xref: /openbmc/qemu/trace/control.c (revision 99d423e5) 
1 /*
2  * Interface for configuring and controlling the state of tracing events.
3  *
4  * Copyright (C) 2011-2016 Lluís Vilanova <vilanova@ac.upc.edu>
5  *
6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
7  * See the COPYING file in the top-level directory.
8  */
9 
10 #include "qemu/osdep.h"
11 #include "trace/control.h"
12 #include "qemu/help_option.h"
13 #include "qemu/option.h"
14 #ifdef CONFIG_TRACE_SIMPLE
15 #include "trace/simple.h"
16 #endif
17 #ifdef CONFIG_TRACE_FTRACE
18 #include "trace/ftrace.h"
19 #endif
20 #ifdef CONFIG_TRACE_LOG
21 #include "qemu/log.h"
22 #endif
23 #ifdef CONFIG_TRACE_SYSLOG
24 #include <syslog.h>
25 #endif
26 #include "qapi/error.h"
27 #include "qemu/error-report.h"
28 #include "qemu/config-file.h"
29 #include "monitor/monitor.h"
30 #include "trace-root.h"
31 
32 int trace_events_enabled_count;
33 
34 typedef struct TraceEventGroup {
35     TraceEvent **events;
36 } TraceEventGroup;
37 
38 static TraceEventGroup *event_groups;
39 static size_t nevent_groups;
40 static uint32_t next_id;
41 static uint32_t next_vcpu_id;
42 
43 QemuOptsList qemu_trace_opts = {
44     .name = "trace",
45     .implied_opt_name = "enable",
46     .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
47     .desc = {
48         {
49             .name = "enable",
50             .type = QEMU_OPT_STRING,
51         },
52         {
53             .name = "events",
54             .type = QEMU_OPT_STRING,
55         },{
56             .name = "file",
57             .type = QEMU_OPT_STRING,
58         },
59         { /* end of list */ }
60     },
61 };
62 
63 
64 void trace_event_register_group(TraceEvent **events)
65 {
66     size_t i;
67     for (i = 0; events[i] != NULL; i++) {
68         events[i]->id = next_id++;
69         if (events[i]->vcpu_id == TRACE_VCPU_EVENT_NONE) {
70             continue;
71         }
72 
73         if (likely(next_vcpu_id < CPU_TRACE_DSTATE_MAX_EVENTS)) {
74             events[i]->vcpu_id = next_vcpu_id++;
75         } else {
76             warn_report("too many vcpu trace events; dropping '%s'",
77                         events[i]->name);
78         }
79     }
80     event_groups = g_renew(TraceEventGroup, event_groups, nevent_groups + 1);
81     event_groups[nevent_groups].events = events;
82     nevent_groups++;
83 }
84 
85 
86 TraceEvent *trace_event_name(const char *name)
87 {
88     assert(name != NULL);
89 
90     TraceEventIter iter;
91     TraceEvent *ev;
92     trace_event_iter_init(&iter, NULL);
93     while ((ev = trace_event_iter_next(&iter)) != NULL) {
94         if (strcmp(trace_event_get_name(ev), name) == 0) {
95             return ev;
96         }
97     }
98     return NULL;
99 }
100 
101 static bool pattern_glob(const char *pat, const char *ev)
102 {
103     while (*pat != '\0' && *ev != '\0') {
104         if (*pat == *ev) {
105             pat++;
106             ev++;
107         }
108         else if (*pat == '*') {
109             if (pattern_glob(pat, ev+1)) {
110                 return true;
111             } else if (pattern_glob(pat+1, ev)) {
112                 return true;
113             } else {
114                 return false;
115             }
116         } else {
117             return false;
118         }
119     }
120 
121     while (*pat == '*') {
122         pat++;
123     }
124 
125     if (*pat == '\0' && *ev == '\0') {
126         return true;
127     } else {
128         return false;
129     }
130 }
131 
132 
133 void trace_event_iter_init(TraceEventIter *iter, const char *pattern)
134 {
135     iter->event = 0;
136     iter->group = 0;
137     iter->pattern = pattern;
138 }
139 
140 TraceEvent *trace_event_iter_next(TraceEventIter *iter)
141 {
142     while (iter->group < nevent_groups &&
143            event_groups[iter->group].events[iter->event] != NULL) {
144         TraceEvent *ev = event_groups[iter->group].events[iter->event];
145         iter->event++;
146         if (event_groups[iter->group].events[iter->event] == NULL) {
147             iter->event = 0;
148             iter->group++;
149         }
150         if (!iter->pattern ||
151             pattern_glob(iter->pattern,
152                          trace_event_get_name(ev))) {
153             return ev;
154         }
155     }
156 
157     return NULL;
158 }
159 
160 void trace_list_events(void)
161 {
162     TraceEventIter iter;
163     TraceEvent *ev;
164     trace_event_iter_init(&iter, NULL);
165     while ((ev = trace_event_iter_next(&iter)) != NULL) {
166         fprintf(stderr, "%s\n", trace_event_get_name(ev));
167     }
168 }
169 
170 static void do_trace_enable_events(const char *line_buf)
