[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag #85236

kovdan01 · 2024-03-14T14:54:04Z

Depends on #87545

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.

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.

kovdan01 · 2024-03-14T15:35:05Z

Buildkite job expectedly fails since the PR depends on #85235 unmerged yet

llvmbot · 2024-03-19T21:34:05Z

@llvm/pr-subscribers-llvm-ir

@llvm/pr-subscribers-backend-aarch64

Author: Daniil Kovalev (kovdan01)

Changes

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.

Full diff: https://github.com/llvm/llvm-project/pull/85236.diff

4 Files Affected:

(modified) llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp (+14-3)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.cpp (+26-7)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64TargetStreamer.h (+2-1)
(added) llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll (+50)

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",@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}

DanielKristofKiss · 2024-03-19T21:43:56Z

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

+          M.getModuleFlag("aarch64-elf-pauthabi-version")))
+    PAuthABIVersion = PAV->getZExtValue();
+
+  if ((PAuthABIPlatform == uint64_t(-1)) != (PAuthABIVersion == uint64_t(-1)))


could this check be added to the verifier?

Thanks for suggestion, see ab89fdc

DanielKristofKiss · 2024-03-21T08:41:29Z

llvm/lib/IR/Verifier.cpp

+  }
+
+  if ((PAuthABIPlatform == uint64_t(-1)) != (PAuthABIVersion == uint64_t(-1)))
+    report_fatal_error(


Suggested change

report_fatal_error(

CheckFailed(

Fixed, thanks, see 2f6dc0a

DanielKristofKiss

Could you consider adding a test for the verifier?

- Use `CheckFailed` instead of `report_fatal_error` in verifier - Add tests for verifier

kovdan01 · 2024-03-22T07:22:00Z

Could you consider adding a test for the verifier?

@DanielKristofKiss Thanks for suggestion, see llvm/test/Verifier/module-flags-note-gnu-property-elf-pauthabi.ll added in 2f6dc0a

github-actions · 2024-03-22T07:22:48Z

✅ With the latest revision this PR passed the C/C++ code formatter.

kovdan01 · 2024-04-04T18:04:53Z

The buildkite failure is unrelated (tools/flang/unittests/Runtime/FlangRuntimeTests.exe fails on Windows), so merging

[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag

6182b04

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.

kovdan01 requested a review from asl March 14, 2024 14:58

kovdan01 mentioned this pull request Mar 14, 2024

[CodeGen][AArch64][FMV] PAC the stub_helper's frame on arm64e #84704

Open

kovdan01 requested review from DanielKristofKiss, john-brawn-arm and MaskRay March 19, 2024 21:31

kovdan01 marked this pull request as ready for review March 19, 2024 21:33

llvmbot added the backend:AArch64 label Mar 19, 2024

DanielKristofKiss reviewed Mar 19, 2024

View reviewed changes

kovdan01 added 3 commits March 20, 2024 10:26

Merge branch 'main' into pauth-gnuprop-mc

9241efc

Rename PAuth ABI tag to PAuth ABI core info (see llvm#85231)

6a0bec4

Move check of module flags to verifier

ab89fdc

llvmbot added the llvm:ir label Mar 20, 2024

kovdan01 requested a review from DanielKristofKiss March 20, 2024 08:20

DanielKristofKiss reviewed Mar 21, 2024

View reviewed changes

DanielKristofKiss approved these changes Mar 21, 2024

View reviewed changes

MaskRay approved these changes Mar 22, 2024

View reviewed changes

Address review comments

2f6dc0a

- Use `CheckFailed` instead of `report_fatal_error` in verifier - Add tests for verifier

kovdan01 requested a review from DanielKristofKiss March 22, 2024 07:22

kovdan01 added 2 commits March 22, 2024 10:57

Fix code formatting

d313921

Merge branch 'main' into pauth-gnuprop-mc

fae3521

kovdan01 merged commit d97d560 into llvm:main Apr 4, 2024
3 of 4 checks passed

asl assigned kovdan01 May 21, 2024

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[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag #85236

[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag #85236

kovdan01 commented Mar 14, 2024 •

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edited

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[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag #85236

[AArch64][PAC][MC][ELF] Support PAuth ABI compatibility tag #85236

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