Patchwork [01/13] powerpc/e500: Save SPEFCSR in flush_spe_to_thread()

login
register
mail settings
Submitter Scott Wood
Date May 17, 2011, 11:35 p.m.
Message ID <20110517233551.GA3511@schlenkerla.am.freescale.net>
Download mbox | patch
Permalink /patch/96082/
State Accepted
Delegated to: Kumar Gala
Headers show

Comments

Scott Wood - May 17, 2011, 11:35 p.m.
From: yu liu <yu.liu@freescale.com>

giveup_spe() saves the SPE state which is protected by MSR[SPE].
However, modifying SPEFSCR does not trap when MSR[SPE]=0.
And since SPEFSCR is already saved/restored in _switch(),
not all the callers want to save SPEFSCR again.
Thus, saving SPEFSCR should not belong to giveup_spe().

This patch moves SPEFSCR saving to flush_spe_to_thread(),
and cleans up the caller that needs to save SPEFSCR accordingly.

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
---
This is a resending of http://patchwork.ozlabs.org/patch/88677/

Kumar, please ack to go via kvm.  This is holding up the rest of the SPE
patches, which in turn are holding up the MMU patches due to both
touching the MSR update code.

 arch/powerpc/kernel/head_fsl_booke.S |    2 --
 arch/powerpc/kernel/process.c        |    1 +
 arch/powerpc/kernel/traps.c          |    5 +----
 3 files changed, 2 insertions(+), 6 deletions(-)
Kumar Gala - May 19, 2011, 6:04 a.m.
On May 17, 2011, at 6:35 PM, Scott Wood wrote:

> From: yu liu <yu.liu@freescale.com>
> 
> giveup_spe() saves the SPE state which is protected by MSR[SPE].
> However, modifying SPEFSCR does not trap when MSR[SPE]=0.
> And since SPEFSCR is already saved/restored in _switch(),
> not all the callers want to save SPEFSCR again.
> Thus, saving SPEFSCR should not belong to giveup_spe().
> 
> This patch moves SPEFSCR saving to flush_spe_to_thread(),
> and cleans up the caller that needs to save SPEFSCR accordingly.
> 
> Signed-off-by: Liu Yu <yu.liu@freescale.com>
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> ---
> This is a resending of http://patchwork.ozlabs.org/patch/88677/
> 
> Kumar, please ack to go via kvm.  This is holding up the rest of the SPE
> patches, which in turn are holding up the MMU patches due to both
> touching the MSR update code.
> 
> arch/powerpc/kernel/head_fsl_booke.S |    2 --
> arch/powerpc/kernel/process.c        |    1 +
> arch/powerpc/kernel/traps.c          |    5 +----
> 3 files changed, 2 insertions(+), 6 deletions(-)

Acked-by: Kumar Gala <galak@kernel.crashing.org>

[ Alex, let me know if you want this via my powerpc.git tree or your kvm tree ]

- k
Alexander Graf - May 19, 2011, 9:38 a.m.
On 05/19/2011 08:04 AM, Kumar Gala wrote:
> On May 17, 2011, at 6:35 PM, Scott Wood wrote:
>
>> From: yu liu<yu.liu@freescale.com>
>>
>> giveup_spe() saves the SPE state which is protected by MSR[SPE].
>> However, modifying SPEFSCR does not trap when MSR[SPE]=0.
>> And since SPEFSCR is already saved/restored in _switch(),
>> not all the callers want to save SPEFSCR again.
>> Thus, saving SPEFSCR should not belong to giveup_spe().
>>
>> This patch moves SPEFSCR saving to flush_spe_to_thread(),
>> and cleans up the caller that needs to save SPEFSCR accordingly.
>>
>> Signed-off-by: Liu Yu<yu.liu@freescale.com>
>> Signed-off-by: Scott Wood<scottwood@freescale.com>
>> ---
>> This is a resending of http://patchwork.ozlabs.org/patch/88677/
>>
>> Kumar, please ack to go via kvm.  This is holding up the rest of the SPE
>> patches, which in turn are holding up the MMU patches due to both
>> touching the MSR update code.
>>
>> arch/powerpc/kernel/head_fsl_booke.S |    2 --
>> arch/powerpc/kernel/process.c        |    1 +
>> arch/powerpc/kernel/traps.c          |    5 +----
>> 3 files changed, 2 insertions(+), 6 deletions(-)
> Acked-by: Kumar Gala<galak@kernel.crashing.org>
>
> [ Alex, let me know if you want this via my powerpc.git tree or your kvm tree ]

I'll take them :). Thanks!

Alex

Patch

diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 5ecf54c..aede4f8 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -792,8 +792,6 @@  _GLOBAL(giveup_spe)
 	evmwumiaa evr6, evr6, evr6	/* evr6 <- ACC = 0 * 0 + ACC */
 	li	r4,THREAD_ACC
 	evstddx	evr6, r4, r3		/* save off accumulator */
-	mfspr	r6,SPRN_SPEFSCR
-	stw	r6,THREAD_SPEFSCR(r3)	/* save spefscr register value */
 	beq	1f
 	lwz	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 	lis	r3,MSR_SPE@h
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f74f355..138e7dd 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -213,6 +213,7 @@  void flush_spe_to_thread(struct task_struct *tsk)
 #ifdef CONFIG_SMP
 			BUG_ON(tsk != current);
 #endif
+			tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
 			giveup_spe(tsk);
 		}
 		preempt_enable();
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 5ddb801..742a0fb 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1356,10 +1356,7 @@  void SPEFloatingPointException(struct pt_regs *regs)
 	int code = 0;
 	int err;
 
-	preempt_disable();
-	if (regs->msr & MSR_SPE)
-		giveup_spe(current);
-	preempt_enable();
+	flush_spe_to_thread(current);
 
 	spefscr = current->thread.spefscr;
 	fpexc_mode = current->thread.fpexc_mode;