1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * in kernel monitor support: allows rv to control in-kernel monitors.
4  *
5  * Copyright (C) 2022 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
6  */
7 #include <getopt.h>
8 #include <stdlib.h>
9 #include <string.h>
10 #include <errno.h>
11 #include <unistd.h>
12 
13 #include <trace.h>
14 #include <utils.h>
15 #include <rv.h>
16 
17 static int config_has_id;
18 static int config_my_pid;
19 static int config_trace;
20 
21 static char *config_initial_reactor;
22 static char *config_reactor;
23 
24 /*
25  * __ikm_read_enable - reads monitor's enable status
26  *
27  * __does not log errors.
28  *
29  * Returns the current status, or -1 if the monitor does not exist,
30  * __hence not logging errors.
31  */
32 static int __ikm_read_enable(char *monitor_name)
33 {
34 	char path[MAX_PATH];
35 	long long enabled;
36 	int retval;
37 
38 	snprintf(path, MAX_PATH, "rv/monitors/%s/enable", monitor_name);
39 
40 	retval = tracefs_instance_file_read_number(NULL, path, &enabled);
41 	if (retval < 0)
42 		return -1;
43 
44 	return enabled;
45 }
46 
47 /*
48  * ikm_read_enable - reads monitor's enable status
49  *
50  * Returns the current status, or -1 on error.
51  */
52 static int ikm_read_enable(char *monitor_name)
53 {
54 	int enabled;
55 
56 	enabled = __ikm_read_enable(monitor_name);
57 	if (enabled < 0) {
58 		err_msg("ikm: fail read enabled: %d\n", enabled);
59 		return -1;
60 	}
61 
62 	debug_msg("ikm: read enabled: %d\n", enabled);
63 
64 	return enabled;
65 }
66 
67 /*
68  * ikm_write_enable - write to the monitor's enable file
69  *
70  * Return the number of bytes written, -1 on error.
71  */
72 static int ikm_write_enable(char *monitor_name, char *enable_disable)
73 {
74 	char path[MAX_PATH];
75 	int retval;
76 
77 	debug_msg("ikm: writing enabled: %s\n", enable_disable);
78 
79 	snprintf(path, MAX_PATH, "rv/monitors/%s/enable", monitor_name);
80 	retval = tracefs_instance_file_write(NULL, path, enable_disable);
81 	if (retval < strlen(enable_disable)) {
82 		err_msg("ikm: writing enabled: %s\n", enable_disable);
83 		return -1;
84 	}
85 
86 	return retval;
87 }
88 
89 /*
90  * ikm_enable - enable a monitor
91  *
92  * Returns -1 on failure. Success otherwise.
93  */
94 static int ikm_enable(char *monitor_name)
95 {
96 	return ikm_write_enable(monitor_name, "1");
97 }
98 
99 /*
100  * ikm_disable - disable a monitor
101  *
102  * Returns -1 on failure. Success otherwise.
103  */
104 static int ikm_disable(char *monitor_name)
105 {
106 	return ikm_write_enable(monitor_name, "0");
107 }
108 
109 /*
110  * ikm_read_desc - read monitors' description
111  *
112  * Return a dynamically allocated string with the monitor's
113  * description, NULL otherwise.
114  */
115 static char *ikm_read_desc(char *monitor_name)
116 {
117 	char path[MAX_PATH];
118 	char *desc;
119 
120 	snprintf(path, MAX_PATH, "rv/monitors/%s/desc", monitor_name);
121 	desc = tracefs_instance_file_read(NULL, path, NULL);
122 	if (!desc) {
123 		err_msg("ikm: error reading monitor %s desc\n", monitor_name);
124 		return NULL;
125 	}
126 
127 	*strstr(desc, "\n") = '\0';
128 
129 	return desc;
130 }
131 
132 /*
133  * ikm_fill_monitor_definition - fill monitor's definition
134  *
135  * Returns -1 on error, 0 otherwise.
136  */
137 static int ikm_fill_monitor_definition(char *name, struct monitor *ikm)
138 {
139 	int enabled;
140 	char *desc;
141 
142 	enabled = ikm_read_enable(name);
143 	if (enabled < 0) {
144 		err_msg("ikm: monitor %s fail to read enable file, bug?\n", name);
145 		return -1;
146 	}
147 
148 	desc = ikm_read_desc(name);
149 	if (!desc) {
150 		err_msg("ikm: monitor %s does not have desc file, bug?\n", name);
151 		return -1;
152 	}
153 
154 	strncpy(ikm->name, name, MAX_DA_NAME_LEN);
155 	ikm->enabled = enabled;
156 	strncpy(ikm->desc, desc, MAX_DESCRIPTION);
157 
158 	free(desc);
159 
160 	return 0;
161 }
162 
163 /*
164  * ikm_write_reactor - switch the reactor to *reactor
165  *
166  * Return the number or characters written, -1 on error.
