[RFC PATCH 04/14] tracing/filters: Enable filtering the CPU common field by a cpumask

Valentin Schneider
2023-07-05T18:17:33Z

The tracing_cpumask lets us specify which CPUs are traced in a buffer
instance, but doesn't let us do this on a per-event basis (unless one
creates an instance per event).

A previous commit added filtering scalar fields by a user-given cpumask,
make this work with the CPU common field as well.

This enables doing things like

$ trace-cmd record -e 'sched_switch' -f 'CPU & MASK{12-52}' \
-e 'sched_wakeup' -f 'target_cpu & MASK{12-52}'

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
---
kernel/trace/trace_events_filter.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 99e111c237a93..b3d2612d4670a 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -68,6 +68,7 @@ enum filter_pred_fn {
FILTER_PRED_FN_PCHAR_USER,
FILTER_PRED_FN_PCHAR,
FILTER_PRED_FN_CPU,
+ FILTER_PRED_FN_CPU_CPUMASK,
FILTER_PRED_FN_CPUMASK,
FILTER_PRED_FN_FUNCTION,
FILTER_PRED_FN_,
@@ -933,6 +934,13 @@ static int filter_pred_cpu(struct filter_pred *pred, void *event)
}
}

+static int filter_pred_cpu_cpumask(struct filter_pred *pred, void *event)
+{
+ int cpu = raw_smp_processor_id();
+
+ return do_filter_cpumask_scalar(pred->op, cpu, pred->mask);
+}
+
/* Filter predicate for cpumasks. */
static int filter_pred_cpumask(struct filter_pred *pred, void *event)
{
@@ -1436,6 +1444,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event)
return filter_pred_pchar(pred, event);
case FILTER_PRED_FN_CPU:
return filter_pred_cpu(pred, event);
+ case FILTER_PRED_FN_CPU_CPUMASK:
+ return filter_pred_cpu_cpumask(pred, event);
case FILTER_PRED_FN_CPUMASK:
return filter_pred_cpumask(pred, event);
case FILTER_PRED_FN_FUNCTION:
@@ -1654,6 +1664,7 @@ static int parse_pred(const char *str, void *data,
char *tmp;

if (field->filter_type != FILTER_CPUMASK &&
+ field->filter_type != FILTER_CPU &&
field->filter_type != FILTER_OTHER) {
parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
goto err_free;
@@ -1698,6 +1709,8 @@ static int parse_pred(const char *str, void *data,
i++;
if (field->filter_type == FILTER_CPUMASK) {
pred->fn_num = FILTER_PRED_FN_CPUMASK;
+ } else if (field->filter_type == FILTER_CPU) {
+ pred->fn_num = FILTER_PRED_FN_CPU_CPUMASK;
} else {
switch (field->size) {
case 8:
--
2.31.1