linux-kernel - Re: [patch V4 part 1 05/36] x86/entry: Flip _TIF_SIGPENDING and _TIF_NOTIFY

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Message-ID: <5eade6a3-06fc-d156-29cc-731be55eff3d@oracle.com>
Date:   Wed, 6 May 2020 15:06:32 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...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>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: Re: [patch V4 part 1 05/36] x86/entry: Flip _TIF_SIGPENDING and
 _TIF_NOTIFY_RESUME handling


On 5/5/20 3:16 PM, Thomas Gleixner wrote:
> Make sure task_work runs before any kind of userspace -- very much
> including signals -- is invoked.
> 
> Suggested-by: Andy Lutomirski <luto@...nel.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>   arch/x86/entry/common.c |    8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>

alex.

> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -156,16 +156,16 @@ static void exit_to_usermode_loop(struct
>   		if (cached_flags & _TIF_PATCH_PENDING)
>   			klp_update_patch_state(current);
>   
> -		/* deal with pending signal delivery */
> -		if (cached_flags & _TIF_SIGPENDING)
> -			do_signal(regs);
> -
>   		if (cached_flags & _TIF_NOTIFY_RESUME) {
>   			clear_thread_flag(TIF_NOTIFY_RESUME);
>   			tracehook_notify_resume(regs);
>   			rseq_handle_notify_resume(NULL, regs);
>   		}
>   
> +		/* deal with pending signal delivery */
> +		if (cached_flags & _TIF_SIGPENDING)
> +			do_signal(regs);
> +
>   		if (cached_flags & _TIF_USER_RETURN_NOTIFY)
>   			fire_user_return_notifiers();
>   
>