xref: /qemu/trace/control.c (revision dc293f60) 
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/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 static bool init_trace_on_startup;
43 static char *trace_opts_file;
44 
45 QemuOptsList qemu_trace_opts = {
46     .name = "trace",
47     .implied_opt_name = "enable",
48     .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
49     .desc = {
50         {
51             .name = "enable",
52             .type = QEMU_OPT_STRING,
53         },
54         {
55             .name = "events",
56             .type = QEMU_OPT_STRING,
57         },{
58             .name = "file",
59             .type = QEMU_OPT_STRING,
60         },
61         { /* end of list */ }
62     },
63 };
64 
65 
66 void trace_event_register_group(TraceEvent **events)
67 {
68     size_t i;
69     for (i = 0; events[i] != NULL; i++) {
70         events[i]->id = next_id++;
71         if (events[i]->vcpu_id == TRACE_VCPU_EVENT_NONE) {
72             continue;
73         }
74 
75         if (likely(next_vcpu_id < CPU_TRACE_DSTATE_MAX_EVENTS)) {
76             events[i]->vcpu_id = next_vcpu_id++;
77         } else {
78             warn_report("too many vcpu trace events; dropping '%s'",
79                         events[i]->name);
80         }
81     }
82     event_groups = g_renew(TraceEventGroup, event_groups, nevent_groups + 1);
83     event_groups[nevent_groups].events = events;
84     nevent_groups++;
85 }
86 
87 
88 TraceEvent *trace_event_name(const char *name)
89 {
90     assert(name != NULL);
91 
92     TraceEventIter iter;
93     TraceEvent *ev;
94     trace_event_iter_init(&iter, NULL);
95     while ((ev = trace_event_iter_next(&iter)) != NULL) {
96         if (strcmp(trace_event_get_name(ev), name) == 0) {
97             return ev;
98         }
99     }
100     return NULL;
101 }
102 
103 void trace_event_iter_init(TraceEventIter *iter, const char *pattern)
104 {
105     iter->event = 0;
106     iter->group = 0;
107     iter->pattern = pattern;
108 }
109 
110 TraceEvent *trace_event_iter_next(TraceEventIter *iter)
111 {
112     while (iter->group < nevent_groups &&
113            event_groups[iter->group].events[iter->event] != NULL) {
114         TraceEvent *ev = event_groups[iter->group].events[iter->event];
115         iter->event++;
116         if (event_groups[iter->group].events[iter->event] == NULL) {
117             iter->event = 0;
118             iter->group++;
119         }
120         if (!iter->pattern ||
121             g_pattern_match_simple(iter->pattern, trace_event_get_name(ev))) {
122             return ev;
123         }
124     }
125 
126     return NULL;
127 }
128 
129 void trace_list_events(FILE *f)
130 {
131     TraceEventIter iter;
132     TraceEvent *ev;
133     trace_event_iter_init(&iter, NULL);
134     while ((ev = trace_event_iter_next(&iter)) != NULL) {
135         fprintf(f, "%s\n", trace_event_get_name(ev));
136     }
137 #ifdef CONFIG_TRACE_DTRACE
138     fprintf(f, "This list of names of trace points may be incomplete "
139                "when using the DTrace/SystemTap backends.\n"
140                "Run 'qemu-trace-stap list %s' to print the full list.\n",
141             error_get_progname());
142 #endif
143 }
144 
145 static void do_trace_enable_events(const char *line_buf)
146 {
147     const bool enable = ('-' != line_buf[0]);
148     const char *line_ptr = enable ? line_buf : line_buf + 1;
149     TraceEventIter iter;
150     TraceEvent *ev;
151     bool is_pattern = trace_event_is_pattern(line_ptr);
152 
153     trace_event_iter_init(&iter, line_ptr);
154     while ((ev = trace_event_iter_next(&iter)) != NULL) {
155         if (!trace_event_get_state_static(ev)) {
156             if (!is_pattern) {
157                 warn_report("trace event '%s' is not traceable",
158                             line_ptr);
159                 return;
160             }
161             continue;
162         }
163 
164         /* start tracing */
165         trace_event_set_state_dynamic(ev, enable);
166         if (!is_pattern) {
167             return;
168         }
169     }
170 
