From 8cee9107e72c93a52a7f2c58658c99887bdb05e0 Mon Sep 17 00:00:00 2001 From: Luigi Rizzo Date: Mon, 5 Oct 2020 15:45:28 -0700 Subject: [PATCH] bpf, libbpf: Use valid btf in bpf_program__set_attach_target bpf_program__set_attach_target(prog, fd, ...) will always fail when fd = 0 (attach to a kernel symbol) because obj->btf_vmlinux is NULL and there is no way to set it (at the moment btf_vmlinux is meant to be temporary storage for use in bpf_object__load_xattr()). Fix this by using libbpf_find_vmlinux_btf_id(). At some point we may want to opportunistically cache btf_vmlinux so it can be reused with multiple programs. Signed-off-by: Luigi Rizzo Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Acked-by: Petar Penkov Link: https://lore.kernel.org/bpf/20201005224528.389097-1-lrizzo@google.com --- tools/lib/bpf/libbpf.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 9f90d1a..faec389 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10451,9 +10451,8 @@ int bpf_program__set_attach_target(struct bpf_program *prog, btf_id = libbpf_find_prog_btf_id(attach_func_name, attach_prog_fd); else - btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, - attach_func_name, - prog->expected_attach_type); + btf_id = libbpf_find_vmlinux_btf_id(attach_func_name, + prog->expected_attach_type); if (btf_id < 0) return btf_id; -- 2.7.4