SoW-2019-0002: Dynamic Snapshot
[lttng-tools.git] / src / bin / lttng-sessiond / kernel.c
index 4ee4bea64ff630abae9617624f86ce21cc87950d..646da3ba83affd3463a30dd7e2efb7a43b05535c 100644 (file)
 #include <sys/types.h>
 
 #include <common/common.h>
+#include <common/hashtable/utils.h>
 #include <common/trace-chunk.h>
 #include <common/kernel-ctl/kernel-ctl.h>
 #include <common/kernel-ctl/kernel-ioctl.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 
+#include <lttng/userspace-probe.h>
+#include <lttng/userspace-probe-internal.h>
+#include <lttng/condition/event-rule.h>
+#include <lttng/condition/event-rule-internal.h>
+#include <lttng/event-rule/event-rule.h>
+#include <lttng/event-rule/event-rule-internal.h>
+#include <lttng/event-rule/uprobe-internal.h>
+
 #include "lttng-sessiond.h"
 #include "lttng-syscall.h"
 #include "consumer.h"
@@ -29,6 +38,7 @@
 #include "utils.h"
 #include "rotate.h"
 #include "modprobe.h"
+#include "notification-thread-commands.h"
 
 /*
  * Key used to reference a channel between the sessiond and the consumer. This
@@ -39,9 +49,10 @@ static uint64_t next_kernel_channel_key;
 static const char *module_proc_lttng = "/proc/lttng";
 
 static int kernel_tracer_fd = -1;
+static int kernel_tracer_trigger_group_fd = -1;
+static int kernel_tracer_trigger_group_notification_fd = -1;
+static struct ltt_kernel_token_event_rule_list kernel_tracer_token_list;
 
-#include <lttng/userspace-probe.h>
-#include <lttng/userspace-probe-internal.h>
 /*
  * Add context on a kernel channel.
  *
@@ -213,6 +224,44 @@ error:
        return -1;
 }
 
+/*
+ * Create a kernel channel, register it to the kernel tracer and add it to the
+ * kernel session.
+ */
+static
+int kernel_create_trigger_group(int *trigger_group_fd)
+{
+       int ret;
+       int local_fd = -1;
+
+       assert(trigger_group_fd);
+
+       /* Kernel tracer channel creation */
+       ret = kernctl_create_trigger_group(kernel_tracer_fd);
+       if (ret < 0) {
+               PERROR("ioctl kernel create trigger group");
+               ret = -1;
+               goto error;
+       }
+
+       /* Store locally */
+       local_fd = ret;
+
+       /* Prevent fd duplication after execlp() */
+       ret = fcntl(local_fd, F_SETFD, FD_CLOEXEC);
+       if (ret < 0) {
+               PERROR("fcntl session fd");
+       }
+
+       DBG("Kernel trigger group created (fd: %d)",
+                       local_fd);
+       ret = 0;
+
+error:
+       *trigger_group_fd = local_fd;
+       return ret;
+}
+
 /*
  * Compute the offset of the instrumentation byte in the binary based on the
  * function probe location using the ELF lookup method.
@@ -224,7 +273,7 @@ error:
 static
 int extract_userspace_probe_offset_function_elf(
                const struct lttng_userspace_probe_location *probe_location,
-               struct ltt_kernel_session *session, uint64_t *offset)
+               uid_t uid, gid_t gid, uint64_t *offset)
 {
        int fd;
        int ret = 0;
@@ -261,8 +310,7 @@ int extract_userspace_probe_offset_function_elf(
                goto end;
        }
 
-       ret = run_as_extract_elf_symbol_offset(fd, symbol, session->uid,
-                       session->gid, offset);
+       ret = run_as_extract_elf_symbol_offset(fd, symbol, uid, gid, offset);
        if (ret < 0) {
                DBG("userspace probe offset calculation failed for "
                                "function %s", symbol);
@@ -286,7 +334,7 @@ end:
 static
 int extract_userspace_probe_offset_tracepoint_sdt(
                const struct lttng_userspace_probe_location *probe_location,
-               struct ltt_kernel_session *session, uint64_t **offsets,
+               uid_t uid, gid_t gid, uint64_t **offsets,
                uint32_t *offsets_count)
 {
        enum lttng_userspace_probe_location_lookup_method_type lookup_method_type;
@@ -332,7 +380,7 @@ int extract_userspace_probe_offset_tracepoint_sdt(
        }
 
        ret = run_as_extract_sdt_probe_offsets(fd, provider_name, probe_name,
-                       session->uid, session->gid, offsets, offsets_count);
+                       uid, gid, offsets, offsets_count);
        if (ret < 0) {
                DBG("userspace probe offset calculation failed for sdt "
                                "probe %s:%s", provider_name, probe_name);
@@ -353,29 +401,16 @@ end:
        return ret;
 }
 
