1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Userfaultfd unit tests.
4 *
5 * Copyright (C) 2015-2023 Red Hat, Inc.
6 */
7
8 #include "uffd-common.h"
9
10 #include "../../../../mm/gup_test.h"
11
12 #ifdef __NR_userfaultfd
13
14 /* The unit test doesn't need a large or random size, make it 32MB for now */
15 #define UFFD_TEST_MEM_SIZE (32UL << 20)
16
17 #define MEM_ANON BIT_ULL(0)
18 #define MEM_SHMEM BIT_ULL(1)
19 #define MEM_SHMEM_PRIVATE BIT_ULL(2)
20 #define MEM_HUGETLB BIT_ULL(3)
21 #define MEM_HUGETLB_PRIVATE BIT_ULL(4)
22
23 #define MEM_ALL (MEM_ANON | MEM_SHMEM | MEM_SHMEM_PRIVATE | \
24 MEM_HUGETLB | MEM_HUGETLB_PRIVATE)
25
26 struct mem_type {
27 const char *name;
28 unsigned int mem_flag;
29 uffd_test_ops_t *mem_ops;
30 bool shared;
31 };
32 typedef struct mem_type mem_type_t;
33
34 mem_type_t mem_types[] = {
35 {
36 .name = "anon",
37 .mem_flag = MEM_ANON,
38 .mem_ops = &anon_uffd_test_ops,
39 .shared = false,
40 },
41 {
42 .name = "shmem",
43 .mem_flag = MEM_SHMEM,
44 .mem_ops = &shmem_uffd_test_ops,
45 .shared = true,
46 },
47 {
48 .name = "shmem-private",
49 .mem_flag = MEM_SHMEM_PRIVATE,
50 .mem_ops = &shmem_uffd_test_ops,
51 .shared = false,
52 },
53 {
54 .name = "hugetlb",
55 .mem_flag = MEM_HUGETLB,
56 .mem_ops = &hugetlb_uffd_test_ops,
57 .shared = true,
58 },
59 {
60 .name = "hugetlb-private",
61 .mem_flag = MEM_HUGETLB_PRIVATE,
62 .mem_ops = &hugetlb_uffd_test_ops,
63 .shared = false,
64 },
65 };
66
67 /* Arguments to be passed over to each uffd unit test */
68 struct uffd_test_args {
69 mem_type_t *mem_type;
70 };
71 typedef struct uffd_test_args uffd_test_args_t;
72
73 /* Returns: UFFD_TEST_* */
74 typedef void (*uffd_test_fn)(uffd_test_args_t *);
75
76 typedef struct {
77 const char *name;
78 uffd_test_fn uffd_fn;
79 unsigned int mem_targets;
80 uint64_t uffd_feature_required;
81 } uffd_test_case_t;
82
uffd_test_report(void)83 static void uffd_test_report(void)
84 {
85 printf("Userfaults unit tests: pass=%u, skip=%u, fail=%u (total=%u)\n",
86 ksft_get_pass_cnt(),
87 ksft_get_xskip_cnt(),
88 ksft_get_fail_cnt(),
89 ksft_test_num());
90 }
91
uffd_test_pass(void)92 static void uffd_test_pass(void)
93 {
94 printf("done\n");
95 ksft_inc_pass_cnt();
96 }
97
98 #define uffd_test_start(...) do { \
99 printf("Testing "); \
100 printf(__VA_ARGS__); \
101 printf("... "); \
102 fflush(stdout); \
103 } while (0)
104
105 #define uffd_test_fail(...) do { \
106 printf("failed [reason: "); \
107 printf(__VA_ARGS__); \
108 printf("]\n"); \
109 ksft_inc_fail_cnt(); \
110 } while (0)
111
uffd_test_skip(const char * message)112 static void uffd_test_skip(const char *message)
113 {
114 printf("skipped [reason: %s]\n", message);
115 ksft_inc_xskip_cnt();
116 }
117
118 /*
119 * Returns 1 if specific userfaultfd supported, 0 otherwise. Note, we'll
120 * return 1 even if some test failed as long as uffd supported, because in
121 * that case we still want to proceed with the rest uffd unit tests.
122 */
test_uffd_api(bool use_dev)123 static int test_uffd_api(bool use_dev)
124 {
125 struct uffdio_api uffdio_api;
126 int uffd;
127
128 uffd_test_start("UFFDIO_API (with %s)",
129 use_dev ? "/dev/userfaultfd" : "syscall");
130
131 if (use_dev)
132 uffd = uffd_open_dev(UFFD_FLAGS);
133 else
134 uffd = uffd_open_sys(UFFD_FLAGS);
135 if (uffd < 0) {
136 uffd_test_skip("cannot open userfaultfd handle");
137 return 0;
138 }
139
140 /* Test wrong UFFD_API */
141 uffdio_api.api = 0xab;
142 uffdio_api.features = 0;
143 if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
144 uffd_test_fail("UFFDIO_API should fail with wrong api but didn't");
145 goto out;
146 }
147
148 /* Test wrong feature bit */
149 uffdio_api.api = UFFD_API;
150 uffdio_api.features = BIT_ULL(63);
151 if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
152 uffd_test_fail("UFFDIO_API should fail with wrong feature but didn't");
153 goto out;
154 }
155
156 /* Test normal UFFDIO_API */
157 uffdio_api.api = UFFD_API;
158 uffdio_api.features = 0;
159 if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
160 uffd_test_fail("UFFDIO_API should succeed but failed");
161 goto out;
162 }
163
164 /* Test double requests of UFFDIO_API with a random feature set */
165 uffdio_api.features = BIT_ULL(0);
166 if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
167 uffd_test_fail("UFFDIO_API should reject initialized uffd");
168 goto out;
169 }
170
171 uffd_test_pass();
172 out:
173 close(uffd);
174 /* We have a valid uffd handle */
175 return 1;
176 }
177
178 /*
179 * This function initializes the global variables. TODO: remove global
180 * vars and then remove this.