171 {
172     const bool enable = ('-' != line_buf[0]);
173     const char *line_ptr = enable ? line_buf : line_buf + 1;
174     TraceEventIter iter;
175     TraceEvent *ev;
176     bool is_pattern = trace_event_is_pattern(line_ptr);
177 
178     trace_event_iter_init(&iter, line_ptr);
179     while ((ev = trace_event_iter_next(&iter)) != NULL) {
180         if (!trace_event_get_state_static(ev)) {
181             if (!is_pattern) {
182                 warn_report("trace event '%s' is not traceable",
183                             line_ptr);
184                 return;
185             }
186             continue;
187         }
188 
189         /* start tracing */
190         trace_event_set_state_dynamic(ev, enable);
191         if (!is_pattern) {
192             return;
193         }
194     }
195 
196     if (!is_pattern) {
197         warn_report("trace event '%s' does not exist",
198                     line_ptr);
199     }
200 }
201 
202 void trace_enable_events(const char *line_buf)
203 {
204     if (is_help_option(line_buf)) {
205         trace_list_events();
206         if (cur_mon == NULL) {
207             exit(0);
208         }
209     } else {
210         do_trace_enable_events(line_buf);
211     }
212 }
213 
214 static void trace_init_events(const char *fname)
215 {
216     Location loc;
217     FILE *fp;
218     char line_buf[1024];
219     size_t line_idx = 0;
220 
221     if (fname == NULL) {
222         return;
223     }
224 
225     loc_push_none(&loc);
226     loc_set_file(fname, 0);
227     fp = fopen(fname, "r");
228     if (!fp) {
229         error_report("%s", strerror(errno));
230         exit(1);
231     }
232     while (fgets(line_buf, sizeof(line_buf), fp)) {
233         loc_set_file(fname, ++line_idx);
234         size_t len = strlen(line_buf);
235         if (len > 1) {              /* skip empty lines */
236             line_buf[len - 1] = '\0';
237             if ('#' == line_buf[0]) { /* skip commented lines */
238                 continue;
239             }
240             trace_enable_events(line_buf);
241         }
242     }
243     if (fclose(fp) != 0) {
244         loc_set_file(fname, 0);
245         error_report("%s", strerror(errno));
246         exit(1);
247     }
248     loc_pop(&loc);
249 }
250 
251 void trace_init_file(const char *file)
252 {
253 #ifdef CONFIG_TRACE_SIMPLE
254     st_set_trace_file(file);
255 #elif defined CONFIG_TRACE_LOG
256     /* If both the simple and the log backends are enabled, "--trace file"
257      * only applies to the simple backend; use "-D" for the log backend.
258      */
259     if (file) {
260         qemu_set_log_filename(file, &error_fatal);
261     }
262 #else
263     if (file) {
264         fprintf(stderr, "error: --trace file=...: "
265                 "option not supported by the selected tracing backends\n");
266         exit(1);
267     }
268 #endif
269 }
270 
271 void trace_fini_vcpu(CPUState *vcpu)
272 {
273     TraceEventIter iter;
274     TraceEvent *ev;
275 
276     trace_guest_cpu_exit(vcpu);
277 
278     trace_event_iter_init(&iter, NULL);
279     while ((ev = trace_event_iter_next(&iter)) != NULL) {
280         if (trace_event_is_vcpu(ev) &&
281             trace_event_get_state_static(ev) &&
282             trace_event_get_vcpu_state_dynamic(vcpu, ev)) {
283             /* must disable to affect the global counter */
284             trace_event_set_vcpu_state_dynamic(vcpu, ev, false);
285         }
286     }
287 }
288 
289 bool trace_init_backends(void)
290 {
291 #ifdef CONFIG_TRACE_SIMPLE
292     if (!st_init()) {
293         fprintf(stderr, "failed to initialize simple tracing backend.\n");
294         return false;
295     }
296 #endif
297 
298 #ifdef CONFIG_TRACE_FTRACE
299     if (!ftrace_init()) {
300         fprintf(stderr, "failed to initialize ftrace backend.\n");
301         return false;
302     }
303 #endif
304 
305 #ifdef CONFIG_TRACE_SYSLOG
306     openlog(NULL, LOG_PID, LOG_DAEMON);
307 #endif
308 
309     return true;
310 }
311 
312 char *trace_opt_parse(const char *optarg)
313 {
314     char *trace_file;
315     QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
316                                              optarg, true);
317     if (!opts) {
318         exit(1);
319     }
320     if (qemu_opt_get(opts, "enable")) {
321         trace_enable_events(qemu_opt_get(opts, "enable"));
322     }
323     trace_init_events(qemu_opt_get(opts, "events"));
324     trace_file = g_strdup(qemu_opt_get(opts, "file"));
325     qemu_opts_del(opts);
326 
327     return trace_file;
328 }
329 
330 uint32_t trace_get_vcpu_event_count(void)
331 {
332     return next_vcpu_id;
333 }
334