-/*
- * Extract the offsets of the instrumentation point for the different lookup
- * methods.
- */
 static
-int userspace_probe_add_callsites(struct lttng_event *ev,
-                       struct ltt_kernel_session *session, int fd)
+int userspace_probe_add_callsite(
+               const struct lttng_userspace_probe_location *location,
+               uid_t uid, gid_t gid, int fd)
 {
        const struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL;
        enum lttng_userspace_probe_location_lookup_method_type type;
-       const struct lttng_userspace_probe_location *location = NULL;
        int ret;
 
-       assert(ev);
-       assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
-
-       location = lttng_event_get_userspace_probe_location(ev);
-       if (!location) {
-               ret = -1;
-               goto end;
-       }
-       lookup_method =
-                       lttng_userspace_probe_location_get_lookup_method(location);
+       lookup_method = lttng_userspace_probe_location_get_lookup_method(location);
        if (!lookup_method) {
                ret = -1;
                goto end;
@@ -388,7 +423,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
                struct lttng_kernel_event_callsite callsite;
                uint64_t offset;
 
-               ret = extract_userspace_probe_offset_function_elf(location, session, &offset);
+               ret = extract_userspace_probe_offset_function_elf(location,
+                               uid, gid, &offset);
                if (ret) {
                        ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
                        goto end;
@@ -397,8 +433,7 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
                callsite.u.uprobe.offset = offset;
                ret = kernctl_add_callsite(fd, &callsite);
                if (ret) {
-                       WARN("Adding callsite to userspace probe "
-                                       "event %s failed.", ev->name);
+                       WARN("Adding callsite to ELF userspace probe failed.");
                        ret = LTTNG_ERR_KERN_ENABLE_FAIL;
                        goto end;
                }
@@ -415,8 +450,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
                 * This call allocates the offsets buffer. This buffer must be freed
                 * by the caller
                 */
-               ret = extract_userspace_probe_offset_tracepoint_sdt(location, session,
-                               &offsets, &offsets_count);
+               ret = extract_userspace_probe_offset_tracepoint_sdt(location,
+                               uid, gid, &offsets, &offsets_count);
                if (ret) {
                        ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
                        goto end;
@@ -425,8 +460,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
                        callsite.u.uprobe.offset = offsets[i];
                        ret = kernctl_add_callsite(fd, &callsite);
                        if (ret) {
-                               WARN("Adding callsite to userspace probe "
-                                               "event %s failed.", ev->name);
+                               WARN("Adding callsite to SDT userspace probe "
+                                       "failed.");
                                ret = LTTNG_ERR_KERN_ENABLE_FAIL;
                                free(offsets);
                                goto end;
@@ -443,6 +478,71 @@ end:
        return ret;
 }
 
+/*
+ * Extract the offsets of the instrumentation point for the different lookup
+ * methods.
+ */
+static
+int userspace_probe_event_add_callsites(struct lttng_event *ev,
+                       struct ltt_kernel_session *session, int fd)
+{
+       const struct lttng_userspace_probe_location *location = NULL;
+       int ret;
+
+       assert(ev);
+       assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
+
+       location = lttng_event_get_userspace_probe_location(ev);
+       if (!location) {
+               ret = -1;
+               goto end;
+       }
+
+       ret = userspace_probe_add_callsite(location, session->uid, session->gid,
+               fd);
+       if (ret) {
+               WARN("Adding callsite to userspace probe event \"%s\" "
+                       "failed.", ev->name);
+       }
+
+end:
+       return ret;
+}
+
+/*
+ * Extract the offsets of the instrumentation point for the different lookup
+ * methods.
+ */
+static int userspace_probe_event_rule_add_callsites(
+               const struct lttng_event_rule *rule,
+               const struct lttng_credentials *creds,
+               int fd)
+{
+       const struct lttng_userspace_probe_location *location = NULL;
+       enum lttng_event_rule_status status;
+       int ret;
+
+       assert(rule);
+       assert(creds);
+       assert(lttng_event_rule_get_type(rule) == LTTNG_EVENT_RULE_TYPE_UPROBE);
+
+       status = lttng_event_rule_uprobe_get_location(rule, &location);
+       if (status != LTTNG_EVENT_RULE_STATUS_OK || !location) {
+               ret = -1;
+               goto end;
+       }
+
+       ret = userspace_probe_add_callsite(location, creds->uid, creds->gid,
+               fd);
+       if (ret) {
+               WARN("Adding callsite to userspace probe object %d"
+                       "failed.", fd);
+       }
+
+end:
+       return ret;
+}
+
 /*
  * Create a kernel event, enable it to the kernel tracer and add it to the
  * channel event list of the kernel session.
@@ -512,7 +612,8 @@ int kernel_create_event(struct lttng_event *ev,
        }
 
