From: Shawn Guo <shawn.guo@freescale.com>
To: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Andrew Lunn <andrew@lunn.ch>,
kvm@vger.kernel.org, linux-sh@vger.kernel.org,
Kevin Hilman <khilman@deeprootsystems.com>,
Sekhar Nori <nsekhar@ti.com>,
linux-tegra@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
kvmarm@lists.cs.columbia.edu, linux-samsung-soc@vger.kernel.org,
Kukjin Kim <kgene.kim@samsung.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Magnus Damm <magnus.damm@gmail.com>,
Gleb Natapov <gleb@kernel.org>, Tony Lindgren <tony@atomide.com>,
xen-devel@lists.xenproject.org,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
Jason Cooper <jason@lakedaemon.net>,
Stephen Warren <swarren@wwwdotorg.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Hans Ulli Kroll <ulli.kroll@googlemail.com>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Simon Horman <horms@verge.net.au>,
Ben Dooks <ben-linux@fluff.org>,
Subject: Re: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
Date: Wed, 2 Jul 2014 13:10:27 +0800 [thread overview]
Message-ID: <20140702051026.GD16176@dragon> (raw)
In-Reply-To: <E1X20Rs-00082S-KI@rmk-PC.arm.linux.org.uk>
On Tue, Jul 01, 2014 at 04:58:24PM +0100, 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>
> ---
...
> arch/arm/mach-imx/suspend-imx6.S | 5 ++--
Tested-by: Shawn Guo <shawn.guo@freescale.com>
WARNING: multiple messages have this Message-ID (diff)
From: Shawn Guo <shawn.guo@freescale.com>
To: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Andrew Lunn <andrew@lunn.ch>,
kvm@vger.kernel.org, linux-sh@vger.kernel.org,
Kevin Hilman <khilman@deeprootsystems.com>,
Sekhar Nori <nsekhar@ti.com>,
linux-tegra@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
kvmarm@lists.cs.columbia.edu, linux-samsung-soc@vger.kernel.org,
Kukjin Kim <kgene.kim@samsung.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Magnus Damm <magnus.damm@gmail.com>,
Gleb Natapov <gleb@kernel.org>, Tony Lindgren <tony@atomide.com>,
xen-devel@lists.xenproject.org,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
Jason Cooper <jason@lakedaemon.net>,
Stephen Warren <swarren@wwwdotorg.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Hans Ulli Kroll <ulli.kroll@googlemail.com>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Simon Horman <horms@verge.net.au>,
Ben Dooks <ben-linux@fluff.org>
Subject: Re: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
Date: Wed, 2 Jul 2014 13:10:27 +0800 [thread overview]
Message-ID: <20140702051026.GD16176@dragon> (raw)
In-Reply-To: <E1X20Rs-00082S-KI@rmk-PC.arm.linux.org.uk>
On Tue, Jul 01, 2014 at 04:58:24PM +0100, 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>
> ---
...
> arch/arm/mach-imx/suspend-imx6.S | 5 ++--
Tested-by: Shawn Guo <shawn.guo@freescale.com>
WARNING: multiple messages have this Message-ID (diff)
From: shawn.guo@freescale.com (Shawn Guo)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
Date: Wed, 2 Jul 2014 13:10:27 +0800 [thread overview]
Message-ID: <20140702051026.GD16176@dragon> (raw)
In-Reply-To: <E1X20Rs-00082S-KI@rmk-PC.arm.linux.org.uk>
On Tue, Jul 01, 2014 at 04:58:24PM +0100, 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>
> ---
...
> arch/arm/mach-imx/suspend-imx6.S | 5 ++--
Tested-by: Shawn Guo <shawn.guo@freescale.com>
next prev parent reply other threads:[~2014-07-02 5:10 UTC|newest]
Thread overview: 46+ 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 15:58 ` Russell King
2014-07-01 17:51 ` Andrew Lunn
2014-07-01 17:51 ` Andrew Lunn
2014-07-01 17:51 ` Andrew Lunn
2014-07-01 17:51 ` Andrew Lunn
2014-07-02 5:10 ` Shawn Guo [this message]
2014-07-02 5:10 ` Shawn Guo
2014-07-02 5:10 ` Shawn Guo
2014-07-02 5:10 ` Shawn Guo
2014-07-02 9:02 ` Tony Lindgren
2014-07-02 9:24 ` Gregory CLEMENT
2014-07-02 9:24 ` Gregory CLEMENT
2014-07-02 9:24 ` Gregory CLEMENT
2014-07-02 9:24 ` Gregory CLEMENT
2014-07-02 11:31 ` Sekhar Nori
[not found] ` <E1X20Rs-00082S-KI-eh5Bv4kxaXIANfyc6IWni62ZND6+EDdj@public.gmane.org>
2014-07-02 9:02 ` Tony Lindgren
2014-07-02 9:02 ` Tony Lindgren
2014-07-02 9:02 ` Tony Lindgren
2014-07-02 11:31 ` Sekhar Nori
2014-07-02 11:31 ` Sekhar Nori
2014-07-02 11:31 ` Sekhar Nori
2014-07-04 11:09 ` Haojian Zhuang
2014-07-04 11:09 ` Haojian Zhuang
2014-07-04 11:09 ` Haojian Zhuang
2014-07-04 10:11 ` Christoffer Dall
2014-07-04 10:11 ` Christoffer Dall
2014-07-04 10:11 ` Christoffer Dall
2014-07-04 10:11 ` Christoffer Dall
2014-07-04 11:09 ` Haojian Zhuang
2014-07-04 11:27 ` Stefano Stabellini
2014-07-04 11:27 ` Stefano Stabellini
2014-07-04 11:27 ` Stefano Stabellini
2014-07-04 11:27 ` Stefano Stabellini
2014-07-04 14:24 ` Uwe Kleine-König
2014-07-04 14:24 ` Uwe Kleine-König
2014-07-04 14:24 ` Uwe Kleine-König
2014-07-04 14:24 ` Uwe Kleine-König
2014-07-07 9:21 ` Simon Horman
2014-07-07 9:21 ` Simon Horman
2014-07-07 9:21 ` Simon Horman
2014-07-07 9:21 ` Simon Horman
-- strict thread matches above, loose matches on Subject: below --
2014-07-01 16:14 Russell King
2014-07-01 16:14 Russell King
2014-07-01 16:14 ` Russell King
2014-07-01 15:58 Russell King
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