From: Alan Maguire Date: Mon, 19 May 2025 16:59:34 +0000 (+0100) Subject: libbpf/btf: Fix string handling to support multi-split BTF X-Git-Tag: v6.16-rc1~131^2~18^2~1 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=4e29128a9acec2a622734844bedee013e2901bdf;p=linux-2.6-block.git libbpf/btf: Fix string handling to support multi-split BTF libbpf handling of split BTF has been written largely with the assumption that multiple splits are possible, i.e. split BTF on top of split BTF on top of base BTF. One area where this does not quite work is string handling in split BTF; the start string offset should be the base BTF string section length + the base BTF string offset. This worked in the past because for a single split BTF with base the start string offset was always 0. Signed-off-by: Alan Maguire Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250519165935.261614-2-alan.maguire@oracle.com --- diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index f18d7e6a453c..8d0d0b645a75 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -996,7 +996,7 @@ static struct btf *btf_new_empty(struct btf *base_btf) if (base_btf) { btf->base_btf = base_btf; btf->start_id = btf__type_cnt(base_btf); - btf->start_str_off = base_btf->hdr->str_len; + btf->start_str_off = base_btf->hdr->str_len + base_btf->start_str_off; btf->swapped_endian = base_btf->swapped_endian; }