libbpf: Make use of BTF field iterator in BPF linker code

Switch all BPF linker code dealing with iterating BTF type ID and string
offset fields to new btf_field_iter facilities.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20240605001629.4061937-3-andrii@kernel.org

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 50ff8b6eaf3663bd51e673b826fcfffeb9a72468..d72260ac26a52f8d524eaf40bf92323910ebe8df 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -5267,7 +5267,7 @@ __u32 *btf_field_iter_next(struct btf_field_iter *it)
                return NULL;
 
        if (it->m_idx < 0) {
-               if (it->off_idx < it->desc.t_cnt)
+               if (it->off_idx < it->desc.t_off_cnt)
                        return it->p + it->desc.t_offs[it->off_idx++];
                /* move to per-member iteration */
                it->m_idx = 0;
@@ -5281,7 +5281,7 @@ __u32 *btf_field_iter_next(struct btf_field_iter *it)
                return NULL;
        }
 
-       if (it->off_idx >= it->desc.m_cnt) {
+       if (it->off_idx >= it->desc.m_off_cnt) {
                /* exhausted this member's fields, go to the next member */
                it->m_idx++;
                it->p += it->desc.m_sz;

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 80f3d346db334a62727c18a5f267f4317cf835d3..96c0b0993f8bc674eb798225781dc90238238bd2 100644 (file)
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -515,11 +515,11 @@ enum btf_field_iter_kind {
 
 struct btf_field_desc {
        /* once-per-type offsets */
-       int t_cnt, t_offs[2];
+       int t_off_cnt, t_offs[2];
        /* member struct size, or zero, if no members */
        int m_sz;
        /* repeated per-member offsets */
-       int m_cnt, m_offs[1];
+       int m_off_cnt, m_offs[1];
 };
 
 struct btf_field_iter {

diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 0d4be829551b578c01d1be2049d22a1ea7bb4c9b..fa11a671da3e07e03fce06b712e958b251a0b79d 100644 (file)
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -957,19 +957,33 @@ static int check_btf_str_off(__u32 *str_off, void *ctx)
 static int linker_sanity_check_btf(struct src_obj *obj)
 {
        struct btf_type *t;
-       int i, n, err = 0;
+       int i, n, err;
 
        if (!obj->btf)
                return 0;
 
        n = btf__type_cnt(obj->btf);
        for (i = 1; i < n; i++) {
+               struct btf_field_iter it;
+               __u32 *type_id, *str_off;
+
                t = btf_type_by_id(obj->btf, i);
 
-               err = err ?: btf_type_visit_type_ids(t, check_btf_type_id, obj->btf);
-               err = err ?: btf_type_visit_str_offs(t, check_btf_str_off, obj->btf);
+               err = btf_field_iter_init(&it, t, BTF_FIELD_ITER_IDS);
                if (err)
                        return err;
+               while ((type_id = btf_field_iter_next(&it))) {
+                       if (*type_id >= n)
+                               return -EINVAL;
+               }
+
+               err = btf_field_iter_init(&it, t, BTF_FIELD_ITER_STRS);
+               if (err)
+                       return err;
+               while ((str_off = btf_field_iter_next(&it))) {
+                       if (!btf__str_by_offset(obj->btf, *str_off))
+                               return -EINVAL;
+               }
        }
 
        return 0;
@@ -2234,26 +2248,10 @@ static int linker_fixup_btf(struct src_obj *obj)
        return 0;
 }
 
-static int remap_type_id(__u32 *type_id, void *ctx)
-{
-       int *id_map = ctx;
-       int new_id = id_map[*type_id];
-
-       /* Error out if the type wasn't remapped. Ignore VOID which stays VOID. */
-       if (new_id == 0 && *type_id != 0) {
-               pr_warn("failed to find new ID mapping for original BTF type ID %u\n", *type_id);
-               return -EINVAL;
-       }
-
-       *type_id = id_map[*type_id];
-
-       return 0;
-}
-
 static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
 {
        const struct btf_type *t;
-       int i, j, n, start_id, id;
+       int i, j, n, start_id, id, err;
        const char *name;
 
        if (!obj->btf)
@@ -2324,9 +2322,25 @@ static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
        n = btf__type_cnt(linker->btf);
        for (i = start_id; i < n; i++) {
                struct btf_type *dst_t = btf_type_by_id(linker->btf, i);
+               struct btf_field_iter it;
+               __u32 *type_id;
 
-               if (btf_type_visit_type_ids(dst_t, remap_type_id, obj->btf_type_map))
-                       return -EINVAL;
+               err = btf_field_iter_init(&it, dst_t, BTF_FIELD_ITER_IDS);
+               if (err)
+                       return err;
+
+               while ((type_id = btf_field_iter_next(&it))) {
+                       int new_id = obj->btf_type_map[*type_id];
+
+                       /* Error out if the type wasn't remapped. Ignore VOID which stays VOID. */
+                       if (new_id == 0 && *type_id != 0) {
+                               pr_warn("failed to find new ID mapping for original BTF type ID %u\n",
+                                       *type_id);
+                               return -EINVAL;
+                       }
+
+                       *type_id = obj->btf_type_map[*type_id];
+               }
        }
 
        /* Rewrite VAR/FUNC underlying types (i.e., FUNC's FUNC_PROTO and VAR's