Author: Daniel Kiss Date: 2020-09-17T00:24:14+02:00 New Revision: 95e43f84b7b9c61011aece7583c0367297dd67d8
URL: https://github.com/llvm/llvm-project/commit/95e43f84b7b9c61011aece7583c0367297dd67d8 DIFF: https://github.com/llvm/llvm-project/commit/95e43f84b7b9c61011aece7583c0367297dd67d8.diff LOG: [AArch64] Add -mmark-bti-property flag. Writing the .note.gnu.property manually is error prone and hard to maintain in the assembly files. The -mmark-bti-property is for the assembler to emit the section with the GNU_PROPERTY_AARCH64_FEATURE_1_BTI. To be used when C/C++ is compiled with -mbranch-protection=bti. This patch refactors the .note.gnu.property handling. Reviewed By: chill, nickdesaulniers Differential Revision: https://reviews.llvm.org/D81930 Added: clang/test/Driver/arm64-markbti.S Modified: clang/include/clang/Driver/Options.td clang/lib/Driver/ToolChains/Clang.cpp llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h Removed: ################################################################################ diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 5b39ea513b24..d7c2496b8a5d 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -2385,6 +2385,9 @@ def mfix_cortex_a53_835769 : Flag<["-"], "mfix-cortex-a53-835769">, def mno_fix_cortex_a53_835769 : Flag<["-"], "mno-fix-cortex-a53-835769">, Group<m_aarch64_Features_Group>, HelpText<"Don't workaround Cortex-A53 erratum 835769 (AArch64 only)">; +def mmark_bti_property : Flag<["-"], "mmark-bti-property">, + Group<m_aarch64_Features_Group>, + HelpText<"Add .note.gnu.property with BTI to assembly files (AArch64 only)">; foreach i = {1-31} in def ffixed_x#i : Flag<["-"], "ffixed-x"#i>, Group<m_Group>, HelpText<"Reserve the x"#i#" register (AArch64/RISC-V only)">; diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 51056960761d..e13ffe67af89 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7018,6 +7018,15 @@ void ClangAs::ConstructJob(Compilation &C, const JobAction &JA, } break; + case llvm::Triple::aarch64: + case llvm::Triple::aarch64_32: + case llvm::Triple::aarch64_be: + if (Args.hasArg(options::OPT_mmark_bti_property)) { + CmdArgs.push_back("-mllvm"); + CmdArgs.push_back("-aarch64-mark-bti-property"); + } + break; + case llvm::Triple::riscv32: case llvm::Triple::riscv64: AddRISCVTargetArgs(Args, CmdArgs); diff --git a/clang/test/Driver/arm64-markbti.S b/clang/test/Driver/arm64-markbti.S new file mode 100644 index 000000000000..68c81d31afa3 --- /dev/null +++ b/clang/test/Driver/arm64-markbti.S @@ -0,0 +1,24 @@ +// When -mmark-bti-property is passed the generated file object gets BTI marking. +// RUN: %clang -target arm64-linux-none -mmark-bti-property -c -o - %s | llvm-readobj -n - | FileCheck -check-prefix=CHECK -check-prefix=CHECK_GEN %s +// RUN: %clang -target arm64-linux-none -DNOTE_PRESENT -c %s -o - | llvm-readobj -n - | FileCheck -check-prefix=CHECK -check-prefix=CHECK_PRESET %s +// RUN: %clang -target arm64-linux-none -mmark-bti-property -DNOTE_PRESENT -c %s -o - | llvm-readobj -n - | FileCheck -check-prefix=CHECK -check-prefix=CHECK_PRESET %s +// RUN: %clang -target arm64-linux-none -mmark-bti-property -DNOTE_PRESENT -c %s -o - 2>&1 | FileCheck -check-prefix=CHECK_WARNING %s +// +// CHECK_WARNING: The .note.gnu.property is not emitted because it is already present. +// CHECK: Name: .note.gnu.property +// CHECK: Type: NT_GNU_PROPERTY_TYPE_0 +// CHECK_GEN: aarch64 feature: BTI +// CHECK_PRESET: aarch64 feature: BTI, PAC + +#ifdef NOTE_PRESENT + .section .note.gnu.property, "a"; + .balign 8; + .long 4; + .long 0x10; + .long 0x5 + .asciz "GNU" + .long 0xc0000000 + .long 4 + .long 3 + .long 0 +#endif diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp index 8cbd60d74970..30ac7f4c0d2e 100644 --- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp +++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp @@ -223,26 +223,9 @@ void AArch64AsmPrinter::emitStartOfAsmFile(Module &M) { return; // Emit a .note.gnu.property section with the flags. - MCSection *Cur = OutStreamer->getCurrentSectionOnly(); - MCSection *Nt = MMI->getContext().getELFSection( - ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC); - OutStreamer->SwitchSection(Nt); - - // Emit