167  */
168 static int ikm_write_reactor(char *monitor_name, char *reactor)
169 {
170 	char path[MAX_PATH];
171 	int retval;
172 
173 	snprintf(path, MAX_PATH, "rv/monitors/%s/reactors", monitor_name);
174 	retval = tracefs_instance_file_write(NULL, path, reactor);
175 	debug_msg("ikm: write \"%s\" reactors: %d\n", reactor, retval);
176 
177 	return retval;
178 }
179 
180 /*
181  * ikm_read_reactor - read the reactors file
182  *
183  * Returns a dynamically allocated string with monitor's
184  * available reactors, or NULL on error.
185  */
186 static char *ikm_read_reactor(char *monitor_name)
187 {
188 	char path[MAX_PATH];
189 	char *reactors;
190 
191 	snprintf(path, MAX_PATH, "rv/monitors/%s/reactors", monitor_name);
192 	reactors = tracefs_instance_file_read(NULL, path, NULL);
193 	if (!reactors) {
194 		err_msg("ikm: fail reading monitor's %s reactors file\n", monitor_name);
195 		return NULL;
196 	}
197 
198 	return reactors;
199 }
200 
201 /*
202  * ikm_get_current_reactor - get the current enabled reactor
203  *
204  * Reads the reactors file and find the currently enabled
205  * [reactor].
206  *
207  * Returns a dynamically allocated memory with the current
208  * reactor. NULL otherwise.
209  */
210 static char *ikm_get_current_reactor(char *monitor_name)
211 {
212 	char *reactors = ikm_read_reactor(monitor_name);
213 	char *start;
214 	char *end;
215 	char *curr_reactor;
216 
217 	if (!reactors)
218 		return NULL;
219 
220 	start = strstr(reactors, "[");
221 	if (!start)
222 		goto out_free;
223 
224 	start++;
225 
226 	end = strstr(start, "]");
227 	if (!end)
228 		goto out_free;
229 
230 	*end = '\0';
231 
232 	curr_reactor = calloc(strlen(start) + 1, sizeof(char));
233 	if (!curr_reactor)
234 		goto out_free;
235 
236 	strncpy(curr_reactor, start, strlen(start));
237 	debug_msg("ikm: read current reactor %s\n", curr_reactor);
238 
239 out_free:
240 	free(reactors);
241 
242 	return curr_reactor;
243 }
244 
245 static int ikm_has_id(char *monitor_name)
246 {
247 	char path[MAX_PATH];
248 	char *format;
249 	int has_id;
250 
251 	snprintf(path, MAX_PATH, "events/rv/event_%s/format", monitor_name);
252 	format = tracefs_instance_file_read(NULL, path, NULL);
253 	if (!format) {
254 		err_msg("ikm: fail reading monitor's %s format event file\n", monitor_name);
255 		return -1;
256 	}
257 
258 	/* print fmt: "%d: %s x %s -> %s %s", REC->id, ... */
259 	has_id = !!strstr(format, "REC->id");
260 
261 	debug_msg("ikm: monitor %s has id: %s\n", monitor_name, has_id ? "yes" : "no");
262 
263 	free(format);
264 
265 	return has_id;
266 }
267 
268 /**
269  * ikm_list_monitors - list all available monitors
270  *
271  * Returns 0 on success, -1 otherwise.
