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[PATCH 00/32] tracing: Inter-event (e.g. latency) support

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  [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 00:50 +0200
    [PATCH 17/32] tracing: Account for variables in named trigger compatibility Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 02/32] tracing: Reimplement log2 Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 10/32] tracing: Add NO_DISCARD event file flag Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 11/32] tracing: Add post-trigger flag to hist trigger command Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 19/32] tracing: Add variable reference handling to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 29/32] tracing: Add 'last error' error facility for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 04/32] ring-buffer: Redefine the unimplemented RINGBUF_TIME_TIME_STAMP Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
      Re: [PATCH 04/32] ring-buffer: Redefine the unimplemented RINGBUF_TIME_TIME_STAMP "Joel Fernandes (Google)" <joel.opensrc@gmail.com> - 2017-07-02 11:00 +0200
    [PATCH 06/32] tracing: Add ring buffer event param to hist field functions Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 16/32] tracing: Add variable support to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 20/32] tracing: Add support for dynamic tracepoints Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 24/32] tracing: Add 'onmax' hist trigger action support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 03/32] ring-buffer: Add interface for setting absolute time stamps Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 13/32] tracing: Add per-element variable support to tracing_map Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 09/32] tracing: Make traceprobe parsing code reusable Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 28/32] tracing: Add hist trigger support for variable reference aliases Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 32/32] tracing: Add a clock attribute for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 25/32] tracing: Allow whitespace to surround hist trigger filter Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 05/32] tracing: Give event triggers access to ring_buffer_event Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 21/32] tracing: Add hist trigger action hook Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 07/32] tracing: Increase tracing map KEYS_MAX size Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 30/32] tracing: Add inter-event hist trigger Documentation Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 31/32] tracing: Make tracing_set_clock() non-static Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 22/32] tracing: Add support for 'synthetic' events Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 12/32] tracing: Add hist trigger timestamp support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 18/32] tracing: Add simple expression support to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 08/32] tracing: Break out hist trigger assignment parsing Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 15/32] tracing: Add usecs modifier for hist trigger timestamps Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 23/32] tracing: Add 'onmatch' hist trigger action support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 14/32] tracing: Add hist_data member to hist_field Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 26/32] tracing: Make duplicate count from tracing_map available Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 01/32] tracing: Add hist_field_name() accessor Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    [PATCH 27/32] tracing: Add cpu field for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Steven Rostedt <rostedt@goodmis.org> - 2017-06-27 17:10 +0200
    Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Masami Hiramatsu <mhiramat@kernel.org> - 2017-06-28 16:30 +0200
      Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-28 21:20 +0200
    Re: [PATCH 00/32] tracing: Inter-event (e.g. latency) support "Joel Fernandes (Google)" <joel.opensrc@gmail.com> - 2017-07-01 09:10 +0200

Page 2 of 2 — ← Prev page 1 [2]

#1675168 — [PATCH 21/32] tracing: Add hist trigger action hook

Add a hook for executing extra actions whenever a histogram entry is
added or updated.

The default 'action' when a hist entry is added to a histogram is to
update the set of values associated with it.  Some applications may
want to perform additional actions at that point, such as generate
another event, or compare and save a maximum.

Add a simple framework for doing that; specific actions will be
implemented on top of it in later patches.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 114 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 111 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index d83d4ca..338a9d5 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -33,6 +33,7 @@ typedef u64 (*hist_field_fn_t) (struct hist_field *field,
 
 #define HIST_FIELD_OPERANDS_MAX	2
 #define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)
+#define HIST_ACTIONS_MAX	8
 
 enum field_op_id {
 	FIELD_OP_NONE,
@@ -233,6 +234,9 @@ struct hist_trigger_attrs {
 
 	char		*assignment_str[TRACING_MAP_VARS_MAX];
 	unsigned int	n_assignments;
+
+	char		*action_str[HIST_ACTIONS_MAX];
+	unsigned int	n_actions;
 };
 
 struct hist_trigger_data {
@@ -252,6 +256,21 @@ struct hist_trigger_data {
 	bool				remove;
 	struct hist_field               *var_refs[TRACING_MAP_VARS_MAX];
 	unsigned int			n_var_refs;
+
+	struct action_data		*actions[HIST_ACTIONS_MAX];
+	unsigned int			n_actions;
+};
+
+struct action_data;
+
+typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
+			     struct tracing_map_elt *elt, void *rec,
+			     struct ring_buffer_event *rbe,
+			     struct action_data *data, u64 *var_ref_vals);
+
+struct action_data {
+	action_fn_t		fn;
+	unsigned int		var_ref_idx;
 };
 
 static u64 hist_field_timestamp(struct hist_field *hist_field,
@@ -681,6 +700,9 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 	for (i = 0; i < attrs->n_assignments; i++)
 		kfree(attrs->assignment_str[i]);
 
+	for (i = 0; i < attrs->n_actions; i++)
+		kfree(attrs->action_str[i]);
+
 	kfree(attrs->name);
 	kfree(attrs->sort_key_str);
 	kfree(attrs->keys_str);
@@ -688,6 +710,16 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 	kfree(attrs);
 }
 
+static int parse_action(char *str, struct hist_trigger_attrs *attrs)
+{
+	int ret = 0;
+
+	if (attrs->n_actions >= HIST_ACTIONS_MAX)
+		return ret;
+
+	return ret;
+}
+
 static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
 {
 	int ret = 0;
@@ -755,8 +787,9 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 		else if (strcmp(str, "clear") == 0)
 			attrs->clear = true;
 		else {
-			ret = -EINVAL;
-			goto free;
+			ret = parse_action(str, attrs);
+			if (ret)
+				goto free;
 		}
 	}
 
@@ -1722,11 +1755,63 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 	return ret;
 }
 
+static void destroy_actions(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		kfree(data);
+	}
+}
+
+static int create_actions(struct hist_trigger_data *hist_data,
+			  struct trace_event_file *file)
+{
+	unsigned int i;
+	int ret = 0;
+	char *str;
+
+	for (i = 0; i < hist_data->attrs->n_actions; i++) {
+		str = hist_data->attrs->action_str[i];
+	}
+
+	return ret;
+}
+
+static void print_actions(struct seq_file *m,
+			  struct hist_trigger_data *hist_data,
+			  struct tracing_map_elt *elt)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+	}
+}
+
+static void print_actions_spec(struct seq_file *m,
+			       struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+	}
+}
+
 static void destroy_hist_data(struct hist_trigger_data *hist_data)
 {
+	if (!hist_data)
+		return;
+
 	destroy_hist_trigger_attrs(hist_data->attrs);
 	destroy_hist_fields(hist_data);
 	tracing_map_destroy(hist_data->map);
+
+	destroy_actions(hist_data);
+
 	kfree(hist_data);
 }
 
@@ -1886,6 +1971,20 @@ static inline void add_to_key(char *compound_key, void *key,
 	memcpy(compound_key + key_field->offset, key, size);
 }
 
+static void
+hist_trigger_actions(struct hist_trigger_data *hist_data,
+		     struct tracing_map_elt *elt, void *rec,
+		     struct ring_buffer_event *rbe, u64 *var_ref_vals)
+{
+	struct action_data *data;
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		data = hist_data->actions[i];
+		data->fn(hist_data, elt, rec, rbe, data, var_ref_vals);
+	}
+}
+
 static void event_hist_trigger(struct event_trigger_data *data, void *rec,
 			       struct ring_buffer_event *rbe)
 {
@@ -1941,6 +2040,9 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec,
 		return;
 
 	hist_trigger_elt_update(hist_data, elt, rec, rbe, var_ref_vals);
+
+	if (resolve_var_refs(hist_data, key, var_ref_vals, true))
+		hist_trigger_actions(hist_data, elt, rec, rbe, var_ref_vals);
 }
 
 static void hist_trigger_stacktrace_print(struct seq_file *m,
@@ -2278,6 +2380,8 @@ static int event_hist_trigger_print(struct seq_file *m,
 	}
 	seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits));
 
+	print_actions_spec(m, hist_data);
+
 	if (data->filter_str)
 		seq_printf(m, " if %s", data->filter_str);
 
@@ -2740,6 +2844,10 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 	if (has_hist_vars(hist_data))
 		save_hist_vars(hist_data);
 
+	ret = create_actions(hist_data, file);
+	if (ret)
+		goto out_unreg;
+
 	ret = tracing_map_init(hist_data->map);
 	if (ret)
 		goto out_unreg;
@@ -2761,8 +2869,8 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 	remove_hist_vars(hist_data);
 
 	kfree(trigger_data);
-
 	destroy_hist_data(hist_data);
+
 	goto out;
 }
 
-- 
1.9.3

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#1675170 — [PATCH 07/32] tracing: Increase tracing map KEYS_MAX size

The current default for the number of subkeys in a compound key is 2,
which is too restrictive.  Increase it to a more realistic value of 3.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/tracing_map.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h
index 618838f..f097511 100644
--- a/kernel/trace/tracing_map.h
+++ b/kernel/trace/tracing_map.h
@@ -5,7 +5,7 @@
 #define TRACING_MAP_BITS_MAX		17
 #define TRACING_MAP_BITS_MIN		7
 
-#define TRACING_MAP_KEYS_MAX		2
+#define TRACING_MAP_KEYS_MAX		3
 #define TRACING_MAP_VALS_MAX		3
 #define TRACING_MAP_FIELDS_MAX		(TRACING_MAP_KEYS_MAX + \
 					 TRACING_MAP_VALS_MAX)
-- 
1.9.3

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#1675171 — [PATCH 30/32] tracing: Add inter-event hist trigger Documentation

Add background and details on inter-event hist triggers, including
hist variables, synthetic events, and actions.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 Documentation/trace/events.txt | 376 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 376 insertions(+)

diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index f271d87..888907c 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -571,6 +571,7 @@ The following commands are supported:
 	.sym-offset display an address as a symbol and offset
 	.syscall    display a syscall id as a system call name
 	.execname   display a common_pid as a program name
+	.usecs      display a $common_timestamp in microseconds
 
   Note that in general the semantics of a given field aren't
   interpreted when applying a modifier to it, but there are some
@@ -2101,3 +2102,378 @@ The following commands are supported:
         Hits: 489
         Entries: 7
         Dropped: 0
+
+6.3 Inter-event hist triggers
+-----------------------------
+
+Inter-event hist triggers are hist triggers that combine values from
+one or more other events and create a histogram using that data.  Data
+from an inter-event histogram can in turn become the source for
+further combined histograms, thus providing a chain of related
+histograms, which is important for some applications.
+
+The most important example of an inter-event quantity that can be used
+in this manner is latency, which is simply a difference in timestamps
+between two events (although trace events don't have an externally
+visible timestamp field, the inter-event hist trigger support adds a
+pseudo-field to all events named '$common_timestamp' which can be used
+as if it were an actual event field).  Although latency is the most
+important inter-event quantity, note that because the support is
+completely general across the trace event subsystem, any event field
+can be used in an inter-event quantity.
+
+An example of a histogram that combines data from other histograms
+into a useful chain would be a 'wakeupswitch latency' histogram that
+combines a 'wakeup latency' histogram and a 'switch latency'
+histogram.
+
+Normally, a hist trigger specification consists of a (possibly
+compound) key along with one or more numeric values, which are
+continually updated sums associated with that key.  A histogram
+specification in this case consists of individual key and value
+specifications that refer to trace event fields associated with a
+single event type.
+
+The inter-event hist trigger extension allows fields from multiple
+events to be referenced and combined into a multi-event histogram
+specification.  In support of this overall goal, a few enabling
+features have been added to the hist trigger support:
+
+  - In order to compute an inter-event quantity, a value from one
+    event needs to saved and then referenced from another event.  This
+    requires the introduction of support for histogram 'variables'.
+
+  - The computation of inter-event quantities and their combination
+    require some minimal amount of support for applying simple
+    expressions to variables (+ and -).
+
+  - A histogram consisting of inter-event quantities isn't logically a
+    histogram on either event (so having the 'hist' file for either
+    event host the histogram output doesn't really make sense).  To
+    address the idea that the histogram is associated with a
+    combination of events, support is added allowing the creation of
+    'synthetic' events that are events derived from other events.
+    These synthetic events are full-fledged events just like any other
+    and can be used as such, as for instance to create the
+    'combination' histograms mentioned previously.
+
+  - A set of 'actions' can be associated with histogram entries -
+    these can be used to generate the previously mentioned synthetic
+    events, but can also be used for other purposes, such as for
+    example saving context when a 'max' latency has been hit.
+
+  - Trace events don't have a 'timestamp' associated with them, but
+    there is an implicit timestamp saved along with an event in the
+    underlying ftrace ring buffer.  This timestamp is now exposed as a
+    a synthetic field named '$common_timestamp' which can be used in
+    histograms as if it were any other event field.  Note that it has
+    a '$' prefixed to it - this is meant to indicate that it isn't an
+    actual field in the trace format but rather is a synthesized value
+    that nonetheless can be used as if it were an actual field.  By
+    default it is in units of nanoseconds; appending '.usecs' to a
+    common_timestamp field changes the units to microseconds.
+
+These features are decribed in more detail in the following sections.
+
+6.3.1 Histogram Variables
+-------------------------
+
+Variables are simply named locations used for saving and retrieving
+values between matching events.  A 'matching' event is defined as an
+event that has a matching key - if a variable is saved for a histogram
+entry corresponding to that key, any subsequent event with a matching
+key can access that variable.
+
+A variable's value is normally available to any subsequent event until
+it is set to something else by a subsequent event.  The one exception
+to that rule is that any variable used in an expression is essentially
+'read-once' - once it's used by an expression in a subsequent event,
+it's reset to its 'unset' state, which means it can't be used again
+unless it's set again.  This ensures not only that an event doesn't
+use an uninitialized variable in a calculation, but that that variable
+is used only once and not for any unrelated subsequent match.
+
+The basic syntax for saving a variable is to simply prefix a unique
+variable name not corresponding to any keyword along with an '=' sign
+to any event field.
+
+Either keys or values can be saved and retrieved in this way.  This
+creates a variable named 'ts0' for a histogram entry with the key
+'next_pid':
+
+  # echo 'hist:keys=next_pid:vals=ts0=$common_timestamp ... >> event/trigger
+
+The ts0 variable can be accessed by any subsequent event having the
+same pid as 'next_pid'.
+
+Variable references are formed by prepending the variable name with
+the '$' sign.  Thus for example, the ts0 variable above would be
+referenced as '$ts0' in subsequent expressions.
+
+Because 'vals=' is used, the $common_timestamp variable value above
+will also be summed as a normal histogram value would (though for a
+timestamp it makes little sense).
+
+The below shows that a key value can also be saved in the same way:
+
+  # echo 'hist:key=timer_pid=common_pid ...' >> event/trigger
+
+If a variable isn't a key variable or prefixed with 'vals=', the
+associated event field will be saved in a variable but won't be summed
+as a value:
+
+  # echo 'hist:keys=next_pid:ts1=$common_timestamp ... >> event/trigger
+
+Multiple variables can be assigned at the same time.  The below would
+result in both ts0 and b being created as variables, with both
+common_timestamp and field1 additionally being summed as values:
+
+  # echo 'hist:keys=pid:vals=ts0=$common_timestamp,b=field1 ... >> event/trigger
+
+Any number of variables not bound to a 'vals=' prefix can also be
+assigned by simply separating them with colons.  Below is the same
+thing but without the values being summed in the histogram:
+
+  # echo 'hist:keys=pid:ts0=$common_timestamp:b=field1 ... >> event/trigger
+
+Variables set as above can be referenced and used in expressions on
+another event.
+
+For example, here's how a latency can be calculated:
+
+  # echo 'hist:keys=pid,prio:ts0=$common_timestamp ... >> event1/trigger
+  # echo 'hist:keys=next_pid:wakeup_lat=$common_timestamp-$ts0 ... >> event2/trigger
+
+In the first line above, the event's timetamp is saved into the
+variable ts0.  In the next line, ts0 is subtracted from the second
+event's timestamp to produce the latency, which is then assigned into
+yet another variable, 'wakeup_lat'.  The hist trigger below in turn
+makes use of the wakeup_lat variable to compute a combined latency
+using the same key and variable from yet another event:
+
+  # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ... >> event3/trigger
+
+6.3.2 Synthetic Events
+----------------------
+
+Synthetic events are user-defined events generated from hist trigger
+variables or fields associated with one or more other events.  Their
+purpose is to provide a mechanism for displaying data spanning
+multiple events consistent with the existing and already familiar
+usage for normal events.
+
+To define a synthetic event, the user writes a simple specification
+consisting of the name of the new event along with one or more
+variables and their types, which can be any valid field type,
+separated by semicolons, to the tracing/synthetic_events file.
+
+For instance, the following creates a new event named 'wakeup_latency'
+with 3 fields: lat, pid, and prio.  Each of those fields is simply a
+variable reference to a variable on another event:
+
+  # echo 'wakeup_latency \
+          u64 lat; \
+          pid_t pid; \
+	  int prio' >> \
+	  /sys/kernel/debug/tracing/synthetic_events
+
+Reading the tracing/synthetic_events file lists all the currently
+defined synthetic events, in this case the event defined above:
+
+  # cat /sys/kernel/debug/tracing/synthetic_events
+    wakeup_latency u64 lat; pid_t pid; int prio
+
+An existing synthetic event definition can be removed by prepending
+the command that defined it with a '!':
+
+  # echo '!wakeup_latency u64 lat pid_t pid int prio' >> \
+    /sys/kernel/debug/tracing/synthetic_events
+
+At this point, there isn't yet an actual 'wakeup_latency' event
+instantiated in the event subsytem - for this to happen, a 'hist
+trigger action' needs to be instantiated and bound to actual fields
+and variables defined on other events (see Section 6.3.3 below).
+
+Once that is done, an event instance is created, and a histogram can
+be defined using it:
+
+  # echo 'hist:keys=pid,prio,lat.log2:sort=pid,lat' >> \
+        /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
+
+The new event is created under the tracing/events/synthetic/ directory
+and looks and behaves just like any other event:
+
+  # ls /sys/kernel/debug/tracing/events/synthetic/wakeup_latency
+        enable  filter  format  hist  id  trigger
+
+Like any other event, once a histogram is enabled for the event, the
+output can be displayed by reading the event's 'hist' file.
+
+6.3.3 Hist trigger 'actions'
+----------------------------
+
+A hist trigger 'action' is a function that's executed whenever a
+histogram entry is added or updated.
+
+The default 'action' if no special function is explicity specified is
+as it always has been, to simply update the set of values associated
+with an entry.  Some applications, however, may want to perform
+additional actions at that point, such as generate another event, or
+compare and save a maximum.
+
+The following additional actions are available.  To specify an action
+for a given event, simply specify the action between colons in the
+hist trigger specification.
+
+  - onmatch(matching.event).<synthetic_event_name>(param list)
+
+    The 'onmatch(matching.event).<synthetic_event_name>(params)' hist
+    trigger action is invoked whenever an event matches and the
+    histogram entry would be added or updated.  It causes the named
+    synthetic event to be generated with the values given in the
+    'param list'.  The result is the generation of a synthetic event
+    that consists of the values contained in those variables at the
+    time the invoking event was hit.
+
+    The 'param list' consists of one or more parameters which may be
+    either variables or fields defined on either the 'matching.event'
+    or the target event.  The variables or fields specified in the
+    param list may be either fully-qualified or unqualified.  If a
+    variable is specified as unqualified, it must be unique between
+    the two events.  A field name used as a param can be unqualified
+    if it refers to the target event, but must be fully qualified if
+    it refers to the matching event.  A fully-qualified name is of the
+    form 'system.event_name.$var_name' or 'system.event_name.field'.
+
+    The 'matching.event' specification is simply the fully qualified
+    event name of the event that matches the target event for the
+    onmatch() functionality, in the form 'system.event_name'.
+
+    Finally, the number and type of variables/fields in the 'param
+    list' must match the number and types of the fields in the
+    synthetic event being generated.
+
+    As an example the below defines a simple synthetic event and uses
+    a variable defined on the sched_wakeup_new event as a parameter
+    when invoking the synthetic event.  Here we define the synthetic
+    event:
+
+    # echo 'wakeup_new_test pid_t pid' >> \
+           /sys/kernel/debug/tracing/synthetic_events
+
+    # cat /sys/kernel/debug/tracing/synthetic_events
+          wakeup_new_test pid_t pid
+
+    The following hist trigger both defines the missing testpid
+    variable and specifies an onmatch() action that generates a
+    wakeup_new_test synthetic event whenever a sched_wakeup_new event
+    occurs, which because of the 'if comm == "cyclictest"' filter only
+    happens when the executable is cyclictest:
+
+    # echo 'hist:keys=testpid=pid:onmatch(sched.sched_wakeup_new).\
+            wakeup_new_test($testpid) if comm=="cyclictest"' >> \
+            /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger
+
+    Creating and displaying a histogram based on those events is now
+    just a matter of using the fields and new synthetic event in the
+    tracing/events/synthetic directory, as usual:
+
+    # echo 'hist:keys=pid:sort=pid' >> \
+           /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger
+
+    Running 'cyclictest' should cause wakeup_new events to generate
+    wakeup_new_test synthetic events which should result in histogram
+    output in the wakeup_new_test event's hist file:
+
+    # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/hist
+
+    A more typical usage would be to use two events to calculate a
+    latency.  The following example uses a set of hist triggers to
+    produce a 'wakeup_latency' histogram:
+
+    First, we define a 'wakeup_latency' synthetic event:
+
+    # echo 'wakeup_latency u64 lat; pid_t pid; int prio' >> \
+            /sys/kernel/debug/tracing/synthetic_events
+
+    Next, we specify that whenever we see a sched_wakeup event for a
+    cyclictest thread, save the timestamp in a 'ts0' variable:
+
+    # echo 'hist:keys=saved_pid=pid:ts0=$common_timestamp.usecs \
+            if comm=="cyclictest"' >> \
+	    /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
+
+    Then, when the corresponding thread is actually scheduled onto the
+    CPU by a sched_switch event, calculate the latency and use that
+    along with another variable and an event field to generate a
+    wakeup_latency synthetic event:
+
+    # echo 'hist:keys=next_pid:wakeup_lat=$common_timestamp.usecs-$ts0:\
+            onmatch(sched.sched_wakeup).wakeup_latency($wakeup_lat,\
+	            $saved_pid,next_prio) if next_comm=="cyclictest"' >> \
+	    /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
+
+    We also need to create a histogram on the wakeup_latency synthetic
+    event in order to aggregate the generated synthetic event data:
+
+    # echo 'hist:keys=pid,prio,lat:sort=pid,lat' >> \
+            /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
+
+    Finally, once we've run cyclictest to actually generate some
+    events, we can see the output by looking at the wakeup_latency
+    synthetic event's hist file:
+
+    # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/hist
+
+  - onmax(var).save(field,...)
+
+    The 'onmax(var).save(field,...)' hist trigger action is invoked
+    whenever the value of 'var' associated with a histogram entry
+    exceeds the current maximum contained in that variable.
+
+    The end result is that the trace event fields specified as the
+    onmax.save() params will be saved if 'var' exceeds the current
+    maximum for that hist trigger entry.  This allows context from the
+    event that exhibited the new maximum to be saved for later
+    reference.  When the histogram is displayed, additional fields
+    displaying the saved values will be printed.
+
+    As an example the below defines a couple of hist triggers, one for
+    sched_wakeup and another for sched_switch, keyed on pid.  Whenever
+    a sched_wakeup occurs, the timestamp is saved in the entry
+    corresponding to the current pid, and when the scheduler switches
+    back to that pid, the timestamp difference is calculated.  If the
+    resulting latency, stored in wakeup_lat, exceeds the current
+    maximum latency, the values specified in the save() fields are
+    recoreded:
+
+    # echo 'hist:keys=pid:ts0=$common_timestamp.usecs \
+            if comm=="cyclictest"' >> \
+            /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
+
+    # echo 'hist:keys=next_pid:\
+            wakeup_lat=$common_timestamp.usecs-$ts0:\
+            onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm) \
+            if next_comm=="cyclictest"' >> \
+            /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
+
+    When the histogram is displayed, the max value and the saved
+    values corresponding to the max are displayed following the rest
+    of the fields:
+
+    # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
+      { next_pid:       2255 } hitcount:        239
+        common_timestamp-ts0:          0
+        max:         27
+	next_comm: cyclictest
+        prev_pid:          0  prev_prio:        120  prev_comm: swapper/1
+
+      { next_pid:       2256 } hitcount:       2355
+        common_timestamp-ts0: 0
+        max:         49  next_comm: cyclictest
+        prev_pid:          0  prev_prio:        120  prev_comm: swapper/0
+
+      Totals:
+          Hits: 12970
+          Entries: 2
+          Dropped: 0
-- 
1.9.3

