/*
 * include/asm-xtensa/uaccess.h
 *
 * User space memory access functions
 *
 * These routines provide basic accessing functions to the user memory
 * space for the kernel. This header file provides functions such as:
 *
 * 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) 2001 - 2005 Tensilica Inc.
 */

#ifndef _XTENSA_UACCESS_H
#define _XTENSA_UACCESS_H

#include <linux/prefetch.h>
#include <asm/types.h>
#include <asm/extable.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 (Data Segment Register?), these macros are
 * grossly misnamed.
 */

#define KERNEL_DS       ((mm_segment_t) { 0 })
#define USER_DS         ((mm_segment_t) { 1 })

#define get_fs()        (current->thread.current_ds)
#define set_fs(val)     (current->thread.current_ds = (val))

#define segment_eq(a, b)        ((a).seg == (b).seg)

#define __kernel_ok (uaccess_kernel())
#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(addr, size) __access_ok((unsigned long)(addr), (size))

#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)

/*
 * 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.
 *
 * Careful to not
 * (a) re-use the arguments for side effects (sizeof is ok)
 * (b) require any knowledge of processes at this stage
 */
#define put_user(x, ptr)        __put_user_check((x), (ptr), sizeof(*(ptr)))
#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * 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).
 */
#define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr)))
#define __get_user(x, ptr) __get_user_nocheck((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(__pu_addr, size))                 \
                __put_user_size((x), __pu_addr, (size), __pu_err);      \
        __pu_err;                                                       \
})

#define __put_user_size(x, ptr, size, retval)                           \
do {                                                                    \
        int __cb;                                                       \
        retval = 0;                                                     \
        switch (size) {                                                 \
        case 1: __put_user_asm(x, ptr, retval, 1, "s8i", __cb);  break; \
        case 2: __put_user_asm(x, ptr, retval, 2, "s16i", __cb); break; \
        case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break; \
        case 8: {                                                       \
                     __typeof__(*ptr) __v64 = x;                        \
                     retval = __copy_to_user(ptr, &__v64, 8);           \
                     break;                                             \
                }                                                       \
        default: __put_user_bad();                                      \
        }                                                               \
} while (0)


/*
 * Consider a case of a user single load/store would cause both an
 * unaligned exception and an MMU-related exception (unaligned
 * exceptions happen first):
 *
 * User code passes a bad variable ptr to a system call.
 * Kernel tries to access the variable.
 * Unaligned exception occurs.
 * Unaligned exception handler tries to make aligned accesses.
 * Double exception occurs for MMU-related cause (e.g., page not mapped).
 * do_page_fault() thinks the fault address belongs to the kernel, not the
 * user, and panics.
 *
 * The kernel currently prohibits user unaligned accesses.  We use the
 * __check_align_* macros to check for unaligned addresses before
 * accessing user space so we don't crash the kernel.  Both
 * __put_user_asm and __get_user_asm use these alignment macros, so
 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
 * sync.
 */

#define __check_align_1  ""

#define __check_align_2                         \
        "   _bbci.l %3,  0, 1f          \n"     \
        "   movi    %0, %4              \n"     \
        "   _j      2f                  \n"

#define __check_align_4                         \
        "   _bbsi.l %3,  0, 0f          \n"     \
        "   _bbci.l %3,  1, 1f          \n"     \
        "0: movi    %0, %4              \n"     \
        "   _j      2f                  \n"


/*
 * 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.
 *
 * WARNING: If you modify this macro at all, verify that the
 * __check_align_* macros still work.
 */
#define __put_user_asm(x, addr, err, align, insn, cb)   \
__asm__ __volatile__(                                   \
        __check_align_##align                           \
        "1: "insn"  %2, %3, 0           \n"             \
        "2:                             \n"             \
        "   .section  .fixup,\"ax\"     \n"             \
        "   .align 4                    \n"             \
        "   .literal_position           \n"             \
        "5:                             \n"             \
        "   movi   %1, 2b               \n"             \
        "   movi   %0, %4               \n"             \
        "   jx     %1                   \n"             \
        "   .previous                   \n"             \
        "   .section  __ex_table,\"a\"  \n"             \
        "   .long       1b, 5b          \n"             \
        "   .previous"                                  \
        :"=r" (err), "=r" (cb)                          \
        :"r" ((int)(x)), "r" (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) = (__force __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(__gu_addr, size))                 \
                __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                                       \
})

extern long __get_user_bad(void);

#define __get_user_size(x, ptr, size, retval)                           \
do {                                                                    \
        int __cb;                                                       \
        retval = 0;                                                     \
        switch (size) {                                                 \
        case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb);  break;\
        case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\
        case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb);  break;\
        case 8: retval = __copy_from_user(&x, ptr, 8);    break;        \
        default: (x) = __get_user_bad();                                \
        }                                                               \
} while (0)


/*
 * WARNING: If you modify this macro at all, verify that the
 * __check_align_* macros still work.
 */
#define __get_user_asm(x, addr, err, align, insn, cb) \
__asm__ __volatile__(                   \
        __check_align_##align                   \
        "1: "insn"  %2, %3, 0           \n"     \
        "2:                             \n"     \
        "   .section  .fixup,\"ax\"     \n"     \
        "   .align 4                    \n"     \
        "   .literal_position           \n"     \
        "5:                             \n"     \
        "   movi   %1, 2b               \n"     \
        "   movi   %2, 0                \n"     \
        "   movi   %0, %4               \n"     \
        "   jx     %1                   \n"     \
        "   .previous                   \n"     \
        "   .section  __ex_table,\"a\"  \n"     \
        "   .long       1b, 5b          \n"     \
        "   .previous"                          \
        :"=r" (err), "=r" (cb), "=r" (x)        \
        :"r" (addr), "i" (-EFAULT), "0" (err))


/*
 * Copy to/from user space
 */

extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);

static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
        prefetchw(to);
        return __xtensa_copy_user(to, (__force const void *)from, n);
}
static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
        prefetch(from);
        return __xtensa_copy_user((__force void *)to, from, n);
}
#define INLINE_COPY_FROM_USER
#define INLINE_COPY_TO_USER

/*
 * We need to return the number of bytes not cleared.  Our memset()
 * returns zero if a problem occurs while accessing user-space memory.
 * In that event, return no memory cleared.  Otherwise, zero for
 * success.
 */

static inline unsigned long
__xtensa_clear_user(void *addr, unsigned long size)
{
        if (!__memset(addr, 0, size))
                return size;
        return 0;
}

static inline unsigned long
clear_user(void *addr, unsigned long size)
{
        if (access_ok(addr, size))
                return __xtensa_clear_user(addr, size);
        return size ? -EFAULT : 0;
}

#define __clear_user  __xtensa_clear_user


#ifndef CONFIG_GENERIC_STRNCPY_FROM_USER

extern long __strncpy_user(char *, const char *, long);

static inline long
strncpy_from_user(char *dst, const char *src, long count)
{
        if (access_ok(src, 1))
                return __strncpy_user(dst, src, count);
        return -EFAULT;
}
#else
long strncpy_from_user(char *dst, const char *src, long count);
#endif

/*
 * Return the size of a string (including the ending 0!)
 */
extern long __strnlen_user(const char *, long);

static inline long 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);
}

#endif  /* _XTENSA_UACCESS_H */