/*
* 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.
* Copyright (C) 2007 Maciej W. Rozycki
*/
#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
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
#define DADDI_SCRATCH "$0"
#else
#define DADDI_SCRATCH "$3"
#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", \
DADDI_SCRATCH, "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; \
})
extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n);
#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", \
DADDI_SCRATCH, "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", \
DADDI_SCRATCH, "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 */