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 */
__ikm_read_enable(char * monitor_name)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 */
ikm_read_enable(char * monitor_name)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 */
ikm_write_enable(char * monitor_name,char * enable_disable)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 */
ikm_enable(char * monitor_name)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 */
ikm_disable(char * monitor_name)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 */
ikm_read_desc(char * monitor_name)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 */
ikm_fill_monitor_definition(char * name,struct monitor * ikm)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 */
ikm_write_reactor(char * monitor_name,char * reactor)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 */
ikm_read_reactor(char * monitor_name)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 */
ikm_get_current_reactor(char * monitor_name)210 static char *ikm_get_current_reactor(char *monitor_name)
211 {
212 char *reactors = ikm_read_reactor(monitor_name);
213 char *curr_reactor = NULL;
214 char *start;
215 char *end;
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
ikm_has_id(char * monitor_name)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 */
ikm_list_monitors(void)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
ikm_print_header(struct trace_seq * s)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 prints event.
336 */
337 static int
ikm_event_handler(struct trace_seq * s,struct tep_record * record,struct tep_event * trace_event,void * context)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 prints event.
388 */
389 static int
ikm_error_handler(struct trace_seq * s,struct tep_record * record,struct tep_event * trace_event,void * context)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 */
ikm_setup_trace_instance(char * monitor_name)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 */
ikm_destroy_trace_instance(struct trace_instance * inst)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 */
ikm_usage_print_reactors(void)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 */
ikm_usage(int exit_val,char * monitor_name,const char * fmt,...)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 */
parse_arguments(char * monitor_name,int argc,char ** argv)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 */
ikm_run_monitor(char * monitor_name,int argc,char ** argv)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