linux-kernel - [RFC PATCH v2 04/20] tracing/filters: Enable filtering the CPU common field by a cpumask

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Message-Id: <20230720163056.2564824-5-vschneid@redhat.com>
Date:   Thu, 20 Jul 2023 17:30:40 +0100
From:   Valentin Schneider <vschneid@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, kvm@...r.kernel.org, linux-mm@...ck.org,
        bpf@...r.kernel.org, x86@...nel.org, rcu@...r.kernel.org,
        linux-kselftest@...r.kernel.org
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Subject: [RFC PATCH v2 04/20] tracing/filters: Enable filtering the CPU common field by a cpumask

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 & CPUS{12-52}' \
		   -e 'sched_wakeup' -f 'target_cpu & CPUS{12-52}'

Signed-off-by: Valentin Schneider <vschneid@...hat.com>
---
 kernel/trace/trace_events_filter.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 1e14f801685a8..3009d0c61b532 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_,
@@ -937,6 +938,14 @@ static int filter_pred_cpu(struct filter_pred *pred, void *event)
 	}
 }
 
+/* Filter predicate for current CPU vs user-provided cpumask */
+static int filter_pred_cpu_cpumask(struct filter_pred *pred, void *event)
+{
+	int cpu = raw_smp_processor_id();
+
+	return do_filter_scalar_cpumask(pred->op, cpu, pred->mask);
+}
+
 /* Filter predicate for cpumask field vs user-provided cpumask */
 static int filter_pred_cpumask(struct filter_pred *pred, void *event)
 {
@@ -1440,6 +1449,8 @@ 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:
@@ -1659,6 +1670,7 @@ static int parse_pred(const char *str, void *data,
 
 		switch (field->filter_type) {
 		case FILTER_CPUMASK:
+		case FILTER_CPU:
 		case FILTER_OTHER:
 			break;
 		default:
@@ -1714,6 +1726,8 @@ 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