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 axelrasmussen@google.com --- 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)