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#1675172 — [PATCH 31/32] tracing: Make tracing_set_clock() non-static

Allow tracing code outside of trace.c to access tracing_set_clock().

Some applications may require a particular clock in order to function
properly, such as latency calculations.

Also, add an accessor returning the current clock string.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace.c | 2 +-
 kernel/trace/trace.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ec84822..5e86fb0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6007,7 +6007,7 @@ static int tracing_clock_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int tracing_set_clock(struct trace_array *tr, const char *clockstr)
+int tracing_set_clock(struct trace_array *tr, const char *clockstr)
 {
 	int i;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7dc13fa..6ee9952 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -282,6 +282,7 @@ enum {
 extern void trace_array_put(struct trace_array *tr);
 
 extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
+extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);
 
 extern bool trace_clock_in_ns(struct trace_array *tr);
 
-- 
1.9.3

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#1675173 — [PATCH 22/32] tracing: Add support for 'synthetic' events

Synthetic events are user-defined events generated from hist trigger
variables saved from one or more other events.

To define a synthetic event, the user writes a simple specification
consisting of the name of the new event along with one or more
variables and their type(s), to the tracing/synthetic_events file.

For instance, the following creates a new event named 'wakeup_latency'
with 3 fields: lat, pid, and prio:

    # echo 'wakeup_latency u64 lat; pid_t pid; int prio' >> \
      /sys/kernel/debug/tracing/synthetic_events

Reading the tracing/synthetic_events file lists all the
currently-defined synthetic events, in this case the event we defined
above:

    # cat /sys/kernel/debug/tracing/synthetic_events
    wakeup_latency u64 lat; pid_t pid; int prio

At this point, the synthetic event is ready to use, and a histogram
can be defined using it:

    # echo 'hist:keys=pid,prio,lat.log2:sort=pid,lat' >> \
    /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger

The new event is created under the tracing/events/synthetic/ directory
and looks and behaves just like any other event:

    # ls /sys/kernel/debug/tracing/events/synthetic/wakeup_latency
      enable  filter  format  hist  id  trigger

Although a histogram can be defined for it, nothing will happen until
an action tracing that event via the trace_synth() function occurs.
The trace_synth() function is very similar to all the other trace_*
invocations spread throughout the kernel, except in this case the
trace_ function and its corresponding tracepoint isn't statically
generated but defined by the user at run-time.

How this can be automatically hooked up via a hist trigger 'action' is
discussed in a subsequent patch.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 738 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 738 insertions(+)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 338a9d5..e11b3a3 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -20,10 +20,14 @@
 #include <linux/slab.h>
 #include <linux/stacktrace.h>
 #include <linux/rculist.h>
+#include <linux/tracefs.h>
 
 #include "tracing_map.h"
 #include "trace.h"
 
+#define SYNTH_SYSTEM		"synthetic"
+#define SYNTH_FIELDS_MAX	16
+
 struct hist_field;
 
 typedef u64 (*hist_field_fn_t) (struct hist_field *field,
@@ -261,6 +265,23 @@ struct hist_trigger_data {
 	unsigned int			n_actions;
 };
 
+struct synth_field {
+	char *type;
+	char *name;
+	unsigned int size;
+	bool is_signed;
+};
+
+struct synth_event {
+	struct list_head			list;
+	char					*name;
+	struct synth_field			**fields;
+	unsigned int				n_fields;
+	struct trace_event_class		class;
+	struct trace_event_call			call;
+	struct tracepoint			*tp;
+};
+
 struct action_data;
 
 typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
@@ -273,6 +294,688 @@ struct action_data {
 	unsigned int		var_ref_idx;
 };
 
