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[obj2yaml] - Teach tool to emit the "SectionHeaderTable" key and sort…
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… sections by file offset.

Currently when we dump sections, we dump them in the order,
which is specified in the sections header table.

With that the order in the output might not match the order in the file.
This patch starts sorting them by by file offsets when dumping.

When the order in the section header table doesn't match the order
in the file, we should emit the "SectionHeaderTable" key. This patch does it.

Differential revision: https://reviews.llvm.org/D91249
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Georgii Rymar committed Dec 1, 2020
1 parent 398b729 commit ea8c8a5
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Showing 5 changed files with 153 additions and 71 deletions.
2 changes: 1 addition & 1 deletion llvm/lib/ObjectYAML/ELFYAML.cpp
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Expand Up @@ -1648,12 +1648,12 @@ void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
IO.setContext(&Object);
IO.mapTag("!ELF", true);
IO.mapRequired("FileHeader", Object.Header);
IO.mapOptional("SectionHeaderTable", Object.SectionHeaders);
IO.mapOptional("ProgramHeaders", Object.ProgramHeaders);
IO.mapOptional("Sections", Object.Chunks);
IO.mapOptional("Symbols", Object.Symbols);
IO.mapOptional("DynamicSymbols", Object.DynamicSymbols);
IO.mapOptional("DWARF", Object.DWARF);
IO.mapOptional("SectionHeaderTable", Object.SectionHeaders);
if (Object.DWARF) {
Object.DWARF->IsLittleEndian =
Object.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
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8 changes: 4 additions & 4 deletions llvm/test/Object/X86/obj2yaml-dup-section-name.s
View file
Expand Up @@ -2,18 +2,18 @@
# RUN: obj2yaml %t.o | FileCheck %s

