Commit 369bc18f authored by Stefan Assmann's avatar Stefan Assmann Committed by Frederic Weisbecker
Browse files

ftrace: add kernel command line graph function filtering 



Add a command line parameter to allow limiting the function graphs
that are traced on boot up from the given top-level callers , when
ftrace=function_graph is specified.

This patch adds the following command line option:
ftrace_graph_filter=function-list

Where function-list is a comma separated list of functions to filter.

[fweisbec@gmail.com: picked the documentation changes from the v2 patch]

Signed-off-by: default avatarStefan Assmann <sassmann@redhat.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4AD2DEB9.2@redhat.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 3c355863

Documentation/kernel-parameters.txt

+7 −0
Original line number Diff line number Diff line
@@ -778,6 +778,13 @@ and is between 256 and 4096 characters. It is defined in the file 
			by the set_ftrace_notrace file in the debugfs

			tracing directory.



	ftrace_graph_filter=[function-list]

			[FTRACE] Limit the top level callers functions traced

			by the function graph tracer at boot up.

			function-list is a comma separated list of functions

			that can be changed at run time by the

			set_graph_function file in the debugfs tracing directory.



	gamecon.map[2|3]=

			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad

			support via parallel port (up to 5 devices per port)

kernel/trace/ftrace.c

+34 −0
Original line number Diff line number Diff line
@@ -78,6 +78,10 @@ ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; 
ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;

ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static int ftrace_set_func(unsigned long *array, int *idx, char *buffer);

#endif



static void ftrace_list_func(unsigned long ip, unsigned long parent_ip)

{

	struct ftrace_ops *op = ftrace_list;
@@ -2248,6 +2252,7 @@ void ftrace_set_notrace(unsigned char *buf, int len, int reset) 
#define FTRACE_FILTER_SIZE		COMMAND_LINE_SIZE

static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata;

static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;

static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;



static int __init set_ftrace_notrace(char *str)

{
@@ -2263,6 +2268,31 @@ static int __init set_ftrace_filter(char *str) 
}

__setup("ftrace_filter=", set_ftrace_filter);



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static int __init set_graph_function(char *str)

{

	strncpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);

	return 1;

}

__setup("ftrace_graph_filter=", set_graph_function);



static void __init set_ftrace_early_graph(char *buf)

{

	int ret;

	char *func;



	while (buf) {

		func = strsep(&buf, ",");

		/* we allow only one expression at a time */

		ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,

				      func);

		if (ret)

			printk(KERN_DEBUG "ftrace: function %s not "

					  "traceable\n", func);

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



static void __init set_ftrace_early_filter(char *buf, int enable)

{

	char *func;
@@ -2279,6 +2309,10 @@ static void __init set_ftrace_early_filters(void) 
		set_ftrace_early_filter(ftrace_filter_buf, 1);

	if (ftrace_notrace_buf[0])

		set_ftrace_early_filter(ftrace_notrace_buf, 0);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	if (ftrace_graph_buf[0])

		set_ftrace_early_graph(ftrace_graph_buf);

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

}



static int

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