Re: [PATCH v3 02/19] x86/asm: Avoid emitting DWARF CFI for non-VDSO

[Jens Remus <jremus@linux.ibm.com>]

On 28.10.2024 22:47, Josh Poimboeuf wrote:
> VDSO is the only part of the "kernel" using DWARF CFI directives.  For
> the kernel proper, ensure the CFI_* macros don't do anything.
> 
> These macros aren't yet being used outside of VDSO, so there's no
> functional change.

...

> diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h
> index 430fca13bb56..b1aa3fcd5bca 100644
> --- a/arch/x86/include/asm/dwarf2.h
> +++ b/arch/x86/include/asm/dwarf2.h
...
> @@ -29,13 +39,24 @@
>   	 * useful to anyone.  Note we should not use this directive if we
>   	 * ever decide to enable DWARF unwinding at runtime.
>   	 */
> +
>   	.cfi_sections .debug_frame
> -#else
> -	 /*
> -	  * For the vDSO, emit both runtime unwind information and debug
> -	  * symbols for the .dbg file.
> -	  */
> -	.cfi_sections .eh_frame, .debug_frame
> -#endif
> +
> +#define CFI_STARTPROC
> +#define CFI_ENDPROC
> +#define CFI_DEF_CFA
> +#define CFI_DEF_CFA_REGISTER
> +#define CFI_DEF_CFA_OFFSET
> +#define CFI_ADJUST_CFA_OFFSET
> +#define CFI_OFFSET
> +#define CFI_REL_OFFSET
> +#define CFI_REGISTER
> +#define CFI_RESTORE
> +#define CFI_REMEMBER_STATE
> +#define CFI_RESTORE_STATE
> +#define CFI_UNDEFINED
> +#define CFI_ESCAPE

Don't all of the above need to be defined to "#", so that they change 
any parameters into an assembler comment? For example:

#define CFI_STARTPROC		#

> +
> +#endif /* !BUILD_VDSO */
>   
>   #endif /* _ASM_X86_DWARF2_H */

Thanks and regards,
Jens
-- 
Jens Remus
Linux on Z Development (D3303) and z/VSE Support
+49-7031-16-1128 Office
jremus@de.ibm.com

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