272  */
273 int ikm_list_monitors(void)
274 {
275 	char *available_monitors;
276 	struct monitor ikm;
277 	char *curr, *next;
278 	int retval;
279 
280 	available_monitors = tracefs_instance_file_read(NULL, "rv/available_monitors", NULL);
281 
282 	if (!available_monitors) {
283 		err_msg("ikm: available monitors is not available, is CONFIG_RV enabled?\n");
284 		return -1;
285 	}
286 
287 	curr = available_monitors;
288 	do {
289 		next = strstr(curr, "\n");
290 		*next = '\0';
291 
292 		retval = ikm_fill_monitor_definition(curr, &ikm);
293 		if (retval)
294 			err_msg("ikm: error reading %d in kernel monitor, skipping\n", curr);
295 
296 		printf("%-24s %s %s\n", ikm.name, ikm.desc, ikm.enabled ? "[ON]" : "[OFF]");
297 		curr = ++next;
298 
299 	} while (strlen(curr));
300 
301 	free(available_monitors);
302 
303 	return 0;
304 }
305 
306 static void ikm_print_header(struct trace_seq *s)
307 {
308 	trace_seq_printf(s, "%16s-%-8s %5s %5s ", "<TASK>", "PID", "[CPU]", "TYPE");
309 	if (config_has_id)
310 		trace_seq_printf(s, "%8s ", "ID");
311 
312 	trace_seq_printf(s, "%24s x %-24s -> %-24s %s\n",
313 			 "STATE",
314 			 "EVENT",
315 			 "NEXT_STATE",
316 			 "FINAL");
317 
318 	trace_seq_printf(s, "%16s %-8s %5s %5s ", " | ", " | ", " | ", " | ");
319 
320 	if (config_has_id)
321 		trace_seq_printf(s, "%8s ", " | ");
322 
323 	trace_seq_printf(s, "%24s   %-24s    %-24s %s\n",
324 			 " | ",
325 			 " | ",
326 			 " | ",
327 			 "|");
328 
329 }
330 
331 /*
332  * ikm_event_handler - callback to handle event events
333  *
334  * Called any time a rv:"monitor"_event events is generated.
335  * It parses and print event.
336  */
337 static int
338 ikm_event_handler(struct trace_seq *s, struct tep_record *record,
339 		  struct tep_event *trace_event, void *context)
340 {
341 	/* if needed: struct trace_instance *inst = context; */
342 	char *state, *event, *next_state;
343 	unsigned long long final_state;
344 	unsigned long long pid;
345 	unsigned long long id;
346 	int cpu = record->cpu;
347 	int val;
348 
349 	if (config_has_id)
350 		tep_get_field_val(s, trace_event, "id", record, &id, 1);
351 
352 	tep_get_common_field_val(s, trace_event, "common_pid", record, &pid, 1);
353 
354 	if (config_has_id && (config_my_pid == id))
355 		return 0;
356 	else if (config_my_pid && (config_my_pid == pid))
357 		return 0;
358 
359 	tep_print_event(trace_event->tep, s, record, "%16s-%-8d ", TEP_PRINT_COMM, TEP_PRINT_PID);
360 
361 	trace_seq_printf(s, "[%.3d] event ", cpu);
362 
363 	if (config_has_id)
364 		trace_seq_printf(s, "%8llu ", id);
365 
366 	state = tep_get_field_raw(s, trace_event, "state", record, &val, 0);
367 	event = tep_get_field_raw(s, trace_event, "event", record, &val, 0);
368 	next_state = tep_get_field_raw(s, trace_event, "next_state", record, &val, 0);
369 	tep_get_field_val(s, trace_event, "final_state", record, &final_state, 1);
370 
371 	trace_seq_printf(s, "%24s x %-24s -> %-24s %s\n",
372 			 state,
373 			 event,
374 			 next_state,
375 			 final_state ? "Y" : "N");
376 
377 	trace_seq_do_printf(s);
378 	trace_seq_reset(s);
379 
380 	return 0;
381 }
382 
383 /*
384  * ikm_error_handler - callback to handle error events
385  *
386  * Called any time a rv:"monitor"_errors events is generated.
387  * It parses and print event.
388  */
389 static int
390 ikm_error_handler(struct trace_seq *s, struct tep_record *record,
391 		  struct tep_event *trace_event, void *context)
392 {
393 	unsigned long long pid, id;
394 	int cpu = record->cpu;
395 	char *state, *event;
396 	int val;
397 
398 	if (config_has_id)
399 		tep_get_field_val(s, trace_event, "id", record, &id, 1);
400 
401 	tep_get_common_field_val(s, trace_event, "common_pid", record, &pid, 1);
402 
403 	if (config_has_id && config_my_pid == id)
404 		return 0;
405 	else if (config_my_pid == pid)
406 		return 0;
407 
408 	trace_seq_printf(s, "%8lld [%03d] error ", pid, cpu);
409 
410 	if (config_has_id)
411 		trace_seq_printf(s, "%8llu ", id);
412 
413 	state = tep_get_field_raw(s, trace_event, "state", record, &val, 0);
414 	event = tep_get_field_raw(s, trace_event, "event", record, &val, 0);
415 
416 	trace_seq_printf(s, "%24s x %s\n", state, event);
417 
418 	trace_seq_do_printf(s);
419 	trace_seq_reset(s);
420 
421 	return 0;
422 }
423 
424 /*
425  * ikm_setup_trace_instance - set up a tracing instance to collect data
426  *
427  * Create a trace instance, enable rv: events and enable the trace.
