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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: Stefan Assmann <sassmann@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4AD2DEB9.2@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Stefan Assmann 2009-10-12 22:17:21 +02:00 committed by Frederic Weisbecker
parent 3c355863fb
commit 369bc18f9a
2 changed files with 41 additions and 0 deletions
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7
Documentation/kernel-parameters.txt
View File

@ -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)

34
kernel/trace/ftrace.c
View File

@ -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