xref: /openbmc/qemu/trace/control.c (revision ab9056ff) 
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 #ifdef CONFIG_TRACE_DTRACE
169     fprintf(stderr, "This list of names of trace points may be incomplete "
170                     "when using the DTrace/SystemTap backends.\n"
171                     "Run 'qemu-trace-stap list %s' to print the full list.\n",
172             error_get_progname());
173 #endif
174 }
175 
176 static void do_trace_enable_events(const char *line_buf)
177 {
178     const bool enable = ('-' != line_buf[0]);
179     const char *line_ptr = enable ? line_buf : line_buf + 1;
180     TraceEventIter iter;
181     TraceEvent *ev;
182     bool is_pattern = trace_event_is_pattern(line_ptr);
183 
184     trace_event_iter_init(&iter, line_ptr);
185     while ((ev = trace_event_iter_next(&iter)) != NULL) {
186         if (!trace_event_get_state_static(ev)) {
187             if (!is_pattern) {
188                 warn_report("trace event '%s' is not traceable",
189                             line_ptr);
190                 return;
191             }
192             continue;
193         }
194 
195         /* start tracing */
196         trace_event_set_state_dynamic(ev, enable);
197         if (!is_pattern) {
198             return;
199         }
200     }
201 
202     if (!is_pattern) {
203         warn_report("trace event '%s' does not exist",
204                     line_ptr);
205     }
206 }
207 
208 void trace_enable_events(const char *line_buf)
209 {
210     if (is_help_option(line_buf)) {
211         trace_list_events();
212         if (cur_mon == NULL) {
213             exit(0);
214         }
215     } else {
216         do_trace_enable_events(line_buf);
217     }
218 }
219 
220 static void trace_init_events(const char *fname)
221 {
222     Location loc;
223     FILE *fp;
224     char line_buf[1024];
225     size_t line_idx = 0;
226 
227     if (fname == NULL) {
228         return;
229     }
230 
231     loc_push_none(&loc);
232     loc_set_file(fname, 0);
233     fp = fopen(fname, "r");
234     if (!fp) {
235         error_report("%s", strerror(errno));
236         exit(1);
237     }
238     while (fgets(line_buf, sizeof(line_buf), fp)) {
239         loc_set_file(fname, ++line_idx);
240         size_t len = strlen(line_buf);
241         if (len > 1) {              /* skip empty lines */
242             line_buf[len - 1] = '\0';
243             if ('#' == line_buf[0]) { /* skip commented lines */
244                 continue;
245             }
246             trace_enable_events(line_buf);
247         }
248     }
249     if (fclose(fp) != 0) {
250         loc_set_file(fname, 0);
251         error_report("%s", strerror(errno));
252         exit(1);
253     }
254     loc_pop(&loc);
255 }
256 
257 void trace_init_file(const char *file)
258 {
259 #ifdef CONFIG_TRACE_SIMPLE
260     st_set_trace_file(file);
261 #elif defined CONFIG_TRACE_LOG
262     /* If both the simple and the log backends are enabled, "--trace file"
263      * only applies to the simple backend; use "-D" for the log backend.
264      */
265     if (file) {
266         qemu_set_log_filename(file, &error_fatal);
267     }
268 #else
269     if (file) {
270         fprintf(stderr, "error: --trace file=...: "
271                 "option not supported by the selected tracing backends\n");
272         exit(1);
273     }
274 #endif
275 }
276 
277 void trace_fini_vcpu(CPUState *vcpu)
278 {
279     TraceEventIter iter;
280     TraceEvent *ev;
281 
282     trace_guest_cpu_exit(vcpu);
283 
284     trace_event_iter_init(&iter, NULL);
285     while ((ev = trace_event_iter_next(&iter)) != NULL) {
286         if (trace_event_is_vcpu(ev) &&
287             trace_event_get_state_static(ev) &&
288             trace_event_get_vcpu_state_dynamic(vcpu, ev)) {
289             /* must disable to affect the global counter */
290             trace_event_set_vcpu_state_dynamic(vcpu, ev, false);
291         }
292     }
293 }
294 
295 bool trace_init_backends(void)
296 {
297 #ifdef CONFIG_TRACE_SIMPLE
298     if (!st_init()) {
299         fprintf(stderr, "failed to initialize simple tracing backend.\n");
300         return false;
301     }
302 #endif
303 
304 #ifdef CONFIG_TRACE_FTRACE
305     if (!ftrace_init()) {
306         fprintf(stderr, "failed to initialize ftrace backend.\n");
307         return false;
308     }
309 #endif
310 
311 #ifdef CONFIG_TRACE_SYSLOG
312     openlog(NULL, LOG_PID, LOG_DAEMON);
313 #endif
314 
315     return true;
316 }
317 
318 char *trace_opt_parse(const char *optarg)
319 {
320     char *trace_file;
321     QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
322                                              optarg, true);
323     if (!opts) {
324         exit(1);
325     }
326     if (qemu_opt_get(opts, "enable")) {
327         trace_enable_events(qemu_opt_get(opts, "enable"));
328     }
329     trace_init_events(qemu_opt_get(opts, "events"));
330     trace_file = g_strdup(qemu_opt_get(opts, "file"));
331     qemu_opts_del(opts);
332 
333     return trace_file;
334 }
335 
336 uint32_t trace_get_vcpu_event_count(void)
337 {
338     return next_vcpu_id;
339 }
340