+static LIST_HEAD(synth_event_list);
+static DEFINE_MUTEX(synth_event_mutex);
+
+struct synth_trace_event {
+	struct trace_entry	ent;
+	int			n_fields;
+	u64			fields[];
+};
+
+static int synth_event_define_fields(struct trace_event_call *call)
+{
+	struct synth_trace_event trace;
+	int offset = offsetof(typeof(trace), fields);
+	struct synth_event *event = call->data;
+	unsigned int i, size;
+	char *name, *type;
+	bool is_signed;
+	int ret = 0;
+
+	for (i = 0; i < event->n_fields; i++) {
+		size = event->fields[i]->size;
+		is_signed = event->fields[i]->is_signed;
+		type = event->fields[i]->type;
+		name = event->fields[i]->name;
+		ret = trace_define_field(call, type, name, offset, size,
+					 is_signed, FILTER_OTHER);
+		offset += sizeof(u64);
+	}
+
+	return ret;
+}
+
+static enum print_line_t print_synth_event(struct trace_iterator *iter,
+					   int flags,
+					   struct trace_event *event)
+{
+	struct trace_array *tr = iter->tr;
+	struct trace_seq *s = &iter->seq;
+	struct synth_trace_event *entry;
+	struct synth_event *se;
+	unsigned int i;
+
+	entry = (struct synth_trace_event *)iter->ent;
+	se = container_of(event, struct synth_event, call.event);
+
+	trace_seq_printf(s, "%s: ", se->name);
+
+	for (i = 0; i < entry->n_fields; i++) {
+		if (trace_seq_has_overflowed(s))
+			goto end;
+
+		/* parameter types */
+		if (tr->trace_flags & TRACE_ITER_VERBOSE)
+			trace_seq_printf(s, "%s ", "u64");
+
+		/* parameter values */
+		trace_seq_printf(s, "%s=%llu%s", se->fields[i]->name,
+				 entry->fields[i],
+				 i == entry->n_fields - 1 ? "" : ", ");
+	}
+end:
+	trace_seq_putc(s, '\n');
+
+	return trace_handle_return(s);
+}
+
+static struct trace_event_functions synth_event_funcs = {
+	.trace		= print_synth_event
+};
+
+static notrace void trace_event_raw_event_synth(void *__data,
+						u64 *var_ref_vals,
+						unsigned int var_ref_idx)
+{
+	struct trace_event_file *trace_file = __data;
+	struct synth_trace_event *entry;
+	struct trace_event_buffer fbuffer;
+	int fields_size;
+	unsigned int i;
+
+	struct synth_event *event;
+
+	event = trace_file->event_call->data;
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	fields_size = event->n_fields * sizeof(u64);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + fields_size);
+	if (!entry)
+		return;
+
+	entry->n_fields = event->n_fields;
+
+	for (i = 0; i < event->n_fields; i++)
+		entry->fields[i] = var_ref_vals[var_ref_idx + i];
+
+	trace_event_buffer_commit(&fbuffer);
+}
+
+static void free_synth_event_print_fmt(struct trace_event_call *call)
+{
+	if (call)
+		kfree(call->print_fmt);
+}
+
+static int __set_synth_event_print_fmt(struct synth_event *event,
+				       char *buf, int len)
+{
+	int pos = 0;
+	int i;
+
+	/* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
+	for (i = 0; i < event->n_fields; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
+				event->fields[i]->name, sizeof(u64),
+				i == event->n_fields - 1 ? "" : ", ");
+	}
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
+
+	for (i = 0; i < event->n_fields; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO,
+				", ((u64)(REC->%s))", event->fields[i]->name);
+	}
+
+#undef LEN_OR_ZERO
+
+	/* return the length of print_fmt */
+	return pos;
+}
+
+static int set_synth_event_print_fmt(struct trace_event_call *call)
+{
+	struct synth_event *event = call->data;
+	char *print_fmt;
+	int len;
+
+	/* First: called with 0 length to calculate the needed length */
+	len = __set_synth_event_print_fmt(event, NULL, 0);
+
+	print_fmt = kmalloc(len + 1, GFP_KERNEL);
+	if (!print_fmt)
+		return -ENOMEM;
+
+	/* Second: actually write the @print_fmt */
+	__set_synth_event_print_fmt(event, print_fmt, len + 1);
+	call->print_fmt = print_fmt;
+
+	return 0;
+}
+
+int dynamic_trace_event_reg(struct trace_event_call *call,
+			    enum trace_reg type, void *data)
+{
+	struct trace_event_file *file = data;
+
+	WARN_ON(!(call->flags & TRACE_EVENT_FL_TRACEPOINT));
+	switch (type) {
+	case TRACE_REG_REGISTER:
+		return dynamic_tracepoint_probe_register(call->tp,
+							 call->class->probe,
+							 file);
+	case TRACE_REG_UNREGISTER:
+		tracepoint_probe_unregister(call->tp,
+					    call->class->probe,
+					    file, true);
+		return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return dynamic_tracepoint_probe_register(call->tp,
+							 call->class->perf_probe,
+							 call);
+	case TRACE_REG_PERF_UNREGISTER:
+		tracepoint_probe_unregister(call->tp,
+					    call->class->perf_probe,
+					    call, true);
+		return 0;
+	case TRACE_REG_PERF_OPEN:
+	case TRACE_REG_PERF_CLOSE:
+	case TRACE_REG_PERF_ADD:
+	case TRACE_REG_PERF_DEL:
+		return 0;
+#endif
+	}
+	return 0;
+}
+
+static void free_synth_field(struct synth_field *field)
+{
+	kfree(field->type);
+	kfree(field->name);
+	kfree(field);
+}
+
+static bool synth_field_signed(char *type)
+{
+	if (strncmp(type, "u", 1) == 0)
+		return false;
+
+	return true;
+}
+
+static unsigned int synth_field_size(char *type)
+{
+	unsigned int size = 0;
+
+	if (strcmp(type, "s64") == 0)
+		size = sizeof(s64);
+	else if (strcmp(type, "u64") == 0)
+		size = sizeof(u64);
+	else if (strcmp(type, "s32") == 0)
+		size = sizeof(s32);
+	else if (strcmp(type, "u32") == 0)
+		size = sizeof(u32);
+	else if (strcmp(type, "s16") == 0)
+		size = sizeof(s16);
+	else if (strcmp(type, "u16") == 0)
+		size = sizeof(u16);
+	else if (strcmp(type, "s8") == 0)
+		size = sizeof(s8);
+	else if (strcmp(type, "u8") == 0)
+		size = sizeof(u8);
+	else if (strcmp(type, "char") == 0)
+		size = sizeof(char);
+	else if (strcmp(type, "unsigned char") == 0)
+		size = sizeof(unsigned char);
+	else if (strcmp(type, "int") == 0)
+		size = sizeof(int);
+	else if (strcmp(type, "unsigned int") == 0)
+		size = sizeof(unsigned int);
+	else if (strcmp(type, "long") == 0)
+		size = sizeof(long);
+	else if (strcmp(type, "unsigned long") == 0)
+		size = sizeof(unsigned long);
+	else if (strcmp(type, "pid_t") == 0)
+		size = sizeof(pid_t);
+	else if (strstr(type, "[") == 0)
+		size = sizeof(u64);
+
+	return size;
+}
+
+static struct synth_field *parse_synth_field(char *field_type,
+					     char *field_name)
+{
+	struct synth_field *field;
+	int len, ret = 0;
+	char *array;
+
+	if (field_type[0] == ';')
+		field_type++;
+
+	len = strlen(field_name);
+	if (field_name[len - 1] == ';')
+		field_name[len - 1] = '\0';
+
+	field = kzalloc(sizeof(*field), GFP_KERNEL);
+	if (!field)
+		return ERR_PTR(-ENOMEM);
+
+	len = strlen(field_type) + 1;
+	array = strchr(field_name, '[');
+	if (array)
+		len += strlen(array);
+	field->type = kzalloc(len, GFP_KERNEL);
+	if (!field->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
+	strcat(field->type, field_type);
+	if (array)
+		strcat(field->type, array);
+
+	field->size = synth_field_size(field->type);
+	if (!field->size) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	field->is_signed = synth_field_signed(field->type);
+
+	field->name = kstrdup(field_name, GFP_KERNEL);
+	if (!field->name) {
+		ret = -ENOMEM;
+		goto free;
+	}
+ out:
+	return field;
+ free:
+	free_synth_field(field);
+	field = ERR_PTR(ret);
+	goto out;
+}
+
+static void free_synth_tracepoint(struct tracepoint *tp)
+{
+	if (!tp)
+		return;
+
+	kfree(tp->name);
+	kfree(tp);
+}
+
+static struct tracepoint *alloc_synth_tracepoint(char *name)
+{
+	struct tracepoint *tp;
+	int ret = 0;
+
+	tp = kzalloc(sizeof(*tp), GFP_KERNEL);
+	if (!tp) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	tp->name = kstrdup(name, GFP_KERNEL);
+	if (!tp->name) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	return tp;
+ free:
+	free_synth_tracepoint(tp);
+
+	return ERR_PTR(ret);
+}
+
+static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
+			       unsigned int var_ref_idx)
+{
+	struct tracepoint *tp = event->tp;
+
+	if (unlikely(atomic_read(&tp->key.enabled) > 0)) {
+		struct tracepoint_func *it_func_ptr;
+		void *it_func;
+		void *__data;
+
+		if (!(cpu_online(raw_smp_processor_id())))
+			return;
+
+		it_func_ptr = rcu_dereference_sched((tp)->funcs);
+		if (it_func_ptr) {
+			do {
+				it_func = (it_func_ptr)->func;
+				__data = (it_func_ptr)->data;
+				((void(*)(void *__data, u64 *var_ref_vals, unsigned int var_ref_idx))(it_func))(__data, var_ref_vals, var_ref_idx);
+			} while ((++it_func_ptr)->func);
+		}
+	}
+}
+
+static struct synth_event *find_synth_event(const char *name)
+{
+	struct synth_event *event;
+
+	list_for_each_entry(event, &synth_event_list, list) {
+		if (strcmp(event->name, name) == 0)
+			return event;
+	}
+
+	return NULL;
+}
+
+static int register_synth_event(struct synth_event *event)
+{
+	struct trace_event_call *call = &event->call;
+	int ret = 0;
+
+	event->call.class = &event->class;
+	event->class.system = kstrdup(SYNTH_SYSTEM, GFP_KERNEL);
+	if (!event->class.system) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	event->tp = alloc_synth_tracepoint(event->name);
+	if (IS_ERR(event->tp)) {
+		ret = PTR_ERR(event->tp);
+		event->tp = NULL;
+		goto out;
+	}
+
+	INIT_LIST_HEAD(&call->class->fields);
+	call->event.funcs = &synth_event_funcs;
+	call->class->define_fields = synth_event_define_fields;
+
+	ret = register_trace_event(&call->event);
+	if (!ret) {
+		ret = -ENODEV;
+		goto out;
+	}
+	call->flags = TRACE_EVENT_FL_TRACEPOINT;
+	call->class->reg = dynamic_trace_event_reg;
+	call->class->probe = trace_event_raw_event_synth;
+	call->data = event;
+	call->tp = event->tp;
+	ret = trace_add_event_call(call);
+	if (ret) {
+		pr_warn("Failed to register synthetic event: %s\n",
+			trace_event_name(call));
+		goto err;
+	}
+
+	ret = set_synth_event_print_fmt(call);
+	if (ret < 0) {
+		trace_remove_event_call(call);
+		goto err;
+	}
+ out:
+	return ret;
+ err:
+	unregister_trace_event(&call->event);
+	goto out;
+}
+
+static int unregister_synth_event(struct synth_event *event)
+{
+	struct trace_event_call *call = &event->call;
+	int ret;
+
+	ret = trace_remove_event_call(call);
+	if (ret) {
+		pr_warn("Failed to remove synthetic event: %s\n",
+			trace_event_name(call));
+		free_synth_event_print_fmt(call);
+		unregister_trace_event(&call->event);
+	}
+
+	return ret;
+}
+
+static void remove_synth_event(struct synth_event *event)
+{
+	unregister_synth_event(event);
+	list_del(&event->list);
+}
+
+static int add_synth_event(struct synth_event *event)
+{
+	int ret;
+
+	ret = register_synth_event(event);
+	if (ret)
+		return ret;
+
+	list_add(&event->list, &synth_event_list);
+
+	return 0;
+}
+
+static void free_synth_event(struct synth_event *event)
+{
+	unsigned int i;
+
+	if (!event)
+		return;
+
+	for (i = 0; i < event->n_fields; i++)
+		free_synth_field(event->fields[i]);
+
+	kfree(event->fields);
+	kfree(event->name);
+	kfree(event->class.system);
+	free_synth_tracepoint(event->tp);
+	free_synth_event_print_fmt(&event->call);
+	kfree(event);
+}
+
+static struct synth_event *alloc_synth_event(char *event_name, int n_fields,
+					     struct synth_field **fields)
+{
+	struct synth_event *event;
+	unsigned int i;
+
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
+	if (!event) {
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	event->name = kstrdup(event_name, GFP_KERNEL);
+	if (!event->name) {
+		kfree(event);
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	event->fields = kcalloc(n_fields, sizeof(event->fields), GFP_KERNEL);
+	if (!event->fields) {
+		free_synth_event(event);
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	for (i = 0; i < n_fields; i++)
+		event->fields[i] = fields[i];
+
+	event->n_fields = n_fields;
+ out:
+	return event;
+}
+
+static int create_synth_event(int argc, char **argv)
+{
+	struct synth_field *fields[SYNTH_FIELDS_MAX];
+	struct synth_event *event = NULL;
+	bool delete_event = false;
+	int i, n_fields = 0, ret = 0;
+	char *name;
+
+	mutex_lock(&synth_event_mutex);
+
+	/*
+	 * Argument syntax:
+	 *  - Add synthetic event: <event_name> field[;field] ...
+	 *  - Remove synthetic event: !<event_name> field[;field] ...
+	 *      where 'field' = type field_name
+	 */
+	if (argc < 1) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	name = argv[0];
+	if (name[0] == '!') {
+		delete_event = true;
+		name++;
+	}
+
+	event = find_synth_event(name);
+	if (event) {
+		if (delete_event) {
+			remove_synth_event(event);
+			goto err;
+		} else
+			ret = -EEXIST;
+		goto out;
+	} else if (delete_event) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (argc < 2) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	for (i = 1; i < argc - 1; i++) {
+		if (strcmp(argv[i], ";") == 0)
+			continue;
+		if (n_fields == SYNTH_FIELDS_MAX) {
+			ret = -EINVAL;
+			goto out;
+		}
+		fields[n_fields] = parse_synth_field(argv[i], argv[i + 1]);
+		if (!fields[n_fields])
+			goto err;
+		i++; n_fields++;
+	}
+	if (i < argc) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	event = alloc_synth_event(name, n_fields, fields);
+	if (IS_ERR(event)) {
+		ret = PTR_ERR(event);
+		event = NULL;
+		goto err;
+	}
+
+	add_synth_event(event);
+ out:
+	mutex_unlock(&synth_event_mutex);
+
+	return ret;
+ err:
+	for (i = 0; i < n_fields; i++)
+		free_synth_field(fields[i]);
+	free_synth_event(event);
+
+	goto out;
+}
+
+static int release_all_synth_events(void)
+{
+	struct synth_event *event, *e;
+	int ret = 0;
+
+	mutex_lock(&synth_event_mutex);
+
+	list_for_each_entry_safe(event, e, &synth_event_list, list) {
+		remove_synth_event(event);
+		free_synth_event(event);
+	}
+
+	mutex_unlock(&synth_event_mutex);
+
+	return ret;
+}
+
+
+static void *synth_events_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&synth_event_mutex);
+
+	return seq_list_start(&synth_event_list, *pos);
+}
+
+static void *synth_events_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &synth_event_list, pos);
+}
+
+static void synth_events_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&synth_event_mutex);
+}
+
+static int synth_events_seq_show(struct seq_file *m, void *v)
+{
+	struct synth_field *field;
+	struct synth_event *event = v;
+	unsigned int i;
+
+	seq_printf(m, "%s\t", event->name);
+
+	for (i = 0; i < event->n_fields; i++) {
+		field = event->fields[i];
+
+		/* parameter values */
+		seq_printf(m, "%s %s%s", field->type, field->name,
+			   i == event->n_fields - 1 ? "" : "; ");
+	}
+
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+static const struct seq_operations synth_events_seq_op = {
+	.start  = synth_events_seq_start,
+	.next   = synth_events_seq_next,
+	.stop   = synth_events_seq_stop,
+	.show   = synth_events_seq_show
+};
+
+static int synth_events_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+		ret = release_all_synth_events();
+		if (ret < 0)
+			return ret;
+	}
+
+	return seq_open(file, &synth_events_seq_op);
+}
+
+static ssize_t synth_events_write(struct file *file,
+				  const char __user *buffer,
+				  size_t count, loff_t *ppos)
+{
+	return trace_parse_run_command(file, buffer, count, ppos,
+				       create_synth_event);
+}
+
+static const struct file_operations synth_events_fops = {
+	.open           = synth_events_open,
+	.write		= synth_events_write,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
 static u64 hist_field_timestamp(struct hist_field *hist_field,
 				struct tracing_map_elt *elt,
 				struct ring_buffer_event *rbe,
@@ -3028,3 +3731,38 @@ __init int register_trigger_hist_enable_disable_cmds(void)
 
 	return ret;
 }
+
+static __init int trace_events_hist_init(void)
+{
+	struct dentry *entry = NULL;
+	struct trace_array *tr;
+	struct dentry *d_tracer;
+	int err = 0;
+
+	tr = top_trace_array();
+	if (!tr) {
+		err = -ENODEV;
+		goto err;
+	}
+
+	d_tracer = tracing_init_dentry();
+	if (IS_ERR(d_tracer)) {
+		err = PTR_ERR(d_tracer);
+		goto err;
+	}
+
+	entry = tracefs_create_file("synthetic_events", 0644, d_tracer,
+				    tr, &synth_events_fops);
+	if (!entry) {
+		err = -ENODEV;
+		goto err;
+	}
+
+	return err;
+ err:
+	pr_warn("Could not create tracefs 'synthetic_events' entry\n");
+
+	return err;
+}
+
+fs_initcall(trace_events_hist_init);
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675174 — [PATCH 12/32] tracing: Add hist trigger timestamp support

Add support for a timestamp event field.  This is actually a 'pseudo-'
event field in that it behaves like it's part of the event record, but
is really part of the corresponding ring buffer event.

To make use of the timestamp field, users can specify
"$common_timestamp" as a field name for any histogram.  Note that this
doesn't make much sense on its own either as either a key or value,
but needs to be supported even so, since follow-on patches will add
support for making use of this field in time deltas.  The '$' is used
as a prefix on the variable name to indicate that it's not an bonafide
event field - so you won't find it in the event description - but
rather it's a synthetic field that can be used like a real field).

Note that the use of this field requires the ring buffer be put into
TIME_EXTEND_ABS mode, which saves the complete timestamp for each
event rather than an offset.  This mode will be enabled if and only if
a histogram makes use of the "$common_timestamp" field.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 90 +++++++++++++++++++++++++++++-----------
 1 file changed, 66 insertions(+), 24 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index dab6ff6..aeae3b4 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -89,6 +89,12 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event,
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
 
+static u64 hist_field_timestamp(struct hist_field *hist_field, void *event,
+				struct ring_buffer_event *rbe)
+{
+	return ring_buffer_event_time_stamp(rbe);
+}
+
 #define DEFINE_HIST_FIELD_FN(type)					\
 	static u64 hist_field_##type(struct hist_field *hist_field,	\
 				     void *event,			\
@@ -135,6 +141,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_SYSCALL		= 128,
 	HIST_FIELD_FL_STACKTRACE	= 256,
 	HIST_FIELD_FL_LOG2		= 512,
+	HIST_FIELD_FL_TIMESTAMP		= 1024,
 };
 
 struct hist_trigger_attrs {
@@ -159,6 +166,7 @@ struct hist_trigger_data {
 	struct trace_event_file		*event_file;
 	struct hist_trigger_attrs	*attrs;
 	struct tracing_map		*map;
+	bool				enable_timestamps;
 };
 
 static const char *hist_field_name(struct hist_field *field,
@@ -173,6 +181,8 @@ static const char *hist_field_name(struct hist_field *field,
 		field_name = field->field->name;
 	else if (field->flags & HIST_FIELD_FL_LOG2)
 		field_name = hist_field_name(field->operands[0], ++level);
+	else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
+		field_name = "$common_timestamp";
 
 	if (field_name == NULL)
 		field_name = "";
@@ -435,6 +445,12 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 		goto out;
 	}
 
+	if (flags & HIST_FIELD_FL_TIMESTAMP) {
+		hist_field->fn = hist_field_timestamp;
+		hist_field->size = sizeof(u64);
+		goto out;
+	}
+
 	if (WARN_ON_ONCE(!field))
 		goto out;
 
@@ -512,10 +528,15 @@ static int create_val_field(struct hist_trigger_data *hist_data,
 		}
 	}
 
-	field = trace_find_event_field(file->event_call, field_name);
-	if (!field) {
-		ret = -EINVAL;
-		goto out;
+	if (strcmp(field_name, "$common_timestamp") == 0) {
+		flags |= HIST_FIELD_FL_TIMESTAMP;
+		hist_data->enable_timestamps = true;
+	} else {
+		field = trace_find_event_field(file->event_call, field_name);
+		if (!field) {
+			ret = -EINVAL;
+			goto out;
+		}
 	}
 
 	hist_data->fields[val_idx] = create_hist_field(field, flags);
@@ -610,16 +631,22 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 			}
 		}
 
-		field = trace_find_event_field(file->event_call, field_name);
-		if (!field) {
-			ret = -EINVAL;
-			goto out;
-		}
+		if (strcmp(field_name, "$common_timestamp") == 0) {
+			flags |= HIST_FIELD_FL_TIMESTAMP;
+			hist_data->enable_timestamps = true;
+			key_size = sizeof(u64);
+		} else {
+			field = trace_find_event_field(file->event_call, field_name);
+			if (!field) {
+				ret = -EINVAL;
+				goto out;
+			}
 
-		if (is_string_field(field))
-			key_size = MAX_FILTER_STR_VAL;
-		else
-			key_size = field->size;
+			if (is_string_field(field))
+				key_size = MAX_FILTER_STR_VAL;
+			else
+				key_size = field->size;
+		}
 	}
 
 	hist_data->fields[key_idx] = create_hist_field(field, flags);
@@ -756,7 +783,7 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 			break;
 		}
 
-		if (strcmp(field_name, "hitcount") == 0) {
+		if ((strcmp(field_name, "hitcount") == 0)) {
 			descending = is_descending(field_str);
 			if (descending < 0) {
 				ret = descending;
@@ -816,6 +843,9 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 
 			if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
 				cmp_fn = tracing_map_cmp_none;
+			else if (!field)
+				cmp_fn = tracing_map_cmp_num(hist_field->size,
+							     hist_field->is_signed);
 			else if (is_string_field(field))
 				cmp_fn = tracing_map_cmp_string;
 			else
@@ -1213,7 +1243,11 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 {
 	const char *field_name = hist_field_name(hist_field, 0);
 
-	seq_printf(m, "%s", field_name);
+	if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
+		seq_puts(m, "$common_timestamp");
+	else if (field_name)
+		seq_printf(m, "%s", field_name);
+
 	if (hist_field->flags) {
 		const char *flags_str = get_hist_field_flags(hist_field);
 
@@ -1264,27 +1298,25 @@ static int event_hist_trigger_print(struct seq_file *m,
 
 	for (i = 0; i < hist_data->n_sort_keys; i++) {
 		struct tracing_map_sort_key *sort_key;
+		unsigned int idx;
 
 		sort_key = &hist_data->sort_keys[i];
+		idx = sort_key->field_idx;
+
+		if (WARN_ON(idx >= TRACING_MAP_FIELDS_MAX))
+			return -EINVAL;
 
 		if (i > 0)
 			seq_puts(m, ",");
 
-		if (sort_key->field_idx == HITCOUNT_IDX)
+		if (idx == HITCOUNT_IDX)
 			seq_puts(m, "hitcount");
-		else {
-			unsigned int idx = sort_key->field_idx;
-
-			if (WARN_ON(idx >= TRACING_MAP_FIELDS_MAX))
-				return -EINVAL;
-
+		else
 			hist_field_print(m, hist_data->fields[idx]);
-		}
 
 		if (sort_key->descending)
 			seq_puts(m, ".descending");
 	}
-
 	seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits));
 
 	if (data->filter_str)
@@ -1452,6 +1484,10 @@ static bool hist_trigger_match(struct event_trigger_data *data,
 			return false;
 		if (key_field->offset != key_field_test->offset)
 			return false;
+		if (key_field->size != key_field_test->size)
+			return false;
+		if (key_field->is_signed != key_field_test->is_signed)
+			return false;
 	}
 
 	for (i = 0; i < hist_data->n_sort_keys; i++) {
@@ -1534,6 +1570,9 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 
 	update_cond_flag(file);
 
+	if (hist_data->enable_timestamps)
+		tracing_set_time_stamp_abs(file->tr, true);
+
 	if (trace_event_trigger_enable_disable(file, 1) < 0) {
 		list_del_rcu(&data->list);
 		update_cond_flag(file);
@@ -1568,6 +1607,9 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
 
 	if (unregistered && test->ops->free)
 		test->ops->free(test->ops, test);
+
+	if (hist_data->enable_timestamps)
+		tracing_set_time_stamp_abs(file->tr, false);
 }
 
 static void hist_unreg_all(struct trace_event_file *file)
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675175 — [PATCH 18/32] tracing: Add simple expression support to hist triggers

Add support for simple addition, subtraction, and unary expressions
(-(expr) and expr, where expr = b-a, a+b, a+b+c) to hist triggers, in
order to support a minimal set of useful inter-event calculations.

