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Fri, 07 Jul 2023 14:55:58 -0700 (PDT) Date: Fri, 7 Jul 2023 14:55:40 -0700 In-Reply-To: <20230707215540.2324998-1-axelrasmussen@google.com> Mime-Version: 1.0 References: <20230707215540.2324998-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230707215540.2324998-9-axelrasmussen@google.com> Subject: [PATCH v4 8/8] selftests/mm: add uffd unit test for UFFDIO_POISON From: Axel Rasmussen To: Alexander Viro , Andrew Morton , Brian Geffon , Christian Brauner , David Hildenbrand , Gaosheng Cui , Huang Ying , Hugh Dickins , James Houghton , "Jan Alexander Steffens (heftig)" , Jiaqi Yan , Jonathan Corbet , Kefeng Wang , "Liam R. Howlett" , Miaohe Lin , Mike Kravetz , "Mike Rapoport (IBM)" , Muchun Song , Nadav Amit , Naoya Horiguchi , Peter Xu , Ryan Roberts , Shuah Khan , Suleiman Souhlal , Suren Baghdasaryan , "T.J. Alumbaugh" , Yu Zhao , ZhangPeng Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Axel Rasmussen X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8458914000C X-Stat-Signature: 41qach83f487onisopb43ugw49mp4fj7 X-Rspam-User: X-HE-Tag: 1688766959-165084 X-HE-Meta: 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 YilZqq7L 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The test is pretty basic, and exercises UFFDIO_POISON straightforwardly. We register a region with userfaultfd, in missing fault mode. For each fault, we either UFFDIO_COPY a zeroed page (odd pages) or UFFDIO_POISON (even pages). We do this mix to test "something like a real use case", where guest memory would be some mix of poisoned and non-poisoned pages. We read each page in the region, and assert that the odd pages are zeroed as expected, and the even pages yield a SIGBUS as expected. Why UFFDIO_COPY instead of UFFDIO_ZEROPAGE? Because hugetlb doesn't support UFFDIO_ZEROPAGE, and we don't want to have special case code. Acked-by: Peter Xu Signed-off-by: Axel Rasmussen --- tools/testing/selftests/mm/uffd-unit-tests.c | 117 +++++++++++++++++++ 1 file changed, 117 insertions(+) diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index 04d91f144d1c..2709a34a39c5 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -951,6 +951,117 @@ static void uffd_zeropage_test(uffd_test_args_t *args) uffd_test_pass(); } +static void uffd_register_poison(int uffd, void *addr, uint64_t len) +{ + uint64_t ioctls = 0; + uint64_t expected = (1 << _UFFDIO_COPY) | (1 << _UFFDIO_POISON); + + if (uffd_register_with_ioctls(uffd, addr, len, true, + false, false, &ioctls)) + err("poison register fail"); + + if ((ioctls & expected) != expected) + err("registered area doesn't support COPY and POISON ioctls"); +} + +static void do_uffdio_poison(int uffd, unsigned long offset) +{ + struct uffdio_poison uffdio_poison = { 0 }; + int ret; + __s64 res; + + uffdio_poison.range.start = (unsigned long) area_dst + offset; + uffdio_poison.range.len = page_size; + uffdio_poison.mode = 0; + ret = ioctl(uffd, UFFDIO_POISON, &uffdio_poison); + res = uffdio_poison.updated; + + if (ret) + err("UFFDIO_POISON error: %"PRId64, (int64_t)res); + else if (res != page_size) + err("UFFDIO_POISON unexpected size: %"PRId64, (int64_t)res); +} + +static void uffd_poison_handle_fault( + struct uffd_msg *msg, struct uffd_args *args) +{ + unsigned long offset; + + if (msg->event != UFFD_EVENT_PAGEFAULT) + err("unexpected msg event %u", msg->event); + + if (msg->arg.pagefault.flags & + (UFFD_PAGEFAULT_FLAG_WP | UFFD_PAGEFAULT_FLAG_MINOR)) + err("unexpected fault type %llu", msg->arg.pagefault.flags); + + offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst; + offset &= ~(page_size-1); + + /* Odd pages -> copy zeroed page; even pages -> poison. */ + if (offset & page_size) + copy_page(uffd, offset, false); + else + do_uffdio_poison(uffd, offset); +} + +static void uffd_poison_test(uffd_test_args_t *targs) +{ + pthread_t uffd_mon; + char c; + struct uffd_args args = { 0 }; + struct sigaction act = { 0 }; + unsigned long nr_sigbus = 0; + unsigned long nr; + + fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); + + uffd_register_poison(uffd, area_dst, nr_pages * page_size); + memset(area_src, 0, nr_pages * page_size); + + args.handle_fault = uffd_poison_handle_fault; + if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) + err("uffd_poll_thread create"); + + sigbuf = &jbuf; + act.sa_sigaction = sighndl; + act.sa_flags = SA_SIGINFO; + if (sigaction(SIGBUS, &act, 0)) + err("sigaction"); + + for (nr = 0; nr < nr_pages; ++nr) { + unsigned long offset = nr * page_size; + const char *bytes = (const char *) area_dst + offset; + const char *i; + + if (sigsetjmp(*sigbuf, 1)) { + /* + * Access below triggered a SIGBUS, which was caught by + * sighndl, which then jumped here. Count this SIGBUS, + * and move on to next page. + */ + ++nr_sigbus; + continue; + } + + for (i = bytes; i < bytes + page_size; ++i) { + if (*i) + err("nonzero byte in area_dst (%p) at %p: %u", + area_dst, i, *i); + } + } + + if (write(pipefd[1], &c, sizeof(c)) != sizeof(c)) + err("pipe write"); + if (pthread_join(uffd_mon, NULL)) + err("pthread_join()"); + + if (nr_sigbus != nr_pages / 2) + err("expected to receive %lu SIGBUS, actually received %lu", + nr_pages / 2, nr_sigbus); + + uffd_test_pass(); +} + /* * Test the returned uffdio_register.ioctls with different register modes. * Note that _UFFDIO_ZEROPAGE is tested separately in the zeropage test. @@ -1126,6 +1237,12 @@ uffd_test_case_t uffd_tests[] = { UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_HUGETLBFS_SHMEM, }, + { + .name = "poison", + .uffd_fn = uffd_poison_test, + .mem_targets = MEM_ALL, + .uffd_feature_required = UFFD_FEATURE_POISON, + }, }; static void usage(const char *prog)