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-rw-r--r--kernel/arch/arm64/lib/copy_to_user.S61
1 files changed, 61 insertions, 0 deletions
diff --git a/kernel/arch/arm64/lib/copy_to_user.S b/kernel/arch/arm64/lib/copy_to_user.S
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+++ b/kernel/arch/arm64/lib/copy_to_user.S
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+/*
+ * 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