[Clang][AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (2/3) #125688

Il-Capitano · 2025-02-04T14:13:43Z

Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304

The general implementation follows the existing one for ARM targets. Simlarly to ARM targets, generating object files with the SHF_AARCH64_PURECODE flag set is enabled by the -mexecute-only/-mpure-code driver flag.

Related PRs:

LLVM: [AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (1/3) #125687
LLD: [LLD][ELF][AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (3/3) #125689

llvmbot · 2025-02-04T14:14:19Z

@llvm/pr-subscribers-mc
@llvm/pr-subscribers-backend-aarch64
@llvm/pr-subscribers-clang
@llvm/pr-subscribers-clang-driver
@llvm/pr-subscribers-objectyaml

@llvm/pr-subscribers-llvm-transforms

Author: Csanád Hajdú (Il-Capitano)

Changes

Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304

The general implementation follows the existing one for ARM targets. Simlarly to ARM targets, generating object files with the SHF_AARCH64_PURECODE flag set is enabled by the -mexecute-only/-mpure-code driver flag.

Depends on #125687. The changes in that PR are included here as well for now, but will be removed once that gets merged.

Patch is 26.08 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/125688.diff

23 Files Affected:

(modified) clang/include/clang/Driver/Options.td (+2-2)
(modified) clang/lib/Driver/ToolChains/Arch/AArch64.cpp (+11)
(added) clang/test/CodeGen/aarch64-execute-only.c (+24)
(added) clang/test/Driver/aarch64-execute-only.c (+6)
(modified) clang/test/Driver/fsanitize.c (+7-1)
(modified) llvm/include/llvm/BinaryFormat/ELF.h (+4-1)
(modified) llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp (+8-5)
(modified) llvm/lib/MC/MCParser/ELFAsmParser.cpp (+5-2)
(modified) llvm/lib/MC/MCSectionELF.cpp (+3)
(modified) llvm/lib/ObjectYAML/ELFYAML.cpp (+3)
(modified) llvm/lib/Target/AArch64/AArch64Features.td (+5)
(modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp (+26)
(modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.h (+6)
(modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp (+16-1)
(modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h (+2)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp (+18)
(added) llvm/test/CodeGen/AArch64/execute-only-section.ll (+21)
(added) llvm/test/MC/ELF/AArch64/execute-only-populated-text-section.s (+27)
(added) llvm/test/MC/ELF/AArch64/execute-only-section.s (+43)
(added) llvm/test/MC/ELF/AArch64/execute-only-text-section-data.s (+27)
(modified) llvm/test/MC/ELF/section-flags-unknown.s (+3)
(modified) llvm/test/Transforms/Inline/AArch64/inline-target-attr.ll (+25)
(modified) llvm/tools/llvm-readobj/ELFDumper.cpp (+8)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 0ab923fcdd5838c..028d74c9711d1f0 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4677,9 +4677,9 @@ def mno_long_calls : Flag<["-"], "mno-long-calls">, Group<m_Group>,
   HelpText<"Restore the default behaviour of not generating long calls">;
 } // let Flags = [TargetSpecific]
 def mexecute_only : Flag<["-"], "mexecute-only">, Group<m_arm_Features_Group>,
-  HelpText<"Disallow generation of data access to code sections (ARM only)">;
+  HelpText<"Disallow generation of data access to code sections (AArch64/ARM only)">;
 def mno_execute_only : Flag<["-"], "mno-execute-only">, Group<m_arm_Features_Group>,
-  HelpText<"Allow generation of data access to code sections (ARM only)">;
+  HelpText<"Allow generation of data access to code sections (AArch64/ARM only)">;
 let Flags = [TargetSpecific] in {
 def mtp_mode_EQ : Joined<["-"], "mtp=">, Group<m_arm_Features_Group>, Values<"soft,cp15,tpidrurw,tpidruro,tpidrprw,el0,el1,el2,el3,tpidr_el0,tpidr_el1,tpidr_el2,tpidr_el3,tpidrro_el0">,
   HelpText<"Thread pointer access method. "
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
index 1e2ac4e501bafd1..1248fea50f9de2b 100644
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -332,6 +332,17 @@ void aarch64::getAArch64TargetFeatures(const Driver &D,
   } else if (Triple.isOSOpenBSD())
     Features.push_back("+strict-align");
 
+  // Generate execute-only output (no data access to code sections).
+  // This only makes sense for the compiler, not for the assembler.
+  if (!ForAS) {
+    if (Arg *A = Args.getLastArg(options::OPT_mexecute_only,
+                                 options::OPT_mno_execute_only)) {
+      if (A->getOption().matches(options::OPT_mexecute_only)) {
+        Features.push_back("+execute-only");
+      }
+    }
+  }
+
   if (Args.hasArg(options::OPT_ffixed_x1))
     Features.push_back("+reserve-x1");
 
