xref: /linux/tools/testing/selftests/bpf/prog_tests/usdt.c (revision 9a87ffc99ec8eb8d35eed7c4f816d75f5cc9662e)
1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3 #include <test_progs.h>
4 
5 #define _SDT_HAS_SEMAPHORES 1
6 #include "../sdt.h"
7 
8 #include "test_usdt.skel.h"
9 #include "test_urandom_usdt.skel.h"
10 
11 int lets_test_this(int);
12 
13 static volatile int idx = 2;
14 static volatile __u64 bla = 0xFEDCBA9876543210ULL;
15 static volatile short nums[] = {-1, -2, -3, -4};
16 
17 static volatile struct {
18 	int x;
19 	signed char y;
20 } t1 = { 1, -127 };
21 
22 #define SEC(name) __attribute__((section(name), used))
23 
24 unsigned short test_usdt0_semaphore SEC(".probes");
25 unsigned short test_usdt3_semaphore SEC(".probes");
26 unsigned short test_usdt12_semaphore SEC(".probes");
27 
trigger_func(int x)28 static void __always_inline trigger_func(int x) {
29 	long y = 42;
30 
31 	if (test_usdt0_semaphore)
32 		STAP_PROBE(test, usdt0);
33 	if (test_usdt3_semaphore)
34 		STAP_PROBE3(test, usdt3, x, y, &bla);
35 	if (test_usdt12_semaphore) {
36 		STAP_PROBE12(test, usdt12,
37 			     x, x + 1, y, x + y, 5,
38 			     y / 7, bla, &bla, -9, nums[x],
39 			     nums[idx], t1.y);
40 	}
41 }
42 
subtest_basic_usdt(void)43 static void subtest_basic_usdt(void)
44 {
45 	LIBBPF_OPTS(bpf_usdt_opts, opts);
46 	struct test_usdt *skel;
47 	struct test_usdt__bss *bss;
48 	int err;
49 
50 	skel = test_usdt__open_and_load();
51 	if (!ASSERT_OK_PTR(skel, "skel_open"))
52 		return;
53 
54 	bss = skel->bss;
55 	bss->my_pid = getpid();
56 
57 	err = test_usdt__attach(skel);
58 	if (!ASSERT_OK(err, "skel_attach"))
59 		goto cleanup;
60 
61 	/* usdt0 won't be auto-attached */
62 	opts.usdt_cookie = 0xcafedeadbeeffeed;
63 	skel->links.usdt0 = bpf_program__attach_usdt(skel->progs.usdt0,
64 						     0 /*self*/, "/proc/self/exe",
65 						     "test", "usdt0", &opts);
66 	if (!ASSERT_OK_PTR(skel->links.usdt0, "usdt0_link"))
67 		goto cleanup;
68 
69 	trigger_func(1);
70 
71 	ASSERT_EQ(bss->usdt0_called, 1, "usdt0_called");
72 	ASSERT_EQ(bss->usdt3_called, 1, "usdt3_called");
73 	ASSERT_EQ(bss->usdt12_called, 1, "usdt12_called");
74 
75 	ASSERT_EQ(bss->usdt0_cookie, 0xcafedeadbeeffeed, "usdt0_cookie");
76 	ASSERT_EQ(bss->usdt0_arg_cnt, 0, "usdt0_arg_cnt");
77 	ASSERT_EQ(bss->usdt0_arg_ret, -ENOENT, "usdt0_arg_ret");
78 
79 	/* auto-attached usdt3 gets default zero cookie value */
80 	ASSERT_EQ(bss->usdt3_cookie, 0, "usdt3_cookie");
81 	ASSERT_EQ(bss->usdt3_arg_cnt, 3, "usdt3_arg_cnt");
82 
83 	ASSERT_EQ(bss->usdt3_arg_rets[0], 0, "usdt3_arg1_ret");
84 	ASSERT_EQ(bss->usdt3_arg_rets[1], 0, "usdt3_arg2_ret");
85 	ASSERT_EQ(bss->usdt3_arg_rets[2], 0, "usdt3_arg3_ret");
86 	ASSERT_EQ(bss->usdt3_args[0], 1, "usdt3_arg1");
87 	ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2");
88 	ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3");
