Re: [PATCH bpf-next] bpftool: Preserve unsigned enum64 values in data dumps

["Alexei Starovoitov" <alexei.starovoitov@gmail.com>]

On Sat, Oct 31, 2026 at 03:36 PM Hungyu Lin <dennylin0707@gmail.com> wrote:
> @@ -204,7 +204,10 @@ static int btf_dumper_enum64(const struct btf_dumper *d,
> -	jsonw_int(d->jw, value);
> +	if (btf_kflag(t))
> +		jsonw_int(d->jw, value);
> +	else
> +		jsonw_uint(d->jw, value);

btf_dumper_enum() has the same problem.

Fix all in one patch:

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index 3267163..09dd428 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -149,7 +149,8 @@ static int btf_dumper_enum(const struct btf_dumper *d,
 			    const void *data)
 {
 	const struct btf_enum *enums = btf_enum(t);
-	__s64 value;
+	bool is_signed = btf_kflag(t);
+	__s64 value, val;
 	__u32 i;

 	switch (t->size) {
@@ -157,20 +158,21 @@ static int btf_dumper_enum(const struct btf_dumper *d,
 		value = *(__s64 *)data;
 		break;
 	case 4:
-		value = *(__s32 *)data;
+		value = is_signed ? (__s64)*(__s32 *)data : *(__u32 *)data;
 		break;
 	case 2:
-		value = *(__s16 *)data;
+		value = is_signed ? *(__s16 *)data : *(__u16 *)data;
 		break;
 	case 1:
-		value = *(__s8 *)data;
+		value = is_signed ? *(__s8 *)data : *(__u8 *)data;
 		break;
 	default:
 		return -EINVAL;
 	}

 	for (i = 0; i < btf_vlen(t); i++) {
-		if (value == enums[i].val) {
+		val = is_signed ? (__s64)enums[i].val : (__u32)enums[i].val;
+		if (value == val) {
 			jsonw_string(d->jw,
 				     btf__name_by_offset(d->btf,
 							 enums[i].name_off));
@@ -178,7 +180,10 @@ static int btf_dumper_enum(const struct btf_dumper *d,
 		}
 	}

-	jsonw_int(d->jw, value);
+	if (is_signed)
+		jsonw_int(d->jw, value);
+	else
+		jsonw_uint(d->jw, value);
 	return 0;
 }

@@ -204,7 +209,10 @@ static int btf_dumper_enum64(const struct btf_dumper *d,
 		}
 	}

-	jsonw_int(d->jw, value);
+	if (btf_kflag(t))
+		jsonw_int(d->jw, value);
+	else
+		jsonw_uint(d->jw, value);
 	return 0;
 }


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