[RFC,bpf-next,07/14] bpf: save the start of functions in bpf_prog_aux

Commit Message

Anton Protopopov March 18, 2025, 2:33 p.m. UTC

Introduce a new subprog_start field in bpf_prog_aux. This field may
be used by JIT compilers wanting to know the real absolute xlated
offset of the function being jitted. The func_info[func_id] may have
served this purpose, but func_info may be NULL, so JIT compilers
can't rely on it.

Signed-off-by: Anton Protopopov <[e-mail]>
---
 include/linux/bpf.h   | 1 +
 kernel/bpf/verifier.c | 1 +
 2 files changed, 2 insertions(+)

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 42ddd2b61866..fb0910083b79 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1524,6 +1524,7 @@  struct bpf_prog_aux {
 	u32 ctx_arg_info_size;
 	u32 max_rdonly_access;
 	u32 max_rdwr_access;
+	u32 subprog_start;
 	struct btf *attach_btf;
 	struct bpf_ctx_arg_aux *ctx_arg_info;
 	void __percpu *priv_stack_ptr;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0860ef57d5af..7f66002071ed 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20999,6 +20999,7 @@  static int jit_subprogs(struct bpf_verifier_env *env)
 		func[i]->aux->func_idx = i;
 		/* Below members will be freed only at prog->aux */
 		func[i]->aux->btf = prog->aux->btf;
+		func[i]->aux->subprog_start = subprog_start;
 		func[i]->aux->func_info = prog->aux->func_info;
 		func[i]->aux->func_info_cnt = prog->aux->func_info_cnt;
 		func[i]->aux->poke_tab = prog->aux->poke_tab;