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SubjectRe: [PATCH bpf-next v6 06/23] selftests/bpf: Add tests for kfunc returning a memory pointer
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On 7/12/22 7:58 AM, Benjamin Tissoires wrote:
> We add 2 new kfuncs that are following the RET_PTR_TO_MEM
> capability from the previous commit.
> Then we test them in selftests:
> the first tests are testing valid case, and are not failing,
> and the later ones are actually preventing the program to be loaded
> because they are wrong.
>
> To work around that, we mark the failing ones as not autoloaded
> (with SEC("?tc")), and we manually enable them one by one, ensuring
> the verifier rejects them.
>
> To be able to use bpf_program__set_autoload() from libbpf, we need
> to use a plain skeleton, not a light-skeleton, and this is why we
> also change the Makefile to generate both for kfunc_call_test.c
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
>
> ---
>
> new in v6
> ---
> include/linux/btf.h | 4 +-
> net/bpf/test_run.c | 22 +++++
> tools/testing/selftests/bpf/Makefile | 5 +-
> .../selftests/bpf/prog_tests/kfunc_call.c | 48 ++++++++++
> .../selftests/bpf/progs/kfunc_call_test.c | 89 +++++++++++++++++++
> 5 files changed, 165 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index 31da4273c2ec..6f46ff2128ae 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -422,7 +422,9 @@ static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dt
>
> static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
> {
> - /* t comes in already as a pointer */
> + if (!btf_type_is_ptr(t))
> + return false;

Why we have a change here?

> +
> t = btf_type_by_id(btf, t->type);
>
> /* allow const */
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index 9da2a42811e8..0b4026ea4652 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -606,6 +606,24 @@ noinline void bpf_kfunc_call_memb1_release(struct prog_test_member1 *p)
> WARN_ON_ONCE(1);
> }
>
> +static int *__bpf_kfunc_call_test_get_mem(struct prog_test_ref_kfunc *p, const int size)
> +{
> + if (size > 2 * sizeof(int))
> + return NULL;
> +
> + return (int *)p;
> +}
> +
> +noinline int *bpf_kfunc_call_test_get_rdwr_mem(struct prog_test_ref_kfunc *p, const int rdwr_buf_size)
> +{
> + return __bpf_kfunc_call_test_get_mem(p, rdwr_buf_size);
> +}
> +
> +noinline int *bpf_kfunc_call_test_get_rdonly_mem(struct prog_test_ref_kfunc *p, const int rdonly_buf_size)
> +{
> + return __bpf_kfunc_call_test_get_mem(p, rdonly_buf_size);
> +}
> +
> noinline struct prog_test_ref_kfunc *
> bpf_kfunc_call_test_kptr_get(struct prog_test_ref_kfunc **pp, int a, int b)
> {
> @@ -704,6 +722,8 @@ BTF_ID(func, bpf_kfunc_call_memb_acquire)
> BTF_ID(func, bpf_kfunc_call_test_release)
> BTF_ID(func, bpf_kfunc_call_memb_release)
> BTF_ID(func, bpf_kfunc_call_memb1_release)
> +BTF_ID(func, bpf_kfunc_call_test_get_rdwr_mem)
> +BTF_ID(func, bpf_kfunc_call_test_get_rdonly_mem)
> BTF_ID(func, bpf_kfunc_call_test_kptr_get)
> BTF_ID(func, bpf_kfunc_call_test_pass_ctx)
> BTF_ID(func, bpf_kfunc_call_test_pass1)
> @@ -731,6 +751,8 @@ BTF_SET_END(test_sk_release_kfunc_ids)
> BTF_SET_START(test_sk_ret_null_kfunc_ids)
> BTF_ID(func, bpf_kfunc_call_test_acquire)
> BTF_ID(func, bpf_kfunc_call_memb_acquire)
> +BTF_ID(func, bpf_kfunc_call_test_get_rdwr_mem)
> +BTF_ID(func, bpf_kfunc_call_test_get_rdonly_mem)
> BTF_ID(func, bpf_kfunc_call_test_kptr_get)
> BTF_SET_END(test_sk_ret_null_kfunc_ids)
>
[...]

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