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Subject[PATCH 05/15] ftrace: add module command function filter selection
From: Steven Rostedt <srostedt@redhat.com>

This patch adds a "command" syntax to the function filtering files:

/debugfs/tracing/set_ftrace_filter
/debugfs/tracing/set_ftrace_notrace

Of the format: <function>:<command>:<parameter>

The command is optional, and dependent on the command, so are
the parameters.

echo do_fork > set_ftrace_filter

Will only trace 'do_fork'.

echo 'sched_*' > set_ftrace_filter

Will only trace functions starting with the letters 'sched_'.

echo '*:mod:ext3' > set_ftrace_filter

Will trace only the ext3 module functions.

echo '*write*:mod:ext3' > set_ftrace_notrace

Will prevent the ext3 functions with the letters 'write' in
the name from being traced.

echo '!*_allocate:mod:ext3' > set_ftrace_filter

Will remove the functions in ext3 that end with the letters
'_allocate' from the ftrace filter.

Although this patch implements the 'command' format, only the
'mod' command is supported. More commands to follow.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/ftrace.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 109 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index fcec313..9e60ae4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1067,7 +1067,7 @@ enum {
* 0 otherwise.
*/
static int
-ftrace_setup_glob(unsigned char *buff, int len, char **search, int *not)
+ftrace_setup_glob(char *buff, int len, char **search, int *not)
{
int type = MATCH_FULL;
int i;
@@ -1100,14 +1100,11 @@ ftrace_setup_glob(unsigned char *buff, int len, char **search, int *not)
return type;
}

-static int
-ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
+static int ftrace_match(char *str, char *regex, int len, int type)
{
- char str[KSYM_SYMBOL_LEN];
int matched = 0;
char *ptr;

- kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
switch (type) {
case MATCH_FULL:
if (strcmp(str, regex) == 0)
@@ -1131,6 +1128,15 @@ ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
return matched;
}

+static int
+ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
+{
+ char str[KSYM_SYMBOL_LEN];
+
+ kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+ return ftrace_match(str, regex, len, type);
+}
+
static void ftrace_match_records(char *buff, int len, int enable)
{
char *search;
@@ -1165,6 +1171,100 @@ static void ftrace_match_records(char *buff, int len, int enable)
spin_unlock(&ftrace_lock);
}

+static int
+ftrace_match_module_record(struct dyn_ftrace *rec, char *mod,
+ char *regex, int len, int type)
+{
+ char str[KSYM_SYMBOL_LEN];
+ char *modname;
+
+ kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
+
+ if (!modname || strcmp(modname, mod))
+ return 0;
+
+ /* blank search means to match all funcs in the mod */
+ if (len)
+ return ftrace_match(str, regex, len, type);
+ else
+ return 1;
+}
+
+static void ftrace_match_module_records(char *buff, char *mod, int enable)
+{
+ char *search = buff;
+ struct ftrace_page *pg;
+ struct dyn_ftrace *rec;
+ int type = MATCH_FULL;
+ unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
+ unsigned search_len = 0;
+ int not = 0;
+
+ /* blank or '*' mean the same */
+ if (strcmp(buff, "*") == 0)
+ buff[0] = 0;
+
+ /* handle the case of 'dont filter this module' */
+ if (strcmp(buff, "!") == 0 || strcmp(buff, "!*") == 0) {
+ buff[0] = 0;
+ not = 1;
+ }
+
+ if (strlen(buff)) {
+ type = ftrace_setup_glob(buff, strlen(buff), &search, &not);
+ search_len = strlen(search);
+ }
+
+ /* should not be called from interrupt context */
+ spin_lock(&ftrace_lock);
+ if (enable)
+ ftrace_filtered = 1;
+
+ do_for_each_ftrace_rec(pg, rec) {
+
+ if (rec->flags & FTRACE_FL_FAILED)
+ continue;
+
+ if (ftrace_match_module_record(rec, mod,
+ search, search_len, type)) {
+ if (not)
+ rec->flags &= ~flag;
+ else
+ rec->flags |= flag;
+ }
+
+ } while_for_each_ftrace_rec();
+ spin_unlock(&ftrace_lock);
+}
+
+static int ftrace_process_regex(char *buff, int len, int enable)
+{
+ char *func, *mod, *command, *next = buff;
+
+ func = strsep(&next, ":");
+
+ if (!next) {
+ ftrace_match_records(func, len, enable);
+ return 0;
+ }
+
+ /* command fonud */
+
+ 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;
+ }
+
+ return -EINVAL;
+}
+
static ssize_t
ftrace_regex_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos, int enable)
@@ -1232,7 +1332,10 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
if (isspace(ch)) {
iter->filtered++;
iter->buffer[iter->buffer_idx] = 0;
- ftrace_match_records(iter->buffer, iter->buffer_idx, enable);
+ ret = ftrace_process_regex(iter->buffer,
+ iter->buffer_idx, enable);
+ if (ret)
+ goto out;
iter->buffer_idx = 0;
} else
iter->flags |= FTRACE_ITER_CONT;
--
1.5.6.5
--


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