selftests/mm: move zeropage test into uffd unit tests

Simplifies it a bit along the way, e.g., drop the never used offset field
(which was always the 1st page so offset=0).

Introduce uffd_register_with_ioctls() out of uffd_register() to detect
uffdio_register.ioctls got returned.  Check that automatically when testing
UFFDIO_ZEROPAGE on different types of memory (and kernel).

Link: https://lkml.kernel.org/r/20230412164404.328815-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: 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>

tools/testing/selftests/mm/uffd-stress.c

@@ -109,15 +109,6 @@ static inline uint64_t uffd_minor_feature(void)
 		return 0;
 }
 
-static int my_bcmp(char *str1, char *str2, size_t n)
-{
-	unsigned long i;
-	for (i = 0; i < n; i++)
-		if (str1[i] != str2[i])
-			return 1;
-	return 0;
-}
-
 static void *locking_thread(void *arg)
 {
 	unsigned long cpu = (unsigned long) arg;
@@ -273,89 +264,6 @@ static int stress(struct uffd_args *args)
 	return 0;
 }
 
-static void retry_uffdio_zeropage(int ufd,
-				  struct uffdio_zeropage *uffdio_zeropage,
-				  unsigned long offset)
-{
-	uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
-				     uffdio_zeropage->range.len,
-				     offset);
-	if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
-		if (uffdio_zeropage->zeropage != -EEXIST)
-			err("UFFDIO_ZEROPAGE error: %"PRId64,
-			    (int64_t)uffdio_zeropage->zeropage);
-	} else {
-		err("UFFDIO_ZEROPAGE error: %"PRId64,
-		    (int64_t)uffdio_zeropage->zeropage);
-	}
-}
-
-static int __uffdio_zeropage(int ufd, unsigned long offset)
-{
-	struct uffdio_zeropage uffdio_zeropage;
-	int ret;
-	bool has_zeropage = !(test_type == TEST_HUGETLB);
-	__s64 res;
-
-	if (offset >= nr_pages * page_size)
-		err("unexpected offset %lu", offset);
-	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);
-	res = uffdio_zeropage.zeropage;
-	if (ret) {
-		/* real retval in ufdio_zeropage.zeropage */
-		if (has_zeropage)
-			err("UFFDIO_ZEROPAGE error: %"PRId64, (int64_t)res);
-		else if (res != -EINVAL)
-			err("UFFDIO_ZEROPAGE not -EINVAL");
-	} else if (has_zeropage) {
-		if (res != page_size) {
-			err("UFFDIO_ZEROPAGE unexpected size");
-		} else {
-			retry_uffdio_zeropage(ufd, &uffdio_zeropage,
-					      offset);
-			return 1;
-		}
-	} else
-		err("UFFDIO_ZEROPAGE succeeded");
-
-	return 0;
-}
-
-static int uffdio_zeropage(int ufd, unsigned long offset)
-{
-	return __uffdio_zeropage(ufd, offset);
-}
-
-/* exercise UFFDIO_ZEROPAGE */
-static int userfaultfd_zeropage_test(void)
-{
-	printf("testing UFFDIO_ZEROPAGE: ");
-	fflush(stdout);
-
-	uffd_test_ctx_init(0);
-
-	if (uffd_register(uffd, area_dst, nr_pages * page_size,
-			  true, test_uffdio_wp, false))
-		err("register failure");
-
-	if (area_dst_alias) {
-		/* Needed this to test zeropage-retry on shared memory */
-		if (uffd_register(uffd, area_dst_alias, nr_pages * page_size,
-				  true, test_uffdio_wp, false))
-			err("register failure");
-	}
-
-	if (uffdio_zeropage(uffd, 0))
-		if (my_bcmp(area_dst, zeropage, page_size))
-			err("zeropage is not zero");
-
-	printf("done.\n");
-	return 0;
-}
-
 static int userfaultfd_stress(void)
 {
 	void *area;
@@ -467,7 +375,7 @@ static int userfaultfd_stress(void)
 		uffd_stats_report(args, nr_cpus);
 	}
 
-	return userfaultfd_zeropage_test();
+	return 0;
 }
 
 static void set_test_type(const char *type)

tools/testing/selftests/mm/uffd-unit-tests.c

@@ -660,7 +660,100 @@ static void uffd_events_wp_test(void)
 	uffd_events_test_common(true);
 }
 
