From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [RFC PATCH for 4.18 09/16] powerpc: Add syscall detection for
 restartable sequences
Date: Tue, 5 Jun 2018 08:50:10 -0400 (EDT)
Message-ID: <1448764618.5559.1528203010706.JavaMail.zimbra@efficios.com>
References: <20180602124408.8430-1-mathieu.desnoyers@efficios.com> <20180602124408.8430-10-mathieu.desnoyers@efficios.com> <871sdlbyg7.fsf@concordia.ellerman.id.au>
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To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Boqun Feng <boqun.feng@gmail.com>, Andy Lutomirski <luto@amacapital.net>, Dave Watson <davejwatson@fb.com>, linux-kernel <linux-kernel@vger.kernel.org>, linux-api <linux-api@vger.kernel.org>, Paul Turner <pjt@google.com>, Andrew Morton <akpm@linux-foundation.org>, Russell King <linux@arm.linux.org.uk>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Andrew Hunter <ahh@google.com>, Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>, Ben Maurer <bmaurer@fb.com>, rostedt <rostedt@goodmis.org>, Josh Triplett <josh@joshtriplett.org>, Linus Torvalds <torvalds@linux-foundation.org>, Catalin Marinas <cata>
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----- On Jun 5, 2018, at 1:21 AM, Michael Ellerman mpe@ellerman.id.au wrote:

> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:
>> From: Boqun Feng <boqun.feng@gmail.com>
>>
>> Syscalls are not allowed inside restartable sequences, so add a call to
>> rseq_syscall() at the very beginning of system call exiting path for
>> CONFIG_DEBUG_RSEQ=y kernel. This could help us to detect whether there
>> is a syscall issued inside restartable sequences.
>>
>> [ Tested on 64-bit powerpc kernel by Mathieu Desnoyers. Still needs to
>>   be tested on 32-bit powerpc kernel. ]
>>
>> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
>> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> CC: Paul Mackerras <paulus@samba.org>
>> CC: Michael Ellerman <mpe@ellerman.id.au>
>> CC: Peter Zijlstra <peterz@infradead.org>
>> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>> CC: linuxppc-dev@lists.ozlabs.org
>> ---
>>  arch/powerpc/kernel/entry_32.S | 7 +++++++
>>  arch/powerpc/kernel/entry_64.S | 8 ++++++++
>>  2 files changed, 15 insertions(+)
> 
> I don't _love_ the #ifdefs in here, but they look correct and there's
> not really a better option until we rewrite the syscall handler in C.
> 
> The rseq selftests passed for me with this applied and enabled. So if
> you like here's some tags:
> 
> Tested-by: Michael Ellerman <mpe@ellerman.id.au>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
> 

Adding you ack to the series.

Thanks!

Mathieu

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