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libbpf: Ignore incompatible types with matching name during CO-RE relocation 

When finding target type candidates, ignore forward declarations, functions,
and other named types of incompatible kind. Not doing this can cause false
errors.  See [0] for one such case (due to struct pt_regs forward
declaration).

  [0] https://github.com/iovisor/bcc/pull/2806#issuecomment-598543645

Fixes: ddc7c30426 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Reported-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200313172336.1879637-3-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-03-13 10:23:34 -07:00 committed by Daniel Borkmann
parent 3e2671fb9a
commit d121e1d34b
1 changed files with 4 additions and 0 deletions
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4
tools/lib/bpf/libbpf.c
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@ -3873,6 +3873,10 @@ static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
if (str_is_empty(targ_name))
continue;
t = skip_mods_and_typedefs(targ_btf, i, NULL);
if (!btf_is_composite(t) && !btf_is_array(t))
continue;
targ_essent_len = bpf_core_essential_name_len(targ_name);
if (targ_essent_len != local_essent_len)
continue;