函数源码

static inline int fault_in_pages_readable(const char __user *uaddr, int size)

    volatile char c;

    const char __user *end = uaddr + size - 1;

 

    if (unlikely(size == 0))

        return 0;

 

    if (unlikely(uaddr > end))

        return -EFAULT;

 

    do {

        if (unlikely(__get_user(c, uaddr) != 0))

            return -EFAULT;

    } while (uaddr <= end);

 

    if (((unsigned long)uaddr & PAGE_MASK) ==

        return __get_user(c, end);

 

    return 0;