Em Tue, Jan 08, 2019 at 07:38:10AM +0000, Andrii Nakryiko escreveu:
> When dealing with BTF encoding of multiple CUs, special `void` type
> should be handled explicitly. This is already handled for all BTF
> types except recently added FUNC_PROTO. Without this fix, any `void`
> type directly referenced from FUNC_PROTO will turn into last type
> from previous CU (see example below, for FUNC_PROTO [4]).
>
> $ cat test1.c
> void (*foo)(void);
>
> int main() {
> return 0;
> }
>
> $ cat test2.c
> void (*bar)(void);
>
> $ cc -g test1.c test2.c -o test
>
> Without fix:
>
> $ LLVM_OBJCOPY=objcopy ~/local/pahole/build/pahole -JV /tmp/test
> File /tmp/test:
> [1] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
> [2] FUNC_PROTO (anon) return=0 args=(void)
> [3] PTR (anon) type_id=2
> [4] FUNC_PROTO (anon) return=3 args=(void)
> [5] PTR (anon) type_id=4
Reproduced the problem, but couldn't so far try the fix as the patch
came mangled, see below, fixing it by hand, probably related to some MS
outlook setting:
Content-ID: <02DD2D329C450C4FB23C8218B6842E31@xxxxxxxxxxxxxxxxxxxxxxxxx>
i--- a/libbtf.c
+++ b/libbtf.c
@@ -535,7 +535,7 @@ int32_t btf__add_func_proto(struct btf *btf, struct fty=
pe *ftype,
=20
t.name_off =3D 0;
t.info =3D BTF_INFO_ENCODE(BTF_KIND_FUNC_PROTO, 0, nr_params);
- t.type =3D type_id_off + ftype->tag.type;
+ t.type =3D ftype->tag.type =3D=3D 0 ? 0 : type_id_off + ftype->tag.type;
=20
++btf->type_index;
if (gobuffer__add(&btf->types, &t, sizeof(t)) >=3D 0) {
