@@ -441,26 +441,13 @@ _GLOBAL(_switch)
SAVE_8GPRS(14, r1)
SAVE_10GPRS(22, r1)
mflr r20 /* Return to switch caller */
- mfmsr r22
- li r0, MSR_FP
-#ifdef CONFIG_VSX
-BEGIN_FTR_SECTION
- oris r0,r0,MSR_VSX@h /* Disable VSX */
-END_FTR_SECTION_IFSET(CPU_FTR_VSX)
-#endif /* CONFIG_VSX */
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
- oris r0,r0,MSR_VEC@h /* Disable altivec */
mfspr r24,SPRN_VRSAVE /* save vrsave register value */
std r24,THREAD_VRSAVE(r3)
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
- and. r0,r0,r22
- beq+ 1f
- andc r22,r22,r0
- MTMSRD(r22)
- isync
-1: std r20,_NIP(r1)
+ std r20,_NIP(r1)
mfcr r23
std r23,_CCR(r1)
std r1,KSP(r3) /* Set old stack pointer */
There seems little point in disabling the FP/VMX/VSX MSR bits on context switch since we don't do it after calling enable_kernel_altivec() in other places. Writing the MSR is slow so lets not do it unnecessarily. A context switch microbenchmark using yield(): http://ozlabs.org/~anton/junkcode/context_switch2.c ./context_switch2 --type=yield --fp 0 0 shows an improvement of almost 3% on POWER8. Signed-off-by: Anton Blanchard <anton@samba.org> --- arch/powerpc/kernel/entry_64.S | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-)