+static void retry_uffdio_zeropage(int ufd,
+				  struct uffdio_zeropage *uffdio_zeropage)
+{
+	uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
+				     uffdio_zeropage->range.len,
+				     0);
+	if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
+		if (uffdio_zeropage->zeropage != -EEXIST)
+			err("UFFDIO_ZEROPAGE error: %"PRId64,
+			    (int64_t)uffdio_zeropage->zeropage);
+	} else {
+		err("UFFDIO_ZEROPAGE error: %"PRId64,
+		    (int64_t)uffdio_zeropage->zeropage);
+	}
+}
+
+static bool do_uffdio_zeropage(int ufd, bool has_zeropage)
+{
+	struct uffdio_zeropage uffdio_zeropage = { 0 };
+	int ret;
+	__s64 res;
+
+	uffdio_zeropage.range.start = (unsigned long) area_dst;
+	uffdio_zeropage.range.len = page_size;
+	uffdio_zeropage.mode = 0;
+	ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
+	res = uffdio_zeropage.zeropage;
+	if (ret) {
+		/* real retval in ufdio_zeropage.zeropage */
+		if (has_zeropage)
+			err("UFFDIO_ZEROPAGE error: %"PRId64, (int64_t)res);
+		else if (res != -EINVAL)
+			err("UFFDIO_ZEROPAGE not -EINVAL");
+	} else if (has_zeropage) {
+		if (res != page_size)
+			err("UFFDIO_ZEROPAGE unexpected size");
+		else
+			retry_uffdio_zeropage(ufd, &uffdio_zeropage);
+		return true;
+	} else
+		err("UFFDIO_ZEROPAGE succeeded");
+
+	return false;
+}
+
+/*
+ * Registers a range with MISSING mode only for zeropage test.  Return true
+ * if UFFDIO_ZEROPAGE supported, false otherwise. Can't use uffd_register()
+ * because we want to detect .ioctls along the way.
+ */
+static bool
+uffd_register_detect_zeropage(int uffd, void *addr, uint64_t len)
+{
+	uint64_t ioctls = 0;
+
+	if (uffd_register_with_ioctls(uffd, addr, len, true,
+				      false, false, &ioctls))
+		err("zeropage register fail");
+
+	return ioctls & (1 << _UFFDIO_ZEROPAGE);
+}
+
+/* exercise UFFDIO_ZEROPAGE */
+static void uffd_zeropage_test(void)
+{
+	bool has_zeropage;
+	int i;
+
+	has_zeropage = uffd_register_detect_zeropage(uffd, area_dst, page_size);
+	if (area_dst_alias)
+		/* Ignore the retval; we already have it */
+		uffd_register_detect_zeropage(uffd, area_dst_alias, page_size);
+
+	if (do_uffdio_zeropage(uffd, has_zeropage))
+		for (i = 0; i < page_size; i++)
+			if (area_dst[i] != 0)
+				err("data non-zero at offset %d\n", i);
+
+	if (uffd_unregister(uffd, area_dst, page_size))
+		err("unregister");
+
+	if (area_dst_alias && uffd_unregister(uffd, area_dst_alias, page_size))
+		err("unregister");
+
+	uffd_test_pass();
+}
+
 uffd_test_case_t uffd_tests[] = {
+	{
+		.name = "zeropage",
+		.uffd_fn = uffd_zeropage_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = 0,
+	},
 	{
 		.name = "pagemap",
 		.uffd_fn = uffd_pagemap_test,

tools/testing/selftests/mm/vm_util.c

@@ -198,8 +198,9 @@ unsigned long default_huge_page_size(void)
 	return hps;
 }
 
-int uffd_register(int uffd, void *addr, uint64_t len,
-		  bool miss, bool wp, bool minor)
+/* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
+int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
+			      bool miss, bool wp, bool minor, uint64_t *ioctls)
 {
 	struct uffdio_register uffdio_register = { 0 };
 	uint64_t mode = 0;
@@ -218,10 +219,19 @@ int uffd_register(int uffd, void *addr, uint64_t len,
 
 	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1)
 		ret = -errno;
+	else if (ioctls)
+		*ioctls = uffdio_register.ioctls;
 
 	return ret;
 }
 
+int uffd_register(int uffd, void *addr, uint64_t len,
+		  bool miss, bool wp, bool minor)
+{
+	return uffd_register_with_ioctls(uffd, addr, len,
+					 miss, wp, minor, NULL);
+}
+
 int uffd_unregister(int uffd, void *addr, uint64_t len)
 {
 	struct uffdio_range range = { .start = (uintptr_t)addr, .len = len };

tools/testing/selftests/mm/vm_util.h

@@ -52,6 +52,8 @@ int uffd_open_dev(unsigned int flags);
 int uffd_open_sys(unsigned int flags);
 int uffd_open(unsigned int flags);
 int uffd_get_features(uint64_t *features);
+int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
+			      bool miss, bool wp, bool minor, uint64_t *ioctls);
 
 /*
  * On ppc64 this will only work with radix 2M hugepage size