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SubjectRe: [PATCH v3 7/7] selftest/mm: ksm_functional_tests: Add PROT_NONE test
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On 03.08.23 21:06, Peter Xu wrote:
> 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@redhat.com>
>
> [...]
>
>> +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..

Oh, indeed, thanks!

>
>> + ksft_test_result_fail("ptrace write failed\n");
>> + goto unmap;
>> + }
>> + }
>
> Acked-by: Peter Xu <peterx@redhat.com>
>

Thanks!

--
Cheers,

David / dhildenb

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