linux-kernel - Re: [RFC][PATCH 06/22] x86,entry

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Date:   Thu, 4 Nov 2021 13:39:33 -0700
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, mark.rutland@....com,
        dvyukov@...gle.com, seanjc@...gle.com, pbonzini@...hat.com,
        mbenes@...e.cz
Subject: Re: [RFC][PATCH 06/22] x86,entry_32: Remove .fixup usage

On Thu, Nov 04, 2021 at 05:47:35PM +0100, Peter Zijlstra wrote:
> +++ b/arch/x86/include/asm/extable_fixup_types.h
> @@ -19,4 +19,6 @@
>  #define	EX_TYPE_DEFAULT_MCE_SAFE	12
>  #define	EX_TYPE_FAULT_MCE_SAFE		13
>  
> +#define EX_TYPE_POP_SEG			14
> +

This looks funky in the patch (but not in the editor), those other ones
have a tab after '#define'.

>  #endif
> --- a/arch/x86/mm/extable.c
> +++ b/arch/x86/mm/extable.c
> @@ -99,6 +99,13 @@ static bool ex_handler_clear_fs(const st
>  	return ex_handler_default(fixup, regs);
>  }
>  
> +static bool ex_handler_pop_seg(const struct exception_table_entry *fixup,
> +			       struct pt_regs *regs)
> +{
> +	*((unsigned int *)regs->sp) = 0;
> +	return ex_handler_default(fixup, regs);
> +}

Clever.  Should be "unsigned long" in case this ever gets used by
64-bit?  Also, I'd suggest a short comment.

-- 
Josh