[llvm] [PAC][llvm-readobj][AArch64][ELF] Support `GNU_PROPERTY_AARCH64_FEATURE_PAUTH` (PR #85231)

[Fangrui Song via llvm-commits]

================
@@ -1,98 +1,211 @@
 # RUN: rm -rf %t && split-file %s %t && cd %t
 
-# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu abi-tag.s       -o tag.o
-# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu abi-tag-short.s -o tag-short.o
-# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu abi-tag-long.s  -o tag-long.o
-
-# RUN: llvm-readelf --notes tag.o       | FileCheck --check-prefix NORMAL %s
-# RUN: llvm-readelf --notes tag-short.o | FileCheck --check-prefix SHORT  %s
-# RUN: llvm-readelf --notes tag-long.o  | FileCheck --check-prefix LONG   %s
-
-# NORMAL: AArch64 PAuth ABI tag: platform 0x2a, version 0x1
-# SHORT:  AArch64 PAuth ABI tag: <corrupted size: expected at least 16, got 12>
-# LONG:   AArch64 PAuth ABI tag: platform 0x2a, version 0x1, additional info 0xEFCDAB8967452301
-
-# RUN: llvm-readobj --notes tag.o       | FileCheck --check-prefix LLVM-NORMAL %s
-# RUN: llvm-readobj --notes tag-short.o | FileCheck --check-prefix LLVM-SHORT %s
-# RUN: llvm-readobj --notes tag-long.o  | FileCheck --check-prefix LLVM-LONG %s
-
-# LLVM-SHORT:      Notes [
-# LLVM-SHORT-NEXT:   NoteSection {
-# LLVM-SHORT-NEXT:     Name: .note.AARCH64-PAUTH-ABI-tag
-# LLVM-SHORT-NEXT:     Offset: 0x40
-# LLVM-SHORT-NEXT:     Size: 0x1C
-# LLVM-SHORT-NEXT:     Note {
-# LLVM-SHORT-NEXT:       Owner: ARM
-# LLVM-SHORT-NEXT:       Data size: 0xC
-# LLVM-SHORT-NEXT:       Type: NT_ARM_TYPE_PAUTH_ABI_TAG
-# LLVM-SHORT-NEXT:       Description data (
-# LLVM-SHORT-NEXT:         0000: 2A000000 00000000 01000000
-# LLVM-SHORT-NEXT:       )
-# LLVM-SHORT-NEXT:     }
-# LLVM-SHORT-NEXT:   }
-# LLVM-SHORT-NEXT: ]
-
-# LLVM-NORMAL:      Notes [
-# LLVM-NORMAL-NEXT:   NoteSection {
-# LLVM-NORMAL-NEXT:     Name: .note.AARCH64-PAUTH-ABI-tag
-# LLVM-NORMAL-NEXT:     Offset: 0x40
-# LLVM-NORMAL-NEXT:     Size: 0x20
-# LLVM-NORMAL-NEXT:     Note {
-# LLVM-NORMAL-NEXT:       Owner: ARM
-# LLVM-NORMAL-NEXT:       Data size: 0x10
-# LLVM-NORMAL-NEXT:       Type: NT_ARM_TYPE_PAUTH_ABI_TAG
-# LLVM-NORMAL-NEXT:       Platform: 42
-# LLVM-NORMAL-NEXT:       Version: 1
-# LLVM-NORMAL-NEXT:     }
-# LLVM-NORMAL-NEXT:   }
-# LLVM-NORMAL-NEXT: ]
-
-# LLVM-LONG:      Notes [
-# LLVM-LONG-NEXT:   NoteSection {
-# LLVM-LONG-NEXT:     Name: .note.AARCH64-PAUTH-ABI-tag
-# LLVM-LONG-NEXT:     Offset: 0x40
-# LLVM-LONG-NEXT:     Size: 0x28
-# LLVM-LONG-NEXT:     Note {
-# LLVM-LONG-NEXT:       Owner: ARM
-# LLVM-LONG-NEXT:       Data size: 0x18
-# LLVM-LONG-NEXT:       Type: NT_ARM_TYPE_PAUTH_ABI_TAG
-# LLVM-LONG-NEXT:       Platform: 42
-# LLVM-LONG-NEXT:       Version: 1
-# LLVM-LONG-NEXT:       Additional info: EFCDAB8967452301
-# LLVM-LONG-NEXT:     }
-# LLVM-LONG-NEXT:   }
-# LLVM-LONG-NEXT: ]
-
-#--- abi-tag.s
-
-.section ".note.AARCH64-PAUTH-ABI-tag", "a"
-.long 4
-.long 16
-.long 1
-.asciz "ARM"
-
-.quad 42         // platform
-.quad 1          // version
-
-#--- abi-tag-short.s
-
-.section ".note.AARCH64-PAUTH-ABI-tag", "a"
-.long 4
-.long 12
-.long 1
-.asciz "ARM"
-
-.quad 42
-.word 1
-
-#--- abi-tag-long.s
-
-.section ".note.AARCH64-PAUTH-ABI-tag", "a"
-.long 4
-.long 24
-.long 1
-.asciz "ARM"
-
-.quad 42         // platform
-.quad 1          // version
-.quad 0x0123456789ABCDEF // extra data
+#--- gnu-42-1.s
+
+.section ".note.gnu.property", "a"
+  .long 4           /* Name length is always 4 ("GNU") */
----------------
MaskRay wrote:

`//` is shorter and more common since `//` is supported by all targets in GNU as.

https://github.com/llvm/llvm-project/pull/85231