec);
|
2015-09-09 03:43:27 +08:00
|
|
|
OutputSections.push_back(&DynamicSec);
|
2015-09-09 23:33:08 +08:00
|
|
|
OutputSections.push_back(&DynStrSec);
|
2015-09-17 17:54:29 +08:00
|
|
|
if (RelaDynSec.hasRelocs())
|
2015-09-16 23:54:15 +08:00
|
|
|
OutputSections.push_back(&RelaDynSec);
|
2015-09-09 23:33:08 +08:00
|
|
|
}
|
2015-09-24 04:08:25 +08:00
|
|
|
if (!GotSec.empty())
|
|
|
|
OutputSections.push_back(&GotSec);
|
|
|
|
if (!PltSec.empty())
|
|
|
|
OutputSections.push_back(&PltSec);
|
2015-09-09 03:43:27 +08:00
|
|
|
|
2015-09-25 11:48:25 +08:00
|
|
|
std::stable_sort(
|
|
|
|
OutputSections.begin(), OutputSections.end(),
|
|
|
|
[](OutputSectionBase<ELFT::Is64Bits> *A,
|
|
|
|
OutputSectionBase<ELFT::Is64Bits> *B) {
|
2015-10-02 05:15:02 +08:00
|
|
|
uintX_t AFlags = A->getFlags();
|
|
|
|
uintX_t BFlags = B->getFlags();
|
|
|
|
|
|
|
|
// Allocatable sections go first to reduce the total PT_LOAD size and
|
|
|
|
// so debug info doesn't change addresses in actual code.
|
|
|
|
bool AIsAlloc = AFlags & SHF_ALLOC;
|
|
|
|
bool BIsAlloc = BFlags & SHF_ALLOC;
|
|
|
|
if (AIsAlloc != BIsAlloc)
|
|
|
|
return AIsAlloc;
|
|
|
|
|
|
|
|
// We don't have any special requirements for the relative order of
|
|
|
|
// two non allocatable sections.
|
|
|
|
if (!AIsAlloc)
|
|
|
|
return false;
|
|
|
|
|
|
|
|
// We want the read only sections first so that they go in the PT_LOAD
|
|
|
|
// covering the program headers at the start of the file.
|
|
|
|
bool AIsWritable = AFlags & SHF_WRITE;
|
|
|
|
bool BIsWritable = BFlags & SHF_WRITE;
|
|
|
|
if (AIsWritable != BIsWritable)
|
|
|
|
return BIsWritable;
|
|
|
|
|
|
|
|
// For a corresponding reason, put non exec sections first (the program
|
|
|
|
// header PT_LOAD is not executable).
|
|
|
|
bool AIsExec = AFlags & SHF_EXECINSTR;
|
|
|
|
bool BIsExec = BFlags & SHF_EXECINSTR;
|
|
|
|
if (AIsExec != BIsExec)
|
|
|
|
return BIsExec;
|
|
|
|
|
|
|
|
// If we got here we know that both A and B and in the same PT_LOAD.
|
|
|
|
// The last requirement we have is to put nobits section last. The
|
|
|
|
// reason is that the only thing the dynamic linker will see about
|
|
|
|
// them is a p_memsz that is larger than p_filesz. Seeing that it
|
|
|
|
// zeros the end of the PT_LOAD, so that has to correspond to the
|
|
|
|
// nobits sections.
|
|
|
|
return A->getType() != SHT_NOBITS && B->getType() == SHT_NOBITS;
|
2015-09-25 11:48:25 +08:00
|
|
|
});
|
|
|
|
|
2015-10-02 05:15:02 +08:00
|
|
|
// Always put StrTabSec last so that no section names are added to it after
|
|
|
|
// it's finalized.
|
|
|
|
OutputSections.push_back(&StrTabSec);
|
|
|
|
|
2015-09-09 02:08:57 +08:00
|
|
|
for (unsigned I = 0, N = OutputSections.size(); I < N; ++I)
|
|
|
|
OutputSections[I]->setSectionIndex(I + 1);
|
2015-10-02 05:15:02 +08:00
|
|
|
|
|
|
|
// Fill the DynStrSec early.