89 
90 	/* auto-attached usdt12 gets default zero cookie value */
91 	ASSERT_EQ(bss->usdt12_cookie, 0, "usdt12_cookie");
92 	ASSERT_EQ(bss->usdt12_arg_cnt, 12, "usdt12_arg_cnt");
93 
94 	ASSERT_EQ(bss->usdt12_args[0], 1, "usdt12_arg1");
95 	ASSERT_EQ(bss->usdt12_args[1], 1 + 1, "usdt12_arg2");
96 	ASSERT_EQ(bss->usdt12_args[2], 42, "usdt12_arg3");
97 	ASSERT_EQ(bss->usdt12_args[3], 42 + 1, "usdt12_arg4");
98 	ASSERT_EQ(bss->usdt12_args[4], 5, "usdt12_arg5");
99 	ASSERT_EQ(bss->usdt12_args[5], 42 / 7, "usdt12_arg6");
100 	ASSERT_EQ(bss->usdt12_args[6], bla, "usdt12_arg7");
101 	ASSERT_EQ(bss->usdt12_args[7], (uintptr_t)&bla, "usdt12_arg8");
102 	ASSERT_EQ(bss->usdt12_args[8], -9, "usdt12_arg9");
103 	ASSERT_EQ(bss->usdt12_args[9], nums[1], "usdt12_arg10");
104 	ASSERT_EQ(bss->usdt12_args[10], nums[idx], "usdt12_arg11");
105 	ASSERT_EQ(bss->usdt12_args[11], t1.y, "usdt12_arg12");
106 
107 	/* trigger_func() is marked __always_inline, so USDT invocations will be
108 	 * inlined in two different places, meaning that each USDT will have
109 	 * at least 2 different places to be attached to. This verifies that
110 	 * bpf_program__attach_usdt() handles this properly and attaches to
111 	 * all possible places of USDT invocation.
112 	 */
113 	trigger_func(2);
114 
115 	ASSERT_EQ(bss->usdt0_called, 2, "usdt0_called");
116 	ASSERT_EQ(bss->usdt3_called, 2, "usdt3_called");
117 	ASSERT_EQ(bss->usdt12_called, 2, "usdt12_called");
118 
119 	/* only check values that depend on trigger_func()'s input value */
120 	ASSERT_EQ(bss->usdt3_args[0], 2, "usdt3_arg1");
121 
122 	ASSERT_EQ(bss->usdt12_args[0], 2, "usdt12_arg1");
123 	ASSERT_EQ(bss->usdt12_args[1], 2 + 1, "usdt12_arg2");
124 	ASSERT_EQ(bss->usdt12_args[3], 42 + 2, "usdt12_arg4");
125 	ASSERT_EQ(bss->usdt12_args[9], nums[2], "usdt12_arg10");
126 
127 	/* detach and re-attach usdt3 */
128 	bpf_link__destroy(skel->links.usdt3);
129 
130 	opts.usdt_cookie = 0xBADC00C51E;
131 	skel->links.usdt3 = bpf_program__attach_usdt(skel->progs.usdt3, -1 /* any pid */,
132 						     "/proc/self/exe", "test", "usdt3", &opts);
133 	if (!ASSERT_OK_PTR(skel->links.usdt3, "usdt3_reattach"))
134 		goto cleanup;
135 
136 	trigger_func(3);
137 
138 	ASSERT_EQ(bss->usdt3_called, 3, "usdt3_called");
139 	/* this time usdt3 has custom cookie */
140 	ASSERT_EQ(bss->usdt3_cookie, 0xBADC00C51E, "usdt3_cookie");
141 	ASSERT_EQ(bss->usdt3_arg_cnt, 3, "usdt3_arg_cnt");
142 
143 	ASSERT_EQ(bss->usdt3_arg_rets[0], 0, "usdt3_arg1_ret");
144 	ASSERT_EQ(bss->usdt3_arg_rets[1], 0, "usdt3_arg2_ret");
145 	ASSERT_EQ(bss->usdt3_arg_rets[2], 0, "usdt3_arg3_ret");
146 	ASSERT_EQ(bss->usdt3_args[0], 3, "usdt3_arg1");
147 	ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2");
148 	ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3");
149 
150 cleanup:
151 	test_usdt__destroy(skel);
152 }
153 
