1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3 
4 #define _GNU_SOURCE
5 #include <linux/compiler.h>
6 #include <linux/ring_buffer.h>
7 #include <linux/build_bug.h>
8 #include <pthread.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <sys/mman.h>
12 #include <sys/syscall.h>
13 #include <sys/sysinfo.h>
14 #include <test_progs.h>
15 #include <uapi/linux/bpf.h>
16 #include <unistd.h>
17 
18 #include "user_ringbuf_fail.skel.h"
19 #include "user_ringbuf_success.skel.h"
20 
21 #include "../progs/test_user_ringbuf.h"
22 
23 static const long c_sample_size = sizeof(struct sample) + BPF_RINGBUF_HDR_SZ;
24 static long c_ringbuf_size, c_max_entries;
25 
drain_current_samples(void)26 static void drain_current_samples(void)
27 {
28 	syscall(__NR_getpgid);
29 }
30 
write_samples(struct user_ring_buffer * ringbuf,uint32_t num_samples)31 static int write_samples(struct user_ring_buffer *ringbuf, uint32_t num_samples)
32 {
33 	int i, err = 0;
34 
35 	/* Write some number of samples to the ring buffer. */
36 	for (i = 0; i < num_samples; i++) {
37 		struct sample *entry;
38 		int read;
39 
40 		entry = user_ring_buffer__reserve(ringbuf, sizeof(*entry));
41 		if (!entry) {
42 			err = -errno;
43 			goto done;
44 		}
45 
46 		entry->pid = getpid();
47 		entry->seq = i;
48 		entry->value = i * i;
49 
50 		read = snprintf(entry->comm, sizeof(entry->comm), "%u", i);
51 		if (read <= 0) {
52 			/* Assert on the error path to avoid spamming logs with
53 			 * mostly success messages.
54 			 */
55 			ASSERT_GT(read, 0, "snprintf_comm");
56 			err = read;
57 			user_ring_buffer__discard(ringbuf, entry);
58 			goto done;
59 		}
60 
61 		user_ring_buffer__submit(ringbuf, entry);
62 	}
63 
64 done:
65 	drain_current_samples();
66 
67 	return err;
68 }
69 
open_load_ringbuf_skel(void)70 static struct user_ringbuf_success *open_load_ringbuf_skel(void)
71 {
72 	struct user_ringbuf_success *skel;
73 	int err;
74 
75 	skel = user_ringbuf_success__open();
76 	if (!ASSERT_OK_PTR(skel, "skel_open"))
77 		return NULL;
78 
79 	err = bpf_map__set_max_entries(skel->maps.user_ringbuf, c_ringbuf_size);
80 	if (!ASSERT_OK(err, "set_max_entries"))
81 		goto cleanup;
82 
83 	err = bpf_map__set_max_entries(skel->maps.kernel_ringbuf, c_ringbuf_size);
84 	if (!ASSERT_OK(err, "set_max_entries"))
85 		goto cleanup;
86 
87 	err = user_ringbuf_success__load(skel);
88 	if (!ASSERT_OK(err, "skel_load"))
89 		goto cleanup;
90 
91 	return skel;
92 
93 cleanup:
94 	user_ringbuf_success__destroy(skel);
95 	return NULL;
96 }
97 
test_user_ringbuf_mappings(void)98 static void test_user_ringbuf_mappings(void)
99 {
100 	int err, rb_fd;
101 	int page_size = getpagesize();
102 	void *mmap_ptr;
103 	struct user_ringbuf_success *skel;
104 
105 	skel = open_load_ringbuf_skel();
106 	if (!skel)
107 		return;
108 
109 	rb_fd = bpf_map__fd(skel->maps.user_ringbuf);
110 	/* cons_pos can be mapped R/O, can't add +X with mprotect. */
111 	mmap_ptr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, rb_fd, 0);
112 	ASSERT_OK_PTR(mmap_ptr, "ro_cons_pos");
113 	ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_WRITE), "write_cons_pos_protect");
114 	ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_cons_pos_protect");
115 	ASSERT_ERR_PTR(mremap(mmap_ptr, 0, 4 * page_size, MREMAP_MAYMOVE), "wr_prod_pos");
116 	err = -errno;
117 	ASSERT_ERR(err, "wr_prod_pos_err");
