linux-kernel - [PATCH bpf-next v1 09/10] bpf: Add bpf_stream_vprintk with KF_IMPLICIT

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Message-ID: <20260109184852.1089786-10-ihor.solodrai@linux.dev>
Date: Fri,  9 Jan 2026 10:48:51 -0800
From: Ihor Solodrai <ihor.solodrai@...ux.dev>
To: Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>
Cc: Mykyta Yatsenko <yatsenko@...a.com>,
	Tejun Heo <tj@...nel.org>,
	Alan Maguire <alan.maguire@...cle.com>,
	Benjamin Tissoires <bentiss@...nel.org>,
	Jiri Kosina <jikos@...nel.org>,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-input@...r.kernel.org,
	sched-ext@...ts.linux.dev
Subject: [PATCH bpf-next v1 09/10] bpf: Add bpf_stream_vprintk with KF_IMPLICIT_ARGS

Implement bpf_stream_vprintk with an implicit bpf_prog_aux argument,
and change bpf_stream_vprintk_impl to call the new kfunc.

Update the selftests to use the new API with implicit argument.

bpf_stream_vprintk macro is changed to use the new bpf_stream_vprintk
kfunc, and the extern definition of bpf_stream_vprintk_impl is
replaced accordingly.

Signed-off-by: Ihor Solodrai <ihor.solodrai@...ux.dev>
---
 kernel/bpf/helpers.c                            |  1 +
 kernel/bpf/stream.c                             | 11 ++++++++---
 tools/lib/bpf/bpf_helpers.h                     |  6 +++---
 tools/testing/selftests/bpf/progs/stream_fail.c |  6 +++---
 4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 2e01973f2c18..b35b78c08583 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -4558,6 +4558,7 @@ BTF_ID_FLAGS(func, bpf_strncasestr);
 #if defined(CONFIG_BPF_LSM) && defined(CONFIG_CGROUPS)
 BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU)
 #endif
+BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS)
 BTF_ID_FLAGS(func, bpf_stream_vprintk_impl)
 BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_IMPLICIT_ARGS)
 BTF_ID_FLAGS(func, bpf_task_work_schedule_signal_impl)
diff --git a/kernel/bpf/stream.c b/kernel/bpf/stream.c
index 0b6bc3f30335..4e4713d9c771 100644
--- a/kernel/bpf/stream.c
+++ b/kernel/bpf/stream.c
@@ -212,14 +212,13 @@ __bpf_kfunc_start_defs();
  * Avoid using enum bpf_stream_id so that kfunc users don't have to pull in the
  * enum in headers.
  */
-__bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
-					u32 len__sz, void *aux__prog)
+__bpf_kfunc int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args,
+				   u32 len__sz, struct bpf_prog_aux *aux)
 {
 	struct bpf_bprintf_data data = {
 		.get_bin_args	= true,
 		.get_buf	= true,
 	};
-	struct bpf_prog_aux *aux = aux__prog;
 	u32 fmt_size = strlen(fmt__str) + 1;
 	struct bpf_stream *stream;
 	u32 data_len = len__sz;
@@ -246,6 +245,12 @@ __bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, con
 	return ret;
 }
 
+__bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
+					u32 len__sz, void *aux__prog)
+{
+	return bpf_stream_vprintk(stream_id, fmt__str, args, len__sz, aux__prog);
+}
+
 __bpf_kfunc_end_defs();
 
 /* Added kfunc to common_btf_ids */
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index d4e4e388e625..c145da05a67c 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -315,8 +315,8 @@ enum libbpf_tristate {
 			  ___param, sizeof(___param));		\
 })
 
-extern int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
-				   __u32 len__sz, void *aux__prog) __weak __ksym;
+extern int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args,
+			      __u32 len__sz) __weak __ksym;
 
 #define bpf_stream_printk(stream_id, fmt, args...)					\
 ({											\
@@ -328,7 +328,7 @@ extern int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const vo
 	___bpf_fill(___param, args);							\
 	_Pragma("GCC diagnostic pop")							\
 											\
-	bpf_stream_vprintk_impl(stream_id, ___fmt, ___param, sizeof(___param), NULL);	\
+	bpf_stream_vprintk(stream_id, ___fmt, ___param, sizeof(___param));		\
 })
 
 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
diff --git a/tools/testing/selftests/bpf/progs/stream_fail.c b/tools/testing/selftests/bpf/progs/stream_fail.c
index 3662515f0107..8e8249f3521c 100644
--- a/tools/testing/selftests/bpf/progs/stream_fail.c
+++ b/tools/testing/selftests/bpf/progs/stream_fail.c
@@ -10,7 +10,7 @@ SEC("syscall")
 __failure __msg("Possibly NULL pointer passed")
 int stream_vprintk_null_arg(void *ctx)
 {
-	bpf_stream_vprintk_impl(BPF_STDOUT, "", NULL, 0, NULL);
+	bpf_stream_vprintk(BPF_STDOUT, "", NULL, 0);
 	return 0;
 }
 
@@ -18,7 +18,7 @@ SEC("syscall")
 __failure __msg("R3 type=scalar expected=")
 int stream_vprintk_scalar_arg(void *ctx)
 {
-	bpf_stream_vprintk_impl(BPF_STDOUT, "", (void *)46, 0, NULL);
+	bpf_stream_vprintk(BPF_STDOUT, "", (void *)46, 0);
 	return 0;
 }
 
@@ -26,7 +26,7 @@ SEC("syscall")
 __failure __msg("arg#1 doesn't point to a const string")
 int stream_vprintk_string_arg(void *ctx)
 {
-	bpf_stream_vprintk_impl(BPF_STDOUT, ctx, NULL, 0, NULL);
+	bpf_stream_vprintk(BPF_STDOUT, ctx, NULL, 0);
 	return 0;
 }
 
-- 
2.52.0