From: Alexei Starovoitov Date: Fri, 17 Mar 2023 20:19:18 +0000 (-0700) Subject: libbpf: Fix relocation of kfunc ksym in ld_imm64 insn. X-Git-Tag: v6.6.7~2736^2~129^2~76^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5fc13ad59b60708e52932188854d4d5bf2b0e10e;p=platform%2Fkernel%2Flinux-starfive.git libbpf: Fix relocation of kfunc ksym in ld_imm64 insn. void *p = kfunc; -> generates ld_imm64 insn. kfunc() -> generates bpf_call insn. libbpf patches bpf_call insn correctly while only btf_id part of ld_imm64 is set in the former case. Which means that pointers to kfuncs in modules are not patched correctly and the verifier rejects load of such programs due to btf_id being out of range. Fix libbpf to patch ld_imm64 for kfunc. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230317201920.62030-3-alexei.starovoitov@gmail.com --- diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a557718..4c34fbd 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -7533,6 +7533,12 @@ static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj, ext->is_set = true; ext->ksym.kernel_btf_id = kfunc_id; ext->ksym.btf_fd_idx = mod_btf ? mod_btf->fd_array_idx : 0; + /* Also set kernel_btf_obj_fd to make sure that bpf_object__relocate_data() + * populates FD into ld_imm64 insn when it's used to point to kfunc. + * {kernel_btf_id, btf_fd_idx} -> fixup bpf_call. + * {kernel_btf_id, kernel_btf_obj_fd} -> fixup ld_imm64. + */ + ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0; pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n", ext->name, kfunc_id);