powerpc/8xx: Optimize verification in FixupDAR

By XORing the upper part of the instruction code, we get a value that can
directly be verified with the second test and we can remove the first test.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 6f544eab983e..1bdd7c13ddc1 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -548,10 +548,8 @@ FixupDAR:/* Entry point for dcbx workaround. */
 /* Check if it really is a dcbx instruction. */
 /* dcbt and dcbtst does not generate DTLB Misses/Errors,
  * no need to include them here */
-        srwi    r10, r11, 26    /* check if major OP code is 31 */
-        cmpwi   cr0, r10, 31
-        bne-    141f
-        rlwinm  r10, r11, 0, 21, 30
+        xoris   r10, r11, 0x7c00        /* check if major OP code is 31 */
+        rlwinm  r10, r10, 0, 21, 5
         cmpwi   cr0, r10, 2028  /* Is dcbz? */
         beq+    142f
         cmpwi   cr0, r10, 940   /* Is dcbi? */