171     if (!is_pattern) {
172         warn_report("trace event '%s' does not exist",
173                     line_ptr);
174     }
175 }
176 
177 void trace_enable_events(const char *line_buf)
178 {
179     if (is_help_option(line_buf)) {
180         trace_list_events(stdout);
181         if (monitor_cur() == NULL) {
182             exit(0);
183         }
184     } else {
185         do_trace_enable_events(line_buf);
186     }
187 }
188 
189 static void trace_init_events(const char *fname)
190 {
191     Location loc;
192     FILE *fp;
193     char line_buf[1024];
194     size_t line_idx = 0;
195 
196     if (fname == NULL) {
197         return;
198     }
199 
200     loc_push_none(&loc);
201     loc_set_file(fname, 0);
202     fp = fopen(fname, "r");
203     if (!fp) {
204         error_report("%s", strerror(errno));
205         exit(1);
206     }
207     while (fgets(line_buf, sizeof(line_buf), fp)) {
208         loc_set_file(fname, ++line_idx);
209         size_t len = strlen(line_buf);
210         if (len > 1) {              /* skip empty lines */
211             line_buf[len - 1] = '\0';
212             if ('#' == line_buf[0]) { /* skip commented lines */
213                 continue;
214             }
215             trace_enable_events(line_buf);
216         }
217     }
218     if (fclose(fp) != 0) {
219         loc_set_file(fname, 0);
220         error_report("%s", strerror(errno));
221         exit(1);
222     }
223     loc_pop(&loc);
224 }
225 
226 void trace_init_file(void)
227 {
228 #ifdef CONFIG_TRACE_SIMPLE
229     st_set_trace_file(trace_opts_file);
230     if (init_trace_on_startup) {
231         st_set_trace_file_enabled(true);
232     }
233 #elif defined CONFIG_TRACE_LOG
234     /*
235      * If both the simple and the log backends are enabled, "--trace file"
236      * only applies to the simple backend; use "-D" for the log
237      * backend. However we should only override -D if we actually have
238      * something to override it with.
239      */
240     if (trace_opts_file) {
241         qemu_set_log_filename(trace_opts_file, &error_fatal);
242     }
243 #else
244     if (trace_opts_file) {
245         fprintf(stderr, "error: --trace file=...: "
246                 "option not supported by the selected tracing backends\n");
247         exit(1);
248     }
249 #endif
250 }
251 
252 void trace_fini_vcpu(CPUState *vcpu)
253 {
254     TraceEventIter iter;
255     TraceEvent *ev;
256 
257     trace_guest_cpu_exit(vcpu);
258 
259     trace_event_iter_init(&iter, NULL);
260     while ((ev = trace_event_iter_next(&iter)) != NULL) {
261         if (trace_event_is_vcpu(ev) &&
262             trace_event_get_state_static(ev) &&
263             trace_event_get_vcpu_state_dynamic(vcpu, ev)) {
264             /* must disable to affect the global counter */
265             trace_event_set_vcpu_state_dynamic(vcpu, ev, false);
266         }
267     }
268 }
269 
270 bool trace_init_backends(void)
271 {
272 #ifdef CONFIG_TRACE_SIMPLE
273     if (!st_init()) {
274         fprintf(stderr, "failed to initialize simple tracing backend.\n");
275         return false;
276     }
277 #endif
278 
279 #ifdef CONFIG_TRACE_FTRACE
280     if (!ftrace_init()) {
281         fprintf(stderr, "failed to initialize ftrace backend.\n");
282         return false;
283     }
284 #endif
285 
286 #ifdef CONFIG_TRACE_SYSLOG
287     openlog(NULL, LOG_PID, LOG_DAEMON);
288 #endif
289 
290     return true;
291 }
292 
293 void trace_opt_parse(const char *optarg)
294 {
295     QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
296                                              optarg, true);
297     if (!opts) {
298         exit(1);
299     }
300     if (qemu_opt_get(opts, "enable")) {
301         trace_enable_events(qemu_opt_get(opts, "enable"));
302     }
303     trace_init_events(qemu_opt_get(opts, "events"));
304     init_trace_on_startup = true;
305     g_free(trace_opts_file);
306     trace_opts_file = g_strdup(qemu_opt_get(opts, "file"));
307     qemu_opts_del(opts);
308 }
309 
310 uint32_t trace_get_vcpu_event_count(void)
311 {
312     return next_vcpu_id;
313 }
314