bpftool: Print the enum's name instead of value

This patch prints the enum's name if there is one found in
the array of btf_enum.

The commit 9eea98497951 ("bpf: fix BTF verification of enums")
has details about an enum could have any power-of-2 size (up to 8 bytes).
This patch also takes this chance to accommodate these non 4 byte
enums.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200318171637.128862-1-kafai@fb.com

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index 01cc52b..e86e240 100644 (file)
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -43,9 +43,42 @@ static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id,
        return btf_dumper_do_type(d, actual_type_id, bit_offset, data);
 }
 
-static void btf_dumper_enum(const void *data, json_writer_t *jw)
+static int btf_dumper_enum(const struct btf_dumper *d,
+                           const struct btf_type *t,
+                           const void *data)
 {
-       jsonw_printf(jw, "%d", *(int *)data);
+       const struct btf_enum *enums = btf_enum(t);
+       __s64 value;
+       __u16 i;
+
+       switch (t->size) {
+       case 8:
+               value = *(__s64 *)data;
+               break;
+       case 4:
+               value = *(__s32 *)data;
+               break;
+       case 2:
+               value = *(__s16 *)data;
+               break;
+       case 1:
+               value = *(__s8 *)data;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       for (i = 0; i < btf_vlen(t); i++) {
+               if (value == enums[i].val) {
+                       jsonw_string(d->jw,
+                                    btf__name_by_offset(d->btf,
+                                                        enums[i].name_off));
+                       return 0;
+               }
+       }
+
+       jsonw_int(d->jw, value);
+       return 0;
 }
 
 static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
@@ -366,8 +399,7 @@ static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
        case BTF_KIND_ARRAY:
                return btf_dumper_array(d, type_id, data);
        case BTF_KIND_ENUM:
-               btf_dumper_enum(data, d->jw);
-               return 0;
+               return btf_dumper_enum(d, t, data);
        case BTF_KIND_PTR:
                btf_dumper_ptr(data, d->jw, d->is_plain_text);
                return 0;