/*
 * OpenRISC Linux
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * OpenRISC implementation:
 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 * et al.
 *
 * 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 __ASM_OPENRISC_UACCESS_H
#define __ASM_OPENRISC_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/errno.h>
#include <linux/thread_info.h>
#include <linux/prefetch.h>
#include <linux/string.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.
 */

/* 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       (~0UL)
#define get_ds()        (KERNEL_DS)

#define USER_DS         (TASK_SIZE)
#define get_fs()        (current_thread_info()->addr_limit)
#define set_fs(x)       (current_thread_info()->addr_limit = (x))

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

/* Ensure that the range from addr to addr+size is all within the process'
 * address space
 */
#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs()-size))

/* Ensure that addr is below task's addr_limit */
#define __addr_ok(addr) ((unsigned long) addr < get_fs())

#define access_ok(type, addr, size) \
        __range_ok((unsigned long)addr, (unsigned long)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 {
        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, "l.sb"); break;          \
        case 2: __put_user_asm(x, ptr, retval, "l.sh"); break;          \
        case 4: __put_user_asm(x, ptr, retval, "l.sw"); break;          \
        case 8: __put_user_asm2(x, ptr, retval); break;                 \
        default: __put_user_bad();                                      \
        }                                                               \
} while (0)

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

/*
 * 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" 0(%2),%1\n"                        \
                "2:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "3:     l.addi %0,r0,%3\n"                      \
                "       l.j 2b\n"                               \
                "       l.nop\n"                                \
                ".previous\n"                                   \
                ".section __ex_table,\"a\"\n"                   \
                "       .align 2\n"                             \
                "       .long 1b,3b\n"                          \
                ".previous"                                     \
                : "=r"(err)                                     \
                : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))

#define __put_user_asm2(x, addr, err)                           \
        __asm__ __volatile__(                                   \
                "1:     l.sw 0(%2),%1\n"                        \
                "2:     l.sw 4(%2),%H1\n"                       \
                "3:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "4:     l.addi %0,r0,%3\n"                      \
                "       l.j 3b\n"                               \
                "       l.nop\n"                                \
                ".previous\n"                                   \
                ".section __ex_table,\"a\"\n"                   \
                "       .align 2\n"                             \
                "       .long 1b,4b\n"                          \
                "       .long 2b,4b\n"                          \
                ".previous"                                     \
                : "=r"(err)                                     \
                : "r"(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) = (__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, "l.lbz"); break;         \
        case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break;         \
        case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break;         \
        case 8: __get_user_asm2(x, ptr, retval);                        \
        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:     l.addi %0,r0,%3\n"              \
                "       l.addi %1,r0,0\n"               \
                "       l.j 2b\n"                       \
                "       l.nop\n"                        \
                ".previous\n"                           \
                ".section __ex_table,\"a\"\n"           \
                "       .align 2\n"                     \
                "       .long 1b,3b\n"                  \
                ".previous"                             \
                : "=r"(err), "=r"(x)                    \
                : "r"(addr), "i"(-EFAULT), "0"(err))

#define __get_user_asm2(x, addr, err)                   \
        __asm__ __volatile__(                           \
                "1:     l.lwz %1,0(%2)\n"               \
                "2:     l.lwz %H1,4(%2)\n"              \
                "3:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "4:     l.addi %0,r0,%3\n"              \
                "       l.addi %1,r0,0\n"               \
                "       l.addi %H1,r0,0\n"              \
                "       l.j 3b\n"                       \
                "       l.nop\n"                        \
                ".previous\n"                           \
                ".section __ex_table,\"a\"\n"           \
                "       .align 2\n"                     \
                "       .long 1b,4b\n"                  \
                "       .long 2b,4b\n"                  \
                ".previous"                             \
                : "=r"(err), "=&r"(x)                   \
                : "r"(addr), "i"(-EFAULT), "0"(err))

/* more complex routines */

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

#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)

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

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;
}

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

static inline __must_check 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;
}

#define user_addr_max() \
        (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)

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

extern __must_check long strlen_user(const char __user *str);
extern __must_check long strnlen_user(const char __user *str, long n);

#endif /* __ASM_OPENRISC_UACCESS_H */