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
17static int config_has_id;
18static int config_my_pid;
19static int config_trace;
20
21static char *config_initial_reactor;
22static 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 */
32static 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 */
52static 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 */
72static 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 */
94static 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 */
104static 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 */
115static 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 */
137static 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 */
168static 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 */
186static 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 */
210static 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
239out_free:
240	free(reactors);
241
242	return curr_reactor;
243}
244
245static 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 */
273int 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
306static 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 */
337static int
338ikm_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 */
389static int
390ikm_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 */
431static 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
479out_inst:
480	trace_instance_destroy(inst);
481out_free:
482	free(inst);
483out_err:
484	return NULL;
485}
486
487/**
488 * ikm_destroy_trace_instance - destroy a previously created instance
489 */
490static 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 */
502static 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 */
529static 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 */
565static 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 */
633int 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
693out_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