diff --git a/clang/test/CodeGen/aarch64-execute-only.c b/clang/test/CodeGen/aarch64-execute-only.c
new file mode 100644
index 000000000000000..d885e954166f674
--- /dev/null
+++ b/clang/test/CodeGen/aarch64-execute-only.c
@@ -0,0 +1,24 @@
+// RUN: %clang -target aarch64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mexecute-only %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mexecute-only -mno-execute-only %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+
+// -mpure-code flag for GCC compatibility
+// RUN: %clang -target aarch64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mpure-code %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mpure-code -mno-pure-code %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// CHECK-NO-EXECUTE-ONLY-NOT: "+execute-only"
+// CHECK-EXECUTE-ONLY: "+execute-only"
+
+void a() {}
diff --git a/clang/test/Driver/aarch64-execute-only.c b/clang/test/Driver/aarch64-execute-only.c
new file mode 100644
index 000000000000000..67c6d4a5eb06699
--- /dev/null
+++ b/clang/test/Driver/aarch64-execute-only.c
@@ -0,0 +1,6 @@
+// RUN: %clang --sysroot=%S/Inputs -c -fdriver-only -Werror --target=aarch64-unknown-linux-gnu \
+// RUN:   -mexecute-only %s 2>&1 | count 0
+
+// RUN: %clang -### --target=aarch64-unknown-linux-gnu -x assembler -mexecute-only %s -c -### 2>&1 \
+// RUN:    | FileCheck %s --check-prefix=CHECK-NO-EXECUTE-ONLY-ASM
+// CHECK-NO-EXECUTE-ONLY-ASM: warning: argument unused during compilation: '-mexecute-only'
diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index 429dc51b3356d68..cb3b75cbd27a7be 100644
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -1052,7 +1052,6 @@
 // RUN: not %clang --target=x86_64-sie-ps5 -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-TARGET
 // RUN: not %clang --target=x86_64-sie-ps5 -fsanitize=function -fsanitize=kcfi %s -### 2>&1 | FileCheck %s  --check-prefix=CHECK-UBSAN-KCFI-TARGET --check-prefix=CHECK-UBSAN-FUNCTION-TARGET
 // RUN: %clang --target=x86_64-sie-ps5 -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED
-// CHECK-UBSAN-UNDEFINED: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound),?){17}"}}
 
 // RUN: not %clang --target=armv6t2-eabi -mexecute-only -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY
 // RUN: not %clang --target=armv6t2-eabi -mpure-code -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MPURE-CODE
@@ -1060,12 +1059,19 @@
 // RUN: not %clang --target=armv6t2-eabi -mpure-code -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MPURE-CODE
 // RUN: %clang --target=armv6t2-eabi -mexecute-only -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED-VPTR
 
+// RUN: not %clang --target=aarch64 -mexecute-only -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY
+// RUN: not %clang --target=aarch64 -mpure-code -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MPURE-CODE
+// RUN: not %clang --target=aarch64 -mexecute-only -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MEXECUTE-ONLY
+// RUN: not %clang --target=aarch64 -mpure-code -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MPURE-CODE
+// RUN: %clang --target=aarch64 -mexecute-only -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED
+
 // CHECK-UBSAN-KCFI-TARGET-DAG: error: unsupported option '-fsanitize=kcfi' for target 'x86_64-sie-ps5'
 // CHECK-UBSAN-KCFI-MEXECUTE-ONLY-DAG: error: invalid argument '-fsanitize=kcfi' not allowed with '-mexecute-only'
 // CHECK-UBSAN-KCFI-MPURE-CODE-DAG: error: invalid argument '-fsanitize=kcfi' not allowed with '-mpure-code'
 // CHECK-UBSAN-FUNCTION-TARGET-DAG: error: unsupported option '-fsanitize=function' for target 'x86_64-sie-ps5'
 // CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY-DAG: error: invalid argument '-fsanitize=function' not allowed with '-mexecute-only'
 // CHECK-UBSAN-FUNCTION-MPURE-CODE-DAG: error: invalid argument '-fsanitize=function' not allowed with '-mpure-code'
+// CHECK-UBSAN-UNDEFINED: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound),?){17}"}}
 // CHECK-UBSAN-UNDEFINED-VPTR: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound|vptr),?){18}"}}
 
 // * Test BareMetal toolchain sanitizer support *
diff --git a/llvm/include/llvm/BinaryFormat/ELF.h b/llvm/include/llvm/BinaryFormat/ELF.h
index 8853c4a88b0b593..a5979d029a9eafd 100644
--- a/llvm/include/llvm/BinaryFormat/ELF.h
+++ b/llvm/include/llvm/BinaryFormat/ELF.h
@@ -1300,7 +1300,10 @@ enum : unsigned {
   SHF_MIPS_STRING = 0x80000000,
 
   // Make code section unreadable when in execute-only mode
-  SHF_ARM_PURECODE = 0x20000000
+  SHF_ARM_PURECODE = 0x20000000,
+
+  // Section contains only program instructions and no program data.
+  SHF_AARCH64_PURECODE = 0x20000000
 };
 
 // Section Group Flags
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3c2c7c8c9fed69a..6cfebca9a4d576e 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -547,7 +547,7 @@ static unsigned getELFSectionType(StringRef Name, SectionKind K) {
   return ELF::SHT_PROGBITS;
 }
 
-static unsigned getELFSectionFlags(SectionKind K) {
+static unsigned getELFSectionFlags(SectionKind K, const Triple &T) {
   unsigned Flags = 0;
 
   if (!K.isMetadata() && !K.isExclude())
@@ -559,9 +559,12 @@ static unsigned getELFSectionFlags(SectionKind K) {
   if (K.isText())
     Flags |= ELF::SHF_EXECINSTR;
 
-  if (K.isExecuteOnly())
+  if ((T.isARM() || T.isThumb()) && K.isExecuteOnly())
     Flags |= ELF::SHF_ARM_PURECODE;
 
+  if (T.isAArch64() && K.isExecuteOnly())
+    Flags |= ELF::SHF_AARCH64_PURECODE;
+
   if (K.isWriteable())
     Flags |= ELF::SHF_WRITE;
 
@@ -840,7 +843,7 @@ static MCSection *selectExplicitSectionGlobal(const GlobalObject *GO,
   // Infer section flags from the section name if we can.
   Kind = getELFKindForNamedSection(SectionName, Kind);
 
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   auto [Group, IsComdat, ExtraFlags] = getGlobalObjectInfo(GO, TM);
   Flags |= ExtraFlags;
 
@@ -947,7 +950,7 @@ static MCSection *selectELFSectionForGlobal(
 
 MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
     const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
 
