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Message-ID: <20230511182426.1898675-3-axelrasmussen@google.com>
Date: Thu, 11 May 2023 11:24:26 -0700
From: Axel Rasmussen <axelrasmussen@...gle.com>
To: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Christian Brauner <brauner@...nel.org>,
David Hildenbrand <david@...hat.com>,
Hongchen Zhang <zhanghongchen@...ngson.cn>,
Huang Ying <ying.huang@...el.com>,
James Houghton <jthoughton@...gle.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Miaohe Lin <linmiaohe@...wei.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Nadav Amit <namit@...are.com>,
Naoya Horiguchi <naoya.horiguchi@....com>,
Peter Xu <peterx@...hat.com>, Shuah Khan <shuah@...nel.org>,
ZhangPeng <zhangpeng362@...wei.com>
Cc: Axel Rasmussen <axelrasmussen@...gle.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: [PATCH 3/3] selftests/mm: add uffd unit test for UFFDIO_SIGBUS
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@...gle.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)
--
2.40.1.606.ga4b1b128d6-goog
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