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uaccess.h

/* 
 * Authors:    Bjorn Wesen (bjornw@axis.com)
 *           Hans-Peter Nilsson (hp@axis.com)
 */

/* Asm:s have been tweaked (within the domain of correctness) to give
   satisfactory results for "gcc version 2.96 20000427 (experimental)".

   Check regularly...

   Register $r9 is chosen for temporaries, being a call-clobbered register
   first in line to be used (notably for local blocks), not colliding with
   parameter registers.  */

#ifndef _CRIS_UACCESS_H
#define _CRIS_UACCESS_H

#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/processor.h>
#include <asm/page.h>

#define VERIFY_READ     0
#define VERIFY_WRITE    1

/*
 * 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.
 */

#define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })

/* addr_limit is the maximum accessible address for the task. we misuse
 * the KERNEL_DS and USER_DS values to both assign and compare the 
 * addr_limit values through the equally misnamed get/set_fs macros.
 * (see above)
 */

#define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFF)
#define USER_DS         MAKE_MM_SEG(TASK_SIZE)

#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)

#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
#define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
#define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
#define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))

#include <arch/uaccess.h>

/*
 * The exception table consists of pairs of addresses: the first is the
 * address of an instruction that is allowed to fault, and the second is
 * the address at which the program should continue.  No registers are
 * modified, so it is entirely up to the continuation code to figure out
 * what to do.
 *
 * All the routines below use bits of fixup code that are out of line
 * with the main instruction path.  This means when everything is well,
 * we don't even have to jump over them.  Further, they do not intrude
 * on our cache or tlb entries.
 */

struct exception_table_entry
{
      unsigned long insn, fixup;
};

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 *
 * As we use the same address space for kernel and user data on
 * CRIS, we can just do these as direct assignments.  (Of course, the
 * exception handling means that it's no longer "just"...)
 */
#define get_user(x,ptr) \
  __get_user_check((x),(ptr),sizeof(*(ptr)))
#define put_user(x,ptr) \
  __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))

#define __get_user(x,ptr) \
  __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
#define __put_user(x,ptr) \
  __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))

extern long __put_user_bad(void);

#define __put_user_size(x,ptr,size,retval)                  \
do {                                            \
      retval = 0;                               \
      switch (size) {                                 \
        case 1: __put_user_asm(x,ptr,retval,"move.b"); break;     \
        case 2: __put_user_asm(x,ptr,retval,"move.w"); break;     \
        case 4: __put_user_asm(x,ptr,retval,"move.d"); break;     \
        case 8: __put_user_asm_64(x,ptr,retval); break;     \
        default: __put_user_bad();                    \
      }                                         \
} while (0)

#define __get_user_size(x,ptr,size,retval)                  \
do {                                            \
      retval = 0;                               \
      switch (size) {                                 \
        case 1: __get_user_asm(x,ptr,retval,"move.b"); break;     \
        case 2: __get_user_asm(x,ptr,retval,"move.w"); break;     \
        case 4: __get_user_asm(x,ptr,retval,"move.d"); break;     \
        case 8: __get_user_asm_64(x,ptr,retval); break;     \
        default: (x) = __get_user_bad();              \
      }                                         \
} while (0)

#define __put_user_nocheck(x,ptr,size)                \
({                                        \
      long __pu_err;                            \
      __put_user_size((x),(ptr),(size),__pu_err);     \
      __pu_err;                           \
})

#define __put_user_check(x,ptr,size)                        \
({                                              \
      long __pu_err = -EFAULT;                        \
      __typeof__(*(ptr)) *__pu_addr = (ptr);                \
      if (access_ok(VERIFY_WRITE,__pu_addr,size))           \
            __put_user_size((x),__pu_addr,(size),__pu_err); \
      __pu_err;                                 \
})

struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct *)(x))



#define __get_user_nocheck(x,ptr,size)                      \
({                                              \
      long __gu_err, __gu_val;                        \
      __get_user_size(__gu_val,(ptr),(size),__gu_err);      \
      (x) = (__typeof__(*(ptr)))__gu_val;             \
      __gu_err;                                 \
})

