[PATCH bpf-next v3 09/12] libbpf: Add bpf_stream_printk() macro

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

Add a convenience macro to print data to the BPF streams. BPF_STDOUT and
BPF_STDERR stream IDs in the vmlinux.h can be passed to the macro to
print to the respective streams.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 tools/lib/bpf/bpf_helpers.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index a50773d4616e..76b127a9f24d 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -314,6 +314,22 @@ enum libbpf_tristate {
 			  ___param, sizeof(___param));		\
 })
 
+extern int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args,
+			      __u32 len__sz, void *aux__prog) __weak __ksym;
+
+#define bpf_stream_printk(stream_id, fmt, args...)				\
+({										\
+	static const char ___fmt[] = fmt;					\
+	unsigned long long ___param[___bpf_narg(args)];				\
+										\
+	_Pragma("GCC diagnostic push")						\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")			\
+	___bpf_fill(___param, args);						\
+	_Pragma("GCC diagnostic pop")						\
+										\
+	bpf_stream_vprintk(stream_id, ___fmt, ___param, sizeof(___param), NULL);\
+})
+
 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
  * Otherwise use __bpf_vprintk
  */
-- 
2.47.1