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Date: Thu, 6 Aug 2020 17:10:03 -0700 From: Alexei Starovoitov <alexei.starovoitov@...il.com> To: Andrii Nakryiko <andrii.nakryiko@...il.com> Cc: Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>, Alexei Starovoitov <ast@...com>, Daniel Borkmann <daniel@...earbox.net>, Kernel Team <kernel-team@...com> Subject: Re: [RFC PATCH bpf-next 7/9] selftests/bpf: add CO-RE relo test for TYPE_ID_LOCAL/TYPE_ID_TARGET On Thu, Aug 06, 2020 at 04:48:27PM -0700, Andrii Nakryiko wrote: > On Thu, Aug 6, 2020 at 3:30 PM Alexei Starovoitov > <alexei.starovoitov@...il.com> wrote: > > > > On Tue, Aug 04, 2020 at 11:24:07AM -0700, Andrii Nakryiko wrote: > > > + > > > +SEC("raw_tracepoint/sys_enter") > > > +int test_core_type_id(void *ctx) > > > +{ > > > + struct core_reloc_type_id_output *out = (void *)&data.out; > > > + > > > + out->local_anon_struct = bpf_core_type_id_local(struct { int marker_field; }); > > > + out->local_anon_union = bpf_core_type_id_local(union { int marker_field; }); > > > + out->local_anon_enum = bpf_core_type_id_local(enum { MARKER_ENUM_VAL = 123 }); > > > + out->local_anon_func_proto_ptr = bpf_core_type_id_local(_Bool(*)(int)); > > > + out->local_anon_void_ptr = bpf_core_type_id_local(void *); > > > + out->local_anon_arr = bpf_core_type_id_local(_Bool[47]); > > > + > > > + out->local_struct = bpf_core_type_id_local(struct a_struct); > > > + out->local_union = bpf_core_type_id_local(union a_union); > > > + out->local_enum = bpf_core_type_id_local(enum an_enum); > > > + out->local_int = bpf_core_type_id_local(int); > > > + out->local_struct_typedef = bpf_core_type_id_local(named_struct_typedef); > > > + out->local_func_proto_typedef = bpf_core_type_id_local(func_proto_typedef); > > > + out->local_arr_typedef = bpf_core_type_id_local(arr_typedef); > > > + > > > + out->targ_struct = bpf_core_type_id_kernel(struct a_struct); > > > + out->targ_union = bpf_core_type_id_kernel(union a_union); > > > + out->targ_enum = bpf_core_type_id_kernel(enum an_enum); > > > + out->targ_int = bpf_core_type_id_kernel(int); > > > + out->targ_struct_typedef = bpf_core_type_id_kernel(named_struct_typedef); > > > + out->targ_func_proto_typedef = bpf_core_type_id_kernel(func_proto_typedef); > > > + out->targ_arr_typedef = bpf_core_type_id_kernel(arr_typedef); > > > > bpf_core_type_id_kernel() returns btf_id of the type in vmlinux BTF or zero, > > so what is the point of above tests? All targ_* will be zero. > > Should the test find a type that actually exists in the kernel? > > What am I missing? > > Probably, that for almost all core_reloc tests, "kernel BTF" comes > from specially-crafted BTFs, like btf__core_reloc_type_id*.c for this > set of tests. Only one core_reloc sub-test actually loads real kernel > BTF, for all others we have a "controlled environment" set up. ahh. right. > But on another note. I opted to make all type-based relocations to > return 0 if target type is not found, but now I'm thinking that maybe > for TYPE_SIZE and TYPE_ID_KERNEL we should fail them, just like > field-based ones, if type is not found. Makes it harder to miss that > something changed in the new kernel version. WDYT? makes sense to me. If we ever need non-failing type_id_kernel() we can add it later, right?
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