#define __get_user_check(x,ptr,size)                              \
({                                                    \
      long __gu_err = -EFAULT, __gu_val = 0;                      \
      const __typeof__(*(ptr)) *__gu_addr = (ptr);                \
      if (access_ok(VERIFY_READ,__gu_addr,size))                  \
            __get_user_size(__gu_val,__gu_addr,(size),__gu_err);  \
      (x) = (__typeof__(*(ptr)))__gu_val;                   \
      __gu_err;                                       \
})

extern long __get_user_bad(void);

/* More complex functions.  Most are inline, but some call functions that
   live in lib/usercopy.c  */

extern unsigned long __copy_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __copy_user_zeroing(void *to, const void __user *from, unsigned long n);
extern unsigned long __do_clear_user(void __user *to, unsigned long n);

static inline unsigned long
__generic_copy_to_user(void __user *to, const void *from, unsigned long n)
{
      if (access_ok(VERIFY_WRITE, to, n))
            return __copy_user(to,from,n);
      return n;
}

static inline unsigned long
__generic_copy_from_user(void *to, const void __user *from, unsigned long n)
{
      if (access_ok(VERIFY_READ, from, n))
            return __copy_user_zeroing(to,from,n);
      return n;
}

static inline unsigned long
__generic_clear_user(void __user *to, unsigned long n)
{
      if (access_ok(VERIFY_WRITE, to, n))
            return __do_clear_user(to,n);
      return n;
}

static inline long
__strncpy_from_user(char *dst, const char __user *src, long count)
{
      return __do_strncpy_from_user(dst, src, count);
}

static inline long
strncpy_from_user(char *dst, const char __user *src, long count)
{
      long res = -EFAULT;
      if (access_ok(VERIFY_READ, src, 1))
            res = __do_strncpy_from_user(dst, src, count);
      return res;
}


/* Note that these expand awfully if made into switch constructs, so
   don't do that.  */

static inline unsigned long
__constant_copy_from_user(void *to, const void __user *from, unsigned long n)
{
      unsigned long ret = 0;
      if (n == 0)
            ;
      else if (n == 1)
            __asm_copy_from_user_1(to, from, ret);
      else if (n == 2)
            __asm_copy_from_user_2(to, from, ret);
      else if (n == 3)
            __asm_copy_from_user_3(to, from, ret);
      else if (n == 4)
            __asm_copy_from_user_4(to, from, ret);
      else if (n == 5)
            __asm_copy_from_user_5(to, from, ret);
      else if (n == 6)
            __asm_copy_from_user_6(to, from, ret);
      else if (n == 7)
            __asm_copy_from_user_7(to, from, ret);
      else if (n == 8)
            __asm_copy_from_user_8(to, from, ret);
      else if (n == 9)
            __asm_copy_from_user_9(to, from, ret);
      else if (n == 10)
            __asm_copy_from_user_10(to, from, ret);
      else if (n == 11)
            __asm_copy_from_user_11(to, from, ret);
      else if (n == 12)
            __asm_copy_from_user_12(to, from, ret);
      else if (n == 13)
            __asm_copy_from_user_13(to, from, ret);
      else if (n == 14)
            __asm_copy_from_user_14(to, from, ret);
      else if (n == 15)
            __asm_copy_from_user_15(to, from, ret);
      else if (n == 16)
            __asm_copy_from_user_16(to, from, ret);
      else if (n == 20)
            __asm_copy_from_user_20(to, from, ret);
      else if (n == 24)
            __asm_copy_from_user_24(to, from, ret);
      else
            ret = __generic_copy_from_user(to, from, n);

