Index: llvm/lib/ObjectYAML/ELFEmitter.cpp =================================================================== --- llvm/lib/ObjectYAML/ELFEmitter.cpp +++ llvm/lib/ObjectYAML/ELFEmitter.cpp @@ -164,6 +164,9 @@ void finalizeStrings(); void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS); + void writeSectionContent(Elf_Shdr &SHeader, + const ELFYAML::NoBitsSection &Section, + ContiguousBlobAccumulator &CBA); void writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section, ContiguousBlobAccumulator &CBA); @@ -570,9 +573,7 @@ } else if (auto S = dyn_cast(Sec)) { writeSectionContent(SHeader, *S, CBA); } else if (auto S = dyn_cast(Sec)) { - // SHT_NOBITS sections do not have any content to write. - SHeader.sh_entsize = 0; - SHeader.sh_size = S->Size; + writeSectionContent(SHeader, *S, CBA); } else if (auto S = dyn_cast(Sec)) { writeSectionContent(SHeader, *S, CBA); } else if (auto S = dyn_cast(Sec)) { @@ -953,6 +954,34 @@ } } +static bool shouldAllocateFileSpace(ArrayRef Phdrs, + const ELFYAML::NoBitsSection &S) { + for (const ELFYAML::ProgramHeader &PH : Phdrs) { + auto It = llvm::find_if( + PH.Chunks, [&](ELFYAML::Chunk *C) { return C->Name == S.Name; }); + if (std::any_of(It, PH.Chunks.end(), [](ELFYAML::Chunk *C) { + return (isa(C) || + cast(C)->Type != ELF::SHT_NOBITS); + })) + return true; + } + return false; +} + +template +void ELFState::writeSectionContent(Elf_Shdr &SHeader, + const ELFYAML::NoBitsSection &S, + ContiguousBlobAccumulator &CBA) { + // SHT_NOBITS sections do not have any content to write. + SHeader.sh_entsize = 0; + SHeader.sh_size = S.Size; + + // When a nobits section is followed by a non-nobits section or fill in the + // same segment, we allocate the file space for it. + if (shouldAllocateFileSpace(Doc.ProgramHeaders, S)) + CBA.getOS().write_zeros(S.Size); +} + template void ELFState::writeSectionContent( Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section, Index: llvm/test/tools/llvm-objcopy/ELF/preserve-segment-contents.test =================================================================== --- llvm/test/tools/llvm-objcopy/ELF/preserve-segment-contents.test +++ llvm/test/tools/llvm-objcopy/ELF/preserve-segment-contents.test @@ -13,7 +13,7 @@ # RUN: llvm-objcopy %t.base %t.stripped --regex -R blob.* # Show that the removal leaves the bytes as zeroes, as desired, for all our # test cases. -# RUN: od -t x1 -j 0x2000 -N 24 %t.stripped | FileCheck %s --ignore-case --check-prefix=CHECK1 -DPATTERN="00 00 00 00" +# RUN: od -t x1 -j 0x2000 -N 28 %t.stripped | FileCheck %s --ignore-case --check-prefix=CHECK1 -DPATTERN="00 00 00 00" # RUN: od -t x1 -j 0x2100 -N 12 %t.stripped | FileCheck %s --ignore-case --check-prefix=CHECK2 -DPATTERN="00 00 00 00" # RUN: od -t x1 -j 0x2200 -N 4 %t.stripped | FileCheck %s --ignore-case --check-prefix=CHECK3 -DPATTERN="00 00 00 00" # RUN: od -t x1 -j 0x2300 -N 12 %t.stripped | FileCheck %s --ignore-case --check-prefix=CHECK4 -DPATTERN="00 00 00 00" @@ -24,7 +24,7 @@ # RUN: cp %t.stripped %t.in # RUN: echo "with open('%/t.in', 'rb+') as input:" > %t.py # RUN: echo " for offset in [" >> %t.py -# RUN: echo " 0x2000, 0x2008, 0x200C, 0x2014, 0x2104, 0x2300," >> %t.py +# RUN: echo " 0x2000, 0x2008, 0x200C, 0x2018, 0x2104, 0x2300," >> %t.py # RUN: echo " 0x3008, 0x3010, 0x3018, 0x3020, 0x3028, 0x302C, 0x3034, 0x303C," >> %t.py # RUN: echo " 0x4000, 0x4008, 0x4010, 0x4014, 0x401C, 0x4024, 0x4034," >> %t.py # RUN: echo " 0x5000, 0x5008, 0x5010, 0x501C, 0x5024, 0x502C, 0x5030, 0x5038]:" >> %t.py @@ -32,7 +32,7 @@ # RUN: echo " input.write(bytearray.fromhex('DEADBEEF'))" >> %t.py # RUN: %python %t.py # RUN: llvm-objcopy %t.in %t.out -# RUN: od -t x1 -j 0x2000 -N 24 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK1 -DPATTERN="de ad be ef" +# RUN: od -t x1 -j 0x2000 -N 28 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK1 -DPATTERN="de ad be ef" # RUN: od -t x1 -j 0x2100 -N 12 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK2 -DPATTERN="de ad be ef" # RUN: od -t x1 -j 0x2200 -N 4 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK3 -DPATTERN="de ad be ef" # RUN: od -t x1 -j 0x2300 -N 12 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK4 -DPATTERN="de ad be ef" @@ -41,7 +41,7 @@ # RUN: od -t x1 -j 0x5000 -N 60 %t.out | FileCheck %s --ignore-case --check-prefix=CHECK7 -DPATTERN="de ad be ef" # CHECK1: [[PATTERN]] 11 22 33 44 [[PATTERN]] [[PATTERN]] -# CHECK1-NEXT: 55 66 77 88 [[PATTERN]] +# CHECK1-NEXT: 00 00 00 00 55 66 77 88 [[PATTERN]] # CHECK2: 99 00 aa bb [[PATTERN]] cc dd ee ff # CHECK3: fe fe fe fe # CHECK4: [[PATTERN]] 00 00 00 00 00 00 00 00 Index: llvm/test/tools/yaml2obj/ELF/program-header-nobits.yaml =================================================================== --- llvm/test/tools/yaml2obj/ELF/program-header-nobits.yaml +++ llvm/test/tools/yaml2obj/ELF/program-header-nobits.yaml @@ -1,39 +1,142 @@ -# RUN: yaml2obj %s -o %t -# RUN: llvm-readobj -l %t | FileCheck %s +## In this test we check that we allocate file space for SHT_NOBITS sections when +## there are non-nobits sections in the same segment after them. When an object has +## multiple segments, we check each and allocate the space if at least one matches the +## condition mentioned. -!ELF +## Case A. In this case there are no non-nobits sections after SHT_NOBITS sections in segments. +## Because of this the file space for SHT_NOBITS sections is not allocated. +# RUN: yaml2obj %s -D SEC1=.data.before -D SEC2=.nobits.1 -o %t1 +# RUN: llvm-readelf --sections -l %t1 | FileCheck %s --check-prefix=NO-ALLOC + +# NO-ALLOC: [Nr] Name Type Address Off Size +# NO-ALLOC: [ 1] .data.before PROGBITS 0000000000000000 0000b0 000001 +# NO-ALLOC-NEXT: [ 2] .nobits.1 NOBITS 0000000000000001 0000b1 000002 +# NO-ALLOC-NEXT: [ 3] .data.after PROGBITS 0000000000000003 0000b1 000003 +# NO-ALLOC-NEXT: [ 4] .nobits.2 NOBITS 0000000000000006 0000b4 000004 +## .fill of size 0x5 is placed here. +# NO-ALLOC-NEXT: [ 5] .data.last PROGBITS 000000000000000f 0000b9 000006 + +# NO-ALLOC: Type Offset VirtAddr PhysAddr FileSiz MemSiz +# NO-ALLOC-NEXT: LOAD 0x0000b0 0x0000000000000000 0x0000000000000000 0x000001 0x000003 +# NO-ALLOC-NEXT: LOAD 0x0000b0 0x0000000000000000 0x0000000000000000 0x000001 0x000003 + +## Case B. We have a segment that has a non-nobits section after the SHT_NOBITS section ".nobits.1". +## The file space is allocated for it, but not for ".nobits.2", +## which does not belong to any segment. +# RUN: yaml2obj %s -D SEC1=.nobits.1 -D SEC2=.data.after -o %t2 +# RUN: llvm-readelf --sections -l %t2 | FileCheck %s --check-prefix=ALLOC-FIRST + +# ALLOC-FIRST: [Nr] Name Type Address Off Size +# ALLOC-FIRST: [ 1] .data.before PROGBITS 0000000000000000 0000b0 000001 +# ALLOC-FIRST-NEXT: [ 2] .nobits.1 NOBITS 0000000000000001 0000b1 000002 +# ALLOC-FIRST-NEXT: [ 3] .data.after PROGBITS 0000000000000003 0000b3 000003 +# ALLOC-FIRST-NEXT: [ 4] .nobits.2 NOBITS 0000000000000006 0000b6 000004 +## .fill of size 0x5 is placed here. +# ALLOC-FIRST-NEXT: [ 5] .data.last PROGBITS 000000000000000f 0000bb 000006 + +# ALLOC-FIRST: Type Offset VirtAddr PhysAddr FileSiz MemSiz +# ALLOC-FIRST-NEXT: LOAD 0x0000b0 0x0000000000000000 0x0000000000000000 0x000001 0x000003 +# ALLOC-FIRST-NEXT: LOAD 0x0000b1 0x0000000000000000 0x0000000000000000 0x000005 