# CHECK: Sections:
# CHECK: - Name: .text.foo{{$}}
# CHECK: - Name: '.text.foo (1)'
# CHECK: - Name: .group{{$}}
# CHECK: Members:
# CHECK: - SectionOrType: .text.foo{{$}}
# CHECK: - SectionOrType: .rela.text.foo{{$}}
# CHECK: - Name: .text.foo{{$}}
# CHECK: - Name: .rela.text.foo{{$}}
# CHECK: Info: .text.foo{{$}}
# CHECK: - Name: '.group (1)'
# CHECK: Members:
# CHECK: - SectionOrType: '.text.foo (1)'
# CHECK: - SectionOrType: '.rela.text.foo (1)'
# CHECK: - Name: '.text.foo (1)'
# CHECK: - Name: .rela.text.foo{{$}}
# CHECK: Info: .text.foo{{$}}
# CHECK: - Name: '.rela.text.foo (1)'
# CHECK: Info: '.text.foo (1)'
# CHECK: Symbols:
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92 changes: 57 additions & 35 deletions llvm/test/Object/obj2yaml.test
View file
Expand Up @@ -358,35 +358,10 @@
# ELF-MIPSEL-NEXT: Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
# ELF-MIPSEL-NEXT: AddressAlign: 0x4
# ELF-MIPSEL-NEXT: Content: 0000023C00004224E8FFBD271400BFAF1000B0AF218059000000018E000024240000198E09F8200321E000020000198E09F8200321E00002000002241000B08F1400BF8F0800E0031800BD27
# ELF-MIPSEL-NEXT: - Name: .rel.text
# ELF-MIPSEL-NEXT: Type: SHT_REL
# ELF-MIPSEL-NEXT: Link: .symtab
# ELF-MIPSEL-NEXT: AddressAlign: 0x4
# ELF-MIPSEL-NEXT: Offset: 0x434
# ELF-MIPSEL-NEXT: Info: .text
# ELF-MIPSEL-NEXT: Relocations:
# ELF-MIPSEL-NEXT: - Symbol: _gp_disp
# ELF-MIPSEL-NEXT: Type: R_MIPS_HI16
# ELF-MIPSEL-NEXT: - Offset: 0x4
# ELF-MIPSEL-NEXT: Symbol: _gp_disp
# ELF-MIPSEL-NEXT: Type: R_MIPS_LO16
# ELF-MIPSEL-NEXT: - Offset: 0x18
# ELF-MIPSEL-NEXT: Symbol: '$.str'
# ELF-MIPSEL-NEXT: Type: R_MIPS_GOT16
# ELF-MIPSEL-NEXT: - Offset: 0x1C
# ELF-MIPSEL-NEXT: Symbol: '$.str'
# ELF-MIPSEL-NEXT: Type: R_MIPS_LO16
# ELF-MIPSEL-NEXT: - Offset: 0x20
# ELF-MIPSEL-NEXT: Symbol: puts
# ELF-MIPSEL-NEXT: Type: R_MIPS_CALL16
# ELF-MIPSEL-NEXT: - Offset: 0x2C
# ELF-MIPSEL-NEXT: Symbol: SomeOtherFunction
# ELF-MIPSEL-NEXT: Type: R_MIPS_CALL16
# ELF-MIPSEL-NEXT: - Name: .data
# ELF-MIPSEL-NEXT: Type: SHT_PROGBITS
# ELF-MIPSEL-NEXT: Flags: [ SHF_WRITE, SHF_ALLOC ]
# ELF-MIPSEL-NEXT: AddressAlign: 0x4
# ELF-MIPSEL-NEXT: Offset: 0x80
# ELF-MIPSEL-NEXT: - Name: .bss
# ELF-MIPSEL-NEXT: Type: SHT_NOBITS
# ELF-MIPSEL-NEXT: Flags: [ SHF_WRITE, SHF_ALLOC ]
Expand Down Expand Up @@ -416,6 +391,29 @@
# ELF-MIPSEL-NEXT: GPRSize: REG_32
# ELF-MIPSEL-NEXT: CPR1Size: REG_32
# ELF-MIPSEL-NEXT: Flags1: [ ODDSPREG ]
# ELF-MIPSEL-NEXT: - Name: .rel.text
# ELF-MIPSEL-NEXT: Type: SHT_REL
# ELF-MIPSEL-NEXT: Link: .symtab
# ELF-MIPSEL-NEXT: AddressAlign: 0x4
# ELF-MIPSEL-NEXT: Info: .text
# ELF-MIPSEL-NEXT: Relocations:
# ELF-MIPSEL-NEXT: - Symbol: _gp_disp
# ELF-MIPSEL-NEXT: Type: R_MIPS_HI16
# ELF-MIPSEL-NEXT: - Offset: 0x4
# ELF-MIPSEL-NEXT: Symbol: _gp_disp
# ELF-MIPSEL-NEXT: Type: R_MIPS_LO16
# ELF-MIPSEL-NEXT: - Offset: 0x18
# ELF-MIPSEL-NEXT: Symbol: '$.str'
# ELF-MIPSEL-NEXT: Type: R_MIPS_GOT16
# ELF-MIPSEL-NEXT: - Offset: 0x1C
# ELF-MIPSEL-NEXT: Symbol: '$.str'
# ELF-MIPSEL-NEXT: Type: R_MIPS_LO16
# ELF-MIPSEL-NEXT: - Offset: 0x20
# ELF-MIPSEL-NEXT: Symbol: puts
# ELF-MIPSEL-NEXT: Type: R_MIPS_CALL16
# ELF-MIPSEL-NEXT: - Offset: 0x2C
# ELF-MIPSEL-NEXT: Symbol: SomeOtherFunction
# ELF-MIPSEL-NEXT: Type: R_MIPS_CALL16
# ELF-MIPSEL-NEXT: Symbols:
# ELF-MIPSEL-NEXT: - Name: trivial.ll
# ELF-MIPSEL-NEXT: Type: STT_FILE
Expand Down Expand Up @@ -461,6 +459,20 @@
# ELF-MIPSEL-NEXT: Binding: STB_GLOBAL
# ELF-MIPSEL-NEXT: - Name: puts
# ELF-MIPSEL-NEXT: Binding: STB_GLOBAL
# ELF-MIPSEL-NEXT: SectionHeaderTable:
# ELF-MIPSEL-NEXT: Sections:
# ELF-MIPSEL-NEXT: - Name: .text
# ELF-MIPSEL-NEXT: - Name: .rel.text
# ELF-MIPSEL-NEXT: - Name: .data
# ELF-MIPSEL-NEXT: - Name: .bss
# ELF-MIPSEL-NEXT: - Name: .mdebug.abi32
# ELF-MIPSEL-NEXT: - Name: .rodata.str1.1
# ELF-MIPSEL-NEXT: - Name: .reginfo
# ELF-MIPSEL-NEXT: - Name: .MIPS.abiflags
# ELF-MIPSEL-NEXT: - Name: .shstrtab
# ELF-MIPSEL-NEXT: - Name: .symtab
# ELF-MIPSEL-NEXT: - Name: .strtab
# ELF-MIPSEL-NEXT: ...

