[lld][GNU Properties] Refactor storage of PAuth ABI core info

Previously, the AArch64 PAuth ABI core values were stored as an ArrayRef<uint8_t>,
introducing unnecessary indirection.

This patch replaces the ArrayRef with two explicit uint64_t fields:
aarch64PauthAbiPlatform and aarch64PauthAbiVersion. This simplifies the
representation and improves readability.

No functional change intended.

Author: sivan-shani

lld/ELF/Arch/AArch64.cpp

@@ -1044,8 +1044,9 @@ AArch64BtiPac::AArch64BtiPac(Ctx &ctx) : AArch64(ctx) {
   // instructions.
 
   if (ctx.arg.zPacPlt) {
-    if (llvm::any_of(ctx.aarch64PauthAbiCoreInfo,
-                     [](uint8_t c) { return c != 0; }))
+    if (ctx.aarch64PauthAbiCoreInfo.has_value() &&
+        (ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform != 0 ||
+         ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion != 0))
       pacEntryKind = PEK_Auth;
     else
       pacEntryKind = PEK_AuthHint;

lld/ELF/Config.h

@@ -29,6 +29,7 @@
 #include "llvm/Support/GlobPattern.h"
 #include "llvm/Support/TarWriter.h"
 #include <atomic>
+#include <cstdint>
 #include <memory>
 #include <mutex>
 #include <optional>
@@ -139,6 +140,11 @@ enum class GcsPolicy { Implicit, Never, Always };
 // For some options that resemble -z bti-report={none,warning,error}
 enum class ReportPolicy { None, Warning, Error };
 
+struct AArch64PauthAbiCoreInfo {
+  uint64_t aarch64PauthAbiPlatform;
+  uint64_t aarch64PauthAbiVersion;
+};
+
 struct SymbolVersion {
   llvm::StringRef name;
   bool isExternCpp;
@@ -695,7 +701,7 @@ struct Ctx : CommonLinkerContext {
 
   llvm::raw_fd_ostream openAuxiliaryFile(llvm::StringRef, std::error_code &);
 
-  ArrayRef<uint8_t> aarch64PauthAbiCoreInfo;
+  std::optional<AArch64PauthAbiCoreInfo> aarch64PauthAbiCoreInfo;
 };
 
 // The first two elements of versionDefinitions represent VER_NDX_LOCAL and

lld/ELF/Driver.cpp

@@ -2841,15 +2841,17 @@ static void readSecurityNotes(Ctx &ctx) {
   StringRef referenceFileName;
   if (ctx.arg.emachine == EM_AARCH64) {
     auto it = llvm::find_if(ctx.objectFiles, [](const ELFFileBase *f) {
-      return !f->aarch64PauthAbiCoreInfo.empty();
+      return f->aarch64PauthAbiCoreInfo.has_value();
     });
     if (it != ctx.objectFiles.end()) {
       ctx.aarch64PauthAbiCoreInfo = (*it)->aarch64PauthAbiCoreInfo;
       referenceFileName = (*it)->getName();
     }
   }
-  bool hasValidPauthAbiCoreInfo = llvm::any_of(
-      ctx.aarch64PauthAbiCoreInfo, [](uint8_t c) { return c != 0; });
+  bool hasValidPauthAbiCoreInfo =
+      ctx.aarch64PauthAbiCoreInfo.has_value() &&
+      (ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform != 0 ||
+       ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion != 0);
 
   auto report = [&](ReportPolicy policy) -> ELFSyncStream {
     return {ctx, toDiagLevel(policy)};
@@ -2909,10 +2911,10 @@ static void readSecurityNotes(Ctx &ctx) {
     }
     ctx.arg.andFeatures &= features;
 
-    if (ctx.aarch64PauthAbiCoreInfo.empty())
+    if (!ctx.aarch64PauthAbiCoreInfo)
       continue;
 
-    if (f->aarch64PauthAbiCoreInfo.empty()) {
+    if (!f->aarch64PauthAbiCoreInfo) {
       report(ctx.arg.zPauthReport)
           << f
           << ": -z pauth-report: file does not have AArch64 "
@@ -2921,12 +2923,25 @@ static void readSecurityNotes(Ctx &ctx) {
       continue;
     }
 
-    if (ctx.aarch64PauthAbiCoreInfo != f->aarch64PauthAbiCoreInfo)
-      Err(ctx) << "incompatible values of AArch64 PAuth core info found\n>>> "
+    if (ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform !=
+        f->aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform)
+      Err(ctx) << "incompatible AArch64 PAuth Platform Values\n>>> "
                << referenceFileName << ": 0x"
-               << toHex(ctx.aarch64PauthAbiCoreInfo, /*LowerCase=*/true)
+               << toHex(ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform,
+                        /*LowerCase=*/true)
                << "\n>>> " << f << ": 0x"
-               << toHex(f->aarch64PauthAbiCoreInfo, /*LowerCase=*/true);
+               << toHex(f->aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform,
+                        /*LowerCase=*/true);
+
+    if (ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion !=
+        f->aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion)
+      Err(ctx) << "incompatible AArch64 PAuth Version Values\n>>> "
+               << referenceFileName << ": 0x"
+               << toHex(ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion,
+                        /*LowerCase=*/true)
+               << "\n>>> " << f << ": 0x"
+               << toHex(f->aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion,
+                        /*LowerCase=*/true);
   }
 
