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