# RUN: obj2yaml %p/Inputs/trivial-object-test.elf-mips64el | FileCheck %s --check-prefix ELF-MIPS64EL

Expand All @@ -480,20 +492,10 @@
# ELF-MIPS64EL-NEXT: Flags: [ SHF_WRITE, SHF_ALLOC ]
# ELF-MIPS64EL-NEXT: AddressAlign: 0x10
# ELF-MIPS64EL-NEXT: Content: '00000000000000000000000000000000'
# ELF-MIPS64EL-NEXT: - Name: .rela.data
# ELF-MIPS64EL-NEXT: Type: SHT_RELA
# ELF-MIPS64EL-NEXT: Link: .symtab
# ELF-MIPS64EL-NEXT: AddressAlign: 0x8
# ELF-MIPS64EL-NEXT: Offset: 0x410
# ELF-MIPS64EL-NEXT: Info: .data
# ELF-MIPS64EL-NEXT: Relocations:
# ELF-MIPS64EL-NEXT: - Symbol: zed
# ELF-MIPS64EL-NEXT: Type: R_MIPS_64
# ELF-MIPS64EL-NEXT: - Name: .bss
# ELF-MIPS64EL-NEXT: Type: SHT_NOBITS
# ELF-MIPS64EL-NEXT: Flags: [ SHF_WRITE, SHF_ALLOC ]
# ELF-MIPS64EL-NEXT: AddressAlign: 0x10
# ELF-MIPS64EL-NEXT: Offset: 0x50
# ELF-MIPS64EL-NEXT: - Name: .MIPS.options
# ELF-MIPS64EL-NEXT: Type: SHT_MIPS_OPTIONS
# ELF-MIPS64EL-NEXT: Flags: [ SHF_ALLOC, SHF_MIPS_NOSTRIP ]
Expand All @@ -503,6 +505,14 @@
# ELF-MIPS64EL-NEXT: - Name: .pdr
# ELF-MIPS64EL-NEXT: Type: SHT_PROGBITS
# ELF-MIPS64EL-NEXT: AddressAlign: 0x4
# ELF-MIPS64EL-NEXT: - Name: .rela.data
# ELF-MIPS64EL-NEXT: Type: SHT_RELA
# ELF-MIPS64EL-NEXT: Link: .symtab
# ELF-MIPS64EL-NEXT: AddressAlign: 0x8
# ELF-MIPS64EL-NEXT: Info: .data
# ELF-MIPS64EL-NEXT: Relocations:
# ELF-MIPS64EL-NEXT: - Symbol: zed
# ELF-MIPS64EL-NEXT: Type: R_MIPS_64
# ELF-MIPS64EL-NEXT: Symbols:
# ELF-MIPS64EL-NEXT: - Name: .text
# ELF-MIPS64EL-NEXT: Type: STT_SECTION
Expand All @@ -523,6 +533,18 @@
# ELF-MIPS64EL-NEXT: Section: .pdr
# ELF-MIPS64EL-NEXT: - Name: zed
# ELF-MIPS64EL-NEXT: Binding: STB_GLOBAL
# ELF-MIPS64EL-NEXT: SectionHeaderTable:
# ELF-MIPS64EL-NEXT: Sections:
# ELF-MIPS64EL-NEXT: - Name: .text
# ELF-MIPS64EL-NEXT: - Name: .data
# ELF-MIPS64EL-NEXT: - Name: .rela.data
# ELF-MIPS64EL-NEXT: - Name: .bss
# ELF-MIPS64EL-NEXT: - Name: .MIPS.options
# ELF-MIPS64EL-NEXT: - Name: .pdr
# ELF-MIPS64EL-NEXT: - Name: .shstrtab
# ELF-MIPS64EL-NEXT: - Name: .symtab
# ELF-MIPS64EL-NEXT: - Name: .strtab
# ELF-MIPS64EL-NEXT: ...

# RUN: yaml2obj %s -o %t-x86-64
# RUN: obj2yaml %t-x86-64 | FileCheck %s --check-prefix ELF-X86-64
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93 changes: 62 additions & 31 deletions llvm/test/tools/obj2yaml/ELF/offset.yaml
View file
Expand Up @@ -5,37 +5,49 @@
# RUN: yaml2obj %s -o %t1.o
# RUN: obj2yaml %t1.o | FileCheck %s --check-prefix=BASIC

# BASIC: --- !ELF
# BASIC-NEXT: FileHeader:
# BASIC-NEXT: Class: ELFCLASS64
# BASIC-NEXT: Data: ELFDATA2LSB
# BASIC-NEXT: Type: ET_REL
# BASIC-NEXT: Sections:
# BASIC-NEXT: - Name: .foo1
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .foo2
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .foo3
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar1
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Offset: 0x100
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar2
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x10
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar3
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x10
# BASIC-NEXT: Offset: 0x200
# BASIC-NEXT: - Name: .bar4
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x100000000
# BASIC-NEXT: Offset: 0x210
# BASIC: --- !ELF
# BASIC-NEXT: FileHeader:
# BASIC-NEXT: Class: ELFCLASS64
# BASIC-NEXT: Data: ELFDATA2LSB
# BASIC-NEXT: Type: ET_REL
# BASIC-NEXT: Sections:
# BASIC-NEXT: - Name: .foo1
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .foo2
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .foo3
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar1
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: Offset: 0x100
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar2
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x10
# BASIC-NEXT: Content: '00'
# BASIC-NEXT: - Name: .bar3
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x10
# BASIC-NEXT: Offset: 0x200
# BASIC-NEXT: - Name: .bar4
# BASIC-NEXT: Type: SHT_PROGBITS
# BASIC-NEXT: AddressAlign: 0x100000000
# BASIC-NEXT: Offset: 0x210
# HEADERS-NEXT: SectionHeaderTable:
# HEADERS-NEXT: Sections:
# HEADERS-NEXT: - Name: .bar4
# HEADERS-NEXT: - Name: .bar3
# HEADERS-NEXT: - Name: .bar2
# HEADERS-NEXT: - Name: .bar1
# HEADERS-NEXT: - Name: .foo3
# HEADERS-NEXT: - Name: .foo2
# HEADERS-NEXT: - Name: .foo1
# HEADERS-NEXT: - Name: .strtab
# HEADERS-NEXT: - Name: .shstrtab
# BASIC-NEXT: ...

