From 8c56cc8be5b38e3684eba96dc9b3f7ca7e495755 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 6 Jul 2012 15:45:39 +0100 Subject: [PATCH] ARM: 7449/1: use generic strnlen_user and strncpy_from_user functions This patch implements the word-at-a-time interface for ARM using the same algorithm as x86. We use the fls macro from ARMv5 onwards, where we have a clz instruction available which saves us a mov instruction when targetting Thumb-2. For older CPUs, we use the magic 0x0ff0001 constant. 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. Reviewed-by: Nicolas Pitre Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/Kconfig | 2 + arch/arm/include/asm/uaccess.h | 27 +++---------- arch/arm/include/asm/word-at-a-time.h | 55 +++++++++++++++++++++++++++ arch/arm/kernel/armksyms.c | 4 -- arch/arm/lib/Makefile | 1 - arch/arm/lib/strncpy_from_user.S | 43 --------------------- arch/arm/lib/strnlen_user.S | 40 ------------------- 7 files changed, 63 insertions(+), 109 deletions(-) create mode 100644 arch/arm/include/asm/word-at-a-time.h delete mode 100644 arch/arm/lib/strncpy_from_user.S delete mode 100644 arch/arm/lib/strnlen_user.S diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8c9d264f2108..574561a66d75 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -46,6 +46,8 @@ config ARM select GENERIC_SMP_IDLE_THREAD select KTIME_SCALAR select GENERIC_CLOCKEVENTS_BROADCAST if SMP + select GENERIC_STRNCPY_FROM_USER + select GENERIC_STRNLEN_USER help The ARM series is a line of low-power-consumption RISC chip designs licensed by ARM Ltd and targeted at embedded applications and diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 71f6536d17ac..479a6352e0b5 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -189,6 +189,9 @@ static inline void set_fs(mm_segment_t fs) #define access_ok(type,addr,size) (__range_ok(addr,size) == 0) +#define user_addr_max() \ + (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL) + /* * The "__xxx" versions of the user access functions do not verify the * address space - it must have been done previously with a separate @@ -398,9 +401,6 @@ extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned l #define __clear_user(addr,n) (memset((void __force *)addr, 0, n), 0) #endif -extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count); -extern unsigned long __must_check __strnlen_user(const char __user *s, long n); - static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { if (access_ok(VERIFY_READ, from, n)) @@ -427,24 +427,9 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo return n; } -static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count) -{ - long res = -EFAULT; - if (access_ok(VERIFY_READ, src, 1)) - res = __strncpy_from_user(dst, src, count); - return res; -} - -#define strlen_user(s) strnlen_user(s, ~0UL >> 1) +extern long strncpy_from_user(char *dest, const char __user *src, long count); -static inline long __must_check strnlen_user(const char __user *s, long n) -{ - unsigned long res = 0; - - if (__addr_ok(s)) - res = __strnlen_user(s, n); - - return res; -} +extern __must_check long strlen_user(const char __user *str); +extern __must_check long strnlen_user(const char __user *str, long n); #endif /* _ASMARM_UACCESS_H */ diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h new file mode 100644 index 000000000000..74b2d4578577 --- /dev/null +++ b/arch/arm/include/asm/word-at-a-time.h @@ -0,0 +1,55 @@ +#ifndef __ASM_ARM_WORD_AT_A_TIME_H +#define __ASM_ARM_WORD_AT_A_TIME_H + +#ifndef __ARMEB__ + +/* + * Little-endian word-at-a-time zero byte handling. + * Heavily based on the x86 algorithm. + */ +#include + +struct word_at_a_time { + const unsigned long one_bits, high_bits; +}; + +#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } + +static inline unsigned long has_zero(unsigned long a, unsigned long *bits, + const struct word_at_a_time *c) +{ + unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; + *bits = mask; + return mask; +} + +#define prep_zero_mask(a, bits, c) (bits) + +static inline unsigned long create_zero_mask(unsigned long bits) +{ + bits = (bits - 1) & ~bits; + return bits >> 7; +} + +static inline unsigned long find_zero(unsigned long mask) +{ + unsigned long ret; + +#if __LINUX_ARM_ARCH__ >= 5 + /* We have clz available. */ + ret = fls(mask) >> 3; +#else + /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ + ret = (0x0ff0001 + mask) >> 23; + /* Fix the 1 for 00 case */ + ret &= mask; +#endif + + return ret; +} + +#else /* __ARMEB__ */ +#include +#endif + +#endif /* __ASM_ARM_WORD_AT_A_TIME_H */ diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c index b57c75e0b01f..c3dff6abc89d 100644 --- a/arch/arm/kernel/armksyms.c +++ b/arch/arm/kernel/armksyms.c @@ -87,10 +87,6 @@ EXPORT_SYMBOL(memmove); EXPORT_SYMBOL(memchr); EXPORT_SYMBOL(__memzero); - /* user mem (segment) */ -EXPORT_SYMBOL(__strnlen_user); -EXPORT_SYMBOL(__strncpy_from_user); - #ifdef CONFIG_MMU EXPORT_SYMBOL(copy_page); diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile index 992769ae2599..d5060dab6e52 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -8,7 +8,6 @@ lib-y := backtrace.o changebit.o csumipv6.o csumpartial.o \ csumpartialcopy.o csumpartialcopyuser.o clearbit.o \ delay.o findbit.o memchr.o memcpy.o \ memmove.o memset.o memzero.o setbit.o \ - strncpy_from_user.o strnlen_user.o \ strchr.o strrchr.o \ testchangebit.o testclearbit.o testsetbit.o \ ashldi3.o ashrdi3.o lshrdi3.o muldi3.o \ diff --git a/arch/arm/lib/strncpy_from_user.S b/arch/arm/lib/strncpy_from_user.S deleted file mode 100644 index f202d7bd1647..000000000000 --- a/arch/arm/lib/strncpy_from_user.S +++ /dev/null @@ -1,43 +0,0 @@ -/* - * linux/arch/arm/lib/strncpy_from_user.S - * - * Copyright (C) 1995-2000 Russell King - * - * 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. - */ -#include -#include -#include - - .text - .align 5 - -/* - * Copy a string from user space to kernel space. - * r0 = dst, r1 = src, r2 = 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 ip, r1 -1: subs r2, r2, #1 - ldrusr r3, r1, 1, pl - bmi 2f - strb r3, [r0], #1 - teq r3, #0 - bne 1b - sub r1, r1, #1 @ take NUL character out of count -2: sub r0, r1, ip - mov pc, lr -ENDPROC(__strncpy_from_user) - - .pushsection .fixup,"ax" - .align 0 -9001: mov r3, #0 - strb r3, [r0, #0] @ null terminate - mov r0, #-EFAULT - mov pc, lr - .popsection - diff --git a/arch/arm/lib/strnlen_user.S b/arch/arm/lib/strnlen_user.S deleted file mode 100644 index 0ecbb459c4f1..000000000000 --- a/arch/arm/lib/strnlen_user.S +++ /dev/null @@ -1,40 +0,0 @@ -/* - * linux/arch/arm/lib/strnlen_user.S - * - * Copyright (C) 1995-2000 Russell King - * - * 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. - */ -#include -#include -#include - - .text - .align 5 - -/* Prototype: unsigned long __strnlen_user(const char *str, long n) - * Purpose : get length of a string in user memory - * Params : str - address of string in user memory - * Returns : length of string *including terminator* - * or zero on exception, or n + 1 if too long - */ -ENTRY(__strnlen_user) - mov r2, r0 -1: - ldrusr r3, r0, 1 - teq r3, #0 - beq 2f - subs r1, r1, #1 - bne 1b - add r0, r0, #1 -2: sub r0, r0, r2 - mov pc, lr -ENDPROC(__strnlen_user) - - .pushsection .fixup,"ax" - .align 0 -9001: mov r0, #0 - mov pc, lr - .popsection -- 2.20.1