        if (ev->type == LTTNG_EVENT_USERSPACE_PROBE) {
-               ret = userspace_probe_add_callsites(ev, channel->session, event->fd);
+               ret = userspace_probe_event_add_callsites(ev, channel->session,
+                       event->fd);
                if (ret) {
                        goto add_callsite_error;
                }
@@ -669,6 +770,36 @@ error:
        return ret;
 }
 
+/*
+ * Disable a kernel trigger.
+ */
+int kernel_disable_token_event_rule(struct ltt_kernel_token_event_rule *event)
+{
+       int ret;
+
+       assert(event);
+
+       ret = kernctl_disable(event->fd);
+       if (ret < 0) {
+               switch (-ret) {
+               case EEXIST:
+                       ret = LTTNG_ERR_KERN_EVENT_EXIST;
+                       break;
+               default:
+                       PERROR("disable kernel event");
+                       break;
+               }
+               goto error;
+       }
+
+       event->enabled = 0;
+       DBG("Kernel trigger token %" PRIu64" disabled (fd: %d)", event->token, event->fd);
+
+       return 0;
+
+error:
+       return ret;
+}
 static struct lttng_tracker_list *get_id_tracker_list(
                struct ltt_kernel_session *session,
                enum lttng_tracker_type tracker_type)
@@ -1732,20 +1863,37 @@ int init_kernel_tracer(void)
        if (ret < 0) {
                goto error_modules;
        }
-
        if (ret < 1) {
                WARN("Kernel tracer does not support buffer monitoring. "
                        "The monitoring timer of channels in the kernel domain "
                        "will be set to 0 (disabled).");
        }
 
+       ret = kernel_create_trigger_group(&kernel_tracer_trigger_group_fd);
+       if (ret < 0) {
+               /* TODO: error handling if it is not supported etc. */
+               WARN("Failed trigger group creation");
+               kernel_tracer_trigger_group_fd = -1;
+               /* This is not fatal */
+       } else {
+               ret = kernel_create_trigger_group_notification_fd(&kernel_tracer_trigger_group_notification_fd);
+               if (ret < 0) {
+                       goto error_modules;
+               }
+       }
+
+       CDS_INIT_LIST_HEAD(&kernel_tracer_token_list.head);
+
        DBG("Kernel tracer fd %d", kernel_tracer_fd);
+       DBG("Kernel tracer trigger group fd %d", kernel_tracer_trigger_group_fd);
+       DBG("Kernel tracer trigger group notificationi fd %d", kernel_tracer_trigger_group_notification_fd);
 
        ret = syscall_init_table(kernel_tracer_fd);
        if (ret < 0) {
                ERR("Unable to populate syscall table. Syscall tracing won't "
                        "work for this session daemon.");
        }
+
        return 0;
 
 error_version:
@@ -1781,6 +1929,31 @@ void cleanup_kernel_tracer(void)
 {
        int ret;
 
