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-rw-r--r--arch/arm64/lib/copy_from_user.S66
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diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_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 from user space to a kernel buffer (alignment handled by the hardware)
+ *
+ * Parameters:
+ * x0 - to
+ * x1 - from
+ * x2 - n
+ * Returns:
+ * x0 - bytes not copied
+ */
+ENTRY(__copy_from_user)
+ add x4, x1, x2 // upper user buffer boundary
+ subs x2, x2, #8
+ b.mi 2f
+1:
+USER(9f, ldr x3, [x1], #8 )
+ subs x2, x2, #8
+ 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
+ str w3, [x0], #4
+3: adds x2, x2, #2
+ b.mi 4f
+USER(9f, ldrh w3, [x1], #2 )
+ sub x2, x2, #2
+ strh w3, [x0], #2
+4: adds x2, x2, #1
+ b.mi 5f
+USER(9f, ldrb w3, [x1] )
+ strb w3, [x0]
+5: mov x0, #0
+ ret
+ENDPROC(__copy_from_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: sub x2, x4, x1
+ mov x3, x2
+10: strb wzr, [x0], #1 // zero remaining buffer space
+ subs x3, x3, #1
+ b.ne 10b
+ mov x0, x2 // bytes not copied
+ ret
+ .previous