linux-kernel - Re: [RFC 2/4] Restartable sequences: powerpc architecture support

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Date:	Thu, 28 Jul 2016 03:13:07 +0000 (UTC)
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Boqun Feng <boqun.feng@...il.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-api <linux-api@...r.kernel.org>,
	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>, Paul Turner <pjt@...gle.com>,
	Andrew Hunter <ahh@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...capital.net>,
	Andi Kleen <andi@...stfloor.org>,
	Dave Watson <davejwatson@...com>, Chris Lameter <cl@...ux.com>,
	Ben Maurer <bmaurer@...com>, rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [RFC 2/4] Restartable sequences: powerpc architecture support

----- On Jul 27, 2016, at 11:05 AM, Boqun Feng boqun.feng@...il.com wrote:

> Call the rseq_handle_notify_resume() function on return to userspace if
> TIF_NOTIFY_RESUME thread flag is set.
> 
> Increment the event counter and perform fixup on the pre-signal when a
> signal is delivered on top of a restartable sequence critical section.

Picked into my patchset. I'm keeping a volatile branch of my current
work at https://github.com/compudj/linux-percpu-dev/tree/rseq-fallback
if you are interested in the progress.

Thanks!

Mathieu

> 
> Signed-off-by: Boqun Feng <boqun.feng@...il.com>
> ---
> arch/powerpc/Kconfig         | 1 +
> arch/powerpc/kernel/signal.c | 3 +++
> 2 files changed, 4 insertions(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 0a9d439bcda6..4e93629c6b84 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -120,6 +120,7 @@ config PPC
> 	select HAVE_PERF_USER_STACK_DUMP
> 	select HAVE_REGS_AND_STACK_ACCESS_API
> 	select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64
> +	select HAVE_RSEQ
> 	select ARCH_WANT_IPC_PARSE_VERSION
> 	select SPARSE_IRQ
> 	select IRQ_DOMAIN
> diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
> index cb64d6feb45a..339d0ebe2906 100644
> --- a/arch/powerpc/kernel/signal.c
> +++ b/arch/powerpc/kernel/signal.c
> @@ -131,6 +131,8 @@ static void do_signal(struct pt_regs *regs)
> 	/* Re-enable the breakpoints for the signal stack */
> 	thread_change_pc(current, regs);
> 
> +	rseq_signal_deliver(regs);
> +
> 	if (is32) {
>         	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
> 			ret = handle_rt_signal32(&ksig, oldset, regs);
> @@ -157,6 +159,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long
> thread_info_flags)
> 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
> 		clear_thread_flag(TIF_NOTIFY_RESUME);
> 		tracehook_notify_resume(regs);
> +		rseq_handle_notify_resume(regs);
> 	}
> 
> 	user_enter();
> --
> 2.9.0

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com