From: David Laight <david.laight.linux@gmail.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-sound@vger.kernel.org,
Herve Codina <herve.codina@bootlin.com>,
Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH] ALSA: pcm: Convert multiple {get/put}_user to user_access_begin/user_access_end()
Date: Tue, 10 Jun 2025 20:53:58 +0100 [thread overview]
Message-ID: <20250610205358.07b1cc05@pumpkin> (raw)
In-Reply-To: <bf9288392b1d4b9e92fe29212d9cb933c5b3fbae.1749296015.git.christophe.leroy@csgroup.eu>
On Sat, 7 Jun 2025 13:37:42 +0200
Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
> With user access protection (Called SMAP on x86 or KUAP on powerpc)
> each and every call to get_user() or put_user() performs heavy
> operations to unlock and lock kernel access to userspace.
>
> To avoid that, perform user accesses by blocks using
> user_access_begin/user_access_end() and unsafe_get_user()/
> unsafe_put_user() and alike.
Did you consider using masked_user_access_begin() ?
It removes a conditional branch and lfence as well.
David
next prev parent reply other threads:[~2025-06-10 22:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-07 11:37 [PATCH] ALSA: pcm: Convert multiple {get/put}_user to user_access_begin/user_access_end() Christophe Leroy
2025-06-07 13:57 ` kernel test robot
2025-06-10 19:53 ` David Laight [this message]
2025-06-11 13:48 ` Christophe Leroy
2025-06-11 21:37 ` David Laight
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