[yaml2obj/obj2yaml] - Add support for SHT_GNU_HASH section.
This adds parsing and dumping support for GNU hash sections.
They are described nicely here: https://blogs.oracle.com/solaris/gnu-hash-elf-sections-v2
Differential revision: https://reviews.llvm.org/D69399
diff --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index 64b5cd4..be733dc 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -182,6 +182,9 @@
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoteSection &Section,
ContiguousBlobAccumulator &CBA);
+ void writeSectionContent(Elf_Shdr &SHeader,
+ const ELFYAML::GnuHashSection &Section,
+ ContiguousBlobAccumulator &CBA);
ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
@@ -440,6 +443,8 @@
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::NoteSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
+ } else if (auto S = dyn_cast<ELFYAML::GnuHashSection>(Sec)) {
+ writeSectionContent(SHeader, *S, CBA);
} else {
llvm_unreachable("Unknown section type");
}
@@ -1091,6 +1096,70 @@
SHeader.sh_size = OS.tell() - Offset;
}
+template <class ELFT>
+void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
+ const ELFYAML::GnuHashSection &Section,
+ ContiguousBlobAccumulator &CBA) {
+ raw_ostream &OS =
+ CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+
+ unsigned Link = 0;
+ if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
+ SHeader.sh_link = Link;
+
+ if (Section.Content) {
+ SHeader.sh_size = writeContent(OS, Section.Content, None);
+ return;
+ }
+
+ // We write the header first, starting with the hash buckets count. Normally
+ // it is the number of entries in HashBuckets, but the "NBuckets" property can
+ // be used to override this field, which is useful for producing broken
+ // objects.
+ if (Section.Header->NBuckets)
+ support::endian::write<uint32_t>(OS, *Section.Header->NBuckets,
+ ELFT::TargetEndianness);
+ else
+ support::endian::write<uint32_t>(OS, Section.HashBuckets->size(),
+ ELFT::TargetEndianness);
+
+ // Write the index of the first symbol in the dynamic symbol table accessible
+ // via the hash table.
+ support::endian::write<uint32_t>(OS, Section.Header->SymNdx,
+ ELFT::TargetEndianness);
+
+ // Write the number of words in the Bloom filter. As above, the "MaskWords"
+ // property can be used to set this field to any value.
+ if (Section.Header->MaskWords)
+ support::endian::write<uint32_t>(OS, *Section.Header->MaskWords,
+ ELFT::TargetEndianness);
+ else
+ support::endian::write<uint32_t>(OS, Section.BloomFilter->size(),
+ ELFT::TargetEndianness);
+
+ // Write the shift constant used by the Bloom filter.
+ support::endian::write<uint32_t>(OS, Section.Header->Shift2,
+ ELFT::TargetEndianness);
+
+ // We've finished writing the header. Now write the Bloom filter.
+ for (llvm::yaml::Hex64 Val : *Section.BloomFilter)
+ support::endian::write<typename ELFT::uint>(OS, Val,
+ ELFT::TargetEndianness);
+
+ // Write an array of hash buckets.
+ for (llvm::yaml::Hex32 Val : *Section.HashBuckets)
+ support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+
+ // Write an array of hash values.
+ for (llvm::yaml::Hex32 Val : *Section.HashValues)
+ support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+
+ SHeader.sh_size = 16 /*Header size*/ +
+ Section.BloomFilter->size() * sizeof(typename ELFT::uint) +
+ Section.HashBuckets->size() * 4 +
+ Section.HashValues->size() * 4;
+}
+
template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
StringRef Name = Doc.Sections[I]->Name;
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index f362b9c..5872cbb 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -1039,6 +1039,15 @@
IO.mapOptional("Notes", Section.Notes);
}
+
+static void sectionMapping(IO &IO, ELFYAML::GnuHashSection &Section) {
+ commonSectionMapping(IO, Section);
+ IO.mapOptional("Content", Section.Content);
+ IO.mapOptional("Header", Section.Header);
+ IO.mapOptional("BloomFilter", Section.BloomFilter);
+ IO.mapOptional("HashBuckets", Section.HashBuckets);
+ IO.mapOptional("HashValues", Section.HashValues);
+}
static void sectionMapping(IO &IO, ELFYAML::NoBitsSection &Section) {
commonSectionMapping(IO, Section);
IO.mapOptional("Size", Section.Size, Hex64(0));
@@ -1155,6 +1164,11 @@
Section.reset(new ELFYAML::NoteSection());
sectionMapping(IO, *cast<ELFYAML::NoteSection>(Section.get()));
break;
+ case ELF::SHT_GNU_HASH:
+ if (!IO.outputting())
+ Section.reset(new ELFYAML::GnuHashSection());
+ sectionMapping(IO, *cast<ELFYAML::GnuHashSection>(Section.get()));
+ break;
case ELF::SHT_MIPS_ABIFLAGS:
if (!IO.outputting())
Section.reset(new ELFYAML::MipsABIFlags());
@@ -1300,6 +1314,29 @@
return {};
}
+ if (const auto *Sec = dyn_cast<ELFYAML::GnuHashSection>(Section.get())) {
+ if (!Sec->Content && !Sec->Header && !Sec->BloomFilter &&
+ !Sec->HashBuckets && !Sec->HashValues)
+ return "either \"Content\" or \"Header\", \"BloomFilter\", "
+ "\"HashBuckets\" and \"HashBuckets\" must be specified";
+
+ if (Sec->Header || Sec->BloomFilter || Sec->HashBuckets ||
+ Sec->HashValues) {
+ if (!Sec->Header || !Sec->BloomFilter || !Sec->HashBuckets ||
+ !Sec->HashValues)
+ return "\"Header\", \"BloomFilter\", "
+ "\"HashBuckets\" and \"HashValues\" must be used together";
+ if (Sec->Content)
+ return "\"Header\", \"BloomFilter\", "
+ "\"HashBuckets\" and \"HashValues\" can't be used together with "
+ "\"Content\"";
+ return {};
+ }
+
+ // Only Content is specified.
+ return {};
+ }
+
return {};
}
@@ -1335,6 +1372,15 @@
IO.mapRequired("Size", E.Size);
}
+void MappingTraits<ELFYAML::GnuHashHeader>::mapping(IO &IO,
+ ELFYAML::GnuHashHeader &E) {
+ assert(IO.getContext() && "The IO context is not initialized");
+ IO.mapOptional("NBuckets", E.NBuckets);
+ IO.mapRequired("SymNdx", E.SymNdx);
+ IO.mapOptional("MaskWords", E.MaskWords);
+ IO.mapRequired("Shift2", E.Shift2);
+}
+
void MappingTraits<ELFYAML::DynamicEntry>::mapping(IO &IO,
ELFYAML::DynamicEntry &Rel) {
assert(IO.getContext() && "The IO context is not initialized");