   // If we have -ffunction-section or -fdata-section then we should emit the
   // global value to a uniqued section specifically for it.
@@ -967,7 +970,7 @@ MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
 MCSection *TargetLoweringObjectFileELF::getUniqueSectionForFunction(
     const Function &F, const TargetMachine &TM) const {
   SectionKind Kind = SectionKind::getText();
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   // If the function's section names is pre-determined via pragma or a
   // section attribute, call selectExplicitSectionGlobal.
   if (F.hasSection())
diff --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
index b58210b3c268e99..99b13c68a9966c7 100644
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -328,9 +328,12 @@ static unsigned parseSectionFlags(const Triple &TT, StringRef flagsStr,
       flags |= ELF::XCORE_SHF_DP_SECTION;
       break;
     case 'y':
-      if (!(TT.isARM() || TT.isThumb()))
+      if (TT.isARM() || TT.isThumb())
+        flags |= ELF::SHF_ARM_PURECODE;
+      else if (TT.isAArch64())
+        flags |= ELF::SHF_AARCH64_PURECODE;
+      else
         return -1U;
-      flags |= ELF::SHF_ARM_PURECODE;
       break;
     case 's':
       if (TT.getArch() != Triple::hexagon)
diff --git a/llvm/lib/MC/MCSectionELF.cpp b/llvm/lib/MC/MCSectionELF.cpp
index 25e62b70b5e2a0c..72a959b1c920825 100644
--- a/llvm/lib/MC/MCSectionELF.cpp
+++ b/llvm/lib/MC/MCSectionELF.cpp
@@ -118,6 +118,9 @@ void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
   } else if (T.isARM() || T.isThumb()) {
     if (Flags & ELF::SHF_ARM_PURECODE)
       OS << 'y';
+  } else if (T.isAArch64()) {
+    if (Flags & ELF::SHF_AARCH64_PURECODE)
+      OS << 'y';
   } else if (Arch == Triple::hexagon) {
     if (Flags & ELF::SHF_HEX_GPREL)
       OS << 's';
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index 539834fc8d4dbfe..05e4d85b2ea5d24 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -803,6 +803,9 @@ void ScalarBitSetTraits<ELFYAML::ELF_SHF>::bitset(IO &IO,
     break;
   }
   switch (Object->getMachine()) {
+  case ELF::EM_AARCH64:
+    BCase(SHF_AARCH64_PURECODE);
+    break;
   case ELF::EM_ARM:
     BCase(SHF_ARM_PURECODE);
     break;
diff --git a/llvm/lib/Target/AArch64/AArch64Features.td b/llvm/lib/Target/AArch64/AArch64Features.td
index 20db70ee38572f2..7c95ba662938d9f 100644
--- a/llvm/lib/Target/AArch64/AArch64Features.td
+++ b/llvm/lib/Target/AArch64/AArch64Features.td
@@ -635,6 +635,11 @@ def FeatureStrictAlign : SubtargetFeature<"strict-align",
                                           "Disallow all unaligned memory "
                                           "access">;
 
+def FeatureExecuteOnly : SubtargetFeature<"execute-only",
+                                          "GenExecuteOnly", "true",
+                                          "Enable the generation of "
+                                          "execute only code.">;
+
 foreach i = {1-7,9-15,18,20-28} in
     def FeatureReserveX#i : SubtargetFeature<"reserve-x"#i, "ReserveXRegister["#i#"]", "true",
                                              "Reserve X"#i#", making it unavailable "
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index 8729fd4b802c8eb..434ae32502d484b 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -148,3 +148,29 @@ MCSymbol *AArch64_MachoTargetObjectFile::getAuthPtrSlotSymbol(
   return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, MachOMMI, RawSym,
                                     Key, Discriminator);
 }
+
+static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind Kind,
+                                  const TargetMachine &TM) {
+  if (const Function *F = dyn_cast<Function>(GO))
+    if (TM.getSubtarget<AArch64Subtarget>(*F).genExecuteOnly() && Kind.isText())
+      return true;
+  return false;
+}
+
+MCSection *AArch64_ELFTargetObjectFile::getExplicitSectionGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  // Set execute-only access for the explicit section
+  if (isExecuteOnlyFunction(GO, Kind, TM))
+    Kind = SectionKind::getExecuteOnly();
+
+  return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, Kind, TM);
+}
+
+MCSection *AArch64_ELFTargetObjectFile::SelectSectionForGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  // Set execute-only access for the explicit section
+  if (isExecuteOnlyFunction(GO, Kind, TM))
+    Kind = SectionKind::getExecuteOnly();
+
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
+}
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
index 0c822ac84f200c7..3e9cd51b742a29c 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
@@ -39,6 +39,12 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
   void emitPersonalityValueImpl(MCStreamer &Streamer, const DataLayout &DL,
                                 const MCSymbol *Sym,
                                 const MachineModuleInfo *MMI) const override;
+
+  MCSection *getExplicitSectionGlobal(const GlobalObject *GO, SectionKind Kind,
+                                      const TargetMachine &TM) const override;
+
+  MCSection *SelectSectionForGlobal(const GlobalObject *GO, SectionKind Kind,
+                                    const TargetMachine &TM) const override;
 };
 
 /// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index a6edcf125782b2c..284278e34f8b4d0 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -262,6 +262,10 @@ bool AArch64TTIImpl::isMultiversionedFunction(const Function &F) const {
   return F.hasFnAttribute("fmv-features");
 }
 
+const FeatureBitset AArch64TTIImpl::InlineInverseFeatures = {
+    AArch64::FeatureExecuteOnly,
+};
+
 bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
                                          const Function *Callee) const {
   SMEAttrs CallerAttrs(*Caller), CalleeAttrs(*Callee);
@@ -284,7 +288,18 @@ bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
       return false;
   }
 
