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selftests/bpf: add btf_dedup test of FWD/STRUCT resolution 

This patch adds a btf_dedup test exercising logic of STRUCT<->FWD
resolution and validating that STRUCT is not resolved to a FWD. It also
forces hash collisions, forcing both FWD and STRUCT to be candidates for
each other. Previously this condition caused infinite loop due to FWD
pointing to STRUCT and STRUCT pointing to its FWD.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Andrii Nakryiko 2019-02-28 15:31:25 -08:00 committed by Daniel Borkmann
parent 91097fbee4
commit 7c7a4890c8
1 changed files with 45 additions and 0 deletions
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45
tools/testing/selftests/bpf/test_btf.c
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@ -5731,6 +5731,51 @@ const struct btf_dedup_test dedup_tests[] = {
.dont_resolve_fwds = false,
},
},
{
.descr = "dedup: struct <-> fwd resolution w/ hash collision",
/*
* // CU 1:
* struct x;
* struct s {
* struct x *x;
* };
* // CU 2:
* struct x {};
* struct s {
* struct x *x;
* };
*/
.input = {
.raw_types = {
/* CU 1 */
BTF_FWD_ENC(NAME_TBD, 0 /* struct fwd */), /* [1] fwd x */
BTF_PTR_ENC(1), /* [2] ptr -> [1] */
BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [3] struct s */
BTF_MEMBER_ENC(NAME_TBD, 2, 0),
/* CU 2 */
BTF_STRUCT_ENC(NAME_TBD, 0, 0), /* [4] struct x */
BTF_PTR_ENC(4), /* [5] ptr -> [4] */
BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [6] struct s */
BTF_MEMBER_ENC(NAME_TBD, 5, 0),
BTF_END_RAW,
},
BTF_STR_SEC("\0x\0s\0x\0x\0s\0x\0"),
},
.expect = {
.raw_types = {
BTF_PTR_ENC(3), /* [1] ptr -> [3] */
BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [2] struct s */
BTF_MEMBER_ENC(NAME_TBD, 1, 0),
BTF_STRUCT_ENC(NAME_NTH(2), 0, 0), /* [3] struct x */
BTF_END_RAW,
},
BTF_STR_SEC("\0s\0x"),
},
.opts = {
.dont_resolve_fwds = false,
.dedup_table_size = 1, /* force hash collisions */
},
},
{
.descr = "dedup: all possible kinds (no duplicates)",
.input = {