Re: [PATCH v2 02/11] unwind/x86: Add HAVE_USER_UNWIND

[Peter Zijlstra <peterz@infradead.org>]

On Sat, Sep 14, 2024 at 01:02:04AM +0200, Josh Poimboeuf wrote:
> Use ARCH_INIT_USER_FP_FRAME to describe how frame pointers are unwound
> on x86, and enable HAVE_USER_UNWIND accordinlgy so the user unwind
> interfaces can be used.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
>  arch/x86/Kconfig                   |  1 +
>  arch/x86/include/asm/user_unwind.h | 11 +++++++++++
>  2 files changed, 12 insertions(+)
>  create mode 100644 arch/x86/include/asm/user_unwind.h
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 007bab9f2a0e..266edff59058 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -286,6 +286,7 @@ config X86
>  	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
>  	select HAVE_UNSTABLE_SCHED_CLOCK
>  	select HAVE_USER_RETURN_NOTIFIER
> +	select HAVE_USER_UNWIND
>  	select HAVE_GENERIC_VDSO
>  	select VDSO_GETRANDOM			if X86_64
>  	select HOTPLUG_PARALLEL			if SMP && X86_64
> diff --git a/arch/x86/include/asm/user_unwind.h b/arch/x86/include/asm/user_unwind.h
> new file mode 100644
> index 000000000000..8c509c65cfb5
> --- /dev/null
> +++ b/arch/x86/include/asm/user_unwind.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_X86_USER_UNWIND_H
> +#define _ASM_X86_USER_UNWIND_H
> +
> +#define ARCH_INIT_USER_FP_FRAME							\
> +	.ra_off		= (s32)sizeof(long) * -1,				\
> +	.cfa_off	= (s32)sizeof(long) * 2,				\
> +	.fp_off		= (s32)sizeof(long) * -2,				\
> +	.use_fp		= true,

What about compat crap?