get_page_size_aarch64.h

static inline long get_page_size(void)
{
	/*
	 * aarch64 supports three values of page size: 4K, 16K
	 * and 64K which are selected at kernel compilation time.
	 * Therefore, we can't hard code the page size for this
	 * arch. Use the mmap() syscall return value to find the
	 * page size.
	 *
	 * Start the hinting the kernel with a multiple of 4K.
	 * If the page size is greater than 4K, the kernel will
	 * round it down to the nearest address that is multiple
	 * of page size. When that happens, our "if" checks below
	 * will catch the right page size.
	 */
	void *hint = (void *)0x444444441000;
	long page_size;
	void *p;
	long x;

	p = __sys_mmap(hint, 1, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
	if (IS_ERR(p))
		return PTR_ERR(p);

	x = (long) p;

	page_size = 64 * 1024;
	if ((x % page_size) == 0)
		goto out;

	page_size = 16 * 1024;
	if ((x % page_size) == 0)
		goto out;

	page_size = 4 * 1024;
	if ((x % page_size) == 0)
		goto out;

	/*
	 * Something goes wrong?
	 */
	page_size = -ENOTSUP;
out:
	__sys_munmap(p, 1);
	return page_size;
}