From: Rolf Eike Beer <eike@sf-mail.de>
To: linux-parisc@vger.kernel.org
Subject: Re: [PATCH] parisc: Simplify and speed up get_user() and put_user()
Date: Mon, 11 Apr 2016 08:16:21 +0200 [thread overview]
Message-ID: <4798044.iQpCdZPV03@caliban.sf-tec.de> (raw)
In-Reply-To: <20160409062614.GA4203@ls3530.box>
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Am Samstag, 9. April 2016, 08:26:14 schrieb Helge Deller:
> This patch simplifies the code for get_user() and put_user() a lot.
>
> Instead of accessing kernel memory (%sr0) and userspace memory (%sr3)
> hard-coded in the assembler instruction, we now preload %sr2 with either
> %sr0 (for accessing KERNEL_DS) or with sr3 (to access USER_DS) and
> use %sr2 in the load directly.
>
> The generated code avoids a branch and speeds up execution by generating
> less assembler instructions.
I have put this on my C3600 (Linux 4.5.0, 32 bit kernel) and I see no negative
effects.
Eike
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next prev parent reply other threads:[~2016-04-11 6:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-09 6:26 [PATCH] parisc: Simplify and speed up get_user() and put_user() Helge Deller
2016-04-11 6:16 ` Rolf Eike Beer [this message]
2016-04-11 7:38 ` Rolf Eike Beer
2016-04-11 17:26 ` Rolf Eike Beer
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