These operations are needed for calculating latencies between events
(timestamp1-timestamp0) and for combined latencies (latencies over 3
or more events).

In the process, factor out some common code from key and value
parsing.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 457 +++++++++++++++++++++++++++++++++------
 1 file changed, 390 insertions(+), 67 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index fa8f607..92a9d89 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -32,6 +32,13 @@ typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event,
 #define HIST_FIELD_OPERANDS_MAX	2
 #define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)
 
+enum field_op_id {
+	FIELD_OP_NONE,
+	FIELD_OP_PLUS,
+	FIELD_OP_MINUS,
+	FIELD_OP_UNARY_MINUS,
+};
+
 struct hist_var {
 	char				*name;
 	struct hist_trigger_data	*hist_data;
@@ -48,6 +55,8 @@ struct hist_field {
 	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];
 	struct hist_trigger_data	*hist_data;
 	struct hist_var			var;
+	enum field_op_id		operator;
+	char				*name;
 };
 
 static u64 hist_field_none(struct hist_field *field, void *event,
@@ -98,6 +107,41 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event,
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
 
+static u64 hist_field_plus(struct hist_field *hist_field, void *event,
+			   struct ring_buffer_event *rbe)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, event, rbe);
+	u64 val2 = operand2->fn(operand2, event, rbe);
+
+	return val1 + val2;
+}
+
+static u64 hist_field_minus(struct hist_field *hist_field, void *event,
+			    struct ring_buffer_event *rbe)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, event, rbe);
+	u64 val2 = operand2->fn(operand2, event, rbe);
+
+	return val1 - val2;
+}
+
+static u64 hist_field_unary_minus(struct hist_field *hist_field, void *event,
+				  struct ring_buffer_event *rbe)
+{
+	struct hist_field *operand = hist_field->operands[0];
+
+	s64 sval = (s64)operand->fn(operand, event, rbe);
+	u64 val = (u64)-sval;
+
+	return val;
+}
+
 #define DEFINE_HIST_FIELD_FN(type)					\
 	static u64 hist_field_##type(struct hist_field *hist_field,	\
 				     void *event,			\
@@ -148,6 +192,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_TIMESTAMP_USECS	= 2048,
 	HIST_FIELD_FL_VAR		= 4096,
 	HIST_FIELD_FL_VAR_ONLY		= 8192,
+	HIST_FIELD_FL_EXPR		= 16384,
 };
 
 struct hist_trigger_attrs {
@@ -210,6 +255,8 @@ static const char *hist_field_name(struct hist_field *field,
 		field_name = hist_field_name(field->operands[0], ++level);
 	else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
 		field_name = "$common_timestamp";
+	else if (field->flags & HIST_FIELD_FL_EXPR)
+		field_name = field->name;
 
 	if (field_name == NULL)
 		field_name = "";
@@ -444,6 +491,73 @@ static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
 	.elt_init	= hist_trigger_elt_comm_init,
 };
 
+static char *expr_str(struct hist_field *field, unsigned int level)
+{
+	char *expr = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+
+	if (!expr || level > 1)
+		return NULL;
+
+	if (field->operator == FIELD_OP_UNARY_MINUS) {
+		char *subexpr;
+
+		strcat(expr, "-(");
+		subexpr = expr_str(field->operands[0], ++level);
+		if (!subexpr) {
+			kfree(expr);
+			return NULL;
+		}
+		strcat(expr, subexpr);
+		strcat(expr, ")");
+
+		return expr;
+	}
+
+	strcat(expr, hist_field_name(field->operands[0], 0));
+
+	switch (field->operator) {
+	case FIELD_OP_MINUS:
+		strcat(expr, "-");
+		break;
+	case FIELD_OP_PLUS:
+		strcat(expr, "+");
+		break;
+	default:
+		kfree(expr);
+		return NULL;
+	}
+
+	strcat(expr, hist_field_name(field->operands[1], 0));
+
+	return expr;
+}
+
+static int contains_operator(char *str)
+{
+	enum field_op_id field_op = FIELD_OP_NONE;
+	char *op;
+
+	op = strpbrk(str, "+-");
+	if (!op)
+		return FIELD_OP_NONE;
+
+	switch (*op) {
+	case '-':
+		if (*str == '-')
+			field_op = FIELD_OP_UNARY_MINUS;
+		else
+			field_op = FIELD_OP_MINUS;
+		break;
+	case '+':
+		field_op = FIELD_OP_PLUS;
+		break;
+	default:
+		break;
+	}
+
+	return field_op;
+}
+
 static void destroy_hist_field(struct hist_field *hist_field,
 			       unsigned int level)
 {
@@ -459,6 +573,7 @@ static void destroy_hist_field(struct hist_field *hist_field,
 		destroy_hist_field(hist_field->operands[i], ++level);
 
 	kfree(hist_field->var.name);
+	kfree(hist_field->name);
 
 	kfree(hist_field);
 }
@@ -479,6 +594,9 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 
 	hist_field->hist_data = hist_data;
 
+	if (flags & HIST_FIELD_FL_EXPR)
+		goto out; /* caller will populate */
+
 	if (flags & HIST_FIELD_FL_HITCOUNT) {
 		hist_field->fn = hist_field_counter;
 		goto out;
@@ -551,6 +669,247 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data)
 	}
 }
 
+static struct ftrace_event_field *
+parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
+	    char *field_str, unsigned long *flags)
+{
+	struct ftrace_event_field *field = NULL;
+	char *field_name;
+
+	field_name = strsep(&field_str, ".");
+	if (field_str) {
+		if (strcmp(field_str, "hex") == 0)
+			*flags |= HIST_FIELD_FL_HEX;
+		else if (strcmp(field_str, "sym") == 0)
+			*flags |= HIST_FIELD_FL_SYM;
+		else if (strcmp(field_str, "sym-offset") == 0)
+			*flags |= HIST_FIELD_FL_SYM_OFFSET;
+		else if ((strcmp(field_str, "execname") == 0) &&
+			 (strcmp(field_name, "common_pid") == 0))
+			*flags |= HIST_FIELD_FL_EXECNAME;
+		else if (strcmp(field_str, "syscall") == 0)
+			*flags |= HIST_FIELD_FL_SYSCALL;
+		else if (strcmp(field_str, "log2") == 0)
+			*flags |= HIST_FIELD_FL_LOG2;
+		else if (strcmp(field_str, "usecs") == 0)
+			*flags |= HIST_FIELD_FL_TIMESTAMP_USECS;
+		else
+			return ERR_PTR(-EINVAL);
+	}
+
+	if (strcmp(field_name, "$common_timestamp") == 0) {
+		*flags |= HIST_FIELD_FL_TIMESTAMP;
+		hist_data->enable_timestamps = true;
+		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
+			hist_data->attrs->ts_in_usecs = true;
+	} else {
+		field = trace_find_event_field(file->event_call, field_name);
+		if (!field)
+			return ERR_PTR(-EINVAL);
+	}
+
+	return field;
+}
+
+struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
+			      struct trace_event_file *file, char *str,
+			      unsigned long *flags, char *var_name)
+{
+	struct ftrace_event_field *field = NULL;
+	struct hist_field *hist_field = NULL;
+	int ret = 0;
+
+	field = parse_field(hist_data, file, str, flags);
+	if (IS_ERR(field)) {
+		ret = PTR_ERR(field);
+		goto out;
+	}
+
+	hist_field = create_hist_field(hist_data, field, *flags, var_name);
+	if (!hist_field) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	return hist_field;
+ out:
+	return ERR_PTR(ret);
+}
+
+static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *str, unsigned long flags,
+				     char *var_name, unsigned int level);
+
+static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
+				      struct trace_event_file *file,
+				      char *str, unsigned long flags,
+				      char *var_name, unsigned int level)
+{
+	struct hist_field *operand1, *expr = NULL;
+	unsigned long operand_flags;
+	char *operand1_str;
+	int ret = 0;
+	char *s;
+
+	// we support only -(xxx) i.e. explicit parens required
+
+	if (level > 2) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	str++; // skip leading '-'
+
+	s = strchr(str, '(');
+	if (s)
+		str++;
+	else {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	s = strchr(str, ')');
+	if (s)
+		*s = '\0';
+	else {
+		ret = -EINVAL; // no closing ')'
+		goto free;
+	}
+
+	operand1_str = strsep(&str, "(");
+	if (!operand1_str)
+		goto free;
+
+	flags |= HIST_FIELD_FL_EXPR;
+	expr = create_hist_field(hist_data, NULL, flags, var_name);
+	if (!expr) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	operand_flags = 0;
+	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	if (IS_ERR(operand1)) {
+		ret = PTR_ERR(operand1);
+		goto free;
+	}
+
+	if (operand1 == NULL) {
+		operand_flags = 0;
+		operand1 = parse_atom(hist_data, file, operand1_str,
+				      &operand_flags, NULL);
+		if (IS_ERR(operand1)) {
+			ret = PTR_ERR(operand1);
+			goto free;
+		}
+	}
+
+	expr->fn = hist_field_unary_minus;
+	expr->operands[0] = operand1;
+	expr->operator = FIELD_OP_UNARY_MINUS;
+	expr->name = expr_str(expr, 0);
+
+	return expr;
+ free:
+	return ERR_PTR(ret);
+}
+
+static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *str, unsigned long flags,
+				     char *var_name, unsigned int level)
+{
+	struct hist_field *operand1 = NULL, *operand2 = NULL, *expr = NULL;
+	unsigned long operand_flags;
+	int field_op, ret = -EINVAL;
+	char *sep, *operand1_str;
+
+	if (level > 2)
+		return NULL;
+
+	field_op = contains_operator(str);
+	if (field_op == FIELD_OP_NONE)
+		return NULL;
+
+	if (field_op == FIELD_OP_UNARY_MINUS)
+		return parse_unary(hist_data, file, str, flags, var_name, ++level);
+
+	switch (field_op) {
+	case FIELD_OP_MINUS:
+		sep = "-";
+		break;
+	case FIELD_OP_PLUS:
+		sep = "+";
+		break;
+	default:
+		goto free;
+	}
+
+	operand1_str = strsep(&str, sep);
+	if (!operand1_str || !str)
+		goto free;
+
+	operand_flags = 0;
+	operand1 = parse_atom(hist_data, file, operand1_str,
+			      &operand_flags, NULL);
+	if (IS_ERR(operand1)) {
+		ret = PTR_ERR(operand1);
+		operand1 = NULL;
+		goto free;
+	}
+
+	// rest of string could be another expression e.g. b+c in a+b+c
+	operand_flags = 0;
+	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	if (IS_ERR(operand2)) {
+		ret = PTR_ERR(operand2);
+		operand2 = NULL;
+		goto free;
+	}
+	if (!operand2) {
+		operand_flags = 0;
+		operand2 = parse_atom(hist_data, file, str,
+				      &operand_flags, NULL);
+		if (IS_ERR(operand2)) {
+			ret = PTR_ERR(operand2);
+			operand2 = NULL;
+			goto free;
+		}
+	}
+
+	flags |= HIST_FIELD_FL_EXPR;
+	expr = create_hist_field(hist_data, NULL, flags, var_name);
+	if (!expr) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	expr->operands[0] = operand1;
+	expr->operands[1] = operand2;
+	expr->operator = field_op;
+	expr->name = expr_str(expr, 0);
+
+	switch (field_op) {
+	case FIELD_OP_MINUS:
+		expr->fn = hist_field_minus;
+		break;
+	case FIELD_OP_PLUS:
+		expr->fn = hist_field_plus;
+		break;
+	default:
+		goto free;
+	}
+
+	return expr;
+ free:
+	destroy_hist_field(operand1, 0);
+	destroy_hist_field(operand2, 0);
+	destroy_hist_field(expr, 0);
+
+	return ERR_PTR(ret);
+}
+
 static int create_hitcount_val(struct hist_trigger_data *hist_data)
 {
 	hist_data->fields[HITCOUNT_IDX] =
@@ -609,9 +968,9 @@ static int create_val_field(struct hist_trigger_data *hist_data,
 			    struct trace_event_file *file,
 			    char *field_str, bool var_only)
 {
-	struct ftrace_event_field *field = NULL;
-	char *field_name, *var_name;
+	struct hist_field *hist_field;
 	unsigned long flags = 0;
+	char *var_name;
 	int ret = 0;
 
 	if (WARN_ON(!var_only && val_idx >= TRACING_MAP_VALS_MAX))
@@ -642,37 +1001,27 @@ static int create_val_field(struct hist_trigger_data *hist_data,
 		goto out;
 	}
 
-	field_name = strsep(&field_str, ".");
-	if (field_str) {
-		if (strcmp(field_str, "hex") == 0)
-			flags |= HIST_FIELD_FL_HEX;
-		else {
-			ret = -EINVAL;
-			goto out;
-		}
+	hist_field = parse_expr(hist_data, file, field_str, flags, var_name, 0);
+	if (IS_ERR(hist_field)) {
+		ret = PTR_ERR(hist_field);
+		goto out;
 	}
 
-	if (strcmp(field_name, "$common_timestamp") == 0) {
-		flags |= HIST_FIELD_FL_TIMESTAMP;
-		hist_data->enable_timestamps = true;
-	} else {
-		field = trace_find_event_field(file->event_call, field_name);
-		if (!field) {
-			ret = -EINVAL;
+	if (!hist_field) {
+		hist_field = parse_atom(hist_data, file, field_str,
+					&flags, var_name);
+		if (IS_ERR(hist_field)) {
+			ret = PTR_ERR(hist_field);
 			goto out;
 		}
 	}
 
-	hist_data->fields[val_idx] = create_hist_field(hist_data, field, flags, var_name);
-	if (!hist_data->fields[val_idx]) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	hist_data->fields[val_idx] = hist_field;
 
 	++hist_data->n_vals;
 	++hist_data->n_fields;
 
-	if (hist_data->fields[val_idx]->flags & HIST_FIELD_FL_VAR_ONLY)
+	if (hist_field->flags & HIST_FIELD_FL_VAR_ONLY)
 		hist_data->n_var_only++;
 
 	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX + TRACING_MAP_VARS_MAX))
@@ -726,8 +1075,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 			    struct trace_event_file *file,
 			    char *field_str)
 {
-	struct ftrace_event_field *field = NULL;
 	struct hist_field *hist_field = NULL;
+
 	unsigned long flags = 0;
 	unsigned int key_size;
 	char *var_name;
@@ -754,60 +1103,33 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 		key_size = sizeof(unsigned long) * HIST_STACKTRACE_DEPTH;
 		hist_field = create_hist_field(hist_data, NULL, flags, var_name);
 	} else {
-		char *field_name = strsep(&field_str, ".");
-
-		if (field_str) {
-			if (strcmp(field_str, "hex") == 0)
-				flags |= HIST_FIELD_FL_HEX;
-			else if (strcmp(field_str, "sym") == 0)
-				flags |= HIST_FIELD_FL_SYM;
-			else if (strcmp(field_str, "sym-offset") == 0)
-				flags |= HIST_FIELD_FL_SYM_OFFSET;
-			else if ((strcmp(field_str, "execname") == 0) &&
-				 (strcmp(field_name, "common_pid") == 0))
-				flags |= HIST_FIELD_FL_EXECNAME;
-			else if (strcmp(field_str, "syscall") == 0)
-				flags |= HIST_FIELD_FL_SYSCALL;
-			else if (strcmp(field_str, "log2") == 0)
-				flags |= HIST_FIELD_FL_LOG2;
-			else if (strcmp(field_str, "usecs") == 0)
-				flags |= HIST_FIELD_FL_TIMESTAMP_USECS;
-			else {
-				ret = -EINVAL;
-				goto out;
-			}
+		hist_field = parse_expr(hist_data, file, field_str, flags,
+					var_name, 0);
+		if (IS_ERR(hist_field)) {
+			ret = PTR_ERR(hist_field);
+			goto out;
 		}
 
-		if (strcmp(field_name, "$common_timestamp") == 0) {
-			flags |= HIST_FIELD_FL_TIMESTAMP;
-			hist_data->enable_timestamps = true;
-			if (flags & HIST_FIELD_FL_TIMESTAMP_USECS)
-				hist_data->attrs->ts_in_usecs = true;
-			key_size = sizeof(u64);
-		} else {
-			field = trace_find_event_field(file->event_call, field_name);
-			if (!field) {
-				ret = -EINVAL;
+		if (!hist_field) {
+			hist_field = parse_atom(hist_data, file, field_str,
+						&flags, var_name);
+			if (IS_ERR(hist_field)) {
+				ret = PTR_ERR(hist_field);
 				goto out;
 			}
-
-			if (is_string_field(field))
-				key_size = MAX_FILTER_STR_VAL;
-			else
-				key_size = field->size;
 		}
-	}
 
-	hist_data->fields[key_idx] = create_hist_field(hist_data, field, flags, var_name);
-	if (!hist_data->fields[key_idx]) {
-		ret = -ENOMEM;
-		goto out;
+		key_size = hist_field->size;
 	}
 
+	hist_data->fields[key_idx] = hist_field;
+
 	key_size = ALIGN(key_size, sizeof(u64));
 	hist_data->fields[key_idx]->size = key_size;
 	hist_data->fields[key_idx]->offset = key_offset;
+
 	hist_data->key_size += key_size;
+
 	if (hist_data->key_size > HIST_KEY_SIZE_MAX) {
 		ret = -EINVAL;
 		goto out;
@@ -1330,7 +1652,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 	for (i = 1; i < hist_data->n_vals; i++) {
 		field_name = hist_field_name(hist_data->fields[i], 0);
 