118 	ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_ro_cons");
119 
120 	/* prod_pos can be mapped RW, can't add +X with mprotect. */
121 	mmap_ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED,
122 			rb_fd, page_size);
123 	ASSERT_OK_PTR(mmap_ptr, "rw_prod_pos");
124 	ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_prod_pos_protect");
125 	err = -errno;
126 	ASSERT_ERR(err, "wr_prod_pos_err");
127 	ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_rw_prod");
128 
129 	/* data pages can be mapped RW, can't add +X with mprotect. */
130 	mmap_ptr = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, rb_fd,
131 			2 * page_size);
132 	ASSERT_OK_PTR(mmap_ptr, "rw_data");
133 	ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_data_protect");
134 	err = -errno;
135 	ASSERT_ERR(err, "exec_data_err");
136 	ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_rw_data");
137 
138 	user_ringbuf_success__destroy(skel);
139 }
140 
load_skel_create_ringbufs(struct user_ringbuf_success ** skel_out,struct ring_buffer ** kern_ringbuf_out,ring_buffer_sample_fn callback,struct user_ring_buffer ** user_ringbuf_out)141 static int load_skel_create_ringbufs(struct user_ringbuf_success **skel_out,
142 				     struct ring_buffer **kern_ringbuf_out,
143 				     ring_buffer_sample_fn callback,
144 				     struct user_ring_buffer **user_ringbuf_out)
145 {
146 	struct user_ringbuf_success *skel;
147 	struct ring_buffer *kern_ringbuf = NULL;
148 	struct user_ring_buffer *user_ringbuf = NULL;
149 	int err = -ENOMEM, rb_fd;
150 
151 	skel = open_load_ringbuf_skel();
152 	if (!skel)
153 		return err;
154 
155 	/* only trigger BPF program for current process */
156 	skel->bss->pid = getpid();
157 
158 	if (kern_ringbuf_out) {
159 		rb_fd = bpf_map__fd(skel->maps.kernel_ringbuf);
160 		kern_ringbuf = ring_buffer__new(rb_fd, callback, skel, NULL);
161 		if (!ASSERT_OK_PTR(kern_ringbuf, "kern_ringbuf_create"))
162 			goto cleanup;
163 
164 		*kern_ringbuf_out = kern_ringbuf;
165 	}
166 
167 	if (user_ringbuf_out) {
168 		rb_fd = bpf_map__fd(skel->maps.user_ringbuf);
169 		user_ringbuf = user_ring_buffer__new(rb_fd, NULL);
170 		if (!ASSERT_OK_PTR(user_ringbuf, "user_ringbuf_create"))
171 			goto cleanup;
172 
173 		*user_ringbuf_out = user_ringbuf;
174 		ASSERT_EQ(skel->bss->read, 0, "no_reads_after_load");
175 	}
176 
177 	err = user_ringbuf_success__attach(skel);
178 	if (!ASSERT_OK(err, "skel_attach"))
179 		goto cleanup;
180 
181 	*skel_out = skel;
182 	return 0;
183 
184 cleanup:
185 	if (kern_ringbuf_out)
186 		*kern_ringbuf_out = NULL;
187 	if (user_ringbuf_out)
188 		*user_ringbuf_out = NULL;
189 	ring_buffer__free(kern_ringbuf);
190 	user_ring_buffer__free(user_ringbuf);
191 	user_ringbuf_success__destroy(skel);
192 	return err;
193 }
194 
load_skel_create_user_ringbuf(struct user_ringbuf_success ** skel_out,struct user_ring_buffer ** ringbuf_out)195 static int load_skel_create_user_ringbuf(struct user_ringbuf_success **skel_out,
196 					 struct user_ring_buffer **ringbuf_out)
197 {
198 	return load_skel_create_ringbufs(skel_out, NULL, NULL, ringbuf_out);
199 }
200 
manually_write_test_invalid_sample(struct user_ringbuf_success * skel,__u32 size,__u64 producer_pos,int err)201 static void manually_write_test_invalid_sample(struct user_ringbuf_success *skel,
202 					       __u32 size, __u64 producer_pos, int err)