428  *
429  * Returns the trace_instance * with all set, NULL otherwise.
430  */
431 static struct trace_instance *ikm_setup_trace_instance(char *monitor_name)
432 {
433 	char event[MAX_DA_NAME_LEN + 7]; /* max(error_,event_) + '0' = 7 */
434 	struct trace_instance *inst;
435 	int retval;
436 
437 	if (!config_trace)
438 		return NULL;
439 
440 	config_has_id = ikm_has_id(monitor_name);
441 	if (config_has_id < 0) {
442 		err_msg("ikm: failed to read monitor %s event format\n", monitor_name);
443 		goto out_err;
444 	}
445 
446 	/* alloc data */
447 	inst = calloc(1, sizeof(*inst));
448 	if (!inst) {
449 		err_msg("ikm: failed to allocate trace instance");
450 		goto out_err;
451 	}
452 
453 	retval = trace_instance_init(inst, monitor_name);
454 	if (retval)
455 		goto out_free;
456 
457 	/* enable events */
458 	snprintf(event, sizeof(event), "event_%s", monitor_name);
459 	retval = tracefs_event_enable(inst->inst, "rv",  event);
460 	if (retval)
461 		goto out_inst;
462 
463 	tep_register_event_handler(inst->tep, -1, "rv", event,
464 				   ikm_event_handler, NULL);
465 
466 	snprintf(event, sizeof(event), "error_%s", monitor_name);
467 	retval = tracefs_event_enable(inst->inst, "rv", event);
468 	if (retval)
469 		goto out_inst;
470 
471 	tep_register_event_handler(inst->tep, -1, "rv", event,
472 				   ikm_error_handler, NULL);
473 
474 	/* ready to enable */
475 	tracefs_trace_on(inst->inst);
476 
477 	return inst;
478 
479 out_inst:
480 	trace_instance_destroy(inst);
481 out_free:
482 	free(inst);
483 out_err:
484 	return NULL;
485 }
486 
487 /**
488  * ikm_destroy_trace_instance - destroy a previously created instance
489  */
490 static void ikm_destroy_trace_instance(struct trace_instance *inst)
491 {
492 	if (!inst)
493 		return;
494 
495 	trace_instance_destroy(inst);
496 	free(inst);
497 }
498 
499 /*
500  * ikm_usage_print_reactors - print all available reactors, one per line.
501  */
502 static void ikm_usage_print_reactors(void)
503 {
504 	char *reactors = tracefs_instance_file_read(NULL, "rv/available_reactors", NULL);
505 	char *start, *end;
506 
507 	if (!reactors)
508 		return;
509 
510 	fprintf(stderr, "  available reactors:");
511 
512 	start = reactors;
513 	end = strstr(start, "\n");
514 
515 	while (end) {
516 		*end = '\0';
517 
518 		fprintf(stderr, " %s", start);
519 
520 		start = ++end;
521 		end = strstr(start, "\n");
522 	};
523 
524 	fprintf(stderr, "\n");
525 }
526 /*
527  * ikm_usage - print usage
528  */
529 static void ikm_usage(int exit_val, char *monitor_name, const char *fmt, ...)
