[PATCH bpf-next 1/2] btf: add support for VAR and DATASEC in btf_dedup()

[andrii.nakryiko]

From: Andrii Nakryiko <andr...@fb.com>

This patch adds support for VAR and DATASEC in btf_dedup(). VAR/DATASEC
are never deduplicated, but they need to be processed anyway as types
they refer to might need to be remapped due to deduplication and
compaction.

Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Yonghong Song <y...@fb.com>
Cc: Alexei Starovoitov <a...@fb.com>
Signed-off-by: Andrii Nakryiko <andr...@fb.com>
---
 tools/lib/bpf/btf.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 701e7e28ada3..75eaf10b9e1a 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1354,8 +1354,16 @@ static struct btf_dedup *btf_dedup_new(struct btf *btf, 
struct btf_ext *btf_ext,
        }
        /* special BTF "void" type is made canonical immediately */
        d->map[0] = 0;
-       for (i = 1; i <= btf->nr_types; i++)
-               d->map[i] = BTF_UNPROCESSED_ID;
+       for (i = 1; i <= btf->nr_types; i++) {
+               struct btf_type *t = d->btf->types[i];
+               __u16 kind = BTF_INFO_KIND(t->info);
+
+               /* VAR and DATASEC are never deduped and are self-canonical */
+               if (kind == BTF_KIND_VAR || kind == BTF_KIND_DATASEC)
+                       d->map[i] = i;
+               else
+                       d->map[i] = BTF_UNPROCESSED_ID;
+       }
 
        d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
        if (!d->hypot_map) {
@@ -1946,6 +1954,8 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 
type_id)
        case BTF_KIND_UNION:
        case BTF_KIND_FUNC:
        case BTF_KIND_FUNC_PROTO:
+       case BTF_KIND_VAR:
+       case BTF_KIND_DATASEC:
                return 0;
 
        case BTF_KIND_INT:
@@ -2699,6 +2709,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, 
__u32 type_id)
        case BTF_KIND_PTR:
        case BTF_KIND_TYPEDEF:
        case BTF_KIND_FUNC:
+       case BTF_KIND_VAR:
                r = btf_dedup_remap_type_id(d, t->type);
                if (r < 0)
                        return r;
@@ -2753,6 +2764,20 @@ static int btf_dedup_remap_type(struct btf_dedup *d, 
__u32 type_id)
                break;
        }
 
+       case BTF_KIND_DATASEC: {
+               struct btf_var_secinfo *var = (struct btf_var_secinfo *)(t + 1);
+               __u16 vlen = BTF_INFO_VLEN(t->info);
+
+               for (i = 0; i < vlen; i++) {
+                       r = btf_dedup_remap_type_id(d, var->type);
+                       if (r < 0)
+                               return r;
+                       var->type = r;
+                       var++;
+               }
+               break;
+       }
+
        default:
                return -EINVAL;
        }
-- 
2.17.1