Commit 6c66b0e7 authored by Dave Marchevsky's avatar Dave Marchevsky Committed by Alexei Starovoitov
Browse files

libbpf: Use static const fmt string in __bpf_printk 



The __bpf_printk convenience macro was using a 'char' fmt string holder
as it predates support for globals in libbpf. Move to more efficient
'static const char', but provide a fallback to the old way via
BPF_NO_GLOBAL_DATA so users on old kernels can still use the macro.

Signed-off-by: default avatarDave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-6-davemarchevsky@fb.com
parent c2758baa

tools/lib/bpf/bpf_helpers.h

+7 −1
Original line number Diff line number Diff line
@@ -216,9 +216,15 @@ enum libbpf_tristate { 
		     ___param, sizeof(___param));		\

})



#ifdef BPF_NO_GLOBAL_DATA

#define BPF_PRINTK_FMT_MOD

#else

#define BPF_PRINTK_FMT_MOD static const

#endif



#define __bpf_printk(fmt, ...)				\

({							\

	char ____fmt[] = fmt;				\

	BPF_PRINTK_FMT_MOD char ____fmt[] = fmt;	\

	bpf_trace_printk(____fmt, sizeof(____fmt),	\

			 ##__VA_ARGS__);		\

})