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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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"
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 __free(argv_free) = argv_split(GFP_KERNEL, raw_command, &argc);
if (!argv) return -ENOMEM;
if (argv[0][0] == '-') { if (argv[0][1] != ':') return -EINVAL; event = &argv[0][2]; } else { event = strchr(argv[0], ':'); if (!event) return -EINVAL; event++; }
p = strchr(event, '/'); if (p) { system = event; event = p + 1; *p = '\0'; } if (!system && event[0] == '\0') return -EINVAL;
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); return ret;}
/* * Locked version of event creation. The event creation must be protected by * dyn_event_ops_mutex because of protecting trace_probe_log. */int dyn_event_create(const char *raw_command, struct dyn_event_operations *type){ int ret;
mutex_lock(&dyn_event_ops_mutex); ret = type->create(raw_command); mutex_unlock(&dyn_event_ops_mutex); 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; } if (ret == -ECANCELED) { static const char *err_msg[] = {"No matching dynamic event type"};
/* Wrong dynamic event. Leave an error message. */ tracing_log_err(NULL, "dynevent", raw_command, err_msg, 0, 0); ret = -EINVAL; }
mutex_unlock(&dyn_event_ops_mutex);
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 = security_locked_down(LOCKDOWN_TRACEFS); if (ret) return 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);