1 files changed, 212 insertions, 0 deletions
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 89779eb84a07..9f2e8520b748 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -223,3 +223,215 @@ static __init int init_dynamic_event(void)
 	return 0;
 }
 fs_initcall(init_dynamic_event);
+
+/**
+ * dynevent_arg_add - Add an arg to a dynevent_cmd
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
+ * @arg: The argument to append to the current cmd
+ * @check_arg: An (optional) pointer to a function checking arg sanity
+ *
+ * Append an argument to a dynevent_cmd.  The argument string will be
+ * appended to the current cmd string, followed by a separator, if
+ * applicable.  Before the argument is added, the @check_arg function,
+ * if present, will be used to check the sanity of the current arg
+ * string.
+ *
+ * The cmd string and separator should be set using the
+ * dynevent_arg_init() before any arguments are added using this
+ * function.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int dynevent_arg_add(struct dynevent_cmd *cmd,
+		     struct dynevent_arg *arg,
+		     dynevent_check_arg_fn_t check_arg)
+{
+	int ret = 0;
+
+	if (check_arg) {
+		ret = check_arg(arg);
+		if (ret)
+			return ret;
+	}
+
+	ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
+	if (ret) {
+		pr_err("String is too long: %s%c\n", arg->str, arg->separator);
+		return -E2BIG;
+	}
+
+	return ret;
+}
+
+/**
+ * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
+ * @arg_pair: The argument pair to append to the current cmd
+ * @check_arg: An (optional) pointer to a function checking arg sanity
+ *
+ * Append an argument pair to a dynevent_cmd.  An argument pair
+ * consists of a left-hand-side argument and a right-hand-side
+ * argument separated by an operator, which can be whitespace, all
+ * followed by a separator, if applicable.  This can be used to add
+ * arguments of the form 'type variable_name;' or 'x+y'.
+ *
+ * The lhs argument string will be appended to the current cmd string,
+ * followed by an operator, if applicable, followd by the rhs string,
+ * followed finally by a separator, if applicable.  Before the
+ * argument is added, the @check_arg function, if present, will be
+ * used to check the sanity of the current arg strings.
+ *
+ * The cmd strings, operator, and separator should be set using the
+ * dynevent_arg_pair_init() before any arguments are added using this
+ * function.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
+			  struct dynevent_arg_pair *arg_pair,
+			  dynevent_check_arg_fn_t check_arg)
+{
+	int ret = 0;
+
+	if (check_arg) {
+		ret = check_arg(arg_pair);
+		if (ret)
+			return ret;
+	}
+
+	ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
+			     arg_pair->operator, arg_pair->rhs,
+			     arg_pair->separator);
+	if (ret) {
+		pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
+		       arg_pair->operator, arg_pair->rhs,
+		       arg_pair->separator);
+		return -E2BIG;
+	}
+
+	return ret;
+}
+
+/**
+ * dynevent_str_add - Add a string to a dynevent_cmd
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
+ * @str: The string to append to the current cmd
+ *
+ * Append a string to a dynevent_cmd.  The string will be appended to
+ * the current cmd string as-is, with nothing prepended or appended.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
+{
+	int ret = 0;
+
+	ret = seq_buf_puts(&cmd->seq, str);
+	if (ret) {
+		pr_err("String is too long: %s\n", str);
+		return -E2BIG;
+	}
+
+	return ret;
+}
+
+/**
+ * dynevent_cmd_init - Initialize a dynevent_cmd object
+ * @cmd: A pointer to the dynevent_cmd struct representing the cmd
+ * @buf: A pointer to the buffer to generate the command into
+ * @maxlen: The length of the buffer the command will be generated into
+ * @type: The type of the cmd, checked against further operations
+ * @run_command: The type-specific function that will actually run the command
+ *
+ * Initialize a dynevent_cmd.  A dynevent_cmd is used to build up and
+ * run dynamic event creation commands, such as commands for creating
+ * synthetic and kprobe events.  Before calling any of the functions
+ * used to build the command, a dynevent_cmd object should be
+ * instantiated and initialized using this function.
+ *
+ * The initialization sets things up by saving a pointer to the
+ * user-supplied buffer and its length via the @buf and @maxlen
+ * params, and by saving the cmd-specific @type and @run_command
+ * params which are used to check subsequent dynevent_cmd operations
+ * and actually run the command when complete.
+ */
+void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
+		       enum dynevent_type type,
+		       dynevent_create_fn_t run_command)
+{
+	memset(cmd, '\0', sizeof(*cmd));
+
+	seq_buf_init(&cmd->seq, buf, maxlen);
+	cmd->type = type;
+	cmd->run_command = run_command;
+}
+
+/**
+ * dynevent_arg_init - Initialize a dynevent_arg object
+ * @arg: A pointer to the dynevent_arg struct representing the arg
+ * @separator: An (optional) separator, appended after adding the arg
+ *
+ * Initialize a dynevent_arg object.  A dynevent_arg represents an
+ * object used to append single arguments to the current command
+ * string.  After the arg string is successfully appended to the
+ * command string, the optional @separator is appended.  If no
+ * separator was specified when initializing the arg, a space will be
+ * appended.
+ */
+void dynevent_arg_init(struct dynevent_arg *arg,
+		       char separator)
+{
+	memset(arg, '\0', sizeof(*arg));
+
+	if (!separator)
+		separator = ' ';
+	arg->separator = separator;
+}
+
+/**
+ * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
+ * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
+ * @operator: An (optional) operator, appended after adding the first arg
+ * @separator: An (optional) separator, appended after adding the second arg
+ *
+ * Initialize a dynevent_arg_pair object.  A dynevent_arg_pair
+ * represents an object used to append argument pairs such as 'type
+ * variable_name;' or 'x+y' to the current command string.  An
+ * argument pair consists of a left-hand-side argument and a
+ * right-hand-side argument separated by an operator, which can be
+ * whitespace, all followed by a separator, if applicable.  After the
+ * first arg string is successfully appended to the command string,
+ * the optional @operator is appended, followed by the second arg and
+ * and optional @separator.  If no separator was specified when
+ * initializing the arg, a space will be appended.
+ */
+void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
+			    char operator, char separator)
+{
+	memset(arg_pair, '\0', sizeof(*arg_pair));
+
+	if (!operator)
+		operator = ' ';
+	arg_pair->operator = operator;
+
+	if (!separator)
+		separator = ' ';
+	arg_pair->separator = separator;
+}
+
+/**
+ * dynevent_create - Create the dynamic event contained in dynevent_cmd
+ * @cmd: The dynevent_cmd object containing the dynamic event creation command
+ *
+ * Once a dynevent_cmd object has been successfully built up via the
+ * dynevent_cmd_init(), dynevent_arg_add() and dynevent_arg_pair_add()
+ * functions, this function runs the final command to actually create
+ * the event.
+ *
+ * Return: 0 if the event was successfully created, error otherwise.
+ */
+int dynevent_create(struct dynevent_cmd *cmd)
+{
+	return cmd->run_command(cmd);
+}
+EXPORT_SYMBOL_GPL(dynevent_create);