linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: tomasz.figa@gmail.com (Tomasz Figa)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ (part1)
Date: Sat, 05 Jul 2014 03:06:39 +0200	[thread overview]
Message-ID: <53B74F9F.8030604@gmail.com> (raw)
In-Reply-To: <E1X20mL-00083I-Sv@rmk-PC.arm.linux.org.uk>

Hi Russell,

On 01.07.2014 18:19, Russell King wrote:
> ARMv6 and greater introduced a new instruction ("bx") which can be used
> to return from function calls.  Recent CPUs perform better when the
> "bx lr" instruction is used rather than the "mov pc, lr" instruction,
> and this sequence is strongly recommended to be used by the ARM
> architecture manual (section A.4.1.1).
> 
> We provide a new macro "ret" with all its variants for the condition
> code which will resolve to the appropriate instruction.
> 
> Rather than doing this piecemeal, and miss some instances, change all
> the "mov pc" instances to use the new macro, with the exception of
> the "movs" instruction and the kprobes code.  This allows us to detect
> the "mov pc, lr" case and fix it up - and also gives us the possibility
> of deploying this for other registers depending on the CPU selection.
> 
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Build- and boot-tested on mach-s3c64xx.

Tested-by: Tomasz Figa <tomasz.figa@gmail.com>

Best regards,
Tomasz

      parent reply	other threads:[~2014-07-05  1:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-01 16:19 [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ (part1) Russell King
2014-07-01 16:42 ` Måns Rullgård
2014-07-01 17:13   ` Russell King - ARM Linux
2014-07-01 17:24     ` Måns Rullgård
2014-07-01 17:35       ` Will Deacon
2014-07-01 20:04         ` Måns Rullgård
2014-07-02  3:17         ` Nicolas Pitre
2014-07-01 19:26 ` Stephen Warren
2014-07-01 22:42 ` Robert Jarzmik
2014-07-05  1:06 ` Tomasz Figa [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=53B74F9F.8030604@gmail.com \
    --to=tomasz.figa@gmail.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).