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arm64: use generic strnlen_user and strncpy_from_user functions
This patch implements the word-at-a-time interface for arm64 using the same algorithm as ARM. We use the fls64 macro, which expands to a clz instruction via a compiler builtin. Big-endian configurations make use of the implementation from asm-generic. With this implemented, we can replace our byte-at-a-time strnlen_user and strncpy_from_user functions with the optimised generic versions. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon
Catalin Marinas
parent
7158627686
commit
12a0ef7b0a
@ -17,6 +17,8 @@ config ARM64
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select GENERIC_IRQ_SHOW
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select GENERIC_SCHED_CLOCK
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_STRNCPY_FROM_USER
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select GENERIC_STRNLEN_USER
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select GENERIC_TIME_VSYSCALL
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select HARDIRQS_SW_RESEND
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select HAVE_ARCH_TRACEHOOK
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@ -100,6 +100,7 @@ static inline void set_fs(mm_segment_t fs)
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})
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#define access_ok(type, addr, size) __range_ok(addr, size)
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#define user_addr_max get_fs
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/*
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* The "__xxx" versions of the user access functions do not verify the address
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@ -240,9 +241,6 @@ extern unsigned long __must_check __copy_to_user(void __user *to, const void *fr
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extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
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extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
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extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
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extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
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static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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if (access_ok(VERIFY_READ, from, n))
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@ -276,24 +274,9 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
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return n;
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}
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static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
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{
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long res = -EFAULT;
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if (access_ok(VERIFY_READ, src, 1))
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res = __strncpy_from_user(dst, src, count);
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return res;
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}
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extern long strncpy_from_user(char *dest, const char __user *src, long count);
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#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
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static inline long __must_check strnlen_user(const char __user *s, long n)
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{
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unsigned long res = 0;
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if (__addr_ok(s))
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res = __strnlen_user(s, n);
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return res;
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}
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extern __must_check long strlen_user(const char __user *str);
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extern __must_check long strnlen_user(const char __user *str, long n);
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#endif /* __ASM_UACCESS_H */
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54
arch/arm64/include/asm/word-at-a-time.h
Normal file
54
arch/arm64/include/asm/word-at-a-time.h
Normal file
@ -0,0 +1,54 @@
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/*
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* Copyright (C) 2013 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_WORD_AT_A_TIME_H
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#define __ASM_WORD_AT_A_TIME_H
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#ifndef __AARCH64EB__
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#include <linux/kernel.h>
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struct word_at_a_time {
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const unsigned long one_bits, high_bits;
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};
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#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
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static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
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const struct word_at_a_time *c)
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{
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unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
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*bits = mask;
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return mask;
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}
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#define prep_zero_mask(a, bits, c) (bits)
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static inline unsigned long create_zero_mask(unsigned long bits)
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{
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bits = (bits - 1) & ~bits;
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return bits >> 7;
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}
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static inline unsigned long find_zero(unsigned long mask)
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{
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return fls64(mask) >> 3;
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}
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#else /* __AARCH64EB__ */
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#include <asm-generic/word-at-a-time.h>
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#endif
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#endif /* __ASM_WORD_AT_A_TIME_H */
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@ -29,13 +29,10 @@
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#include <asm/checksum.h>
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/* user mem (segment) */
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EXPORT_SYMBOL(__strnlen_user);
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EXPORT_SYMBOL(__strncpy_from_user);
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EXPORT_SYMBOL(copy_page);
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EXPORT_SYMBOL(clear_page);
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/* user mem (segment) */
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EXPORT_SYMBOL(__copy_from_user);
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EXPORT_SYMBOL(__copy_to_user);
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EXPORT_SYMBOL(__clear_user);
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@ -1,6 +1,4 @@
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lib-y := bitops.o delay.o \
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strncpy_from_user.o strnlen_user.o clear_user.o \
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copy_from_user.o copy_to_user.o copy_in_user.o \
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copy_page.o clear_page.o \
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memchr.o memcpy.o memmove.o memset.o \
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lib-y := bitops.o clear_user.o delay.o copy_from_user.o \
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copy_to_user.o copy_in_user.o copy_page.o \
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clear_page.o memchr.o memcpy.o memmove.o memset.o \
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strchr.o strrchr.o
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@ -1,50 +0,0 @@
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/*
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* Based on arch/arm/lib/strncpy_from_user.S
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*
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* Copyright (C) 1995-2000 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/errno.h>
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.text
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.align 5
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/*
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* Copy a string from user space to kernel space.
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* x0 = dst, x1 = src, x2 = byte length
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* returns the number of characters copied (strlen of copied string),
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* -EFAULT on exception, or "len" if we fill the whole buffer
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*/
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ENTRY(__strncpy_from_user)
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mov x4, x1
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1: subs x2, x2, #1
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bmi 2f
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USER(9f, ldrb w3, [x1], #1 )
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strb w3, [x0], #1
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cbnz w3, 1b
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sub x1, x1, #1 // take NUL character out of count
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2: sub x0, x1, x4
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ret
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ENDPROC(__strncpy_from_user)
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.section .fixup,"ax"
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.align 0
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9: strb wzr, [x0] // null terminate
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mov x0, #-EFAULT
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ret
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.previous
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@ -1,47 +0,0 @@
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/*
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* Based on arch/arm/lib/strnlen_user.S
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*
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* Copyright (C) 1995-2000 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/errno.h>
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.text
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.align 5
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/* Prototype: unsigned long __strnlen_user(const char *str, long n)
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* Purpose : get length of a string in user memory
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* Params : str - address of string in user memory
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* Returns : length of string *including terminator*
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* or zero on exception, or n if too long
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*/
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ENTRY(__strnlen_user)
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mov x2, x0
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1: subs x1, x1, #1
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b.mi 2f
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USER(9f, ldrb w3, [x0], #1 )
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cbnz w3, 1b
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2: sub x0, x0, x2
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ret
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ENDPROC(__strnlen_user)
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.section .fixup,"ax"
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.align 0
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9: mov x0, #0
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ret
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.previous
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