uaccess.h

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#ifndef __SCORE_UACCESS_H
#define __SCORE_UACCESS_H

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/thread_info.h>

#define VERIFY_READ     0
#define VERIFY_WRITE        1

#define get_ds()        (KERNEL_DS)
#define get_fs()        (current_thread_info()->addr_limit)
#define segment_eq(a, b)    ((a).seg == (b).seg)

/*
 * Is a address valid? This does a straighforward calculation rather
 * than tests.
 *
 * Address valid if:
 *  - "addr" doesn't have any high-bits set
 *  - AND "size" doesn't have any high-bits set
 *  - AND "addr+size" doesn't have any high-bits set
 *  - OR we are in kernel mode.
 *
 * __ua_size() is a trick to avoid runtime checking of positive constant
 * sizes; for those we already know at compile time that the size is ok.
 */
#define __ua_size(size)                         \
    ((__builtin_constant_p(size) && (signed long) (size) > 0) ? 0 : (size))

/*
 * access_ok: - Checks if a user space pointer is valid
 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
 *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
 *        to write to a block, it is always safe to read from it.
 * @addr: User space pointer to start of block to check
 * @size: Size of block to check
 *
 * Context: User context only.  This function may sleep.
 *
 * Checks if a pointer to a block of memory in user space is valid.
 *
 * Returns true (nonzero) if the memory block may be valid, false (zero)
 * if it is definitely invalid.
 *
 * Note that, depending on architecture, this function probably just
 * checks that the pointer is in the user space range - after calling
 * this function, memory access functions may still return -EFAULT.
 */

#define __access_ok(addr, size)                 \
    (((long)((get_fs().seg) &               \
         ((addr) | ((addr) + (size)) |          \
          __ua_size(size)))) == 0)

#define access_ok(type, addr, size)             \
    likely(__access_ok((unsigned long)(addr), (size)))

/*
 * put_user: - Write a simple value into user space.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#define put_user(x, ptr) __put_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * get_user: - Get a simple variable from user space.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * __put_user: - Write a simple value into user space, with less checking.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr)))

/*
 * __get_user: - Get a simple variable from user space, with less checking.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
#define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr)))

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

/*
 * Yuck.  We need two variants, one for 64bit operation and one
 * for 32 bit mode and old iron.
 */
extern void __get_user_unknown(void);

#define __get_user_common(val, size, ptr)               \
do {                                    \
    switch (size) {                         \
    case 1:                             \
        __get_user_asm(val, "lb", ptr);             \
        break;                          \
    case 2:                             \
        __get_user_asm(val, "lh", ptr);             \
         break;                         \
    case 4:                             \
        __get_user_asm(val, "lw", ptr);             \
         break;                         \
    case 8:                             \
        if ((copy_from_user((void *)&val, ptr, 8)) == 0)    \
            __gu_err = 0;                   \
        else                            \
            __gu_err = -EFAULT;             \
        break;                          \
    default:                            \
        __get_user_unknown();                   \
        break;                          \
    }                               \
} while (0)

#define __get_user_nocheck(x, ptr, size)                \
({                                  \
    long __gu_err = 0;                      \
    __get_user_common((x), size, ptr);              \
    __gu_err;                           \
})

#define __get_user_check(x, ptr, size)                  \
({                                  \
    long __gu_err = -EFAULT;                    \
    const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
                                    \
    if (likely(access_ok(VERIFY_READ, __gu_ptr, size)))     \
        __get_user_common((x), size, __gu_ptr);         \
                                    \
    __gu_err;                           \
})

#define __get_user_asm(val, insn, addr)                 \
{                                   \
    long __gu_tmp;                          \
                                    \
    __asm__ __volatile__(                       \
        "1:" insn " %1, %3\n"                   \
        "2:\n"                          \
        ".section .fixup,\"ax\"\n"              \
        "3:li   %0, %4\n"                   \
        "j  2b\n"                       \
        ".previous\n"                       \
        ".section __ex_table,\"a\"\n"               \
        ".word  1b, 3b\n"                   \
        ".previous\n"                       \
        : "=r" (__gu_err), "=r" (__gu_tmp)          \
        : "0" (0), "o" (__m(addr)), "i" (-EFAULT));     \
                                    \
        (val) = (__typeof__(*(addr))) __gu_tmp;         \
}

/*
 * Yuck.  We need two variants, one for 64bit operation and one
 * for 32 bit mode and old iron.
 */
#define __put_user_nocheck(val, ptr, size)              \
({                                  \
    __typeof__(*(ptr)) __pu_val;                    \
    long __pu_err = 0;                      \
                                    \
    __pu_val = (val);                       \
    switch (size) {                         \
    case 1:                             \
        __put_user_asm("sb", ptr);              \
        break;                          \
    case 2:                             \
        __put_user_asm("sh", ptr);              \
        break;                          \
    case 4:                             \
        __put_user_asm("sw", ptr);              \
        break;                          \
    case 8:                             \
        if ((__copy_to_user((void *)ptr, &__pu_val, 8)) == 0)   \
            __pu_err = 0;                   \
        else                            \
            __pu_err = -EFAULT;             \
        break;                          \
    default:                            \
         __put_user_unknown();                  \
         break;                         \
    }                               \
    __pu_err;                           \
})


