1 files changed, 61 insertions, 0 deletions

diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
new file mode 100644
index 000000000000..a0aeeb9b7a28
--- /dev/null
+++ b/arch/arm64/lib/copy_to_user.S
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 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>
+
+/*
+ * Copy to user space from a kernel buffer (alignment handled by the hardware)
+ *
+ * Parameters:
+ *      x0 - to
+ *      x1 - from
+ *      x2 - n
+ * Returns:
+ *      x0 - bytes not copied
+ */
+ENTRY(__copy_to_user)
+        add     x4, x0, x2                      // upper user buffer boundary
+        subs    x2, x2, #8
+        b.mi    2f
+1:
+        ldr     x3, [x1], #8
+        subs    x2, x2, #8
+USER(9f, str    x3, [x0], #8    )
+        b.pl    1b
+2:      adds    x2, x2, #4
+        b.mi    3f
+        ldr     w3, [x1], #4
+        sub     x2, x2, #4
+USER(9f, str    w3, [x0], #4    )
+3:      adds    x2, x2, #2
+        b.mi    4f
+        ldrh    w3, [x1], #2
+        sub     x2, x2, #2
+USER(9f, strh   w3, [x0], #2    )
+4:      adds    x2, x2, #1
+        b.mi    5f
+        ldrb    w3, [x1]
+USER(9f, strb   w3, [x0]        )
+5:      mov     x0, #0
+        ret
+ENDPROC(__copy_to_user)
+
+        .section .fixup,"ax"
+        .align  2
+9:      sub     x0, x4, x0                      // bytes not copied
+        ret
+        .previous