[v2,bpf-next,5/6] bpf: add bpf_modify_return_test_tp() kfunc triggering tracepoint

Commit Message

Andrii Nakryiko March 26, 2024, 4:21 p.m. UTC

Add a simple bpf_modify_return_test_tp() kfunc, available to all program
types, that is useful for various testing and benchmarking scenarios, as
it allows to trigger most tracing BPF program types from BPF side,
allowing to do complex testing and benchmarking scenarios.

It is also attachable to for fmod_ret programs, making it a good and
simple way to trigger fmod_ret program under test/benchmark.

Signed-off-by: Andrii Nakryiko <[e-mail]>
---
 include/trace/events/bpf_test_run.h | 17 +++++++++++++++++
 kernel/bpf/helpers.c                |  1 +
 net/bpf/test_run.c                  |  8 ++++++++
 3 files changed, 26 insertions(+)

Patch

diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
index 265447e3f71a..0c924d39b7cb 100644
--- a/include/trace/events/bpf_test_run.h
+++ b/include/trace/events/bpf_test_run.h
@@ -7,6 +7,23 @@ 
 
 #include <linux/tracepoint.h>
 
+TRACE_EVENT(bpf_trigger_tp,
+
+	TP_PROTO(int nonce),
+
+	TP_ARGS(nonce),
+
+	TP_STRUCT__entry(
+		__field(int, nonce)
+	),
+
+	TP_fast_assign(
+		__entry->nonce = nonce;
+	),
+
+	TP_printk("nonce %d", __entry->nonce)
+);
+
 DECLARE_EVENT_CLASS(bpf_test_finish,
 
 	TP_PROTO(int *err),
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9234174ccb21..f89c35a17546 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2625,6 +2625,7 @@  BTF_ID_FLAGS(func, bpf_dynptr_is_null)
 BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
 BTF_ID_FLAGS(func, bpf_dynptr_size)
 BTF_ID_FLAGS(func, bpf_dynptr_clone)
+BTF_ID_FLAGS(func, bpf_modify_return_test_tp)
 BTF_KFUNCS_END(common_btf_ids)
 
 static const struct btf_kfunc_id_set common_kfunc_set = {
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 61efeadaff8d..f6aad4ed2ab2 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -575,6 +575,13 @@  __bpf_kfunc int bpf_modify_return_test2(int a, int *b, short c, int d,
 	return a + *b + c + d + (long)e + f + g;
 }
 
+__bpf_kfunc int bpf_modify_return_test_tp(int nonce)
+{
+	trace_bpf_trigger_tp(nonce);
+
+	return nonce;
+}
+
 int noinline bpf_fentry_shadow_test(int a)
 {
 	return a + 1;
@@ -622,6 +629,7 @@  __bpf_kfunc_end_defs();
 BTF_KFUNCS_START(bpf_test_modify_return_ids)
 BTF_ID_FLAGS(func, bpf_modify_return_test)
 BTF_ID_FLAGS(func, bpf_modify_return_test2)
+BTF_ID_FLAGS(func, bpf_modify_return_test_tp)
 BTF_ID_FLAGS(func, bpf_fentry_test1, KF_SLEEPABLE)
 BTF_KFUNCS_END(bpf_test_modify_return_ids)