Refactor CO-RE relocation candidate search to not expect a single BTF, rather
return all candidate types with their corresponding BTF objects. This will
allow to extend CO-RE relocations to accommodate kernel module BTFs.
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 187 ++++++++++++++++++++++++-----------------
1 file changed, 111 insertions(+), 76 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 313034117070..c4a49e8eb7b5 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -462,11 +462,14 @@ struct bpf_object {
struct list_head list;
struct btf *btf;
+ struct btf_ext *btf_ext;
+
/* Parse and load BTF vmlinux if any of the programs in the object need
* it at load time.
*/
struct btf *btf_vmlinux;
- struct btf_ext *btf_ext;
+ /* vmlinux BTF override for CO-RE relocations */
+ struct btf *btf_vmlinux_override;
void *priv;
bpf_object_clear_priv_t clear_priv;
@@ -4600,46 +4603,43 @@ static size_t bpf_core_essential_name_len(const char *name)
return n;
}
-/* dynamically sized list of type IDs */
-struct ids_vec {
- __u32 *data;
+struct core_cand
+{
+ const struct btf *btf;
+ const struct btf_type *t;
+ const char *name;
+ __u32 id;
+};
+
+/* dynamically sized list of type IDs and its associated struct btf */
+struct core_cand_list {
+ struct core_cand *cands;
int len;
};
-static void bpf_core_free_cands(struct ids_vec *cand_ids)
+static void bpf_core_free_cands(struct core_cand_list *cands)
{
- free(cand_ids->data);
- free(cand_ids);
+ free(cands->cands);
+ free(cands);
}
-static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
- __u32 local_type_id,
- const struct btf *targ_btf)
+static int bpf_core_add_cands(struct core_cand *local_cand,
+ size_t local_essent_len,
+ const struct btf *targ_btf,
+ const char *targ_btf_name,
+ int targ_start_id,
+ struct core_cand_list *cands)
{
- size_t local_essent_len, targ_essent_len;
- const char *local_name, *targ_name;
- const struct btf_type *t, *local_t;
- struct ids_vec *cand_ids;
- __u32 *new_ids;
- int i, err, n;
-
- local_t = btf__type_by_id(local_btf, local_type_id);
- if (!local_t)
- return ERR_PTR(-EINVAL);
-
- local_name = btf__name_by_offset(local_btf, local_t->name_off);
- if (str_is_empty(local_name))
- return ERR_PTR(-EINVAL);
- local_essent_len = bpf_core_essential_name_len(local_name);
-
- cand_ids = calloc(1, sizeof(*cand_ids));
- if (!cand_ids)
- return ERR_PTR(-ENOMEM);
+ struct core_cand *new_cands, *cand;
+ const struct btf_type *t;
+ const char *targ_name;
+ size_t targ_essent_len;
+ int n, i;
n = btf__get_nr_types(targ_btf);
- for (i = 1; i <= n; i++) {
+ for (i = targ_start_id; i <= n; i++) {
t = btf__type_by_id(targ_btf, i);
- if (btf_kind(t) != btf_kind(local_t))
+ if (btf_kind(t) != btf_kind(local_cand->t))
continue;
targ_name = btf__name_by_offset(targ_btf, t->name_off);
@@ -4650,25 +4650,62 @@ static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
if (targ_essent_len != local_essent_len)
continue;
- if (strncmp(local_name, targ_name, local_essent_len) == 0) {
- pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s\n",
- local_type_id, btf_kind_str(local_t),
- local_name, i, btf_kind_str(t), targ_name);
- new_ids = libbpf_reallocarray(cand_ids->data,
- cand_ids->len + 1,
- sizeof(*cand_ids->data));
- if (!new_ids) {
- err = -ENOMEM;
- goto err_out;
- }
- cand_ids->data = new_ids;
- cand_ids->data[cand_ids->len++] = i;
- }
+ if (strncmp(local_cand->name, targ_name, local_essent_len) != 0)
+ continue;
+
+ pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
+ local_cand->id, btf_kind_str(local_cand->t),
+ local_cand->name, i, btf_kind_str(t), targ_name,
+ targ_btf_name);
+ new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
+ sizeof(*cands->cands));
+ if (!new_cands)
+ return -ENOMEM;
+
+ cand = &new_cands[cands->len];
+ cand->btf = targ_btf;
+ cand->t = t;
+ cand->name = targ_name;
+ cand->id = i;
+
+ cands->cands = new_cands;
+ cands->len++;
}
- return cand_ids;
-err_out:
- bpf_core_free_cands(cand_ids);
- return ERR_PTR(err);
+ return 0;
+}
+
+static struct core_cand_list *
+bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
+{
+ struct core_cand local_cand = {};
+ struct core_cand_list *cands;
+ size_t local_essent_len;
+ int err;
+
+ local_cand.btf = local_btf;
+ local_cand.t = btf__type_by_id(local_btf, local_type_id);
+ if (!local_cand.t)
+ return ERR_PTR(-EINVAL);
+