-  return BaseT::areInlineCompatible(Caller, Callee);
+  const TargetMachine &TM = getTLI()->getTargetMachine();
+  const FeatureBitset &CallerBits =
+      TM.getSubtargetImpl(*Caller)->getFeatureBits();
+  const FeatureBitset &CalleeBits =
+      TM.getSubtargetImpl(*Callee)->getFeatureBits();
+  // Adjust the feature bitsets by inverting some of the bits. This is needed
+  // for target features that represent restrictions rather than capabilities,
+  // for example "+execute-only".
+  FeatureBitset EffectiveCallerBits = CallerBits ^ InlineInverseFeatures;
+  FeatureBitset EffectiveCalleeBits = CalleeBits ^ InlineInverseFeatures;
+
+  return (EffectiveCallerBits & EffectiveCalleeBits) == EffectiveCalleeBits;
 }
 
 bool AArch64TTIImpl::areTypesABICompatible(
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
index b65e3c7a1ab20e5..481cb5511a331b7 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
@@ -48,6 +48,8 @@ class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
   const AArch64Subtarget *ST;
   const AArch64TargetLowering *TLI;
 
+  static const FeatureBitset InlineInverseFeatures;
+
   const AArch64Subtarget *getST() const { return ST; }
   const AArch64TargetLowering *getTLI() const { return TLI; }
 
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
index 6b5c5f36cbd4b27..d29d383bc231277 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
@@ -27,6 +27,7 @@
 #include "llvm/MC/MCELFStreamer.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
@@ -504,6 +505,23 @@ void AArch64TargetELFStreamer::finish() {
     }
   }
 
+  // The mix of execute-only and non-execute-only at link time is
+  // non-execute-only. To avoid the empty implicitly created .text
+  // section from making the whole .text section non-execute-only, we
+  // mark it execute-only if it is empty and there is at least one
+  // execute-only section in the object.
+  if (any_of(Asm, [](const MCSection &Sec) {
+        return cast<MCSectionELF>(Sec).getFlags() & ELF::SHF_AARCH64_PURECODE;
+      })) {
+    auto *Text =
+        static_cast<MCSectionELF *>(Ctx.getObjectFileInfo()->getTextSection());
+    for (auto &F : *Text)
+      if (auto *DF = dyn_cast<MCDataFragment>(&F))
+        if (!DF->getContents().empty())
+          return;
+    Text->setFlags(Text->getFlags() | ELF::SHF_AARCH64_PURECODE);
+  }
+
   MCSectionELF *MemtagSec = nullptr;
   for (const MCSymbol &Symbol : Asm.symbols()) {
     const auto &Sym = cast<MCSymbolELF>(Symbol);
diff --git a/llvm/test/CodeGen/AArch64/execute-only-section.ll b/llvm/test/CodeGen/AArch64/execute-only-section.ll
new file mode 100644
index 000000000000000..15a270b07975e69
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/execute-only-section.ll
@@ -0,0 +1,21 @@
+; RUN: llc -mtriple=aarch64 -mattr=+execute-only %s -o - | FileCheck %s
+
+; CHECK:     .section .text,"axy",@progbits,unique,0
+; CHECK-NOT: .section
+; CHECK-NOT: .text
+; CHECK:     .globl test_SectionForGlobal
+; CHECK:     .type test_SectionForGlobal,@function
+define void @test_SectionForGlobal() {
+entry:
+  ret void
+}
+
+; CHECK:     .section .test,"axy",@progbits
+; CHECK-NOT: .section
+; CHECK-NOT: .text
+; CHECK:     .globl test_ExplicitSectionForGlobal
+; CHECK:     .type test_ExplicitSectionForGlobal,@function
+define void @test_ExplicitSectionForGlobal() section ".test" {
+entry:
+  ret void
+}
diff --git a/llvm/test/MC/ELF/AArch64/execute-only-populated-text-section.s b/llvm/test/MC/ELF/AArch64/execute-only-populated-text-section....
[truncated]

llvmbot · 2025-02-04T14:14:20Z

@llvm/pr-subscribers-llvm-binary-utilities

Author: Csanád Hajdú (Il-Capitano)

Changes

Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304

The general implementation follows the existing one for ARM targets. Simlarly to ARM targets, generating object files with the SHF_AARCH64_PURECODE flag set is enabled by the -mexecute-only/-mpure-code driver flag.

Depends on #125687. The changes in that PR are included here as well for now, but will be removed once that gets merged.

Patch is 26.08 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/125688.diff

23 Files Affected:

(modified) clang/include/clang/Driver/Options.td (+2-2)
(modified) clang/lib/Driver/ToolChains/Arch/AArch64.cpp (+11)
(added) clang/test/CodeGen/aarch64-execute-only.c (+24)
(added) clang/test/Driver/aarch64-execute-only.c (+6)
(modified) clang/test/Driver/fsanitize.c (+7-1)
(modified) llvm/include/llvm/BinaryFormat/ELF.h (+4-1)
(modified) llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp (+8-5)
(modified) llvm/lib/MC/MCParser/ELFAsmParser.cpp (+5-2)
(modified) llvm/lib/MC/MCSectionELF.cpp (+3)
(modified) llvm/lib/ObjectYAML/ELFYAML.cpp (+3)
(modified) llvm/lib/Target/AArch64/AArch64Features.td (+5)
(modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp (+26)
(modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.h (+6)
(modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp (+16-1)
(modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h (+2)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp (+18)
(added) llvm/test/CodeGen/AArch64/execute-only-section.ll (+21)
(added) llvm/test/MC/ELF/AArch64/execute-only-populated-text-section.s (+27)
(added) llvm/test/MC/ELF/AArch64/execute-only-section.s (+43)
(added) llvm/test/MC/ELF/AArch64/execute-only-text-section-data.s (+27)
(modified) llvm/test/MC/ELF/section-flags-unknown.s (+3)
(modified) llvm/test/Transforms/Inline/AArch64/inline-target-attr.ll (+25)
(modified) llvm/tools/llvm-readobj/ELFDumper.cpp (+8)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 0ab923fcdd5838c..028d74c9711d1f0 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4677,9 +4677,9 @@ def mno_long_calls : Flag<["-"], "mno-long-calls">, Group<m_Group>,
   HelpText<"Restore the default behaviour of not generating long calls">;
 } // let Flags = [TargetSpecific]
 def mexecute_only : Flag<["-"], "mexecute-only">, Group<m_arm_Features_Group>,
-  HelpText<"Disallow generation of data access to code sections (ARM only)">;
+  HelpText<"Disallow generation of data access to code sections (AArch64/ARM only)">;
 def mno_execute_only : Flag<["-"], "mno-execute-only">, Group<m_arm_Features_Group>,
-  HelpText<"Allow generation of data access to code sections (ARM only)">;
+  HelpText<"Allow generation of data access to code sections (AArch64/ARM only)">;
 let Flags = [TargetSpecific] in {
 def mtp_mode_EQ : Joined<["-"], "mtp=">, Group<m_arm_Features_Group>, Values<"soft,cp15,tpidrurw,tpidruro,tpidrprw,el0,el1,el2,el3,tpidr_el0,tpidr_el1,tpidr_el2,tpidr_el3,tpidrro_el0">,
   HelpText<"Thread pointer access method. "
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
index 1e2ac4e501bafd1..1248fea50f9de2b 100644
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -332,6 +332,17 @@ void aarch64::getAArch64TargetFeatures(const Driver &D,
   } else if (Triple.isOSOpenBSD())
     Features.push_back("+strict-align");
 
