aboutsummaryrefslogtreecommitdiff
path: root/arch/arm64/lib/copy_in_user.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/lib/copy_in_user.S')
-rw-r--r--arch/arm64/lib/copy_in_user.S63
1 files changed, 63 insertions, 0 deletions
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
new file mode 100644
index 00000000000..84b6c9bb9b9
--- /dev/null
+++ b/arch/arm64/lib/copy_in_user.S
@@ -0,0 +1,63 @@
+/*
+ * Copy from user space to user space
+ *
+ * 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 from user space to user space (alignment handled by the hardware)
+ *
+ * Parameters:
+ * x0 - to
+ * x1 - from
+ * x2 - n
+ * Returns:
+ * x0 - bytes not copied
+ */
+ENTRY(__copy_in_user)
+ add x4, x0, x2 // upper user buffer boundary
+ subs x2, x2, #8
+ b.mi 2f
+1:
+USER(9f, 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
+USER(9f, ldr w3, [x1], #4 )
+ sub x2, x2, #4
+USER(9f, str w3, [x0], #4 )
+3: adds x2, x2, #2
+ b.mi 4f
+USER(9f, ldrh w3, [x1], #2 )
+ sub x2, x2, #2
+USER(9f, strh w3, [x0], #2 )
+4: adds x2, x2, #1
+ b.mi 5f
+USER(9f, ldrb w3, [x1] )
+USER(9f, strb w3, [x0] )
+5: mov x0, #0
+ ret
+ENDPROC(__copy_in_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: sub x0, x4, x0 // bytes not copied
+ ret
+ .previous