Re: [PATCH bpf-next v2 11/18] bpftool: Add btf enum64 support

[Yonghong Song <yhs@fb.com>]

On 5/17/22 4:38 PM, Andrii Nakryiko wrote:
> On Fri, May 13, 2022 at 8:13 PM Yonghong Song <yhs@fb.com> wrote:
>>
>> Add BTF_KIND_ENUM64 support.
>> For example, the following enum is defined in uapi bpf.h.
>>    $ cat core.c
>>    enum A {
>>          BPF_F_INDEX_MASK                = 0xffffffffULL,
>>          BPF_F_CURRENT_CPU               = BPF_F_INDEX_MASK,
>>          BPF_F_CTXLEN_MASK               = (0xfffffULL << 32),
>>    } g;
>> Compiled with
>>    clang -target bpf -O2 -g -c core.c
>> Using bpftool to dump types and generate format C file:
>>    $ bpftool btf dump file core.o
>>    ...
>>    [1] ENUM64 'A' size=8 vlen=3
>>          'BPF_F_INDEX_MASK' val=4294967295ULL
>>          'BPF_F_CURRENT_CPU' val=4294967295ULL
>>          'BPF_F_CTXLEN_MASK' val=4503595332403200ULL
>>    $ bpftool btf dump file core.o format c
>>    ...
>>    enum A {
>>          BPF_F_INDEX_MASK = 4294967295ULL,
>>          BPF_F_CURRENT_CPU = 4294967295ULL,
>>          BPF_F_CTXLEN_MASK = 4503595332403200ULL,
>>    };
>>    ...
>>
>> The 64bit value is represented properly in BTF and C dump.
>>
>> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>>   tools/bpf/bpftool/btf.c        | 49 ++++++++++++++++++++++++++++++++--
>>   tools/bpf/bpftool/btf_dumper.c | 29 ++++++++++++++++++++
>>   tools/bpf/bpftool/gen.c        |  1 +
>>   3 files changed, 77 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
>> index a2c665beda87..9e5db870fe53 100644
>> --- a/tools/bpf/bpftool/btf.c
>> +++ b/tools/bpf/bpftool/btf.c
>> @@ -40,6 +40,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
>>          [BTF_KIND_FLOAT]        = "FLOAT",
>>          [BTF_KIND_DECL_TAG]     = "DECL_TAG",
>>          [BTF_KIND_TYPE_TAG]     = "TYPE_TAG",
>> +       [BTF_KIND_ENUM64]       = "ENUM64",
>>   };
>>
>>   struct btf_attach_point {
>> @@ -228,10 +229,54 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
>>                          if (json_output) {
>>                                  jsonw_start_object(w);
>>                                  jsonw_string_field(w, "name", name);
>> -                               jsonw_uint_field(w, "val", v->val);
>> +                               if (btf_kflag(t))
>> +                                       jsonw_int_field(w, "val", v->val);
>> +                               else
>> +                                       jsonw_uint_field(w, "val", v->val);
>>                                  jsonw_end_object(w);
>>                          } else {
>> -                               printf("\n\t'%s' val=%u", name, v->val);
>> +                               if (btf_kflag(t))
>> +                                       printf("\n\t'%s' val=%d", name, v->val);
>> +                               else
>> +                                       printf("\n\t'%s' val=%u", name, v->val);
>> +                       }
>> +               }
>> +               if (json_output)
>> +                       jsonw_end_array(w);
>> +               break;
>> +       }
>> +       case BTF_KIND_ENUM64: {
>> +               const struct btf_enum64 *v = btf_enum64(t);
>> +               __u16 vlen = btf_vlen(t);
>> +               int i;
>> +
>> +               if (json_output) {
>> +                       jsonw_uint_field(w, "size", t->size);
>> +                       jsonw_uint_field(w, "vlen", vlen);
>> +                       jsonw_name(w, "values");
>> +                       jsonw_start_array(w);
>> +               } else {
>> +                       printf(" size=%u vlen=%u", t->size, vlen);
>> +               }
>> +               for (i = 0; i < vlen; i++, v++) {
>> +                       const char *name = btf_str(btf, v->name_off);
>> +                       __u64 val = ((__u64)v->val_hi32 << 32) | v->val_lo32;
>> +
>> +                       if (json_output) {
>> +                               jsonw_start_object(w);
>> +                               jsonw_string_field(w, "name", name);
> 
> forgot emitting kflag itself (both in bpftool and in selftests), let's
> add that for both enum and enum64?

will do. I will also check other places whether I missed or not.

> 
>> +                               if (btf_kflag(t))
>> +                                       jsonw_int_field(w, "val", val);
>> +                               else
>> +                                       jsonw_uint_field(w, "val", val);
>> +                               jsonw_end_object(w);
>> +                       } else {
>> +                               if (btf_kflag(t))
>> +                                       printf("\n\t'%s' val=%lldLL", name,
>> +                                              (unsigned long long)val);
>> +                               else
>> +                                       printf("\n\t'%s' val=%lluULL", name,
>> +                                              (unsigned long long)val);
>>                          }
>>                  }
>>                  if (json_output)
> 
> [...]