X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Flttng-event-notifier-notification.c;h=ecbc0676291c4e9f425cdbbb86ad1ea37656c04a;hb=HEAD;hp=bd08991b745ff217749e58f026494b7026a34b2e;hpb=21f58fb7e62071dae3ddf13817631749bcab4e00;p=lttng-modules.git

diff --git a/src/lttng-event-notifier-notification.c b/src/lttng-event-notifier-notification.c
index bd08991b..29d2d156 100644
--- a/src/lttng-event-notifier-notification.c
+++ b/src/lttng-event-notifier-notification.c
@@ -5,31 +5,537 @@
  * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
  */
 
+#include <asm/barrier.h>
+#include <linux/bug.h>
+
+#include <lttng/lttng-bytecode.h>
 #include <lttng/events.h>
+#include <lttng/msgpack.h>
 #include <lttng/event-notifier-notification.h>
+#include <lttng/events-internal.h>
+#include <lttng/probe-user.h>
+
+/*
+ * The capture buffer size needs to be below 1024 bytes to avoid the
+ * frame to be larger than the 1024 limit enforced by the kernel. If we
+ * ever need to increase it, we will need to use a memory allocation
+ * scheme which allows allocating temporary memory chunks from the
+ * instrumentation sites. This could be done by adapting lttng
+ * tp-mempool to become nmi-safe and lock-free.
+ */
+#define CAPTURE_BUFFER_SIZE 512
+
+#define MSG_WRITE_NIL_LEN 1
+
+struct lttng_event_notifier_notification {
+	int notification_fd;
+	uint64_t event_notifier_token;
+	uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
+	struct lttng_msgpack_writer writer;
+	bool has_captures;
+};
+
+static
+int capture_enum(struct lttng_msgpack_writer *writer,
+		struct lttng_interpreter_output *output)
+{
+	int ret;
+
+	/*
+	 * Enums are captured as a map containing 2 key-value pairs. Such as:
+	 * - type: enum
+	 *   value: 177
+	 */
+	ret = lttng_msgpack_begin_map(writer, 2);
+	if (ret) {
+		goto end;
+	}
+
+	ret = lttng_msgpack_write_str(writer, "type");
+	if (ret) {
+		goto end;
+	}
+
+	ret = lttng_msgpack_write_str(writer, "enum");
+	if (ret) {
+		goto end;
+	}
+
+	ret = lttng_msgpack_write_str(writer, "value");
+	if (ret) {
+		goto end;
+	}
+
+	switch (output->type) {
+	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
+		ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
+		if (ret) {
+			goto end;
+		}
+		break;
+	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
+		ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
+		if (ret) {
+			goto end;
+		}
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_msgpack_end_map(writer);
+end:
+	return ret;
+}
+
+static
+int capture_sequence_element_signed(uint8_t *ptr,
+		const struct lttng_kernel_type_integer *type,
+		int64_t *_value)
+{
+	int64_t value = 0;
+	unsigned int size = type->size;
+	bool user = type->user;
+	bool byte_order_reversed = type->reverse_byte_order;
+
+	switch (size) {
+	case 8:
+	{
+		int8_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int8_t)))
+				return -1;
+		} else {
+			tmp = *ptr;
+		}
+		value = tmp;
+		break;
+	}
+	case 16:
+	{
+		int16_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int16_t)))
+				return -1;
+		} else {
+			tmp = *(int16_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab16s(&tmp);
+		value = tmp;
+		break;
+	}
+	case 32:
+	{
+		int32_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int32_t)))
+				return -1;
+		} else {
+			tmp = *(int32_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab32s(&tmp);
+		value = tmp;
+		break;
+	}
+	case 64:
+	{
+		int64_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int64_t)))
+				return -1;
+		} else {
+			tmp = *(int64_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab64s(&tmp);
+		value = tmp;
+		break;
+	}
+	default:
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	*_value = value;
+	return 0;
+}
+
+static
+int capture_sequence_element_unsigned(uint8_t *ptr,
+		const struct lttng_kernel_type_integer *type,
+		uint64_t *_value)
+{
+	uint64_t value = 0;
+	unsigned int size = type->size;
+	bool user = type->user;
+	bool byte_order_reversed = type->reverse_byte_order;
+
+	switch (size) {
+	case 8:
+	{
+		uint8_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint8_t)))
+				return -1;
+		} else {
+			tmp = *ptr;
+		}
+		value = tmp;
+		break;
+	}
+	case 16:
+	{
+		uint16_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint16_t)))
+				return -1;
+		} else {
+			tmp = *(uint16_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab16s(&tmp);
+		value = tmp;
+		break;
+	}
+	case 32:
+	{
+		uint32_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint32_t)))
+				return -1;
+		} else {
+			tmp = *(uint32_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab32s(&tmp);
+		value = tmp;
+		break;
+	}
+	case 64:
+	{
+		uint64_t tmp;
+
+		if (user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint64_t)))
+				return -1;
+		} else {
+			tmp = *(uint64_t *) ptr;
+		}
+		if (byte_order_reversed)
+			__swab64s(&tmp);
+		value = tmp;
+		break;
+	}
+	default:
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	*_value = value;
+	return 0;
+}
+
+static
+int capture_sequence(struct lttng_msgpack_writer *writer,
+		struct lttng_interpreter_output *output)
+{
+	const struct lttng_kernel_type_integer *integer_type = NULL;
+	const struct lttng_kernel_type_common *nested_type;
+	uint8_t *ptr;
+	bool signedness;
+	int ret, i;
+
+	ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
+	if (ret) {
+		goto end;
+	}
+
+	ptr = (uint8_t *) output->u.sequence.ptr;
+	nested_type = output->u.sequence.nested_type;
+	switch (nested_type->type) {
+	case lttng_kernel_type_integer:
+		integer_type = lttng_kernel_get_type_integer(nested_type);
+		break;
+	case lttng_kernel_type_enum:
+		/* Treat enumeration as an integer. */
+		integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
+		break;
+	default:
+		/* Capture of array of non-integer are not supported. */
+		WARN_ON_ONCE(1);
+		ret = -1;
+		goto end;
+	}
+	signedness = integer_type->signedness;
+	for (i = 0; i < output->u.sequence.nr_elem; i++) {
+		if (signedness) {
+			int64_t v;
 