      return ret;
}

/* Ditto, don't make a switch out of this.  */

static inline unsigned long
__constant_copy_to_user(void __user *to, const void *from, unsigned long n)
{
      unsigned long ret = 0;
      if (n == 0)
            ;
      else if (n == 1)
            __asm_copy_to_user_1(to, from, ret);
      else if (n == 2)
            __asm_copy_to_user_2(to, from, ret);
      else if (n == 3)
            __asm_copy_to_user_3(to, from, ret);
      else if (n == 4)
            __asm_copy_to_user_4(to, from, ret);
      else if (n == 5)
            __asm_copy_to_user_5(to, from, ret);
      else if (n == 6)
            __asm_copy_to_user_6(to, from, ret);
      else if (n == 7)
            __asm_copy_to_user_7(to, from, ret);
      else if (n == 8)
            __asm_copy_to_user_8(to, from, ret);
      else if (n == 9)
            __asm_copy_to_user_9(to, from, ret);
      else if (n == 10)
            __asm_copy_to_user_10(to, from, ret);
      else if (n == 11)
            __asm_copy_to_user_11(to, from, ret);
      else if (n == 12)
            __asm_copy_to_user_12(to, from, ret);
      else if (n == 13)
            __asm_copy_to_user_13(to, from, ret);
      else if (n == 14)
            __asm_copy_to_user_14(to, from, ret);
      else if (n == 15)
            __asm_copy_to_user_15(to, from, ret);
      else if (n == 16)
            __asm_copy_to_user_16(to, from, ret);
      else if (n == 20)
            __asm_copy_to_user_20(to, from, ret);
      else if (n == 24)
            __asm_copy_to_user_24(to, from, ret);
      else
            ret = __generic_copy_to_user(to, from, n);

      return ret;
}

/* No switch, please.  */

static inline unsigned long
__constant_clear_user(void __user *to, unsigned long n)
{
      unsigned long ret = 0;
      if (n == 0)
            ;
      else if (n == 1)
            __asm_clear_1(to, ret);
      else if (n == 2)
            __asm_clear_2(to, ret);
      else if (n == 3)
            __asm_clear_3(to, ret);
      else if (n == 4)
            __asm_clear_4(to, ret);
      else if (n == 8)
            __asm_clear_8(to, ret);
      else if (n == 12)
            __asm_clear_12(to, ret);
      else if (n == 16)
            __asm_clear_16(to, ret);
      else if (n == 20)
            __asm_clear_20(to, ret);
      else if (n == 24)
            __asm_clear_24(to, ret);
      else
            ret = __generic_clear_user(to, n);

      return ret;
}


#define clear_user(to, n)                 \
(__builtin_constant_p(n) ?                \
 __constant_clear_user(to, n) :                 \
 __generic_clear_user(to, n))

#define copy_from_user(to, from, n)       \
(__builtin_constant_p(n) ?                \
 __constant_copy_from_user(to, from, n) : \
 __generic_copy_from_user(to, from, n))

#define copy_to_user(to, from, n)         \
(__builtin_constant_p(n) ?                \
 __constant_copy_to_user(to, from, n) :         \
 __generic_copy_to_user(to, from, n))

/* We let the __ versions of copy_from/to_user inline, because they're often
 * used in fast paths and have only a small space overhead.
 */

static inline unsigned long
__generic_copy_from_user_nocheck(void *to, const void __user *from,
                         unsigned long n)
{
      return __copy_user_zeroing(to,from,n);
}

static inline unsigned long
__generic_copy_to_user_nocheck(void __user *to, const void *from,
                         unsigned long n)
{
      return __copy_user(to,from,n);
}

static inline unsigned long
__generic_clear_user_nocheck(void __user *to, unsigned long n)
{
      return __do_clear_user(to,n);
}

/* without checking */

#define __copy_to_user(to,from,n)   __generic_copy_to_user_nocheck((to),(from),(n))
#define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n))
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user
#define __clear_user(to,n) __generic_clear_user_nocheck((to),(n))

#define strlen_user(str)      strnlen_user((str), 0x7ffffffe)

#endif  /* __ASSEMBLY__ */

#endif      /* _CRIS_UACCESS_H */

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