[yaml2obj, obj2yaml] - Add support for SHT_NOTE sections.
SHT_NOTE is the section that consists of
namesz, descsz, type, name + padding, desc + padding data.
This patch teaches yaml2obj, obj2yaml to dump and parse them.
This patch implements the section how it is described here:
https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-18048.html
Which says: "For 64–bit objects and 32–bit objects, each entry is an array of 4-byte words in
the format of the target processor"
The official specification is different
http://www.sco.com/developers/gabi/latest/ch5.pheader.html#note_section
And says: "n 64-bit objects (files with e_ident[EI_CLASS] equal to ELFCLASS64), each entry is an array
of 8-byte words in the format of the target processor. In 32-bit objects (files with e_ident[EI_CLASS]
equal to ELFCLASS32), each entry is an array of 4-byte words in the format of the target processor"
Since LLVM uses the first, 32-bit way, this patch follows it.
Differential revision: https://reviews.llvm.org/D68983
diff --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index 8ba1608..dae3f39 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -36,6 +36,16 @@
SmallVector<char, 128> Buf;
raw_svector_ostream OS;
+public:
+ ContiguousBlobAccumulator(uint64_t InitialOffset_)
+ : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
+
+ template <class Integer>
+ raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
+ Offset = padToAlignment(Align);
+ return OS;
+ }
+
/// \returns The new offset.
uint64_t padToAlignment(unsigned Align) {
if (Align == 0)
@@ -46,14 +56,6 @@
return AlignedOffset; // == CurrentOffset;
}
-public:
- ContiguousBlobAccumulator(uint64_t InitialOffset_)
- : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
- template <class Integer>
- raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
- Offset = padToAlignment(Align);
- return OS;
- }
void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
};
@@ -177,6 +179,9 @@
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::AddrsigSection &Section,
ContiguousBlobAccumulator &CBA);
+ void writeSectionContent(Elf_Shdr &SHeader,
+ const ELFYAML::NoteSection &Section,
+ ContiguousBlobAccumulator &CBA);
ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
@@ -440,6 +445,8 @@
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
+ } else if (auto S = dyn_cast<ELFYAML::NoteSection>(Sec)) {
+ writeSectionContent(SHeader, *S, CBA);
} else {
llvm_unreachable("Unknown section type");
}
@@ -1035,6 +1042,55 @@
}
}
+template <class ELFT>
+void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
+ const ELFYAML::NoteSection &Section,
+ ContiguousBlobAccumulator &CBA) {
+ raw_ostream &OS =
+ CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+ uint64_t Offset = OS.tell();
+
+ if (Section.Content || Section.Size) {
+ SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+ return;
+ }
+
+ for (const ELFYAML::NoteEntry &NE : *Section.Notes) {
+ // Write name size.
+ if (NE.Name.empty())
+ support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
+ else
+ support::endian::write<uint32_t>(OS, NE.Name.size() + 1,
+ ELFT::TargetEndianness);
+
+ // Write description size.
+ if (NE.Desc.binary_size() == 0)
+ support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
+ else
+ support::endian::write<uint32_t>(OS, NE.Desc.binary_size(),
+ ELFT::TargetEndianness);
+
+ // Write type.
+ support::endian::write<uint32_t>(OS, NE.Type, ELFT::TargetEndianness);
+
+ // Write name, null terminator and padding.
+ if (!NE.Name.empty()) {
+ support::endian::write<uint8_t>(OS, arrayRefFromStringRef(NE.Name),
+ ELFT::TargetEndianness);
+ support::endian::write<uint8_t>(OS, 0, ELFT::TargetEndianness);
+ CBA.padToAlignment(4);
+ }
+
+ // Write description and padding.
+ if (NE.Desc.binary_size() != 0) {
+ NE.Desc.writeAsBinary(OS);
+ CBA.padToAlignment(4);
+ }
+ }
+
+ SHeader.sh_size = OS.tell() - Offset;
+}
+
template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
StringRef Name = Doc.Sections[I]->Name;