-		if (hist_data->fields[i]->flags & HIST_FIELD_FL_VAR)
+		if (hist_data->fields[i]->flags & HIST_FIELD_FL_VAR ||
+		    hist_data->fields[i]->flags & HIST_FIELD_FL_EXPR)
 			continue;
 
 		if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675176 — [PATCH 08/32] tracing: Break out hist trigger assignment parsing

This will make it easier to add variables, and makes the parsing code
cleaner regardless.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 56 +++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 613ff05..fccbffe 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -251,6 +251,35 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 	kfree(attrs);
 }
 
+static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
+{
+	int ret = 0;
+
+	if ((strncmp(str, "key=", strlen("key=")) == 0) ||
+	    (strncmp(str, "keys=", strlen("keys=")) == 0))
+		attrs->keys_str = kstrdup(str, GFP_KERNEL);
+	else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
+		 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
+		 (strncmp(str, "values=", strlen("values=")) == 0))
+		attrs->vals_str = kstrdup(str, GFP_KERNEL);
+	else if (strncmp(str, "sort=", strlen("sort=")) == 0)
+		attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+	else if (strncmp(str, "name=", strlen("name=")) == 0)
+		attrs->name = kstrdup(str, GFP_KERNEL);
+	else if (strncmp(str, "size=", strlen("size=")) == 0) {
+		int map_bits = parse_map_size(str);
+
+		if (map_bits < 0) {
+			ret = map_bits;
+			goto out;
+		}
+		attrs->map_bits = map_bits;
+	} else
+		ret = -EINVAL;
+ out:
+	return ret;
+}
+
 static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 {
 	struct hist_trigger_attrs *attrs;
@@ -263,33 +292,18 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 	while (trigger_str) {
 		char *str = strsep(&trigger_str, ":");
 
-		if ((strncmp(str, "key=", strlen("key=")) == 0) ||
-		    (strncmp(str, "keys=", strlen("keys=")) == 0))
-			attrs->keys_str = kstrdup(str, GFP_KERNEL);
-		else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
-			 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
-			 (strncmp(str, "values=", strlen("values=")) == 0))
-			attrs->vals_str = kstrdup(str, GFP_KERNEL);
-		else if (strncmp(str, "sort=", strlen("sort=")) == 0)
-			attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
-		else if (strncmp(str, "name=", strlen("name=")) == 0)
-			attrs->name = kstrdup(str, GFP_KERNEL);
-		else if (strcmp(str, "pause") == 0)
+		if (strchr(str, '=')) {
+			ret = parse_assignment(str, attrs);
+			if (ret)
+				goto free;
+		} else if (strcmp(str, "pause") == 0)
 			attrs->pause = true;
 		else if ((strcmp(str, "cont") == 0) ||
 			 (strcmp(str, "continue") == 0))
 			attrs->cont = true;
 		else if (strcmp(str, "clear") == 0)
 			attrs->clear = true;
-		else if (strncmp(str, "size=", strlen("size=")) == 0) {
-			int map_bits = parse_map_size(str);
-
-			if (map_bits < 0) {
-				ret = map_bits;
-				goto free;
-			}
-			attrs->map_bits = map_bits;
-		} else {
+		else {
 			ret = -EINVAL;
 			goto free;
 		}
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675177 — [PATCH 15/32] tracing: Add usecs modifier for hist trigger timestamps

Appending .usecs onto a common_timestamp field will cause the
timestamp value to be in microseconds instead of the default
nanoseconds.  A typical latency histogram using usecs would look like
this:

   # echo 'hist:keys=pid,prio:ts0=$common_timestamp.usecs ...
   # echo 'hist:keys=next_pid:wakeup_lat=$common_timestamp.usecs-$ts0 ...

This also adds an external trace_clock_in_ns() to trace.c for the
timestamp conversion.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace.c             |  8 ++++++++
 kernel/trace/trace.h             |  2 ++
 kernel/trace/trace_events_hist.c | 28 ++++++++++++++++++++++------
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f66a3df..ec84822 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1170,6 +1170,14 @@ unsigned long nsecs_to_usecs(unsigned long nsecs)
 	ARCH_TRACE_CLOCKS
 };
 
+bool trace_clock_in_ns(struct trace_array *tr)
+{
+	if (trace_clocks[tr->clock_id].in_ns)
+		return true;
+
+	return false;
+}
+
 /*
  * trace_parser_get_init - gets the buffer for trace parser
  */
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 81b1d07..65f90b4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -283,6 +283,8 @@ enum {
 
 extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
 
+extern bool trace_clock_in_ns(struct trace_array *tr);
+
 /*
  * The global tracer (top) should be the first trace array added,
  * but we check the flag anyway.
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index fb08a75..5c351d7 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -90,12 +90,6 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event,
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
 
-static u64 hist_field_timestamp(struct hist_field *hist_field, void *event,
-				struct ring_buffer_event *rbe)
-{
-	return ring_buffer_event_time_stamp(rbe);
-}
-
 #define DEFINE_HIST_FIELD_FN(type)					\
 	static u64 hist_field_##type(struct hist_field *hist_field,	\
 				     void *event,			\
@@ -143,6 +137,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_STACKTRACE	= 256,
 	HIST_FIELD_FL_LOG2		= 512,
 	HIST_FIELD_FL_TIMESTAMP		= 1024,
+	HIST_FIELD_FL_TIMESTAMP_USECS	= 2048,
 };
 
 struct hist_trigger_attrs {
@@ -153,6 +148,7 @@ struct hist_trigger_attrs {
 	bool		pause;
 	bool		cont;
 	bool		clear;
+	bool		ts_in_usecs;
 	unsigned int	map_bits;
 };
 
@@ -170,6 +166,20 @@ struct hist_trigger_data {
 	bool				enable_timestamps;
 };
 
+static u64 hist_field_timestamp(struct hist_field *hist_field, void *event,
+				struct ring_buffer_event *rbe)
+{
+	struct hist_trigger_data *hist_data = hist_field->hist_data;
+	struct trace_array *tr = hist_data->event_file->tr;
+
+	u64 ts = ring_buffer_event_time_stamp(rbe);
+
+	if (hist_data->attrs->ts_in_usecs && trace_clock_in_ns(tr))
+		ts = ns2usecs(ts);
+
+	return ts;
+}
+
 static const char *hist_field_name(struct hist_field *field,
 				   unsigned int level)
 {
@@ -629,6 +639,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 				flags |= HIST_FIELD_FL_SYSCALL;
 			else if (strcmp(field_str, "log2") == 0)
 				flags |= HIST_FIELD_FL_LOG2;
+			else if (strcmp(field_str, "usecs") == 0)
+				flags |= HIST_FIELD_FL_TIMESTAMP_USECS;
 			else {
 				ret = -EINVAL;
 				goto out;
@@ -638,6 +650,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 		if (strcmp(field_name, "$common_timestamp") == 0) {
 			flags |= HIST_FIELD_FL_TIMESTAMP;
 			hist_data->enable_timestamps = true;
+			if (flags & HIST_FIELD_FL_TIMESTAMP_USECS)
+				hist_data->attrs->ts_in_usecs = true;
 			key_size = sizeof(u64);
 		} else {
 			field = trace_find_event_field(file->event_call, field_name);
@@ -1239,6 +1253,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 		flags_str = "syscall";
 	else if (hist_field->flags & HIST_FIELD_FL_LOG2)
 		flags_str = "log2";
+	else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP_USECS)
+		flags_str = "usecs";
 
 	return flags_str;
 }
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675178 — [PATCH 23/32] tracing: Add 'onmatch' hist trigger action support

Add an 'onmatch(matching.event).<synthetic_event_name>(param list)'
hist trigger action which is invoked with the set of variables or
event fields named in the 'param list'.  The result is the generation
of a synthetic event that consists of the values contained in those
variables and/or fields at the time the invoking event was hit.

As an example the below defines a simple synthetic event using a
variable defined on the sched_wakeup_new event, and shows the event
definition with unresolved fields, since the sched_wakeup_new event
with the testpid variable hasn't been defined yet:

    # echo 'wakeup_new_test pid_t pid; int prio' >> \
      /sys/kernel/debug/tracing/synthetic_events

    # cat /sys/kernel/debug/tracing/synthetic_events
      wakeup_new_test pid_t pid; int prio

The following hist trigger both defines a testpid variable and
specifies an onmatch() trace action that uses that variable along with
a non-variable field to generate a wakeup_new_test synthetic event
whenever a sched_wakeup_new event occurs, which because of the 'if
comm == "cyclictest"' filter only happens when the executable is
cyclictest:

    # echo 'hist:keys=testpid=pid:\
      onmatch(sched.sched_wakeup_new).wakeup_new_test($testpid, prio) \
        if comm=="cyclictest"' >> \
      /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger

Creating and displaying a histogram based on those events is now just
a matter of using the fields and new synthetic event in the
tracing/events/synthetic directory, as usual:

    # echo 'hist:keys=pid,prio:sort=pid,prio' >> \
      /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 955 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 940 insertions(+), 15 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index e11b3a3..b1f859c 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -59,6 +59,7 @@ struct hist_field {
 	unsigned int			size;
 	unsigned int			offset;
 	unsigned int                    is_signed;
+	const char			*type;
 	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];
 	struct hist_trigger_data	*hist_data;
 	struct hist_var			var;
@@ -243,6 +244,16 @@ struct hist_trigger_attrs {
 	unsigned int	n_actions;
 };
 
+struct field_var {
+	struct hist_field	*var;
+	struct hist_field	*val;
+};
+
+struct field_var_hist {
+	struct hist_trigger_data	*hist_data;
+	char				*cmd;
+};
+
 struct hist_trigger_data {
 	struct hist_field               *fields[HIST_FIELDS_MAX];
 	unsigned int			n_vals;
@@ -263,6 +274,14 @@ struct hist_trigger_data {
 
 	struct action_data		*actions[HIST_ACTIONS_MAX];
 	unsigned int			n_actions;
+
+	struct hist_field		*synth_var_refs[SYNTH_FIELDS_MAX];
+	unsigned int			n_synth_var_refs;
+	struct field_var		*field_vars[SYNTH_FIELDS_MAX];
+	unsigned int			n_field_vars;
+	unsigned int			n_field_var_str;
+	struct field_var_hist		*field_var_hists[SYNTH_FIELDS_MAX];
+	unsigned int			n_field_var_hists;
 };
 
 struct synth_field {
@@ -291,7 +310,14 @@ typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
 
 struct action_data {
 	action_fn_t		fn;
+	unsigned int		n_params;
+	char			*params[SYNTH_FIELDS_MAX];
+
 	unsigned int		var_ref_idx;
+	char			*match_event;
+	char			*match_event_system;
+	char			*synth_event_name;
+	struct synth_event	*synth_event;
 };
 
 static LIST_HEAD(synth_event_list);
@@ -802,6 +828,50 @@ static struct synth_event *alloc_synth_event(char *event_name, int n_fields,
 	return event;
 }
 
+static void action_trace(struct hist_trigger_data *hist_data,
+			 struct tracing_map_elt *elt, void *rec,
+			 struct ring_buffer_event *rbe,
+			 struct action_data *data, u64 *var_ref_vals)
+{
+	struct synth_event *event = data->synth_event;
+
+	trace_synth(event, var_ref_vals, data->var_ref_idx);
+}
+
+static bool check_hist_action_refs(struct hist_trigger_data *hist_data,
+				   struct synth_event *event)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == action_trace && data->synth_event == event)
+			return true;
+	}
+
+	return false;
+}
+
+static LIST_HEAD(hist_action_list);
+static LIST_HEAD(hist_var_list);
+
+struct hist_var_data {
+	struct list_head list;
+	struct hist_trigger_data *hist_data;
+};
+
+static bool check_synth_action_refs(struct synth_event *event)
+{
+	struct hist_var_data *var_data;
+
+	list_for_each_entry(var_data, &hist_action_list, list)
+		if (check_hist_action_refs(var_data->hist_data, event))
+			return true;
+
+	return false;
+}
+
 static int create_synth_event(int argc, char **argv)
 {
 	struct synth_field *fields[SYNTH_FIELDS_MAX];
@@ -832,15 +902,17 @@ static int create_synth_event(int argc, char **argv)
 	event = find_synth_event(name);
 	if (event) {
 		if (delete_event) {
+			if (check_synth_action_refs(event)) {
+				ret = -EBUSY;
+				goto out;
+			}
 			remove_synth_event(event);
 			goto err;
 		} else
 			ret = -EEXIST;
 		goto out;
-	} else if (delete_event) {
-		ret = -EINVAL;
+	} else if (delete_event)
 		goto out;
-	}
 
 	if (argc < 2) {
 		ret = -EINVAL;
@@ -891,11 +963,18 @@ static int release_all_synth_events(void)
 
 	mutex_lock(&synth_event_mutex);
 
+	list_for_each_entry(event, &synth_event_list, list) {
+		if (check_synth_action_refs(event)) {
+			ret = -EBUSY;
+			goto out;
+		}
+	}
+
 	list_for_each_entry_safe(event, e, &synth_event_list, list) {
 		remove_synth_event(event);
 		free_synth_event(event);
 	}
-
+ out:
 	mutex_unlock(&synth_event_mutex);
 
 	return ret;
@@ -992,13 +1071,6 @@ static u64 hist_field_timestamp(struct hist_field *hist_field,
 	return ts;
 }
 
-static LIST_HEAD(hist_var_list);
-
-struct hist_var_data {
-	struct list_head list;
-	struct hist_trigger_data *hist_data;
-};
-
 static struct hist_field *check_var_ref(struct hist_field *hist_field,
 					struct hist_trigger_data *var_data,
 					unsigned int var_idx)
@@ -1248,6 +1320,7 @@ static struct hist_field *find_event_var(const char *system,
 struct hist_elt_data {
 	char *comm;
 	u64 *var_ref_vals;
+	char *field_var_str[SYNTH_FIELDS_MAX];
 };
 
 static u64 hist_field_var_ref(struct hist_field *hist_field,
@@ -1415,11 +1488,21 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 
 static int parse_action(char *str, struct hist_trigger_attrs *attrs)
 {
-	int ret = 0;
+	int ret = -EINVAL;
 
 	if (attrs->n_actions >= HIST_ACTIONS_MAX)
 		return ret;
 
+	if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0)) {
+		attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
+		if (!attrs->action_str[attrs->n_actions]) {
+			ret = -ENOMEM;
+			return ret;
+		}
+		attrs->n_actions++;
+		ret = 0;
+	}
+
 	return ret;
 }
 
@@ -1525,7 +1608,14 @@ static inline void save_comm(char *comm, struct task_struct *task)
 
 static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)
 {
+	struct hist_trigger_data *hist_data = elt->map->private_data;
 	struct hist_elt_data *private_data = elt->private_data;
+	unsigned int i, n_str;
+
+	n_str = hist_data->n_field_var_str;
+
+	for (i = 0; i < n_str; i++)
+		kfree(private_data->field_var_str[i]);
 
 	kfree(private_data->comm);
 	kfree(private_data);
@@ -1537,7 +1627,7 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
 	unsigned int size = TASK_COMM_LEN + 1;
 	struct hist_elt_data *elt_data;
 	struct hist_field *key_field;
-	unsigned int i;
+	unsigned int i, n_str;
 
 	elt->private_data = elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
 	if (!elt_data)
@@ -1557,6 +1647,16 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
 		}
 	}
 
+	n_str = hist_data->n_field_var_str;
+
+	for (i = 0; i < n_str; i++) {
+		elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL);
+		if (!elt_data->field_var_str[i]) {
+			hist_trigger_elt_data_free(elt);
+			return -ENOMEM;
+		}
+	}
+
 	return 0;
 }
 
@@ -1674,6 +1774,7 @@ static void destroy_hist_field(struct hist_field *hist_field,
 
 	kfree(hist_field->var.name);
 	kfree(hist_field->name);
+	kfree(hist_field->type);
 
 	kfree(hist_field);
 }
@@ -1704,6 +1805,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 
 	if (flags & HIST_FIELD_FL_HITCOUNT) {
 		hist_field->fn = hist_field_counter;
+		hist_field->size = sizeof(u64);
+		hist_field->type = kstrdup("u64", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
@@ -1717,12 +1822,18 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		hist_field->fn = hist_field_log2;
 		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);
 		hist_field->size = hist_field->operands[0]->size;
+		hist_field->type = kstrdup(hist_field->operands[0]->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
 	if (flags & HIST_FIELD_FL_TIMESTAMP) {
 		hist_field->fn = hist_field_timestamp;
 		hist_field->size = sizeof(u64);
+		hist_field->type = kstrdup("u64", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
@@ -1731,6 +1842,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 
 	if (is_string_field(field)) {
 		flags |= HIST_FIELD_FL_STRING;
+		hist_field->size = MAX_FILTER_STR_VAL;
+		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 
 		if (field->filter_type == FILTER_STATIC_STRING)
 			hist_field->fn = hist_field_string;
@@ -1739,6 +1854,12 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		else
 			hist_field->fn = hist_field_pstring;
 	} else {
+		hist_field->size = field->size;
+		hist_field->is_signed = field->is_signed;
+		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+
 		hist_field->fn = select_value_fn(field->size,
 						 field->is_signed);
 		if (!hist_field->fn) {
@@ -1786,7 +1907,10 @@ static struct hist_field *create_var_ref(struct hist_field *var_field)
 		ref_field->size = var_field->size;
 		ref_field->is_signed = var_field->is_signed;
 		ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL);
-		if (!ref_field->name) {
+		ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
+		if (!ref_field->name || !ref_field->type) {
+			kfree(ref_field->name);
+			kfree(ref_field->type);
 			destroy_hist_field(ref_field, 0);
 			return NULL;
 		}
@@ -1970,6 +2094,11 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
 	expr->operands[0] = operand1;
 	expr->operator = FIELD_OP_UNARY_MINUS;
 	expr->name = expr_str(expr, 0);
+	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	if (!expr->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
 
 	return expr;
  free:
@@ -2053,6 +2182,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 	expr->operands[1] = operand2;
 	expr->operator = field_op;
 	expr->name = expr_str(expr, 0);
+	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	if (!expr->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
 
 	switch (field_op) {
 	case FIELD_OP_MINUS:
@@ -2074,6 +2208,718 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 	return ERR_PTR(ret);
 }
 
