[PATCH] XOR implementation for ARMv8

On Tue, Jun 30, 2015 at 05:01:17PM +0100, Will Deacon wrote:

On Wed, Jun 24, 2015 at 08:00:30AM +0100, ??? wrote:

quoted

diff -pruN -X dontdiff linux-4.0.5-orig/arch/arm64/lib/xor.S linux-4.0.5-mod/arch/arm64/lib/xor.S

--- linux-4.0.5-orig/arch/arm64/lib/xor.S       1970-01-01 08:00:00.000000000 +0800
+++ linux-4.0.5-mod/arch/arm64/lib/xor.S        2015-06-24 09:25:49.969256540 +0800

@@ -0,0 +1,228 @@
+/*
+ * arch/arm64/lib/xor.S
+ *
+ * Copyright (C) Xiaodong Liu <liuxiaodong@nudt.edu.cn>, Changsha, P.R. China
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+.macro xor_vectorregs16
+    eor v24.16b, v24.16b, v16.16b
+    eor v25.16b, v25.16b, v17.16b
+    eor v26.16b, v26.16b, v18.16b
+    eor v27.16b, v27.16b, v19.16b
+    eor v28.16b, v28.16b, v20.16b
+    eor v29.16b, v29.16b, v21.16b
+    eor v30.16b, v30.16b, v22.16b
+    eor v31.16b, v31.16b, v23.16b
+.endm
+
+.align 4
+
+/*
+ * void xor_arm64ldpregs16_2(unsigned long size, unsigned long * dst, unsigned long *src);
+ *
+ * Parameters:
+ *     x0 - size
+ *     x1 - dst
+ *     x2 - src
+ */
+ENTRY(xor_arm64ldpregs16_2)
+
+    lsr x0, x0, #10
+
+.p2align 4
+Loop23:
+    ldp q16, q17, [x2], #32
+    ldp q18, q19, [x2], #32
+    ldp q20, q21, [x2], #32
+    ldp q22, q23, [x2], #32

Have you tried using immediate offsets instead of post-index addressing?
E.g.

	ldp q16, q17, [x2]
	ldp q18, q19, [x2, #32], #32
	ldp q20, q21, [x2, #64], #32

Without the post-index offsets, of course ;)

Will