+       struct ltt_kernel_token_event_rule *rule, *rtmp;
+        cds_list_for_each_entry_safe(rule, rtmp, &kernel_tracer_token_list.head, list) {
+               kernel_disable_token_event_rule(rule);
+               trace_kernel_destroy_token_event_rule(rule);
+       }
+
+       DBG2("Closing kernel trigger group notification fd");
+       if (kernel_tracer_trigger_group_notification_fd >= 0) {
+               ret = close(kernel_tracer_trigger_group_notification_fd);
+               if (ret) {
+                       PERROR("close");
+               }
+               kernel_tracer_trigger_group_notification_fd = -1;
+       }
+
+       /* TODO: do we iterate over the list to remove all token? */
+       DBG2("Closing kernel trigger group fd");
+       if (kernel_tracer_trigger_group_fd >= 0) {
+               ret = close(kernel_tracer_trigger_group_fd);
+               if (ret) {
+                       PERROR("close");
+               }
+               kernel_tracer_trigger_group_fd = -1;
+       }
+
        DBG2("Closing kernel fd");
        if (kernel_tracer_fd >= 0) {
                ret = close(kernel_tracer_fd);
@@ -1789,6 +1962,8 @@ void cleanup_kernel_tracer(void)
                }
                kernel_tracer_fd = -1;
        }
+
+       
        DBG("Unloading kernel modules");
        modprobe_remove_lttng_all();
        free(syscall_table);
@@ -1879,3 +2054,274 @@ end:
        rcu_read_unlock();
        return status;
 }
+
+enum lttng_error_code kernel_create_trigger_group_notification_fd(
+               int *trigger_group_notification_fd)
+{
+       enum lttng_error_code ret = LTTNG_OK;
+       int local_fd = -1;
+
+       assert(trigger_group_notification_fd);
+
+       ret = kernctl_create_trigger_group_notification_fd(kernel_tracer_trigger_group_fd);
+       if (ret < 0) {
+               PERROR("ioctl kernel create trigger group");
+               ret = -1;
+               goto error;
+       }
+
+       /* Store locally */
+       local_fd = ret;
+
+       /* Prevent fd duplication after execlp() */
+       ret = fcntl(local_fd, F_SETFD, FD_CLOEXEC);
+       if (ret < 0) {
+               PERROR("fcntl session fd");
+       }
+
+       DBG("Kernel trigger group notification created (fd: %d)",
+                       local_fd);
+       ret = 0;
+
+error:
+       *trigger_group_notification_fd = local_fd;
+       return ret;
+}
+
+enum lttng_error_code kernel_destroy_trigger_group_notification_fd(
+               int trigger_group_notification_fd)
+{
+       enum lttng_error_code ret = LTTNG_OK;
+       DBG("Closing trigger group notification fd %d", trigger_group_notification_fd);
+       if (trigger_group_notification_fd >= 0) {
+               ret = close(trigger_group_notification_fd);
+               if (ret) {
+                       PERROR("close");
+               }
+       }
+       return ret;
+}
+
+static int kernel_create_token_event_rule(struct lttng_event_rule *rule,
+               const struct lttng_credentials *creds, uint64_t token)
+{
+       int err, fd;
+       enum lttng_error_code ret;
+       struct ltt_kernel_token_event_rule *event;
+       struct lttng_kernel_trigger trigger;
+
+       assert(rule);
+
+       ret = trace_kernel_create_token_event_rule(rule, token, &event);
+       if (ret != LTTNG_OK) {
+               goto error;
+       }
+       
+       trace_kernel_init_trigger_from_event_rule(event->event_rule, &trigger);
+       trigger.id = event->token;
+
+       fd = kernctl_create_trigger(kernel_tracer_trigger_group_fd, &trigger);
+       if (fd < 0) {
+               switch (-fd) {
+               case EEXIST:
+                       ret = LTTNG_ERR_KERN_EVENT_EXIST;
+                       break;
+               case ENOSYS:
+                       WARN("Trigger type not implemented");
+                       ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
+                       break;
+               case ENOENT:
+                       WARN("Event %s not found!", trigger.name);
+                       ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+                       break;
+               default:
+                       ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+                       PERROR("create trigger ioctl");
+               }
+               goto free_event;
+       }
+
+       event->fd = fd;
+       /* Prevent fd duplication after execlp() */
+       err = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
+       if (err < 0) {
+               PERROR("fcntl session fd");
+       }
+
+       if (event->filter) {
+               err = kernctl_filter(event->fd, event->filter);
+               if (err < 0) {
+                       switch (-err) {
+                       case ENOMEM:
+                               ret = LTTNG_ERR_FILTER_NOMEM;
+                               break;
+                       default:
+                               ret = LTTNG_ERR_FILTER_INVAL;
+                               break;
+                       }
+                       goto filter_error;
+               }
+       }
+
+       if (lttng_event_rule_get_type(event->event_rule) ==
+                       LTTNG_EVENT_RULE_TYPE_UPROBE) {
+               ret = userspace_probe_event_rule_add_callsites(
+                               rule, creds, event->fd);
+               if (ret) {
+                       goto add_callsite_error;