+ local_cand.name = btf__name_by_offset(local_btf, local_cand.t->name_off);
+ if (str_is_empty(local_cand.name))
+ return ERR_PTR(-EINVAL);
+ local_essent_len = bpf_core_essential_name_len(local_cand.name);
+
+ cands = calloc(1, sizeof(*cands));
+ if (!cands)
+ return ERR_PTR(-ENOMEM);
+
+ /* Attempt to find target candidates in vmlinux BTF first */
+ err = bpf_core_add_cands(&local_cand, local_essent_len,
+ obj->btf_vmlinux_override ?: obj->btf_vmlinux,
+ "vmlinux", 1, cands);
+ if (err) {
+ bpf_core_free_cands(cands);
+ return ERR_PTR(err);
+ }
+
+ return cands;
}
/* Check two types for compatibility for the purpose of field access
@@ -5661,7 +5698,6 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
- const struct btf *targ_btf,
struct hashmap *cand_cache)
{
struct bpf_core_spec local_spec, cand_spec, targ_spec = {};
@@ -5669,8 +5705,8 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
struct bpf_core_relo_res cand_res, targ_res;
const struct btf_type *local_type;
const char *local_name;
- struct ids_vec *cand_ids;
- __u32 local_id, cand_id;
+ struct core_cand_list *cands = NULL;
+ __u32 local_id;
const char *spec_str;
int i, j, err;
@@ -5717,24 +5753,24 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
return -EOPNOTSUPP;
}
- if (!hashmap__find(cand_cache, type_key, (void **)&cand_ids)) {
- cand_ids = bpf_core_find_cands(local_btf, local_id, targ_btf);
- if (IS_ERR(cand_ids)) {
+ if (!hashmap__find(cand_cache, type_key, (void **)&cands)) {
+ cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
+ if (IS_ERR(cands)) {
pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld",
prog->name, relo_idx, local_id, btf_kind_str(local_type),
- local_name, PTR_ERR(cand_ids));
- return PTR_ERR(cand_ids);
+ local_name, PTR_ERR(cands));
+ return PTR_ERR(cands);
}
- err = hashmap__set(cand_cache, type_key, cand_ids, NULL, NULL);
+ err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
if (err) {
- bpf_core_free_cands(cand_ids);
+ bpf_core_free_cands(cands);
return err;
}
}
- for (i = 0, j = 0; i < cand_ids->len; i++) {
- cand_id = cand_ids->data[i];
- err = bpf_core_spec_match(&local_spec, targ_btf, cand_id, &cand_spec);
+ for (i = 0, j = 0; i < cands->len; i++) {
+ err = bpf_core_spec_match(&local_spec, cands->cands[i].btf,
+ cands->cands[i].id, &cand_spec);
if (err < 0) {
pr_warn("prog '%s': relo #%d: error matching candidate #%d ",
prog->name, relo_idx, i);
@@ -5778,7 +5814,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
return -EINVAL;
}
- cand_ids->data[j++] = cand_spec.root_type_id;
+ cands->cands[j++] = cands->cands[i];
}
/*
@@ -5790,7 +5826,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
* depending on relo's kind.
*/
if (j > 0)
- cand_ids->len = j;
+ cands->len = j;
/*
* If no candidates were found, it might be both a programmer error,
@@ -5834,20 +5870,19 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
struct hashmap_entry *entry;
struct hashmap *cand_cache = NULL;
struct bpf_program *prog;
- struct btf *targ_btf;
const char *sec_name;
int i, err = 0, insn_idx, sec_idx;
if (obj->btf_ext->core_relo_info.len == 0)
return 0;
- if (targ_btf_path)
- targ_btf = btf__parse(targ_btf_path, NULL);
- else
- targ_btf = obj->btf_vmlinux;
- if (IS_ERR_OR_NULL(targ_btf)) {
- pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
- return PTR_ERR(targ_btf);
+ if (targ_btf_path) {
+ obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
+ if (IS_ERR_OR_NULL(obj->btf_vmlinux_override)) {
+ err = PTR_ERR(obj->btf_vmlinux_override);
+ pr_warn("failed to parse target BTF: %d\n", err);
+ return err;
+ }
}
cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
@@ -5899,8 +5934,7 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
if (!prog->load)
continue;
- err = bpf_core_apply_relo(prog, rec, i, obj->btf,
- targ_btf, cand_cache);
+ err = bpf_core_apply_relo(prog, rec, i, obj->btf, cand_cache);
if (err) {
pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
prog->name, i, err);
@@ -5911,8 +5945,9 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
out:
/* obj->btf_vmlinux is freed at the end of object load phase */
- if (targ_btf != obj->btf_vmlinux)
- btf__free(targ_btf);
+ btf__free(obj->btf_vmlinux_override);
+ obj->btf_vmlinux_override = NULL;
+
if (!IS_ERR_OR_NULL(cand_cache)) {
hashmap__for_each_entry(cand_cache, entry, i) {
bpf_core_free_cands(entry->value);
--
2.24.1
