[PATCH v1 bpf-next 02/18] bpf: Add a btf_id_set8_entry helper

[Anton Protopopov]

The pairs of a struct btf_id_set8 have an anonymous type, and the
btf_id_set8_contains() helper returns a void pointer to the pair it
finds. All its users but one only check if a set contains an ID. The
one which needs the flags, btf_kfunc_id_set_contains(), finds them as
the word next to the ID.

Name the type struct btf_id_set8_pair, and add a btf_id_set8_entry()
helper which returns a pointer to it. Make btf_id_set8_contains()
return bool, like btf_id_set_contains() does, and use the new helper
in btf_kfunc_id_set_contains().

The layout of the set doesn't change. Update the tools copy of
btf_ids.h as well. A later patch uses the new helper to set the flags
of a pair.

Signed-off-by: Anton Protopopov <a.s.protopopov@xxxxxxxxx>
---
 include/linux/btf.h           |  8 +++++++-
 include/linux/btf_ids.h       | 10 ++++++----
 kernel/bpf/btf.c              |  9 ++++-----
 tools/include/linux/btf_ids.h | 10 ++++++----
 4 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 87fad4076f0e..00495e7833b6 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -558,11 +558,17 @@ static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
 	return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
 }
 
-static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
+static inline struct btf_id_set8_pair *
+btf_id_set8_entry(const struct btf_id_set8 *set, u32 id)
 {
 	return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
 }
 
+static inline bool btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
+{
+	return btf_id_set8_entry(set, id) != NULL;
+}
+
 bool btf_param_match_suffix(const struct btf *btf,
 			    const struct btf_param *arg,
 			    const char *suffix);
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index f27b7db81100..f5985acf661b 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -19,13 +19,15 @@ struct btf_id_set {
  */
 #define BTF_SET8_FMODRET	(1 << 1)
 
+struct btf_id_set8_pair {
+	u32 id;
+	u32 flags;
+};
+
 struct btf_id_set8 {
 	u32 cnt;
 	u32 flags;
-	struct {
-		u32 id;
-		u32 flags;
-	} pairs[];
+	struct btf_id_set8_pair pairs[];
 };
 
 #ifdef CONFIG_DEBUG_INFO_BTF
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 228b93d4f8c9..61d2df6776a9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -9973,8 +9973,8 @@ static u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 				      enum btf_kfunc_hook hook,
 				      u32 kfunc_btf_id)
 {
+	struct btf_id_set8_pair *pair;
 	struct btf_id_set8 *set;
-	u32 *id;
 
 	if (hook >= BTF_KFUNC_HOOK_MAX)
 		return NULL;
@@ -9983,11 +9983,10 @@ static u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 	set = btf->kfunc_set_tab->sets[hook];
 	if (!set)
 		return NULL;
-	id = btf_id_set8_contains(set, kfunc_btf_id);
-	if (!id)
+	pair = btf_id_set8_entry(set, kfunc_btf_id);
+	if (!pair)
 		return NULL;
-	/* The flags for BTF ID are located next to it */
-	return id + 1;
+	return &pair->flags;
 }
 
 static bool __btf_kfunc_is_allowed(const struct btf *btf,
diff --git a/tools/include/linux/btf_ids.h b/tools/include/linux/btf_ids.h
index b371ef7241b9..3b5b2856c628 100644
--- a/tools/include/linux/btf_ids.h
+++ b/tools/include/linux/btf_ids.h
@@ -19,13 +19,15 @@ struct btf_id_set {
  */
 #define BTF_SET8_FMODRET	(1 << 1)
 
+struct btf_id_set8_pair {
+	u32 id;
+	u32 flags;
+};
+
 struct btf_id_set8 {
 	u32 cnt;
 	u32 flags;
-	struct {
-		u32 id;
-		u32 flags;
-	} pairs[];
+	struct btf_id_set8_pair pairs[];
 };
 
 #ifdef CONFIG_DEBUG_INFO_BTF
-- 
2.43.0