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Date: Mon, 28 Nov 2011 15:07:04 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Jiri Olsa <jolsa@...hat.com>
Cc: fweisbec@...il.com, mingo@...hat.com, paulus@...ba.org,
acme@...stprotocols.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 9/9] ftrace, perf: Add filter support for function
trace event
On Sun, 2011-11-27 at 19:04 +0100, Jiri Olsa wrote:
> 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 ..." ...
>
> The '==' operator adds trace filter with same efect as would
effect
> be added via set_ftrace_filter file.
>
> The '!=' operator adds trace filter with same efect as would
effect
> 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. Same syntax
> is supported/required as for the set_ftrace_filter and
> set_ftrace_notrace files.
>
> The '&&' operator is used for connecting multiple filter definitions
> together. It is possible to have more than one '==' and '!='
> opearators within one filter string.
operators
Interesting way to handle it. I'll have to test it out. I wonder if we
could also make this work the same way with ftrace too.
-- Steve
>
> Signed-off-by: Jiri Olsa <jolsa@...hat.com>
> ---
> kernel/trace/trace.h | 4 +-
> kernel/trace/trace_events_filter.c | 111 +++++++++++++++++++++++++++++++++---
> kernel/trace/trace_export.c | 5 ++
> 3 files changed, 110 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index c4330dc..fde4d2a 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -589,6 +589,8 @@ static inline int ftrace_trace_task(struct task_struct *task)
> static inline int ftrace_is_dead(void) { return 0; }
> #endif
>
> +int ftrace_event_is_function(struct ftrace_event_call *call);
> +
> /*
> * struct trace_parser - servers for reading the user input separated by spaces
> * @cont: set if the input is not complete - no final space char was found
> @@ -765,9 +767,7 @@ 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_events_filter.c b/kernel/trace/trace_events_filter.c
> index 7b0b04c..7434f50 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -54,6 +54,13 @@ struct filter_op {
> int precedence;
> };
>
> +static struct filter_op filter_ftrace_ops[] = {
> + { OP_AND, "&&", 1 },
> + { OP_NE, "!=", 2 },
> + { OP_EQ, "==", 2 },
> + { OP_NONE, "OP_NONE", 0 },
> +};
> +
> static struct filter_op filter_ops[] = {
> { OP_OR, "||", 1 },
> { OP_AND, "&&", 2 },
> @@ -81,6 +88,7 @@ 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 +104,7 @@ 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 {
> @@ -992,7 +1001,12 @@ 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
> @@ -1339,10 +1353,8 @@ 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;
> }
>
> @@ -1894,6 +1906,81 @@ 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;
> +};
> +
> +static int __ftrace_function_set_filter(int filter, char *buf, int len,
> + struct function_filter_data *data)
> +{
> + int *reset;
> +
> + reset = filter ? &data->first_filter : &data->first_notrace;
> +
> + if (filter)
> + ftrace_set_filter(data->ops, buf, len, *reset);
> + else
> + ftrace_set_notrace(data->ops, buf, len, *reset);
> +
> + if (*reset)
> + *reset = 0;
> +
> + return WALK_PRED_DEFAULT;
> +}
> +
> +static int ftrace_function_check_pred(struct filter_pred *pred)
> +{
> + struct ftrace_event_field *field = pred->field;
> +
> + /*
> + Check the predicate for function trace, verify:
> + - only '==' and '!=' is used
> + - the 'ip' field is used
> + */
> + if (WARN((pred->op != OP_EQ) && (pred->op != OP_NE),
> + "wrong operator for function filter: %d\n", pred->op))
> + return -EINVAL;
> +
> + if (strcmp(field->name, "ip"))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int ftrace_function_set_filter_cb(enum move_type move,
> + struct filter_pred *pred,
> + int *err, void *data)
> +{
> + if ((move != MOVE_DOWN) ||
> + (pred->left != FILTER_PRED_INVALID))
> + return WALK_PRED_DEFAULT;
> +
> + /* Double checking the predicate is valid for function trace. */
> + *err = ftrace_function_check_pred(pred);
> + if (*err)
> + return WALK_PRED_ABORT;
> +
> + return __ftrace_function_set_filter(pred->op == OP_EQ,
> + pred->regex.pattern,
> + pred->regex.len,
> + data);
> +}
> +
> +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);
> +}
> +
> int ftrace_profile_set_filter(struct perf_event *event, int event_id,
> char *filter_str)
> {
> @@ -1901,6 +1988,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
> struct event_filter *filter;
> struct filter_parse_state *ps;
> struct ftrace_event_call *call;
> + struct filter_op *fops = filter_ops;
>
> mutex_lock(&event_mutex);
>
> @@ -1925,14 +2013,21 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
> if (!ps)
> goto free_filter;
>
> - parse_init(ps, filter_ops, filter_str);
> + if (ftrace_event_is_function(call))
> + fops = filter_ftrace_ops;
> +
> + parse_init(ps, fops, filter_str);
> err = filter_parse(ps);
> if (err)
> goto free_ps;
>
> err = replace_preds(call, filter, ps, filter_str, false);
> - if (!err)
> - event->filter = filter;
> + if (!err) {
> + if (ftrace_event_is_function(call))
> + err = ftrace_function_set_filter(event, filter);
> + else
> + event->filter = filter;
> + }
>
> free_ps:
> filter_opstack_clear(ps);
> @@ -1940,7 +2035,7 @@ free_ps:
> kfree(ps);
>
> free_filter:
> - if (err)
> + if (err || ftrace_event_is_function(call))
> __free_filter(filter);
>
> out_unlock:
> diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> index 7b035ab..46c35e2 100644
> --- a/kernel/trace/trace_export.c
> +++ b/kernel/trace/trace_export.c
> @@ -208,4 +208,9 @@ struct ftrace_event_call __used event_##call = { \
> struct ftrace_event_call __used \
> __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
>
> +int ftrace_event_is_function(struct ftrace_event_call *call)
> +{
> + return call == &event_function;
> +}
> +
> #include "trace_entries.h"
--
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