C++ (Cpp) pin_page_for_write示例

示例#1

文件： uaccess_with_memcpy.c 项目： bongbongco/linux-rpi

unsigned long noinline
__copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
{
	unsigned long ua_flags;
	int atomic;

	if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
		memcpy((void *)to, from, n);
		return 0;
	}

	/* the mmap semaphore is taken only if not in an atomic context */
	atomic = faulthandler_disabled();

	if (!atomic)
		down_read(&current->mm->mmap_sem);
	while (n) {
		pte_t *pte;
		spinlock_t *ptl;
		int tocopy;

		while (!pin_page_for_write(to, &pte, &ptl)) {
			if (!atomic)
				up_read(&current->mm->mmap_sem);
			if (__put_user(0, (char __user *)to))
				goto out;
			if (!atomic)
				down_read(&current->mm->mmap_sem);
		}

		tocopy = (~(unsigned long)to & ~PAGE_MASK) + 1;
		if (tocopy > n)
			tocopy = n;

		ua_flags = uaccess_save_and_enable();
		memcpy((void *)to, from, tocopy);
		uaccess_restore(ua_flags);
		to += tocopy;
		from += tocopy;
		n -= tocopy;

		if (pte)
			pte_unmap_unlock(pte, ptl);
		else
			spin_unlock(ptl);
	}
	if (!atomic)
		up_read(&current->mm->mmap_sem);

out:
	return n;
}

示例#2

文件： uaccess_with_memcpy.c 项目： bongbongco/linux-rpi

static unsigned long noinline
__clear_user_memset(void __user *addr, unsigned long n)
{
	unsigned long ua_flags;

	if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
		memset((void *)addr, 0, n);
		return 0;
	}

	down_read(&current->mm->mmap_sem);
	while (n) {
		pte_t *pte;
		spinlock_t *ptl;
		int tocopy;

		while (!pin_page_for_write(addr, &pte, &ptl)) {
			up_read(&current->mm->mmap_sem);
			if (__put_user(0, (char __user *)addr))
				goto out;
			down_read(&current->mm->mmap_sem);
		}

		tocopy = (~(unsigned long)addr & ~PAGE_MASK) + 1;
		if (tocopy > n)
			tocopy = n;

		ua_flags = uaccess_save_and_enable();
		memset((void *)addr, 0, tocopy);
		uaccess_restore(ua_flags);
		addr += tocopy;
		n -= tocopy;

		if (pte)
			pte_unmap_unlock(pte, ptl);
		else
			spin_unlock(ptl);
	}
	up_read(&current->mm->mmap_sem);

out:
	return n;
}

示例#3

文件： uaccess_memcpy.c 项目： DentonGentry/gfiber-gfrg100

unsigned long ___copy_to_user(void *to, const void *from, unsigned long n)
{
	if (get_fs() == KERNEL_DS) {
		memcpy(to, from, n);
		return 0;
	}

	if (n < 256)
		return __arch_copy_to_user(to, from, n);

	down_read(&current->mm->mmap_sem);
	while (n) {
		pte_t *pte;
		spinlock_t *ptl;
		int tocopy;

		while (unlikely(!pin_page_for_write(to, &pte, &ptl))) {
			up_read(&current->mm->mmap_sem);
			if (put_user(*((u8 *)from), (u8 *)to))
				goto out;
			down_read(&current->mm->mmap_sem);
		}

		tocopy = ((~((unsigned long)to)) & (PAGE_SIZE - 1)) + 1;
		if (tocopy > n)
			tocopy = n;

		memcpy(to, from, tocopy);
		to += tocopy;
		from += tocopy;
		n -= tocopy;

		pte_unmap_unlock(pte, ptl);
	}

out:
	up_read(&current->mm->mmap_sem);

	return n;
}