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Commit f6180773 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ftrace: add command interface for function selection 



Allow for other tracers to add their own commands for function
selection. This interface gives a trace the ability to name a
command for function selection. Right now it is pretty limited
in what it offers, but this is a building step for more features.

The :mod: command is converted to this interface and also serves
as a template for other implementations.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent e68746a2

include/linux/ftrace.h

+16 −0
Original line number Diff line number Diff line
@@ -95,6 +95,13 @@ stack_trace_sysctl(struct ctl_table *table, int write, 
		   loff_t *ppos);

#endif



struct ftrace_func_command {

	struct list_head	list;

	char			*name;

	int			(*func)(char *func, char *cmd,

					char *params, int enable);

};



#ifdef CONFIG_DYNAMIC_FTRACE

/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */

#include <asm/ftrace.h>
@@ -119,6 +126,9 @@ struct dyn_ftrace { 
int ftrace_force_update(void);

void ftrace_set_filter(unsigned char *buf, int len, int reset);



int register_ftrace_command(struct ftrace_func_command *cmd);

int unregister_ftrace_command(struct ftrace_func_command *cmd);



/* defined in arch */

extern int ftrace_ip_converted(unsigned long ip);

extern int ftrace_dyn_arch_init(void *data);
@@ -202,6 +212,12 @@ extern void ftrace_enable_daemon(void); 
# define ftrace_disable_daemon()		do { } while (0)

# define ftrace_enable_daemon()			do { } while (0)

static inline void ftrace_release(void *start, unsigned long size) { }

static inline int register_ftrace_command(struct ftrace_func_command *cmd)

{

}

static inline int unregister_ftrace_command(char *cmd_name)

{

}

#endif /* CONFIG_DYNAMIC_FTRACE */



/* totally disable ftrace - can not re-enable after this */

kernel/trace/ftrace.c

+95 −11
Original line number Diff line number Diff line
@@ -1239,9 +1239,93 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable) 
	spin_unlock(&ftrace_lock);

}



/*

 * We register the module command as a template to show others how

 * to register the a command as well.

 */



static int

ftrace_mod_callback(char *func, char *cmd, char *param, int enable)

{

	char *mod;



	/*

	 * cmd == 'mod' because we only registered this func

	 * for the 'mod' ftrace_func_command.

	 * But if you register one func with multiple commands,

	 * you can tell which command was used by the cmd

	 * parameter.

	 */



	/* we must have a module name */

	if (!param)

		return -EINVAL;



	mod = strsep(&param, ":");

	if (!strlen(mod))

		return -EINVAL;



	ftrace_match_module_records(func, mod, enable);

	return 0;

}



static struct ftrace_func_command ftrace_mod_cmd = {

	.name			= "mod",

	.func			= ftrace_mod_callback,

};



static int __init ftrace_mod_cmd_init(void)

{

	return register_ftrace_command(&ftrace_mod_cmd);

}

device_initcall(ftrace_mod_cmd_init);



static LIST_HEAD(ftrace_commands);

static DEFINE_MUTEX(ftrace_cmd_mutex);



int register_ftrace_command(struct ftrace_func_command *cmd)

{

	struct ftrace_func_command *p;

	int ret = 0;



	mutex_lock(&ftrace_cmd_mutex);

	list_for_each_entry(p, &ftrace_commands, list) {

		if (strcmp(cmd->name, p->name) == 0) {

			ret = -EBUSY;

			goto out_unlock;

		}

	}

	list_add(&cmd->list, &ftrace_commands);

 out_unlock:

	mutex_unlock(&ftrace_cmd_mutex);



	return ret;

}



int unregister_ftrace_command(struct ftrace_func_command *cmd)

{

	struct ftrace_func_command *p, *n;

	int ret = -ENODEV;



	mutex_lock(&ftrace_cmd_mutex);

	list_for_each_entry_safe(p, n, &ftrace_commands, list) {

		if (strcmp(cmd->name, p->name) == 0) {

			ret = 0;

			list_del_init(&p->list);

			goto out_unlock;

		}

	}

 out_unlock:

	mutex_unlock(&ftrace_cmd_mutex);



	return ret;

}



static int ftrace_process_regex(char *buff, int len, int enable)

{

	char *func, *mod, *command, *next = buff;

	struct ftrace_func_command *p;

	char *func, *command, *next = buff;

	int ret = -EINVAL;



	func = strsep(&next, ":");
@@ -1250,21 +1334,21 @@ static int ftrace_process_regex(char *buff, int len, int enable) 
		return 0;

	}



	/* command fonud */

	/* command found */



	command = strsep(&next, ":");



	if (strcmp(command, "mod") == 0) {

		/* only match modules */

		if (!next)

			return -EINVAL;



		mod = strsep(&next, ":");

		ftrace_match_module_records(func, mod, enable);

		return 0;

	mutex_lock(&ftrace_cmd_mutex);

	list_for_each_entry(p, &ftrace_commands, list) {

		if (strcmp(p->name, command) == 0) {

			ret = p->func(func, command, next, enable);

			goto out_unlock;

		}

	}

 out_unlock:

	mutex_unlock(&ftrace_cmd_mutex);



	return -EINVAL;

	return ret;

}



static ssize_t