selftests/mm: uffd_[un]register()

Add two helpers to register/unregister to an uffd.  Use them to drop
duplicate codes.

This patch also drops assert_expected_ioctls_present() and
get_expected_ioctls().  Reasons:

  - It'll need a lot of effort to pass test_type==HUGETLB into it from
    the upper, so it's the simplest way to get rid of another global var

  - The ioctls returned in UFFDIO_REGISTER is hardly useful at all,
    because any app can already detect kernel support on any ioctl via its
    corresponding UFFD_FEATURE_*.  The check here is for sanity mostly but
    it's probably destined no user app will even use it.

  - It's not friendly to one future goal of uffd to run on old
    kernels, the problem is get_expected_ioctls() compiles against
    UFFD_API_RANGE_IOCTLS, which is a value that can change depending on
    where the test is compiled, rather than reflecting what the kernel
    underneath has.  It means it'll report false negatives on old kernels
    so it's against our will.

So let's make our lives easier.

[peterx@redhat.com; tools/testing/selftests/mm/hugepage-mremap.c: add headers]
  Link: https://lkml.kernel.org/r/ZDxrvZh/cw357D8P@x1n
Link: https://lkml.kernel.org/r/20230412164247.328293-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 19 insertions, 64 deletions

diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
index c68a9aeefc41..e6d39a755082 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -463,28 +463,19 @@ static int uffdio_zeropage(int ufd, unsigned long offset)
 /* exercise UFFDIO_ZEROPAGE */
 static int userfaultfd_zeropage_test(void)
 {
-	struct uffdio_register uffdio_register;
-
 	printf("testing UFFDIO_ZEROPAGE: ");
 	fflush(stdout);
 
 	uffd_test_ctx_init(0);
 
-	uffdio_register.range.start = (unsigned long) area_dst;
-	uffdio_register.range.len = nr_pages * page_size;
-	uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
-	if (test_uffdio_wp)
-		uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  true, test_uffdio_wp, false))
 		err("register failure");
 
-	assert_expected_ioctls_present(
-		uffdio_register.mode, uffdio_register.ioctls);
-
 	if (area_dst_alias) {
 		/* Needed this to test zeropage-retry on shared memory */
-		uffdio_register.range.start = (unsigned long) area_dst_alias;
-		if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+		if (uffd_register(uffd, area_dst_alias, nr_pages * page_size,
+				  true, test_uffdio_wp, false))
 			err("register failure");
 	}
 
@@ -498,7 +489,6 @@ static int userfaultfd_zeropage_test(void)
 
 static int userfaultfd_events_test(void)
 {
-	struct uffdio_register uffdio_register;
 	pthread_t uffd_mon;
 	int err, features;
 	pid_t pid;
@@ -514,17 +504,10 @@ static int userfaultfd_events_test(void)
 
 	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 (test_uffdio_wp)
-		uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  true, test_uffdio_wp, false))
 		err("register failure");
 
-	assert_expected_ioctls_present(
-		uffdio_register.mode, uffdio_register.ioctls);
-
 	if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &stats))
 		err("uffd_poll_thread create");
 
@@ -550,7 +533,6 @@ static int userfaultfd_events_test(void)
 
 static int userfaultfd_sig_test(void)
 {
-	struct uffdio_register uffdio_register;
 	unsigned long userfaults;
 	pthread_t uffd_mon;
 	int err, features;
@@ -566,17 +548,10 @@ static int userfaultfd_sig_test(void)
 
 	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 (test_uffdio_wp)
-		uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  true, test_uffdio_wp, false))
 		err("register failure");
 
-	assert_expected_ioctls_present(
-		uffdio_register.mode, uffdio_register.ioctls);
-
 	if (faulting_process(1))
 		err("faulting process failed");
 
@@ -629,7 +604,6 @@ void check_memory_contents(char *p)
 static int userfaultfd_minor_test(void)
 {
 	unsigned long p;
-	struct uffdio_register uffdio_register;
 	pthread_t uffd_mon;
 	char c;
 	struct uffd_stats stats = { 0 };
@@ -642,17 +616,10 @@ static int userfaultfd_minor_test(void)
 
 	uffd_test_ctx_init(uffd_minor_feature());
 
-	uffdio_register.range.start = (unsigned long)area_dst_alias;
-	uffdio_register.range.len = nr_pages * page_size;
-	uffdio_register.mode = UFFDIO_REGISTER_MODE_MINOR;
-	if (test_uffdio_wp)
-		uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+	if (uffd_register(uffd, area_dst_alias, nr_pages * page_size,
+			  false, test_uffdio_wp, true))
 		err("register failure");
 
-	assert_expected_ioctls_present(
-		uffdio_register.mode, uffdio_register.ioctls);
-
 	/*
 	 * After registering with UFFD, populate the non-UFFD-registered side of
 	 * the shared mapping. This should *not* trigger any UFFD minor faults.
@@ -777,7 +744,6 @@ static void userfaultfd_wp_unpopulated_test(int pagemap_fd)
 
 static void userfaultfd_pagemap_test(unsigned int test_pgsize)
 {
-	struct uffdio_register uffdio_register;
 	int pagemap_fd;
 	uint64_t value;
 
@@ -805,10 +771,8 @@ static void userfaultfd_pagemap_test(unsigned int test_pgsize)
 			err("madvise(MADV_NOHUGEPAGE) failed");
 	}
 
-	uffdio_register.range.start = (unsigned long) area_dst;
-	uffdio_register.range.len = nr_pages * page_size;
-	uffdio_register.mode = UFFDIO_REGISTER_MODE_WP;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  false, true, false))
 		err("register failed");
 
 	pagemap_fd = pagemap_open();
@@ -858,8 +822,8 @@ static int userfaultfd_stress(void)
 {
 	void *area;
 	unsigned long nr;
-	struct uffdio_register uffdio_register;
 	struct uffd_stats uffd_stats[nr_cpus];
+	uint64_t mem_size = nr_pages * page_size;
 
 	uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED);
 
@@ -894,20 +858,13 @@ static int userfaultfd_stress(void)
 			fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);
 
 		/* register */
-		uffdio_register.range.start = (unsigned long) area_dst;
-		uffdio_register.range.len = nr_pages * page_size;
-		uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
-		if (test_uffdio_wp)
-			uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP;
-		if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+		if (uffd_register(uffd, area_dst, mem_size,
+				  true, test_uffdio_wp, false))
 			err("register failure");
-		assert_expected_ioctls_present(
-			uffdio_register.mode, uffdio_register.ioctls);
 
 		if (area_dst_alias) {
-			uffdio_register.range.start = (unsigned long)
-				area_dst_alias;
-			if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+			if (uffd_register(uffd, area_dst_alias, mem_size,
+					  true, test_uffdio_wp, false))
 				err("register failure alias");
 		}
 
@@ -949,12 +906,10 @@ static int userfaultfd_stress(void)
 				 nr_pages * page_size, false);
 
 		/* unregister */
-		if (ioctl(uffd, UFFDIO_UNREGISTER, &uffdio_register.range))
+		if (uffd_unregister(uffd, area_dst, mem_size))
 			err("unregister failure");
 		if (area_dst_alias) {
-			uffdio_register.range.start = (unsigned long) area_dst;
-			if (ioctl(uffd, UFFDIO_UNREGISTER,
-				  &uffdio_register.range))
+			if (uffd_unregister(uffd, area_dst_alias, mem_size))
 				err("unregister failure alias");
 		}