+  // Generate execute-only output (no data access to code sections).
+  // This only makes sense for the compiler, not for the assembler.
+  if (!ForAS) {
+    if (Arg *A = Args.getLastArg(options::OPT_mexecute_only,
+                                 options::OPT_mno_execute_only)) {
+      if (A->getOption().matches(options::OPT_mexecute_only)) {
+        Features.push_back("+execute-only");
+      }
+    }
+  }
+
   if (Args.hasArg(options::OPT_ffixed_x1))
     Features.push_back("+reserve-x1");
 
diff --git a/clang/test/CodeGen/aarch64-execute-only.c b/clang/test/CodeGen/aarch64-execute-only.c
new file mode 100644
index 000000000000000..d885e954166f674
--- /dev/null
+++ b/clang/test/CodeGen/aarch64-execute-only.c
@@ -0,0 +1,24 @@
+// RUN: %clang -target aarch64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mexecute-only %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mexecute-only -mno-execute-only %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+
+// -mpure-code flag for GCC compatibility
+// RUN: %clang -target aarch64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mpure-code %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY
+
+// RUN: %clang -target aarch64 -### -mpure-code -mno-pure-code %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY
+
+// CHECK-NO-EXECUTE-ONLY-NOT: "+execute-only"
+// CHECK-EXECUTE-ONLY: "+execute-only"
+
+void a() {}
diff --git a/clang/test/Driver/aarch64-execute-only.c b/clang/test/Driver/aarch64-execute-only.c
new file mode 100644
index 000000000000000..67c6d4a5eb06699
--- /dev/null
+++ b/clang/test/Driver/aarch64-execute-only.c
@@ -0,0 +1,6 @@
+// RUN: %clang --sysroot=%S/Inputs -c -fdriver-only -Werror --target=aarch64-unknown-linux-gnu \
+// RUN:   -mexecute-only %s 2>&1 | count 0
+
+// RUN: %clang -### --target=aarch64-unknown-linux-gnu -x assembler -mexecute-only %s -c -### 2>&1 \
+// RUN:    | FileCheck %s --check-prefix=CHECK-NO-EXECUTE-ONLY-ASM
+// CHECK-NO-EXECUTE-ONLY-ASM: warning: argument unused during compilation: '-mexecute-only'
diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index 429dc51b3356d68..cb3b75cbd27a7be 100644
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -1052,7 +1052,6 @@
 // RUN: not %clang --target=x86_64-sie-ps5 -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-TARGET
 // RUN: not %clang --target=x86_64-sie-ps5 -fsanitize=function -fsanitize=kcfi %s -### 2>&1 | FileCheck %s  --check-prefix=CHECK-UBSAN-KCFI-TARGET --check-prefix=CHECK-UBSAN-FUNCTION-TARGET
 // RUN: %clang --target=x86_64-sie-ps5 -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED
-// CHECK-UBSAN-UNDEFINED: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound),?){17}"}}
 
 // RUN: not %clang --target=armv6t2-eabi -mexecute-only -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY
 // RUN: not %clang --target=armv6t2-eabi -mpure-code -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MPURE-CODE
@@ -1060,12 +1059,19 @@
 // RUN: not %clang --target=armv6t2-eabi -mpure-code -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MPURE-CODE
 // RUN: %clang --target=armv6t2-eabi -mexecute-only -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED-VPTR
 
+// RUN: not %clang --target=aarch64 -mexecute-only -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY
+// RUN: not %clang --target=aarch64 -mpure-code -fsanitize=function %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-FUNCTION-MPURE-CODE
+// RUN: not %clang --target=aarch64 -mexecute-only -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MEXECUTE-ONLY
+// RUN: not %clang --target=aarch64 -mpure-code -fsanitize=kcfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-KCFI-MPURE-CODE
+// RUN: %clang --target=aarch64 -mexecute-only -fsanitize=undefined %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-UBSAN-UNDEFINED
+
 // CHECK-UBSAN-KCFI-TARGET-DAG: error: unsupported option '-fsanitize=kcfi' for target 'x86_64-sie-ps5'
 // CHECK-UBSAN-KCFI-MEXECUTE-ONLY-DAG: error: invalid argument '-fsanitize=kcfi' not allowed with '-mexecute-only'
 // CHECK-UBSAN-KCFI-MPURE-CODE-DAG: error: invalid argument '-fsanitize=kcfi' not allowed with '-mpure-code'
 // CHECK-UBSAN-FUNCTION-TARGET-DAG: error: unsupported option '-fsanitize=function' for target 'x86_64-sie-ps5'
 // CHECK-UBSAN-FUNCTION-MEXECUTE-ONLY-DAG: error: invalid argument '-fsanitize=function' not allowed with '-mexecute-only'
 // CHECK-UBSAN-FUNCTION-MPURE-CODE-DAG: error: invalid argument '-fsanitize=function' not allowed with '-mpure-code'
+// CHECK-UBSAN-UNDEFINED: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound),?){17}"}}
 // CHECK-UBSAN-UNDEFINED-VPTR: "-fsanitize={{((alignment|array-bounds|bool|builtin|enum|float-cast-overflow|integer-divide-by-zero|nonnull-attribute|null|pointer-overflow|return|returns-nonnull-attribute|shift-base|shift-exponent|signed-integer-overflow|unreachable|vla-bound|vptr),?){18}"}}
 