154 unsigned short test_usdt_100_semaphore SEC(".probes");
155 unsigned short test_usdt_300_semaphore SEC(".probes");
156 unsigned short test_usdt_400_semaphore SEC(".probes");
157 
158 #define R10(F, X)  F(X+0); F(X+1);F(X+2); F(X+3); F(X+4); \
159 		   F(X+5); F(X+6); F(X+7); F(X+8); F(X+9);
160 #define R100(F, X) R10(F,X+ 0);R10(F,X+10);R10(F,X+20);R10(F,X+30);R10(F,X+40); \
161 		   R10(F,X+50);R10(F,X+60);R10(F,X+70);R10(F,X+80);R10(F,X+90);
162 
163 /* carefully control that we get exactly 100 inlines by preventing inlining */
f100(int x)164 static void __always_inline f100(int x)
165 {
166 	STAP_PROBE1(test, usdt_100, x);
167 }
168 
trigger_100_usdts(void)169 __weak void trigger_100_usdts(void)
170 {
171 	R100(f100, 0);
172 }
173 
174 /* we shouldn't be able to attach to test:usdt2_300 USDT as we don't have as
175  * many slots for specs. It's important that each STAP_PROBE2() invocation
176  * (after untolling) gets different arg spec due to compiler inlining i as
177  * a constant
178  */
f300(int x)179 static void __always_inline f300(int x)
180 {
181 	STAP_PROBE1(test, usdt_300, x);
182 }
183 
trigger_300_usdts(void)184 __weak void trigger_300_usdts(void)
185 {
186 	R100(f300, 0);
187 	R100(f300, 100);
188 	R100(f300, 200);
189 }
190 
f400(int x)191 static void __always_inline f400(int x __attribute__((unused)))
192 {
193 	STAP_PROBE1(test, usdt_400, 400);
194 }
195 
196 /* this time we have 400 different USDT call sites, but they have uniform
197  * argument location, so libbpf's spec string deduplication logic should keep
198  * spec count use very small and so we should be able to attach to all 400
199  * call sites
200  */
trigger_400_usdts(void)201 __weak void trigger_400_usdts(void)
202 {
203 	R100(f400, 0);
204 	R100(f400, 100);
205 	R100(f400, 200);
206 	R100(f400, 300);
207 }
208 
subtest_multispec_usdt(void)209 static void subtest_multispec_usdt(void)
210 {
211 	LIBBPF_OPTS(bpf_usdt_opts, opts);
212 	struct test_usdt *skel;
213 	struct test_usdt__bss *bss;
214 	int err, i;
215 
216 	skel = test_usdt__open_and_load();
217 	if (!ASSERT_OK_PTR(skel, "skel_open"))
218 		return;
219 
220 	bss = skel->bss;
221 	bss->my_pid = getpid();
222 
223 	err = test_usdt__attach(skel);
224 	if (!ASSERT_OK(err, "skel_attach"))
225 		goto cleanup;
226 
227 	/* usdt_100 is auto-attached and there are 100 inlined call sites,
228 	 * let's validate that all of them are properly attached to and
229 	 * handled from BPF side
230 	 */
231 	trigger_100_usdts();
232 
233 	ASSERT_EQ(bss->usdt_100_called, 100, "usdt_100_called");
234 	ASSERT_EQ(bss->usdt_100_sum, 99 * 100 / 2, "usdt_100_sum");
235 
236 	/* Stress test free spec ID tracking. By default libbpf allows up to
237 	 * 256 specs to be used, so if we don't return free spec IDs back
238 	 * after few detachments and re-attachments we should run out of
239 	 * available spec IDs.