203 {
204 	void *data_ptr;
205 	__u64 *producer_pos_ptr;
206 	int rb_fd, page_size = getpagesize();
207 
208 	rb_fd = bpf_map__fd(skel->maps.user_ringbuf);
209 
210 	ASSERT_EQ(skel->bss->read, 0, "num_samples_before_bad_sample");
211 
212 	/* Map the producer_pos as RW. */
213 	producer_pos_ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
214 				MAP_SHARED, rb_fd, page_size);
215 	ASSERT_OK_PTR(producer_pos_ptr, "producer_pos_ptr");
216 
217 	/* Map the data pages as RW. */
218 	data_ptr = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, rb_fd, 2 * page_size);
219 	ASSERT_OK_PTR(data_ptr, "rw_data");
220 
221 	memset(data_ptr, 0, BPF_RINGBUF_HDR_SZ);
222 	*(__u32 *)data_ptr = size;
223 
224 	/* Synchronizes with smp_load_acquire() in __bpf_user_ringbuf_peek() in the kernel. */
225 	smp_store_release(producer_pos_ptr, producer_pos + BPF_RINGBUF_HDR_SZ);
226 
227 	drain_current_samples();
228 	ASSERT_EQ(skel->bss->read, 0, "num_samples_after_bad_sample");
229 	ASSERT_EQ(skel->bss->err, err, "err_after_bad_sample");
230 
231 	ASSERT_OK(munmap(producer_pos_ptr, page_size), "unmap_producer_pos");
232 	ASSERT_OK(munmap(data_ptr, page_size), "unmap_data_ptr");
233 }
234 
test_user_ringbuf_post_misaligned(void)235 static void test_user_ringbuf_post_misaligned(void)
236 {
237 	struct user_ringbuf_success *skel;
238 	struct user_ring_buffer *ringbuf;
239 	int err;
240 	__u32 size = (1 << 5) + 7;
241 
242 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
243 	if (!ASSERT_OK(err, "misaligned_skel"))
244 		return;
245 
246 	manually_write_test_invalid_sample(skel, size, size, -EINVAL);
247 	user_ring_buffer__free(ringbuf);
248 	user_ringbuf_success__destroy(skel);
249 }
250 
test_user_ringbuf_post_producer_wrong_offset(void)251 static void test_user_ringbuf_post_producer_wrong_offset(void)
252 {
253 	struct user_ringbuf_success *skel;
254 	struct user_ring_buffer *ringbuf;
255 	int err;
256 	__u32 size = (1 << 5);
257 
258 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
259 	if (!ASSERT_OK(err, "wrong_offset_skel"))
260 		return;
261 
262 	manually_write_test_invalid_sample(skel, size, size - 8, -EINVAL);
263 	user_ring_buffer__free(ringbuf);
264 	user_ringbuf_success__destroy(skel);
265 }
266 
test_user_ringbuf_post_larger_than_ringbuf_sz(void)267 static void test_user_ringbuf_post_larger_than_ringbuf_sz(void)
268 {
269 	struct user_ringbuf_success *skel;
270 	struct user_ring_buffer *ringbuf;
271 	int err;
272 	__u32 size = c_ringbuf_size;
273 
274 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
275 	if (!ASSERT_OK(err, "huge_sample_skel"))
276 		return;
277 
278 	manually_write_test_invalid_sample(skel, size, size, -E2BIG);
279 	user_ring_buffer__free(ringbuf);
280 	user_ringbuf_success__destroy(skel);
281 }
282 
test_user_ringbuf_basic(void)283 static void test_user_ringbuf_basic(void)
284 {
285 	struct user_ringbuf_success *skel;
286 	struct user_ring_buffer *ringbuf;
287 	int err;
288 
289 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
290 	if (!ASSERT_OK(err, "ringbuf_basic_skel"))
291 		return;
292 
293 	ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
294 
295 	err = write_samples(ringbuf, 2);
296 	if (!ASSERT_OK(err, "write_samples"))
297 		goto cleanup;
298 
299 	ASSERT_EQ(skel->bss->read, 2, "num_samples_read_after");
300 
301 cleanup:
302 	user_ring_buffer__free(ringbuf);
