linux-kernel - Re: [RFC][PATCH 3/7] x86/debug: Move kprobe_debug_handler() into exc_debug

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Date:   Fri, 21 Aug 2020 22:54:01 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Kyle Huey <me@...ehuey.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Robert O'Callahan <rocallahan@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [RFC][PATCH 3/7] x86/debug: Move kprobe_debug_handler() into
 exc_debug_kernel()

On Thu, 20 Aug 2020 12:38:35 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

Looks good to me.

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

Thanks,

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/include/asm/kprobes.h |    4 ++++
>  arch/x86/kernel/traps.c        |   10 ++++------
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> --- a/arch/x86/include/asm/kprobes.h
> +++ b/arch/x86/include/asm/kprobes.h
> @@ -106,5 +106,9 @@ extern int kprobe_exceptions_notify(stru
>  extern int kprobe_int3_handler(struct pt_regs *regs);
>  extern int kprobe_debug_handler(struct pt_regs *regs);
>  
> +#else
> +
> +static inline int kprobe_debug_handler(struct pt_regs *regs) { return 0; }
> +
>  #endif /* CONFIG_KPROBES */
>  #endif /* _ASM_X86_KPROBES_H */
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -806,12 +806,6 @@ static void handle_debug(struct pt_regs
>  	/* Store the virtualized DR6 value */
>  	tsk->thread.debugreg6 = dr6;
>  
> -#ifdef CONFIG_KPROBES
> -	if (kprobe_debug_handler(regs)) {
> -		return;
> -	}
> -#endif
> -
>  	if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0,
>  		       SIGTRAP) == NOTIFY_STOP) {
>  		return;
> @@ -877,8 +871,12 @@ static __always_inline void exc_debug_ke
>  	if ((dr6 & DR_STEP) && is_sysenter_singlestep(regs))
>  		dr6 &= ~DR_STEP;
>  
> +	if (kprobe_debug_handler(regs))
> +		goto out;
> +
>  	handle_debug(regs, dr6, false);
>  
> +out:
>  	instrumentation_end();
>  	idtentry_exit_nmi(regs, irq_state);
>  
> 
> 


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