+static struct hist_var_data *find_actions(struct hist_trigger_data *hist_data)
+{
+	struct hist_var_data *var_data, *found = NULL;
+
+	list_for_each_entry(var_data, &hist_action_list, list) {
+		if (var_data->hist_data == hist_data) {
+			found = var_data;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static int save_hist_actions(struct hist_trigger_data *hist_data)
+{
+	struct hist_var_data *var_data;
+
+	var_data = find_actions(hist_data);
+	if (var_data)
+		return 0;
+
+	var_data = kzalloc(sizeof(*var_data), GFP_KERNEL);
+	if (!var_data)
+		return -ENOMEM;
+
+	var_data->hist_data = hist_data;
+	list_add(&var_data->list, &hist_action_list);
+
+	return 0;
+}
+
+static void remove_hist_actions(struct hist_trigger_data *hist_data)
+{
+	struct hist_var_data *var_data;
+
+	var_data = find_actions(hist_data);
+	if (!var_data)
+		return;
+
+	list_del(&var_data->list);
+
+	kfree(var_data);
+}
+
+static char *find_trigger_filter(struct hist_trigger_data *hist_data,
+				 struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (test->private_data == hist_data)
+				return test->filter_str;
+		}
+	}
+
+	return NULL;
+}
+
+static struct event_command trigger_hist_cmd;
+static int event_hist_trigger_func(struct event_command *cmd_ops,
+				   struct trace_event_file *file,
+				   char *glob, char *cmd, char *param);
+
+static bool compatible_keys(struct hist_trigger_data *target_hist_data,
+			    struct hist_trigger_data *hist_data,
+			    unsigned int n_keys)
+{
+	struct hist_field *target_hist_field, *hist_field;
+	unsigned int n, i, j;
+
+	if (hist_data->n_fields - hist_data->n_vals != n_keys)
+		return false;
+
+	i = hist_data->n_vals;
+	j = target_hist_data->n_vals;
+
+	for (n = 0; n < n_keys; n++) {
+		hist_field = hist_data->fields[i + n];
+		target_hist_field = hist_data->fields[j + n];
+
+		if (strcmp(hist_field->type, target_hist_field->type) != 0)
+			return false;
+		if (hist_field->size != target_hist_field->size)
+			return false;
+		if (hist_field->is_signed != target_hist_field->is_signed)
+			return false;
+	}
+
+	return true;
+}
+
+static struct hist_trigger_data *
+find_compatible_hist(struct hist_trigger_data *target_hist_data,
+		     struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data;
+	struct event_trigger_data *test;
+	unsigned int n_keys;
+
+	n_keys = target_hist_data->n_fields - target_hist_data->n_vals;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			hist_data = test->private_data;
+
+			if (compatible_keys(target_hist_data, hist_data, n_keys))
+				return hist_data;
+		}
+	}
+
+	return NULL;
+}
+
+static struct trace_event_file *event_file(char *system, char *event_name)
+{
+	struct trace_event_file *file;
+	struct trace_array *tr;
+
+	tr = top_trace_array();
+	if (!tr)
+		return ERR_PTR(-ENODEV);
+
+	file = find_event_file(tr, system, event_name);
+	if (!file)
+		return ERR_PTR(-EINVAL);
+
+	return file;
+}
+
+static struct hist_field *
+create_field_var_hist(struct hist_trigger_data *target_hist_data,
+		      char *system, char *event_name, char *field_name)
+{
+	struct hist_field *event_var = ERR_PTR(-EINVAL);
+	struct hist_trigger_data *hist_data;
+	unsigned int i, n, first = true;
+	struct field_var_hist *var_hist;
+	struct trace_event_file *file;
+	struct hist_field *key_field;
+	struct trace_array *tr;
+	char *saved_filter;
+	char *cmd;
+	int ret;
+
+	if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX)
+		return ERR_PTR(-EINVAL);
+
+	tr = top_trace_array();
+	if (!tr)
+		return ERR_PTR(-ENODEV);
+
+	file = event_file(system, event_name);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		return ERR_PTR(ret);
+	}
+
+	hist_data = find_compatible_hist(target_hist_data, file);
+	if (!hist_data)
+		return ERR_PTR(-EINVAL);
+
+	var_hist = kzalloc(sizeof(*var_hist), GFP_KERNEL);
+	if (!var_hist)
+		return ERR_PTR(-ENOMEM);
+
+	cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+	if (!cmd) {
+		kfree(var_hist);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	strcat(cmd, "keys=");
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+		if (!first)
+			strcat(cmd, ",");
+		strcat(cmd, key_field->field->name);
+		first = false;
+	}
+
+	strcat(cmd, ":synthetic_");
+	strcat(cmd, field_name);
+	strcat(cmd, "=");
+	strcat(cmd, field_name);
+
+	saved_filter = find_trigger_filter(hist_data, file);
+	if (saved_filter) {
+		strcat(cmd, " if ");
+		strcat(cmd, saved_filter);
+	}
+
+	var_hist->cmd = kstrdup(cmd, GFP_KERNEL);
+	if (!var_hist->cmd) {
+		kfree(cmd);
+		kfree(var_hist);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	var_hist->hist_data = hist_data;
+
+	ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+				      "", "hist", cmd);
+	if (ret) {
+		kfree(cmd);
+		kfree(var_hist->cmd);
+		kfree(var_hist);
+		return ERR_PTR(ret);
+	}
+
+	strcpy(cmd, "synthetic_");
+	strcat(cmd, field_name);
+
+	event_var = find_event_var(system, event_name, cmd);
+	if (!event_var) {
+		kfree(cmd);
+		kfree(var_hist->cmd);
+		kfree(var_hist);
+		return ERR_PTR(-EINVAL);
+	}
+
+	n = target_hist_data->n_field_var_hists;
+	target_hist_data->field_var_hists[n] = var_hist;
+	target_hist_data->n_field_var_hists++;
+
+	return event_var;
+}
+
+static struct hist_field *
+find_target_event_var(struct hist_trigger_data *hist_data,
+		      char *system, char *event_name, char *var_name)
+{
+	struct trace_event_file *file = hist_data->event_file;
+	struct hist_field *hist_field = NULL;
+
+	if (system) {
+		struct trace_event_call *call;
+
+		if (!event_name)
+			return NULL;
+
+		call = file->event_call;
+
+		if (strcmp(system, call->class->system) != 0)
+			return NULL;
+
+		if (strcmp(event_name, trace_event_name(call)) != 0)
+			return NULL;
+	}
+
+	hist_field = find_var_field(hist_data, var_name);
+
+	return hist_field;
+}
+
+static inline void __update_field_vars(struct tracing_map_elt *elt,
+				       struct ring_buffer_event *rbe,
+				       void *rec,
+				       struct field_var **field_vars,
+				       unsigned int n_field_vars,
+				       unsigned int field_var_str_start)
+{
+	struct hist_elt_data *elt_data = elt->private_data;
+	unsigned int i, j, var_idx;
+	u64 var_val;
+
+	for (i = 0, j = field_var_str_start; i < n_field_vars; i++) {
+		struct field_var *field_var = field_vars[i];
+		struct hist_field *var = field_var->var;
+		struct hist_field *val = field_var->val;
+
+		var_val = val->fn(val, elt, rbe, rec);
+		var_idx = var->var.idx;
+
+		if (val->flags & HIST_FIELD_FL_STRING) {
+			char *str = elt_data->field_var_str[j++];
+
+			memcpy(str, (char *)(uintptr_t)var_val,
+			       TASK_COMM_LEN + 1);
+			var_val = (u64)(uintptr_t)str;
+		}
+		tracing_map_set_var(elt, var_idx, var_val);
+	}
+}
+
+static void update_field_vars(struct hist_trigger_data *hist_data,
+			      struct tracing_map_elt *elt,
+			      struct ring_buffer_event *rbe,
+			      void *rec)
+{
+	__update_field_vars(elt, rbe, rec, hist_data->field_vars,
+			    hist_data->n_field_vars, 0);
+}
+
+static struct hist_field *create_var(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *name, int size, const char *type)
+{
+	struct hist_field *var;
+	int idx;
+
+	if (find_var(file, name) && !hist_data->remove) {
+		var = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	var = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
+	if (!var) {
+		var = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	idx = tracing_map_add_var(hist_data->map);
+	if (idx < 0) {
+		kfree(var);
+		var = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	var->flags = HIST_FIELD_FL_VAR;
+	var->var.idx = idx;
+	var->var.hist_data = var->hist_data = hist_data;
+	var->size = size;
+	var->var.name = kstrdup(name, GFP_KERNEL);
+	var->type = kstrdup(type, GFP_KERNEL);
+	if (!var->var.name || !var->type) {
+		kfree(var->var.name);
+		kfree(var->type);
+		kfree(var);
+		var = ERR_PTR(-ENOMEM);
+	}
+ out:
+	return var;
+}
+
+static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
+					  struct trace_event_file *file,
+					  char *field_name)
+{
+	struct hist_field *val = NULL, *var = NULL;
+	unsigned long flags = HIST_FIELD_FL_VAR;
+	struct field_var *field_var;
+	int ret = 0;
+
+	if (hist_data->n_field_vars >= SYNTH_FIELDS_MAX) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	val = parse_atom(hist_data, file, field_name, &flags, NULL);
+	if (IS_ERR(val)) {
+		ret = PTR_ERR(val);
+		goto err;
+	}
+
+	var = create_var(hist_data, file, field_name, val->size, val->type);
+	if (IS_ERR(var)) {
+		kfree(val);
+		ret = PTR_ERR(var);
+		goto err;
+	}
+
+	field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
+	if (!field_var) {
+		kfree(val);
+		kfree(var);
+		ret =  -ENOMEM;
+		goto err;
+	}
+
+	field_var->var = var;
+	field_var->val = val;
+ out:
+	return field_var;
+ err:
+	field_var = ERR_PTR(ret);
+	goto out;
+}
+
+static struct field_var *
+create_target_field_var(struct hist_trigger_data *hist_data,
+			char *system, char *event_name, char *var_name)
+{
+	struct trace_event_file *file = hist_data->event_file;
+
+	if (system) {
+		struct trace_event_call *call;
+
+		if (!event_name)
+			return NULL;
+
+		call = file->event_call;
+
+		if (strcmp(system, call->class->system) != 0)
+			return NULL;
+
+		if (strcmp(event_name, trace_event_name(call)) != 0)
+			return NULL;
+	}
+
+	return create_field_var(hist_data, file, var_name);
+}
+
+static void onmatch_destroy(struct action_data *data)
+{
+	unsigned int i;
+
+	kfree(data->match_event);
+	kfree(data->match_event_system);
+	kfree(data->synth_event_name);
+
+	for (i = 0; i < data->n_params; i++)
+		kfree(data->params[i]);
+
+	kfree(data);
+}
+
+static void destroy_field_var(struct field_var *field_var)
+{
+	if (!field_var)
+		return;
+
+	destroy_hist_field(field_var->var, 0);
+	destroy_hist_field(field_var->val, 0);
+
+	kfree(field_var);
+}
+
+static void destroy_field_vars(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_field_vars; i++)
+		destroy_field_var(hist_data->field_vars[i]);
+}
+
+static void save_field_var(struct hist_trigger_data *hist_data,
+			   struct field_var *field_var)
+{
+	hist_data->field_vars[hist_data->n_field_vars++] = field_var;
+
+	if (field_var->val->flags & HIST_FIELD_FL_STRING)
+		hist_data->n_field_var_str++;
+}
+
+static void destroy_synth_var_refs(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_synth_var_refs; i++)
+		destroy_hist_field(hist_data->synth_var_refs[i], 0);
+}
+
+static void save_synth_var_ref(struct hist_trigger_data *hist_data,
+			 struct hist_field *var_ref)
+{
+	hist_data->synth_var_refs[hist_data->n_synth_var_refs++] = var_ref;
+
+	hist_data->var_refs[hist_data->n_var_refs] = var_ref;
+	var_ref->var_ref_idx = hist_data->n_var_refs++;
+}
+
+static int check_synth_field(struct synth_event *event,
+			     struct hist_field *hist_field,
+			     unsigned int field_pos)
+{
+	struct synth_field *field;
+
+	if (field_pos >= event->n_fields)
+		return -EINVAL;
+
+	field = event->fields[field_pos];
+
+	if (strcmp(field->type, hist_field->type) != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int parse_action_params(char *params, struct action_data *data)
+{
+	char *param, *saved_param;
+	int ret = 0;
+
+	while (params) {
+		if (data->n_params >= SYNTH_FIELDS_MAX)
+			goto out;
+
+		param = strsep(&params, ",");
+		if (!param)
+			goto out;
+
+		param = strstrip(param);
+		if (strlen(param) < 2) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		saved_param = kstrdup(param, GFP_KERNEL);
+		if (!saved_param) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		data->params[data->n_params++] = saved_param;
+	}
+ out:
+	return ret;
+}
+
+static struct hist_field *
+onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
+		 char *system, char *event, char *var)
+{
+	struct hist_field *hist_field;
+
+	var++; /* skip '$' */
+
+	hist_field = find_target_event_var(hist_data, system, event, var);
+	if (!hist_field) {
+		if (!system) {
+			system = data->match_event_system;
+			event = data->match_event;
+		}
+
+		hist_field = find_event_var(system, event, var);
+	}
+
+	return hist_field;
+}
+
+static struct hist_field *
+onmatch_create_field_var(struct hist_trigger_data *hist_data,
+			 struct action_data *data, char *system,
+			 char *event, char *var)
+{
+	struct hist_field *hist_field = NULL;
+	struct field_var *field_var;
+
+	field_var = create_target_field_var(hist_data, system, event, var);
+	if (IS_ERR(field_var))
+		goto out;
+
+	if (field_var) {
+		save_field_var(hist_data, field_var);
+		hist_field = field_var->var;
+	} else {
+		if (!system) {
+			system = data->match_event_system;
+			event = data->match_event;
+		}
+
+		hist_field = create_field_var_hist(hist_data, system, event, var);
+		if (IS_ERR(hist_field))
+			goto free;
+	}
+ out:
+	return hist_field;
+ free:
+	destroy_field_var(field_var);
+	hist_field = NULL;
+	goto out;
+}
+
+static int onmatch_create(struct hist_trigger_data *hist_data,
+			  struct trace_event_file *file,
+			  struct action_data *data)
+{
+	char *event_name, *param, *system = NULL;
+	struct hist_field *hist_field, *var_ref;
+	unsigned int i, var_ref_idx;
+	unsigned int field_pos = 0;
+	struct synth_event *event;
+	int ret = 0;
+
+	mutex_lock(&synth_event_mutex);
+
+	event = find_synth_event(data->synth_event_name);
+	if (!event) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	var_ref_idx = hist_data->n_var_refs;
+
+	for (i = 0; i < data->n_params; i++) {
+		char *p;
+
+		p = param = kstrdup(data->params[i], GFP_KERNEL);
+		if (!param)
+			goto out;
+
+		system = strsep(&param, ".");
+		if (!param) {
+			param = (char *)system;
+			system = event_name = NULL;
+		} else {
+			event_name = strsep(&param, ".");
+			if (!param) {
+				kfree(p);
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+
+		if (param[0] == '$')
+			hist_field = onmatch_find_var(hist_data, data, system,
+						      event_name, param);
+		else
+			hist_field = onmatch_create_field_var(hist_data, data,
+							      system,
+							      event_name,
+							      param);
+
+		if (!hist_field) {
+			kfree(p);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (check_synth_field(event, hist_field, field_pos) == 0) {
+			var_ref = create_var_ref(hist_field);
+			if (!var_ref) {
+				kfree(p);
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			save_synth_var_ref(hist_data, var_ref);
+			field_pos++;
+			kfree(p);
+			continue;
+		}
+
+		kfree(p);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (field_pos != event->n_fields) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	data->fn = action_trace;
+	data->synth_event = event;
+	data->var_ref_idx = var_ref_idx;
+	hist_data->actions[hist_data->n_actions++] = data;
+	save_hist_actions(hist_data);
+ out:
+	mutex_unlock(&synth_event_mutex);
+
+	return ret;
+}
+
+static struct action_data *onmatch_parse(char *str)
+{
+	char *match_event, *match_event_system;
+	char *synth_event_name, *params;
+	struct action_data *data;
+	int ret = -EINVAL;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	match_event = strsep(&str, ")");
+	if (!match_event || !str)
+		goto free;
+
+	match_event_system = strsep(&match_event, ".");
+	if (!match_event)
+		goto free;
+
+	if (IS_ERR(event_file(match_event_system, match_event)))
+		goto free;
+
+	data->match_event = kstrdup(match_event, GFP_KERNEL);
+	data->match_event_system = kstrdup(match_event_system, GFP_KERNEL);
+
+	strsep(&str, ".");
+	if (!str)
+		goto free;
+
+	synth_event_name = strsep(&str, "(");
+	if (!synth_event_name || !str)
+		goto free;
+	data->synth_event_name = kstrdup(synth_event_name, GFP_KERNEL);
+
+	params = strsep(&str, ")");
+	if (!params || !str || (str && strlen(str)))
+		goto free;
+
+	ret = parse_action_params(params, data);
+	if (ret)
+		goto free;
+
+	if (!data->match_event_system || !data->match_event ||
+	    !data->synth_event_name) {
+		ret = -ENOMEM;
+		goto free;
+	}
+ out:
+	return data;
+ free:
+	onmatch_destroy(data);
+	data = ERR_PTR(ret);
+	goto out;
+}
+
 static int create_hitcount_val(struct hist_trigger_data *hist_data)
 {
 	hist_data->fields[HITCOUNT_IDX] =
@@ -2465,19 +3311,37 @@ static void destroy_actions(struct hist_trigger_data *hist_data)
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
 
