arm64: klib: Optimised memory functions

This patch introduces AArch64-specific memory functions (memcpy,
memmove, memchr, memset). These functions are not optimised for any CPU
implementation but can be used as a starting point once hardware is
available.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/lib/memset.S

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2013 ARM Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Fill in the buffer with character c (alignment handled by the hardware)
+ *
+ * Parameters:
+ *	x0 - buf
+ *	x1 - c
+ *	x2 - n
+ * Returns:
+ *	x0 - buf
+ */
+ENTRY(memset)
+	mov	x4, x0
+	and	w1, w1, #0xff
+	orr	w1, w1, w1, lsl #8
+	orr	w1, w1, w1, lsl #16
+	orr	x1, x1, x1, lsl #32
+	subs	x2, x2, #8
+	b.mi	2f
+1:	str	x1, [x4], #8
+	subs	x2, x2, #8
+	b.pl	1b
+2:	adds	x2, x2, #4
+	b.mi	3f
+	sub	x2, x2, #4
+	str	w1, [x4], #4
+3:	adds	x2, x2, #2
+	b.mi	4f
+	sub	x2, x2, #2
+	strh	w1, [x4], #2
+4:	adds	x2, x2, #1
+	b.mi	5f
+	strb	w1, [x4]
+5:	ret
+ENDPROC(memset)