181 */
182 static int
uffd_setup_environment(uffd_test_args_t * args,uffd_test_case_t * test,mem_type_t * mem_type,const char ** errmsg)183 uffd_setup_environment(uffd_test_args_t *args, uffd_test_case_t *test,
184 mem_type_t *mem_type, const char **errmsg)
185 {
186 map_shared = mem_type->shared;
187 uffd_test_ops = mem_type->mem_ops;
188
189 if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB))
190 page_size = default_huge_page_size();
191 else
192 page_size = psize();
193
194 nr_pages = UFFD_TEST_MEM_SIZE / page_size;
195 /* TODO: remove this global var.. it's so ugly */
196 nr_cpus = 1;
197
198 /* Initialize test arguments */
199 args->mem_type = mem_type;
200
201 return uffd_test_ctx_init(test->uffd_feature_required, errmsg);
202 }
203
uffd_feature_supported(uffd_test_case_t * test)204 static bool uffd_feature_supported(uffd_test_case_t *test)
205 {
206 uint64_t features;
207
208 if (uffd_get_features(&features))
209 return false;
210
211 return (features & test->uffd_feature_required) ==
212 test->uffd_feature_required;
213 }
214
pagemap_open(void)215 static int pagemap_open(void)
216 {
217 int fd = open("/proc/self/pagemap", O_RDONLY);
218
219 if (fd < 0)
220 err("open pagemap");
221
222 return fd;
223 }
224
225 /* This macro let __LINE__ works in err() */
226 #define pagemap_check_wp(value, wp) do { \
227 if (!!(value & PM_UFFD_WP) != wp) \
228 err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \
229 } while (0)
230
231 typedef struct {
232 int parent_uffd, child_uffd;
233 } fork_event_args;
234
fork_event_consumer(void * data)235 static void *fork_event_consumer(void *data)
236 {
237 fork_event_args *args = data;
238 struct uffd_msg msg = { 0 };
239
240 /* Read until a full msg received */
241 while (uffd_read_msg(args->parent_uffd, &msg));
242
243 if (msg.event != UFFD_EVENT_FORK)
244 err("wrong message: %u\n", msg.event);
245
246 /* Just to be properly freed later */
247 args->child_uffd = msg.arg.fork.ufd;
248 return NULL;
249 }
250
251 typedef struct {
252 int gup_fd;
253 bool pinned;
254 } pin_args;
255
256 /*
257 * Returns 0 if succeed, <0 for errors. pin_pages() needs to be paired
258 * with unpin_pages(). Currently it needs to be RO longterm pin to satisfy
259 * all needs of the test cases (e.g., trigger unshare, trigger fork() early
260 * CoW, etc.).
261 */
pin_pages(pin_args * args,void * buffer,size_t size)262 static int pin_pages(pin_args *args, void *buffer, size_t size)
263 {
264 struct pin_longterm_test test = {
265 .addr = (uintptr_t)buffer,
266 .size = size,
267 /* Read-only pins */
268 .flags = 0,
269 };
270
271 if (args->pinned)
272 err("already pinned");
273
274 args->gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
275 if (args->gup_fd < 0)
276 return -errno;
277
278 if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_START, &test)) {
279 /* Even if gup_test existed, can be an old gup_test / kernel */
280 close(args->gup_fd);
281 return -errno;
282 }
283 args->pinned = true;
284 return 0;
285 }
286
unpin_pages(pin_args * args)287 static void unpin_pages(pin_args *args)
288 {
289 if (!args->pinned)
290 err("unpin without pin first");
291 if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_STOP))
292 err("PIN_LONGTERM_TEST_STOP");
293 close(args->gup_fd);
294 args->pinned = false;
295 }
296
pagemap_test_fork(int uffd,bool with_event,bool test_pin)297 static int pagemap_test_fork(int uffd, bool with_event, bool test_pin)
298 {
299 fork_event_args args = { .parent_uffd = uffd, .child_uffd = -1 };
300 pthread_t thread;
301 pid_t child;
302 uint64_t value;
303 int fd, result;
304
305 /* Prepare a thread to resolve EVENT_FORK */
306 if (with_event) {
307 if (pthread_create(&thread, NULL, fork_event_consumer, &args))
308 err("pthread_create()");
309 }
310
311 child = fork();
312 if (!child) {
313 /* Open the pagemap fd of the child itself */
314 pin_args args = {};
315
316 fd = pagemap_open();
317
318 if (test_pin && pin_pages(&args, area_dst, page_size))
319 /*
320 * Normally when reach here we have pinned in
321 * previous tests, so shouldn't fail anymore
322 */
323 err("pin page failed in child");
324
325 value = pagemap_get_entry(fd, area_dst);
326 /*
327 * After fork(), we should handle uffd-wp bit differently:
328 *
329 * (1) when with EVENT_FORK, it should persist
330 * (2) when without EVENT_FORK, it should be dropped
331 */
332 pagemap_check_wp(value, with_event);
333 if (test_pin)
334 unpin_pages(&args);
335 /* Succeed */
336 exit(0);
337 }
338 waitpid(child, &result, 0);
339
340 if (with_event) {
341 if (pthread_join(thread, NULL))
342 err("pthread_join()");
343 if (args.child_uffd < 0)
344 err("Didn't receive child uffd");
345 close(args.child_uffd);
346 }
347
348 return result;
349 }
350
uffd_wp_unpopulated_test(uffd_test_args_t * args)351 static void uffd_wp_unpopulated_test(uffd_test_args_t *args)
352 {
353 uint64_t value;
354 int pagemap_fd;
355
356 if (uffd_register(uffd, area_dst, nr_pages * page_size,
357 false, true, false))
358 err("register failed");
359
360 pagemap_fd = pagemap_open();
361
