trace/control.c

   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 }