perf kwork: Add softirq trace BPF support

Implements softirq trace bpf function.

Test cases:
Trace softirq latency without filter:

# perf kwork -k softirq lat -b
Starting trace, Hit <Ctrl+C> to stop and report
^C
Kwork Name | Cpu | Avg delay | Count | Max delay | Max delay start | Max delay end |
--------------------------------------------------------------------------------------------------------------------------------
(s)RCU:9 | 0005 | 0.281 ms | 3 | 0.338 ms | 111295.752222 s | 111295.752560 s |
(s)RCU:9 | 0002 | 0.262 ms | 24 | 1.400 ms | 111301.335986 s | 111301.337386 s |
(s)SCHED:7 | 0005 | 0.177 ms | 14 | 0.212 ms | 111295.752270 s | 111295.752481 s |
(s)RCU:9 | 0007 | 0.161 ms | 47 | 2.022 ms | 111295.402159 s | 111295.404181 s |
(s)NET_RX:3 | 0003 | 0.149 ms | 12 | 1.261 ms | 111301.192964 s | 111301.194225 s |
(s)TIMER:1 | 0001 | 0.105 ms | 9 | 0.198 ms | 111301.180191 s | 111301.180389 s |
... <SNIP> ...
(s)NET_RX:3 | 0002 | 0.098 ms | 6 | 0.124 ms | 111295.403760 s | 111295.403884 s |
(s)SCHED:7 | 0001 | 0.093 ms | 19 | 0.242 ms | 111301.180256 s | 111301.180498 s |
(s)SCHED:7 | 0007 | 0.078 ms | 15 | 0.188 ms | 111300.064226 s | 111300.064415 s |
(s)SCHED:7 | 0004 | 0.077 ms | 11 | 0.213 ms | 111301.361759 s | 111301.361973 s |
(s)SCHED:7 | 0000 | 0.063 ms | 33 | 0.805 ms | 111295.401811 s | 111295.402616 s |
(s)SCHED:7 | 0003 | 0.063 ms | 14 | 0.085 ms | 111301.192255 s | 111301.192340 s |
--------------------------------------------------------------------------------------------------------------------------------

Trace softirq latency with cpu filter:

# perf kwork -k softirq lat -b -C 1
Starting trace, Hit <Ctrl+C> to stop and report
^C
Kwork Name | Cpu | Avg delay | Count | Max delay | Max delay start | Max delay end |
--------------------------------------------------------------------------------------------------------------------------------
(s)RCU:9 | 0001 | 0.178 ms | 5 | 0.572 ms | 111435.534135 s | 111435.534707 s |
--------------------------------------------------------------------------------------------------------------------------------

Trace softirq latency with name filter:

# perf kwork -k softirq lat -b -n SCHED
Starting trace, Hit <Ctrl+C> to stop and report
^C
Kwork Name | Cpu | Avg delay | Count | Max delay | Max delay start | Max delay end |
--------------------------------------------------------------------------------------------------------------------------------
(s)SCHED:7 | 0001 | 0.295 ms | 15 | 2.183 ms | 111452.534950 s | 111452.537133 s |
(s)SCHED:7 | 0002 | 0.215 ms | 10 | 0.315 ms | 111460.000238 s | 111460.000553 s |
(s)SCHED:7 | 0005 | 0.190 ms | 29 | 0.338 ms | 111457.032538 s | 111457.032876 s |
(s)SCHED:7 | 0003 | 0.097 ms | 10 | 0.319 ms | 111452.434351 s | 111452.434670 s |
(s)SCHED:7 | 0006 | 0.089 ms | 1 | 0.089 ms | 111450.737450 s | 111450.737539 s |
(s)SCHED:7 | 0007 | 0.085 ms | 17 | 0.169 ms | 111452.471333 s | 111452.471502 s |
(s)SCHED:7 | 0004 | 0.071 ms | 15 | 0.221 ms | 111452.535252 s | 111452.535473 s |
(s)SCHED:7 | 0000 | 0.044 ms | 32 | 0.130 ms | 111460.001982 s | 111460.002112 s |
--------------------------------------------------------------------------------------------------------------------------------