-void lttng_event_notifier_notification_send(struct lttng_event_notifier *event_notifier)
+			ret = capture_sequence_element_signed(ptr, integer_type, &v);
+			if (ret) {
+				goto end;
+			}
+			ret = lttng_msgpack_write_signed_integer(writer, v);
+			if (ret) {
+				goto end;
+			}
+		} else {
+			uint64_t v;
+
+			ret = capture_sequence_element_unsigned(ptr, integer_type, &v);
+			if (ret) {
+				goto end;
+			}
+			ret = lttng_msgpack_write_unsigned_integer(writer, v);
+			if (ret) {
+				goto end;
+			}
+		}
+
+		/*
+		 * We assume that alignment is smaller or equal to the size.
+		 * This currently holds true but if it changes in the future,
+		 * we will want to change the pointer arithmetics below to
+		 * take into account that the next element might be further
+		 * away.
+		 */
+		WARN_ON_ONCE(integer_type->alignment > integer_type->size);
+
+		/* Size is in number of bits. */
+		ptr += (integer_type->size / CHAR_BIT) ;
+	}
+
+	ret = lttng_msgpack_end_array(writer);
+end:
+	return ret;
+}
+
+static
+int notification_append_capture(
+		struct lttng_event_notifier_notification *notif,
+		struct lttng_interpreter_output *output)
 {
-	struct lttng_event_notifier_group *event_notifier_group = event_notifier->group;
-	struct lib_ring_buffer_ctx ctx;
+	struct lttng_msgpack_writer *writer = &notif->writer;
+	int ret = 0;
+
+	switch (output->type) {
+	case LTTNG_INTERPRETER_TYPE_S64:
+		ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
+		break;
+	case LTTNG_INTERPRETER_TYPE_U64:
+		ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
+		break;
+	case LTTNG_INTERPRETER_TYPE_STRING:
+		if (output->u.str.user) {
+			ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
+		} else {
+			ret = lttng_msgpack_write_str(writer, output->u.str.str);
+		}
+		break;
+	case LTTNG_INTERPRETER_TYPE_SEQUENCE:
+		ret = capture_sequence(writer, output);
+		break;
+	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
+	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
+		ret = capture_enum(writer, output);
+		break;
+	default:
+		ret = -1;
+		WARN_ON_ONCE(1);
+	}
+	return ret;
+}
+
+static
+int notification_append_empty_capture(
+		struct lttng_event_notifier_notification *notif)
+{
+	return lttng_msgpack_write_nil(&notif->writer);
+}
+
+static
+int notification_init(struct lttng_event_notifier_notification *notif,
+		struct lttng_kernel_event_notifier *event_notifier)
+{
+	struct lttng_msgpack_writer *writer = &notif->writer;
+	int ret = 0;
+
+	notif->has_captures = false;
+
+	if (event_notifier->priv->num_captures > 0) {
+		lttng_msgpack_writer_init(writer, notif->capture_buf,
+				CAPTURE_BUFFER_SIZE);
+
+		ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
+		if (ret) {
+			goto end;
+		}
+
+		notif->has_captures = true;
+	}
+
+end:
+	return ret;
+}
+
+static
+void record_error(struct lttng_kernel_event_notifier *event_notifier)
+{
+
+	struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
+	struct lttng_counter *error_counter;
+	size_t dimension_index[1];
 	int ret;
 
