From: Jens Axboe <axboe@kernel.dk>
To: Max Filippov <jcmvbkbc@gmail.com>
Cc: "open list:TENSILICA XTENSA PORT (xtensa)"
<linux-xtensa@linux-xtensa.org>, Chris Zankel <chris@zankel.net>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] xtensa: fix broken TIF_NOTIFY_SIGNAL assembly
Date: Thu, 12 Nov 2020 08:45:01 -0700 [thread overview]
Message-ID: <7998b455-c7bd-5caf-d6a9-d1c0404f2b5f@kernel.dk> (raw)
In-Reply-To: <CAMo8BfL=3PEi3GWd6LR9kiKViN=t1KbgbkjEEwT8GAb-Uvnp0A@mail.gmail.com>
On 11/12/20 2:12 AM, Max Filippov wrote:
> On Wed, Nov 11, 2020 at 1:05 PM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> On 11/11/20 1:53 PM, Max Filippov wrote:
>>> TIF_NOTIFY_SIGNAL handling in xtensa assembly is implemented
>>> incorrectly: there should be a call to do_notify_resume when either
>>> TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_NOTIFY_SIGNAL bit is set in the
>>> thread_info::flags. The straightforward way to do it would be
>>>
>>> _bbsi.l a4, TIF_NEED_RESCHED, 3f
>>> _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
>>> _bbsi.l a4, TIF_NOTIFY_SIGNAL, 2f
>>> _bbci.l a4, TIF_SIGPENDING, 5f
>>>
>>> Optimize it a little bit and use bit mask and bnone opcode to skip
>>> do_notify_resume invocation. Shuffle _TIF_* flags a bit so that used bit
>>> mask fits into the immediate field of movi opcode.
>>
>> Thanks - do you mind if I fold this in with a reference to your
>> changes? Seems like that'd be a better option than leaving it
>> broken for a bit.
>
> Sure Jens, by all means!
Thanks! Done.
--
Jens Axboe
prev parent reply other threads:[~2020-11-12 15:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 20:53 Max Filippov
2020-11-11 21:05 ` Jens Axboe
2020-11-12 9:12 ` Max Filippov
2020-11-12 15:45 ` Jens Axboe [this message]
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