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linux/include/asm-mips/uaccess.h
Ralf Baechle e03b526932 [MIPS] Fixup copy_from_user_inatomic 
From the 01408c4939 log message:

The problem is that when we write to a file, the copy from userspace to
pagecache is first done with preemption disabled, so if the source
address is not immediately available the copy fails *and* *zeros* *the*
*destination*.

This is a problem because a concurrent read (which admittedly is an odd
thing to do) might see zeros rather that was there before the write, or
what was there after, or some mixture of the two (any of these being a
reasonable thing to see).

If the copy did fail, it will immediately be retried with preemption
re-enabled so any transient problem with accessing the source won't
cause an error.

The first copying does not need to zero any uncopied bytes, and doing
so causes the problem.  It uses copy_from_user_atomic rather than
copy_from_user so the simple expedient is to change copy_from_user_atomic
to *not* zero out bytes on failure.

< --- end cite --- >

This patch finally implements at least a not so pretty solution by
duplicating the relevant part of __copy_user.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-20 01:26:42 +00:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000, 03, 04 by Ralf Baechle
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
*/
#ifndef _ASM_UACCESS_H
#define _ASM_UACCESS_H
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/thread_info.h>
#include <asm-generic/uaccess.h>
/*
* The fs value determines whether argument validity checking should be
* performed or not. If get_fs() == USER_DS, checking is performed, with
* get_fs() == KERNEL_DS, checking is bypassed.
*
* For historical reasons, these macros are grossly misnamed.
*/
#ifdef CONFIG_32BIT
#define __UA_LIMIT 0x80000000UL
#define __UA_ADDR ".word"
#define __UA_LA "la"
#define __UA_ADDU "addu"
#define __UA_t0 "$8"
#define __UA_t1 "$9"
#endif /* CONFIG_32BIT */
#ifdef CONFIG_64BIT
#define __UA_LIMIT (- TASK_SIZE)
#define __UA_ADDR ".dword"
#define __UA_LA "dla"
#define __UA_ADDU "daddu"
#define __UA_t0 "$12"
#define __UA_t1 "$13"
#endif /* CONFIG_64BIT */
/*
* USER_DS is a bitmask that has the bits set that may not be set in a valid
* userspace address. Note that we limit 32-bit userspace to 0x7fff8000 but
* the arithmetic we're doing only works if the limit is a power of two, so
* we use 0x80000000 here on 32-bit kernels. If a process passes an invalid
* address in this range it's the process's problem, not ours :-)
*/
#define KERNEL_DS ((mm_segment_t) { 0UL })
#define USER_DS ((mm_segment_t) { __UA_LIMIT })
#define VERIFY_READ 0
#define VERIFY_WRITE 1
#define get_ds() (KERNEL_DS)
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
#define segment_eq(a,b) ((a).seg == (b).seg)
/*
* Is a address valid? This does a straighforward calculation rather
* than tests.
*
* Address valid if:
* - "addr" doesn't have any high-bits set
* - AND "size" doesn't have any high-bits set
* - AND "addr+size" doesn't have any high-bits set
* - OR we are in kernel mode.
*
* __ua_size() is a trick to avoid runtime checking of positive constant
* sizes; for those we already know at compile time that the size is ok.
*/
#define __ua_size(size) \
((__builtin_constant_p(size) && (signed long) (size) > 0) ? 0 : (size))
/*
* access_ok: - Checks if a user space pointer is valid
* @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
* %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
* to write to a block, it is always safe to read from it.
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
* Context: User context only. This function may sleep.
*
* Checks if a pointer to a block of memory in user space is valid.
*
* Returns true (nonzero) if the memory block may be valid, false (zero)
* if it is definitely invalid.
*
* Note that, depending on architecture, this function probably just
* checks that the pointer is in the user space range - after calling
* this function, memory access functions may still return -EFAULT.
*/
#define __access_mask get_fs().seg
#define __access_ok(addr, size, mask) \
(((signed long)((mask) & ((addr) | ((addr) + (size)) | __ua_size(size)))) == 0)
#define access_ok(type, addr, size) \
likely(__access_ok((unsigned long)(addr), (size),__access_mask))
/*
* put_user: - Write a simple value into user space.
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
* Context: User context only. This function may sleep.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and @x must be assignable
* to the result of dereferencing @ptr.
