#ifndef _PPC64_UACCESS_H
#define _PPC64_UACCESS_H

/* 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/pgtable.h>
#include <asm/processor.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 KERNEL_DS       ((mm_segment_t) { 0 })
#define USER_DS         ((mm_segment_t) { 1 })

#define get_ds()        (KERNEL_DS)
#define get_fs()        (current->thread.fs)
#define set_fs(val)     (current->thread.fs = (val))

#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))

static inline int verify_area(int type, const void * addr, unsigned long size)
{
        return access_ok(type,addr,size) ? 0 : -EFAULT;
}


/*
 * 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;
};

/* Returns 0 if exception not found and fixup otherwise.  */
extern unsigned long search_exception_table(unsigned long);
extern void sort_exception_table(void);

/*
 * 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 uglyness 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 the
 * PowerPC, 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_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;                                               \
})

#define __put_user_size(x,ptr,size,retval)                      \
do {                                                            \
        retval = 0;                                             \
        switch (size) {                                         \
          case 1: __put_user_asm(x,ptr,retval,"stb"); break;    \
          case 2: __put_user_asm(x,ptr,retval,"sth"); break;    \
          case 4: __put_user_asm(x,ptr,retval,"stw"); break;    \
          case 8: __put_user_asm(x,ptr,retval,"std"); break;    \
          default: __put_user_bad();                            \
        }                                                       \
} while (0)

/*
 * We don't tell gcc that we are accessing memory, but this is OK
 * because we do not write to any memory gcc knows about, so there
 * are no aliasing issues.
 */
#define __put_user_asm(x, addr, err, op)                        \
        __asm__ __volatile__(                                   \
                "1:     "op" %1,0(%2)\n"                        \
                "2:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "3:     li %0,%3\n"                             \
                "       b 2b\n"                                 \
                ".previous\n"                                   \
                ".section __ex_table,\"a\"\n"                   \
                "       .align 3\n"                             \
                "       .llong 1b,3b\n"                         \
                ".previous"                                     \
                : "=r"(err)                                     \
                : "r"(x), "b"(addr), "i"(-EFAULT), "0"(err))


#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);

#define __get_user_size(x,ptr,size,retval)                      \
do {                                                            \
        retval = 0;                                             \
        switch (size) {                                         \
          case 1: __get_user_asm(x,ptr,retval,"lbz"); break;    \
          case 2: __get_user_asm(x,ptr,retval,"lhz"); break;    \
          case 4: __get_user_asm(x,ptr,retval,"lwz"); break;    \
          case 8: __get_user_asm(x,ptr,retval,"ld");  break;    \
          default: (x) = __get_user_bad();                      \
        }                                                       \
} while (0)

#define __get_user_asm(x, addr, err, op)                \
        __asm__ __volatile__(                           \
                "1:     "op" %1,0(%2)\n"                \
                "2:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "3:     li %0,%3\n"                     \
                "       li %1,0\n"                      \
                "       b 2b\n"                         \
                ".previous\n"                           \
                ".section __ex_table,\"a\"\n"           \
                "       .align 3\n"                     \
                "       .llong 1b,3b\n"                 \
                ".previous"                             \
                : "=r"(err), "=r"(x)                    \
                : "b"(addr), "i"(-EFAULT), "0"(err))

/* more complex routines */

extern unsigned long __copy_tofrom_user(void *to, const void *from, unsigned long size);

static inline unsigned long
copy_from_user(void *to, const void *from, unsigned long n)
{
        unsigned long over;

        if (access_ok(VERIFY_READ, from, n))
                return __copy_tofrom_user(to, from, n);
        if ((unsigned long)from < TASK_SIZE) {
                over = (unsigned long)from + n - TASK_SIZE;
                return __copy_tofrom_user(to, from, n - over) + over;
        }
        return n;
}

static inline unsigned long
copy_to_user(void *to, const void *from, unsigned long n)
{
        unsigned long over;

        if (access_ok(VERIFY_WRITE, to, n))
                return __copy_tofrom_user(to, from, n);
        if ((unsigned long)to < TASK_SIZE) {
                over = (unsigned long)to + n - TASK_SIZE;
                return __copy_tofrom_user(to, from, n - over) + over;
        }
        return n;
}

#define __copy_from_user(to, from, size) \
        __copy_tofrom_user((to), (from), (size))
#define __copy_to_user(to, from, size) \
        __copy_tofrom_user((to), (from), (size))

extern unsigned long __clear_user(void *addr, unsigned long size);

static inline unsigned long
clear_user(void *addr, unsigned long size)
{
        if (access_ok(VERIFY_WRITE, addr, size))
                return __clear_user(addr, size);
        if ((unsigned long)addr < TASK_SIZE) {
                unsigned long over = (unsigned long)addr + size - TASK_SIZE;
                return __clear_user(addr, size - over) + over;
        }
        return size;
}

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

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

/*
 * Return the size of a string (including the ending 0)
 *
 * Return 0 for error
 */

extern int __strnlen_user(const char *str, long len, unsigned long top);

/*
 * Returns the length of the string at str (including the null byte),
 * or 0 if we hit a page we can't access,
 * or something > len if we didn't find a null byte.
 *
 * The `top' parameter to __strnlen_user is to make sure that
 * we can never overflow from the user area into kernel space.
 */
static inline int strnlen_user(const char *str, long len)
{
        unsigned long top = __kernel_ok? ~0UL: TASK_SIZE - 1;

        if ((unsigned long)str > top)
                return 0;
        return __strnlen_user(str, len, top);
}

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

#endif  /* __ASSEMBLY__ */

#endif  /* _PPC64_UACCESS_H */