 // * Test BareMetal toolchain sanitizer support *
diff --git a/llvm/include/llvm/BinaryFormat/ELF.h b/llvm/include/llvm/BinaryFormat/ELF.h
index 8853c4a88b0b593..a5979d029a9eafd 100644
--- a/llvm/include/llvm/BinaryFormat/ELF.h
+++ b/llvm/include/llvm/BinaryFormat/ELF.h
@@ -1300,7 +1300,10 @@ enum : unsigned {
   SHF_MIPS_STRING = 0x80000000,
 
   // Make code section unreadable when in execute-only mode
-  SHF_ARM_PURECODE = 0x20000000
+  SHF_ARM_PURECODE = 0x20000000,
+
+  // Section contains only program instructions and no program data.
+  SHF_AARCH64_PURECODE = 0x20000000
 };
 
 // Section Group Flags
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3c2c7c8c9fed69a..6cfebca9a4d576e 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -547,7 +547,7 @@ static unsigned getELFSectionType(StringRef Name, SectionKind K) {
   return ELF::SHT_PROGBITS;
 }
 
-static unsigned getELFSectionFlags(SectionKind K) {
+static unsigned getELFSectionFlags(SectionKind K, const Triple &T) {
   unsigned Flags = 0;
 
   if (!K.isMetadata() && !K.isExclude())
@@ -559,9 +559,12 @@ static unsigned getELFSectionFlags(SectionKind K) {
   if (K.isText())
     Flags |= ELF::SHF_EXECINSTR;
 
-  if (K.isExecuteOnly())
+  if ((T.isARM() || T.isThumb()) && K.isExecuteOnly())
     Flags |= ELF::SHF_ARM_PURECODE;
 
+  if (T.isAArch64() && K.isExecuteOnly())
+    Flags |= ELF::SHF_AARCH64_PURECODE;
+
   if (K.isWriteable())
     Flags |= ELF::SHF_WRITE;
 
@@ -840,7 +843,7 @@ static MCSection *selectExplicitSectionGlobal(const GlobalObject *GO,
   // Infer section flags from the section name if we can.
   Kind = getELFKindForNamedSection(SectionName, Kind);
 
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   auto [Group, IsComdat, ExtraFlags] = getGlobalObjectInfo(GO, TM);
   Flags |= ExtraFlags;
 
@@ -947,7 +950,7 @@ static MCSection *selectELFSectionForGlobal(
 
 MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
     const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
 
   // If we have -ffunction-section or -fdata-section then we should emit the
   // global value to a uniqued section specifically for it.
@@ -967,7 +970,7 @@ MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
 MCSection *TargetLoweringObjectFileELF::getUniqueSectionForFunction(
     const Function &F, const TargetMachine &TM) const {
   SectionKind Kind = SectionKind::getText();
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   // If the function's section names is pre-determined via pragma or a
   // section attribute, call selectExplicitSectionGlobal.
   if (F.hasSection())
diff --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
index b58210b3c268e99..99b13c68a9966c7 100644
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -328,9 +328,12 @@ static unsigned parseSectionFlags(const Triple &TT, StringRef flagsStr,
       flags |= ELF::XCORE_SHF_DP_SECTION;
       break;
     case 'y':
-      if (!(TT.isARM() || TT.isThumb()))
+      if (TT.isARM() || TT.isThumb())
+        flags |= ELF::SHF_ARM_PURECODE;
+      else if (TT.isAArch64())
+        flags |= ELF::SHF_AARCH64_PURECODE;
+      else
         return -1U;
-      flags |= ELF::SHF_ARM_PURECODE;
       break;
     case 's':
       if (TT.getArch() != Triple::hexagon)
diff --git a/llvm/lib/MC/MCSectionELF.cpp b/llvm/lib/MC/MCSectionELF.cpp
index 25e62b70b5e2a0c..72a959b1c920825 100644
--- a/llvm/lib/MC/MCSectionELF.cpp
+++ b/llvm/lib/MC/MCSectionELF.cpp
@@ -118,6 +118,9 @@ void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
   } else if (T.isARM() || T.isThumb()) {
     if (Flags & ELF::SHF_ARM_PURECODE)
       OS << 'y';
+  } else if (T.isAArch64()) {
+    if (Flags & ELF::SHF_AARCH64_PURECODE)
+      OS << 'y';
   } else if (Arch == Triple::hexagon) {
     if (Flags & ELF::SHF_HEX_GPREL)
       OS << 's';
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index 539834fc8d4dbfe..05e4d85b2ea5d24 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -803,6 +803,9 @@ void ScalarBitSetTraits<ELFYAML::ELF_SHF>::bitset(IO &IO,
     break;
   }
   switch (Object->getMachine()) {
+  case ELF::EM_AARCH64:
+    BCase(SHF_AARCH64_PURECODE);
+    break;
   case ELF::EM_ARM:
     BCase(SHF_ARM_PURECODE);
     break;
diff --git a/llvm/lib/Target/AArch64/AArch64Features.td b/llvm/lib/Target/AArch64/AArch64Features.td
index 20db70ee38572f2..7c95ba662938d9f 100644
--- a/llvm/lib/Target/AArch64/AArch64Features.td
+++ b/llvm/lib/Target/AArch64/AArch64Features.td
@@ -635,6 +635,11 @@ def FeatureStrictAlign : SubtargetFeature<"strict-align",
                                           "Disallow all unaligned memory "
                                           "access">;
 