#define __put_user_check(val, ptr, size)                \
({                                  \
    __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
    __typeof__(*(ptr)) __pu_val = (val);                \
    long __pu_err = -EFAULT;                    \
                                    \
    if (likely(access_ok(VERIFY_WRITE, __pu_addr, size))) {     \
        switch (size) {                     \
        case 1:                         \
            __put_user_asm("sb", __pu_addr);        \
            break;                      \
        case 2:                         \
            __put_user_asm("sh", __pu_addr);        \
            break;                      \
        case 4:                         \
            __put_user_asm("sw", __pu_addr);        \
            break;                      \
        case 8:                         \
            if ((__copy_to_user((void *)__pu_addr, &__pu_val, 8)) == 0)\
                __pu_err = 0;               \
            else                        \
                __pu_err = -EFAULT;         \
            break;                      \
        default:                        \
            __put_user_unknown();               \
            break;                      \
        }                           \
    }                               \
    __pu_err;                           \
})

#define __put_user_asm(insn, ptr)                   \
    __asm__ __volatile__(                       \
        "1:" insn " %2, %3\n"                   \
        "2:\n"                          \
        ".section .fixup,\"ax\"\n"              \
        "3:li %0, %4\n"                     \
        "j 2b\n"                        \
        ".previous\n"                       \
        ".section __ex_table,\"a\"\n"               \
        ".word 1b, 3b\n"                    \
        ".previous\n"                       \
        : "=r" (__pu_err)                   \
        : "0" (0), "r" (__pu_val), "o" (__m(ptr)),      \
          "i" (-EFAULT));

extern void __put_user_unknown(void);
extern int __copy_tofrom_user(void *to, const void *from, unsigned long len);

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

    if (access_ok(VERIFY_READ, from, len))
        return __copy_tofrom_user(to, from, len);

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

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

    if (access_ok(VERIFY_WRITE, to, len))
        return __copy_tofrom_user(to, from, len);

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

#define __copy_from_user(to, from, len) \
        __copy_tofrom_user((to), (from), (len))

#define __copy_to_user(to, from, len)       \
        __copy_tofrom_user((to), (from), (len))

static inline unsigned long
__copy_to_user_inatomic(void *to, const void *from, unsigned long len)
{
    return __copy_to_user(to, from, len);
}

static inline unsigned long
__copy_from_user_inatomic(void *to, const void *from, unsigned long len)
{
    return __copy_from_user(to, from, len);
}

#define __copy_in_user(to, from, len)   __copy_from_user(to, from, len)

static inline unsigned long
copy_in_user(void *to, const void *from, unsigned long len)
{
    if (access_ok(VERIFY_READ, from, len) &&
              access_ok(VERFITY_WRITE, to, len))
        return copy_from_user(to, from, len);
}

/*
 * __clear_user: - Zero a block of memory in user space, with less checking.
 * @to:   Destination address, in user space.
 * @n:    Number of bytes to zero.
 *
 * Zero a block of memory in user space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be cleared.
 * On success, this will be zero.
 */
extern unsigned long __clear_user(void __user *src, unsigned long size);

static inline unsigned long clear_user(char *src, unsigned long size)
{
    if (access_ok(VERIFY_WRITE, src, size))
        return __clear_user(src, size);

    return -EFAULT;
}
/*
 * __strncpy_from_user: - Copy a NUL terminated string from userspace, with less checking.
 * @dst:   Destination address, in kernel space.  This buffer must be at
 *         least @count bytes long.
 * @src:   Source address, in user space.
 * @count: Maximum number of bytes to copy, including the trailing NUL.
 *
 * Copies a NUL-terminated string from userspace to kernel space.
 * Caller must check the specified block with access_ok() before calling
 * this function.
 *
 * On success, returns the length of the string (not including the trailing
 * NUL).
 *
 * If access to userspace fails, returns -EFAULT (some data may have been
 * copied).
 *
 * If @count is smaller than the length of the string, copies @count bytes
 * and returns @count.
 */
extern int __strncpy_from_user(char *dst, const char *src, long len);

static inline int strncpy_from_user(char *dst, const char *src, long len)
{
    if (access_ok(VERIFY_READ, src, 1))
        return __strncpy_from_user(dst, src, len);

    return -EFAULT;
}

extern int __strlen_user(const char *src);
static inline long strlen_user(const char __user *src)
{
    return __strlen_user(src);
}

extern int __strnlen_user(const char *str, long len);
static inline long strnlen_user(const char __user *str, long len)
{
    if (!access_ok(VERIFY_READ, str, 0))
        return 0;
    else        
        return __strnlen_user(str, len);
}

struct exception_table_entry {
    unsigned long insn;
    unsigned long fixup;
};

extern int fixup_exception(struct pt_regs *regs);

#endif /* __SCORE_UACCESS_H */