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author | David Meyer <pdox@google.com> | 2012-03-09 20:59:52 +0000 |
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committer | David Meyer <pdox@google.com> | 2012-03-09 20:59:52 +0000 |
commit | 2d70e263c2b508bf4641273dd89a23149f6f6164 (patch) | |
tree | 73c16d556e0036179e38acac5d96621d8ddda23b /include/llvm/Object | |
parent | 6f9489a86f33624f9ff5388411d12359ce9cef20 (diff) | |
download | external_llvm-2d70e263c2b508bf4641273dd89a23149f6f6164.zip external_llvm-2d70e263c2b508bf4641273dd89a23149f6f6164.tar.gz external_llvm-2d70e263c2b508bf4641273dd89a23149f6f6164.tar.bz2 |
Support reading GNU symbol versions in ELFObjectFile
* Add enums and structures for GNU version information.
* Implement extraction of that information on a per-symbol basis (ELFObjectFile::getSymbolVersion).
* Implement a generic interface, GetELFSymbolVersion(), for getting the symbol version from the ObjectFile (hides the templating).
* Have llvm-readobj print out the version, when available.
* Add a test for the new feature: readobj-elf-versioning.test
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152436 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include/llvm/Object')
-rw-r--r-- | include/llvm/Object/ELF.h | 369 |
1 files changed, 360 insertions, 9 deletions
diff --git a/include/llvm/Object/ELF.h b/include/llvm/Object/ELF.h index e27a23e..d33f317 100644 --- a/include/llvm/Object/ELF.h +++ b/include/llvm/Object/ELF.h @@ -18,6 +18,7 @@ #include "llvm/ADT/StringSwitch.h" #include "llvm/ADT/Triple.h" #include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/PointerIntPair.h" #include "llvm/Object/ObjectFile.h" #include "llvm/Support/Casting.h" #include "llvm/Support/ELF.h" @@ -176,7 +177,72 @@ struct Elf_Sym_Impl : Elf_Sym_Base<target_endianness, is64Bits> { } }; -// Elf_Dyn: Entry in the dynamic table +/// Elf_Versym: This is the structure of entries in the SHT_GNU_versym section +/// (.gnu.version). This structure is identical for ELF32 and ELF64. +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Versym_Impl { + LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) + Elf_Half vs_index; // Version index with flags (e.g. VERSYM_HIDDEN) +}; + +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Verdaux_Impl; + +/// Elf_Verdef: This is the structure of entries in the SHT_GNU_verdef section +/// (.gnu.version_d). This structure is identical for ELF32 and ELF64. +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Verdef_Impl { + LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) + typedef Elf_Verdaux_Impl<target_endianness, is64Bits> Elf_Verdaux; + Elf_Half vd_version; // Version of this structure (e.g. VER_DEF_CURRENT) + Elf_Half vd_flags; // Bitwise flags (VER_DEF_*) + Elf_Half vd_ndx; // Version index, used in .gnu.version entries + Elf_Half vd_cnt; // Number of Verdaux entries + Elf_Word vd_hash; // Hash of name + Elf_Word vd_aux; // Offset to the first Verdaux entry (in bytes) + Elf_Word vd_next; // Offset to the next Verdef entry (in bytes) + + /// Get the first Verdaux entry for this Verdef. + const Elf_Verdaux *getAux() const { + return reinterpret_cast<const Elf_Verdaux*>((const char*)this + vd_aux); + } +}; + +/// Elf_Verdaux: This is the structure of auxilary data in the SHT_GNU_verdef +/// section (.gnu.version_d). This structure is identical for ELF32 and ELF64. +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Verdaux_Impl { + LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) + Elf_Word vda_name; // Version name (offset in string table) + Elf_Word vda_next; // Offset to next Verdaux entry (in bytes) +}; + +/// Elf_Verneed: This is the structure of entries in the SHT_GNU_verneed +/// section (.gnu.version_r). This structure is identical for ELF32 and ELF64. +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Verneed_Impl { + LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) + Elf_Half