From: yu liu <yu....@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....@freescale.com>
Signed-off-by: Scott Wood <scottw...@freescale.com>
---
v3: no change

still waiting for Kumar's ack

 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(-)

diff --git a/arch/powerpc/kernel/head_fsl_booke.S 
b/arch/powerpc/kernel/head_fsl_booke.S
index 3e02710..b84fc5e 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 bd74fac..0ed23d1 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;
-- 
1.7.1


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