1 files changed, 25 insertions, 0 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
index e96c5a953ff2..a0f0a489816c 100644
--- a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
@@ -16,6 +16,7 @@
 #include "AArch64MachineFunctionInfo.h"
 #include "AArch64InstrInfo.h"
 #include "AArch64Subtarget.h"
+#include "llvm/BinaryFormat/ELF.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
@@ -72,6 +73,29 @@ static bool ShouldSignWithBKey(const Function &F, const AArch64Subtarget &STI) {
   return Key == "b_key";
 }
 
+// Determine if we need to treat pointers in GOT as signed (as described in
+// https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#appendix-signed-got)
+// based on PAuth core info encoded as "aarch64-elf-pauthabi-platform" and
+// "aarch64-elf-pauthabi-version" module flags. Currently, only
+// AARCH64_PAUTH_PLATFORM_LLVM_LINUX platform supports signed GOT with
+// AARCH64_PAUTH_PLATFORM_LLVM_LINUX_VERSION_GOT bit in version value set.
+static bool hasELFSignedGOTHelper(const Function &F,
+                                  const AArch64Subtarget *STI) {
+  if (!Triple(STI->getTargetTriple()).isOSBinFormatELF())
+    return false;
+  const Module *M = F.getParent();
+  const auto *PAP = mdconst::extract_or_null<ConstantInt>(
+      M->getModuleFlag("aarch64-elf-pauthabi-platform"));
+  if (!PAP || PAP->getZExtValue() != ELF::AARCH64_PAUTH_PLATFORM_LLVM_LINUX)
+    return false;
+  const auto *PAV = mdconst::extract_or_null<ConstantInt>(
+      M->getModuleFlag("aarch64-elf-pauthabi-version"));
+  if (!PAV)
+    return false;
+  return PAV->getZExtValue() &
+         (1 << ELF::AARCH64_PAUTH_PLATFORM_LLVM_LINUX_VERSION_GOT);
+}
+
 AArch64FunctionInfo::AArch64FunctionInfo(const Function &F,
                                          const AArch64Subtarget *STI) {
   // If we already know that the function doesn't have a redzone, set
@@ -80,6 +104,7 @@ AArch64FunctionInfo::AArch64FunctionInfo(const Function &F,
     HasRedZone = false;
   std::tie(SignReturnAddress, SignReturnAddressAll) = GetSignReturnAddress(F);
   SignWithBKey = ShouldSignWithBKey(F, *STI);
+  HasELFSignedGOT = hasELFSignedGOTHelper(F, STI);
   // TODO: skip functions that have no instrumented allocas for optimization
   IsMTETagged = F.hasFnAttribute(Attribute::SanitizeMemTag);