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Thu, 11 May 2023 11:24:37 -0700 (PDT) Date: Thu, 11 May 2023 11:24:26 -0700 In-Reply-To: <20230511182426.1898675-1-axelrasmussen@google.com> Mime-Version: 1.0 References: <20230511182426.1898675-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog Message-ID: <20230511182426.1898675-3-axelrasmussen@google.com> Subject: [PATCH 3/3] selftests/mm: add uffd unit test for UFFDIO_SIGBUS From: Axel Rasmussen To: Alexander Viro , Andrew Morton , Christian Brauner , David Hildenbrand , Hongchen Zhang , Huang Ying , James Houghton , "Liam R. Howlett" , Miaohe Lin , "Mike Rapoport (IBM)" , Nadav Amit , Naoya Horiguchi , Peter Xu , Shuah Khan , ZhangPeng Cc: Axel Rasmussen , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1F3561C0006 X-Stat-Signature: n48o6h4ccii7r6dz88qe8z4nhr7qkhh7 X-HE-Tag: 1683829477-909629 X-HE-Meta: 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 +1GtVHWv 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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_SIGBUS straightforwardly. We register a region with userfaultfd, in missing fault mode. For each fault, we either issue UFFDIO_ZEROPAGE (odd pages) or UFFDIO_SIGBUS (even 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. Signed-off-by: Axel Rasmussen --- tools/testing/selftests/mm/uffd-unit-tests.c | 114 ++++++++++++++++++- 1 file changed, 110 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index 269c86768a02..3eb5a6f9b51f 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -881,13 +881,13 @@ static void retry_uffdio_zeropage(int ufd, } } -static bool do_uffdio_zeropage(int ufd, bool has_zeropage) +static bool do_uffdio_zeropage(int ufd, bool has_zeropage, bool test_retry, unsigned long offset) { struct uffdio_zeropage uffdio_zeropage = { 0 }; int ret; __s64 res; - uffdio_zeropage.range.start = (unsigned long) area_dst; + uffdio_zeropage.range.start = (unsigned long) area_dst + offset; uffdio_zeropage.range.len = page_size; uffdio_zeropage.mode = 0; ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage); @@ -901,7 +901,7 @@ static bool do_uffdio_zeropage(int ufd, bool has_zeropage) } else if (has_zeropage) { if (res != page_size) err("UFFDIO_ZEROPAGE unexpected size"); - else + else if (test_retry) retry_uffdio_zeropage(ufd, &uffdio_zeropage); return true; } else @@ -938,7 +938,7 @@ static void uffd_zeropage_test(uffd_test_args_t *args) /* Ignore the retval; we already have it */ uffd_register_detect_zeropage(uffd, area_dst_alias, page_size); - if (do_uffdio_zeropage(uffd, has_zeropage)) + if (do_uffdio_zeropage(uffd, has_zeropage, true, 0)) for (i = 0; i < page_size; i++) if (area_dst[i] != 0) err("data non-zero at offset %d\n", i); @@ -952,6 +952,106 @@ static void uffd_zeropage_test(uffd_test_args_t *args) uffd_test_pass(); } +static void do_uffdio_sigbus(int uffd, unsigned long offset) +{ + struct uffdio_sigbus uffdio_sigbus = { 0 }; + int ret; + __s64 res; + + uffdio_sigbus.range.start = (unsigned long) area_dst + offset; + uffdio_sigbus.range.len = page_size; + uffdio_sigbus.mode = 0; + ret = ioctl(uffd, UFFDIO_SIGBUS, &uffdio_sigbus); + res = uffdio_sigbus.updated; + + if (ret) + err("UFFDIO_SIGBUS error: %"PRId64, (int64_t)res); + else if (res != page_size) + err("UFFDIO_SIGBUS unexpected size: %"PRId64, (int64_t)res); +} + +static void uffd_sigbus_ioctl_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 -> zeropage; even pages -> sigbus. */ + if (offset & page_size) { + if (!do_uffdio_zeropage(uffd, true, false, offset)) + err("UFFDIO_ZEROPAGE failed"); + } else { + do_uffdio_sigbus(uffd, offset); + } +} + +static void uffd_sigbus_ioctl_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); + + if (!uffd_register_detect_zeropage(uffd, area_dst, nr_pages * page_size)) + err("register failed: no zeropage support"); + + args.handle_fault = uffd_sigbus_ioctl_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. @@ -1127,6 +1227,12 @@ uffd_test_case_t uffd_tests[] = { UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_HUGETLBFS_SHMEM, }, + { + .name = "sigbus-ioctl", + .uffd_fn = uffd_sigbus_ioctl_test, + .mem_targets = MEM_ALL & ~(MEM_HUGETLB | MEM_HUGETLB_PRIVATE), + .uffd_feature_required = UFFD_FEATURE_SIGBUS_IOCTL, + }, }; static void usage(const char *prog)