From: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
To: Russell King <rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Cc: Andrew Lunn <andrew-g2DYL2Zd6BY@public.gmane.org>,
kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kevin Hilman
<khilman-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org>,
linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Thierry Reding
<thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org,
linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kukjin Kim <kgene.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
Herbert Xu
<herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org>,
Stefano Stabellini
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Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Gleb Natapov <gleb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
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xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org,
Sebastian Hesselbarth
<sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Jason Cooper <jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org>,
Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>,
Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>,
Hans Ulli Kroll
<ulli.kroll-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>,
Haoj
Subject: Re: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
Date: Wed, 2 Jul 2014 02:02:18 -0700 [thread overview]
Message-ID: <20140702090218.GV28884@atomide.com> (raw)
In-Reply-To: <E1X20Rs-00082S-KI-eh5Bv4kxaXIANfyc6IWni62ZND6+EDdj@public.gmane.org>
* Russell King <rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org> [140701 09:01]:
> 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-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Seems to boot fine for omaps:
Tested-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
next prev parent reply other threads:[~2014-07-02 9:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-01 15:58 [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ Russell King
2014-07-01 17:51 ` Andrew Lunn
2014-07-02 5:10 ` Shawn Guo
2014-07-02 9:24 ` Gregory CLEMENT
[not found] ` <E1X20Rs-00082S-KI-eh5Bv4kxaXIANfyc6IWni62ZND6+EDdj@public.gmane.org>
2014-07-02 9:02 ` Tony Lindgren [this message]
2014-07-02 11:31 ` Sekhar Nori
2014-07-04 11:09 ` Haojian Zhuang
2014-07-04 10:11 ` Christoffer Dall
2014-07-04 11:27 ` Stefano Stabellini
2014-07-04 14:24 ` Uwe Kleine-König
2014-07-07 9:21 ` Simon Horman
-- strict thread matches above, loose matches on Subject: below --
2014-07-01 16:14 Russell King
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