linux-kernel - Re: [PATCH 2/3] arm64: kprobes: Let arch do_page_fault() fix up page fault in user handler

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Message-ID: <Y4jAsYZOFw6CtYDI@FVFF77S0Q05N>
Date:   Thu, 1 Dec 2022 14:56:49 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
        Kalesh Singh <kaleshsingh@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sandeepa Prabhu <sandeepa.s.prabhu@...il.com>
Subject: Re: [PATCH 2/3] arm64: kprobes: Let arch do_page_fault() fix up page
 fault in user handler

On Thu, Dec 01, 2022 at 11:39:11PM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> Since arm64's do_page_fault() can handle the page fault correctly
> than kprobe_fault_handler() according to the context, let it handle
> the page fault instead of simply call fixup_exception() in the
> kprobe_fault_handler().
> 
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Acked-by: Mark Rutland <mark.rutland@....com>

Mark.

> ---
>  arch/arm64/kernel/probes/kprobes.c |    8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index c9e4d0720285..d2ae37f89774 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -294,14 +294,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
>  		}
>  
>  		break;
> -	case KPROBE_HIT_ACTIVE:
> -	case KPROBE_HIT_SSDONE:
> -		/*
> -		 * In case the user-specified fault handler returned
> -		 * zero, try to fix up.
> -		 */
> -		if (fixup_exception(regs))
> -			return 1;
>  	}
>  	return 0;
>  }
>