static void optee_fill_pages_list()

in optee/smc_abi.c [381:432]

• 30 lines of code
• 5 McCabe index (conditional complexity)

static void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
				  size_t page_offset)
{
	int n = 0;
	phys_addr_t optee_page;
	/*
	 * Refer to OPTEE_MSG_ATTR_NONCONTIG description in optee_msg.h
	 * for details.
	 */
	struct {
		u64 pages_list[PAGELIST_ENTRIES_PER_PAGE];
		u64 next_page_data;
	} *pages_data;

	/*
	 * Currently OP-TEE uses 4k page size and it does not looks
	 * like this will change in the future.  On other hand, there are
	 * no know ARM architectures with page size < 4k.
	 * Thus the next built assert looks redundant. But the following
	 * code heavily relies on this assumption, so it is better be
	 * safe than sorry.
	 */
	BUILD_BUG_ON(PAGE_SIZE < OPTEE_MSG_NONCONTIG_PAGE_SIZE);

	pages_data = (void *)dst;
	/*
	 * If linux page is bigger than 4k, and user buffer offset is
	 * larger than 4k/8k/12k/etc this will skip first 4k pages,
	 * because they bear no value data for OP-TEE.
	 */
	optee_page = page_to_phys(*pages) +
		round_down(page_offset, OPTEE_MSG_NONCONTIG_PAGE_SIZE);

	while (true) {
		pages_data->pages_list[n++] = optee_page;

		if (n == PAGELIST_ENTRIES_PER_PAGE) {
			pages_data->next_page_data =
				virt_to_phys(pages_data + 1);
			pages_data++;
			n = 0;
		}

		optee_page += OPTEE_MSG_NONCONTIG_PAGE_SIZE;
		if (!(optee_page & ~PAGE_MASK)) {
			if (!--num_pages)
				break;
			pages++;
			optee_page = page_to_phys(*pages);
		}
	}
}