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Subject[tip:perf/core] ftrace, perf: Add filter support for function trace event
Commit-ID:  5500fa51199aee770ce53718853732600543619e
Gitweb: http://git.kernel.org/tip/5500fa51199aee770ce53718853732600543619e
Author: Jiri Olsa <jolsa@redhat.com>
AuthorDate: Wed, 15 Feb 2012 15:51:54 +0100
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Tue, 21 Feb 2012 11:08:30 -0500

ftrace, perf: Add filter support for function trace event

Adding support to filter function trace event via perf
interface. It is now possible to use filter interface
in the perf tool like:

perf record -e ftrace:function --filter="(ip == mm_*)" ls

The filter syntax is restricted to the the 'ip' field only,
and following operators are accepted '==' '!=' '||', ending
up with the filter strings like:
ip == f1[, ]f2 ... || ip != f3[, ]f4 ...
with comma ',' or space ' ' as a function separator. If the
space ' ' is used as a separator, the right side of the
assignment needs to be enclosed in double quotes '"', e.g.:

perf record -e ftrace:function --filter '(ip == do_execve,sys_*,ext*)' ls
perf record -e ftrace:function --filter '(ip == "do_execve,sys_*,ext*")' ls
perf record -e ftrace:function --filter '(ip == "do_execve sys_* ext*")' ls

The '==' operator adds trace filter with same effect as would
be added via set_ftrace_filter file.

The '!=' operator adds trace filter with same effect as would
be added via set_ftrace_notrace file.

The right side of the '!=', '==' operators is list of functions
or regexp. to be added to filter separated by space.

The '||' operator is used for connecting multiple filter definitions
together. It is possible to have more than one '==' and '!='
operators within one filter string.
Link: http://lkml.kernel.org/r/1329317514-8131-8-git-send-email-jolsa@redhat.com

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ftrace.h | 7 +-
kernel/trace/ftrace.c | 6 ++
kernel/trace/trace.h | 2 -
kernel/trace/trace_event_perf.c | 4 +-
kernel/trace/trace_events_filter.c | 165 ++++++++++++++++++++++++++++++++++--
5 files changed, 172 insertions(+), 12 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 64a309d..72a6cab 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -250,6 +250,7 @@ int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
int len, int reset);
void ftrace_set_global_filter(unsigned char *buf, int len, int reset);
void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
+void ftrace_free_filter(struct ftrace_ops *ops);

int register_ftrace_command(struct ftrace_func_command *cmd);
int unregister_ftrace_command(struct ftrace_func_command *cmd);
@@ -380,9 +381,6 @@ extern void ftrace_enable_daemon(void);
#else
static inline int skip_trace(unsigned long ip) { return 0; }
static inline int ftrace_force_update(void) { return 0; }
-static inline void ftrace_set_filter(unsigned char *buf, int len, int reset)
-{
-}
static inline void ftrace_disable_daemon(void) { }
static inline void ftrace_enable_daemon(void) { }
static inline void ftrace_release_mod(struct module *mod) {}
@@ -406,6 +404,9 @@ static inline int ftrace_text_reserved(void *start, void *end)
*/
#define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
#define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
+#define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
+#define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
+#define ftrace_free_filter(ops) do { } while (0)

static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos) { return -ENODEV; }
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f615f97..867bd1d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1186,6 +1186,12 @@ static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
}

+void ftrace_free_filter(struct ftrace_ops *ops)
+{
+ free_ftrace_hash(ops->filter_hash);
+ free_ftrace_hash(ops->notrace_hash);
+}
+
static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
{
struct ftrace_hash *hash;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 29f93cd..54faec7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -776,9 +776,7 @@ struct filter_pred {
u64 val;
struct regex regex;
unsigned short *ops;
-#ifdef CONFIG_FTRACE_STARTUP_TEST
struct ftrace_event_field *field;
-#endif
int offset;
int not;
int op;
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index fdeeb5c..fee3752 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -298,7 +298,9 @@ static int perf_ftrace_function_register(struct perf_event *event)
static int perf_ftrace_function_unregister(struct perf_event *event)
{
struct ftrace_ops *ops = &event->ftrace_ops;
- return unregister_ftrace_function(ops);
+ int ret = unregister_ftrace_function(ops);
+ ftrace_free_filter(ops);
+ return ret;
}

static void perf_ftrace_function_enable(struct perf_event *event)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 3da3d0e..431dba8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -81,6 +81,7 @@ enum {
FILT_ERR_TOO_MANY_PREDS,
FILT_ERR_MISSING_FIELD,
FILT_ERR_INVALID_FILTER,
+ FILT_ERR_IP_FIELD_ONLY,
};

static char *err_text[] = {
@@ -96,6 +97,7 @@ static char *err_text[] = {
"Too many terms in predicate expression",
"Missing field name and/or value",
"Meaningless filter expression",
+ "Only 'ip' field is supported for function trace",
};

struct opstack_op {
@@ -991,7 +993,12 @@ static int init_pred(struct filter_parse_state *ps,
fn = filter_pred_strloc;
else
fn = filter_pred_pchar;
- } else if (!is_function_field(field)) {
+ } else if (is_function_field(field)) {
+ if (strcmp(field->name, "ip")) {
+ parse_error(ps, FILT_ERR_IP_FIELD_ONLY, 0);
+ return -EINVAL;
+ }
+ } else {
if (field->is_signed)
ret = strict_strtoll(pred->regex.pattern, 0, &val);
else
@@ -1338,10 +1345,7 @@ static struct filter_pred *create_pred(struct filter_parse_state *ps,

strcpy(pred.regex.pattern, operand2);
pred.regex.len = strlen(pred.regex.pattern);
-
-#ifdef CONFIG_FTRACE_STARTUP_TEST
pred.field = field;
-#endif
return init_pred(ps, field, &pred) ? NULL : &pred;
}

