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SubjectRe: [RESEND PATCH v3 2/2] userfaultfd: selftest: Add tests for UFFD_FEATURE_SIGBUS feature
On Mon, Jul 31, 2017 at 09:54:06PM -0400, Prakash Sangappa wrote:
> This patch adds tests for UFFD_FEATURE_SIGBUS feature. The
> tests will verify signal delivery instead of userfault events.
> Also, test use of UFFDIO_COPY to allocate memory and retry
> accessing monitored area after signal delivery.
>
> This patch also fixes a bug in uffd_poll_thread() where 'uffd'
> is leaked.
>
> Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
> ---

Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>

> Change log
>
> v3: Eliminated use of sig_repeat variable and simplified error return.
>
> v2:
> - Added comments to explain the tests.
> - Fixed test to fail immediately if signal repeats.
> - Addressed other review comments.
>
> v1: https://lkml.org/lkml/2017/7/26/101
> ---
> tools/testing/selftests/vm/userfaultfd.c | 127 +++++++++++++++++++++++++++++-
> 1 files changed, 124 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index 1eae79a..52740ae 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -66,6 +66,7 @@
> #include <sys/wait.h>
> #include <pthread.h>
> #include <linux/userfaultfd.h>
> +#include <setjmp.h>
>
> #ifdef __NR_userfaultfd
>
> @@ -408,6 +409,7 @@ static int copy_page(int ufd, unsigned long offset)
> userfaults++;
> break;
> case UFFD_EVENT_FORK:
> + close(uffd);
> uffd = msg.arg.fork.ufd;
> pollfd[0].fd = uffd;
> break;
> @@ -572,6 +574,17 @@ static int userfaultfd_open(int features)
> return 0;
> }
>
> +sigjmp_buf jbuf, *sigbuf;
> +
> +static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
> +{
> + if (sig == SIGBUS) {
> + if (sigbuf)
> + siglongjmp(*sigbuf, 1);
> + abort();
> + }
> +}
> +
> /*
> * For non-cooperative userfaultfd test we fork() a process that will
> * generate pagefaults, will mremap the area monitored by the
> @@ -585,19 +598,59 @@ static int userfaultfd_open(int features)
> * The release of the pages currently generates event for shmem and
> * anonymous memory (UFFD_EVENT_REMOVE), hence it is not checked
> * for hugetlb.
> + * For signal test(UFFD_FEATURE_SIGBUS), signal_test = 1, we register
> + * monitored area, generate pagefaults and test that signal is delivered.
> + * Use UFFDIO_COPY to allocate missing page and retry. For signal_test = 2
> + * test robustness use case - we release monitored area, fork a process
> + * that will generate pagefaults and verify signal is generated.
> + * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
> + * feature. Using monitor thread, verify no userfault events are generated.
> */
> -static int faulting_process(void)
> +static int faulting_process(int signal_test)
> {
> unsigned long nr;
> unsigned long long count;
> unsigned long split_nr_pages;
> + unsigned long lastnr;
> + struct sigaction act;
> + unsigned long signalled = 0;
>
> if (test_type != TEST_HUGETLB)
> split_nr_pages = (nr_pages + 1) / 2;
> else
> split_nr_pages = nr_pages;
>
> + if (signal_test) {
> + sigbuf = &jbuf;
> + memset(&act, 0, sizeof(act));
> + act.sa_sigaction = sighndl;
> + act.sa_flags = SA_SIGINFO;
> + if (sigaction(SIGBUS, &act, 0)) {
> + perror("sigaction");
> + return 1;
> + }
> + lastnr = (unsigned long)-1;
> + }
> +
> for (nr = 0; nr < split_nr_pages; nr++) {
> + if (signal_test) {
> + if (sigsetjmp(*sigbuf, 1) != 0) {
> + if (nr == lastnr) {
> + fprintf(stderr, "Signal repeated\n");
> + return 1;
> + }
> +
> + lastnr = nr;
> + if (signal_test == 1) {
> + if (copy_page(uffd, nr * page_size))
> + signalled++;
> + } else {
> + signalled++;
> + continue;
> + }
> + }
> + }
> +
> count = *area_count(area_dst, nr);
> if (count != count_verify[nr]) {
> fprintf(stderr,
> @@ -607,6 +660,9 @@ static int faulting_process(void)
> }
> }
>
> + if (signal_test)
> + return signalled != split_nr_pages;
> +
> if (test_type == TEST_HUGETLB)
> return 0;
>
> @@ -761,7 +817,7 @@ static int userfaultfd_events_test(void)
> perror("fork"), exit(1);
>
> if (!pid)
> - return faulting_process();
> + return faulting_process(0);
>
> waitpid(pid, &err, 0);
> if (err)
> @@ -778,6 +834,70 @@ static int userfaultfd_events_test(void)
> return userfaults != nr_pages;
> }
>
> +static int userfaultfd_sig_test(void)
> +{
> + struct uffdio_register uffdio_register;
> + unsigned long expected_ioctls;
> + unsigned long userfaults;
> + pthread_t uffd_mon;
> + int err, features;
> + pid_t pid;
> + char c;
> +
> + printf("testing signal delivery: ");
> + fflush(stdout);
> +
> + if (uffd_test_ops->release_pages(area_dst))
> + return 1;
> +
> + features = UFFD_FEATURE_EVENT_FORK|UFFD_FEATURE_SIGBUS;
> + if (userfaultfd_open(features) < 0)
> + return 1;
> + fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
> +
> + uffdio_register.range.start = (unsigned long) area_dst;
> + uffdio_register.range.len = nr_pages * page_size;
> + uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
> + if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
> + fprintf(stderr, "register failure\n"), exit(1);
> +
> + expected_ioctls = uffd_test_ops->expected_ioctls;
> + if ((uffdio_register.ioctls & expected_ioctls) !=
> + expected_ioctls)
> + fprintf(stderr,
> + "unexpected missing ioctl for anon memory\n"),
> + exit(1);
> +
> + if (faulting_process(1))
> + fprintf(stderr, "faulting process failed\n"), exit(1);
> +
> + if (uffd_test_ops->release_pages(area_dst))
> + return 1;
> +
> + if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
> + perror("uffd_poll_thread create"), exit(1);
> +
> + pid = fork();
> + if (pid < 0)
> + perror("fork"), exit(1);
> +
> + if (!pid)
> + exit(faulting_process(2));
> +
> + waitpid(pid, &err, 0);
> + if (err)
> + fprintf(stderr, "faulting process failed\n"), exit(1);
> +
> + if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
> + perror("pipe write"), exit(1);
> + if (pthread_join(uffd_mon, (void **)&userfaults))
> + return 1;
> +
> + printf("done.\n");
> + printf(" Signal test userfaults: %ld\n", userfaults);
> + close(uffd);
> + return userfaults != 0;
> +}
> static int userfaultfd_stress(void)
> {
> void *area;
> @@ -946,7 +1066,8 @@ static int userfaultfd_stress(void)
> return err;
>
> close(uffd);
> - return userfaultfd_zeropage_test() || userfaultfd_events_test();
> + return userfaultfd_zeropage_test() || userfaultfd_sig_test()
> + || userfaultfd_events_test();
> }
>
> /*
> --
> 1.7.1
>
> --
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>

--
Sincerely yours,
Mike.

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