Signed-off-by: Yang Jihong <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paul Clarke <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ Add {} for multiline if blocks ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/bpf_kwork.c

···
 	.get_work_name = get_work_name_from_map,
 };
 
+static void softirq_load_prepare(struct perf_kwork *kwork)
+{
+	if (kwork->report == KWORK_REPORT_RUNTIME) {
+		bpf_program__set_autoload(skel->progs.report_softirq_entry, true);
+		bpf_program__set_autoload(skel->progs.report_softirq_exit, true);
+	} else if (kwork->report == KWORK_REPORT_LATENCY) {
+		bpf_program__set_autoload(skel->progs.latency_softirq_raise, true);
+		bpf_program__set_autoload(skel->progs.latency_softirq_entry, true);
+	}
+}
+
+static struct kwork_class_bpf kwork_softirq_bpf = {
+	.load_prepare  = softirq_load_prepare,
+	.get_work_name = get_work_name_from_map,
+};
+
 static struct kwork_class_bpf *
 kwork_class_bpf_supported_list[KWORK_CLASS_MAX] = {
 	[KWORK_CLASS_IRQ]       = &kwork_irq_bpf,
-	[KWORK_CLASS_SOFTIRQ]   = NULL,
+	[KWORK_CLASS_SOFTIRQ]   = &kwork_softirq_bpf,
 	[KWORK_CLASS_WORKQUEUE] = NULL,
 };
 

tools/perf/util/bpf_skel/kwork_trace.bpf.c

···
 	return update_timeend(&perf_kwork_report, &perf_kwork_time, &key);
 }
 
+static char softirq_name_list[NR_SOFTIRQS][MAX_KWORKNAME] = {
+	{ "HI"       },
+	{ "TIMER"    },
+	{ "NET_TX"   },
+	{ "NET_RX"   },
+	{ "BLOCK"    },
+	{ "IRQ_POLL" },
+	{ "TASKLET"  },
+	{ "SCHED"    },
+	{ "HRTIMER"  },
+	{ "RCU"      },
+};
+
+SEC("tracepoint/irq/softirq_entry")
+int report_softirq_entry(struct trace_event_raw_softirq *ctx)
+{
+	unsigned int vec = ctx->vec;
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.cpu  = bpf_get_smp_processor_id(),
+		.id   = (__u64)vec,
+	};
+
+	if (vec < NR_SOFTIRQS) {
+		return update_timestart_and_name(&perf_kwork_time,
+						 &perf_kwork_names, &key,
+						 softirq_name_list[vec]);
+	}
+
+	return 0;
+}
+
+SEC("tracepoint/irq/softirq_exit")
+int report_softirq_exit(struct trace_event_raw_softirq *ctx)
+{
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.cpu  = bpf_get_smp_processor_id(),
+		.id   = (__u64)ctx->vec,
+	};
+
+	return update_timeend(&perf_kwork_report, &perf_kwork_time, &key);
+}
+
+SEC("tracepoint/irq/softirq_raise")
+int latency_softirq_raise(struct trace_event_raw_softirq *ctx)
+{
+	unsigned int vec = ctx->vec;
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.cpu  = bpf_get_smp_processor_id(),
+		.id   = (__u64)vec,
+	};
+
+	if (vec < NR_SOFTIRQS) {
+		return update_timestart_and_name(&perf_kwork_time,
+						 &perf_kwork_names, &key,
+						 softirq_name_list[vec]);
+	}
+
+	return 0;
+}
+
+SEC("tracepoint/irq/softirq_entry")
+int latency_softirq_entry(struct trace_event_raw_softirq *ctx)
+{
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.cpu  = bpf_get_smp_processor_id(),
+		.id   = (__u64)ctx->vec,
+	};
+
+	return update_timeend(&perf_kwork_report, &perf_kwork_time, &key);
+}
+
 char LICENSE[] SEC("license") = "Dual BSD/GPL";