vn_version; // Version of this structure (e.g. VER_NEED_CURRENT) + Elf_Half vn_cnt; // Number of associated Vernaux entries + Elf_Word vn_file; // Library name (string table offset) + Elf_Word vn_aux; // Offset to first Vernaux entry (in bytes) + Elf_Word vn_next; // Offset to next Verneed entry (in bytes) +}; + +/// Elf_Vernaux: This is the structure of auxiliary data in SHT_GNU_verneed +/// section (.gnu.version_r). This structure is identical for ELF32 and ELF64. +template<support::endianness target_endianness, bool is64Bits> +struct Elf_Vernaux_Impl { + LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) + Elf_Word vna_hash; // Hash of dependency name + Elf_Half vna_flags; // Bitwise Flags (VER_FLAG_*) + Elf_Half vna_other; // Version index, used in .gnu.version entries + Elf_Word vna_name; // Dependency name + Elf_Word vna_next; // Offset to next Vernaux entry (in bytes) +}; + +/// Elf_Dyn_Base: This structure matches the form of entries in the dynamic +/// table section (.dynamic) look like. template<support::endianness target_endianness, bool is64Bits> struct Elf_Dyn_Base; @@ -200,6 +266,7 @@ struct Elf_Dyn_Base<target_endianness, true> { } d_un; }; +/// Elf_Dyn_Impl: This inherits from Elf_Dyn_Base, adding getters and setters. template<support::endianness target_endianness, bool is64Bits> struct Elf_Dyn_Impl : Elf_Dyn_Base<target_endianness, is64Bits> { using Elf_Dyn_Base<target_endianness, is64Bits>::d_tag; @@ -323,6 +390,11 @@ class ELFObjectFile : public ObjectFile { typedef Elf_Dyn_Impl<target_endianness, is64Bits> Elf_Dyn; typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel; typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela; + typedef Elf_Verdef_Impl<target_endianness, is64Bits> Elf_Verdef; + typedef Elf_Verdaux_Impl<target_endianness, is64Bits> Elf_Verdaux; + typedef Elf_Verneed_Impl<target_endianness, is64Bits> Elf_Verneed; + typedef Elf_Vernaux_Impl<target_endianness, is64Bits> Elf_Vernaux; + typedef Elf_Versym_Impl<target_endianness, is64Bits> Elf_Versym; typedef DynRefImpl<target_endianness, is64Bits> DynRef; typedef content_iterator<DynRef> dyn_iterator; @@ -364,15 +436,48 @@ private: const Elf_Shdr *dot_shstrtab_sec; // Section header string table. const Elf_Shdr *dot_strtab_sec; // Symbol header string table. const Elf_Shdr *dot_dynstr_sec; // Dynamic symbol string table. + + // SymbolTableSections[0] always points to the dynamic string table section + // header, or NULL if there is no dynamic string table. Sections_t SymbolTableSections; IndexMap_t SymbolTableSectionsIndexMap; DenseMap<const Elf_Sym*, ELF::Elf64_Word> ExtendedSymbolTable; - const Elf_Shdr *dot_dynamic_sec; // .dynamic + const Elf_Shdr *dot_dynamic_sec; // .dynamic + const Elf_Shdr *dot_gnu_version_sec; // .gnu.version + const Elf_Shdr *dot_gnu_version_r_sec; // .gnu.version_r + const Elf_Shdr *dot_gnu_version_d_sec; // .gnu.version_d + // Pointer to SONAME entry in dynamic string table // This is set the first time getLoadName is called. mutable const char *dt_soname; + // Records for each version index the corresponding Verdef or Vernaux entry. + // This is filled the first time LoadVersionMap() is called. + class VersionMapEntry : public PointerIntPair<const void*, 1> { + public: + // If the integer is 0, this is an Elf_Verdef*. + // If the integer is 1, this is an Elf_Vernaux*. + VersionMapEntry() : PointerIntPair<const void*, 1>(NULL, 0) { } + VersionMapEntry(const Elf_Verdef *verdef) + : PointerIntPair<const void*, 1>(verdef, 0) { } + VersionMapEntry(const Elf_Vernaux *vernaux) + : PointerIntPair<const void*, 1>(vernaux, 1) { } + bool isNull() const { return getPointer() == NULL; } + bool isVerdef() const { return !isNull() && getInt() == 0; } + bool isVernaux() const { return !isNull() && getInt() == 1; } + const Elf_Verdef *getVerdef() const { + return isVerdef() ? (const Elf_Verdef*)getPointer() : NULL; + } + const Elf_Vernaux *getVernaux() const { + return isVernaux() ? (const