/* SPDX-License-Identifier: GPL-2.0 */
// Copyright (C) 2005-2017 Andes Technology Corporation

#ifndef _ASMANDES_UACCESS_H
#define _ASMANDES_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/sched.h>
#include <asm/errno.h>
#include <asm/memory.h>
#include <asm/types.h>

#define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"

/*
 * 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;
};

extern int fixup_exception(struct pt_regs *regs);

#define KERNEL_DS       ((mm_segment_t) { ~0UL })
#define USER_DS         ((mm_segment_t) {TASK_SIZE - 1})

#define get_fs()        (current_thread_info()->addr_limit)
#define user_addr_max   get_fs

static inline void set_fs(mm_segment_t fs)
{
        current_thread_info()->addr_limit = fs;
}

#define uaccess_kernel()        (get_fs() == KERNEL_DS)

#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs() -size))

#define access_ok(addr, size)   \
        __range_ok((unsigned long)addr, (unsigned long)size)
/*
 * Single-value transfer routines.  They automatically use the right
 * size if we just have the right pointer type.  Note that the functions
 * which read from user space (*get_*) need to take care not to leak
 * kernel data even if the calling code is buggy and fails to check
 * the return value.  This means zeroing out the destination variable
 * or buffer on error.  Normally this is done out of line by the
 * fixup code, but there are a few places where it intrudes on the
 * main code path.  When we only write to user space, there is no
 * problem.
 *
 * The "__xxx" versions of the user access functions do not verify the
 * address space - it must have been done previously with a separate
 * "access_ok()" call.
 *
 * The "xxx_error" versions set the third argument to EFAULT if an
 * error occurs, and leave it unchanged on success.  Note that these
 * versions are void (ie, don't return a value as such).
 */

#define get_user        __get_user                                      \

#define __get_user(x, ptr)                                              \
({                                                                      \
        long __gu_err = 0;                                              \
        __get_user_check((x), (ptr), __gu_err);                         \
        __gu_err;                                                       \
})

#define __get_user_error(x, ptr, err)                                   \
({                                                                      \
        __get_user_check((x), (ptr), (err));                            \
        (void)0;                                                        \
})

#define __get_user_check(x, ptr, err)                                   \
({                                                                      \
        const __typeof__(*(ptr)) __user *__p = (ptr);                   \
        might_fault();                                                  \
        if (access_ok(__p, sizeof(*__p))) {             \
                __get_user_err((x), __p, (err));                        \
        } else {                                                        \
                (x) = 0; (err) = -EFAULT;                               \
        }                                                               \
})

#define __get_user_err(x, ptr, err)                                     \
do {                                                                    \
        unsigned long __gu_val;                                         \
        __chk_user_ptr(ptr);                                            \
        switch (sizeof(*(ptr))) {                                       \
        case 1:                                                         \
                __get_user_asm("lbi", __gu_val, (ptr), (err));          \
                break;                                                  \
        case 2:                                                         \
                __get_user_asm("lhi", __gu_val, (ptr), (err));          \
                break;                                                  \
        case 4:                                                         \
                __get_user_asm("lwi", __gu_val, (ptr), (err));          \
                break;                                                  \
        case 8:                                                         \
                __get_user_asm_dword(__gu_val, (ptr), (err));           \
                break;                                                  \
        default:                                                        \
                BUILD_BUG();                                            \
                break;                                                  \
        }                                                               \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
} while (0)

#define __get_user_asm(inst, x, addr, err)                              \
        __asm__ __volatile__ (                                          \
                "1:     "inst"  %1,[%2]\n"                              \
                "2:\n"                                                  \
                "       .section .fixup,\"ax\"\n"                       \
                "       .align  2\n"                                    \
                "3:     move %0, %3\n"                                  \
                "       move %1, #0\n"                                  \
                "       b       2b\n"                                   \
                "       .previous\n"                                    \
                "       .section __ex_table,\"a\"\n"                    \
                "       .align  3\n"                                    \
                "       .long   1b, 3b\n"                               \
                "       .previous"                                      \
                : "+r" (err), "=&r" (x)                                 \
                : "r" (addr), "i" (-EFAULT)                             \
                : "cc")

#ifdef __NDS32_EB__
#define __gu_reg_oper0 "%H1"
#define __gu_reg_oper1 "%L1"
#else
#define __gu_reg_oper0 "%L1"
#define __gu_reg_oper1 "%H1"
#endif