362 /* Test applying pte marker to anon unpopulated */
363 wp_range(uffd, (uint64_t)area_dst, page_size, true);
364 value = pagemap_get_entry(pagemap_fd, area_dst);
365 pagemap_check_wp(value, true);
366
367 /* Test unprotect on anon pte marker */
368 wp_range(uffd, (uint64_t)area_dst, page_size, false);
369 value = pagemap_get_entry(pagemap_fd, area_dst);
370 pagemap_check_wp(value, false);
371
372 /* Test zap on anon marker */
373 wp_range(uffd, (uint64_t)area_dst, page_size, true);
374 if (madvise(area_dst, page_size, MADV_DONTNEED))
375 err("madvise(MADV_DONTNEED) failed");
376 value = pagemap_get_entry(pagemap_fd, area_dst);
377 pagemap_check_wp(value, false);
378
379 /* Test fault in after marker removed */
380 *area_dst = 1;
381 value = pagemap_get_entry(pagemap_fd, area_dst);
382 pagemap_check_wp(value, false);
383 /* Drop it to make pte none again */
384 if (madvise(area_dst, page_size, MADV_DONTNEED))
385 err("madvise(MADV_DONTNEED) failed");
386
387 /* Test read-zero-page upon pte marker */
388 wp_range(uffd, (uint64_t)area_dst, page_size, true);
389 *(volatile char *)area_dst;
390 /* Drop it to make pte none again */
391 if (madvise(area_dst, page_size, MADV_DONTNEED))
392 err("madvise(MADV_DONTNEED) failed");
393
394 uffd_test_pass();
395 }
396
uffd_wp_fork_test_common(uffd_test_args_t * args,bool with_event)397 static void uffd_wp_fork_test_common(uffd_test_args_t *args,
398 bool with_event)
399 {
400 int pagemap_fd;
401 uint64_t value;
402
403 if (uffd_register(uffd, area_dst, nr_pages * page_size,
404 false, true, false))
405 err("register failed");
406
407 pagemap_fd = pagemap_open();
408
409 /* Touch the page */
410 *area_dst = 1;
411 wp_range(uffd, (uint64_t)area_dst, page_size, true);
412 value = pagemap_get_entry(pagemap_fd, area_dst);
413 pagemap_check_wp(value, true);
414 if (pagemap_test_fork(uffd, with_event, false)) {
415 uffd_test_fail("Detected %s uffd-wp bit in child in present pte",
416 with_event ? "missing" : "stall");
417 goto out;
418 }
419
420 /*
421 * This is an attempt for zapping the pgtable so as to test the
422 * markers.
423 *
424 * For private mappings, PAGEOUT will only work on exclusive ptes
425 * (PM_MMAP_EXCLUSIVE) which we should satisfy.
426 *
427 * For shared, PAGEOUT may not work. Use DONTNEED instead which
428 * plays a similar role of zapping (rather than freeing the page)
429 * to expose pte markers.
430 */
431 if (args->mem_type->shared) {
432 if (madvise(area_dst, page_size, MADV_DONTNEED))
433 err("MADV_DONTNEED");
434 } else {
435 /*
436 * NOTE: ignore retval because private-hugetlb doesn't yet
437 * support swapping, so it could fail.
438 */
439 madvise(area_dst, page_size, MADV_PAGEOUT);
440 }
441
442 /* Uffd-wp should persist even swapped out */
443 value = pagemap_get_entry(pagemap_fd, area_dst);
444 pagemap_check_wp(value, true);
445 if (pagemap_test_fork(uffd, with_event, false)) {
446 uffd_test_fail("Detected %s uffd-wp bit in child in zapped pte",
447 with_event ? "missing" : "stall");
448 goto out;
449 }
450
451 /* Unprotect; this tests swap pte modifications */
452 wp_range(uffd, (uint64_t)area_dst, page_size, false);
453 value = pagemap_get_entry(pagemap_fd, area_dst);
454 pagemap_check_wp(value, false);
455
456 /* Fault in the page from disk */
457 *area_dst = 2;
458 value = pagemap_get_entry(pagemap_fd, area_dst);
459 pagemap_check_wp(value, false);
460 uffd_test_pass();
461 out:
462 if (uffd_unregister(uffd, area_dst, nr_pages * page_size))
463 err("unregister failed");
464 close(pagemap_fd);
465 }
466
uffd_wp_fork_test(uffd_test_args_t * args)467 static void uffd_wp_fork_test(uffd_test_args_t *args)
468 {
469 uffd_wp_fork_test_common(args, false);
470 }
471
uffd_wp_fork_with_event_test(uffd_test_args_t * args)472 static void uffd_wp_fork_with_event_test(uffd_test_args_t *args)
473 {
474 uffd_wp_fork_test_common(args, true);
475 }
476
uffd_wp_fork_pin_test_common(uffd_test_args_t * args,bool with_event)477 static void uffd_wp_fork_pin_test_common(uffd_test_args_t *args,
478 bool with_event)
479 {
480 int pagemap_fd;
481 pin_args pin_args = {};
482
483 if (uffd_register(uffd, area_dst, page_size, false, true, false))
484 err("register failed");
485
486 pagemap_fd = pagemap_open();
487
488 /* Touch the page */
489 *area_dst = 1;
490 wp_range(uffd, (uint64_t)area_dst, page_size, true);
491
492 /*
493 * 1. First pin, then fork(). This tests fork() special path when
494 * doing early CoW if the page is private.
495 */
496 if (pin_pages(&pin_args, area_dst, page_size)) {
497 uffd_test_skip("Possibly CONFIG_GUP_TEST missing "
498 "or unprivileged");
499 close(pagemap_fd);
500 uffd_unregister(uffd, area_dst, page_size);
501 return;
502 }
503
504 if (pagemap_test_fork(uffd, with_event, false)) {
505 uffd_test_fail("Detected %s uffd-wp bit in early CoW of fork()",
506 with_event ? "missing" : "stall");
507 unpin_pages(&pin_args);
508 goto out;
509 }
510
511 unpin_pages(&pin_args);
512
513 /*
514 * 2. First fork(), then pin (in the child, where test_pin==true).
515 * This tests COR, aka, page unsharing on private memories.
