From 45251bcfe031d15a3885ac15f874f65ef4580ed3 Mon Sep 17 00:00:00 2001 From: Alan Maguire Date: Mon, 19 May 2025 17:59:34 +0100 Subject: [PATCH] libbpf/btf: Fix string handling to support multi-split BTF [ Upstream commit 4e29128a9acec2a622734844bedee013e2901bdf ] 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 Signed-off-by: Sasha Levin --- tools/lib/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 27e7bfae953b..4a486798fe4c 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -995,7 +995,7 @@ 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; }