diff options
Diffstat (limited to 'kernel/trace/trace_dynevent.c')
| -rw-r--r-- | kernel/trace/trace_dynevent.c | 483 |
1 files changed, 483 insertions, 0 deletions
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c new file mode 100644 index 000000000..4376887e0 --- /dev/null +++ b/kernel/trace/trace_dynevent.c @@ -0,0 +1,483 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Generic dynamic event control interface + * + * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org> + */ + +#include <linux/debugfs.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/mm.h> +#include <linux/mutex.h> +#include <linux/tracefs.h> + +#include "trace.h" +#include "trace_output.h" /* for trace_event_sem */ +#include "trace_dynevent.h" + +static DEFINE_MUTEX(dyn_event_ops_mutex); +static LIST_HEAD(dyn_event_ops_list); + +bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call) +{ + struct trace_event_call *call; + bool ret = false; + + if (WARN_ON_ONCE(!(dyn_call->flags & TRACE_EVENT_FL_DYNAMIC))) + return false; + + down_read(&trace_event_sem); + list_for_each_entry(call, &ftrace_events, list) { + if (call == dyn_call) { + atomic_inc(&dyn_call->refcnt); + ret = true; + } + } + up_read(&trace_event_sem); + return ret; +} + +void trace_event_dyn_put_ref(struct trace_event_call *call) +{ + if (WARN_ON_ONCE(!(call->flags & TRACE_EVENT_FL_DYNAMIC))) + return; + + if (WARN_ON_ONCE(atomic_read(&call->refcnt) <= 0)) { + atomic_set(&call->refcnt, 0); + return; + } + + atomic_dec(&call->refcnt); +} + +bool trace_event_dyn_busy(struct trace_event_call *call) +{ + return atomic_read(&call->refcnt) != 0; +} + +int dyn_event_register(struct dyn_event_operations *ops) +{ + if (!ops || !ops->create || !ops->show || !ops->is_busy || + !ops->free || !ops->match) + return -EINVAL; + + INIT_LIST_HEAD(&ops->list); + mutex_lock(&dyn_event_ops_mutex); + list_add_tail(&ops->list, &dyn_event_ops_list); + mutex_unlock(&dyn_event_ops_mutex); + return 0; +} + +int dyn_event_release(const char *raw_command, struct dyn_event_operations *type) +{ + struct dyn_event *pos, *n; + char *system = NULL, *event, *p; + int argc, ret = -ENOENT; + char **argv; + + argv = argv_split(GFP_KERNEL, raw_command, &argc); + if (!argv) + return -ENOMEM; + + if (argv[0][0] == '-') { + if (argv[0][1] != ':') { + ret = -EINVAL; + goto out; + } + event = &argv[0][2]; + } else { + event = strchr(argv[0], ':'); + if (!event) { + ret = -EINVAL; + goto out; + } + event++; + } + + p = strchr(event, '/'); + if (p) { + system = event; + event = p + 1; + *p = '\0'; + } + if (!system && event[0] == '\0') { + ret = -EINVAL; + goto out; + } + + mutex_lock(&event_mutex); + for_each_dyn_event_safe(pos, n) { + if (type && type != pos->ops) + continue; + if (!pos->ops->match(system, event, + argc - 1, (const char **)argv + 1, pos)) + continue; + + ret = pos->ops->free(pos); + if (ret) + break; + } + tracing_reset_all_online_cpus(); + mutex_unlock(&event_mutex); +out: + argv_free(argv); + return ret; +} + +static int create_dyn_event(const char *raw_command) +{ + struct dyn_event_operations *ops; + int ret = -ENODEV; + + if (raw_command[0] == '-' || raw_command[0] == '!') + return dyn_event_release(raw_command, NULL); + + mutex_lock(&dyn_event_ops_mutex); + list_for_each_entry(ops, &dyn_event_ops_list, list) { + ret = ops->create(raw_command); + if (!ret || ret != -ECANCELED) + break; + } + mutex_unlock(&dyn_event_ops_mutex); + if (ret == -ECANCELED) + ret = -EINVAL; + + return ret; +} + +/* Protected by event_mutex */ +LIST_HEAD(dyn_event_list); + +void *dyn_event_seq_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&event_mutex); + return seq_list_start(&dyn_event_list, *pos); +} + +void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos) +{ + return seq_list_next(v, &dyn_event_list, pos); +} + +void dyn_event_seq_stop(struct seq_file *m, void *v) +{ + mutex_unlock(&event_mutex); +} + +static int dyn_event_seq_show(struct seq_file *m, void *v) +{ + struct dyn_event *ev = v; + + if (ev && ev->ops) + return ev->ops->show(m, ev); + + return 0; +} + +static const struct seq_operations dyn_event_seq_op = { + .start = dyn_event_seq_start, + .next = dyn_event_seq_next, + .stop = dyn_event_seq_stop, + .show = dyn_event_seq_show +}; + +/* + * dyn_events_release_all - Release all specific events + * @type: the dyn_event_operations * which filters releasing events + * + * This releases all events which ->ops matches @type. If @type is NULL, + * all events are released. + * Return -EBUSY if any of them are in use, and return other errors when + * it failed to free the given event. Except for -EBUSY, event releasing + * process will be aborted at that point and there may be some other + * releasable events on the list. + */ +int dyn_events_release_all(struct dyn_event_operations *type) +{ + struct dyn_event *ev, *tmp; + int ret = 0; + + mutex_lock(&event_mutex); + for_each_dyn_event(ev) { + if (type && ev->ops != type) + continue; + if (ev->ops->is_busy(ev)) { + ret = -EBUSY; + goto out; + } + } + for_each_dyn_event_safe(ev, tmp) { + if (type && ev->ops != type) + continue; + ret = ev->ops->free(ev); + if (ret) + break; + } +out: + tracing_reset_all_online_cpus(); + mutex_unlock(&event_mutex); + + return ret; +} + +static int dyn_event_open(struct inode *inode, struct file *file) +{ + int ret; + + ret = tracing_check_open_get_tr(NULL); + if (ret) + return ret; + + if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) { + ret = dyn_events_release_all(NULL); + if (ret < 0) + return ret; + } + + return seq_open(file, &dyn_event_seq_op); +} + +static ssize_t dyn_event_write(struct file *file, const char __user *buffer, + size_t count, loff_t *ppos) +{ + return trace_parse_run_command(file, buffer, count, ppos, + create_dyn_event); +} + +static const struct file_operations dynamic_events_ops = { + .owner = THIS_MODULE, + .open = dyn_event_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, + .write = dyn_event_write, +}; + +/* Make a tracefs interface for controlling dynamic events */ +static __init int init_dynamic_event(void) +{ + int ret; + + ret = tracing_init_dentry(); + if (ret) + return 0; + + trace_create_file("dynamic_events", TRACE_MODE_WRITE, NULL, + NULL, &dynamic_events_ops); + + 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, followed 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 + * 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); |