*
* Returns zero on success, or -EFAULT on error.
*/
#define put_user(x,ptr) \
__put_user_check((x),(ptr),sizeof(*(ptr)))
/*
* get_user: - Get a simple variable from user space.
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
* Context: User context only. This function may sleep.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and the result of
* dereferencing @ptr must be assignable to @x without a cast.
*
* Returns zero on success, or -EFAULT on error.
* On error, the variable @x is set to zero.
*/
#define get_user(x,ptr) \
__get_user_check((x),(ptr),sizeof(*(ptr)))
/*
* __put_user: - Write a simple value into user space, with less checking.
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
* Context: User context only. This function may sleep.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and @x must be assignable
* to the result of dereferencing @ptr.
*
* Caller must check the pointer with access_ok() before calling this
* function.
*
* Returns zero on success, or -EFAULT on error.
*/
#define __put_user(x,ptr) \
__put_user_nocheck((x),(ptr),sizeof(*(ptr)))
/*
* __get_user: - Get a simple variable from user space, with less checking.
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
* Context: User context only. This function may sleep.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and the result of
* dereferencing @ptr must be assignable to @x without a cast.
*
* Caller must check the pointer with access_ok() before calling this
* function.
*
* Returns zero on success, or -EFAULT on error.
* On error, the variable @x is set to zero.
*/
#define __get_user(x,ptr) \
__get_user_nocheck((x),(ptr),sizeof(*(ptr)))
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))
/*
* Yuck. We need two variants, one for 64bit operation and one
* for 32 bit mode and old iron.
*/
#ifdef CONFIG_32BIT
#define __GET_USER_DW(val, ptr) __get_user_asm_ll32(val, ptr)
#endif
#ifdef CONFIG_64BIT
#define __GET_USER_DW(val, ptr) __get_user_asm(val, "ld", ptr)
#endif
extern void __get_user_unknown(void);
#define __get_user_common(val, size, ptr) \
do { \
switch (size) { \
case 1: __get_user_asm(val, "lb", ptr); break; \
case 2: __get_user_asm(val, "lh", ptr); break; \
case 4: __get_user_asm(val, "lw", ptr); break; \
case 8: __GET_USER_DW(val, ptr); break; \
default: __get_user_unknown(); break; \
} \
} while (0)
#define __get_user_nocheck(x,ptr,size) \
({ \
long __gu_err; \
\
__get_user_common((x), size, ptr); \
__gu_err; \
})
#define __get_user_check(x,ptr,size) \
({ \
long __gu_err = -EFAULT; \
const __typeof__(*(ptr)) __user * __gu_ptr = (ptr); \
\
if (likely(access_ok(VERIFY_READ, __gu_ptr, size))) \
__get_user_common((x), size, __gu_ptr); \
\
__gu_err; \
})
#define __get_user_asm(val, insn, addr) \
{ \
long __gu_tmp; \
\
__asm__ __volatile__( \
"1: " insn " %1, %3 \n" \
"2: \n" \
" .section .fixup,\"ax\" \n" \
"3: li %0, %4 \n" \
" j 2b \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" "__UA_ADDR "\t1b, 3b \n" \
" .previous \n" \
: "=r" (__gu_err), "=r" (__gu_tmp) \
: "0" (0), "o" (__m(addr)), "i" (-EFAULT)); \
\
(val) = (__typeof__(*(addr))) __gu_tmp; \
}
/*
* Get a long long 64 using 32 bit registers.
*/
#define __get_user_asm_ll32(val, addr) \
{ \
union { \
unsigned long long l; \
__typeof__(*(addr)) t; \
} __gu_tmp; \
\
__asm__ __volatile__( \
"1: lw %1, (%3) \n" \
"2: lw %D1, 4(%3) \n" \
"3: .section .fixup,\"ax\" \n" \
"4: li %0, %4 \n" \
" move %1, $0 \n" \
" move %D1, $0 \n" \
" j 3b \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" " __UA_ADDR " 1b, 4b \n" \
" " __UA_ADDR " 2b, 4b \n" \
" .previous \n" \
: "=r" (__gu_err), "=&r" (__gu_tmp.l) \
: "0" (0), "r" (addr), "i" (-EFAULT)); \
\
(val) = __gu_tmp.t; \
}
/*
* Yuck. We need two variants, one for 64bit operation and one
* for 32 bit mode and old iron.