the note header. - emitAlignment(Align(8)); - OutStreamer->emitInt32(4); // data size for "GNU\0" - OutStreamer->emitInt32(4 * 4); // Elf_Prop size - OutStreamer->emitInt32(ELF::NT_GNU_PROPERTY_TYPE_0); - OutStreamer->emitBytes(StringRef("GNU", 4)); // note name - - // Emit the PAC/BTI properties. - OutStreamer->emitInt32(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_AND); - OutStreamer->emitInt32(4); // data size - OutStreamer->emitInt32(Flags); // data - OutStreamer->emitInt32(0); // pad - - OutStreamer->endSection(Nt); - OutStreamer->SwitchSection(Cur); + if (auto *TS = static_cast<AArch64TargetStreamer *>( + OutStreamer->getTargetStreamer())) + TS->emitNoteSection(Flags); } void AArch64AsmPrinter::emitFunctionHeaderComment() { diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp index 48ed68f49263..f32a8f15b8a5 100644 --- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp +++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp @@ -11,12 +11,23 @@ //===----------------------------------------------------------------------===// #include "AArch64TargetStreamer.h" +#include "AArch64MCAsmInfo.h" +#include "AArch64Subtarget.h" +#include "llvm/BinaryFormat/ELF.h" #include "llvm/MC/ConstantPools.h" +#include "llvm/MC/MCContext.h" #include "llvm/MC/MCSection.h" +#include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCSubtargetInfo.h" +#include "llvm/Support/CommandLine.h" using namespace llvm; +static cl::opt<bool> MarkBTIProperty( + "aarch64-mark-bti-property", cl::Hidden, + cl::desc("Add .note.gnu.property with BTI to assembly files"), + cl::init(false)); + // // AArch64TargetStreamer Implemenation // @@ -37,8 +48,50 @@ void AArch64TargetStreamer::emitCurrentConstantPool() { ConstantPools->emitForCurrentSection(Streamer); } -// finish() - write out any non-empty assembler constant pools. -void AArch64TargetStreamer::finish() { ConstantPools->emitAll(Streamer); } +// finish() - write out any non-empty assembler constant pools and +// write out note.gnu.properties if need. +void AArch64TargetStreamer::finish() { + ConstantPools->emitAll(Streamer); + + if (MarkBTIProperty) + emitNoteSection(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI); +} + +void AArch64TargetStreamer::emitNoteSection(unsigned Flags) { + if (Flags == 0) + return; + + MCStreamer &OutStreamer = getStreamer(); + MCContext &Context = OutStreamer.getContext(); + // Emit a .note.gnu.property section with the flags. + MCSectionELF *Nt = Context.getELFSection(".note.gnu.property", ELF::SHT_NOTE, + ELF::SHF_ALLOC); + if (Nt->isRegistered()) { + SMLoc Loc; + Context.reportWarning( + Loc, + "The .note.gnu.property is not emitted because it is already present."); + return; + } + MCSection *Cur = OutStreamer.getCurrentSectionOnly(); + OutStreamer.SwitchSection(Nt); + + // Emit the note header. + OutStreamer.emitValueToAlignment(Align(8).value()); + OutStreamer.emitIntValue(4, 4); // data size for "GNU\0" + OutStreamer.emitIntValue(4 * 4, 4); // Elf_Prop size + OutStreamer.emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4); + OutStreamer.emitBytes(StringRef("GNU", 4)); // note name + + // Emit the PAC/BTI properties. + OutStreamer.emitIntValue(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_AND, 4); + OutStreamer.emitIntValue(4, 4); // data size + OutStreamer.emitIntValue(Flags, 4); // data + OutStreamer.emitIntValue(0, 4); // pad + + OutStreamer.endSection(Nt); + OutStreamer.SwitchSection(Cur); +} void AArch64TargetStreamer::emitInst(uint32_t Inst) { char Buffer[4]; diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h index c0dee085cace..09953315bbd0 100644 --- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h +++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h @@ -33,6 +33,9 @@ class AArch64TargetStreamer : public MCTargetStreamer { /// Emit contents of constant pool for the current section. void emitCurrentConstantPool(); + /// Callback used to implement the .note.gnu.property section. + void emitNoteSection(unsigned Flags); + /// Callback used to implement the .inst directive. virtual void emitInst(uint32_t Inst); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