-		kfree(data);
+		if (data->fn == action_trace)
+			onmatch_destroy(data);
+		else
+			kfree(data);
 	}
 }
 
 static int create_actions(struct hist_trigger_data *hist_data,
 			  struct trace_event_file *file)
 {
+	struct action_data *data;
 	unsigned int i;
 	int ret = 0;
 	char *str;
 
 	for (i = 0; i < hist_data->attrs->n_actions; i++) {
 		str = hist_data->attrs->action_str[i];
+
+		if (strncmp(str, "onmatch(", strlen("onmatch(")) == 0) {
+			char *action_str = str + strlen("onmatch(");
+
+			data = onmatch_parse(action_str);
+			if (IS_ERR(data))
+				return PTR_ERR(data);
+
+			ret = onmatch_create(hist_data, file, data);
+			if (ret) {
+				onmatch_destroy(data);
+				return ret;
+			}
+		}
 	}
 
 	return ret;
@@ -2494,6 +3358,26 @@ static void print_actions(struct seq_file *m,
 	}
 }
 
+static void print_onmatch_spec(struct seq_file *m,
+			       struct hist_trigger_data *hist_data,
+			       struct action_data *data)
+{
+	unsigned int i;
+
+	seq_printf(m, ":onmatch(%s.%s).", data->match_event_system,
+		   data->match_event);
+
+	seq_printf(m, "%s(", data->synth_event->name);
+
+	for (i = 0; i < data->n_params; i++) {
+		if (i)
+			seq_puts(m, ",");
+		seq_printf(m, "%s", data->params[i]);
+	}
+
+	seq_puts(m, ")");
+}
+
 static void print_actions_spec(struct seq_file *m,
 			       struct hist_trigger_data *hist_data)
 {
@@ -2501,6 +3385,19 @@ static void print_actions_spec(struct seq_file *m,
 
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == action_trace)
+			print_onmatch_spec(m, hist_data, data);
+	}
+}
+
+static void destroy_field_var_hists(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_field_var_hists; i++) {
+		kfree(hist_data->field_var_hists[i]->cmd);
+		kfree(hist_data->field_var_hists[i]);
 	}
 }
 
@@ -2514,6 +3411,9 @@ static void destroy_hist_data(struct hist_trigger_data *hist_data)
 	tracing_map_destroy(hist_data->map);
 
 	destroy_actions(hist_data);
+	destroy_field_vars(hist_data);
+	destroy_field_var_hists(hist_data);
+	destroy_synth_var_refs(hist_data);
 
 	kfree(hist_data);
 }
@@ -2648,6 +3548,8 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 			tracing_map_set_var(elt, var_idx, hist_val);
 		}
 	}
+
+	update_field_vars(hist_data, elt, rbe, rec);
 }
 
 static inline void add_to_key(char *compound_key, void *key,
@@ -2861,6 +3763,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 		}
 	}
 
+	print_actions(m, hist_data, elt);
+
 	seq_puts(m, "\n");
 }
 
@@ -3128,6 +4032,8 @@ static void event_hist_trigger_free(struct event_trigger_ops *ops,
 
 		remove_hist_vars(hist_data);
 
+		remove_hist_actions(hist_data);
+
 		destroy_hist_data(hist_data);
 	}
 }
@@ -3390,6 +4296,21 @@ static bool hist_trigger_check_refs(struct event_trigger_data *data,
 	return false;
 }
 
+static void unregister_field_var_hists(struct hist_trigger_data *hist_data)
+{
+	struct trace_event_file *file;
+	unsigned int i;
+	char *cmd;
+	int ret;
+
+	for (i = 0; i < hist_data->n_field_var_hists; i++) {
+		file = hist_data->field_var_hists[i]->hist_data->event_file;
+		cmd = hist_data->field_var_hists[i]->cmd;
+		ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+					      "!hist", "hist", cmd);
+	}
+}
+
 static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
 				    struct event_trigger_data *data,
 				    struct trace_event_file *file)
@@ -3405,6 +4326,7 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
 		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
 			if (!hist_trigger_match(data, test, named_data, false))
 				continue;
+			unregister_field_var_hists(test->private_data);
 			unregistered = true;
 			list_del_rcu(&test->list);
 			trace_event_trigger_enable_disable(file, 0);
@@ -3448,6 +4370,7 @@ static void hist_unreg_all(struct trace_event_file *file)
 
 	list_for_each_entry_safe(test, n, &file->triggers, list) {
 		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			unregister_field_var_hists(test->private_data);
 			list_del_rcu(&test->list);
 			trace_event_trigger_enable_disable(file, 0);
 			update_cond_flag(file);
@@ -3571,6 +4494,8 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 
 	remove_hist_vars(hist_data);
 
+	remove_hist_actions(hist_data);
+
 	kfree(trigger_data);
 	destroy_hist_data(hist_data);
 
-- 
1.9.3

[toc] | [prev] | [next] | [standalone]

#1675179 — [PATCH 14/32] tracing: Add hist_data member to hist_field

Allow hist_data access via hist_field.  Some users of hist_fields
require or will require more access to the associated hist_data.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index aeae3b4..fb08a75 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -39,6 +39,7 @@ struct hist_field {
 	unsigned int			offset;
 	unsigned int                    is_signed;
 	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];
+	struct hist_trigger_data	*hist_data;
 };
 
 static u64 hist_field_none(struct hist_field *field, void *event,
@@ -415,7 +416,8 @@ static void destroy_hist_field(struct hist_field *hist_field,
 	kfree(hist_field);
 }
 
-static struct hist_field *create_hist_field(struct ftrace_event_field *field,
+static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
+					    struct ftrace_event_field *field,
 					    unsigned long flags)
 {
 	struct hist_field *hist_field;
@@ -427,6 +429,8 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	if (!hist_field)
 		return NULL;
 
+	hist_field->hist_data = hist_data;
+
 	if (flags & HIST_FIELD_FL_HITCOUNT) {
 		hist_field->fn = hist_field_counter;
 		goto out;
@@ -440,7 +444,7 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	if (flags & HIST_FIELD_FL_LOG2) {
 		unsigned long fl = flags & ~HIST_FIELD_FL_LOG2;
 		hist_field->fn = hist_field_log2;
-		hist_field->operands[0] = create_hist_field(field, fl);
+		hist_field->operands[0] = create_hist_field(hist_data, field, fl);
 		hist_field->size = hist_field->operands[0]->size;
 		goto out;
 	}
@@ -493,7 +497,7 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data)
 static int create_hitcount_val(struct hist_trigger_data *hist_data)
 {
 	hist_data->fields[HITCOUNT_IDX] =
-		create_hist_field(NULL, HIST_FIELD_FL_HITCOUNT);
+		create_hist_field(hist_data, NULL, HIST_FIELD_FL_HITCOUNT);
 	if (!hist_data->fields[HITCOUNT_IDX])
 		return -ENOMEM;
 
@@ -539,7 +543,7 @@ static int create_val_field(struct hist_trigger_data *hist_data,
 		}
 	}
 
-	hist_data->fields[val_idx] = create_hist_field(field, flags);
+	hist_data->fields[val_idx] = create_hist_field(hist_data, field, flags);
 	if (!hist_data->fields[val_idx]) {
 		ret = -ENOMEM;
 		goto out;
@@ -649,7 +653,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 		}
 	}
 
-	hist_data->fields[key_idx] = create_hist_field(field, flags);
+	hist_data->fields[key_idx] = create_hist_field(hist_data, field, flags);
 	if (!hist_data->fields[key_idx]) {
 		ret = -ENOMEM;
 		goto out;
-- 
1.9.3

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#1675180 — [PATCH 26/32] tracing: Make duplicate count from tracing_map available

Though extremely rare, there can be duplicate entries in the tracing
map.  This isn't normally a problem, as the sorting code makes this
transparent by merging them during the sort.

It's useful to know however, as a check on that assumption - if a
non-zero duplicate count is seen more than rarely, it might indicate
an unexpected change to the algorithm, or a pathological data set.

Add an extra param to tracing_map_sort_entries() and use it to display
the value in the hist trigger output.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 14 ++++++++------
 kernel/trace/tracing_map.c       | 12 +++++++++---
 kernel/trace/tracing_map.h       |  3 ++-
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 53a0634..ab94e2a 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4011,7 +4011,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 }
 
 static int print_entries(struct seq_file *m,
-			 struct hist_trigger_data *hist_data)
+			 struct hist_trigger_data *hist_data,
+			 unsigned int *n_dups)
 {
 	struct tracing_map_sort_entry **sort_entries = NULL;
 	struct tracing_map *map = hist_data->map;
@@ -4019,7 +4020,7 @@ static int print_entries(struct seq_file *m,
 
 	n_entries = tracing_map_sort_entries(map, hist_data->sort_keys,
 					     hist_data->n_sort_keys,
-					     &sort_entries);
+					     &sort_entries, n_dups);
 	if (n_entries < 0)
 		return n_entries;
 
@@ -4038,6 +4039,7 @@ static void hist_trigger_show(struct seq_file *m,
 {
 	struct hist_trigger_data *hist_data;
 	int n_entries, ret = 0;
+	unsigned int n_dups;
 
 	if (n > 0)
 		seq_puts(m, "\n\n");
@@ -4047,15 +4049,15 @@ static void hist_trigger_show(struct seq_file *m,
 	seq_puts(m, "#\n\n");
 
 	hist_data = data->private_data;
-	n_entries = print_entries(m, hist_data);
+	n_entries = print_entries(m, hist_data, &n_dups);
 	if (n_entries < 0) {
 		ret = n_entries;
 		n_entries = 0;
 	}
 
-	seq_printf(m, "\nTotals:\n    Hits: %llu\n    Entries: %u\n    Dropped: %llu\n",
-		   (u64)atomic64_read(&hist_data->map->hits),
-		   n_entries, (u64)atomic64_read(&hist_data->map->drops));
+	seq_printf(m, "\nTotals:\n    Hits: %llu\n    Entries: %u\n    Dropped: %llu\n    Duplicates: %u\n",
+		   (u64)atomic64_read(&hist_data->map->hits), n_entries,
+		   (u64)atomic64_read(&hist_data->map->drops), n_dups);
 }
 
 static int hist_show(struct seq_file *m, void *v)
diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index f987069..9ed04b6 100644
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -1084,6 +1084,7 @@ static void sort_secondary(struct tracing_map *map,
  * @map: The tracing_map
  * @sort_key: The sort key to use for sorting
  * @sort_entries: outval: pointer to allocated and sorted array of entries
+ * @n_dups: outval: pointer to variable receiving a count of duplicates found
  *
  * tracing_map_sort_entries() sorts the current set of entries in the
  * map and returns the list of tracing_map_sort_entries containing
@@ -1100,13 +1101,16 @@ static void sort_secondary(struct tracing_map *map,
  * The client should not hold on to the returned array but should use
  * it and call tracing_map_destroy_sort_entries() when done.
  *
- * Return: the number of sort_entries in the struct tracing_map_sort_entry
- * array, negative on error
+ * Return: the number of sort_entries in the struct
+ * tracing_map_sort_entry array, negative on error.  If n_dups is
+ * non-NULL, it will receive the number of duplicate entries found
+ * (and merged) during the sort.
  */
 int tracing_map_sort_entries(struct tracing_map *map,
 			     struct tracing_map_sort_key *sort_keys,
 			     unsigned int n_sort_keys,
-			     struct tracing_map_sort_entry ***sort_entries)
+			     struct tracing_map_sort_entry ***sort_entries,
+			     unsigned int *n_dups)
 {
 	int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
 			      const struct tracing_map_sort_entry **);
@@ -1147,6 +1151,8 @@ int tracing_map_sort_entries(struct tracing_map *map,
 	if (ret < 0)
 		goto free;
 	n_entries -= ret;
+	if (n_dups)
+		*n_dups = ret;
 
 	if (is_key(map, sort_keys[0].field_idx))
 		cmp_entries_fn = cmp_entries_key;
diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h
index 303bc4f..a44cc0c 100644
--- a/kernel/trace/tracing_map.h
+++ b/kernel/trace/tracing_map.h
@@ -286,7 +286,8 @@ extern void tracing_map_set_field_descr(struct tracing_map *map,
 tracing_map_sort_entries(struct tracing_map *map,
 			 struct tracing_map_sort_key *sort_keys,
 			 unsigned int n_sort_keys,
-			 struct tracing_map_sort_entry ***sort_entries);
+			 struct tracing_map_sort_entry ***sort_entries,
+			 unsigned int *n_dups);
 
 extern void
 tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
-- 
1.9.3

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#1675181 — [PATCH 01/32] tracing: Add hist_field_name() accessor

In preparation for hist_fields that won't be strictly based on
trace_event_fields, add a new hist_field_name() accessor to allow that
flexibility and update associated users.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 68 +++++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 22 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1c21d0e..91ffc39 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -146,6 +146,23 @@ struct hist_trigger_data {
 	struct tracing_map		*map;
 };
 
+static const char *hist_field_name(struct hist_field *field,
+				   unsigned int level)
+{
+	const char *field_name = "";
+
+	if (level > 1)
+		return field_name;
+
+	if (field->field)
+		field_name = field->field->name;
+
+	if (field_name == NULL)
+		field_name = "";
+
+	return field_name;
+}
+
 static hist_field_fn_t select_value_fn(int field_size, int field_is_signed)
 {
 	hist_field_fn_t fn = NULL;
@@ -653,7 +670,6 @@ static int is_descending(const char *str)
 static int create_sort_keys(struct hist_trigger_data *hist_data)
 {
 	char *fields_str = hist_data->attrs->sort_key_str;
-	struct ftrace_event_field *field = NULL;
 	struct tracing_map_sort_key *sort_key;
 	int descending, ret = 0;
 	unsigned int i, j;
@@ -670,7 +686,9 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 	}
 
 	for (i = 0; i < TRACING_MAP_SORT_KEYS_MAX; i++) {
+		struct hist_field *hist_field;
 		char *field_str, *field_name;
+		const char *test_name;
 
 		sort_key = &hist_data->sort_keys[i];
 
@@ -703,8 +721,11 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 		}
 
 		for (j = 1; j < hist_data->n_fields; j++) {
-			field = hist_data->fields[j]->field;
-			if (field && (strcmp(field_name, field->name) == 0)) {
+			hist_field = hist_data->fields[j];
+			test_name = hist_field_name(hist_field, 0);
+			if (test_name == NULL)
+				continue;
+			if (strcmp(field_name, test_name) == 0) {
 				sort_key->field_idx = j;
 				descending = is_descending(field_str);
 				if (descending < 0) {
@@ -952,6 +973,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 	struct hist_field *key_field;
 	char str[KSYM_SYMBOL_LEN];
 	bool multiline = false;
+	const char *field_name;
 	unsigned int i;
 	u64 uval;
 
@@ -963,26 +985,27 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 		if (i > hist_data->n_vals)
 			seq_puts(m, ", ");
 
+		field_name = hist_field_name(key_field, 0);
+
 		if (key_field->flags & HIST_FIELD_FL_HEX) {
 			uval = *(u64 *)(key + key_field->offset);
-			seq_printf(m, "%s: %llx",
-				   key_field->field->name, uval);
+			seq_printf(m, "%s: %llx", field_name, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_SYM) {
 			uval = *(u64 *)(key + key_field->offset);
 			sprint_symbol_no_offset(str, uval);
-			seq_printf(m, "%s: [%llx] %-45s",
-				   key_field->field->name, uval, str);
+			seq_printf(m, "%s: [%llx] %-45s", field_name,
+				   uval, str);
 		} else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) {
 			uval = *(u64 *)(key + key_field->offset);
 			sprint_symbol(str, uval);
-			seq_printf(m, "%s: [%llx] %-55s",
-				   key_field->field->name, uval, str);
+			seq_printf(m, "%s: [%llx] %-55s", field_name,
+				   uval, str);
 		} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
 			char *comm = elt->private_data;
 
 			uval = *(u64 *)(key + key_field->offset);
-			seq_printf(m, "%s: %-16s[%10llu]",
-				   key_field->field->name, comm, uval);
+			seq_printf(m, "%s: %-16s[%10llu]", field_name,
+				   comm, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_SYSCALL) {
 			const char *syscall_name;
 
@@ -991,8 +1014,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 			if (!syscall_name)
 				syscall_name = "unknown_syscall";
 
-			seq_printf(m, "%s: %-30s[%3llu]",
-				   key_field->field->name, syscall_name, uval);
+			seq_printf(m, "%s: %-30s[%3llu]", field_name,
+				   syscall_name, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
 			seq_puts(m, "stacktrace:\n");
 			hist_trigger_stacktrace_print(m,
@@ -1000,15 +1023,14 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 						      HIST_STACKTRACE_DEPTH);
 			multiline = true;
 		} else if (key_field->flags & HIST_FIELD_FL_LOG2) {
-			seq_printf(m, "%s: ~ 2^%-2llu", key_field->field->name,
+			seq_printf(m, "%s: ~ 2^%-2llu", field_name,
 				   *(u64 *)(key + key_field->offset));
 		} else if (key_field->flags & HIST_FIELD_FL_STRING) {
-			seq_printf(m, "%s: %-50s", key_field->field->name,
+			seq_printf(m, "%s: %-50s", field_name,
 				   (char *)(key + key_field->offset));
 		} else {
 			uval = *(u64 *)(key + key_field->offset);
-			seq_printf(m, "%s: %10llu", key_field->field->name,
-				   uval);
+			seq_printf(m, "%s: %10llu", field_name, uval);
 		}
 	}
 
@@ -1021,13 +1043,13 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
 		   tracing_map_read_sum(elt, HITCOUNT_IDX));
 
 	for (i = 1; i < hist_data->n_vals; i++) {
+		field_name = hist_field_name(hist_data->fields[i], 0);
+
 		if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {
-			seq_printf(m, "  %s: %10llx",
-				   hist_data->fields[i]->field->name,
+			seq_printf(m, "  %s: %10llx", field_name,
 				   tracing_map_read_sum(elt, i));
 		} else {
-			seq_printf(m, "  %s: %10llu",
-				   hist_data->fields[i]->field->name,
+			seq_printf(m, "  %s: %10llu", field_name,
 				   tracing_map_read_sum(elt, i));
 		}
 	}
@@ -1142,7 +1164,9 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 
 static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 {
-	seq_printf(m, "%s", hist_field->field->name);
+	const char *field_name = hist_field_name(hist_field, 0);
+
+	seq_printf(m, "%s", field_name);
 	if (hist_field->flags) {
 		const char *flags_str = get_hist_field_flags(hist_field);
 
-- 
1.9.3

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#1675182 — [PATCH 27/32] tracing: Add cpu field for hist triggers

A common key to use in a histogram is the cpuid - add a new cpu
'synthetic' field for that purpose.  This field is named cpu rather
than $cpu or $common_cpu because 'cpu' already exists as a special
filter field and it makes more sense to match that rather than add
another name for the same thing.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 Documentation/trace/events.txt   | 18 ++++++++++++++++++
 kernel/trace/trace_events_hist.c | 30 +++++++++++++++++++++++++++---
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 2cc08d4..9717688 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -668,6 +668,24 @@ The following commands are supported:
   The examples below provide a more concrete illustration of the
   concepts and typical usage patterns discussed above.
 
