[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[Tony Lindgren]

Do not call test_for_ipi or test_for_ltrirq on UP systems.

Note that we can't put test_for_ltriq into SMP statement as
it's inlined into the code and the remaining lines of the
macro would still run before UP macro line.

Signed-off-by: Tony Lindgren <tony@atomide.com>
---
 arch/arm/kernel/entry-armv.S |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index bb2ef60..b8c1ec7 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -40,6 +40,11 @@
 	bne	asm_do_IRQ
 
 #ifdef CONFIG_SMP
+#ifdef CONFIG_SMP_ON_UP
+	adr	lr, BSYM(2f)	@ set lr to end of macro for early return
+	SMP(nop)		@ continue on SMP hardware
+	UP(mov	pc, lr)		@ return early on UP
+#endif
 	/*
 	 * XXX
 	 *
@@ -57,6 +62,7 @@
 	adrne	lr, BSYM(1b)
 	bne	do_local_timer
 #endif
+2:
 #endif
 
 	.endm
-- 
1.7.1

[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[Tony Lindgren]

[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[Shilimkar, Santosh]

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org [mailto:linux-omap-
> owner at vger.kernel.org] On Behalf Of Tony Lindgren
> Sent: Thursday, September 02, 2010 9:51 PM
> To: Russell King - ARM Linux
> Cc: linux-omap at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> Bryan Wu; Will Deacon
> Subject: [PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on
> UP systems
> 
> From f80d3cc85327ba84748646bb44a0c45103ef66bc Mon Sep 17 00:00:00 2001
> From: Tony Lindgren <tony@atomide.com>
> Date: Wed, 1 Sep 2010 20:40:47 -0700
> Subject: [PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on
> UP systems
> 
> Do not call test_for_ipi or test_for_ltrirq on UP systems.
> 
> Note that we can't put test_for_ltriq into SMP statement as
> it's inlined into the code and the remaining lines of the
> macro would still run before UP macro line.
> 
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  arch/arm/kernel/entry-armv.S |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
> index bb2ef60..b8c1ec7 100644
> --- a/arch/arm/kernel/entry-armv.S
> +++ b/arch/arm/kernel/entry-armv.S
> @@ -40,6 +40,11 @@
>  	bne	asm_do_IRQ
> 
>  #ifdef CONFIG_SMP
Do we need this code to be under " CONFIG_SMP" now ?
> +#ifdef CONFIG_SMP_ON_UP
> +	adr	lr, BSYM(2f)	@ set lr to end of macro for early return
> +	SMP(nop)		@ continue on SMP hardware
> +	UP(mov	pc, lr)		@ return early on UP
> +#endif
>  	/*
>  	 * XXX
>  	 *
> @@ -57,6 +62,7 @@
>  	adrne	lr, BSYM(1b)
>  	bne	do_local_timer
>  #endif
> +2:
>  #endif
> 
>  	.endm
> --
> 1.7.1
> 
> --
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[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[Russell King - ARM Linux]

On Thu, Sep 02, 2010 at 09:21:24AM -0700, Tony Lindgren wrote:
> Do not call test_for_ipi or test_for_ltrirq on UP systems.
> 
> Note that we can't put test_for_ltriq into SMP statement as
> it's inlined into the code and the remaining lines of the
> macro would still run before UP macro line.

I think we can do better than this - unfortunately the assembler gets
a little difficult (complaining about symbols in different sections),
but it's relatively easy to work-around by precomputing the offset
using .equ.  I'm debating about making this a UP_B(label) and hiding
these details beneath this macro, rather than having this kind of thing
exposed every time we need to do something like this.

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index bb2ef60..947b3ab 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -46,7 +46,9 @@
 	 * this macro assumes that irqstat (r6) and base (r5) are
 	 * preserved from get_irqnr_and_base above
 	 */
-	test_for_ipi r0, r6, r5, lr
+	SMP(test_for_ipi r0, r6, r5, lr)
+	.equ	off, 9997f - 9998b
+	UP(b	. + off)
 	movne	r0, sp
 	adrne	lr, BSYM(1b)
 	bne	do_IPI
@@ -57,6 +59,7 @@
 	adrne	lr, BSYM(1b)
 	bne	do_local_timer
 #endif
+9997:
 #endif
 
 	.endm

[PATCH 4/6] ARM: Do not call test_for_ipi or test_for_ltrirq on UP systems

[Russell King - ARM Linux]

On Fri, Sep 03, 2010 at 05:30:57PM +0530, Shilimkar, Santosh wrote:
> > diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
> > index bb2ef60..b8c1ec7 100644
> > --- a/arch/arm/kernel/entry-armv.S
> > +++ b/arch/arm/kernel/entry-armv.S
> > @@ -40,6 +40,11 @@
> >  	bne	asm_do_IRQ
> > 
> >  #ifdef CONFIG_SMP
> Do we need this code to be under " CONFIG_SMP" now ?

Yes, otherwise we get link errors for things like do_IPI and do_local_timer.