On Thu, Aug 03, 2023 at 04:32:08PM +0200, David Hildenbrand wrote:
> Let's test whether merging and unmerging in PROT_NONE areas works as
> expected.
>
> Pass a page protection to mmap_and_merge_range(), which will trigger
> an mprotect() after writing to the pages, but before enabling merging.
>
> Make sure that unsharing works as expected, by performing a ptrace write
> (using /proc/self/mem) and by setting MADV_UNMERGEABLE.
>
> Note that this implicitly tests that ptrace writes in an inaccessible
> (PROT_NONE) mapping work as expected.
>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
[...]
> +static void test_prot_none(void)
> +{
> + const unsigned int size = 2 * MiB;
> + char *map;
> + int i;
> +
> + ksft_print_msg("[RUN] %s\n", __func__);
> +
> + map = mmap_and_merge_range(0x11, size, PROT_NONE, false);
> + if (map == MAP_FAILED)
> + goto unmap;
> +
> + /* Store a unique value in each page on one half using ptrace */
> + for (i = 0; i < size / 2; i += pagesize) {
> + lseek(mem_fd, (uintptr_t) map + i, SEEK_SET);
> + if (write(mem_fd, &i, sizeof(size)) != sizeof(size)) {
sizeof(i)? May not matter a huge lot, though..
> + ksft_test_result_fail("ptrace write failed\n");
> + goto unmap;
> + }
> + }
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
--
Peter Xu