+def FeatureExecuteOnly : SubtargetFeature<"execute-only",
+                                          "GenExecuteOnly", "true",
+                                          "Enable the generation of "
+                                          "execute only code.">;
+
 foreach i = {1-7,9-15,18,20-28} in
     def FeatureReserveX#i : SubtargetFeature<"reserve-x"#i, "ReserveXRegister["#i#"]", "true",
                                              "Reserve X"#i#", making it unavailable "
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index 8729fd4b802c8eb..434ae32502d484b 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -148,3 +148,29 @@ MCSymbol *AArch64_MachoTargetObjectFile::getAuthPtrSlotSymbol(
   return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, MachOMMI, RawSym,
                                     Key, Discriminator);
 }
+
+static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind Kind,
+                                  const TargetMachine &TM) {
+  if (const Function *F = dyn_cast<Function>(GO))
+    if (TM.getSubtarget<AArch64Subtarget>(*F).genExecuteOnly() && Kind.isText())
+      return true;
+  return false;
+}
+
+MCSection *AArch64_ELFTargetObjectFile::getExplicitSectionGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  // Set execute-only access for the explicit section
+  if (isExecuteOnlyFunction(GO, Kind, TM))
+    Kind = SectionKind::getExecuteOnly();
+
+  return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, Kind, TM);
+}
+
+MCSection *AArch64_ELFTargetObjectFile::SelectSectionForGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  // Set execute-only access for the explicit section
+  if (isExecuteOnlyFunction(GO, Kind, TM))
+    Kind = SectionKind::getExecuteOnly();
+
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
+}
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
index 0c822ac84f200c7..3e9cd51b742a29c 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
@@ -39,6 +39,12 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
   void emitPersonalityValueImpl(MCStreamer &Streamer, const DataLayout &DL,
                                 const MCSymbol *Sym,
                                 const MachineModuleInfo *MMI) const override;
+
+  MCSection *getExplicitSectionGlobal(const GlobalObject *GO, SectionKind Kind,
+                                      const TargetMachine &TM) const override;
+
+  MCSection *SelectSectionForGlobal(const GlobalObject *GO, SectionKind Kind,
+                                    const TargetMachine &TM) const override;
 };
 
 /// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index a6edcf125782b2c..284278e34f8b4d0 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -262,6 +262,10 @@ bool AArch64TTIImpl::isMultiversionedFunction(const Function &F) const {
   return F.hasFnAttribute("fmv-features");
 }
 
+const FeatureBitset AArch64TTIImpl::InlineInverseFeatures = {
+    AArch64::FeatureExecuteOnly,
+};
+
 bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
                                          const Function *Callee) const {
   SMEAttrs CallerAttrs(*Caller), CalleeAttrs(*Callee);
@@ -284,7 +288,18 @@ bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
       return false;
   }
 
-  return BaseT::areInlineCompatible(Caller, Callee);
+  const TargetMachine &TM = getTLI()->getTargetMachine();
+  const FeatureBitset &CallerBits =
+      TM.getSubtargetImpl(*Caller)->getFeatureBits();
+  const FeatureBitset &CalleeBits =
+      TM.getSubtargetImpl(*Callee)->getFeatureBits();
+  // Adjust the feature bitsets by inverting some of the bits. This is needed
+  // for target features that represent restrictions rather than capabilities,
+  // for example "+execute-only".
+  FeatureBitset EffectiveCallerBits = CallerBits ^ InlineInverseFeatures;
+  FeatureBitset EffectiveCalleeBits = CalleeBits ^ InlineInverseFeatures;
+
+  return (EffectiveCallerBits & EffectiveCalleeBits) == EffectiveCalleeBits;
 }
 
 bool AArch64TTIImpl::areTypesABICompatible(
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
index b65e3c7a1ab20e5..481cb5511a331b7 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
@@ -48,6 +48,8 @@ class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
   const AArch64Subtarget *ST;
   const AArch64TargetLowering *TLI;
 
+  static const FeatureBitset InlineInverseFeatures;
+
   const AArch64Subtarget *getST() const { return ST; }
   const AArch64TargetLowering *getTLI() const { return TLI; }
 
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
index 6b5c5f36cbd4b27..d29d383bc231277 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
@@ -27,6 +27,7 @@
 #include "llvm/MC/MCELFStreamer.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
@@ -504,6 +505,23 @@ void AArch64TargetELFStreamer::finish() {
     }
   }
 
