Commit c6ebc651 authored by Simon Atanasyan's avatar Simon Atanasyan
Browse files

[LLD] Support compressed input sections on big-endian targets 

This patch enables compressed input sections on big-endian targets by
checking the target endianness and selecting an appropriate `Chdr`
structure.

Fixes PR51369

Differential Revision: https://reviews.llvm.org/D107635
parent 4c2e0123

lld/ELF/InputSection.cpp

+20 −27
Original line number Diff line number Diff line
@@ -88,7 +88,22 @@ InputSectionBase::InputSectionBase(InputFile *file, uint64_t flags, 
    if (!zlib::isAvailable())

      error(toString(file) + ": contains a compressed section, " +

            "but zlib is not available");

    parseCompressedHeader();

    switch (config->ekind) {

    case ELF32LEKind:

      parseCompressedHeader<ELF32LE>();

      break;

    case ELF32BEKind:

      parseCompressedHeader<ELF32BE>();

      break;

    case ELF64LEKind:

      parseCompressedHeader<ELF64LE>();

      break;

    case ELF64BEKind:

      parseCompressedHeader<ELF64BE>();

      break;

    default:

      llvm_unreachable("unknown ELFT");

    }

  }

}
@@ -210,10 +225,7 @@ OutputSection *SectionBase::getOutputSection() { 
// When a section is compressed, `rawData` consists with a header followed

// by zlib-compressed data. This function parses a header to initialize

// `uncompressedSize` member and remove the header from `rawData`.

void InputSectionBase::parseCompressedHeader() {

  using Chdr64 = typename ELF64LE::Chdr;

  using Chdr32 = typename ELF32LE::Chdr;



template <typename ELFT> void InputSectionBase::parseCompressedHeader() {

  // Old-style header

  if (name.startswith(".zdebug")) {

    if (!toStringRef(rawData).startswith("ZLIB")) {
@@ -239,32 +251,13 @@ void InputSectionBase::parseCompressedHeader() { 
  assert(flags & SHF_COMPRESSED);

  flags &= ~(uint64_t)SHF_COMPRESSED;



  // New-style 64-bit header

  if (config->is64) {

    if (rawData.size() < sizeof(Chdr64)) {

      error(toString(this) + ": corrupted compressed section");

      return;

    }



    auto *hdr = reinterpret_cast<const Chdr64 *>(rawData.data());

    if (hdr->ch_type != ELFCOMPRESS_ZLIB) {

      error(toString(this) + ": unsupported compression type");

      return;

    }



    uncompressedSize = hdr->ch_size;

    alignment = std::max<uint32_t>(hdr->ch_addralign, 1);

    rawData = rawData.slice(sizeof(*hdr));

    return;

  }



  // New-style 32-bit header

  if (rawData.size() < sizeof(Chdr32)) {

  // New-style header

  if (rawData.size() < sizeof(typename ELFT::Chdr)) {

    error(toString(this) + ": corrupted compressed section");

    return;

  }



  auto *hdr = reinterpret_cast<const Chdr32 *>(rawData.data());

  auto *hdr = reinterpret_cast<const typename ELFT::Chdr *>(rawData.data());

  if (hdr->ch_type != ELFCOMPRESS_ZLIB) {

    error(toString(this) + ": unsupported compression type");

    return;

lld/ELF/InputSection.h

+1 −0
Original line number Diff line number Diff line
@@ -238,6 +238,7 @@ public: 
  }



protected:

  template <typename ELFT>

  void parseCompressedHeader();

  void uncompress() const;

lld/test/ELF/compressed-debug-input-err.s

+3 −0
Original line number Diff line number Diff line
@@ -3,6 +3,9 @@ 
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o

# RUN: not ld.lld %t.o -o /dev/null -shared 2>&1 | FileCheck %s



# RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-unknown %s -o %t-be.o

# RUN: not ld.lld %t-be.o -o /dev/null -shared 2>&1 | FileCheck %s



## Check we are able to report zlib uncompress errors.

# CHECK: error: {{.*}}.o:(.debug_str): uncompress failed: zlib error: Z_DATA_ERROR

lld/test/ELF/compressed-debug-input.s

+8 −0
Original line number Diff line number Diff line 
# REQUIRES: zlib, x86



# RUN: llvm-mc -compress-debug-sections=zlib -filetype=obj -triple=x86_64-unknown-linux %s -o %t

# RUN: llvm-mc -compress-debug-sections=zlib -filetype=obj -triple=powerpc64-unknown-unknown %s -o %t-be

# RUN: llvm-readobj --sections %t | FileCheck -check-prefix=ZLIB %s

# RUN: llvm-readobj --sections %t-be | FileCheck -check-prefix=ZLIB %s

# ZLIB:      Section {

# ZLIB:        Index: 2

# ZLIB:        Name: .debug_str
@@ -21,7 +23,9 @@ 
# ZLIB-NEXT: }



# RUN: llvm-mc -compress-debug-sections=zlib-gnu -filetype=obj -triple=x86_64-unknown-linux %s -o %t2

# RUN: llvm-mc -compress-debug-sections=zlib-gnu -filetype=obj -triple=powerpc64-unknown-unknown %s -o %t2-be

# RUN: llvm-readobj --sections %t2 | FileCheck -check-prefix=GNU %s

# RUN: llvm-readobj --sections %t2-be | FileCheck -check-prefix=GNU %s

# GNU:      Section {

# GNU:        Index: 2

# GNU:        Name: .zdebug_str
@@ -41,9 +45,13 @@ 


# RUN: ld.lld --hash-style=sysv %t -o %t.so -shared

# RUN: llvm-readobj --sections --section-data %t.so | FileCheck -check-prefix=DATA %s

# RUN: ld.lld --hash-style=sysv %t-be -o %t-be.so -shared

# RUN: llvm-readobj --sections --section-data %t-be.so | FileCheck -check-prefix=DATA %s



# RUN: ld.lld --hash-style=sysv %t2 -o %t2.so -shared

# RUN: llvm-readobj --sections --section-data %t2.so | FileCheck -check-prefix=DATA %s

# RUN: ld.lld --hash-style=sysv %t2-be -o %t2-be.so -shared

# RUN: llvm-readobj --sections --section-data %t2-be.so | FileCheck -check-prefix=DATA %s



# DATA:      Section {

# DATA:        Index: 6