From nobody Mon Feb 9 14:32:51 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 743F0EB64D9 for ; Thu, 6 Jul 2023 22:51:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232446AbjGFWv6 (ORCPT ); Thu, 6 Jul 2023 18:51:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230504AbjGFWvZ (ORCPT ); Thu, 6 Jul 2023 18:51:25 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03953212B for ; Thu, 6 Jul 2023 15:51:07 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-577323ba3d5so34200597b3.0 for ; Thu, 06 Jul 2023 15:51:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1688683866; x=1691275866; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=vNyM+7c0est1wcVkLGeYyWS2zFzaKr32nANrKlDiGpI=; b=EK01mLypW26xwbB17tl+WVi77pgJ0OApJdOy0ZdOVv84/lYvfVuW7WowZ4rEK8f7WX g4rTBFdn/gfopVFptl2AY7oR1MbOxcuKJ5NLlgJS4KZnwJQ/O9DYar58Cp6+LJtem2dz 7aV6c0xPB8rtx/DVLBBYyqqPk4Y5aP7bx24BzHZVQh7fjXNIuWh3WsjiPncdyuOWOy0f szlc4nj/Zd3/Khbkib9ISdsge3HmKG+4el8u83yJEUvEUWR2sl14PZi/zm9NTrqicFDS XKFqXwSRFH+ICd8i9r7ldw2FSna2YUHpUhgptiJGArRniVNPuiWl7n0jMNBuoRiJ6+di 6/Tw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688683866; x=1691275866; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vNyM+7c0est1wcVkLGeYyWS2zFzaKr32nANrKlDiGpI=; b=MiVtaur8dsEFqm7U+jRnBwbVzf5CP6XpY3m9yVy2kipotrwguSiG8l0YqB94DruQLt VpY6rXHcU4fXrgObm7WvjBYIuwumXLt4VdT2QsWK+OpEPHP/1zRlU/CHjdRLAiajbEE+ Lg+0rvZYLk+Rd4ruH5wcKH1QMjOq/LCUNsZQeZCCUEhO+MzuHYe4o4KZNfwpzmW4IcIf Rcwvnd765fORoohaPa9IzToTddgtc+Hn0G5PnnE5NokMirDI9sM75u8QnWCuN8B14Qhv yGUV7zLxD9GkVS6r6sgCuZPK92hJcUuSbuei4x7pEJuEbTspWS9lk6OIDD8qH4NtQvi5 +qgQ== X-Gm-Message-State: ABy/qLaJZtFFAjCBhm7rxszFJkgqeCLfiDKLa7n82Gh5qDIpOQJfUh1x ciKCKq7xz7mnoAubqfJAWKZZUQ4I79o+eVSyb3NO X-Google-Smtp-Source: APBJJlHgoq6fX5m1+Roj1PD+nUlgNcdctSDPa98kXCzajWjYbfEt4nefdrt/24V9AOah7Hkvx+a3A+kIbPjrz61F6Iqg X-Received: from axel.svl.corp.google.com ([2620:15c:2a3:200:bec3:2b1c:87a:fca2]) (user=axelrasmussen job=sendgmr) by 2002:a25:ab90:0:b0:bc4:a660:528f with SMTP id v16-20020a25ab90000000b00bc4a660528fmr39975ybi.5.1688683866544; Thu, 06 Jul 2023 15:51:06 -0700 (PDT) Date: Thu, 6 Jul 2023 15:50:36 -0700 In-Reply-To: <20230706225037.1164380-1-axelrasmussen@google.com> Mime-Version: 1.0 References: <20230706225037.1164380-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230706225037.1164380-9-axelrasmussen@google.com> Subject: [PATCH v3 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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/s= elftests/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(); } =20 +static void uffd_register_poison(int uffd, void *addr, uint64_t len) +{ + uint64_t ioctls =3D 0; + uint64_t expected =3D (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) !=3D 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 =3D { 0 }; + int ret; + __s64 res; + + uffdio_poison.range.start =3D (unsigned long) area_dst + offset; + uffdio_poison.range.len =3D page_size; + uffdio_poison.mode =3D 0; + ret =3D ioctl(uffd, UFFDIO_POISON, &uffdio_poison); + res =3D uffdio_poison.updated; + + if (ret) + err("UFFDIO_POISON error: %"PRId64, (int64_t)res); + else if (res !=3D 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 !=3D 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 =3D (char *)(unsigned long)msg->arg.pagefault.address - area_dst; + offset &=3D ~(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 =3D { 0 }; + struct sigaction act =3D { 0 }; + unsigned long nr_sigbus =3D 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 =3D uffd_poison_handle_fault; + if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) + err("uffd_poll_thread create"); + + sigbuf =3D &jbuf; + act.sa_sigaction =3D sighndl; + act.sa_flags =3D SA_SIGINFO; + if (sigaction(SIGBUS, &act, 0)) + err("sigaction"); + + for (nr =3D 0; nr < nr_pages; ++nr) { + unsigned long offset =3D nr * page_size; + const char *bytes =3D (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 =3D 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)) !=3D sizeof(c)) + err("pipe write"); + if (pthread_join(uffd_mon, NULL)) + err("pthread_join()"); + + if (nr_sigbus !=3D 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[] =3D { UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_HUGETLBFS_SHMEM, }, + { + .name =3D "poison", + .uffd_fn =3D uffd_poison_test, + .mem_targets =3D MEM_ALL, + .uffd_feature_required =3D UFFD_FEATURE_POISON, + }, }; =20 static void usage(const char *prog) --=20 2.41.0.255.g8b1d071c50-goog