0x000005 + +## Case C. We have a Fill after the ".nobits.2" section. In this case the file space is +## allocated for it, because fills are handled just like any other non-nobits sections. +# RUN: yaml2obj %s -D SEC1=.nobits.2 -D SEC2=.fill -o %t3 +# RUN: llvm-readelf --sections -l %t3 | FileCheck %s --check-prefix=FILL-AT-END + +# FILL-AT-END: [Nr] Name Type Address Off Size +# FILL-AT-END: [ 4] .nobits.2 NOBITS 0000000000000006 0000b4 000004 +## .fill of size 0x5 is placed here. +# FILL-AT-END: [ 5] .data.last PROGBITS 000000000000000f 0000bd 000006 + +# FILL-AT-END: Type Offset VirtAddr PhysAddr FileSiz MemSiz +# FILL-AT-END-NEXT: LOAD 0x0000b0 0x0000000000000000 0x0000000000000000 0x000001 0x000003 +# FILL-AT-END-NEXT: LOAD 0x0000b4 0x0000000000000000 0x0000000000000000 0x000009 0x000009 + +--- !ELF +FileHeader: + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_EXEC + Machine: EM_X86_64 +Sections: + - Name: .data.before + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC ] + Size: 0x1 + - Name: .nobits.1 + Type: SHT_NOBITS + Flags: [ SHF_ALLOC ] + Size: 0x2 + - Name: .data.after + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC ] + Size: 0x3 + - Name: .nobits.2 + Type: SHT_NOBITS + Flags: [ SHF_ALLOC ] + Size: 0x4 + - Type: Fill + Name: .fill + Pattern: "00" + Size: 5 + - Name: .data.last + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC ] + Size: 0x6 +ProgramHeaders: +## We have 2 segments, the first is predefined and the second can be customized. +## We want to have more than one segment to show we check all of them when +## trying to find a non-nobits section after a nobits one. + - Type: PT_LOAD + Flags: [ PF_R ] + Sections: + - Section: .data.before + - Section: .nobits.1 + - Type: PT_LOAD + Flags: [ PF_R ] + Sections: + - Section: [[SEC1]] + - Section: [[SEC2]] + +## Case D. We have a segment with SHT_NOBITS sections on its borders and a one +## non-nobits in the middle. Check we allocate the file space only for +## the first nobits section. + +# RUN: yaml2obj --docnum=2 %s -o %t4 +# RUN: llvm-readelf --sections -l %t4 | FileCheck %s --check-prefix=MIDDLE + +# MIDDLE: [Nr] Name Type Address Off Size +# MIDDLE: [ 1] .nobits.1 NOBITS 0000000000000000 000078 000001 +# MIDDLE-NEXT: [ 2] .data PROGBITS 0000000000000001 000079 000010 +# MIDDLE-NEXT: [ 3] .nobits.2 NOBITS 0000000000000011 000089 000100 +# MIDDLE-NEXT: [ 4] .strtab STRTAB 0000000000000000 000089 000001 + +# MIDDLE: Type Offset VirtAddr PhysAddr FileSiz MemSiz +# MIDDLE: LOAD 0x000078 0x0000000000000000 0x0000000000000000 0x000011 0x000111 + +--- !ELF FileHeader: - Class: ELFCLASS64 - Data: ELFDATA2LSB - Type: ET_EXEC - Machine: EM_X86_64 + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_EXEC + Machine: EM_X86_64 Sections: - - Name: .data - Type: SHT_PROGBITS - Flags: [ SHF_ALLOC ] - Content: "00000000" - - Name: .after - Type: SHT_NOBITS - Flags: [ SHF_ALLOC ] - Size: 64 + - Name: .nobits.1 + Type: SHT_NOBITS + Flags: [ SHF_ALLOC ] + Size: 0x1 + - Name: .data + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC ] + Size: 0x10 + - Name: .nobits.2 + Type: SHT_NOBITS + Flags: [ SHF_ALLOC ] + Size: 0x100 ProgramHeaders: - - Type: PT_LOAD + - Type: PT_LOAD Flags: [ PF_R ] Sections: + - Section: .nobits.1 - Section: .data - - Section: .after - -#CHECK: ProgramHeaders [ -#CHECK-NEXT: ProgramHeader { -#CHECK-NEXT: Type: PT_LOAD -#CHECK-NEXT: Offset: -#CHECK-NEXT: VirtualAddress: -#CHECK-NEXT: PhysicalAddress: -#CHECK-NEXT: FileSize: 4 -#CHECK-NEXT: MemSize: 68 -#CHECK-NEXT: Flags [ -#CHECK-NEXT: PF_R -#CHECK-NEXT: ] -#CHECK-NEXT: Alignment: -#CHECK-NEXT: } -#CHECK-NEXT:] + - Section: .nobits.2