*/
#ifdef CONFIG_32BIT
#define __PUT_USER_DW(ptr) __put_user_asm_ll32(ptr)
#endif
#ifdef CONFIG_64BIT
#define __PUT_USER_DW(ptr) __put_user_asm("sd", ptr)
#endif
#define __put_user_nocheck(x,ptr,size) \
({ \
__typeof__(*(ptr)) __pu_val; \
long __pu_err = 0; \
\
__pu_val = (x); \
switch (size) { \
case 1: __put_user_asm("sb", ptr); break; \
case 2: __put_user_asm("sh", ptr); break; \
case 4: __put_user_asm("sw", ptr); break; \
case 8: __PUT_USER_DW(ptr); break; \
default: __put_user_unknown(); break; \
} \
__pu_err; \
})
#define __put_user_check(x,ptr,size) \
({ \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
__typeof__(*(ptr)) __pu_val = (x); \
long __pu_err = -EFAULT; \
\
if (likely(access_ok(VERIFY_WRITE, __pu_addr, size))) { \
switch (size) { \
case 1: __put_user_asm("sb", __pu_addr); break; \
case 2: __put_user_asm("sh", __pu_addr); break; \
case 4: __put_user_asm("sw", __pu_addr); break; \
case 8: __PUT_USER_DW(__pu_addr); break; \
default: __put_user_unknown(); break; \
} \
} \
__pu_err; \
})
#define __put_user_asm(insn, ptr) \
{ \
__asm__ __volatile__( \
"1: " insn " %z2, %3 # __put_user_asm\n" \
"2: \n" \
" .section .fixup,\"ax\" \n" \
"3: li %0, %4 \n" \
" j 2b \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" " __UA_ADDR " 1b, 3b \n" \
" .previous \n" \
: "=r" (__pu_err) \
: "0" (0), "Jr" (__pu_val), "o" (__m(ptr)), \
"i" (-EFAULT)); \
}
#define __put_user_asm_ll32(ptr) \
{ \
__asm__ __volatile__( \
"1: sw %2, (%3) # __put_user_asm_ll32 \n" \
"2: sw %D2, 4(%3) \n" \
"3: \n" \
" .section .fixup,\"ax\" \n" \
"4: li %0, %4 \n" \
" j 3b \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" " __UA_ADDR " 1b, 4b \n" \
" " __UA_ADDR " 2b, 4b \n" \
" .previous" \
: "=r" (__pu_err) \
: "0" (0), "r" (__pu_val), "r" (ptr), \
"i" (-EFAULT)); \
}
extern void __put_user_unknown(void);
/*
* We're generating jump to subroutines which will be outside the range of
* jump instructions
*/
#ifdef MODULE
#define __MODULE_JAL(destination) \
".set\tnoat\n\t" \
__UA_LA "\t$1, " #destination "\n\t" \
"jalr\t$1\n\t" \
".set\tat\n\t"
#else
#define __MODULE_JAL(destination) \
"jal\t" #destination "\n\t"
#endif
extern size_t __copy_user(void *__to, const void *__from, size_t __n);
#define __invoke_copy_to_user(to,from,n) \
({ \
register void __user *__cu_to_r __asm__ ("$4"); \
register const void *__cu_from_r __asm__ ("$5"); \
register long __cu_len_r __asm__ ("$6"); \
\
__cu_to_r = (to); \
__cu_from_r = (from); \
__cu_len_r = (n); \
__asm__ __volatile__( \
__MODULE_JAL(__copy_user) \
: "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \
: \
: "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \
"memory"); \
__cu_len_r; \
})
/*
* __copy_to_user: - Copy a block of data into user space, with less checking.
* @to: Destination address, in user space.
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
* Context: User context only. This function may sleep.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
*
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*/
#define __copy_to_user(to,from,n) \
({ \
void __user *__cu_to; \
const void *__cu_from; \
long __cu_len; \
\
might_sleep(); \
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
__cu_len = __invoke_copy_to_user(__cu_to, __cu_from, __cu_len); \
__cu_len; \
})
#define __copy_to_user_inatomic(to,from,n) \
({ \
void __user *__cu_to; \
const void *__cu_from; \
long __cu_len; \
\
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
__cu_len = __invoke_copy_to_user(__cu_to, __cu_from, __cu_len); \
__cu_len; \
})
#define __copy_from_user_inatomic(to,from,n) \
({ \
void *__cu_to; \
const void __user *__cu_from; \
long __cu_len; \
\
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
__cu_len = __invoke_copy_from_user_inatomic(__cu_to, __cu_from, \
__cu_len); \
__cu_len; \
})
/*
* copy_to_user: - Copy a block of data into user space.
