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uaccess.h

/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * 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.
 */
#ifndef __ASM_AVR32_UACCESS_H
#define __ASM_AVR32_UACCESS_H

#include <linux/errno.h>
#include <linux/sched.h>

#define VERIFY_READ     0
#define VERIFY_WRITE    1

typedef struct {
      unsigned int is_user_space;
} mm_segment_t;

/*
 * 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 (Data Segment Register?), these macros are misnamed.
 */
#define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
#define segment_eq(a,b) ((a).is_user_space == (b).is_user_space)

#define USER_ADDR_LIMIT 0x80000000

#define KERNEL_DS MAKE_MM_SEG(0)
#define USER_DS         MAKE_MM_SEG(1)

#define get_ds()  (KERNEL_DS)

static inline mm_segment_t get_fs(void)
{
      return MAKE_MM_SEG(test_thread_flag(TIF_USERSPACE));
}

static inline void set_fs(mm_segment_t s)
{
      if (s.is_user_space)
            set_thread_flag(TIF_USERSPACE);
      else
            clear_thread_flag(TIF_USERSPACE);
}

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 *
 * We do the following checks:
 *   1. Is the access from kernel space?
 *   2. Does (addr + size) set the carry bit?
 *   3. Is (addr + size) a negative number (i.e. >= 0x80000000)?
 *
 * If yes on the first check, access is granted.
 * If no on any of the others, access is denied.
 */
#define __range_ok(addr, size)                                    \
      (test_thread_flag(TIF_USERSPACE)                      \
       && (((unsigned long)(addr) >= 0x80000000)                  \
           || ((unsigned long)(size) > 0x80000000)                \
           || (((unsigned long)(addr) + (unsigned long)(size)) > 0x80000000)))

#define access_ok(type, addr, size) (likely(__range_ok(addr, size) == 0))

/* Generic arbitrary sized copy. Return the number of bytes NOT copied */
extern __kernel_size_t __copy_user(void *to, const void *from,
                           __kernel_size_t n);

extern __kernel_size_t copy_to_user(void __user *to, const void *from,
                            __kernel_size_t n);
extern __kernel_size_t copy_from_user(void *to, const void __user *from,
                              __kernel_size_t n);

static inline __kernel_size_t __copy_to_user(void __user *to, const void *from,
                                   __kernel_size_t n)
{
      return __copy_user((void __force *)to, from, n);
}
static inline __kernel_size_t __copy_from_user(void *to,
                                     const void __user *from,
                                     __kernel_size_t n)
{
      return __copy_user(to, (const void __force *)from, n);
}

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

/*
 * 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)))

extern int __get_user_bad(void);
extern int __put_user_bad(void);

#define __get_user_nocheck(x, ptr, size)                    \
({                                                    \
      unsigned long __gu_val = 0;                           \
      int __gu_err = 0;                               \
                                                      \
      switch (size) {                                       \
      case 1: __get_user_asm("ub", __gu_val, ptr, __gu_err); break;     \
      case 2: __get_user_asm("uh", __gu_val, ptr, __gu_err); break;     \
      case 4: __get_user_asm("w", __gu_val, ptr, __gu_err); break;      \
      default: __gu_err = __get_user_bad(); break;                \
      }                                               \
                                                      \
      x = (typeof(*(ptr)))__gu_val;                         \
      __gu_err;                                       \
})

#define __get_user_check(x, ptr, size)                            \
({                                                    \
      unsigned long __gu_val = 0;                           \
      const typeof(*(ptr)) __user * __gu_addr = (ptr);            \
      int __gu_err = 0;                               \
                                                      \
      if (access_ok(VERIFY_READ, __gu_addr, size)) {              \
            switch (size) {                                 \
            case 1:                                         \
                  __get_user_asm("ub", __gu_val, __gu_addr, \
                               __gu_err);             \
                  break;                                    \
            case 2:                                         \
                  __get_user_asm("uh", __gu_val, __gu_addr, \
                               __gu_err);             \
                  break;                                    \
            case 4:                                         \
                  __get_user_asm("w", __gu_val, __gu_addr,  \
                               __gu_err);             \
                  break;                                    \
            default:                                  \
                  __gu_err = __get_user_bad();              \
                  break;                                    \
            }                                         \
      } else {                                        \
            __gu_err = -EFAULT;                             \
      }                                               \
      x = (typeof(*(ptr)))__gu_val;                         \
      __gu_err;                                       \
})