240 	 */
241 	for (i = 0; i < 2; i++) {
242 		bpf_link__destroy(skel->links.usdt_100);
243 
244 		skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1,
245 							        "/proc/self/exe",
246 								"test", "usdt_100", NULL);
247 		if (!ASSERT_OK_PTR(skel->links.usdt_100, "usdt_100_reattach"))
248 			goto cleanup;
249 
250 		bss->usdt_100_sum = 0;
251 		trigger_100_usdts();
252 
253 		ASSERT_EQ(bss->usdt_100_called, (i + 1) * 100 + 100, "usdt_100_called");
254 		ASSERT_EQ(bss->usdt_100_sum, 99 * 100 / 2, "usdt_100_sum");
255 	}
256 
257 	/* Now let's step it up and try to attach USDT that requires more than
258 	 * 256 attach points with different specs for each.
259 	 * Note that we need trigger_300_usdts() only to actually have 300
260 	 * USDT call sites, we are not going to actually trace them.
261 	 */
262 	trigger_300_usdts();
263 
264 	/* we'll reuse usdt_100 BPF program for usdt_300 test */
265 	bpf_link__destroy(skel->links.usdt_100);
266 	skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1, "/proc/self/exe",
267 							"test", "usdt_300", NULL);
268 	err = -errno;
269 	if (!ASSERT_ERR_PTR(skel->links.usdt_100, "usdt_300_bad_attach"))
270 		goto cleanup;
271 	ASSERT_EQ(err, -E2BIG, "usdt_300_attach_err");
272 
273 	/* let's check that there are no "dangling" BPF programs attached due
274 	 * to partial success of the above test:usdt_300 attachment
275 	 */
276 	bss->usdt_100_called = 0;
277 	bss->usdt_100_sum = 0;
278 
279 	f300(777); /* this is 301st instance of usdt_300 */
280 
281 	ASSERT_EQ(bss->usdt_100_called, 0, "usdt_301_called");
282 	ASSERT_EQ(bss->usdt_100_sum, 0, "usdt_301_sum");
283 
284 	/* This time we have USDT with 400 inlined invocations, but arg specs
285 	 * should be the same across all sites, so libbpf will only need to
286 	 * use one spec and thus we'll be able to attach 400 uprobes
287 	 * successfully.
288 	 *
289 	 * Again, we are reusing usdt_100 BPF program.
290 	 */
291 	skel->links.usdt_100 = bpf_program__attach_usdt(skel->progs.usdt_100, -1,
292 							"/proc/self/exe",
293 							"test", "usdt_400", NULL);
294 	if (!ASSERT_OK_PTR(skel->links.usdt_100, "usdt_400_attach"))
295 		goto cleanup;
296 
297 	trigger_400_usdts();
298 
299 	ASSERT_EQ(bss->usdt_100_called, 400, "usdt_400_called");
300 	ASSERT_EQ(bss->usdt_100_sum, 400 * 400, "usdt_400_sum");
301 
302 cleanup:
303 	test_usdt__destroy(skel);
304 }
305 
urand_spawn(int * pid)306 static FILE *urand_spawn(int *pid)
307 {
308 	FILE *f;
309 
310 	/* urandom_read's stdout is wired into f */
311 	f = popen("./urandom_read 1 report-pid", "r");
312 	if (!f)
313 		return NULL;
314 
315 	if (fscanf(f, "%d", pid) != 1) {
316 		pclose(f);
317 		errno = EINVAL;
318 		return NULL;
319 	}
320 
321 	return f;
322 }
323 
urand_trigger(FILE ** urand_pipe)324 static int urand_trigger(FILE **urand_pipe)
325 {
326 	int exit_code;
327 
328 	/* pclose() waits for child process to exit and returns their exit code */
329 	exit_code = pclose(*urand_pipe);
330 	*urand_pipe = NULL;
331 
332 	return exit_code;
333 }
334 
subtest_urandom_usdt(bool auto_attach)335 static void subtest_urandom_usdt(bool auto_attach)