* @to: Destination address, in user space.
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
* Context: User context only. This function may sleep.
*
* Copy data from kernel space to user space.
*
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*/
#define copy_to_user(to,from,n) \
({ \
void __user *__cu_to; \
const void *__cu_from; \
long __cu_len; \
\
might_sleep(); \
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
if (access_ok(VERIFY_WRITE, __cu_to, __cu_len)) \
__cu_len = __invoke_copy_to_user(__cu_to, __cu_from, \
__cu_len); \
__cu_len; \
})
#define __invoke_copy_from_user(to,from,n) \
({ \
register void *__cu_to_r __asm__ ("$4"); \
register const void __user *__cu_from_r __asm__ ("$5"); \
register long __cu_len_r __asm__ ("$6"); \
\
__cu_to_r = (to); \
__cu_from_r = (from); \
__cu_len_r = (n); \
__asm__ __volatile__( \
".set\tnoreorder\n\t" \
__MODULE_JAL(__copy_user) \
".set\tnoat\n\t" \
__UA_ADDU "\t$1, %1, %2\n\t" \
".set\tat\n\t" \
".set\treorder" \
: "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \
: \
: "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \
"memory"); \
__cu_len_r; \
})
#define __invoke_copy_from_user_inatomic(to,from,n) \
({ \
register void *__cu_to_r __asm__ ("$4"); \
register const void __user *__cu_from_r __asm__ ("$5"); \
register long __cu_len_r __asm__ ("$6"); \
\
__cu_to_r = (to); \
__cu_from_r = (from); \
__cu_len_r = (n); \
__asm__ __volatile__( \
".set\tnoreorder\n\t" \
__MODULE_JAL(__copy_user_inatomic) \
".set\tnoat\n\t" \
__UA_ADDU "\t$1, %1, %2\n\t" \
".set\tat\n\t" \
".set\treorder" \
: "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \
: \
: "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \
"memory"); \
__cu_len_r; \
})
/*
* __copy_from_user: - Copy a block of data from user space, with less checking.
* @to: Destination address, in kernel space.
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
* Context: User context only. This function may sleep.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
*
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*
* If some data could not be copied, this function will pad the copied
* data to the requested size using zero bytes.
*/
#define __copy_from_user(to,from,n) \
({ \
void *__cu_to; \
const void __user *__cu_from; \
long __cu_len; \
\
might_sleep(); \
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
__cu_len = __invoke_copy_from_user(__cu_to, __cu_from, \
__cu_len); \
__cu_len; \
})
/*
* copy_from_user: - Copy a block of data from user space.
* @to: Destination address, in kernel space.
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
* Context: User context only. This function may sleep.
*
* Copy data from user space to kernel space.
*
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*
* If some data could not be copied, this function will pad the copied
* data to the requested size using zero bytes.
*/
#define copy_from_user(to,from,n) \
({ \
void *__cu_to; \
const void __user *__cu_from; \
long __cu_len; \
\
might_sleep(); \
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
if (access_ok(VERIFY_READ, __cu_from, __cu_len)) \
__cu_len = __invoke_copy_from_user(__cu_to, __cu_from, \
__cu_len); \
__cu_len; \
})
#define __copy_in_user(to, from, n) __copy_from_user(to, from, n)
#define copy_in_user(to,from,n) \
({ \
void __user *__cu_to; \
const void __user *__cu_from; \
long __cu_len; \
\
might_sleep(); \
__cu_to = (to); \
__cu_from = (from); \
__cu_len = (n); \
if (likely(access_ok(VERIFY_READ, __cu_from, __cu_len) && \
access_ok(VERIFY_WRITE, __cu_to, __cu_len))) \
__cu_len = __invoke_copy_from_user(__cu_to, __cu_from, \
__cu_len); \
__cu_len; \
})
/*
* __clear_user: - Zero a block of memory in user space, with less checking.
* @to: Destination address, in user space.
* @n: Number of bytes to zero.
*
* Zero a block of memory in user space. Caller must check
* the specified block with access_ok() before calling this function.
