userspace-probe: Decouple `userspace_probe_add_callsite()` from event and session
[lttng-tools.git] / src / bin / lttng-sessiond / kernel.c
index d7c7984d201ba96c82d050eb71a48dca798c8e38..1fc36e33e9b45b1c7b941c3261f7c8ad0c07dfe9 100644 (file)
@@ -230,7 +230,7 @@ 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;
@@ -267,8 +267,7 @@ 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);
@@ -292,7 +291,7 @@ 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;
@@ -338,7 +337,7 @@ 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);
@@ -359,29 +358,16 @@ 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;
@@ -394,7 +380,8 @@ 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;
@@ -403,8 +390,7 @@ 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("Failed to add callsite to ELF userspace probe.");
                        ret = LTTNG_ERR_KERN_ENABLE_FAIL;
                        goto end;
                }
@@ -421,8 +407,8 @@ 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;
@@ -431,8 +417,7 @@ 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("Failed to add callsite to SDT userspace probe");
                                ret = LTTNG_ERR_KERN_ENABLE_FAIL;
                                free(offsets);
                                goto end;
@@ -449,6 +434,37 @@ 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)
+{
+       int ret;
+       const struct lttng_userspace_probe_location *location = NULL;
+
+       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("Failed to add callsite to userspace probe event '%s'",
+                               ev->name);
+       }
+
+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.
@@ -518,7 +534,8 @@ 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;
                }
@@ -1641,16 +1658,10 @@ int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
        return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
 }
 
-/*
- * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
- * version number.
- *
- * Return 1 on success, 0 when feature is not supported, negative value in case
- * of errors.
- */
-int kernel_supports_ring_buffer_snapshot_sample_positions(void)
+static
+int kernel_tracer_abi_greater_or_equal(unsigned int major, unsigned int minor)
 {
-       int ret = 0; // Not supported by default
+       int ret;
        struct lttng_kernel_tracer_abi_version abi;
 
        ret = kernctl_tracer_abi_version(kernel_tracer_fd, &abi);
@@ -1659,18 +1670,24 @@ int kernel_supports_ring_buffer_snapshot_sample_positions(void)
                goto error;
        }
 
+       ret = abi.major > major || (abi.major == major && abi.minor >= minor);
+error:
+       return ret;
+}
+
+/*
+ * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
+ * version number.
+ *
+ * Return 1 on success, 0 when feature is not supported, negative value in case
+ * of errors.
+ */
+int kernel_supports_ring_buffer_snapshot_sample_positions(void)
+{
        /*
         * RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS was introduced in 2.3
         */
-       if (abi.major >= 2 && abi.minor >= 3) {
-               /* Supported */
-               ret = 1;
-       } else {
-               /* Not supported */
-               ret = 0;
-       }
-error:
-       return ret;
+       return kernel_tracer_abi_greater_or_equal(2, 3);
 }
 
 /*
@@ -1681,28 +1698,25 @@ error:
  */
 int kernel_supports_ring_buffer_packet_sequence_number(void)
 {
-       int ret = 0; // Not supported by default
-       struct lttng_kernel_tracer_abi_version abi;
-
-       ret = kernctl_tracer_abi_version(kernel_tracer_fd, &abi);
-       if (ret < 0) {
-               ERR("Failed to retrieve lttng-modules ABI version");
-               goto error;
-       }
-
        /*
         * Packet sequence number was introduced in LTTng 2.8,
         * lttng-modules ABI 2.1.
         */
-       if (abi.major >= 2 && abi.minor >= 1) {
-               /* Supported */
-               ret = 1;
-       } else {
-               /* Not supported */
-               ret = 0;
-       }
-error:
-       return ret;
+       return kernel_tracer_abi_greater_or_equal(2, 1);
+}
+
+/*
+ * Check for the support of event notifiers via abi version number.
+ *
+ * Return 1 on success, 0 when feature is not supported, negative value in case
+ * of errors.
+ */
+int kernel_supports_event_notifiers(void)
+{
+       /*
+        * Event notifiers were introduced in LTTng 2.13, lttng-modules ABI 2.6.
+        */
+       return kernel_tracer_abi_greater_or_equal(2, 6);
 }
 
 /*
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