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authorCatalin Marinas <catalin.marinas@arm.com>2012-03-05 11:49:32 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2012-09-17 13:42:11 +0100
commit0aea86a2176c22647a5b683768f858d880d5e05b (patch)
tree6ffad0914ef41e69c672a0862f5a10a9e9f3cb43 /arch/arm64/lib/strncpy_from_user.S
parent2c020ed8d148f7562c01abaf875c9bbfb9a40a83 (diff)
downloadlinux-0aea86a2176c22647a5b683768f858d880d5e05b.tar.gz
arm64: User access library functions
This patch add support for various user access functions. These functions use the standard LDR/STR instructions and not the LDRT/STRT variants in order to allow kernel addresses (after set_fs(KERNEL_DS)). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/arm64/lib/strncpy_from_user.S')
-rw-r--r--arch/arm64/lib/strncpy_from_user.S50
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/arm64/lib/strncpy_from_user.S b/arch/arm64/lib/strncpy_from_user.S
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+++ b/arch/arm64/lib/strncpy_from_user.S
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+/*
+ * Based on arch/arm/lib/strncpy_from_user.S
+ *
+ * Copyright (C) 1995-2000 Russell King
+ * 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>
+#include <asm/errno.h>
+
+ .text
+ .align 5
+
+/*
+ * Copy a string from user space to kernel space.
+ * x0 = dst, x1 = src, x2 = byte length
+ * returns the number of characters copied (strlen of copied string),
+ * -EFAULT on exception, or "len" if we fill the whole buffer
+ */
+ENTRY(__strncpy_from_user)
+ mov x4, x1
+1: subs x2, x2, #1
+ bmi 2f
+USER(9f, ldrb w3, [x1], #1 )
+ strb w3, [x0], #1
+ cbnz w3, 1b
+ sub x1, x1, #1 // take NUL character out of count
+2: sub x0, x1, x4
+ ret
+ENDPROC(__strncpy_from_user)
+
+ .section .fixup,"ax"
+ .align 0
+9: strb wzr, [x0] // null terminate
+ mov x0, #-EFAULT
+ ret
+ .previous