Add --userspace-probe kernel event type
[lttng-tools.git] / src / bin / lttng / commands / enable_events.c
index f4403c25e8d30a566553dd40f23ff61d5f63504d..62f99a1fcfc760e659a3ab1c3a0e775fc79dccec 100644 (file)
@@ -54,6 +54,7 @@ static int opt_log4j;
 static int opt_python;
 static int opt_enable_all;
 static char *opt_probe;
+static char *opt_userspace_probe;
 static char *opt_function;
 static char *opt_channel_name;
 static char *opt_filter;
@@ -69,6 +70,7 @@ enum {
        OPT_HELP = 1,
        OPT_TRACEPOINT,
        OPT_PROBE,
+       OPT_USERSPACE_PROBE,
        OPT_FUNCTION,
        OPT_SYSCALL,
        OPT_USERSPACE,
@@ -95,6 +97,7 @@ static struct poptOption long_options[] = {
        {"python",         'p', POPT_ARG_VAL, &opt_python, 1, 0, 0},
        {"tracepoint",     0,   POPT_ARG_NONE, 0, OPT_TRACEPOINT, 0, 0},
        {"probe",          0,   POPT_ARG_STRING, &opt_probe, OPT_PROBE, 0, 0},
+       {"userspace-probe",0,   POPT_ARG_STRING, &opt_userspace_probe, OPT_USERSPACE_PROBE, 0, 0},
        {"function",       0,   POPT_ARG_STRING, &opt_function, OPT_FUNCTION, 0, 0},
        {"syscall",        0,   POPT_ARG_NONE, 0, OPT_SYSCALL, 0, 0},
        {"loglevel",       0,     POPT_ARG_STRING, 0, OPT_LOGLEVEL, 0, 0},
@@ -287,6 +290,214 @@ end:
        return ret;
 }
 
+/*
+ * Parse userspace probe options
+ * Set the userspace probe fields in the lttng_event struct and set the
+ * target_path to the path to the binary.
+ */
+static int parse_userspace_probe_opts(struct lttng_event *ev, char *opt)
+{
+       int ret = CMD_SUCCESS;
+       int num_token;
+       char **tokens;
+       char *target_path = NULL;
+       char *unescaped_target_path = NULL;
+       char *real_target_path = NULL;
+       char *symbol_name = NULL, *probe_name = NULL, *provider_name = NULL;
+       struct lttng_userspace_probe_location *probe_location = NULL;
+       struct lttng_userspace_probe_location_lookup_method *lookup_method =
+                       NULL;
+
+       if (opt == NULL) {
+               ret = CMD_ERROR;
+               goto end;
+       }
+
+       /*
+        * userspace probe fields are separated by ':'.
+        */
+       tokens = strutils_split(opt, ':', 1);
+       num_token = strutils_array_of_strings_len(tokens);
+
+       /*
+        * Early sanity check that the number of parameter is between 2 and 4
+        * inclusively.
+        * elf:PATH:SYMBOL
+        * std:PATH:PROVIDER_NAME:PROBE_NAME
+        * PATH:SYMBOL (same behavior as ELF)
+        */
+       if (num_token < 2 || num_token > 4) {
+               ret = CMD_ERROR;
+               goto end_string;
+       }
+
+       /*
+        * Looking up the first parameter will tell the technique to use to
+        * interpret the userspace probe/function description.
+        */
+       switch (num_token) {
+       case 2:
+               /* When the probe type is omitted we assume ELF for now. */
+       case 3:
+               if (num_token == 3 && strcmp(tokens[0], "elf") == 0) {
+                       target_path = tokens[1];
+                       symbol_name = tokens[2];
+               } else if (num_token == 2) {
+                       target_path = tokens[0];
+                       symbol_name = tokens[1];
+               } else {
+                       ret = CMD_ERROR;
+                       goto end_string;
+               }
+               lookup_method =
+                       lttng_userspace_probe_location_lookup_method_function_elf_create();
+               if (!lookup_method) {
+                       WARN("Failed to create ELF lookup method");
+                       ret = CMD_ERROR;
+                       goto end_string;
+               }
+               break;
+       case 4:
+               if (strcmp(tokens[0], "sdt") == 0) {
+                       target_path = tokens[1];
+                       provider_name = tokens[2];
+                       probe_name = tokens[3];
+               } else {
+                       ret = CMD_ERROR;
+                       goto end_string;
+               }
+               lookup_method =
+                       lttng_userspace_probe_location_lookup_method_tracepoint_sdt_create();
+               if (!lookup_method) {
+                       WARN("Failed to create ELF lookup method");
+                       ret = CMD_ERROR;
+                       goto end_string;
+               }
+               break;
+       default:
+               ret = CMD_ERROR;
+               goto end_string;
+       }
+
+       /* strutils_unescape_string allocates a new char *. */
+       unescaped_target_path = strutils_unescape_string(target_path, 0);
+       if (!unescaped_target_path) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end_string;
+       }
+
+       /*
+        * If there is not forward slash in the path. Walk the $PATH else
+        * expand.