-	if (unlikely(!READ_ONCE(event_notifier->enabled)))
+	/*
+	 * smp_load_acquire paired with smp_store_release orders creation of
+	 * the error counter and setting error_counter_len before the
+	 * error_counter is used.
+	 */
+	error_counter = smp_load_acquire(&event_notifier_group->error_counter);
+	/* This group may not have an error counter attached to it. */
+	if (!error_counter)
 		return;
 
-	lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, NULL,
-			sizeof(event_notifier->user_token),
-			lttng_alignof(event_notifier->user_token), -1);
-	ret = event_notifier_group->ops->event_reserve(&ctx, 0);
-	if (ret < 0) {
-		//TODO: error handling with counter maps
-		//silently drop for now.
+	dimension_index[0] = event_notifier->priv->error_counter_index;
+
+	ret = error_counter->ops->counter_add(error_counter->counter,
+			dimension_index, 1);
+	if (ret)
 		WARN_ON_ONCE(1);
+}
+
+static
+void notification_send(struct lttng_event_notifier_notification *notif,
+		struct lttng_kernel_event_notifier *event_notifier)
+{
+	struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
+	struct lttng_kernel_ring_buffer_ctx ctx;
+	struct lttng_kernel_abi_event_notifier_notification kernel_notif;
+	size_t capture_buffer_content_len, reserve_size;
+	int ret;
+
+	reserve_size = sizeof(kernel_notif);
+	kernel_notif.token = event_notifier->priv->parent.user_token;
+
+	if (notif->has_captures) {
+		capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
+	} else {
+		capture_buffer_content_len = 0;
+	}
+
+	WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
+
+	reserve_size += capture_buffer_content_len;
+	kernel_notif.capture_buf_size = capture_buffer_content_len;
+
+	lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
+			lttng_alignof(kernel_notif), NULL);
+	ret = event_notifier_group->ops->event_reserve(&ctx);
+	if (ret < 0) {
+		record_error(event_notifier);
 		return;
 	}
-	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(event_notifier->user_token));
-	event_notifier_group->ops->event_write(&ctx, &event_notifier->user_token,
-			sizeof(event_notifier->user_token));
+
+	/* Write the notif structure. */
+	event_notifier_group->ops->event_write(&ctx, &kernel_notif,
+			sizeof(kernel_notif), lttng_alignof(kernel_notif));
+
+	/*
+	 * Write the capture buffer. No need to realigned as the below is a raw
+	 * char* buffer.
+	 */
+	event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
+			capture_buffer_content_len, 1);
+
 	event_notifier_group->ops->event_commit(&ctx);
 	irq_work_queue(&event_notifier_group->wakeup_pending);
 }
+
+/*
+ * Validate that the buffer has enough room to hold empty capture fields.
+ */
+static
+bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
+{
+	if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
+		return false;
+	return true;
+}
+
+void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
+		const char *stack_data,
+		struct lttng_kernel_probe_ctx *probe_ctx,
+		struct lttng_kernel_notification_ctx *notif_ctx)
+{
+	struct lttng_event_notifier_notification notif = { 0 };
+	size_t captures_left;
+
+	if (notification_init(&notif, event_notifier))
+		goto error;
+
+	captures_left = event_notifier->priv->num_captures;
+	if (!validate_buffer_len(&notif, captures_left))
+		goto error;
+
+	if (unlikely(notif_ctx->eval_capture)) {
+		struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
+
+		/*
+		 * Iterate over all the capture bytecodes. If the interpreter
+		 * functions returns successfully, append the value of the
+		 * `output` parameter to the capture buffer. If the interpreter
+		 * fails, append an empty capture to the buffer.
+		 */
+		list_for_each_entry_rcu(capture_bc_runtime,
+				&event_notifier->priv->capture_bytecode_runtime_head, node) {
+			struct lttng_interpreter_output output;
+			uint8_t *save_pos;
+			int ret = -1;
+
+			lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
+			captures_left--;
+			if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
+					stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
+				ret = notification_append_capture(&notif, &output);
+			if (ret || !validate_buffer_len(&notif, captures_left)) {
+				/*
+				 * On append capture error or if the generated
+				 * buffer data would not leave enough room to
+				 * write empty capture fields for the remaining
+				 * fields, skip the field capture by restoring
+				 * the msgpack writer position and writing an
+				 * empty capture field.
+				 */
+				lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
+				ret = notification_append_empty_capture(&notif);
+				WARN_ON_ONCE(ret);
+			}
+		}
+	}
+
+	if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
+		goto error;
+
+	/*
+	 * Send the notification (including the capture buffer) to the
+	 * sessiond.
+	 */
+	notification_send(&notif, event_notifier);
+	return;
+
+error:
+	record_error(event_notifier);
+	return;
+}