303 	user_ringbuf_success__destroy(skel);
304 }
305 
test_user_ringbuf_sample_full_ring_buffer(void)306 static void test_user_ringbuf_sample_full_ring_buffer(void)
307 {
308 	struct user_ringbuf_success *skel;
309 	struct user_ring_buffer *ringbuf;
310 	int err;
311 	void *sample;
312 
313 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
314 	if (!ASSERT_OK(err, "ringbuf_full_sample_skel"))
315 		return;
316 
317 	sample = user_ring_buffer__reserve(ringbuf, c_ringbuf_size - BPF_RINGBUF_HDR_SZ);
318 	if (!ASSERT_OK_PTR(sample, "full_sample"))
319 		goto cleanup;
320 
321 	user_ring_buffer__submit(ringbuf, sample);
322 	ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
323 	drain_current_samples();
324 	ASSERT_EQ(skel->bss->read, 1, "num_samples_read_after");
325 
326 cleanup:
327 	user_ring_buffer__free(ringbuf);
328 	user_ringbuf_success__destroy(skel);
329 }
330 
test_user_ringbuf_post_alignment_autoadjust(void)331 static void test_user_ringbuf_post_alignment_autoadjust(void)
332 {
333 	struct user_ringbuf_success *skel;
334 	struct user_ring_buffer *ringbuf;
335 	struct sample *sample;
336 	int err;
337 
338 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
339 	if (!ASSERT_OK(err, "ringbuf_align_autoadjust_skel"))
340 		return;
341 
342 	/* libbpf should automatically round any sample up to an 8-byte alignment. */
343 	sample = user_ring_buffer__reserve(ringbuf, sizeof(*sample) + 1);
344 	ASSERT_OK_PTR(sample, "reserve_autoaligned");
345 	user_ring_buffer__submit(ringbuf, sample);
346 
347 	ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
348 	drain_current_samples();
349 	ASSERT_EQ(skel->bss->read, 1, "num_samples_read_after");
350 
351 	user_ring_buffer__free(ringbuf);
352 	user_ringbuf_success__destroy(skel);
353 }
354 
test_user_ringbuf_overfill(void)355 static void test_user_ringbuf_overfill(void)
356 {
357 	struct user_ringbuf_success *skel;
358 	struct user_ring_buffer *ringbuf;
359 	int err;
360 
361 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
362 	if (err)
363 		return;
364 
365 	err = write_samples(ringbuf, c_max_entries * 5);
366 	ASSERT_ERR(err, "write_samples");
367 	ASSERT_EQ(skel->bss->read, c_max_entries, "max_entries");
368 
369 	user_ring_buffer__free(ringbuf);
370 	user_ringbuf_success__destroy(skel);
371 }
372 
test_user_ringbuf_discards_properly_ignored(void)373 static void test_user_ringbuf_discards_properly_ignored(void)
374 {
375 	struct user_ringbuf_success *skel;
376 	struct user_ring_buffer *ringbuf;
377 	int err, num_discarded = 0;
378 	__u64 *token;
379 
380 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
381 	if (err)
382 		return;
383 
384 	ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
385 
386 	while (1) {
387 		/* Write samples until the buffer is full. */
388 		token = user_ring_buffer__reserve(ringbuf, sizeof(*token));
389 		if (!token)
390 			break;
391 
392 		user_ring_buffer__discard(ringbuf, token);
393 		num_discarded++;
394 	}
395 
396 	if (!ASSERT_GE(num_discarded, 0, "num_discarded"))
397 		goto cleanup;
398 
399 	/* Should not read any samples, as they are all discarded. */
400 	ASSERT_EQ(skel->bss->read, 0, "num_pre_kick");
401 	drain_current_samples();
402 	ASSERT_EQ(skel->bss->read, 0, "num_post_kick");
403 
404 	/* Now that the ring buffer has been drained, we should be able to
405 	 * reserve another token.