516 */
517 if (pagemap_test_fork(uffd, with_event, true)) {
518 uffd_test_fail("Detected %s uffd-wp bit when RO pin",
519 with_event ? "missing" : "stall");
520 goto out;
521 }
522 uffd_test_pass();
523 out:
524 if (uffd_unregister(uffd, area_dst, page_size))
525 err("register failed");
526 close(pagemap_fd);
527 }
528
uffd_wp_fork_pin_test(uffd_test_args_t * args)529 static void uffd_wp_fork_pin_test(uffd_test_args_t *args)
530 {
531 uffd_wp_fork_pin_test_common(args, false);
532 }
533
uffd_wp_fork_pin_with_event_test(uffd_test_args_t * args)534 static void uffd_wp_fork_pin_with_event_test(uffd_test_args_t *args)
535 {
536 uffd_wp_fork_pin_test_common(args, true);
537 }
538
check_memory_contents(char * p)539 static void check_memory_contents(char *p)
540 {
541 unsigned long i, j;
542 uint8_t expected_byte;
543
544 for (i = 0; i < nr_pages; ++i) {
545 expected_byte = ~((uint8_t)(i % ((uint8_t)-1)));
546 for (j = 0; j < page_size; j++) {
547 uint8_t v = *(uint8_t *)(p + (i * page_size) + j);
548 if (v != expected_byte)
549 err("unexpected page contents");
550 }
551 }
552 }
553
uffd_minor_test_common(bool test_collapse,bool test_wp)554 static void uffd_minor_test_common(bool test_collapse, bool test_wp)
555 {
556 unsigned long p;
557 pthread_t uffd_mon;
558 char c;
559 struct uffd_args args = { 0 };
560
561 /*
562 * NOTE: MADV_COLLAPSE is not yet compatible with WP, so testing
563 * both do not make much sense.
564 */
565 assert(!(test_collapse && test_wp));
566
567 if (uffd_register(uffd, area_dst_alias, nr_pages * page_size,
568 /* NOTE! MADV_COLLAPSE may not work with uffd-wp */
569 false, test_wp, true))
570 err("register failure");
571
572 /*
573 * After registering with UFFD, populate the non-UFFD-registered side of
574 * the shared mapping. This should *not* trigger any UFFD minor faults.
575 */
576 for (p = 0; p < nr_pages; ++p)
577 memset(area_dst + (p * page_size), p % ((uint8_t)-1),
578 page_size);
579
580 args.apply_wp = test_wp;
581 if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
582 err("uffd_poll_thread create");
583
584 /*
585 * Read each of the pages back using the UFFD-registered mapping. We
586 * expect that the first time we touch a page, it will result in a minor
587 * fault. uffd_poll_thread will resolve the fault by bit-flipping the
588 * page's contents, and then issuing a CONTINUE ioctl.
589 */
590 check_memory_contents(area_dst_alias);
591
592 if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
593 err("pipe write");
594 if (pthread_join(uffd_mon, NULL))
595 err("join() failed");
596
597 if (test_collapse) {
598 if (madvise(area_dst_alias, nr_pages * page_size,
599 MADV_COLLAPSE)) {
600 /* It's fine to fail for this one... */
601 uffd_test_skip("MADV_COLLAPSE failed");
602 return;
603 }
604
605 uffd_test_ops->check_pmd_mapping(area_dst,
606 nr_pages * page_size /
607 read_pmd_pagesize());
608 /*
609 * This won't cause uffd-fault - it purely just makes sure there
610 * was no corruption.
611 */
612 check_memory_contents(area_dst_alias);
613 }
614
615 if (args.missing_faults != 0 || args.minor_faults != nr_pages)
616 uffd_test_fail("stats check error");
617 else
618 uffd_test_pass();
619 }
620
uffd_minor_test(uffd_test_args_t * args)621 void uffd_minor_test(uffd_test_args_t *args)
622 {
623 uffd_minor_test_common(false, false);
624 }
625
uffd_minor_wp_test(uffd_test_args_t * args)626 void uffd_minor_wp_test(uffd_test_args_t *args)
627 {
628 uffd_minor_test_common(false, true);
629 }
630
uffd_minor_collapse_test(uffd_test_args_t * args)631 void uffd_minor_collapse_test(uffd_test_args_t *args)
632 {
633 uffd_minor_test_common(true, false);
634 }
635
636 static sigjmp_buf jbuf, *sigbuf;
637
sighndl(int sig,siginfo_t * siginfo,void * ptr)638 static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
639 {
640 if (sig == SIGBUS) {
641 if (sigbuf)
642 siglongjmp(*sigbuf, 1);
643 abort();
644 }
645 }
646
647 /*
648 * For non-cooperative userfaultfd test we fork() a process that will
649 * generate pagefaults, will mremap the area monitored by the
650 * userfaultfd and at last this process will release the monitored
651 * area.
652 * For the anonymous and shared memory the area is divided into two
653 * parts, the first part is accessed before mremap, and the second
654 * part is accessed after mremap. Since hugetlbfs does not support
655 * mremap, the entire monitored area is accessed in a single pass for
656 * HUGETLB_TEST.
657 * The release of the pages currently generates event for shmem and
658 * anonymous memory (UFFD_EVENT_REMOVE), hence it is not checked
659 * for hugetlb.
660 * For signal test(UFFD_FEATURE_SIGBUS), signal_test = 1, we register
661 * monitored area, generate pagefaults and test that signal is delivered.
662 * Use UFFDIO_COPY to allocate missing page and retry. For signal_test = 2
663 * test robustness use case - we release monitored area, fork a process
664 * that will generate pagefaults and verify signal is generated.
665 * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
666 * feature. Using monitor thread, verify no userfault events are generated.
