[llvm] [AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag (PR #85236)
Daniil Kovalev via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 14 07:54:10 PDT 2024
https://github.com/kovdan01 created https://github.com/llvm/llvm-project/pull/85236
Depends on #85235
Emit `GNU_PROPERTY_AARCH64_FEATURE_PAUTH` property in `.note.gnu.property` section depending on
`aarch64-elf-pauthabi-platform` and `aarch64-elf-pauthabi-version` llvm module flags.
>From 6182b040eeb66e2f413c7ae31bd895e3fbd02b71 Mon Sep 17 00:00:00 2001
From: Daniil Kovalev <dkovalev at accesssoftek.com>
Date: Wed, 13 Mar 2024 23:07:49 +0300
Subject: [PATCH] [AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag
Emit `GNU_PROPERTY_AARCH64_FEATURE_PAUTH` property in
`.note.gnu.property` section depending on
`aarch64-elf-pauthabi-platform` and `aarch64-elf-pauthabi-version` llvm
module flags.
---
llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp | 17 +++++--
.../MCTargetDesc/AArch64TargetStreamer.cpp | 33 +++++++++---
.../MCTargetDesc/AArch64TargetStreamer.h | 3 +-
.../AArch64/note-gnu-property-elf-pauthabi.ll | 50 +++++++++++++++++++
4 files changed, 92 insertions(+), 11 deletions(-)
create mode 100644 llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 4fa719ad67cf33..6f7d1548d09c76 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -268,13 +268,24 @@ void AArch64AsmPrinter::emitStartOfAsmFile(Module &M) {
if (Sign->getZExtValue())
Flags |= ELF::GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
- if (Flags == 0)
- return;
+ uint64_t PAuthABIPlatform = -1;
+ if (const auto *PAP = mdconst::extract_or_null<ConstantInt>(
+ M.getModuleFlag("aarch64-elf-pauthabi-platform")))
+ PAuthABIPlatform = PAP->getZExtValue();
+ uint64_t PAuthABIVersion = -1;
+ if (const auto *PAV = mdconst::extract_or_null<ConstantInt>(
+ M.getModuleFlag("aarch64-elf-pauthabi-version")))
+ PAuthABIVersion = PAV->getZExtValue();
+
+ if ((PAuthABIPlatform == uint64_t(-1)) != (PAuthABIVersion == uint64_t(-1)))
+ report_fatal_error(
+ "either both or no 'aarch64-elf-pauthabi-platform' and "
+ "'aarch64-elf-pauthabi-version' module flags must be present");
// Emit a .note.gnu.property section with the flags.
auto *TS =
static_cast<AArch64TargetStreamer *>(OutStreamer->getTargetStreamer());
- TS->emitNoteSection(Flags);
+ TS->emitNoteSection(Flags, PAuthABIPlatform, PAuthABIVersion);
}
void AArch64AsmPrinter::emitFunctionHeaderComment() {
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp
index e1d6dd7a056bce..dc5383ce941ed9 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp
@@ -58,8 +58,17 @@ void AArch64TargetStreamer::finish() {
emitNoteSection(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI);
}
-void AArch64TargetStreamer::emitNoteSection(unsigned Flags) {
- if (Flags == 0)
+void AArch64TargetStreamer::emitNoteSection(unsigned Flags,
+ uint64_t PAuthABIPlatform,
+ uint64_t PAuthABIVersion) {
+ assert((PAuthABIPlatform == uint64_t(-1)) ==
+ (PAuthABIVersion == uint64_t(-1)));
+ uint64_t DescSz = 0;
+ if (Flags != 0)
+ DescSz += 4 * 4;
+ if (PAuthABIPlatform != uint64_t(-1))
+ DescSz += 4 + 4 + 8 * 2;
+ if (DescSz == 0)
return;
MCStreamer &OutStreamer = getStreamer();
@@ -80,15 +89,25 @@ void AArch64TargetStreamer::emitNoteSection(unsigned Flags) {
// Emit the note header.