+        */
+       if (strchr(target_path, '/') == NULL) {
+               /* Walk the $PATH variable to find the targeted binary. */
+               real_target_path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
+               if (!real_target_path) {
+                       PERROR("Error allocating path buffer");
+                       ret = CMD_ERROR;
+                       goto end_unescaped_string;
+               }
+               ret = walk_command_search_path(target_path, real_target_path);
+               if (ret) {
+                       ERR("Binary not found.");
+                       ret = CMD_ERROR;
+                       goto end_free_path;
+               }
+       } else {
+               /*
+                * Expand references to `/./` and `/../`. This function does not check
+                * if the file exists.
+                */
+               real_target_path = utils_expand_path_keep_symlink(target_path);
+               if (!real_target_path) {
+                       ERR("Error expanding the path to binary.");
+                       ret = CMD_ERROR;
+                       goto end_free_path;
+               }
+
+               /*
+                * Check if the file exists using access(2). If it does not, walk the
+                * $PATH.
+                */
+               ret = access(real_target_path, F_OK);
+               if (ret) {
+                       ret = CMD_ERROR;
+                       goto end_free_path;
+               }
+       }
+
+       switch (lttng_userspace_probe_location_lookup_method_get_type(lookup_method)) {
+       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
+               probe_location = lttng_userspace_probe_location_function_create(
+                               real_target_path, symbol_name, lookup_method);
+               if (!probe_location) {
+                       WARN("Failed to create function probe location");
+                       ret = CMD_ERROR;
+                       goto end_destroy_lookup_method;
+               }
+
+               /* Ownership transferred to probe_location. */
+               lookup_method = NULL;
+
+               ret = lttng_event_set_userspace_probe_location(ev, probe_location);
+               if (ret) {
+                       WARN("Failed to set probe location on event");
+                       ret = CMD_ERROR;
+                       goto end_destroy_location;
+               }
+               break;
+       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
+               probe_location = lttng_userspace_probe_location_tracepoint_create(
+                               real_target_path, provider_name, probe_name, lookup_method);
+               if (!probe_location) {
+                       WARN("Failed to create function probe location");
+                       ret = CMD_ERROR;
+                       goto end_destroy_lookup_method;
+               }
+
+               /* Ownership transferred to probe_location. */
+               lookup_method = NULL;
+
+               ret = lttng_event_set_userspace_probe_location(ev, probe_location);
+               if (ret) {
+                       WARN("Failed to set probe location on event");
+                       ret = CMD_ERROR;
+                       goto end_destroy_location;
+               }
+               break;
+       default:
+               ret = CMD_ERROR;
+               goto end_string;
+       }
+
+       switch (ev->type) {
+       case LTTNG_EVENT_USERSPACE_PROBE:
+               break;
+       default:
+               assert(0);
+       }
+
+       goto end;
+
+end_destroy_location:
+       lttng_userspace_probe_location_destroy(probe_location);
+end_destroy_lookup_method:
+       lttng_userspace_probe_location_lookup_method_destroy(lookup_method);
+end_free_path:
+       /*
+        * Free path that was allocated by the call to realpath() or when walking
+        * the PATH.
+        */
+       free(real_target_path);
+end_unescaped_string:
+       free(unescaped_target_path);
+end_string:
+       strutils_free_null_terminated_array_of_strings(tokens);
+end:
+       return ret;
+}
+
 /*
  * Maps LOG4j loglevel from string to value
  */
@@ -1058,6 +1269,14 @@ static int enable_events(char *session_name)
                                        goto error;
                                }
                                break;
+                       case LTTNG_EVENT_USERSPACE_PROBE:
+                               ret = parse_userspace_probe_opts(ev, opt_userspace_probe);
+                               if (ret) {
+                                       ERR("Unable to parse userspace probe options");
+                                       ret = CMD_ERROR;
+                                       goto error;
+                               }
+                               break;
                        case LTTNG_EVENT_FUNCTION:
                                ret = parse_probe_opts(ev, opt_function);
                                if (ret) {
@@ -1092,6 +1311,7 @@ static int enable_events(char *session_name)
                        case LTTNG_EVENT_PROBE:
                        case LTTNG_EVENT_FUNCTION:
                        case LTTNG_EVENT_SYSCALL:
+                       case LTTNG_EVENT_USERSPACE_PROBE:
                        default:
                                ERR("Event type not available for user-space tracing");
                                ret = CMD_UNSUPPORTED;
@@ -1205,6 +1425,12 @@ static int enable_events(char *session_name)
                                        error = 1;
                                        break;
                                }
+                               case LTTNG_ERR_SDT_PROBE_SEMAPHORE:
+                                       ERR("SDT probes %s guarded by semaphores are not supported (channel %s, session %s)",
+                                                       event_name, print_channel_name(channel_name),
+                                                       session_name);
+                                       error = 1;
+                                       break;
                                default:
                                        ERR("Event %s%s: %s (channel %s, session %s)", event_name,
                                                        exclusion_string,
@@ -1404,6 +1630,9 @@ int cmd_enable_events(int argc, const char **argv)
                case OPT_PROBE:
                        opt_event_type = LTTNG_EVENT_PROBE;
                        break;
+               case OPT_USERSPACE_PROBE:
+                       opt_event_type = LTTNG_EVENT_USERSPACE_PROBE;
+                       break;
                case OPT_FUNCTION:
                        opt_event_type = LTTNG_EVENT_FUNCTION;
                        break;
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