667 */
faulting_process(int signal_test,bool wp)668 static int faulting_process(int signal_test, bool wp)
669 {
670 unsigned long nr, i;
671 unsigned long long count;
672 unsigned long split_nr_pages;
673 unsigned long lastnr;
674 struct sigaction act;
675 volatile unsigned long signalled = 0;
676
677 split_nr_pages = (nr_pages + 1) / 2;
678
679 if (signal_test) {
680 sigbuf = &jbuf;
681 memset(&act, 0, sizeof(act));
682 act.sa_sigaction = sighndl;
683 act.sa_flags = SA_SIGINFO;
684 if (sigaction(SIGBUS, &act, 0))
685 err("sigaction");
686 lastnr = (unsigned long)-1;
687 }
688
689 for (nr = 0; nr < split_nr_pages; nr++) {
690 volatile int steps = 1;
691 unsigned long offset = nr * page_size;
692
693 if (signal_test) {
694 if (sigsetjmp(*sigbuf, 1) != 0) {
695 if (steps == 1 && nr == lastnr)
696 err("Signal repeated");
697
698 lastnr = nr;
699 if (signal_test == 1) {
700 if (steps == 1) {
701 /* This is a MISSING request */
702 steps++;
703 if (copy_page(uffd, offset, wp))
704 signalled++;
705 } else {
706 /* This is a WP request */
707 assert(steps == 2);
708 wp_range(uffd,
709 (__u64)area_dst +
710 offset,
711 page_size, false);
712 }
713 } else {
714 signalled++;
715 continue;
716 }
717 }
718 }
719
720 count = *area_count(area_dst, nr);
721 if (count != count_verify[nr])
722 err("nr %lu memory corruption %llu %llu\n",
723 nr, count, count_verify[nr]);
724 /*
725 * Trigger write protection if there is by writing
726 * the same value back.
727 */
728 *area_count(area_dst, nr) = count;
729 }
730
731 if (signal_test)
732 return signalled != split_nr_pages;
733
734 area_dst = mremap(area_dst, nr_pages * page_size, nr_pages * page_size,
735 MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
736 if (area_dst == MAP_FAILED)
737 err("mremap");
738 /* Reset area_src since we just clobbered it */
739 area_src = NULL;
740
741 for (; nr < nr_pages; nr++) {
742 count = *area_count(area_dst, nr);
743 if (count != count_verify[nr]) {
744 err("nr %lu memory corruption %llu %llu\n",
745 nr, count, count_verify[nr]);
746 }
747 /*
748 * Trigger write protection if there is by writing
749 * the same value back.
750 */
751 *area_count(area_dst, nr) = count;
752 }
753
754 uffd_test_ops->release_pages(area_dst);
755
756 for (nr = 0; nr < nr_pages; nr++)
757 for (i = 0; i < page_size; i++)
758 if (*(area_dst + nr * page_size + i) != 0)
759 err("page %lu offset %lu is not zero", nr, i);
760
761 return 0;
762 }
763
uffd_sigbus_test_common(bool wp)764 static void uffd_sigbus_test_common(bool wp)
765 {
766 unsigned long userfaults;
767 pthread_t uffd_mon;
768 pid_t pid;
769 int err;
770 char c;
771 struct uffd_args args = { 0 };
772
773 fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
774
775 if (uffd_register(uffd, area_dst, nr_pages * page_size,
776 true, wp, false))
777 err("register failure");
778
779 if (faulting_process(1, wp))
780 err("faulting process failed");
781
782 uffd_test_ops->release_pages(area_dst);
783
784 args.apply_wp = wp;
785 if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
786 err("uffd_poll_thread create");
787
788 pid = fork();
789 if (pid < 0)
790 err("fork");
791
792 if (!pid)
793 exit(faulting_process(2, wp));
794
795 waitpid(pid, &err, 0);
796 if (err)
797 err("faulting process failed");
798 if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
799 err("pipe write");
800 if (pthread_join(uffd_mon, (void **)&userfaults))
801 err("pthread_join()");
802
803 if (userfaults)
804 uffd_test_fail("Signal test failed, userfaults: %ld", userfaults);
805 else
806 uffd_test_pass();
807 }
808
uffd_sigbus_test(uffd_test_args_t * args)809 static void uffd_sigbus_test(uffd_test_args_t *args)
810 {
811 uffd_sigbus_test_common(false);
812 }
813
uffd_sigbus_wp_test(uffd_test_args_t * args)814 static void uffd_sigbus_wp_test(uffd_test_args_t *args)
815 {
816 uffd_sigbus_test_common(true);
817 }
818
uffd_events_test_common(bool wp)819 static void uffd_events_test_common(bool wp)
820 {
821 pthread_t uffd_mon;
822 pid_t pid;
823 int err;
824 char c;
825 struct uffd_args args = { 0 };
826
827 fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
828 if (uffd_register(uffd, area_dst, nr_pages * page_size,
829 true, wp, false))
830 err("register failure");
831
832 args.apply_wp = wp;
833 if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
834 err("uffd_poll_thread create");
835
836 pid = fork();
837 if (pid < 0)
838 err("fork");
839
840 if (!pid)
841 exit(faulting_process(0, wp));
842
843 waitpid(pid, &err, 0);
844 if (err)
845 err("faulting process failed");
846 if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
847 err("pipe write");
848 if (pthread_join(uffd_mon, NULL))
849 err("pthread_join()");
850
851 if (args.missing_faults != nr_pages)
852 uffd_test_fail("Fault counts wrong");
853 else
854 uffd_test_pass();
855 }
856
uffd_events_test(uffd_test_args_t * args)857 static void uffd_events_test(uffd_test_args_t *args)
858 {
859 uffd_events_test_common(false);
860 }
861
uffd_events_wp_test(uffd_test_args_t * args)862 static void uffd_events_wp_test(uffd_test_args_t *args)
863 {
864 uffd_events_test_common(true);
865 }
866
retry_uffdio_zeropage(int ufd,struct uffdio_zeropage * uffdio_zeropage)867 static void retry_uffdio_zeropage(int ufd,
868 struct uffdio_zeropage *uffdio_zeropage)
869 {
870 uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
871 uffdio_zeropage->range.len,
872 0);
873 if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
874 if (uffdio_zeropage->zeropage != -EEXIST)
875 err("UFFDIO_ZEROPAGE error: %"PRId64,
876 (int64_t)uffdio_zeropage->zeropage);
877 } else {
878 err("UFFDIO_ZEROPAGE error: %"PRId64,
879 (int64_t)uffdio_zeropage->zeropage);
880 }
881 }
882
do_uffdio_zeropage(int ufd,bool has_zeropage)883 static bool do_uffdio_zeropage(int ufd, bool has_zeropage)
884 {
885 struct uffdio_zeropage uffdio_zeropage = { 0 };
886 int ret;
887 __s64 res;
888
889 uffdio_zeropage.range.start = (unsigned long) area_dst;
890 uffdio_zeropage.range.len = page_size;
891 uffdio_zeropage.mode = 0;
892 ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
893 res = uffdio_zeropage.zeropage;
894 if (ret) {
895 /* real retval in ufdio_zeropage.zeropage */
896 if (has_zeropage)
897 err("UFFDIO_ZEROPAGE error: %"PRId64, (int64_t)res);
898 else if (res != -EINVAL)
899 err("UFFDIO_ZEROPAGE not -EINVAL");
900 } else if (has_zeropage) {
901 if (res != page_size)
902 err("UFFDIO_ZEROPAGE unexpected size");
903 else
904 retry_uffdio_zeropage(ufd, &uffdio_zeropage);
905 return true;
906 } else
907 err("UFFDIO_ZEROPAGE succeeded");
908
909 return false;
910 }
911
912 /*
913 * Registers a range with MISSING mode only for zeropage test. Return true
914 * if UFFDIO_ZEROPAGE supported, false otherwise. Can't use uffd_register()
915 * because we want to detect .ioctls along the way.