+               }
+       }
+
+       err = kernctl_enable(event->fd);
+       if (err < 0) {
+               switch (-err) {
+               case EEXIST:
+                       ret = LTTNG_ERR_KERN_EVENT_EXIST;
+                       break;
+               default:
+                       PERROR("enable kernel trigger");
+                       ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+                       break;
+               }
+               goto enable_error;
+       }
+
+       /* Add event to event list */
+       cds_list_add(&event->list, &kernel_tracer_token_list.head);
+
+       DBG("Trigger %s created (fd: %d)", trigger.name, event->fd);
+
+       return 0;
+
+add_callsite_error:
+enable_error:
+filter_error:
+       {
+               int closeret;
+
+               closeret = close(event->fd);
+               if (closeret) {
+                       PERROR("close event fd");
+               }
+       }
+free_event:
+       free(event);
+error:
+       return ret;
+}
+
+enum lttng_error_code kernel_update_tokens(void)
+{
+       enum lttng_error_code ret = LTTNG_OK;
+       enum lttng_trigger_status t_status;
+       struct ltt_kernel_token_event_rule *token_event_rule_element;
+       struct lttng_triggers *triggers;
+       unsigned int count;
+       
+       /* TODO error handling */
+
+       /* Get list of token trigger from the notification thread here */
+       rcu_read_lock();
+       pthread_mutex_lock(&notification_trigger_tokens_ht_lock);
+       ret = notification_thread_command_get_tokens(notification_thread_handle, &triggers);
+       if (ret != LTTNG_OK) {
+               ret = -1;
+               goto end;
+       }
+
+       assert(triggers);
+
+       t_status = lttng_triggers_get_count(triggers, &count);
+       if (t_status != LTTNG_TRIGGER_STATUS_OK) {
+               ret = -1;
+               goto end;
+       }
+
+       for (unsigned int i = 0; i < count; i++) {
+               struct lttng_condition *condition;
+               struct lttng_event_rule *event_rule;
+               struct lttng_trigger *trigger;
+               struct ltt_kernel_token_event_rule *k_token;
+               const struct lttng_credentials *creds;
+               uint64_t token;
+
+               trigger = lttng_triggers_get_pointer_of_index(triggers, i);
+               assert(trigger);
+
+               /* TODO: error checking and type checking */
+               token = lttng_trigger_get_key(trigger);
+               condition = lttng_trigger_get_condition(trigger);
+               (void) lttng_condition_event_rule_get_rule_no_const(condition, &event_rule);
+
+               if (lttng_event_rule_get_domain_type(event_rule) != LTTNG_DOMAIN_KERNEL) {
+                       /* Skip ust related trigger */
+                       continue;
+               }
+
+               creds = lttng_trigger_get_credentials(trigger);
+               /* Iterate over all known token trigger */
+               k_token = trace_kernel_find_trigger_by_token(&kernel_tracer_token_list, token);
+               if (!k_token) {
+                       ret = kernel_create_token_event_rule(event_rule, creds, token);
+                       if (ret < 0) {
+                               goto end;
+                       }
+               }
+       }
+
+       /* Remove all unknown trigger from the app
+        * TODO find a way better way then this, do it on the unregister command
+        * and be specific on the token to remove instead of going over all
+        * trigger known to the app. This is sub optimal.
+        */
+       cds_list_for_each_entry (token_event_rule_element, &kernel_tracer_token_list.head,
+                       list) {
+               uint64_t token;
+               bool found = false;
+
+               token = token_event_rule_element->token;
+
+       /*
+                * Check if the app event trigger still exists on the
+                * notification side.
+                * TODO: might want to change the backing data struct of the
+                * lttng_triggers object to allow quick lookup?
+                * For kernel mostly all of this can be removed once we delete
+                * on a per trigger basis.
+                */
+
+               for (unsigned int i = 0; i < count; i++) {
+                       struct lttng_trigger *trigger;
+                       uint64_t inner_token;
+
+                       trigger = lttng_triggers_get_pointer_of_index(
+                                       triggers, i);
+                       assert(trigger);
+
+                       inner_token = lttng_trigger_get_key(trigger);
+
+                       if (inner_token == token) {
+                               found = true;
+                               break;
+                       }
+               }
+
+               if (found) {
+                       /* Still valid */
+                       continue;
+               }
+
+               kernel_disable_token_event_rule(token_event_rule_element);
+               trace_kernel_destroy_token_event_rule(token_event_rule_element);
+       }
+end:
+       rcu_read_unlock();
+       pthread_mutex_unlock(&notification_trigger_tokens_ht_lock);
+       return ret;
+
+}
+
+int kernel_get_notification_fd(void)
+{
+       return kernel_tracer_trigger_group_notification_fd;
+}
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