530 {
531 
532 	char message[1024];
533 	va_list ap;
534 	int i;
535 
536 	static const char *const usage[] = {
537 		"",
538 		"	-h/--help: print this menu and the reactor list",
539 		"	-r/--reactor 'reactor': enables the 'reactor'",
540 		"	-s/--self: when tracing (-t), also trace rv command",
541 		"	-t/--trace: trace monitor's event",
542 		"	-v/--verbose: print debug messages",
543 		"",
544 		NULL,
545 	};
546 
547 	va_start(ap, fmt);
548 	vsnprintf(message, sizeof(message), fmt, ap);
549 	va_end(ap);
550 
551 	fprintf(stderr, "  %s\n", message);
552 
553 	fprintf(stderr, "\n  usage: rv mon %s [-h] [-q] [-r reactor] [-s] [-v]", monitor_name);
554 
555 	for (i = 0; usage[i]; i++)
556 		fprintf(stderr, "%s\n", usage[i]);
557 
558 	ikm_usage_print_reactors();
559 	exit(exit_val);
560 }
561 
562 /*
563  * parse_arguments - parse arguments and set config
564  */
565 static int parse_arguments(char *monitor_name, int argc, char **argv)
566 {
567 	int c, retval;
568 
569 	config_my_pid = getpid();
570 
571 	while (1) {
572 		static struct option long_options[] = {
573 			{"help",		no_argument,		0, 'h'},
574 			{"reactor",		required_argument,	0, 'r'},
575 			{"self",		no_argument,		0, 's'},
576 			{"trace",		no_argument,		0, 't'},
577 			{"verbose",		no_argument,		0, 'v'},
578 			{0, 0, 0, 0}
579 		};
580 
581 		/* getopt_long stores the option index here. */
582 		int option_index = 0;
583 
584 		c = getopt_long(argc, argv, "hr:stv", long_options, &option_index);
585 
586 		/* detect the end of the options. */
587 		if (c == -1)
588 			break;
589 
590 		switch (c) {
591 		case 'h':
592 			ikm_usage(0, monitor_name, "help:");
593 			break;
594 		case 'r':
595 			config_reactor = optarg;
596 			break;
597 		case 's':
598 			config_my_pid = 0;
599 			break;
600 		case 't':
601 			config_trace = 1;
602 			break;
603 		case 'v':
604 			config_debug = 1;
605 			break;
606 		}
607 	}
608 
609 	if (config_reactor) {
610 		config_initial_reactor = ikm_get_current_reactor(monitor_name);
611 		if (!config_initial_reactor)
612 			ikm_usage(1, monitor_name,
613 				  "ikm: failed to read current reactor, are reactors enabled?");
614 
615 		retval = ikm_write_reactor(monitor_name, config_reactor);
616 		if (retval <= 0)
617 			ikm_usage(1, monitor_name,
618 				  "ikm: failed to set %s reactor, is it available?",
619 				  config_reactor);
620 	}
621 
622 	debug_msg("ikm: my pid is %d\n", config_my_pid);
623 
624 	return 0;
625 }
626 
627 /**
628  * ikm_run_monitor - apply configs and run the monitor
629  *
630  * Returns 1 if a monitor was found an executed, 0 if no
631  * monitors were found, or -1 on error.
632  */
633 int ikm_run_monitor(char *monitor_name, int argc, char **argv)
634 {
635 	struct trace_instance *inst = NULL;
636 	int retval;
637 
638 	/*
639 	 * Check if monitor exists by seeing it is enabled.
640 	 */
641 	retval = __ikm_read_enable(monitor_name);
642 	if (retval < 0)
643 		return 0;
644 
645 	if (retval) {
646 		err_msg("ikm: monitor %s (in-kernel) is already enabled\n", monitor_name);
647 		return -1;
648 	}
649 
650 	/* we should be good to go */
651 	retval = parse_arguments(monitor_name, argc, argv);
652 	if (retval)
653 		ikm_usage(1, monitor_name, "ikm: failed parsing arguments");
654 
655 	if (config_trace) {
656 		inst = ikm_setup_trace_instance(monitor_name);
657 		if (!inst)
658 			return -1;
659 	}
660 
661 	retval = ikm_enable(monitor_name);
662 	if (retval < 0)
663 		goto out_free_instance;
664 
665 	if (config_trace)
666 		ikm_print_header(inst->seq);
667 
668 	while (!should_stop()) {
669 		if (config_trace) {
670 			retval = tracefs_iterate_raw_events(inst->tep,
671 							    inst->inst,
672 							    NULL,
673 							    0,
674 							    collect_registered_events,
675 							    inst);
676 			if (retval) {
677 				err_msg("ikm: error reading trace buffer\n");
678 				break;
679 			}
680 		}
681 
682 		sleep(1);
683 	}
684 
685 	ikm_disable(monitor_name);
686 	ikm_destroy_trace_instance(inst);
687 
688 	if (config_reactor && config_initial_reactor)
689 		ikm_write_reactor(monitor_name, config_initial_reactor);
690 
691 	return 1;
692 
693 out_free_instance:
694 	ikm_destroy_trace_instance(inst);
695 	if (config_reactor && config_initial_reactor)
696 		ikm_write_reactor(monitor_name, config_initial_reactor);
697 	return -1;
698 }
699