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selftests/mm: add uffd unit test for UFFDIO_POISON

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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.

Link: https://lkml.kernel.org/r/20230707215540.2324998-9-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Axel Rasmussen 2023-07-07 14:55:40 -07:00 committed by Andrew Morton
parent 7cf0f9e837
commit 99aa77215a
1 changed files with 117 additions and 0 deletions
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117
tools/testing/selftests/mm/uffd-unit-tests.c
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@ -951,6 +951,117 @@ static void uffd_zeropage_test(uffd_test_args_t *args)
uffd_test_pass();
}
static void uffd_register_poison(int uffd, void *addr, uint64_t len)
{
uint64_t ioctls = 0;
uint64_t expected = (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) != 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 = { 0 };
int ret;
__s64 res;
uffdio_poison.range.start = (unsigned long) area_dst + offset;
uffdio_poison.range.len = page_size;
uffdio_poison.mode = 0;
ret = ioctl(uffd, UFFDIO_POISON, &uffdio_poison);
res = uffdio_poison.updated;
if (ret)
err("UFFDIO_POISON error: %"PRId64, (int64_t)res);
else if (res != 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 != 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 -> 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 = { 0 };
struct sigaction act = { 0 };
unsigned long nr_sigbus = 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 = uffd_poison_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.
@ -1126,6 +1237,12 @@ uffd_test_case_t uffd_tests[] = {
UFFD_FEATURE_PAGEFAULT_FLAG_WP |
UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
},
{
.name = "poison",
.uffd_fn = uffd_poison_test,
.mem_targets = MEM_ALL,
.uffd_feature_required = UFFD_FEATURE_POISON,
},
};
static void usage(const char *prog)