linux-kernel - Re: [PATCH 2/2] x86,kprobes: WARN if kprobes tries to handle a fault

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Date:   Tue, 25 May 2021 23:21:03 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        rostedt@...dmis.org, naveen.n.rao@...ux.vnet.ibm.com,
        ananth@...ux.ibm.com, x86@...nel.org
Subject: Re: [PATCH 2/2] x86,kprobes: WARN if kprobes tries to handle a
 fault

On Tue, 25 May 2021 09:25:20 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> With the removal of kprobe::handle_fault there is no reason left that
> kprobe_page_fault() would ever return true on x86, make sure it
> doesn't happen by accident.

OK, this is reasonable to me.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thank you!

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/mm/fault.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -1186,7 +1186,7 @@ do_kern_addr_fault(struct pt_regs *regs,
>  		return;
>  
>  	/* kprobes don't want to hook the spurious faults: */
> -	if (kprobe_page_fault(regs, X86_TRAP_PF))
> +	if (WARN_ON_ONCE(kprobe_page_fault(regs, X86_TRAP_PF)))
>  		return;
>  
>  	/*
> @@ -1239,7 +1239,7 @@ void do_user_addr_fault(struct pt_regs *
>  	}
>  
>  	/* kprobes don't want to hook the spurious faults: */
> -	if (unlikely(kprobe_page_fault(regs, X86_TRAP_PF)))
> +	if (WARN_ON_ONCE(kprobe_page_fault(regs, X86_TRAP_PF)))
>  		return;
>  
>  	/*
> 
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>