406 	 */
407 	token = user_ring_buffer__reserve(ringbuf, sizeof(*token));
408 
409 	if (!ASSERT_OK_PTR(token, "new_token"))
410 		goto cleanup;
411 
412 	user_ring_buffer__discard(ringbuf, token);
413 cleanup:
414 	user_ring_buffer__free(ringbuf);
415 	user_ringbuf_success__destroy(skel);
416 }
417 
test_user_ringbuf_loop(void)418 static void test_user_ringbuf_loop(void)
419 {
420 	struct user_ringbuf_success *skel;
421 	struct user_ring_buffer *ringbuf;
422 	uint32_t total_samples = 8192;
423 	uint32_t remaining_samples = total_samples;
424 	int err;
425 
426 	if (!ASSERT_LT(c_max_entries, total_samples, "compare_c_max_entries"))
427 		return;
428 
429 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
430 	if (err)
431 		return;
432 
433 	do  {
434 		uint32_t curr_samples;
435 
436 		curr_samples = remaining_samples > c_max_entries
437 			? c_max_entries : remaining_samples;
438 		err = write_samples(ringbuf, curr_samples);
439 		if (err != 0) {
440 			/* Assert inside of if statement to avoid flooding logs
441 			 * on the success path.
442 			 */
443 			ASSERT_OK(err, "write_samples");
444 			goto cleanup;
445 		}
446 
447 		remaining_samples -= curr_samples;
448 		ASSERT_EQ(skel->bss->read, total_samples - remaining_samples,
449 			  "current_batched_entries");
450 	} while (remaining_samples > 0);
451 	ASSERT_EQ(skel->bss->read, total_samples, "total_batched_entries");
452 
453 cleanup:
454 	user_ring_buffer__free(ringbuf);
455 	user_ringbuf_success__destroy(skel);
456 }
457 
send_test_message(struct user_ring_buffer * ringbuf,enum test_msg_op op,s64 operand_64,s32 operand_32)458 static int send_test_message(struct user_ring_buffer *ringbuf,
459 			     enum test_msg_op op, s64 operand_64,
460 			     s32 operand_32)
461 {
462 	struct test_msg *msg;
463 
464 	msg = user_ring_buffer__reserve(ringbuf, sizeof(*msg));
465 	if (!msg) {
466 		/* Assert on the error path to avoid spamming logs with mostly
467 		 * success messages.
468 		 */
469 		ASSERT_OK_PTR(msg, "reserve_msg");
470 		return -ENOMEM;
471 	}
472 
473 	msg->msg_op = op;
474 
475 	switch (op) {
476 	case TEST_MSG_OP_INC64:
477 	case TEST_MSG_OP_MUL64:
478 		msg->operand_64 = operand_64;
479 		break;
480 	case TEST_MSG_OP_INC32:
481 	case TEST_MSG_OP_MUL32:
482 		msg->operand_32 = operand_32;
483 		break;
484 	default:
485 		PRINT_FAIL("Invalid operand %d\n", op);
486 		user_ring_buffer__discard(ringbuf, msg);
487 		return -EINVAL;
488 	}
489 
490 	user_ring_buffer__submit(ringbuf, msg);
491 
492 	return 0;
493 }
494 
kick_kernel_read_messages(void)495 static void kick_kernel_read_messages(void)
496 {
497 	syscall(__NR_prctl);
498 }
499 
handle_kernel_msg(void * ctx,void * data,size_t len)500 static int handle_kernel_msg(void *ctx, void *data, size_t len)
501 {
502 	struct user_ringbuf_success *skel = ctx;
