/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2000
 *    Author(s): Hartmut Penner (hp@de.ibm.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  Derived from "include/asm-i386/uaccess.h"
 */
#ifndef __S390_UACCESS_H
#define __S390_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/ctl_reg.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(a)  ((mm_segment_t) { (a) })


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

#define get_ds()        (KERNEL_DS)
#define get_fs()        (current->thread.mm_segment)

#define set_fs(x) \
({                                                                      \
        unsigned long __pto;                                            \
        current->thread.mm_segment = (x);                               \
        __pto = current->thread.mm_segment.ar4 ?                        \
                S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
        __ctl_load(__pto, 7, 7);                                        \
})

#define segment_eq(a,b) ((a).ar4 == (b).ar4)

static inline int __range_ok(unsigned long addr, unsigned long size)
{
        return 1;
}

#define __access_ok(addr, size)                         \
({                                                      \
        __chk_user_ptr(addr);                           \
        __range_ok((unsigned long)(addr), (size));      \
})

#define access_ok(type, addr, size) __access_ok(addr, size)

/*
 * 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
{
        int insn, fixup;
};

static inline unsigned long extable_fixup(const struct exception_table_entry *x)
{
        return (unsigned long)&x->fixup + x->fixup;
}

#define ARCH_HAS_RELATIVE_EXTABLE

/**
 * __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 if pagefaults are
 *          enabled.
 *
 * 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.
 */
unsigned long __must_check __copy_from_user(void *to, const void __user *from,
                                            unsigned long n);

/**
 * __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 if pagefaults are
 *          enabled.
 *
 * 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.
 */
unsigned long __must_check __copy_to_user(void __user *to, const void *from,
                                          unsigned long n);

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES

#define __put_get_user_asm(to, from, size, spec)                \
({                                                              \
        register unsigned long __reg0 asm("0") = spec;          \
        int __rc;                                               \
                                                                \
        asm volatile(                                           \
                "0:     mvcos   %1,%3,%2\n"                     \
                "1:     xr      %0,%0\n"                        \
                "2:\n"                                          \
                ".pushsection .fixup, \"ax\"\n"                 \
                "3:     lhi     %0,%5\n"                        \
                "       jg      2b\n"                           \
                ".popsection\n"                                 \
                EX_TABLE(0b,3b) EX_TABLE(1b,3b)                 \
                : "=d" (__rc), "=Q" (*(to))                     \
                : "d" (size), "Q" (*(from)),                    \
                  "d" (__reg0), "K" (-EFAULT)                   \
                : "cc");                                        \
        __rc;                                                   \
})

#define __put_user_fn(x, ptr, size) __put_get_user_asm(ptr, x, size, 0x810000UL)
#define __get_user_fn(x, ptr, size) __put_get_user_asm(x, ptr, size, 0x81UL)

#else /* CONFIG_HAVE_MARCH_Z10_FEATURES */

static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
{
        size = __copy_to_user(ptr, x, size);
        return size ? -EFAULT : 0;
}

static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
{
        size = __copy_from_user(x, ptr, size);
        return size ? -EFAULT : 0;
}

#endif /* CONFIG_HAVE_MARCH_Z10_FEATURES */

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 */
#define __put_user(x, ptr) \
({                                                              \
        __typeof__(*(ptr)) __x = (x);                           \
        int __pu_err = -EFAULT;                                 \
        __chk_user_ptr(ptr);                                    \
        switch (sizeof (*(ptr))) {                              \
        case 1:                                                 \
        case 2:                                                 \
        case 4:                                                 \
        case 8:                                                 \
                __pu_err = __put_user_fn(&__x, ptr,             \
                                         sizeof(*(ptr)));       \
                break;                                          \
        default:                                                \
                __put_user_bad();                               \
                break;                                          \
         }                                                      \
        __pu_err;                                               \
})

#define put_user(x, ptr)                                        \
({                                                              \
        might_fault();                                          \
        __put_user(x, ptr);                                     \
})


int __put_user_bad(void) __attribute__((noreturn));

#define __get_user(x, ptr)                                      \
({                                                              \
        int __gu_err = -EFAULT;                                 \
        __chk_user_ptr(ptr);                                    \
        switch (sizeof(*(ptr))) {                               \
        case 1: {                                               \
                unsigned char __x;                              \
                __gu_err = __get_user_fn(&__x, ptr,             \
                                         sizeof(*(ptr)));       \
                (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                break;                                          \
        };                                                      \
        case 2: {                                               \
                unsigned short __x;                             \
                __gu_err = __get_user_fn(&__x, ptr,             \
                                         sizeof(*(ptr)));       \
                (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                break;                                          \
        };                                                      \
        case 4: {                                               \
                unsigned int __x;                               \
                __gu_err = __get_user_fn(&__x, ptr,             \
                                         sizeof(*(ptr)));       \
                (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                break;                                          \
        };                                                      \
        case 8: {                                               \
                unsigned long long __x;                         \
                __gu_err = __get_user_fn(&__x, ptr,             \
                                         sizeof(*(ptr)));       \
                (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                break;                                          \
        };                                                      \
        default:                                                \
                __get_user_bad();                               \
                break;                                          \
        }                                                       \
        __gu_err;                                               \
})

#define get_user(x, ptr)                                        \
({                                                              \
        might_fault();                                          \
        __get_user(x, ptr);                                     \
})

int __get_user_bad(void) __attribute__((noreturn));

#define __put_user_unaligned __put_user
#define __get_user_unaligned __get_user

/**
 * 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 if pagefaults are
 *          enabled.
 *
 * Copy data from kernel space to user space.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 */
static inline unsigned long __must_check
copy_to_user(void __user *to, const void *from, unsigned long n)
{
        might_fault();
        return __copy_to_user(to, from, n);
}

void copy_from_user_overflow(void)
#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
__compiletime_warning("copy_from_user() buffer size is not provably correct")
#endif
;

/**
 * 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 if pagefaults are
 *          enabled.
 *
 * 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.
 */
static inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
        unsigned int sz = __compiletime_object_size(to);

        might_fault();
        if (unlikely(sz != -1 && sz < n)) {
                copy_from_user_overflow();
                return n;
        }
        return __copy_from_user(to, from, n);
}

unsigned long __must_check
__copy_in_user(void __user *to, const void __user *from, unsigned long n);

static inline unsigned long __must_check
copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
        might_fault();
        return __copy_in_user(to, from, n);
}

/*
 * Copy a null terminated string from userspace.
 */

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

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

unsigned long __must_check __strnlen_user(const char __user *src, unsigned long count);

static inline unsigned long strnlen_user(const char __user *src, unsigned long n)
{
        might_fault();
        return __strnlen_user(src, n);
}

/**
 * strlen_user: - Get the size of a string in user space.
 * @str: The string to measure.
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * 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.
 */
#define strlen_user(str) strnlen_user(str, ~0UL)

/*
 * Zero Userspace
 */
unsigned long __must_check __clear_user(void __user *to, unsigned long size);

static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
        might_fault();
        return __clear_user(to, n);
}

int copy_to_user_real(void __user *dest, void *src, unsigned long count);
void s390_kernel_write(void *dst, const void *src, size_t size);

#endif /* __S390_UACCESS_H */