linux-kernel - Re: [PATCH 03/14] arm: Add restartable sequences support

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Date:   Wed, 16 May 2018 18:18:09 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, Andrew Hunter <ahh@...gle.com>,
        Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
        Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Joel Fernandes <joelaf@...gle.com>
Subject: Re: [PATCH 03/14] arm: Add restartable sequences support

On Mon, Apr 30, 2018 at 06:44:22PM -0400, Mathieu Desnoyers wrote:
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index a7f8e7f4b88f..4f5c386631d4 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -91,6 +91,7 @@ config ARM
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_RCU_TABLE_FREE if (SMP && ARM_LPAE)
>  	select HAVE_REGS_AND_STACK_ACCESS_API
> +	select HAVE_RSEQ
>  	select HAVE_SYSCALL_TRACEPOINTS
>  	select HAVE_UID16
>  	select HAVE_VIRT_CPU_ACCOUNTING_GEN
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> index bd8810d4acb3..5879ab3f53c1 100644
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -541,6 +541,12 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
>  	int ret;
>  
>  	/*
> +	 * Increment event counter and perform fixup for the pre-signal
> +	 * frame.
> +	 */
> +	rseq_signal_deliver(regs);
> +
> +	/*
>  	 * Set up the stack frame
>  	 */
>  	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
> @@ -660,6 +666,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
>  			} else {
>  				clear_thread_flag(TIF_NOTIFY_RESUME);
>  				tracehook_notify_resume(regs);
> +				rseq_handle_notify_resume(regs);
>  			}
>  		}
>  		local_irq_disable();

I think you forgot to hook up rseq_syscall() checking.