@@ -1954,6 +1958,148 @@ void ftrace_profile_free_filter(struct perf_event *event)
__free_filter(filter);
}

+struct function_filter_data {
+ struct ftrace_ops *ops;
+ int first_filter;
+ int first_notrace;
+};
+
+#ifdef CONFIG_FUNCTION_TRACER
+static char **
+ftrace_function_filter_re(char *buf, int len, int *count)
+{
+ char *str, *sep, **re;
+
+ str = kstrndup(buf, len, GFP_KERNEL);
+ if (!str)
+ return NULL;
+
+ /*
+ * The argv_split function takes white space
+ * as a separator, so convert ',' into spaces.
+ */
+ while ((sep = strchr(str, ',')))
+ *sep = ' ';
+
+ re = argv_split(GFP_KERNEL, str, count);
+ kfree(str);
+ return re;
+}
+
+static int ftrace_function_set_regexp(struct ftrace_ops *ops, int filter,
+ int reset, char *re, int len)
+{
+ int ret;
+
+ if (filter)
+ ret = ftrace_set_filter(ops, re, len, reset);
+ else
+ ret = ftrace_set_notrace(ops, re, len, reset);
+
+ return ret;
+}
+
+static int __ftrace_function_set_filter(int filter, char *buf, int len,
+ struct function_filter_data *data)
+{
+ int i, re_cnt, ret;
+ int *reset;
+ char **re;
+
+ reset = filter ? &data->first_filter : &data->first_notrace;
+
+ /*
+ * The 'ip' field could have multiple filters set, separated
+ * either by space or comma. We first cut the filter and apply
+ * all pieces separatelly.
+ */
+ re = ftrace_function_filter_re(buf, len, &re_cnt);
+ if (!re)
+ return -EINVAL;
+
+ for (i = 0; i < re_cnt; i++) {
+ ret = ftrace_function_set_regexp(data->ops, filter, *reset,
+ re[i], strlen(re[i]));
+ if (ret)
+ break;
+
+ if (*reset)
+ *reset = 0;
+ }
+
+ argv_free(re);
+ return ret;
+}
+
+static int ftrace_function_check_pred(struct filter_pred *pred, int leaf)
+{
+ struct ftrace_event_field *field = pred->field;
+
+ if (leaf) {
+ /*
+ * Check the leaf predicate for function trace, verify:
+ * - only '==' and '!=' is used
+ * - the 'ip' field is used
+ */
+ if ((pred->op != OP_EQ) && (pred->op != OP_NE))
+ return -EINVAL;
+
+ if (strcmp(field->name, "ip"))
+ return -EINVAL;
+ } else {
+ /*
+ * Check the non leaf predicate for function trace, verify:
+ * - only '||' is used
+ */
+ if (pred->op != OP_OR)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int ftrace_function_set_filter_cb(enum move_type move,
+ struct filter_pred *pred,
+ int *err, void *data)
+{
+ /* Checking the node is valid for function trace. */
+ if ((move != MOVE_DOWN) ||
+ (pred->left != FILTER_PRED_INVALID)) {
+ *err = ftrace_function_check_pred(pred, 0);
+ } else {
+ *err = ftrace_function_check_pred(pred, 1);
+ if (*err)
+ return WALK_PRED_ABORT;
+
+ *err = __ftrace_function_set_filter(pred->op == OP_EQ,
+ pred->regex.pattern,
+ pred->regex.len,
+ data);
+ }
+
+ return (*err) ? WALK_PRED_ABORT : WALK_PRED_DEFAULT;
+}
+
+static int ftrace_function_set_filter(struct perf_event *event,
+ struct event_filter *filter)
+{
+ struct function_filter_data data = {
+ .first_filter = 1,
+ .first_notrace = 1,
+ .ops = &event->ftrace_ops,
+ };
+
+ return walk_pred_tree(filter->preds, filter->root,
+ ftrace_function_set_filter_cb, &data);
+}
+#else
+static int ftrace_function_set_filter(struct perf_event *event,
+ struct event_filter *filter)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_FUNCTION_TRACER */
+
int ftrace_profile_set_filter(struct perf_event *event, int event_id,
char *filter_str)
{
@@ -1974,9 +2120,16 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
goto out_unlock;

err = create_filter(call, filter_str, false, &filter);
- if (!err)
- event->filter = filter;
+ if (err)
+ goto free_filter;
+
+ if (ftrace_event_is_function(call))
+ err = ftrace_function_set_filter(event, filter);
else
+ event->filter = filter;
+
+free_filter:
+ if (err || ftrace_event_is_function(call))
__free_filter(filter);

out_unlock:

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