--- !ELF
FileHeader:
Expand Down Expand Up @@ -91,6 +103,25 @@ Sections:
Type: SHT_PROGBITS
AddressAlign: 0x100000000
Offset: 0x210
SectionHeaderTable:
Sections:
## By default we have the same order of sections as defined by the "Sections" key.
- Name: [[SEC1=.foo1]]
- Name: [[SEC2=.foo2]]
- Name: [[SEC3=.foo3]]
- Name: [[SEC4=.bar1]]
- Name: [[SEC5=.bar2]]
- Name: [[SEC6=.bar3]]
- Name: [[SEC7=.bar4]]
- Name: .strtab
- Name: .shstrtab

## In this case we change the order of sections in the section header table.
## Check that we still dump offsets correctly.

# RUN: yaml2obj %s -DSEC1=.bar4 -DSEC2=.bar3 -DSEC3=.bar2 \
# RUN: -DSEC4=.bar1 -DSEC5=.foo3 -DSEC6=.foo2 -DSEC7=.foo1 -o %t1-sechdr.o
# RUN: obj2yaml %t1-sechdr.o | FileCheck --check-prefixes=BASIC,HEADERS %s

## Show we dump the "Offset" key for the first section when
## it has an unexpected file offset.
Expand Down
29 changes: 29 additions & 0 deletions llvm/tools/obj2yaml/elf2yaml.cpp
View file
Expand Up @@ -359,6 +359,20 @@ template <class ELFT> Expected<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
return ChunksOrErr.takeError();
std::vector<std::unique_ptr<ELFYAML::Chunk>> Chunks = std::move(*ChunksOrErr);

std::vector<ELFYAML::Section *> OriginalOrder;
if (!Chunks.empty())
for (const std::unique_ptr<ELFYAML::Chunk> &C :
makeArrayRef(Chunks).drop_front())
OriginalOrder.push_back(cast<ELFYAML::Section>(C.get()));

// Sometimes the order of sections in the section header table does not match
// their actual order. Here we sort sections by the file offset.
llvm::stable_sort(Chunks, [&](const std::unique_ptr<ELFYAML::Chunk> &A,
const std::unique_ptr<ELFYAML::Chunk> &B) {
return Sections[cast<ELFYAML::Section>(A.get())->OriginalSecNdx].sh_offset <
Sections[cast<ELFYAML::Section>(B.get())->OriginalSecNdx].sh_offset;
});

// Dump program headers.
Expected<std::vector<ELFYAML::ProgramHeader>> PhdrsOrErr =
dumpProgramHeaders(Chunks);
Expand All @@ -372,6 +386,21 @@ template <class ELFT> Expected<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
// Dump DWARF sections.
Y->DWARF = dumpDWARFSections(Chunks);

// We emit the "SectionHeaderTable" key when the order of sections in the
// sections header table doesn't match the file order.
const bool SectionsSorted =
llvm::is_sorted(Chunks, [&](const std::unique_ptr<ELFYAML::Chunk> &A,
const std::unique_ptr<ELFYAML::Chunk> &B) {
return cast<ELFYAML::Section>(A.get())->OriginalSecNdx <
cast<ELFYAML::Section>(B.get())->OriginalSecNdx;
});
if (!SectionsSorted) {
Y->SectionHeaders.emplace();
Y->SectionHeaders->Sections.emplace();
for (ELFYAML::Section *S : OriginalOrder)
Y->SectionHeaders->Sections->push_back({S->Name});
}

llvm::erase_if(Chunks, [this, &Y](const std::unique_ptr<ELFYAML::Chunk> &C) {
const ELFYAML::Section &S = cast<ELFYAML::Section>(*C.get());
return !shouldPrintSection(S, Sections[S.OriginalSecNdx], Y->DWARF);
Expand Down

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