[POWERPC] system call micro optimisation

In the syscall path we currently have:

       crclr   so
       mfcr    r9

If we shift the crclr up we can avoid a stall on some CPUs.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 19ad5c6b18185309492e30640d2927e7998a50d8..221062c960c99ae23578e8942ee668e9214d27f0 100644 (file)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -57,6 +57,7 @@ system_call_common:
        beq-    1f
        ld      r1,PACAKSAVE(r13)
 1:     std     r10,0(r1)
+       crclr   so
        std     r11,_NIP(r1)
        std     r12,_MSR(r1)
        std     r0,GPR0(r1)
@@ -75,7 +76,6 @@ system_call_common:
        std     r11,GPR11(r1)
        std     r11,GPR12(r1)
        std     r9,GPR13(r1)
-       crclr   so
        mfcr    r9
        mflr    r10
        li      r11,0xc01