916 */
917 static bool
uffd_register_detect_zeropage(int uffd,void * addr,uint64_t len)918 uffd_register_detect_zeropage(int uffd, void *addr, uint64_t len)
919 {
920 uint64_t ioctls = 0;
921
922 if (uffd_register_with_ioctls(uffd, addr, len, true,
923 false, false, &ioctls))
924 err("zeropage register fail");
925
926 return ioctls & (1 << _UFFDIO_ZEROPAGE);
927 }
928
929 /* exercise UFFDIO_ZEROPAGE */
uffd_zeropage_test(uffd_test_args_t * args)930 static void uffd_zeropage_test(uffd_test_args_t *args)
931 {
932 bool has_zeropage;
933 int i;
934
935 has_zeropage = uffd_register_detect_zeropage(uffd, area_dst, page_size);
936 if (area_dst_alias)
937 /* Ignore the retval; we already have it */
938 uffd_register_detect_zeropage(uffd, area_dst_alias, page_size);
939
940 if (do_uffdio_zeropage(uffd, has_zeropage))
941 for (i = 0; i < page_size; i++)
942 if (area_dst[i] != 0)
943 err("data non-zero at offset %d\n", i);
944
945 if (uffd_unregister(uffd, area_dst, page_size))
946 err("unregister");
947
948 if (area_dst_alias && uffd_unregister(uffd, area_dst_alias, page_size))
949 err("unregister");
950
951 uffd_test_pass();
952 }
953
uffd_register_poison(int uffd,void * addr,uint64_t len)954 static void uffd_register_poison(int uffd, void *addr, uint64_t len)
955 {
956 uint64_t ioctls = 0;
957 uint64_t expected = (1 << _UFFDIO_COPY) | (1 << _UFFDIO_POISON);
958
959 if (uffd_register_with_ioctls(uffd, addr, len, true,
960 false, false, &ioctls))
961 err("poison register fail");
962
963 if ((ioctls & expected) != expected)
964 err("registered area doesn't support COPY and POISON ioctls");
965 }
966
do_uffdio_poison(int uffd,unsigned long offset)967 static void do_uffdio_poison(int uffd, unsigned long offset)
968 {
969 struct uffdio_poison uffdio_poison = { 0 };
970 int ret;
971 __s64 res;
972
973 uffdio_poison.range.start = (unsigned long) area_dst + offset;
974 uffdio_poison.range.len = page_size;
975 uffdio_poison.mode = 0;
976 ret = ioctl(uffd, UFFDIO_POISON, &uffdio_poison);
977 res = uffdio_poison.updated;
978
979 if (ret)
980 err("UFFDIO_POISON error: %"PRId64, (int64_t)res);
981 else if (res != page_size)
982 err("UFFDIO_POISON unexpected size: %"PRId64, (int64_t)res);
983 }
984
uffd_poison_handle_fault(struct uffd_msg * msg,struct uffd_args * args)985 static void uffd_poison_handle_fault(
986 struct uffd_msg *msg, struct uffd_args *args)
987 {
988 unsigned long offset;
989
990 if (msg->event != UFFD_EVENT_PAGEFAULT)
991 err("unexpected msg event %u", msg->event);
992
993 if (msg->arg.pagefault.flags &
994 (UFFD_PAGEFAULT_FLAG_WP | UFFD_PAGEFAULT_FLAG_MINOR))
995 err("unexpected fault type %llu", msg->arg.pagefault.flags);
996
997 offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
998 offset &= ~(page_size-1);
999
1000 /* Odd pages -> copy zeroed page; even pages -> poison. */
1001 if (offset & page_size)
1002 copy_page(uffd, offset, false);
1003 else
1004 do_uffdio_poison(uffd, offset);
1005 }
1006
uffd_poison_test(uffd_test_args_t * targs)1007 static void uffd_poison_test(uffd_test_args_t *targs)
1008 {
1009 pthread_t uffd_mon;
1010 char c;
1011 struct uffd_args args = { 0 };
1012 struct sigaction act = { 0 };
1013 unsigned long nr_sigbus = 0;
1014 unsigned long nr;
1015
1016 fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
1017
1018 uffd_register_poison(uffd, area_dst, nr_pages * page_size);
1019 memset(area_src, 0, nr_pages * page_size);
1020
1021 args.handle_fault = uffd_poison_handle_fault;
1022 if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
1023 err("uffd_poll_thread create");
1024
1025 sigbuf = &jbuf;
1026 act.sa_sigaction = sighndl;
1027 act.sa_flags = SA_SIGINFO;
1028 if (sigaction(SIGBUS, &act, 0))
1029 err("sigaction");
1030
1031 for (nr = 0; nr < nr_pages; ++nr) {
1032 unsigned long offset = nr * page_size;
1033 const char *bytes = (const char *) area_dst + offset;
1034 const char *i;
1035
1036 if (sigsetjmp(*sigbuf, 1)) {
1037 /*
1038 * Access below triggered a SIGBUS, which was caught by
1039 * sighndl, which then jumped here. Count this SIGBUS,
1040 * and move on to next page.