336 {
337 	struct test_urandom_usdt *skel;
338 	struct test_urandom_usdt__bss *bss;
339 	struct bpf_link *l;
340 	FILE *urand_pipe = NULL;
341 	int err, urand_pid = 0;
342 
343 	skel = test_urandom_usdt__open_and_load();
344 	if (!ASSERT_OK_PTR(skel, "skel_open"))
345 		return;
346 
347 	urand_pipe = urand_spawn(&urand_pid);
348 	if (!ASSERT_OK_PTR(urand_pipe, "urand_spawn"))
349 		goto cleanup;
350 
351 	bss = skel->bss;
352 	bss->urand_pid = urand_pid;
353 
354 	if (auto_attach) {
355 		err = test_urandom_usdt__attach(skel);
356 		if (!ASSERT_OK(err, "skel_auto_attach"))
357 			goto cleanup;
358 	} else {
359 		l = bpf_program__attach_usdt(skel->progs.urand_read_without_sema,
360 					     urand_pid, "./urandom_read",
361 					     "urand", "read_without_sema", NULL);
362 		if (!ASSERT_OK_PTR(l, "urand_without_sema_attach"))
363 			goto cleanup;
364 		skel->links.urand_read_without_sema = l;
365 
366 		l = bpf_program__attach_usdt(skel->progs.urand_read_with_sema,
367 					     urand_pid, "./urandom_read",
368 					     "urand", "read_with_sema", NULL);
369 		if (!ASSERT_OK_PTR(l, "urand_with_sema_attach"))
370 			goto cleanup;
371 		skel->links.urand_read_with_sema = l;
372 
373 		l = bpf_program__attach_usdt(skel->progs.urandlib_read_without_sema,
374 					     urand_pid, "./liburandom_read.so",
375 					     "urandlib", "read_without_sema", NULL);
376 		if (!ASSERT_OK_PTR(l, "urandlib_without_sema_attach"))
377 			goto cleanup;
378 		skel->links.urandlib_read_without_sema = l;
379 
380 		l = bpf_program__attach_usdt(skel->progs.urandlib_read_with_sema,
381 					     urand_pid, "./liburandom_read.so",
382 					     "urandlib", "read_with_sema", NULL);
383 		if (!ASSERT_OK_PTR(l, "urandlib_with_sema_attach"))
384 			goto cleanup;
385 		skel->links.urandlib_read_with_sema = l;
386 
387 	}
388 
389 	/* trigger urandom_read USDTs */
390 	ASSERT_OK(urand_trigger(&urand_pipe), "urand_exit_code");
391 
392 	ASSERT_EQ(bss->urand_read_without_sema_call_cnt, 1, "urand_wo_sema_cnt");
393 	ASSERT_EQ(bss->urand_read_without_sema_buf_sz_sum, 256, "urand_wo_sema_sum");
394 
395 	ASSERT_EQ(bss->urand_read_with_sema_call_cnt, 1, "urand_w_sema_cnt");
396 	ASSERT_EQ(bss->urand_read_with_sema_buf_sz_sum, 256, "urand_w_sema_sum");
397 
398 	ASSERT_EQ(bss->urandlib_read_without_sema_call_cnt, 1, "urandlib_wo_sema_cnt");
399 	ASSERT_EQ(bss->urandlib_read_without_sema_buf_sz_sum, 256, "urandlib_wo_sema_sum");
400 
401 	ASSERT_EQ(bss->urandlib_read_with_sema_call_cnt, 1, "urandlib_w_sema_cnt");
402 	ASSERT_EQ(bss->urandlib_read_with_sema_buf_sz_sum, 256, "urandlib_w_sema_sum");
403 
404 cleanup:
405 	if (urand_pipe)
406 		pclose(urand_pipe);
407 	test_urandom_usdt__destroy(skel);
408 }
409 
test_usdt(void)410 void test_usdt(void)
411 {
412 	if (test__start_subtest("basic"))
413 		subtest_basic_usdt();
414 	if (test__start_subtest("multispec"))
415 		subtest_multispec_usdt();
416 	if (test__start_subtest("urand_auto_attach"))
417 		subtest_urandom_usdt(true /* auto_attach */);
418 	if (test__start_subtest("urand_pid_attach"))
419 		subtest_urandom_usdt(false /* auto_attach */);
420 }
421