+  'synthetic' event fields
+  ------------------------
+
+  There are a number of 'synthetic fields' available for use as keys
+  or values in a hist trigger.  These look like and behave as if they
+  were event fields, but aren't actually part of the event's field
+  definition or format file.  They are however available for any
+  event, and can be used anywhere an actual event field could be.
+  'Synthetic' field names are always prefixed with a '$' character to
+  indicate that they're not normal fields (with the exception of
+  'cpu', for compatibility with existing filter usage):
+
+    $common_timestamp      u64 - timestamp (from ring buffer) associated
+                                 with the event, in nanoseconds.  May be
+				 modified by .usecs to have timestamps
+				 interpreted as microseconds.
+    cpu                    int - the cpu on which the event occurred.
+
 
 6.2 'hist' trigger examples
 ---------------------------
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index ab94e2a..904a635 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -224,6 +224,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_VAR_ONLY		= 8192,
 	HIST_FIELD_FL_EXPR		= 16384,
 	HIST_FIELD_FL_VAR_REF		= 32768,
+	HIST_FIELD_FL_CPU		= 65536,
 };
 
 struct hist_trigger_attrs {
@@ -1081,6 +1082,16 @@ static u64 hist_field_timestamp(struct hist_field *hist_field,
 	return ts;
 }
 
+static u64 hist_field_cpu(struct hist_field *hist_field,
+			  struct tracing_map_elt *elt,
+			  struct ring_buffer_event *rbe,
+			  void *event)
+{
+	int cpu = raw_smp_processor_id();
+
+	return cpu;
+}
+
 static struct hist_field *check_var_ref(struct hist_field *hist_field,
 					struct hist_trigger_data *var_data,
 					unsigned int var_idx)
@@ -1407,6 +1418,8 @@ static const char *hist_field_name(struct hist_field *field,
 		field_name = hist_field_name(field->operands[0], ++level);
 	else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
 		field_name = "$common_timestamp";
+	else if (field->flags & HIST_FIELD_FL_CPU)
+		field_name = "cpu";
 	else if (field->flags & HIST_FIELD_FL_EXPR ||
 		 field->flags & HIST_FIELD_FL_VAR_REF)
 		field_name = field->name;
@@ -1848,6 +1861,15 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		goto out;
 	}
 
+	if (flags & HIST_FIELD_FL_CPU) {
+		hist_field->fn = hist_field_cpu;
+		hist_field->size = sizeof(int);
+		hist_field->type = kstrdup("int", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+		goto out;
+	}
+
 	if (WARN_ON_ONCE(!field))
 		goto out;
 
@@ -1980,7 +2002,9 @@ static struct hist_field *parse_var_ref(char *system, char *event_name,
 		hist_data->enable_timestamps = true;
 		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
 			hist_data->attrs->ts_in_usecs = true;
-	} else {
+	} else if (strcmp(field_name, "cpu") == 0)
+		*flags |= HIST_FIELD_FL_CPU;
+	else {
 		field = trace_find_event_field(file->event_call, field_name);
 		if (!field)
 			return ERR_PTR(-EINVAL);
@@ -3019,7 +3043,6 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 				goto out;
 			}
 		}
-
 		if (param[0] == '$')
 			hist_field = onmatch_find_var(hist_data, data, system,
 						      event_name, param);
@@ -3034,7 +3057,6 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 			ret = -EINVAL;
 			goto out;
 		}
-
 		if (check_synth_field(event, hist_field, field_pos) == 0) {
 			var_ref = create_var_ref(hist_field);
 			if (!var_ref) {
@@ -4128,6 +4150,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 
 	if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
 		seq_puts(m, "$common_timestamp");
+	else if (hist_field->flags & HIST_FIELD_FL_CPU)
+		seq_puts(m, "cpu");
 	else if (field_name)
 		seq_printf(m, "%s", field_name);
 
-- 
1.9.3

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#1675870

On Mon, 26 Jun 2017 17:49:00 -0500
Tom Zanussi <tom.zanussi@linux.intel.com> wrote:

> This patchset adds support for 'inter-event' quantities to the trace
> event subsystem.  The most important example of inter-event quantities
> are latencies, or the time differences between two events.
>

Hi Tom,

Thanks for sending this out. I'm going to try to find some time this
week to take a look at it. It's quite a lot to go over. I don't think
it will be ready for this merge window, as I don't like rushing things
like this, and we are already at rc7. But I want to get this in by 4.14.

-- Steve

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#1676710

Hi Tom,

On Mon, 26 Jun 2017 17:49:01 -0500
Tom Zanussi <tom.zanussi@linux.intel.com> wrote:

> This patchset adds support for 'inter-event' quantities to the trace
> event subsystem.  The most important example of inter-event quantities
> are latencies, or the time differences between two events.
> 

Thank you for your great work!
I'm playing this and found some issues.

(1) new event format
----
# echo "wakeup_latency u64 lat; pid_t pid; int prio" > synthetic_events 
# cat /sys/kernel/debug/tracing # cat events/synthetic/wakeup_latency/format 
name: wakeup_latency
ID: 972
format:
	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
	field:unsigned char common_preempt_count;	offset:3;	size:1;signed:0;
	field:int common_pid;	offset:4;	size:4;	signed:1;

	field:u64 lat;	offset:16;	size:8;	signed:0;
	field:pid_t pid;	offset:24;	size:4;	signed:1;
	field:int prio;	offset:32;	size:4;	signed:1;

print fmt: "lat: 0x%08lx, pid: 0x%08lx, prio: 0x%08lx", ((u64)(REC->lat)), ((u64)(REC->pid)), ((u64)(REC->prio))
----
Here, IMO, this format would be better "lat=0x%08lx pid=0x%08lx prio=0x%08lx" so that perf-script can parse it correctly.

(2) lockdep found a dead lock case
When I added a histogram trigger, it happened.
----
# echo 'hist:keys=pid:ts0=$common_timestamp.usecs' >>  /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
[33967.672485] 
[33967.673117] ======================================================
[33967.673117] WARNING: possible circular locking dependency detected
[33967.673117] 4.12.0-rc5+ #1 Not tainted
[33967.673117] ------------------------------------------------------
[33967.673117] bash/708 is trying to acquire lock:
[33967.673117]  (trace_types_lock){+.+.+.}, at: [<ffffffff811307e6>] tracing_set_clock+0x66/0xe0
[33967.673117] 
[33967.673117] but task is already holding lock:
[33967.673117]  (trigger_cmd_mutex){+.+.+.}, at: [<ffffffff81144264>] event_trigger_write+0xb4/0x1a0
[33967.673117] 
[33967.673117] which lock already depends on the new lock.
[33967.673117] 
[33967.673117] 
[33967.673117] the existing dependency chain (in reverse order) is:
[33967.673117] 
[33967.673117] -> #2 (trigger_cmd_mutex){+.+.+.}:
[33967.673117]        lock_acquire+0xe3/0x1d0
[33967.673117]        __mutex_lock+0x81/0x950
[33967.673117]        mutex_lock_nested+0x1b/0x20
[33967.673117]        event_trigger_write+0xb4/0x1a0
[33967.673117]        __vfs_write+0x28/0x120
[33967.673117]        vfs_write+0xc7/0x1b0
[33967.673117]        SyS_write+0x49/0xa0
[33967.673117]        entry_SYSCALL_64_fastpath+0x1f/0xbe
[33967.673117] 
[33967.673117] -> #1 (event_mutex){+.+.+.}:
[33967.673117]        lock_acquire+0xe3/0x1d0
[33967.673117]        __mutex_lock+0x81/0x950
[33967.673117]        mutex_lock_nested+0x1b/0x20
[33967.673117]        trace_add_event_call+0x28/0xc0
[33967.673117]        create_synth_event+0x40a/0x880
[33967.673117]        trace_run_command+0x54/0x60
[33967.673117]        trace_parse_run_command+0xc4/0x160
[33967.673117]        synth_events_write+0x10/0x20
[33967.673117]        __vfs_write+0x28/0x120
[33967.673117]        vfs_write+0xc7/0x1b0
[33967.673117]        SyS_write+0x49/0xa0
[33967.673117]        entry_SYSCALL_64_fastpath+0x1f/0xbe
[33967.673117] 
[33967.673117] -> #0 (trace_types_lock){+.+.+.}:
[33967.673117]        __lock_acquire+0x1026/0x11d0
[33967.673117]        lock_acquire+0xe3/0x1d0
[33967.673117]        __mutex_lock+0x81/0x950
[33967.673117]        mutex_lock_nested+0x1b/0x20
[33967.673117]        tracing_set_clock+0x66/0xe0
[33967.673117]        hist_register_trigger+0x209/0x2a0
[33967.673117]        event_hist_trigger_func+0xc6b/0x2610
[33967.673117]        event_trigger_write+0xfa/0x1a0
[33967.673117]        __vfs_write+0x28/0x120
[33967.673117]        vfs_write+0xc7/0x1b0
[33967.673117]        SyS_write+0x49/0xa0
[33967.673117]        entry_SYSCALL_64_fastpath+0x1f/0xbe
[33967.673117] 
[33967.673117] other info that might help us debug this:
[33967.673117] 
[33967.673117] Chain exists of:
[33967.673117]   trace_types_lock --> event_mutex --> trigger_cmd_mutex
[33967.673117] 
[33967.673117]  Possible unsafe locking scenario:
[33967.673117] 
[33967.673117]        CPU0                    CPU1
[33967.673117]        ----                    ----
[33967.673117]   lock(trigger_cmd_mutex);
[33967.673117]                                lock(event_mutex);
[33967.673117]                                lock(trigger_cmd_mutex);
[33967.673117]   lock(trace_types_lock);
[33967.673117] 
[33967.673117]  *** DEADLOCK ***
[33967.673117] 
[33967.673117] 3 locks held by bash/708:
[33967.673117]  #0:  (sb_writers#8){.+.+.+}, at: [<ffffffff811ef42f>] vfs_write+0x18f/0x1b0
[33967.673117]  #1:  (event_mutex){+.+.+.}, at: [<ffffffff8114421c>] event_trigger_write+0x6c/0x1a0
[33967.673117]  #2:  (trigger_cmd_mutex){+.+.+.}, at: [<ffffffff81144264>] event_trigger_write+0xb4/0x1a0
[33967.673117] 
[33967.673117] stack backtrace:
[33967.673117] CPU: 4 PID: 708 Comm: bash Not tainted 4.12.0-rc5+ #1
[33967.673117] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.fc25 04/01/2014
[33967.673117] Call Trace:
[33967.673117]  dump_stack+0x86/0xcf
[33967.673117]  print_circular_bug+0x1be/0x210
[33967.673117]  __lock_acquire+0x1026/0x11d0
[33967.673117]  lock_acquire+0xe3/0x1d0
[33967.673117]  ? lock_acquire+0xe3/0x1d0
[33967.673117]  ? tracing_set_clock+0x66/0xe0
[33967.673117]  ? tracing_set_clock+0x66/0xe0
[33967.673117]  __mutex_lock+0x81/0x950
[33967.673117]  ? tracing_set_clock+0x66/0xe0
[33967.673117]  ? rcu_read_lock_sched_held+0x4a/0x80
[33967.673117]  ? tracing_set_clock+0x66/0xe0
[33967.673117]  mutex_lock_nested+0x1b/0x20
[33967.673117]  ? mutex_lock_nested+0x1b/0x20
[33967.673117]  tracing_set_clock+0x66/0xe0
[33967.673117]  hist_register_trigger+0x209/0x2a0
[33967.673117]  event_hist_trigger_func+0xc6b/0x2610
[33967.673117]  ? event_trigger_write+0xb4/0x1a0
[33967.673117]  ? __mutex_lock+0x81/0x950
[33967.673117]  ? event_trigger_write+0xb4/0x1a0
[33967.673117]  ? event_trigger_write+0xb4/0x1a0
[33967.673117]  event_trigger_write+0xfa/0x1a0
[33967.673117]  __vfs_write+0x28/0x120
[33967.673117]  ? rcu_read_lock_sched_held+0x4a/0x80
[33967.673117]  ? rcu_sync_lockdep_assert+0x2f/0x60
[33967.673117]  ? __sb_start_write+0xe7/0x1e0
[33967.673117]  ? vfs_write+0x18f/0x1b0
[33967.673117]  vfs_write+0xc7/0x1b0
[33967.673117]  SyS_write+0x49/0xa0
[33967.673117]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[33967.673117] RIP: 0033:0x4bb040
[33967.673117] RSP: 002b:00007ffd79e44288 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[33967.673117] RAX: ffffffffffffffda RBX: 0000000002829220 RCX: 00000000004bb040
[33967.673117] RDX: 000000000000002a RSI: 00000000028288f0 RDI: 0000000000000001
[33967.673117] RBP: 0000000002828000 R08: fefefefefefefeff R09: ff8772626471ff72
[33967.673117] R10: 00000000028288f0 R11: 0000000000000246 R12: 0000000002827f90
[33967.673117] R13: 0000000000000003 R14: 0000000000000001 R15: 0000000000000071
----

Anyway I just started to run this series, I'll also try to check other
features.

Thank you!


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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#1677088

Hi Masami,

On Wed, 2017-06-28 at 23:21 +0900, Masami Hiramatsu wrote:
> Hi Tom,
> 
> On Mon, 26 Jun 2017 17:49:01 -0500
> Tom Zanussi <tom.zanussi@linux.intel.com> wrote:
> 
> > This patchset adds support for 'inter-event' quantities to the trace
> > event subsystem.  The most important example of inter-event quantities
> > are latencies, or the time differences between two events.
> > 
> 
> Thank you for your great work!
> I'm playing this and found some issues.
> 
> (1) new event format
> ----
> # echo "wakeup_latency u64 lat; pid_t pid; int prio" > synthetic_events 
> # cat /sys/kernel/debug/tracing # cat events/synthetic/wakeup_latency/format 
> name: wakeup_latency
> ID: 972
> format:
> 	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
> 	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
> 	field:unsigned char common_preempt_count;	offset:3;	size:1;signed:0;
> 	field:int common_pid;	offset:4;	size:4;	signed:1;
> 
> 	field:u64 lat;	offset:16;	size:8;	signed:0;
> 	field:pid_t pid;	offset:24;	size:4;	signed:1;
> 	field:int prio;	offset:32;	size:4;	signed:1;
> 
> print fmt: "lat: 0x%08lx, pid: 0x%08lx, prio: 0x%08lx", ((u64)(REC->lat)), ((u64)(REC->pid)), ((u64)(REC->prio))
> ----
> Here, IMO, this format would be better "lat=0x%08lx pid=0x%08lx prio=0x%08lx" so that perf-script can parse it correctly.
> 

OK, will change it.

> (2) lockdep found a dead lock case
> When I added a histogram trigger, it happened.
> ----
> # echo 'hist:keys=pid:ts0=$common_timestamp.usecs' >>  /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
> [33967.672485] 
> [33967.673117] ======================================================
> [33967.673117] WARNING: possible circular locking dependency detected
> [33967.673117] 4.12.0-rc5+ #1 Not tainted
> [33967.673117] ------------------------------------------------------

Yeah, will fix this and anything else similar, thanks for pointing it
out.

Tom

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#1679275 — Re: [PATCH 00/32] tracing: Inter-event (e.g. latency) support

Hi Tom,
Nice series and nice ELC talk as well. Thanks.

On Mon, Jun 26, 2017 at 3:49 PM, Tom Zanussi
<tom.zanussi@linux.intel.com> wrote:
> This patchset adds support for 'inter-event' quantities to the trace
> event subsystem.  The most important example of inter-event quantities
> are latencies, or the time differences between two events.

I tried your patches out and they are working fine for me. I will test
them out more.

I think for the wakeup latency in your examples, its better / more
accurate to use sched_waking instead of sched_wakeup tracepoint? [1]

Also, one other comment I had is, it would be nice to suppress the
output of individual trace events that are part of the synthetic event
into the trace buffer. Otherwise I feel the value of it is slightly
diminished - because one can simply post-process the individual
non-synthetic trace events themselves to get wake up latencies which
the synthetic events is trying to calculate in the first place.
Inorder to conserve space, if a user doesn't care about individual
events, and just the synthetic events then the individual ones
shouldn't be written to the trace buffer IMO.

-Joel

[1] commit fbd705a0c6184580d0e2fbcbd47a37b6e5822511 (sched: Introduce
the 'trace_sched_waking' tracepoint)

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