[PATCH bpf-next 08/13] bpftool gen: embed loader prog BTF in the lskel header

[KP Singh <kpsingh@kernel.org>]

Extend the signed lskel codegen to include the loader prog BTF in
the generated header and the PKCS#7 signature scope. The loader
needs this BTF at load time so the kernel can resolve kfunc calls
by name.

Lskels generated without -S are unchanged; the new codegen is gated
on opts.btf_sz.

Signed-off-by: KP Singh <kpsingh@kernel.org>
---
 tools/bpf/bpftool/gen.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 2f9e10752e28..95dba5c53ef4 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -793,6 +793,8 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 	if (sign_progs) {
 		sopts.insns = opts.insns;
 		sopts.insns_sz = opts.insns_sz;
+		sopts.btf = opts.btf;
+		sopts.btf_sz = opts.btf_sz;
 		sopts.excl_prog_hash = prog_sha;
 		sopts.excl_prog_hash_sz = sizeof(prog_sha);
 		sopts.signature = sig_buf;
@@ -822,6 +824,17 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 		\n\
 		\";\n");
 
+		if (opts.btf_sz) {
+			codegen("\
+			\n\
+				static const char opts_btf[] __attribute__((__aligned__(8))) = \"\\\n\
+			");
+			print_hex(opts.btf, opts.btf_sz);
+			codegen("\
+			\n\
+			\";\n");
+		}
+
 		codegen("\
 		\n\
 			opts.signature = (void *)opts_sig;			\n\
@@ -830,6 +843,14 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 			opts.excl_prog_hash_sz = sizeof(opts_excl_hash) - 1;	\n\
 			opts.keyring_id = skel->keyring_id;			\n\
 		");
+
+		if (opts.btf_sz) {
+			codegen("\
+			\n\
+				opts.btf = (void *)opts_btf;			    \n\
+				opts.btf_sz = sizeof(opts_btf) - 1;		    \n\
+			");
+		}
 	}
 
 	codegen("\
-- 
2.53.0