[lld] [lld][AArch64][ELF][PAC] Support AUTH relocations and AUTH ELF marking (PR #72714)

[Fangrui Song via llvm-commits]

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@@ -962,6 +962,44 @@ template <class ELFT> static uint32_t readAndFeatures(const InputSection &sec) {
   return featuresSet;
 }
 
+// Extract compatibility info for aarch64 pointer authentication from the
+// .note.AARCH64-PAUTH-ABI-tag section and write it to the corresponding ObjFile
+// field. See the following ABI documentation:
+// https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#elf-marking
+template <class ELFT>
+static void readAArch64PauthAbiTag(const InputSection &sec, ObjFile<ELFT> &f) {
+  using Elf_Nhdr = typename ELFT::Nhdr;
+  using Elf_Note = typename ELFT::Note;
+  ArrayRef<uint8_t> data = sec.content();
+  auto reportError = [&](const Twine &msg) {
+    errorOrWarn(toString(sec.file) + ":(" + sec.name + "): " + msg);
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MaskRay wrote:

Unneeded helper. Just use `lld::toString(const InputSectionBase *sec)`

https://github.com/llvm/llvm-project/pull/72714