Elf_Vernaux*)getPointer() : NULL; + } + }; + mutable SmallVector<VersionMapEntry, 16> VersionMap; + void LoadVersionDefs(const Elf_Shdr *sec) const; + void LoadVersionNeeds(const Elf_Shdr *ec) const; + void LoadVersionMap() const; + /// @brief Map sections to an array of relocation sections that reference /// them sorted by section index. RelocMap_t SectionRelocMap; @@ -396,6 +501,10 @@ private: error_code getSymbolName(const Elf_Shdr *section, const Elf_Sym *Symb, StringRef &Res) const; + error_code getSymbolVersion(const Elf_Shdr *section, + const Elf_Sym *Symb, + StringRef &Version, + bool &IsDefault) const; void VerifyStrTab(const Elf_Shdr *sh) const; protected: @@ -404,7 +513,8 @@ protected: public: const Elf_Dyn *getDyn(DataRefImpl DynData) const; - + error_code getSymbolVersion(SymbolRef Symb, StringRef &Version, + bool &IsDefault) const; protected: virtual error_code getSymbolNext(DataRefImpl Symb, SymbolRef &Res) const; virtual error_code getSymbolName(DataRefImpl Symb, StringRef &Res) const; @@ -473,6 +583,7 @@ public: virtual uint8_t getBytesInAddress() const; virtual StringRef getFileFormatName() const; + virtual StringRef getObjectType() const { return "ELF"; } virtual unsigned getArch() const; virtual StringRef getLoadName() const; @@ -490,6 +601,89 @@ public: static inline bool classof(const ELFObjectFile *v) { return true; } }; +// Iterate through the version definitions, and place each Elf_Verdef +// in the VersionMap according to its index. +template<support::endianness target_endianness, bool is64Bits> +void ELFObjectFile<target_endianness, is64Bits>:: + LoadVersionDefs(const Elf_Shdr *sec) const { + unsigned vd_size = sec->sh_size; // Size of section in bytes + unsigned vd_count = sec->sh_info; // Number of Verdef entries + const char *sec_start = (const char*)base() + sec->sh_offset; + const char *sec_end = sec_start + vd_size; + // The first Verdef entry is at the start of the section. + const char *p = sec_start; + for (unsigned i = 0; i < vd_count; i++) { + if (p + sizeof(Elf_Verdef) > sec_end) + report_fatal_error("Section ended unexpectedly while scanning " + "version definitions."); + const Elf_Verdef *vd = reinterpret_cast<const Elf_Verdef *>(p); + if (vd->vd_version != ELF::VER_DEF_CURRENT) + report_fatal_error("Unexpected verdef version"); + size_t index = vd->vd_ndx & ELF::VERSYM_VERSION; + if (index >= VersionMap.size()) + VersionMap.resize(index+1); + VersionMap[index] = VersionMapEntry(vd); + p += vd->vd_next; + } +} + +// Iterate through the versions needed section, and place each Elf_Vernaux +// in the VersionMap according to its index. +template<support::endianness target_endianness, bool is64Bits> +void ELFObjectFile<target_endianness, is64Bits>:: + LoadVersionNeeds(const Elf_Shdr *sec) const { + unsigned vn_size = sec->sh_size; // Size of section in bytes + unsigned vn_count = sec->sh_info; // Number of Verneed entries + const char *sec_start = (const char*)base() + sec->sh_offset; + const char *sec_end = sec_start + vn_size; + // The first Verneed entry is at the start of the section. + const char *p = sec_start; + for (unsigned i = 0; i < vn_count; i++) { + if (p + sizeof(Elf_Verneed) > sec_end) + report_fatal_error("Section ended unexpectedly while scanning " + "version needed records."); + const Elf_Verneed *vn = reinterpret_cast<const Elf_Verneed *>(p); + if (vn->vn_version != ELF::VER_NEED_CURRENT) + report_fatal_error("Unexpected verneed version"); + // Iterate through the Vernaux entries + const char *paux = p + vn->vn_aux; + for (unsigned j = 0; j < vn->vn_cnt; j++) { + if (paux + sizeof(Elf_Vernaux) > sec_end) + report_fatal_error("Section ended unexpected while scanning auxiliary " + "version needed records."); + const Elf_Vernaux *vna = reinterpret_cast<const Elf_Vernaux *>(paux); + size_t index = vna->vna_other & ELF::VERSYM_VERSION; + if (index >= VersionMap.size()) + VersionMap.resize(index+1); + VersionMap[index] = VersionMapEntry(vna); + paux += vna->vna_next; + } + p += vn->vn_next; + } +} + +template<support::endianness target_endianness, bool is64Bits> +void ELFObjectFile<target_endianness, is64Bits>::LoadVersionMap() const { + // If there is no dynamic symtab or version table, there is nothing to do. + if (SymbolTableSections[0] == NULL || dot_gnu_version_sec == NULL) + return; + + // Has the VersionMap already been loaded? + if (VersionMap.size() > 0) + return; + + // The first two version indexes are reserved. + // Index 0 is LOCAL, index 1 is GLOBAL. + VersionMap.push_back(VersionMapEntry()); + VersionMap.push_back(VersionMapEntry()); + + if (dot_gnu_version_d_sec) + LoadVersionDefs(dot_gnu_version_d_sec); + + if (dot_gnu_version_r_sec) + LoadVersionNeeds(dot_gnu_version_r_sec); +} + template<support::endianness target_endianness, bool is64Bits> void ELFObjectFile<target_endianness, is64Bits> ::validateSymbol(DataRefImpl Symb) const { @@ -547,6 +741,18 @@ error_code ELFObjectFile<target_endianness, is64Bits> } template<support::endianness target_endianness, bool is64Bits> +error_code ELFObjectFile<target_endianness, is64Bits> + ::getSymbolVersion(SymbolRef SymRef, + StringRef &Version, + bool &IsDefault) const { + DataRefImpl Symb = SymRef.getRawDataRefImpl(); + validateSymbol(Symb); + const Elf_Sym *symb = getSymbol(Symb); + return getSymbolVersion(SymbolTableSections[Symb.d.b], symb, + Version, IsDefault); +} + +template<support::endianness target_endianness, bool is64Bits> ELF::Elf64_Word ELFObjectFile<target_endianness, is64Bits> ::getSymbolTableIndex(const Elf_Sym *symb) const { if (symb->st_shndx == ELF::SHN_XINDEX) @@ -1266,7 +1472,11 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object , dot_strtab_sec(0) , dot_dynstr_sec(0) , dot_dynamic_sec(0) - , dt_soname(0) { + , dot_gnu_version_sec(0) + , dot_gnu_version_r_sec(0) + , dot_gnu_version_d_sec(0) + , dt_soname(0) + { const uint64_t FileSize = Data->getBufferSize(); @@ -1302,31 +1512,60 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object SymbolTableSections.push_back(NULL); for (uint64_t i = 0, e = getNumSections(); i != e; ++i) { - if (sh->sh_type == ELF::SHT_SYMTAB_SHNDX) { + switch (sh->sh_type) { + case ELF::SHT_SYMTAB_SHNDX: { if (SymbolTableSectionHeaderIndex) // FIXME: Proper error handling. report_fatal_error("More than one .symtab_shndx!"); SymbolTableSectionHeaderIndex = sh; + break; } - if (sh->sh_type == ELF::SHT_SYMTAB) { + case ELF::SHT_SYMTAB: { SymbolTableSectionsIndexMap[i] = SymbolTableSections.size(); SymbolTableSections.push_back(sh); + break; } - if (sh->sh_type == ELF::SHT_DYNSYM) { + case ELF::SHT_DYNSYM: { if (SymbolTableSections[0] != NULL) // FIXME: Proper error handling. report_fatal_error("More than one .dynsym!"); SymbolTableSectionsIndexMap[i] = 0; SymbolTableSections[0] = sh; + break; } - if (sh->sh_type == ELF::SHT_REL || sh->sh_type == ELF::SHT_RELA) { + case ELF::SHT_REL: + case ELF::SHT_RELA: { SectionRelocMap[getSection(sh->sh_info)].push_back(i); + break; } - if (sh->sh_type == ELF::SHT_DYNAMIC) { + case ELF::SHT_DYNAMIC: { if (dot_dynamic_sec != NULL) // FIXME: Proper error handling. report_fatal_error("More than one .dynamic!"); dot_dynamic_sec = sh; + break; + } + case ELF::SHT_GNU_versym: { + if (dot_gnu_version_sec != NULL) + // FIXME: Proper error handling. + report_fatal_error("More than one .gnu.version section!"); + dot_gnu_version_sec = sh; + break; + } + case ELF::SHT_GNU_verdef: { + if (dot_gnu_version_d_sec != NULL) + // FIXME: Proper error handling. + report_fatal_error("More than one .gnu.version_d section!"); + dot_gnu_version_d_sec = sh; + break; + } + case ELF::SHT_GNU_verneed: { + if (dot_gnu_version_r_sec != NULL) + // FIXME: Proper error handling. + report_fatal_error("More than one .gnu.version_r section!"); + dot_gnu_version_r_sec = sh; + break; + } } ++sh; } @@ -1776,6 +2015,89 @@ error_code ELFObjectFile<target_endianness, is64Bits> } template<support::endianness