1041 */
1042 ++nr_sigbus;
1043 continue;
1044 }
1045
1046 for (i = bytes; i < bytes + page_size; ++i) {
1047 if (*i)
1048 err("nonzero byte in area_dst (%p) at %p: %u",
1049 area_dst, i, *i);
1050 }
1051 }
1052
1053 if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
1054 err("pipe write");
1055 if (pthread_join(uffd_mon, NULL))
1056 err("pthread_join()");
1057
1058 if (nr_sigbus != nr_pages / 2)
1059 err("expected to receive %lu SIGBUS, actually received %lu",
1060 nr_pages / 2, nr_sigbus);
1061
1062 uffd_test_pass();
1063 }
1064
1065 /*
1066 * Test the returned uffdio_register.ioctls with different register modes.
1067 * Note that _UFFDIO_ZEROPAGE is tested separately in the zeropage test.
1068 */
1069 static void
do_register_ioctls_test(uffd_test_args_t * args,bool miss,bool wp,bool minor)1070 do_register_ioctls_test(uffd_test_args_t *args, bool miss, bool wp, bool minor)
1071 {
1072 uint64_t ioctls = 0, expected = BIT_ULL(_UFFDIO_WAKE);
1073 mem_type_t *mem_type = args->mem_type;
1074 int ret;
1075
1076 ret = uffd_register_with_ioctls(uffd, area_dst, page_size,
1077 miss, wp, minor, &ioctls);
1078
1079 /*
1080 * Handle special cases of UFFDIO_REGISTER here where it should
1081 * just fail with -EINVAL first..
1082 *
1083 * Case 1: register MINOR on anon
1084 * Case 2: register with no mode selected
1085 */
1086 if ((minor && (mem_type->mem_flag == MEM_ANON)) ||
1087 (!miss && !wp && !minor)) {
1088 if (ret != -EINVAL)
1089 err("register (miss=%d, wp=%d, minor=%d) failed "
1090 "with wrong errno=%d", miss, wp, minor, ret);
1091 return;
1092 }
1093
1094 /* UFFDIO_REGISTER should succeed, then check ioctls returned */
1095 if (miss)
1096 expected |= BIT_ULL(_UFFDIO_COPY);
1097 if (wp)
1098 expected |= BIT_ULL(_UFFDIO_WRITEPROTECT);
1099 if (minor)
1100 expected |= BIT_ULL(_UFFDIO_CONTINUE);
1101
1102 if ((ioctls & expected) != expected)
1103 err("unexpected uffdio_register.ioctls "
1104 "(miss=%d, wp=%d, minor=%d): expected=0x%"PRIx64", "
1105 "returned=0x%"PRIx64, miss, wp, minor, expected, ioctls);
1106
1107 if (uffd_unregister(uffd, area_dst, page_size))
1108 err("unregister");
1109 }
1110
uffd_register_ioctls_test(uffd_test_args_t * args)1111 static void uffd_register_ioctls_test(uffd_test_args_t *args)
1112 {
1113 int miss, wp, minor;
1114
1115 for (miss = 0; miss <= 1; miss++)
1116 for (wp = 0; wp <= 1; wp++)
1117 for (minor = 0; minor <= 1; minor++)
1118 do_register_ioctls_test(args, miss, wp, minor);
1119
1120 uffd_test_pass();
1121 }
1122
1123 uffd_test_case_t uffd_tests[] = {
1124 {
1125 /* Test returned uffdio_register.ioctls. */
1126 .name = "register-ioctls",
1127 .uffd_fn = uffd_register_ioctls_test,
1128 .mem_targets = MEM_ALL,
1129 .uffd_feature_required = UFFD_FEATURE_MISSING_HUGETLBFS |
1130 UFFD_FEATURE_MISSING_SHMEM |
1131 UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1132 UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
1133 UFFD_FEATURE_MINOR_HUGETLBFS |
1134 UFFD_FEATURE_MINOR_SHMEM,
1135 },
1136 {
1137 .name = "zeropage",
1138 .uffd_fn = uffd_zeropage_test,
1139 .mem_targets = MEM_ALL,
1140 .uffd_feature_required = 0,
1141 },
1142 {
1143 .name = "wp-fork",
1144 .uffd_fn = uffd_wp_fork_test,
1145 .mem_targets = MEM_ALL,
1146 .uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1147 UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
1148 },
1149 {
1150 .name = "wp-fork-with-event",
1151 .uffd_fn = uffd_wp_fork_with_event_test,
1152 .mem_targets = MEM_ALL,
1153 .uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1154 UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
1155 /* when set, child process should inherit uffd-wp bits */
1156 UFFD_FEATURE_EVENT_FORK,
1157 },
1158 {
1159 .name = "wp-fork-pin",
1160 .uffd_fn = uffd_wp_fork_pin_test,
1161 .mem_targets = MEM_ALL,
1162 .uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1163 UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
1164 },
1165 {
1166 .name = "wp-fork-pin-with-event",
1167 .uffd_fn = uffd_wp_fork_pin_with_event_test,
1168 .mem_targets = MEM_ALL,
1169 .uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1170 UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
1171 /* when set, child process should inherit uffd-wp bits */
1172 UFFD_FEATURE_EVENT_FORK,
1173 },
1174 {
1175 .name = "wp-unpopulated",
1176 .uffd_fn = uffd_wp_unpopulated_test,
1177 .mem_targets = MEM_ANON,
1178 .uffd_feature_required =
1179 UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_UNPOPULATED,
1180 },
1181 {
1182 .name = "minor",
1183 .uffd_fn = uffd_minor_test,
1184 .mem_targets = MEM_SHMEM | MEM_HUGETLB,
1185 .uffd_feature_required =
1186 UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM,
1187 },
1188 {
1189 .name = "minor-wp",
1190 .uffd_fn = uffd_minor_wp_test,
1191 .mem_targets = MEM_SHMEM | MEM_HUGETLB,
1192 .uffd_feature_required =
1193 UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM |
1194 UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1195 /*
1196 * HACK: here we leveraged WP_UNPOPULATED to detect whether
1197 * minor mode supports wr-protect. There's no feature flag
1198 * for it so this is the best we can test against.