+  // The mix of execute-only and non-execute-only at link time is
+  // non-execute-only. To avoid the empty implicitly created .text
+  // section from making the whole .text section non-execute-only, we
+  // mark it execute-only if it is empty and there is at least one
+  // execute-only section in the object.
+  if (any_of(Asm, [](const MCSection &Sec) {
+        return cast<MCSectionELF>(Sec).getFlags() & ELF::SHF_AARCH64_PURECODE;
+      })) {
+    auto *Text =
+        static_cast<MCSectionELF *>(Ctx.getObjectFileInfo()->getTextSection());
+    for (auto &F : *Text)
+      if (auto *DF = dyn_cast<MCDataFragment>(&F))
+        if (!DF->getContents().empty())
+          return;
+    Text->setFlags(Text->getFlags() | ELF::SHF_AARCH64_PURECODE);
+  }
+
   MCSectionELF *MemtagSec = nullptr;
   for (const MCSymbol &Symbol : Asm.symbols()) {
     const auto &Sym = cast<MCSymbolELF>(Symbol);
diff --git a/llvm/test/CodeGen/AArch64/execute-only-section.ll b/llvm/test/CodeGen/AArch64/execute-only-section.ll
new file mode 100644
index 000000000000000..15a270b07975e69
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/execute-only-section.ll
@@ -0,0 +1,21 @@
+; RUN: llc -mtriple=aarch64 -mattr=+execute-only %s -o - | FileCheck %s
+
+; CHECK:     .section .text,"axy",@progbits,unique,0
+; CHECK-NOT: .section
+; CHECK-NOT: .text
+; CHECK:     .globl test_SectionForGlobal
+; CHECK:     .type test_SectionForGlobal,@function
+define void @test_SectionForGlobal() {
+entry:
+  ret void
+}
+
+; CHECK:     .section .test,"axy",@progbits
+; CHECK-NOT: .section
+; CHECK-NOT: .text
+; CHECK:     .globl test_ExplicitSectionForGlobal
+; CHECK:     .type test_ExplicitSectionForGlobal,@function
+define void @test_ExplicitSectionForGlobal() section ".test" {
+entry:
+  ret void
+}
diff --git a/llvm/test/MC/ELF/AArch64/execute-only-populated-text-section.s b/llvm/test/MC/ELF/AArch64/execute-only-populated-text-section....
[truncated]

…#125687) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. Generating object files with the `SHF_AARCH64_PURECODE` flag set is enabled by the `+execute-only` target feature. Related PRs: * Clang: #125688 * LLD: #125689

… flag (1/3) (#125687) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. Generating object files with the `SHF_AARCH64_PURECODE` flag set is enabled by the `+execute-only` target feature. Related PRs: * Clang: llvm/llvm-project#125688 * LLD: llvm/llvm-project#125689

Il-Capitano · 2025-02-14T10:36:00Z

I've rebased this patch onto main, since #125687 has been merged, so it's now ready for review.

…llvm#125687) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. Generating object files with the `SHF_AARCH64_PURECODE` flag set is enabled by the `+execute-only` target feature. Related PRs: * Clang: llvm#125688 * LLD: llvm#125689

clang/test/Driver/aarch64-execute-only.c

…flag (3/3) (#125689) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. The output section only has the `SHF_AARCH64_PURECODE` flag set if all input sections have it set. Related PRs: * LLVM: #125687 * Clang: #125688

…LF section flag (3/3) (#125689) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. The output section only has the `SHF_AARCH64_PURECODE` flag set if all input sections have it set. Related PRs: * LLVM: llvm/llvm-project#125687 * Clang: llvm/llvm-project#125688

Il-Capitano · 2025-02-24T08:27:24Z

@smithp35 @davemgreen @paulwalker-arm @jh7370
Pinging to ask for more reviews on this, please.

jh7370 · 2025-02-24T09:57:56Z

@smithp35 @davemgreen @paulwalker-arm @jh7370 Pinging to ask for more reviews on this, please.

Sorry, this part is outside my realm of knowledge.

smithp35

LGTM. Thanks for updating the code and test to account for Multilib. Apologies for missing this last week.

Please leave some time for other reviewers to comment before merging.

…llvm#125687) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. Generating object files with the `SHF_AARCH64_PURECODE` flag set is enabled by the `+execute-only` target feature. Related PRs: * Clang: llvm#125688 * LLD: llvm#125689

Il-Capitano · 2025-02-28T14:06:31Z

@jansvoboda11 You're tagged as the compiler options maintainer for Clang, so this may be of interest to you as well.

…g (2/3) Add support for the new SHF_AARCH64_PURECODE ELF section flag: ARM-software/abi-aa#304 The general implementation follows the existing one for ARM targets. Simlarly to ARM targets, generating object files with the `SHF_AARCH64_PURECODE` flag set is enabled by the `-mexecute-only`/`-mpure-code` driver flag.

Il-Capitano · 2025-03-03T13:39:25Z

There was a merge conflict because of #121115, so I had to rebase. I also did a bit of formatting clean-up in some of the tests.

Il-Capitano · 2025-03-10T08:28:27Z

Ping.

davemgreen

LGTM

llvmbot added clang Clang issues not falling into any other category backend:AArch64 clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' mc Machine (object) code objectyaml llvm:transforms llvm:binary-utilities labels Feb 4, 2025

Il-Capitano mentioned this pull request Feb 4, 2025

[AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (1/3) #125687

Merged

Il-Capitano marked this pull request as draft February 5, 2025 09:18

DanielKristofKiss requested review from paulwalker-arm, davemgreen and jh7370 and removed request for paulwalker-arm February 7, 2025 12:45

Il-Capitano force-pushed the aarch64-execute-only-clang branch from fbb376b to a25845d Compare February 14, 2025 10:20

Il-Capitano marked this pull request as ready for review February 14, 2025 10:34

Il-Capitano mentioned this pull request Feb 14, 2025

[LLD][ELF][AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (3/3) #125689

Merged

smithp35 reviewed Feb 17, 2025

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smithp35 approved these changes Feb 24, 2025

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Il-Capitano added 3 commits March 3, 2025 11:19

Fix unused argument diagnostic emission for baremetal targets

3223272

Clean up tests

b5dafec

Il-Capitano force-pushed the aarch64-execute-only-clang branch from 3fb9937 to b5dafec Compare March 3, 2025 11:08

davemgreen approved these changes Mar 10, 2025

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davemgreen merged commit c579ec6 into llvm:main Mar 10, 2025
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Il-Capitano deleted the aarch64-execute-only-clang branch March 10, 2025 15:10

shiltian mentioned this pull request Mar 10, 2025

[AMDGPU] Fix test failures when expensive checks are enabled #130644

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