|
|
|
|
DynamicSec.finalize();
|
2015-08-13 23:23:46 +08:00
|
|
|
}
|
|
|
|
|
2015-09-10 04:48:09 +08:00
|
|
|
template <class ELFT>
|
2015-10-03 05:23:17 +08:00
|
|
|
static bool needsPHDR(OutputSectionBase<ELFT::Is64Bits> *Sec) {
|
2015-09-18 03:58:07 +08:00
|
|
|
return Sec->getFlags() & SHF_ALLOC;
|
2015-09-10 04:48:09 +08:00
|
|
|
}
|
|
|
|
|
2015-07-25 05:03:07 +08:00
|
|
|
// Visits all sections to assign incremental, non-overlapping RVAs and
|
|
|
|
// file offsets.
|
|
|
|
template <class ELFT> void Writer<ELFT>::assignAddresses() {
|
2015-09-18 03:58:07 +08:00
|
|
|
assert(!OutputSections.empty() && "No output sections to layout!");
|
2015-09-12 06:42:45 +08:00
|
|
|
uintX_t VA = getVAStart();
|
2015-09-10 23:41:34 +08:00
|
|
|
uintX_t FileOff = 0;
|
2015-09-10 06:53:55 +08:00
|
|
|
|
2015-09-10 23:41:34 +08:00
|
|
|
FileOff += sizeof(Elf_Ehdr);
|
|
|
|
VA += sizeof(Elf_Ehdr);
|
2015-09-10 04:48:09 +08:00
|
|
|
|
|
|
|
// Reserve space for PHDRs.
|
|
|
|
ProgramHeaderOff = FileOff;
|
|
|
|
FileOff = RoundUpToAlignment(FileOff, PageSize);
|
2015-09-10 23:41:34 +08:00
|
|
|
VA = RoundUpToAlignment(VA, PageSize);
|
2015-08-13 23:23:46 +08:00
|
|
|
|
2015-09-12 02:49:42 +08:00
|
|
|
if (needsInterpSection())
|
2015-09-18 03:58:07 +08:00
|
|
|
PHDRs.push_back(&InterpPHDR);
|
2015-09-12 02:49:42 +08:00
|
|
|
|
2015-09-18 03:58:07 +08:00
|
|
|
// Create a PHDR for the file header.
|
|
|
|
PHDRs.push_back(&FileHeaderPHDR);
|
|
|
|
FileHeaderPHDR.Header.p_vaddr = getVAStart();
|
|
|
|
FileHeaderPHDR.Header.p_paddr = getVAStart();
|
|
|
|
FileHeaderPHDR.Header.p_align = PageSize;
|
2015-09-10 23:41:34 +08:00
|
|
|
|
2015-08-14 06:14:37 +08:00
|
|
|
for (OutputSectionBase<ELFT::Is64Bits> *Sec : OutputSections) {
|
2015-09-09 23:33:08 +08:00
|
|
|
StrTabSec.add(Sec->getName());
|
2015-08-14 06:14:37 +08:00
|
|
|
Sec->finalize();
|
|
|
|
|
2015-09-18 03:58:07 +08:00
|
|
|
if (Sec->getSize()) {
|
2015-10-03 05:23:17 +08:00
|
|
|
uintX_t Flags = toPHDRFlags(Sec->getFlags());
|
2015-10-03 06:17:07 +08:00
|
|
|
ProgramHeader<ELFT> *Last = PHDRs.back();
|
2015-10-03 05:23:17 +08:00
|
|
|
if (Last->Header.p_flags != Flags || !needsPHDR<ELFT>(Sec)) {
|
2015-09-18 03:58:07 +08:00
|
|
|
// Flags changed. End current PHDR and potentially create a new one.