   // Force enable Shadow Stack.

lld/ELF/InputFiles.cpp

@@ -950,7 +950,7 @@ static void parseGnuPropertyNote(Ctx &ctx, ELFFileBase &f,
     } else if (ctx.arg.emachine == EM_AARCH64 &&
                type == GNU_PROPERTY_AARCH64_FEATURE_PAUTH) {
       ArrayRef<uint8_t> contents = data ? *data : desc;
-      if (!f.aarch64PauthAbiCoreInfo.empty()) {
+      if (f.aarch64PauthAbiCoreInfo) {
         return void(
             err(contents.data())
             << "multiple GNU_PROPERTY_AARCH64_FEATURE_PAUTH entries are "
@@ -961,7 +961,11 @@ static void parseGnuPropertyNote(Ctx &ctx, ELFFileBase &f,
                        "is invalid: expected 16 bytes, but got "
                     << size);
       }
-      f.aarch64PauthAbiCoreInfo = desc;
+      f.aarch64PauthAbiCoreInfo.emplace();
+      f.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform =
+          support::endian::read64<ELFT::Endianness>(&desc[0]);
+      f.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion =
+          support::endian::read64<ELFT::Endianness>(&desc[8]);
     }
 
     // Padding is present in the note descriptor, if necessary.

lld/ELF/InputFiles.h

@@ -241,7 +241,7 @@ class ELFFileBase : public InputFile {
   StringRef sourceFile;
   uint32_t andFeatures = 0;
   bool hasCommonSyms = false;
-  ArrayRef<uint8_t> aarch64PauthAbiCoreInfo;
+  std::optional<AArch64PauthAbiCoreInfo> aarch64PauthAbiCoreInfo;
 };
 
 // .o file.

lld/ELF/SyntheticSections.cpp

@@ -344,20 +344,22 @@ void GnuPropertySection::writeTo(uint8_t *buf) {
     offset += 16;
   }
 
-  if (!ctx.aarch64PauthAbiCoreInfo.empty()) {
+  if (ctx.aarch64PauthAbiCoreInfo) {
     write32(ctx, buf + offset + 0, GNU_PROPERTY_AARCH64_FEATURE_PAUTH);
-    write32(ctx, buf + offset + 4, ctx.aarch64PauthAbiCoreInfo.size());
-    memcpy(buf + offset + 8, ctx.aarch64PauthAbiCoreInfo.data(),
-           ctx.aarch64PauthAbiCoreInfo.size());
+    write32(ctx, buf + offset + 4, sizeof(uint64_t) * 2);
+    write64(ctx, buf + offset + 8,
+            ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiPlatform);
+    write64(ctx, buf + offset + 16,
+            ctx.aarch64PauthAbiCoreInfo->aarch64PauthAbiVersion);
   }
 }
 
 size_t GnuPropertySection::getSize() const {
   uint32_t contentSize = 0;
   if (ctx.arg.andFeatures != 0)
     contentSize += ctx.arg.is64 ? 16 : 12;
-  if (!ctx.aarch64PauthAbiCoreInfo.empty())
-    contentSize += 4 + 4 + ctx.aarch64PauthAbiCoreInfo.size();
+  if (ctx.aarch64PauthAbiCoreInfo)
+    contentSize += 4 + 4 + sizeof(uint64_t) * 2;
   assert(contentSize != 0);
   return contentSize + 16;
 }
@@ -4959,7 +4961,7 @@ template <class ELFT> void elf::createSyntheticSections(Ctx &ctx) {
   ctx.in.iplt = std::make_unique<IpltSection>(ctx);
   add(*ctx.in.iplt);
 
-  if (ctx.arg.andFeatures || !ctx.aarch64PauthAbiCoreInfo.empty()) {
+  if (ctx.arg.andFeatures || ctx.aarch64PauthAbiCoreInfo) {
     ctx.in.gnuProperty = std::make_unique<GnuPropertySection>(ctx);
     add(*ctx.in.gnuProperty);
   }

lld/test/ELF/aarch64-feature-pauth.s

@@ -12,9 +12,9 @@
 # RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu abi-tag2.s -o tag2.o
 # RUN: not ld.lld tag1.o tag1a.o tag2.o -o /dev/null 2>&1 | FileCheck --check-prefix ERR1 %s
 
-# ERR1:      error: incompatible values of AArch64 PAuth core info found
-# ERR1-NEXT: >>> tag1.o: 0x2a000000000000000{{1|2}}00000000000000
-# ERR1-NEXT: >>> tag2.o: 0x2a000000000000000{{1|2}}00000000000000
+# ERR1:      error: incompatible AArch64 PAuth Version Values
+# ERR1-NEXT: >>> tag1.o: 0x01
+# ERR1-NEXT: >>> tag2.o: 0x02
 
 # RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu abi-tag-short.s -o short.o
 # RUN: not ld.lld short.o -o /dev/null 2>&1 | FileCheck --check-prefix ERR2 %s