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x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16

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After commit:

  884961618e ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S")

building arch/x86/entry/vdso/vdso32/sigreturn.S with LLVM 15 fails with:

  <instantiation>:18:20: error: invalid register name
   .cfi_offset eflags, 64
                     ^
  arch/x86/entry/vdso/vdso32/sigreturn.S:33:2: note: while in macro instantiation
   STARTPROC_SIGNAL_FRAME 8
   ^

Support for eflags as an argument to .cfi_offset was added in the LLVM
16 development cycle:

    67bd3c58c0 [1]

Only add this .cfi_offset directive if it is supported by the assembler
to clear up the error.

[ mingo: Tidied up the changelog and the comment a bit ]

Fixes: 884961618e ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: https://patch.msgid.link/20260123-x86-vdso32-wa-llvm-15-cfi-offset-eflags-v1-1-0f412e3516a4@kernel.org
This commit is contained in:
Nathan Chancellor 2026-01-23 16:20:28 -07:00 • committed by Ingo Molnar
parent 436ee609df
commit 3e30278e0c
1 changed files with 10 additions and 0 deletions
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10
arch/x86/entry/vdso/vdso32/sigreturn.S
View file

@ -22,7 +22,17 @@
CFI_OFFSET cs, IA32_SIGCONTEXT_cs
CFI_OFFSET ss, IA32_SIGCONTEXT_ss
CFI_OFFSET ds, IA32_SIGCONTEXT_ds
/*
* .cfi_offset eflags requires LLVM 16 or newer:
*
* https://github.com/llvm/llvm-project/commit/67bd3c58c0c7389e39c5a2f4d3b1a30459ccf5b7
*
* Check for 16.0.1 to ensure the support is present, as 16.0.0 may be a
* prerelease version.
*/
#if defined(CONFIG_AS_IS_GNU) || (defined(CONFIG_AS_IS_LLVM) && CONFIG_AS_VERSION >= 160001)
CFI_OFFSET eflags, IA32_SIGCONTEXT_flags
#endif
.endm
.text