503 	struct test_msg *msg = data;
504 
505 	switch (msg->msg_op) {
506 	case TEST_MSG_OP_INC64:
507 		skel->bss->user_mutated += msg->operand_64;
508 		return 0;
509 	case TEST_MSG_OP_INC32:
510 		skel->bss->user_mutated += msg->operand_32;
511 		return 0;
512 	case TEST_MSG_OP_MUL64:
513 		skel->bss->user_mutated *= msg->operand_64;
514 		return 0;
515 	case TEST_MSG_OP_MUL32:
516 		skel->bss->user_mutated *= msg->operand_32;
517 		return 0;
518 	default:
519 		fprintf(stderr, "Invalid operand %d\n", msg->msg_op);
520 		return -EINVAL;
521 	}
522 }
523 
drain_kernel_messages_buffer(struct ring_buffer * kern_ringbuf,struct user_ringbuf_success * skel)524 static void drain_kernel_messages_buffer(struct ring_buffer *kern_ringbuf,
525 					 struct user_ringbuf_success *skel)
526 {
527 	int cnt;
528 
529 	cnt = ring_buffer__consume(kern_ringbuf);
530 	ASSERT_EQ(cnt, 8, "consume_kern_ringbuf");
531 	ASSERT_OK(skel->bss->err, "consume_kern_ringbuf_err");
532 }
533 
test_user_ringbuf_msg_protocol(void)534 static void test_user_ringbuf_msg_protocol(void)
535 {
536 	struct user_ringbuf_success *skel;
537 	struct user_ring_buffer *user_ringbuf;
538 	struct ring_buffer *kern_ringbuf;
539 	int err, i;
540 	__u64 expected_kern = 0;
541 
542 	err = load_skel_create_ringbufs(&skel, &kern_ringbuf, handle_kernel_msg, &user_ringbuf);
543 	if (!ASSERT_OK(err, "create_ringbufs"))
544 		return;
545 
546 	for (i = 0; i < 64; i++) {
547 		enum test_msg_op op = i % TEST_MSG_OP_NUM_OPS;
548 		__u64 operand_64 = TEST_OP_64;
549 		__u32 operand_32 = TEST_OP_32;
550 
551 		err = send_test_message(user_ringbuf, op, operand_64, operand_32);
552 		if (err) {
553 			/* Only assert on a failure to avoid spamming success logs. */
554 			ASSERT_OK(err, "send_test_message");
555 			goto cleanup;
556 		}
557 
558 		switch (op) {
559 		case TEST_MSG_OP_INC64:
560 			expected_kern += operand_64;
561 			break;
562 		case TEST_MSG_OP_INC32:
563 			expected_kern += operand_32;
564 			break;
565 		case TEST_MSG_OP_MUL64:
566 			expected_kern *= operand_64;
567 			break;
568 		case TEST_MSG_OP_MUL32:
569 			expected_kern *= operand_32;
570 			break;
571 		default:
572 			PRINT_FAIL("Unexpected op %d\n", op);
573 			goto cleanup;
574 		}
575 
576 		if (i % 8 == 0) {
577 			kick_kernel_read_messages();
578 			ASSERT_EQ(skel->bss->kern_mutated, expected_kern, "expected_kern");
579 			ASSERT_EQ(skel->bss->err, 0, "bpf_prog_err");
580 			drain_kernel_messages_buffer(kern_ringbuf, skel);
581 		}
582 	}
583 
584 cleanup:
585 	ring_buffer__free(kern_ringbuf);
586 	user_ring_buffer__free(user_ringbuf);
587 	user_ringbuf_success__destroy(skel);
588 }
589 
kick_kernel_cb(void * arg)590 static void *kick_kernel_cb(void *arg)
591 {
592 	/* Kick the kernel, causing it to drain the ring buffer and then wake
593 	 * up the test thread waiting on epoll.
