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[LLD][ELF] Add -z execute-only-report that checks PURECODE section flags (llvm#128883)
`-z execute-only-report` checks that all executable sections have either the SHF_AARCH64_PURECODE or SHF_ARM_PURECODE section flag set on AArch64 and ARM respectively.
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6 files changed

+143
-4
lines changed

6 files changed

+143
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‎lld/ELF/Config.h‎

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Original file line numberDiff line numberDiff line change
@@ -229,6 +229,7 @@ struct Config {
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StringRef zCetReport = "none";
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StringRef zPauthReport = "none";
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StringRef zGcsReport = "none";
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StringRef zExecuteOnlyReport = "none";
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bool ltoBBAddrMap;
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llvm::StringRef ltoBasicBlockSections;
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std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;

‎lld/ELF/Driver.cpp‎

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -406,6 +406,11 @@ static void checkOptions(Ctx &ctx) {
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ErrAlways(ctx) << "-z gcs only supported on AArch64";
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}
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if (ctx.arg.emachine != EM_AARCH64 && ctx.arg.emachine != EM_ARM &&
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ctx.arg.zExecuteOnlyReport != "none")
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ErrAlways(ctx)
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<< "-z execute-only-report only supported on AArch64 and ARM";
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if (ctx.arg.emachine != EM_PPC64) {
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if (ctx.arg.tocOptimize)
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ErrAlways(ctx) << "--toc-optimize is only supported on PowerPC64 targets";
@@ -1620,10 +1625,12 @@ static void readConfigs(Ctx &ctx, opt::InputArgList &args) {
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ErrAlways(ctx) << errPrefix << pat.takeError() << ": " << kv.first;
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}
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auto reports = {std::make_pair("bti-report", &ctx.arg.zBtiReport),
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std::make_pair("cet-report", &ctx.arg.zCetReport),
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std::make_pair("gcs-report", &ctx.arg.zGcsReport),
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std::make_pair("pauth-report", &ctx.arg.zPauthReport)};
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auto reports = {
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std::make_pair("bti-report", &ctx.arg.zBtiReport),
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std::make_pair("cet-report", &ctx.arg.zCetReport),
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std::make_pair("execute-only-report", &ctx.arg.zExecuteOnlyReport),
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std::make_pair("gcs-report", &ctx.arg.zGcsReport),
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std::make_pair("pauth-report", &ctx.arg.zPauthReport)};
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for (opt::Arg *arg : args.filtered(OPT_z)) {
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std::pair<StringRef, StringRef> option =
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StringRef(arg->getValue()).split('=');

‎lld/ELF/Writer.cpp‎

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -64,6 +64,7 @@ template <class ELFT> class Writer {
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void sortOrphanSections();
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void finalizeSections();
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void checkExecuteOnly();
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void checkExecuteOnlyReport();
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void setReservedSymbolSections();
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SmallVector<std::unique_ptr<PhdrEntry>, 0> createPhdrs(Partition &part);
@@ -323,6 +324,7 @@ template <class ELFT> void Writer<ELFT>::run() {
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// finalizeSections does that.
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finalizeSections();
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checkExecuteOnly();
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checkExecuteOnlyReport();
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// If --compressed-debug-sections is specified, compress .debug_* sections.
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// Do it right now because it changes the size of output sections.
@@ -2176,6 +2178,41 @@ template <class ELFT> void Writer<ELFT>::checkExecuteOnly() {
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"data and code";
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}
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// Check which input sections of RX output sections don't have the
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// SHF_AARCH64_PURECODE or SHF_ARM_PURECODE flag set.
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template <class ELFT> void Writer<ELFT>::checkExecuteOnlyReport() {
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if (ctx.arg.zExecuteOnlyReport == "none")
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return;
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auto reportUnless = [&](bool cond) -> ELFSyncStream {
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if (cond)
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return {ctx, DiagLevel::None};
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if (ctx.arg.zExecuteOnlyReport == "error")
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return {ctx, DiagLevel::Err};
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if (ctx.arg.zExecuteOnlyReport == "warning")
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return {ctx, DiagLevel::Warn};
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return {ctx, DiagLevel::None};
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};
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uint64_t purecodeFlag =
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ctx.arg.emachine == EM_AARCH64 ? SHF_AARCH64_PURECODE : SHF_ARM_PURECODE;
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StringRef purecodeFlagName = ctx.arg.emachine == EM_AARCH64
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? "SHF_AARCH64_PURECODE"
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: "SHF_ARM_PURECODE";
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SmallVector<InputSection *, 0> storage;
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for (OutputSection *osec : ctx.outputSections) {
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if (osec->getPhdrFlags() != (PF_R | PF_X))
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continue;
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for (InputSection *sec : getInputSections(*osec, storage)) {
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if (isa<SyntheticSection>(sec))
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continue;
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reportUnless(sec->flags & purecodeFlag)
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<< "-z execute-only-report: " << sec << " does not have "
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<< purecodeFlagName << " flag set";
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}
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}
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}
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// The linker is expected to define SECNAME_start and SECNAME_end
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// symbols for a few sections. This function defines them.
21812218
template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {

‎lld/test/ELF/aarch64-execute-only-report.s‎

Lines changed: 44 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,44 @@
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// REQUIRES: aarch64
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// RUN: rm -rf %t && mkdir %t && cd %t
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// RUN: llvm-mc --triple=aarch64 --filetype=obj %s -o a.o
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// RUN: ld.lld --defsym absolute=0xf0000000 -z execute-only-report=none --fatal-warnings a.o
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// RUN: ld.lld --defsym absolute=0xf0000000 -z execute-only-report=warning a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=WARNING %s
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// RUN: ld.lld --defsym absolute=0xf0000000 --execute-only -z execute-only-report=warning a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=WARNING %s
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// WARNING-NOT: warning: -z execute-only-report: a.o:(.text) does not have SHF_AARCH64_PURECODE flag set
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// WARNING-NOT: warning: -z execute-only-report: a.o:(.text.foo) does not have SHF_AARCH64_PURECODE flag set
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// WARNING: warning: -z execute-only-report: a.o:(.text.bar) does not have SHF_AARCH64_PURECODE flag set
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// WARNING-NOT: warning: -z execute-only-report: <internal>:({{.*}}) does not have SHF_AARCH64_PURECODE flag set
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// RUN: not ld.lld --defsym absolute=0xf0000000 -z execute-only-report=error a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=ERROR %s
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// RUN: not ld.lld --defsym absolute=0xf0000000 --execute-only -z execute-only-report=error a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=ERROR %s
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// ERROR-NOT: error: -z execute-only-report: a.o:(.text) does not have SHF_AARCH64_PURECODE flag set
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// ERROR-NOT: error: -z execute-only-report: a.o:(.text.foo) does not have SHF_AARCH64_PURECODE flag set
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// ERROR: error: -z execute-only-report: a.o:(.text.bar) does not have SHF_AARCH64_PURECODE flag set
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// ERROR-NOT: error: -z execute-only-report: <internal>:({{.*}}) does not have SHF_AARCH64_PURECODE flag set
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.section .text,"axy",@progbits,unique,0
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.globl _start
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_start:
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bl foo
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bl bar
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bl absolute
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ret
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.section .text.foo,"axy",@progbits,unique,0
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.globl foo
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foo:
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ret
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.section .text.bar,"ax",@progbits,unique,0
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.globl bar
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bar:
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ret

‎lld/test/ELF/arm-execute-only-report.s‎

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@@ -0,0 +1,40 @@
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// REQUIRES: arm
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// RUN: rm -rf %t && mkdir %t && cd %t
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// RUN: llvm-mc --triple=armv7 --filetype=obj %s -o a.o
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// RUN: ld.lld --defsym absolute=0xf0000000 -z execute-only-report=none --fatal-warnings a.o
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// RUN: ld.lld --defsym absolute=0xf0000000 -z execute-only-report=warning a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=WARNING %s
10+
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// WARNING-NOT: warning: -z execute-only-report: a.o:(.text) does not have SHF_ARM_PURECODE flag set
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// WARNING-NOT: warning: -z execute-only-report: a.o:(.text.foo) does not have SHF_ARM_PURECODE flag set
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// WARNING: warning: -z execute-only-report: a.o:(.text.bar) does not have SHF_ARM_PURECODE flag set
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// WARNING-NOT: warning: -z execute-only-report: <internal>:({{.*}}) does not have SHF_ARM_PURECODE flag set
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// RUN: not ld.lld --defsym absolute=0xf0000000 -z execute-only-report=error a.o 2>&1 | \
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// RUN: FileCheck --check-prefix=ERROR %s
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// ERROR-NOT: error: -z execute-only-report: a.o:(.text) does not have SHF_ARM_PURECODE flag set
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// ERROR-NOT: error: -z execute-only-report: a.o:(.text.foo) does not have SHF_ARM_PURECODE flag set
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// ERROR: error: -z execute-only-report: a.o:(.text.bar) does not have SHF_ARM_PURECODE flag set
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// ERROR-NOT: error: -z execute-only-report: <internal>:({{.*}}) does not have SHF_ARM_PURECODE flag set
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.section .text,"axy",%progbits,unique,0
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.globl _start
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_start:
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bl foo
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bl bar
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bl absolute
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bx lr
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.section .text.foo,"axy",%progbits,unique,0
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.globl foo
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foo:
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bx lr
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.section .text.bar,"ax",%progbits,unique,0
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.globl bar
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bar:
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bx lr

‎lld/test/ELF/target-specific-options.s‎

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Original file line numberDiff line numberDiff line change
@@ -13,5 +13,15 @@
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# RUN: not ld.lld %t --toc-optimize -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR-TOC
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# ERR-TOC: error: --toc-optimize is only supported on PowerPC64 targets
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# RUN: not ld.lld %t -z execute-only-report=warning -o /dev/null 2>&1 | \
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# RUN: FileCheck %s --check-prefix=ERR-EXECUTE-ONLY
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# RUN: not ld.lld %t -z execute-only-report=error -o /dev/null 2>&1 | \
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# RUN: FileCheck %s --check-prefix=ERR-EXECUTE-ONLY
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# ERR-EXECUTE-ONLY: error: -z execute-only-report only supported on AArch64 and ARM
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# RUN: not ld.lld %t -z execute-only-report=foo -o /dev/null 2>&1 | \
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# RUN: FileCheck %s --check-prefix=ERR-EXECUTE-ONLY-INVALID
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# ERR-EXECUTE-ONLY-INVALID: error: unknown -z execute-only-report= value: foo
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.globl _start
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_start:

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