|
2015-10-03 05:23:17 +08:00
|
|
|
if (!Last->Closed) {
|
|
|
|
Last->Header.p_filesz = FileOff - Last->Header.p_offset;
|
|
|
|
Last->Header.p_memsz = VA - Last->Header.p_vaddr;
|
|
|
|
Last->Closed = true;
|
2015-09-18 03:58:07 +08:00
|
|
|
}
|
|
|
|
|
2015-10-03 05:23:17 +08:00
|
|
|
if (needsPHDR<ELFT>(Sec)) {
|
2015-09-18 03:58:07 +08:00
|
|
|
VA = RoundUpToAlignment(VA, PageSize);
|
|
|
|
FileOff = RoundUpToAlignment(FileOff, PageSize);
|
2015-10-03 06:17:07 +08:00
|
|
|
PHDRs.push_back(new (PAlloc)
|
|
|
|
ProgramHeader<ELFT>(PT_LOAD, Flags, FileOff, VA));
|
2015-09-18 03:58:07 +08:00
|
|
|
}
|
|
|
|
}
|
2015-09-10 04:48:09 +08:00
|
|
|
}
|
|
|
|
|
2015-08-14 04:24:18 +08:00
|
|
|
uintX_t Align = Sec->getAlign();
|
|
|
|
uintX_t Size = Sec->getSize();
|
2015-08-13 23:31:17 +08:00
|
|
|
if (Sec->getFlags() & SHF_ALLOC) {
|
2015-09-15 03:00:35 +08:00
|
|
|
VA = RoundUpToAlignment(VA, Align);
|
2015-08-13 23:31:17 +08:00
|
|
|
Sec->setVA(VA);
|
2015-09-15 03:00:35 +08:00
|
|
|
VA += Size;
|
2015-08-13 23:31:17 +08:00
|
|
|
}
|
2015-09-15 03:00:35 +08:00
|
|
|
FileOff = RoundUpToAlignment(FileOff, Align);
|
2015-07-25 05:03:07 +08:00
|
|
|
Sec->setFileOffset(FileOff);
|
2015-09-01 04:23:57 +08:00
|
|
|
if (Sec->getType() != SHT_NOBITS)
|
2015-09-15 03:00:35 +08:00
|
|
|
FileOff += Size;
|
2015-07-25 05:03:07 +08:00
|
|
|
}
|
2015-08-12 08:00:24 +08:00
|
|
|
|
2015-09-10 04:48:09 +08:00
|
|
|
// Add a PHDR for the dynamic table.
|
2015-09-12 06:42:45 +08:00
|
|
|
if (needsDynamicSections())
|
2015-09-18 03:58:07 +08:00
|
|
|
PHDRs.push_back(&DynamicPHDR);
|
2015-09-10 04:48:09 +08:00
|
|
|
|
2015-08-12 09:45:28 +08:00
|
|
|
FileOff += OffsetToAlignment(FileOff, ELFT::Is64Bits ? 8 : 4);
|
|
|
|
|
2015-07-29 08:30:10 +08:00
|
|
|
// Add space for section headers.
|
|
|
|
SectionHeaderOff = FileOff;
|
2015-09-09 05:57:31 +08:00
|
|
|
FileOff += getNumSections() * sizeof(Elf_Shdr);
|
2015-09-10 04:48:09 +08:00
|
|
|
FileSize = FileOff;
|
2015-07-25 05:03:07 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
template <class ELFT> void Writer<ELFT>::writeHeader() {
|
|
|
|
uint8_t *Buf = Buffer->getBufferStart();
|
2015-09-09 05:57:31 +08:00
|
|
|
auto *EHdr = reinterpret_cast<Elf_Ehdr *>(Buf);
|
2015-07-25 05:03:07 +08:00
|
|
|
EHdr->e_ident[EI_MAG0] = 0x7F;
|
|
|
|
EHdr->e_ident[EI_MAG1] = 0x45;
|
|
|
|
EHdr->e_ident[EI_MAG2] = 0x4C;
|
|
|
|
EHdr->e_ident[EI_MAG3] = 0x46;
|
2015-08-05 23:08:40 +08:00
|
|
|
EHdr->e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
|
|
|
|
EHdr->e_ident[EI_DATA] = ELFT::TargetEndianness == llvm::support::little
|
|
|
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? ELFDATA2LSB
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|
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: ELFDATA2MSB;
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2015-07-25 05:03:07 +08:00
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EHdr->e_ident[EI_VERSION] = EV_CURRENT;
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2015-09-25 09:59:13 +08:00
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|
|
|
|
|
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const SymbolTable &Symtab = SymTabSec.getSymTable();
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|
|
|
auto &FirstObj = cast<ObjectFile<ELFT>>(*Symtab.getFirstELF());
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|
|
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EHdr->e_ident[EI_OSABI] = FirstObj.getOSABI();
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2015-07-25 05:03:07 +08:00
|
|
|
|
2015-09-09 06:55:28 +08:00
|
|
|
// FIXME: Generalize the segment construction similar to how we create
|
|
|
|
// output sections.
