From 691d967bcc308f633209e45b646074b4e40e53ce Mon Sep 17 00:00:00 2001 From: George Rimar Date: Wed, 18 Jul 2018 08:19:58 +0000 Subject: [PATCH] [llvm-readobj] - Teach tool to dump objects with >= SHN_LORESERVE of sections. http://www.sco.com/developers/gabi/2003-12-17/ch4.eheader.html says that e_shnum and/or e_shstrndx may have special values if "the number of sections is greater than or equal to SHN_LORESERVE" or "the section name string table section index is greater than or equal to SHN_LORESERVE (0xff00)" Previously llvm-readobj was unable to dump such files, patch changes that. I had to add a precompiled test case because it does not seem possible to prepare a test using yaml2obj or llvm-mc (not clear how to make .shstrtab to have index >= SHN_LORESERVE). Differential revision: https://reviews.llvm.org/D49369 llvm-svn: 337360 --- .../Inputs/many-sections-stripped.elf-x86_64 | Bin 0 -> 504 bytes .../Inputs/many-sections.elf-x86_64 | Bin 0 -> 504 bytes test/tools/llvm-readobj/many-sections.s | 36 ++++++++++++++++++ tools/llvm-readobj/ELFDumper.cpp | 32 ++++++++++++++-- 4 files changed, 64 insertions(+), 4 deletions(-) create mode 100644 test/tools/llvm-readobj/Inputs/many-sections-stripped.elf-x86_64 create mode 100644 test/tools/llvm-readobj/Inputs/many-sections.elf-x86_64 create mode 100644 test/tools/llvm-readobj/many-sections.s diff --git a/test/tools/llvm-readobj/Inputs/many-sections-stripped.elf-x86_64 b/test/tools/llvm-readobj/Inputs/many-sections-stripped.elf-x86_64 new file mode 100644 index 0000000000000000000000000000000000000000..a589dc5d6a9c5ed4ea6c4d2d1e04179ebc4f43c0 GIT binary patch literal 504 zcmb<-^>JfjWMqH=Mg}_u1P>;PN;`nLAoBlzFcSyCjKw67*#cO^8T3k0D@qvjiYs$V z5|e;*MsZ0Igax4);)_cXi%M`0b#|1hWsO2VFk^I$RW4 literal 0 HcmV?d00001 diff --git a/test/tools/llvm-readobj/Inputs/many-sections.elf-x86_64 b/test/tools/llvm-readobj/Inputs/many-sections.elf-x86_64 new file mode 100644 index 0000000000000000000000000000000000000000..1abb98a01b845630a8b8f5b20410da22bda9f330 GIT binary patch literal 504 zcmb<-^>JfjWMqH=Mg}_u1P><4z_0_sWN-kpLFE7cU?vWN8H-6Evjwn-Gw7A1R+KR4 z6<6k#BqjmrjN+0a2n#|p#21$&7M0+z3PYF`D#DB*0}%kZ1BBVorXFfI#>0j1f2 zG!vQ_i0c3q^MKMIeIRulP`(6|<_FT)+|~h=SA^0q3glK~APMAP)4vj`2xcEl54wH; DhwBv) literal 0 HcmV?d00001 diff --git a/test/tools/llvm-readobj/many-sections.s b/test/tools/llvm-readobj/many-sections.s new file mode 100644 index 00000000000..383df266139 --- /dev/null +++ b/test/tools/llvm-readobj/many-sections.s @@ -0,0 +1,36 @@ +## many-sections.elf-x86_64 is a file that was generated to simulate +## an object with more than ~65k sections. When an ELF object +## has SHN_LORESERVE (0xff00) or more sections, its e_shnum field +## should be zero and sh_size of the section header at index 0 is used +## to store the value. If the section name string table section index is +## greater than or equal to SHN_LORESERVE, then e_shstrndx field +## should have the value of SHN_XINDEX and sh_link of the section header +## at index 0 is used to store the value. +## +## many-sections.elf-x86_64 has few sections to save disk +## space, but its e_shnum, e_shstrndx, sh_size and sh_link fields are set +## according to the above description, so that we can test the dumper. + +# RUN: llvm-readobj -file-headers -elf-output-style