[LLD][ELF][AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (3/3) by Il-Capitano · Pull Request #125689 · llvm/llvm-project (original) (raw)

@llvm/pr-subscribers-llvm-binary-utilities
@llvm/pr-subscribers-backend-aarch64
@llvm/pr-subscribers-lld-elf
@llvm/pr-subscribers-objectyaml
@llvm/pr-subscribers-mc

@llvm/pr-subscribers-lld

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. The output section only has the SHF_AARCH64_PURECODE flag set if all input sections have it set.

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 25.54 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/125689.diff

23 Files Affected:

• (modified) lld/ELF/Config.h (+1)
• (modified) lld/ELF/Driver.cpp (+44-4)
• (modified) lld/ELF/OutputSections.cpp (+7-3)
• (modified) lld/ELF/ScriptParser.cpp (+1)
• (added) lld/test/ELF/aarch64-execute-only.s (+33)
• (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/lld/ELF/Config.h b/lld/ELF/Config.h index c2aadb2cef5200f..ecfb492522227bc 100644 --- a/lld/ELF/Config.h +++ b/lld/ELF/Config.h @@ -229,6 +229,7 @@ struct Config { StringRef zCetReport = "none"; StringRef zPauthReport = "none"; StringRef zGcsReport = "none";

• StringRef zExecuteOnlyReport = "none"; bool ltoBBAddrMap; llvm::StringRef ltoBasicBlockSections; std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace; diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp index acbc97b331b0e1c..f9c61584984a8f5 100644 --- a/lld/ELF/Driver.cpp +++ b/lld/ELF/Driver.cpp @@ -459,6 +459,8 @@ static void checkOptions(Ctx &ctx) { ErrAlways(ctx) << "-z gcs-report only supported on AArch64"; if (ctx.arg.zGcs != GcsPolicy::Implicit) ErrAlways(ctx) << "-z gcs only supported on AArch64";

• if (ctx.arg.zExecuteOnlyReport != "none")

•  ErrAlways(ctx) << "-z execute-only-report only supported on AArch64";

  }

  if (ctx.arg.emachine != EM_386 && ctx.arg.emachine != EM_X86_64 &&

@@ -1557,10 +1559,12 @@ static void readConfigs(Ctx &ctx, opt::InputArgList &args) { ErrAlways(ctx) << errPrefix << pat.takeError() << ": " << kv.first; }

• auto reports = {std::make_pair("bti-report", &ctx.arg.zBtiReport),

•              std::make_pair("cet-report", &ctx.arg.zCetReport),

•              std::make_pair("gcs-report", &ctx.arg.zGcsReport),

•              std::make_pair("pauth-report", &ctx.arg.zPauthReport)};

• auto reports = {

•  std::make_pair("bti-report", &ctx.arg.zBtiReport),

•  std::make_pair("cet-report", &ctx.arg.zCetReport),

•  std::make_pair("gcs-report", &ctx.arg.zGcsReport),

•  std::make_pair("pauth-report", &ctx.arg.zPauthReport),

•  std::make_pair("execute-only-report", &ctx.arg.zExecuteOnlyReport)};

  for (opt::Arg *arg : args.filtered(OPT_z)) { std::pair<StringRef, StringRef> option = StringRef(arg->getValue()).split('=');

@@ -2844,6 +2848,40 @@ static void readSecurityNotes(Ctx &ctx) { ctx.arg.andFeatures &= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS; }

+static void checkExecuteOnly(Ctx &ctx) {

• if (ctx.arg.emachine != EM_AARCH64)

• return;

• auto report = [&](StringRef config) -> ELFSyncStream {

• if (config == "error")

•  return {ctx, DiagLevel::Err};

• if (config == "warning")

•  return {ctx, DiagLevel::Warn};

• return {ctx, DiagLevel::None};

• };

• auto reportUnless = [&](StringRef config, bool cond) -> ELFSyncStream {

• if (cond)

•  return {ctx, DiagLevel::None};

• return report(config);

• };

• for (ELFFileBase *file : ctx.objectFiles) {

• for (InputSectionBase *section : file->getSections()) {

•  // Only check for executable sections.

•  if (!(section && section->flags & SHF_EXECINSTR))

•    continue;

•  OutputSection *outputSection = section->getOutputSection();

•  if (outputSection && outputSection->name == ".text") {

•    reportUnless(ctx.arg.zExecuteOnlyReport,

•                 section->flags & SHF_AARCH64_PURECODE)

•        << file << ": -z execute-only-report: section " << section->name

•        << " does not have SHF_AARCH64_PURECODE flag set";

•  }

• }

• } +}

• static void initSectionsAndLocalSyms(ELFFileBase *file, bool ignoreComdats) { switch (file->ekind) { case ELF32LEKind: @@ -3213,6 +3251,8 @@ template void LinkerDriver::link(opt::InputArgList &args) { ctx.script->addOrphanSections(); }

• checkExecuteOnly(ctx);

• { llvm::TimeTraceScope timeScope("Merge/finalize input sections");

diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp index a2da5543d58670f..c8dc0e5fe033528 100644 --- a/lld/ELF/OutputSections.cpp +++ b/lld/ELF/OutputSections.cpp @@ -42,7 +42,8 @@ using namespace lld::elf;

uint32_t OutputSection::getPhdrFlags() const { uint32_t ret = 0;

