From: Alexei Starovoitov <ast@xxxxxxxxxx>
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 <ast@xxxxxxxxxx>
---
tools/lib/bpf/bpf_helpers.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 7d12d3e620cc..b49823117dae 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -177,6 +177,9 @@ 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
--
2.34.1