GNU \ +# RUN: %p/Inputs/many-sections.elf-x86_64 | FileCheck %s --check-prefix=GNU1 +# GNU1: Number of section headers: 0 (5) +# GNU1: Section header string table index: 65535 (3) + +# RUN: llvm-readobj -file-headers -elf-output-style LLVM \ +# RUN: %p/Inputs/many-sections.elf-x86_64 | FileCheck %s --check-prefix=LLVM1 +# LLVM1: SectionHeaderCount: 0 (5) +# LLVM1: StringTableSectionIndex: 65535 (3) + +## many-sections-stripped.elf-x86_64 is many-sections.elf-x86_64 with +## e_shoff field set to zero, but not e_shstrndx, to show that +## this corrupt case is handled correctly. + +# RUN: llvm-readobj -file-headers -elf-output-style GNU \ +# RUN: %p/Inputs/many-sections-stripped.elf-x86_64 | FileCheck %s --check-prefix=GNU2 +# GNU2: Number of section headers: 0 +# GNU2: Section header string table index: 65535 (corrupt: out of range) + +# RUN: llvm-readobj -file-headers -elf-output-style LLVM \ +# RUN: %p/Inputs/many-sections-stripped.elf-x86_64 | FileCheck %s --check-prefix=LLVM2 +# LLVM2: SectionHeaderCount: 0 +# LLVM2: StringTableSectionIndex: 65535 (corrupt: out of range) diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp index 130c19cc888..db551de274f 100644 --- a/tools/llvm-readobj/ELFDumper.cpp +++ b/tools/llvm-readobj/ELFDumper.cpp @@ -2486,6 +2486,30 @@ static inline void printFields(formatted_raw_ostream &OS, StringRef Str1, OS.flush(); } +template +static std::string getSectionHeadersNumString(const ELFFile *Obj) { + const typename ELFT::Ehdr *ElfHeader = Obj->getHeader(); + if (ElfHeader->e_shnum != 0) + return to_string(ElfHeader->e_shnum); + + ArrayRef Arr = unwrapOrError(Obj->sections()); + if (Arr.empty()) + return "0"; + return "0 (" + to_string(Arr[0].sh_size) + ")"; +} + +template +static std::string getSectionHeaderTableIndexString(const ELFFile *Obj) { + const typename ELFT::Ehdr *ElfHeader = Obj->getHeader(); + if (ElfHeader->e_shstrndx != SHN_XINDEX) + return to_string(ElfHeader->e_shstrndx); + + ArrayRef Arr = unwrapOrError(Obj->sections()); + if (Arr.empty()) + return "65535 (corrupt: out of range)"; + return to_string(ElfHeader->e_shstrndx) + " (" + to_string(Arr[0].sh_link) + ")"; +} + template void GNUStyle::printFileHeaders(const ELFO *Obj) { const Elf_Ehdr *e = Obj->getHeader(); OS << "ELF Header:\n"; @@ -2531,9 +2555,9 @@ template void GNUStyle::printFileHeaders(const ELFO *Obj) { printFields(OS, "Number of program headers:", Str); Str = to_string(e->e_shentsize) + " (bytes)"; printFields(OS, "Size of section headers:", Str); - Str = to_string(e->e_shnum); + Str = getSectionHeadersNumString(Obj); printFields(OS, "Number of section headers:", Str); - Str = to_string(e->e_shstrndx); + Str = getSectionHeaderTableIndexString(Obj); printFields(OS, "Section header string table index:", Str); } @@ -4019,8 +4043,8 @@ template void LLVMStyle::printFileHeaders(const ELFO *Obj) { W.printNumber("ProgramHeaderEntrySize", e->e_phentsize); W.printNumber("ProgramHeaderCount", e->e_phnum); W.printNumber("SectionHeaderEntrySize", e->e_shentsize); - W.printNumber("SectionHeaderCount", e->e_shnum); - W.printNumber("StringTableSectionIndex", e->e_shstrndx); + W.printString("SectionHeaderCount", getSectionHeadersNumString(Obj)); + W.printString("StringTableSectionIndex", getSectionHeaderTableIndexString(Obj)); } }