• if (ctx.arg.emachine != EM_ARM || !(flags & SHF_ARM_PURECODE))

• if ((ctx.arg.emachine != EM_ARM || !(flags & SHF_ARM_PURECODE)) &&

•  (ctx.arg.emachine != EM_AARCH64 || !(flags & SHF_AARCH64_PURECODE)))

  ret |= PF_R; if (flags & SHF_WRITE) ret |= PF_W; @@ -161,8 +162,11 @@ void OutputSection::commitSection(InputSection *isec) { }

  isec->parent = this;

• uint64_t andMask =

•  ctx.arg.emachine == EM_ARM ? (uint64_t)SHF_ARM_PURECODE : 0;

• uint64_t andMask = 0;
• if (ctx.arg.emachine == EM_ARM)
• andMask |= (uint64_t)SHF_ARM_PURECODE;
• if (ctx.arg.emachine == EM_AARCH64)
• andMask |= (uint64_t)SHF_AARCH64_PURECODE;

uint64_t orMask = ~andMask; uint64_t andFlags = (flags & isec->flags) & andMask; uint64_t orFlags = (flags | isec->flags) & orMask; diff --git a/lld/ELF/ScriptParser.cpp b/lld/ELF/ScriptParser.cpp index a10af9565a1d631..671a5ec4deccba3 100644 --- a/lld/ELF/ScriptParser.cpp +++ b/lld/ELF/ScriptParser.cpp @@ -1411,6 +1411,7 @@ static std::optional parseFlag(StringRef tok) { .Case(CASE_ENT(SHF_COMPRESSED)) .Case(CASE_ENT(SHF_EXCLUDE)) .Case(CASE_ENT(SHF_ARM_PURECODE))

•  .Case(CASE_ENT(SHF_AARCH64_PURECODE))
   .Default(std::nullopt);

#undef CASE_ENT } diff --git a/lld/test/ELF/aarch64-execute-only.s b/lld/test/ELF/aarch64-execute-only.s new file mode 100644 index 000000000000000..e67bbf05ff2e215 --- /dev/null +++ b/lld/test/ELF/aarch64-execute-only.s @@ -0,0 +1,33 @@ +// REQUIRES: aarch64 + +// RUN: llvm-mc -filetype=obj -triple=aarch64-linux-none %s -o %t.o +// RUN: ld.lld %t.o -o %t.so -shared +// RUN: llvm-readelf -l %t.so | FileCheck --implicit-check-not=LOAD %s + +// RUN: echo ".section .foo,"ax";
+// RUN: ret" > %t.s +// RUN: llvm-mc -filetype=obj -triple=aarch64-linux-none %t.s -o %t2.o +// RUN: ld.lld %t.o %t2.o -o %t.so -shared +// RUN: llvm-readelf -l %t.so | FileCheck --check-prefix=DIFF --implicit-check-not=LOAD %s + +// CHECK: LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x000245 0x000245 R 0x10000 +// CHECK: LOAD 0x000248 0x0000000000010248 0x0000000000010248 0x{{.}} 0x{{.}} R E 0x10000 +// CHECK: LOAD 0x00024c 0x000000000002024c 0x000000000002024c 0x{{.}} 0x{{.}} E 0x10000 +// CHECK: LOAD 0x000250 0x0000000000030250 0x0000000000030250 0x000070 0x000db0 RW 0x10000 + +// CHECK: 01 .dynsym .gnu.hash .hash .dynstr +// CHECK: 02 .text +// CHECK: 03 .foo +// CHECK: 04 .dynamic + +// DIFF: LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x00020d 0x00020d R 0x10000 +// DIFF: LOAD 0x000210 0x0000000000010210 0x0000000000010210 0x00000c 0x00000c R E 0x10000 +// DIFF: LOAD 0x000220 0x0000000000020220 0x0000000000020220 0x000070 0x000de0 RW 0x10000 + +// DIFF: 01 .dynsym .gnu.hash .hash .dynstr +// DIFF: 02 .text .foo +// DIFF: 03 .dynamic +

•    ret

•    .section .foo,"axy"

•    ret

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 ScalarBitSetTraitsELFYAML::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(GO))
• if (TM.getSubtarget(*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 { 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(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.s new file mode 100644 index 000000000000000..b0ba8a18d52b386 --- /dev/null +++ b/llvm/test/MC/ELF/AArch64/execute-only-populated-text-section.s @@ -0,0 +1,27 @@ +// RUN: llvm-mc -filetype=obj -triple aarch64-unknown-linux-gnu %s -o -
  +// RUN: | llvm-readobj -S --symbols - | FileCheck %s

•    .text

•    ret

•    .section        .text.foo,"axy"

•    ret

• +// CHECK: Section { +// CHECK: Name: .text +// CHECK-NEXT: Type: SHT_PROGBITS (0x1) +// CHECK-NEXT: Flags [ (0x6) +// CHECK-NEXT: SHF_ALLOC (0x... [truncated]