target_endianness, bool is64Bits> +error_code ELFObjectFile<target_endianness, is64Bits> + ::getSymbolVersion(const Elf_Shdr *section, + const Elf_Sym *symb, + StringRef &Version, + bool &IsDefault) const { + // Handle non-dynamic symbols. + if (section != SymbolTableSections[0]) { + // Non-dynamic symbols can have versions in their names + // A name of the form 'foo@V1' indicates version 'V1', non-default. + // A name of the form 'foo@@V2' indicates version 'V2', default version. + StringRef Name; + error_code ec = getSymbolName(section, symb, Name); + if (ec != object_error::success) + return ec; + size_t atpos = Name.find('@'); + if (atpos == StringRef::npos) { + Version = ""; + IsDefault = false; + return object_error::success; + } + ++atpos; + if (atpos < Name.size() && Name[atpos] == '@') { + IsDefault = true; + ++atpos; + } else { + IsDefault = false; + } + Version = Name.substr(atpos); + return object_error::success; + } + + // This is a dynamic symbol. Look in the GNU symbol version table. + if (dot_gnu_version_sec == NULL) { + // No version table. + Version = ""; + IsDefault = false; + return object_error::success; + } + + // Determine the position in the symbol table of this entry. + const char *sec_start = (const char*)base() + section->sh_offset; + size_t entry_index = ((const char*)symb - sec_start)/section->sh_entsize; + + // Get the corresponding version index entry + const Elf_Versym *vs = getEntry<Elf_Versym>(dot_gnu_version_sec, entry_index); + size_t version_index = vs->vs_index & ELF::VERSYM_VERSION; + + // Special markers for unversioned symbols. + if (version_index == ELF::VER_NDX_LOCAL || + version_index == ELF::VER_NDX_GLOBAL) { + Version = ""; + IsDefault = false; + return object_error::success; + } + + // Lookup this symbol in the version table + LoadVersionMap(); + if (version_index >= VersionMap.size() || VersionMap[version_index].isNull()) + report_fatal_error("Symbol has version index without corresponding " + "define or reference entry"); + const VersionMapEntry &entry = VersionMap[version_index]; + + // Get the version name string + size_t name_offset; + if (entry.isVerdef()) { + // The first Verdaux entry holds the name. + name_offset = entry.getVerdef()->getAux()->vda_name; + } else { + name_offset = entry.getVernaux()->vna_name; + } + Version = getString(dot_dynstr_sec, name_offset); + + // Set IsDefault + if (entry.isVerdef()) { + IsDefault = !(vs->vs_index & ELF::VERSYM_HIDDEN); + } else { + IsDefault = false; + } + + return object_error::success; +} + +template<support::endianness target_endianness, bool is64Bits> inline DynRefImpl<target_endianness, is64Bits> ::DynRefImpl(DataRefImpl DynP, const OwningType *Owner) : DynPimpl(DynP) @@ -1823,6 +2145,35 @@ inline DataRefImpl DynRefImpl<target_endianness, is64Bits> return DynPimpl; } +/// This is a generic interface for retrieving GNU symbol version +/// information from an ELFObjectFile. +static inline error_code GetELFSymbolVersion(const ObjectFile *Obj, + const SymbolRef &Sym, + StringRef &Version, + bool &IsDefault) { + // Little-endian 32-bit + if (const ELFObjectFile<support::little, false> *ELFObj = + dyn_cast<ELFObjectFile<support::little, false> >(Obj)) + return ELFObj->getSymbolVersion(Sym, Version, IsDefault); + + // Big-endian 32-bit + if (const ELFObjectFile<support::big, false> *ELFObj = + dyn_cast<ELFObjectFile<support::big, false> >(Obj)) + return ELFObj->getSymbolVersion(Sym, Version, IsDefault); + + // Little-endian 64-bit + if (const ELFObjectFile<support::little, true> *ELFObj = + dyn_cast<ELFObjectFile<support::little, true> >(Obj)) + return ELFObj->getSymbolVersion(Sym, Version, IsDefault); + + // Big-endian 64-bit + if (const ELFObjectFile<support::big, true> *ELFObj = + dyn_cast<ELFObjectFile<support::big, true> >(Obj)) + return ELFObj->getSymbolVersion(Sym, Version, IsDefault); + + llvm_unreachable("Object passed to GetELFSymbolVersion() is not ELF"); +} + } } |