#define __get_user_asm(suffix, __gu_val, ptr, __gu_err)                 \
      asm volatile(                                         \
            "1:   ld." suffix "     %1, %3                  \n"   \
            "2:                                 \n"   \
            "     .section .fixup, \"ax\"             \n"   \
            "3:   mov   %0, %4                        \n"   \
            "     rjmp  2b                      \n"   \
            "     .previous                     \n"   \
            "     .section __ex_table, \"a\"          \n"   \
            "     .long 1b, 3b                        \n"   \
            "     .previous                     \n"   \
            : "=r"(__gu_err), "=r"(__gu_val)                \
            : "0"(__gu_err), "m"(*(ptr)), "i"(-EFAULT))

#define __put_user_nocheck(x, ptr, size)                    \
({                                                    \
      typeof(*(ptr)) __pu_val;                              \
      int __pu_err = 0;                               \
                                                      \
      __pu_val = (x);                                       \
      switch (size) {                                       \
      case 1: __put_user_asm("b", ptr, __pu_val, __pu_err); break;      \
      case 2: __put_user_asm("h", ptr, __pu_val, __pu_err); break;      \
      case 4: __put_user_asm("w", ptr, __pu_val, __pu_err); break;      \
      case 8: __put_user_asm("d", ptr, __pu_val, __pu_err); break;      \
      default: __pu_err = __put_user_bad(); break;                \
      }                                               \
      __pu_err;                                       \
})

#define __put_user_check(x, ptr, size)                            \
({                                                    \
      typeof(*(ptr)) __pu_val;                              \
      typeof(*(ptr)) __user *__pu_addr = (ptr);             \
      int __pu_err = 0;                               \
                                                      \
      __pu_val = (x);                                       \
      if (access_ok(VERIFY_WRITE, __pu_addr, size)) {             \
            switch (size) {                                 \
            case 1:                                         \
                  __put_user_asm("b", __pu_addr, __pu_val,  \
                               __pu_err);             \
                  break;                                    \
            case 2:                                         \
                  __put_user_asm("h", __pu_addr, __pu_val,  \
                               __pu_err);             \
                  break;                                    \
            case 4:                                         \
                  __put_user_asm("w", __pu_addr, __pu_val,  \
                               __pu_err);             \
                  break;                                    \
            case 8:                                         \
                  __put_user_asm("d", __pu_addr, __pu_val,        \
                               __pu_err);             \
                  break;                                    \
            default:                                  \
                  __pu_err = __put_user_bad();              \
                  break;                                    \
            }                                         \
      } else {                                        \
            __pu_err = -EFAULT;                             \
      }                                               \
      __pu_err;                                       \
})

#define __put_user_asm(suffix, ptr, __pu_val, __gu_err)                 \
      asm volatile(                                         \
            "1:   st." suffix "     %1, %3                  \n"   \
            "2:                                 \n"   \
            "     .section .fixup, \"ax\"             \n"   \
            "3:   mov   %0, %4                        \n"   \
            "     rjmp  2b                      \n"   \
            "     .previous                     \n"   \
            "     .section __ex_table, \"a\"          \n"   \
            "     .long 1b, 3b                        \n"   \
            "     .previous                     \n"   \
            : "=r"(__gu_err), "=m"(*(ptr))                        \
            : "0"(__gu_err), "r"(__pu_val), "i"(-EFAULT))

extern __kernel_size_t clear_user(void __user *addr, __kernel_size_t size);
extern __kernel_size_t __clear_user(void __user *addr, __kernel_size_t size);

extern long strncpy_from_user(char *dst, const char __user *src, long count);
extern long __strncpy_from_user(char *dst, const char __user *src, long count);

extern long strnlen_user(const char __user *__s, long __n);
extern long __strnlen_user(const char __user *__s, long __n);

#define strlen_user(s) strnlen_user(s, ~0UL >> 1)

struct exception_table_entry
{
      unsigned long insn, fixup;
};

#endif /* __ASM_AVR32_UACCESS_H */

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