[PATCH v3 09/21] powerpc/8xx: Optimize verification in FixupDAR

[Christophe Leroy]

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@xxxxxx>

---
Changes in v2:
- None

Changes in v3:
- None

 arch/powerpc/kernel/head_8xx.S |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index e5a250c..5037420 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -542,10 +542,8 @@ 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? */
-- 
1.7.1

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