1199 */
1200 UFFD_FEATURE_WP_UNPOPULATED,
1201 },
1202 {
1203 .name = "minor-collapse",
1204 .uffd_fn = uffd_minor_collapse_test,
1205 /* MADV_COLLAPSE only works with shmem */
1206 .mem_targets = MEM_SHMEM,
1207 /* We can't test MADV_COLLAPSE, so try our luck */
1208 .uffd_feature_required = UFFD_FEATURE_MINOR_SHMEM,
1209 },
1210 {
1211 .name = "sigbus",
1212 .uffd_fn = uffd_sigbus_test,
1213 .mem_targets = MEM_ALL,
1214 .uffd_feature_required = UFFD_FEATURE_SIGBUS |
1215 UFFD_FEATURE_EVENT_FORK,
1216 },
1217 {
1218 .name = "sigbus-wp",
1219 .uffd_fn = uffd_sigbus_wp_test,
1220 .mem_targets = MEM_ALL,
1221 .uffd_feature_required = UFFD_FEATURE_SIGBUS |
1222 UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_PAGEFAULT_FLAG_WP,
1223 },
1224 {
1225 .name = "events",
1226 .uffd_fn = uffd_events_test,
1227 .mem_targets = MEM_ALL,
1228 .uffd_feature_required = UFFD_FEATURE_EVENT_FORK |
1229 UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE,
1230 },
1231 {
1232 .name = "events-wp",
1233 .uffd_fn = uffd_events_wp_test,
1234 .mem_targets = MEM_ALL,
1235 .uffd_feature_required = UFFD_FEATURE_EVENT_FORK |
1236 UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE |
1237 UFFD_FEATURE_PAGEFAULT_FLAG_WP |
1238 UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
1239 },
1240 {
1241 .name = "poison",
1242 .uffd_fn = uffd_poison_test,
1243 .mem_targets = MEM_ALL,
1244 .uffd_feature_required = UFFD_FEATURE_POISON,
1245 },
1246 };
1247
usage(const char * prog)1248 static void usage(const char *prog)
1249 {
1250 printf("usage: %s [-f TESTNAME]\n", prog);
1251 puts("");
1252 puts(" -f: test name to filter (e.g., event)");
1253 puts(" -h: show the help msg");
1254 puts(" -l: list tests only");
1255 puts("");
1256 exit(KSFT_FAIL);
1257 }
1258
main(int argc,char * argv[])1259 int main(int argc, char *argv[])
1260 {
1261 int n_tests = sizeof(uffd_tests) / sizeof(uffd_test_case_t);
1262 int n_mems = sizeof(mem_types) / sizeof(mem_type_t);
1263 const char *test_filter = NULL;
1264 bool list_only = false;
1265 uffd_test_case_t *test;
1266 mem_type_t *mem_type;
1267 uffd_test_args_t args;
1268 const char *errmsg;
1269 int has_uffd, opt;
1270 int i, j;
1271
1272 while ((opt = getopt(argc, argv, "f:hl")) != -1) {
1273 switch (opt) {
1274 case 'f':
1275 test_filter = optarg;
1276 break;
1277 case 'l':
1278 list_only = true;
1279 break;
1280 case 'h':
1281 default:
1282 /* Unknown */
1283 usage(argv[0]);
1284 break;
1285 }
1286 }
1287
1288 if (!test_filter && !list_only) {
1289 has_uffd = test_uffd_api(false);
1290 has_uffd |= test_uffd_api(true);
1291
1292 if (!has_uffd) {
1293 printf("Userfaultfd not supported or unprivileged, skip all tests\n");
1294 exit(KSFT_SKIP);
1295 }
1296 }
1297
1298 for (i = 0; i < n_tests; i++) {
1299 test = &uffd_tests[i];
1300 if (test_filter && !strstr(test->name, test_filter))
1301 continue;
1302 if (list_only) {
1303 printf("%s\n", test->name);
1304 continue;
1305 }
1306 for (j = 0; j < n_mems; j++) {
1307 mem_type = &mem_types[j];
1308 if (!(test->mem_targets & mem_type->mem_flag))
1309 continue;
1310
1311 uffd_test_start("%s on %s", test->name, mem_type->name);
1312 if (!uffd_feature_supported(test)) {
1313 uffd_test_skip("feature missing");
1314 continue;
1315 }
1316 if (uffd_setup_environment(&args, test, mem_type,
1317 &errmsg)) {
1318 uffd_test_skip(errmsg);
1319 continue;
1320 }
1321 test->uffd_fn(&args);
1322 }
1323 }
1324
1325 if (!list_only)
1326 uffd_test_report();
1327
1328 return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS;
1329 }
1330
1331 #else /* __NR_userfaultfd */
1332
1333 #warning "missing __NR_userfaultfd definition"
1334
main(void)1335 int main(void)
1336 {
1337 printf("Skipping %s (missing __NR_userfaultfd)\n", __file__);
1338 return KSFT_SKIP;
1339 }
1340
1341 #endif /* __NR_userfaultfd */
1342