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|
|
|
|
2015-09-12 06:42:45 +08:00
|
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|
EHdr->e_type = Config->Shared ? ET_DYN : ET_EXEC;
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2015-09-04 04:03:54 +08:00
|
|
|
EHdr->e_machine = FirstObj.getEMachine();
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2015-07-25 05:03:07 +08:00
|
|
|
EHdr->e_version = EV_CURRENT;
|
2015-09-12 06:42:45 +08:00
|
|
|
SymbolBody *Entry = Symtab.getEntrySym();
|
2015-09-26 02:19:03 +08:00
|
|
|
EHdr->e_entry =
|
|
|
|
Entry ? getSymVA(cast<ELFSymbolBody<ELFT>>(*Entry), BssSec) : 0;
|
2015-09-10 04:48:09 +08:00
|
|
|
EHdr->e_phoff = ProgramHeaderOff;
|
2015-07-29 08:30:10 +08:00
|
|
|
EHdr->e_shoff = SectionHeaderOff;
|
2015-09-09 05:57:31 +08:00
|
|
|
EHdr->e_ehsize = sizeof(Elf_Ehdr);
|
|
|
|
EHdr->e_phentsize = sizeof(Elf_Phdr);
|
2015-09-18 03:58:07 +08:00
|
|
|
EHdr->e_phnum = PHDRs.size();
|
2015-09-09 05:57:31 +08:00
|
|
|
EHdr->e_shentsize = sizeof(Elf_Shdr);
|
2015-09-09 01:39:39 +08:00
|
|
|
EHdr->e_shnum = getNumSections();
|
2015-09-09 23:33:08 +08:00
|
|
|
EHdr->e_shstrndx = StrTabSec.getSectionIndex();
|
2015-07-25 05:03:07 +08:00
|
|
|
|
2015-09-18 03:58:07 +08:00
|
|
|
// If nothing was merged into the file header PT_LOAD, set the size correctly.
|
2015-10-03 06:17:07 +08:00
|
|
|
if (FileHeaderPHDR.Header.p_filesz == PageSize) {
|
|
|
|
uint64_t Size = sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * PHDRs.size();
|
|
|
|
FileHeaderPHDR.Header.p_filesz = Size;
|
|
|
|
FileHeaderPHDR.Header.p_memsz = Size;
|
|
|
|
}
|
2015-09-12 02:49:42 +08:00
|
|
|
|
2015-09-18 03:58:07 +08:00
|
|
|
if (needsInterpSection())
|
|
|
|
InterpPHDR.setValuesFromSection(InterpSec);
|
|
|
|
if (needsDynamicSections())
|
|
|
|
DynamicPHDR.setValuesFromSection(DynamicSec);
|
2015-07-29 08:30:10 +08:00
|
|
|
|
2015-09-18 03:58:07 +08:00
|
|
|
auto PHdrs = reinterpret_cast<Elf_Phdr *>(Buf + EHdr->e_phoff);
|
2015-10-03 06:17:07 +08:00
|
|
|
for (ProgramHeader<ELFT> *PHDR : PHDRs)
|
|
|
|
*PHdrs++ = PHDR->Header;
|
2015-09-09 06:55:28 +08:00
|
|
|
|
2015-09-09 05:57:31 +08:00
|
|
|
auto SHdrs = reinterpret_cast<Elf_Shdr *>(Buf + EHdr->e_shoff);
|
2015-07-29 08:30:10 +08:00
|
|
|
// First entry is null.
|
|
|
|
++SHdrs;
|
2015-08-14 06:14:37 +08:00
|
|
|
for (OutputSectionBase<ELFT::Is64Bits> *Sec : OutputSections) {
|
2015-09-09 23:33:08 +08:00
|
|
|
Sec->setNameOffset(StrTabSec.getFileOff(Sec->getName()));
|
2015-08-14 02:37:23 +08:00
|
|
|
Sec->template writeHeaderTo<ELFT::TargetEndianness>(SHdrs++);
|
2015-08-12 08:00:24 +08:00
|
|
|
}
|
2015-07-25 05:03:07 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
template <class ELFT> void Writer<ELFT>::openFile(StringRef Path) {
|
2015-08-13 08:31:46 +08:00
|
|
|
ErrorOr<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
|
|
|
|
FileOutputBuffer::create(Path, FileSize, FileOutputBuffer::F_executable);
|
|
|
|
error(BufferOrErr, Twine("failed to open ") + Path);
|
|
|
|
Buffer = std::move(*BufferOrErr);
|
2015-07-25 05:03:07 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
// Write section contents to a mmap'ed file.
|
|
|
|
template <class ELFT> void Writer<ELFT>::writeSections() {
|
|
|
|
uint8_t *Buf = Buffer->getBufferStart();
|
2015-08-14 06:14:37 +08:00
|
|
|
for (OutputSectionBase<ELFT::Is64Bits> *Sec : OutputSections)
|
2015-08-14 13:17:30 +08:00
|
|
|
Sec->writeTo(Buf + Sec->getFileOff());
|
2015-07-25 05:03:07 +08:00
|
|
|
}
|