netdev - [PATCH bpf-next v5 1/9] libbpf: Implement changes needed for BTFGen in bpftool

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Date:   Fri, 28 Jan 2022 17:33:04 -0500
From:   Mauricio Vásquez <mauricio@...volk.io>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Quentin Monnet <quentin@...valent.com>,
        Rafael David Tinoco <rafaeldtinoco@...il.com>,
        Lorenzo Fontana <lorenzo.fontana@...stic.co>,
        Leonardo Di Donato <leonardo.didonato@...stic.co>
Subject: [PATCH bpf-next v5 1/9] libbpf: Implement changes needed for BTFGen in bpftool

This commit extends libbpf with the features that are needed to
implement BTFGen:

- Implement bpf_core_create_cand_cache() and bpf_core_free_cand_cache()
to handle candidates cache.
- Expose bpf_core_add_cands() and bpf_core_free_cands to handle
candidates list.
- Expose bpf_core_calc_relo_insn() to bpftool.

Signed-off-by: Mauricio Vásquez <mauricio@...volk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@...asec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@...stic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@...stic.co>
---
 tools/lib/bpf/libbpf.c          | 44 ++++++++++++++++++++++-----------
 tools/lib/bpf/libbpf_internal.h | 12 +++++++++
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 12771f71a6e7..61384d219e28 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5195,18 +5195,18 @@ size_t bpf_core_essential_name_len(const char *name)
 	return n;
 }
 
-static void bpf_core_free_cands(struct bpf_core_cand_list *cands)
+void bpf_core_free_cands(struct bpf_core_cand_list *cands)
 {
 	free(cands->cands);
 	free(cands);
 }
 
-static int bpf_core_add_cands(struct bpf_core_cand *local_cand,
-			      size_t local_essent_len,
-			      const struct btf *targ_btf,
-			      const char *targ_btf_name,
-			      int targ_start_id,
-			      struct bpf_core_cand_list *cands)
+int bpf_core_add_cands(struct bpf_core_cand *local_cand,
+		       size_t local_essent_len,
+		       const struct btf *targ_btf,
+		       const char *targ_btf_name,
+		       int targ_start_id,
+		       struct bpf_core_cand_list *cands)
 {
 	struct bpf_core_cand *new_cands, *cand;
 	const struct btf_type *t, *local_t;
@@ -5577,6 +5577,25 @@ static int bpf_core_resolve_relo(struct bpf_program *prog,
 				       targ_res);
 }
 
+struct hashmap *bpf_core_create_cand_cache(void)
+{
+	return hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
+}
+
+void bpf_core_free_cand_cache(struct hashmap *cand_cache)
+{
+	struct hashmap_entry *entry;
+	int i;
+
+	if (IS_ERR_OR_NULL(cand_cache))
+		return;
+
+	hashmap__for_each_entry(cand_cache, entry, i) {
+		bpf_core_free_cands(entry->value);
+	}
+	hashmap__free(cand_cache);
+}
+
 static int
 bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 {
@@ -5584,7 +5603,6 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 	struct bpf_core_relo_res targ_res;
 	const struct bpf_core_relo *rec;
 	const struct btf_ext_info *seg;
-	struct hashmap_entry *entry;
 	struct hashmap *cand_cache = NULL;
 	struct bpf_program *prog;
 	struct bpf_insn *insn;
@@ -5603,7 +5621,7 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 		}
 	}
 
-	cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
+	cand_cache = bpf_core_create_cand_cache();
 	if (IS_ERR(cand_cache)) {
 		err = PTR_ERR(cand_cache);
 		goto out;
@@ -5694,12 +5712,8 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 	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);
-		}
-		hashmap__free(cand_cache);
-	}
+	bpf_core_free_cand_cache(cand_cache);
+
 	return err;
 }
 
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index bc86b82e90d1..686a5654262b 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -529,4 +529,16 @@ static inline int ensure_good_fd(int fd)
 	return fd;
 }
 
+struct hashmap;
+
+struct hashmap *bpf_core_create_cand_cache(void);
+void bpf_core_free_cand_cache(struct hashmap *cand_cache);
+int bpf_core_add_cands(struct bpf_core_cand *local_cand,
+		       size_t local_essent_len,
+		       const struct btf *targ_btf,
+		       const char *targ_btf_name,
+		       int targ_start_id,
+		       struct bpf_core_cand_list *cands);
+void bpf_core_free_cands(struct bpf_core_cand_list *cands);
+
 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
-- 
2.25.1