594 	 */
595 	syscall(__NR_prlimit64);
596 
597 	return NULL;
598 }
599 
spawn_kick_thread_for_poll(void)600 static int spawn_kick_thread_for_poll(void)
601 {
602 	pthread_t thread;
603 
604 	return pthread_create(&thread, NULL, kick_kernel_cb, NULL);
605 }
606 
test_user_ringbuf_blocking_reserve(void)607 static void test_user_ringbuf_blocking_reserve(void)
608 {
609 	struct user_ringbuf_success *skel;
610 	struct user_ring_buffer *ringbuf;
611 	int err, num_written = 0;
612 	__u64 *token;
613 
614 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
615 	if (err)
616 		return;
617 
618 	ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
619 
620 	while (1) {
621 		/* Write samples until the buffer is full. */
622 		token = user_ring_buffer__reserve(ringbuf, sizeof(*token));
623 		if (!token)
624 			break;
625 
626 		*token = 0xdeadbeef;
627 
628 		user_ring_buffer__submit(ringbuf, token);
629 		num_written++;
630 	}
631 
632 	if (!ASSERT_GE(num_written, 0, "num_written"))
633 		goto cleanup;
634 
635 	/* Should not have read any samples until the kernel is kicked. */
636 	ASSERT_EQ(skel->bss->read, 0, "num_pre_kick");
637 
638 	/* We correctly time out after 1 second, without a sample. */
639 	token = user_ring_buffer__reserve_blocking(ringbuf, sizeof(*token), 1000);
640 	if (!ASSERT_EQ(token, NULL, "pre_kick_timeout_token"))
641 		goto cleanup;
642 
643 	err = spawn_kick_thread_for_poll();
644 	if (!ASSERT_EQ(err, 0, "deferred_kick_thread\n"))
645 		goto cleanup;
646 
647 	/* After spawning another thread that asynchronously kicks the kernel to
648 	 * drain the messages, we're able to block and successfully get a
649 	 * sample once we receive an event notification.
650 	 */
651 	token = user_ring_buffer__reserve_blocking(ringbuf, sizeof(*token), 10000);
652 
653 	if (!ASSERT_OK_PTR(token, "block_token"))
654 		goto cleanup;
655 
656 	ASSERT_GT(skel->bss->read, 0, "num_post_kill");
657 	ASSERT_LE(skel->bss->read, num_written, "num_post_kill");
658 	ASSERT_EQ(skel->bss->err, 0, "err_post_poll");
659 	user_ring_buffer__discard(ringbuf, token);
660 
661 cleanup:
662 	user_ring_buffer__free(ringbuf);
663 	user_ringbuf_success__destroy(skel);
664 }
665 
666 #define SUCCESS_TEST(_func) { _func, #_func }
667 
668 static struct {
669 	void (*test_callback)(void);
670 	const char *test_name;
671 } success_tests[] = {
672 	SUCCESS_TEST(test_user_ringbuf_mappings),
673 	SUCCESS_TEST(test_user_ringbuf_post_misaligned),
674 	SUCCESS_TEST(test_user_ringbuf_post_producer_wrong_offset),
675 	SUCCESS_TEST(test_user_ringbuf_post_larger_than_ringbuf_sz),
676 	SUCCESS_TEST(test_user_ringbuf_basic),
677 	SUCCESS_TEST(test_user_ringbuf_sample_full_ring_buffer),
678 	SUCCESS_TEST(test_user_ringbuf_post_alignment_autoadjust),
679 	SUCCESS_TEST(test_user_ringbuf_overfill),
680 	SUCCESS_TEST(test_user_ringbuf_discards_properly_ignored),
681 	SUCCESS_TEST(test_user_ringbuf_loop),
682 	SUCCESS_TEST(test_user_ringbuf_msg_protocol),
683 	SUCCESS_TEST(test_user_ringbuf_blocking_reserve),
684 };
685 
test_user_ringbuf(void)686 void test_user_ringbuf(void)
687 {
688 	int i;
689 
690 	c_ringbuf_size = getpagesize(); /* 1 page */
691 	c_max_entries = c_ringbuf_size / c_sample_size;
692 
693 	for (i = 0; i < ARRAY_SIZE(success_tests); i++) {
694 		if (!test__start_subtest(success_tests[i].test_name))
695 			continue;
696 
697 		success_tests[i].test_callback();
698 	}
699 
700 	RUN_TESTS(user_ringbuf_fail);
701 }
702