OutStreamer.emitValueToAlignment(Align(8));
OutStreamer.emitIntValue(4, 4); // data size for "GNU\0"
- OutStreamer.emitIntValue(4 * 4, 4); // Elf_Prop size
+ OutStreamer.emitIntValue(DescSz, 4); // Elf_Prop array 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
+ if (Flags != 0) {
+ 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
+ }
+
+ // Emit the PAuth ABI compatibility info
+ if (PAuthABIPlatform != uint64_t(-1)) {
+ OutStreamer.emitIntValue(ELF::GNU_PROPERTY_AARCH64_FEATURE_PAUTH, 4);
+ OutStreamer.emitIntValue(8 * 2, 4); // data size
+ OutStreamer.emitIntValue(PAuthABIPlatform, 8);
+ OutStreamer.emitIntValue(PAuthABIVersion, 8);
+ }
OutStreamer.endSection(Nt);
OutStreamer.switchSection(Cur);
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h
index 7676d88a82b5c7..e8a9dc445b96b1 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h
@@ -35,7 +35,8 @@ class AArch64TargetStreamer : public MCTargetStreamer {
void emitCurrentConstantPool();
/// Callback used to implement the .note.gnu.property section.
- void emitNoteSection(unsigned Flags);
+ void emitNoteSection(unsigned Flags, uint64_t PAuthABIPlatform = -1,
+ uint64_t PAuthABIVersion = -1);
/// Callback used to implement the .inst directive.
virtual void emitInst(uint32_t Inst);
diff --git a/llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll b/llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll
new file mode 100644
index 00000000000000..1eb6a2c7aceac3
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll
@@ -0,0 +1,50 @@
+; RUN: rm -rf %t && split-file %s %t && cd %t
+
+;--- ok.ll
+
+; RUN: llc -mtriple=aarch64-linux ok.ll -o - | \
+; RUN: FileCheck %s --check-prefix=ASM
+; RUN: llc -mtriple=aarch64-linux ok.ll -filetype=obj -o - | \
+; RUN: llvm-readelf --notes - | FileCheck %s --check-prefix=OBJ
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 1, !"aarch64-elf-pauthabi-platform", i32 268435458}
+!1 = !{i32 1, !"aarch64-elf-pauthabi-version", i32 85}
+
+; ASM: .section .note.gnu.property,"a", at note
+; ASM-NEXT: .p2align 3, 0x0
+; ASM-NEXT: .word 4
+; ASM-NEXT: .word 24
+; ASM-NEXT: .word 5
+; ASM-NEXT: .asciz "GNU"
+; 3221225473 = 0xc0000001 = GNU_PROPERTY_AARCH64_FEATURE_PAUTH
+; ASM-NEXT: .word 3221225473
+; ASM-NEXT: .word 16
+; ASM-NEXT: .xword 268435458
+; ASM-NEXT: .xword 85
+
+; OBJ: Displaying notes found in: .note.gnu.property
+; OBJ-NEXT: Owner Data size Description
+; OBJ-NEXT: GNU 0x00000018 NT_GNU_PROPERTY_TYPE_0 (property note)
+; OBJ-NEXT: AArch64 PAuth ABI tag: platform 0x10000002 (llvm_linux), version 0x55 (PointerAuthIntrinsics, !PointerAuthCalls, PointerAuthReturns, !PointerAuthAuthTraps, PointerAuthVTPtrAddressDiscrimination, !PointerAuthVTPtrTypeDiscrimination, PointerAuthInitFini)
+
+; ERR: either both or no 'aarch64-elf-pauthabi-platform' and 'aarch64-elf-pauthabi-version' module flags must be present
+
+;--- err1.ll
+
+; RUN: not --crash llc -mtriple=aarch64-linux err1.ll 2>&1 -o - | \
+; RUN: FileCheck %s --check-prefix=ERR
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"aarch64-elf-pauthabi-platform", i32 2}
+
+;--- err2.ll
+
+; RUN: not --crash llc -mtriple=aarch64-linux err2.ll 2>&1 -o - | \
+; RUN: FileCheck %s --check-prefix=ERR
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"aarch64-elf-pauthabi-version", i32 31}
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