From d53e61863d48a07ce285d5b0a36abc67583023bd Mon Sep 17 00:00:00 2001 From: Momchil Velikov Date: Fri, 13 Dec 2019 17:37:22 +0000 Subject: [PATCH] [AArch64] Emit PAC/BTI .note.gnu.property flags This patch make LLVM emit the processor specific program property types defined in AArch64 ELF spec https://developer.arm.com/docs/ihi0056/f/elf-for-the-arm-64-bit-architecture-aarch64-abi-2019q2-documentation A file containing no functions gets both property flags. Otherwise, a property is set iff all the functions in the file have the corresponding attribute. Patch by Daniel Kiss and Momchil Velikov. Differential Revision: https://reviews.llvm.org/D71019 --- llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp | 60 +++++++++++++++++++ .../AArch64/note-gnu-property-pac-bti-0.ll | 14 +++++ .../AArch64/note-gnu-property-pac-bti-1.ll | 18 ++++++ .../AArch64/note-gnu-property-pac-bti-2.ll | 18 ++++++ .../AArch64/note-gnu-property-pac-bti-3.ll | 18 ++++++ .../AArch64/note-gnu-property-pac-bti-4.ll | 25 ++++++++ .../AArch64/note-gnu-property-pac-bti-5.ll | 26 ++++++++ .../AArch64/note-gnu-property-pac-bti-6.ll | 22 +++++++ .../AArch64/note-gnu-property-pac-bti-7.ll | 23 +++++++ .../AArch64/note-gnu-property-pac-bti-8.ll | 21 +++++++ 10 files changed, 245 insertions(+) create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-0.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-1.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-2.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-3.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-4.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-5.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-6.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-7.ll create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-8.ll diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp index 7ea7915c2ca6..11f3273760d3 100644 --- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp +++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp @@ -84,6 +84,7 @@ public: return MCInstLowering.lowerOperand(MO, MCOp); } + void EmitStartOfAsmFile(Module &M) override; void EmitJumpTableInfo() override; void emitJumpTableEntry(const MachineJumpTableInfo *MJTI, const MachineBasicBlock *MBB, unsigned JTI); @@ -181,6 +182,65 @@ private: } // end anonymous namespace +void AArch64AsmPrinter::EmitStartOfAsmFile(Module &M) { + if (!TM.getTargetTriple().isOSBinFormatELF()) + return; + + // Assemble feature flags that may require creation of a note section. + unsigned Flags = ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI | + ELF::GNU_PROPERTY_AARCH64_FEATURE_1_PAC; + + if (any_of(M, [](const Function &F) { + return !F.isDeclaration() && + !F.hasFnAttribute("branch-target-enforcement"); + })) { + Flags &= ~ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI; + } + + if ((Flags & ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI) == 0 && + any_of(M, [](const Function &F) { + return F.hasFnAttribute("branch-target-enforcement"); + })) { + errs() << "warning: some functions compiled with BTI and some compiled " + "without BTI\n" + << "warning: not setting BTI in feature flags\n"; + } + + if (any_of(M, [](const Function &F) { + if (F.isDeclaration()) + return false; + Attribute A = F.getFnAttribute("sign-return-address"); + return !A.isStringAttribute() || A.getValueAsString() == "none"; + })) { + Flags &= ~ELF::GNU_PROPERTY_AARCH64_FEATURE_1_PAC; + } + + if (Flags == 0) + 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->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 AArch64AsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI) { EmitSled(MI, SledKind::FUNCTION_ENTER); diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-0.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-0.ll new file mode 100644 index 000000000000..cd5b99765d1b --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-0.ll @@ -0,0 +1,14 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ +@x = common dso_local global i32 0, align 4 + +attributes #0 = { "branch-target-enforcement" } + +; Both attributes present in a file with no functions. +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 3 + +; OBJ: Properties: aarch64 feature: BTI, PAC diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-1.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-1.ll new file mode 100644 index 000000000000..3be749761726 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-1.ll @@ -0,0 +1,18 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +attributes #0 = { "branch-target-enforcement" } + +; BTI attribute present +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 1 + +; OBJ: Properties: aarch64 feature: BTI diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-2.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-2.ll new file mode 100644 index 000000000000..bb63a8629765 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-2.ll @@ -0,0 +1,18 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +attributes #0 = { "sign-return-address"="all" } + +; PAC attribute present +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 2 + +; OBJ: Properties: aarch64 feature: PAC diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-3.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-3.ll new file mode 100644 index 000000000000..98a8e5e758d3 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-3.ll @@ -0,0 +1,18 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +attributes #0 = { "branch-target-enforcement" "sign-return-address"="non-leaf" } + +; Both attribute present +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 3 + +; OBJ: Properties: aarch64 feature: BTI, PAC diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-4.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-4.ll new file mode 100644 index 000000000000..b9179fd26ae4 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-4.ll @@ -0,0 +1,25 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +define dso_local i32 @g() #1 { +entry: + ret i32 0 +} + +attributes #0 = { "branch-target-enforcement" "sign-return-address"="non-leaf" } + +attributes #1 = { "branch-target-enforcement" } + +; Only the common atttribute (BTI) +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 1 + +; OBJ: Properties: aarch64 feature: BTI diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-5.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-5.ll new file mode 100644 index 000000000000..8959c16a13a1 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-5.ll @@ -0,0 +1,26 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - 2>&1 | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +define dso_local i32 @g() #1 { +entry: + ret i32 0 +} + +attributes #0 = { "branch-target-enforcement" "sign-return-address"="non-leaf" } + +attributes #1 = { "sign-return-address"="all" } + +; Only the common atttribute (PAC) +; ASM: warning: not setting BTI in feature flags +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 2 + +; OBJ: Properties: aarch64 feature: PAC diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-6.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-6.ll new file mode 100644 index 000000000000..b57a23b97b2c --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-6.ll @@ -0,0 +1,22 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf -S | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +define dso_local i32 @g() #1 { +entry: + ret i32 0 +} + +attributes #0 = { "sign-return-address"="non-leaf" } + +attributes #1 = { "sign-return-address"="none" } + +; No common attribute, no note section +; ASM-NOT: .note.gnu.property +; OBJ-NOT: .note.gnu.property diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-7.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-7.ll new file mode 100644 index 000000000000..b663dafe44c3 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-7.ll @@ -0,0 +1,23 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - 2>&1 | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf -S | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + ret i32 0 +} + +define dso_local i32 @g() #1 { +entry: + ret i32 0 +} + +attributes #0 = { "sign-return-address"="non-leaf" } + +attributes #1 = { "branch-target-enforcement" } + +; No common attribute, no note section +; ASM: warning: not setting BTI in feature flags +; ASM-NOT: .note.gnu.property +; OBJ-NOT: .note.gnu.property diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-8.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-8.ll new file mode 100644 index 000000000000..1e9497bd8566 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/note-gnu-property-pac-bti-8.ll @@ -0,0 +1,21 @@ +; RUN: llc -mtriple=aarch64-linux %s -o - | \ +; RUN: FileCheck %s --check-prefix=ASM +; RUN: llc -mtriple=aarch64-linux %s -filetype=obj -o - | \ +; RUN: llvm-readelf --notes | FileCheck %s --check-prefix=OBJ + +define dso_local i32 @f() #0 { +entry: + %r = tail call i32 @g() + ret i32 %r +} + +declare dso_local i32 @g() + +attributes #0 = { "branch-target-enforcement" } + +; Declarations don't prevent setting BTI +; ASM: .word 3221225472 +; ASM-NEXT: .word 4 +; ASM-NEXT .word 1 + +; OBJ: Properties: aarch64 feature: BTI