#define __get_user_asm_dword(x, addr, err)                              \
        __asm__ __volatile__ (                                          \
                "\n1:\tlwi " __gu_reg_oper0 ",[%2]\n"                   \
                "\n2:\tlwi " __gu_reg_oper1 ",[%2+4]\n"                 \
                "3:\n"                                                  \
                "       .section .fixup,\"ax\"\n"                       \
                "       .align  2\n"                                    \
                "4:     move    %0, %3\n"                               \
                "       b       3b\n"                                   \
                "       .previous\n"                                    \
                "       .section __ex_table,\"a\"\n"                    \
                "       .align  3\n"                                    \
                "       .long   1b, 4b\n"                               \
                "       .long   2b, 4b\n"                               \
                "       .previous"                                      \
                : "+r"(err), "=&r"(x)                                   \
                : "r"(addr), "i"(-EFAULT)                               \
                : "cc")

#define put_user        __put_user                                      \

#define __put_user(x, ptr)                                              \
({                                                                      \
        long __pu_err = 0;                                              \
        __put_user_err((x), (ptr), __pu_err);                           \
        __pu_err;                                                       \
})

#define __put_user_error(x, ptr, err)                                   \
({                                                                      \
        __put_user_err((x), (ptr), (err));                              \
        (void)0;                                                        \
})

#define __put_user_check(x, ptr, err)                                   \
({                                                                      \
        __typeof__(*(ptr)) __user *__p = (ptr);                         \
        might_fault();                                                  \
        if (access_ok(__p, sizeof(*__p))) {             \
                __put_user_err((x), __p, (err));                        \
        } else  {                                                       \
                (err) = -EFAULT;                                        \
        }                                                               \
})

#define __put_user_err(x, ptr, err)                                     \
do {                                                                    \
        __typeof__(*(ptr)) __pu_val = (x);                              \
        __chk_user_ptr(ptr);                                            \
        switch (sizeof(*(ptr))) {                                       \
        case 1:                                                         \
                __put_user_asm("sbi", __pu_val, (ptr), (err));          \
                break;                                                  \
        case 2:                                                         \
                __put_user_asm("shi", __pu_val, (ptr), (err));          \
                break;                                                  \
        case 4:                                                         \
                __put_user_asm("swi", __pu_val, (ptr), (err));          \
                break;                                                  \
        case 8:                                                         \
                __put_user_asm_dword(__pu_val, (ptr), (err));           \
                break;                                                  \
        default:                                                        \
                BUILD_BUG();                                            \
                break;                                                  \
        }                                                               \
} while (0)

#define __put_user_asm(inst, x, addr, err)                              \
        __asm__ __volatile__ (                                          \
                "1:     "inst"  %1,[%2]\n"                              \
                "2:\n"                                                  \
                "       .section .fixup,\"ax\"\n"                       \
                "       .align  2\n"                                    \
                "3:     move    %0, %3\n"                               \
                "       b       2b\n"                                   \
                "       .previous\n"                                    \
                "       .section __ex_table,\"a\"\n"                    \
                "       .align  3\n"                                    \
                "       .long   1b, 3b\n"                               \
                "       .previous"                                      \
                : "+r" (err)                                            \
                : "r" (x), "r" (addr), "i" (-EFAULT)                    \
                : "cc")

#ifdef __NDS32_EB__
#define __pu_reg_oper0 "%H2"
#define __pu_reg_oper1 "%L2"
#else
#define __pu_reg_oper0 "%L2"
#define __pu_reg_oper1 "%H2"
#endif

#define __put_user_asm_dword(x, addr, err)                              \
        __asm__ __volatile__ (                                          \
                "\n1:\tswi " __pu_reg_oper0 ",[%1]\n"                   \
                "\n2:\tswi " __pu_reg_oper1 ",[%1+4]\n"                 \
                "3:\n"                                                  \
                "       .section .fixup,\"ax\"\n"                       \
                "       .align  2\n"                                    \
                "4:     move    %0, %3\n"                               \
                "       b       3b\n"                                   \
                "       .previous\n"                                    \
                "       .section __ex_table,\"a\"\n"                    \
                "       .align  3\n"                                    \
                "       .long   1b, 4b\n"                               \
                "       .long   2b, 4b\n"                               \
                "       .previous"                                      \
                : "+r"(err)                                             \
                : "r"(addr), "r"(x), "i"(-EFAULT)                       \
                : "cc")

extern unsigned long __arch_clear_user(void __user * addr, unsigned long n);
extern long strncpy_from_user(char *dest, const char __user * src, long count);
extern __must_check long strnlen_user(const char __user * str, long n);
extern unsigned long __arch_copy_from_user(void *to, const void __user * from,
                                           unsigned long n);
extern unsigned long __arch_copy_to_user(void __user * to, const void *from,
                                         unsigned long n);

#define raw_copy_from_user __arch_copy_from_user
#define raw_copy_to_user __arch_copy_to_user

#define INLINE_COPY_FROM_USER
#define INLINE_COPY_TO_USER
static inline unsigned long clear_user(void __user * to, unsigned long n)
{
        if (access_ok(to, n))
                n = __arch_clear_user(to, n);
        return n;
}

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

#endif /* _ASMNDS32_UACCESS_H */