From 5cbd3fe3a91df46ea201cc5d8ab4e390332ec26e Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 17 Mar 2023 13:19:19 -0700 Subject: [PATCH] libbpf: Introduce bpf_ksym_exists() macro. Introduce bpf_ksym_exists() macro that can be used by BPF programs to detect at load time whether particular ksym (either variable or kfunc) is present in the kernel. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230317201920.62030-4-alexei.starovoitov@gmail.com --- tools/lib/bpf/bpf_helpers.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index 7d12d3e..e7e1a8a 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -177,6 +177,11 @@ enum libbpf_tristate { #define __kptr_untrusted __attribute__((btf_type_tag("kptr_untrusted"))) #define __kptr __attribute__((btf_type_tag("kptr"))) +#define bpf_ksym_exists(sym) ({ \ + _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ + !!sym; \ +}) + #ifndef ___bpf_concat #define ___bpf_concat(a, b) a ## b #endif -- 2.7.4