*
* Returns number of bytes that could not be cleared.
* On success, this will be zero.
*/
static inline __kernel_size_t
__clear_user(void __user *addr, __kernel_size_t size)
{
__kernel_size_t res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
"move\t$5, $0\n\t"
"move\t$6, %2\n\t"
__MODULE_JAL(__bzero)
"move\t%0, $6"
: "=r" (res)
: "r" (addr), "r" (size)
: "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
return res;
}
#define clear_user(addr,n) \
({ \
void __user * __cl_addr = (addr); \
unsigned long __cl_size = (n); \
if (__cl_size && access_ok(VERIFY_WRITE, \
((unsigned long)(__cl_addr)), __cl_size)) \
__cl_size = __clear_user(__cl_addr, __cl_size); \
__cl_size; \
})
/*
* __strncpy_from_user: - Copy a NUL terminated string from userspace, with less checking.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @src: Source address, in user space.
* @count: Maximum number of bytes to copy, including the trailing NUL.
*
* Copies a NUL-terminated string from userspace to kernel space.
* Caller must check the specified block with access_ok() before calling
* this function.
*
* On success, returns the length of the string (not including the trailing
* NUL).
*
* If access to userspace fails, returns -EFAULT (some data may have been
* copied).
*
* If @count is smaller than the length of the string, copies @count bytes
* and returns @count.
*/
static inline long
__strncpy_from_user(char *__to, const char __user *__from, long __len)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
"move\t$5, %2\n\t"
"move\t$6, %3\n\t"
__MODULE_JAL(__strncpy_from_user_nocheck_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (__to), "r" (__from), "r" (__len)
: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
return res;
}
/*
* strncpy_from_user: - Copy a NUL terminated string from userspace.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @src: Source address, in user space.
* @count: Maximum number of bytes to copy, including the trailing NUL.
*
* Copies a NUL-terminated string from userspace to kernel space.
*
* On success, returns the length of the string (not including the trailing
* NUL).
*
* If access to userspace fails, returns -EFAULT (some data may have been
* copied).
*
* If @count is smaller than the length of the string, copies @count bytes
* and returns @count.
*/
static inline long
strncpy_from_user(char *__to, const char __user *__from, long __len)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
"move\t$5, %2\n\t"
"move\t$6, %3\n\t"
__MODULE_JAL(__strncpy_from_user_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (__to), "r" (__from), "r" (__len)
: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
return res;
}
/* Returns: 0 if bad, string length+1 (memory size) of string if ok */
static inline long __strlen_user(const char __user *s)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
__MODULE_JAL(__strlen_user_nocheck_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (s)
: "$2", "$4", __UA_t0, "$31");
return res;
}
/*
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
* Context: User context only. This function may sleep.
*
* Get the size of a NUL-terminated string in user space.
*
* Returns the size of the string INCLUDING the terminating NUL.
* On exception, returns 0.
*
* If there is a limit on the length of a valid string, you may wish to
* consider using strnlen_user() instead.
*/
static inline long strlen_user(const char __user *s)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
__MODULE_JAL(__strlen_user_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (s)
: "$2", "$4", __UA_t0, "$31");
return res;
}
/* Returns: 0 if bad, string length+1 (memory size) of string if ok */
static inline long __strnlen_user(const char __user *s, long n)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
"move\t$5, %2\n\t"
__MODULE_JAL(__strnlen_user_nocheck_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (s), "r" (n)
: "$2", "$4", "$5", __UA_t0, "$31");
return res;
}
/*
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
* Context: User context only. This function may sleep.
*
* Get the size of a NUL-terminated string in user space.
*
* Returns the size of the string INCLUDING the terminating NUL.
* On exception, returns 0.
*
* If there is a limit on the length of a valid string, you may wish to
* consider using strnlen_user() instead.
*/
static inline long strnlen_user(const char __user *s, long n)
{
long res;
might_sleep();
__asm__ __volatile__(
"move\t$4, %1\n\t"
"move\t$5, %2\n\t"
__MODULE_JAL(__strnlen_user_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (s), "r" (n)
: "$2", "$4", "$5", __UA_t0, "$31");
return res;
}
struct exception_table_entry
{
unsigned long insn;
unsigned long nextinsn;
};
extern int fixup_exception(struct pt_regs *regs);
#endif /* _ASM_UACCESS_H */
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