[PATCH RFC bpf-next 2/9] bpf: export btf functions for modules

[Jesper Dangaard Brouer <brouer@xxxxxxxxxx>]

This allows modules to lookup their own module BTF info.

These are get and set operations that bump the refcount.
Thus, modules can use this to control the lifetime.

Suggested-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
 include/linux/btf.h |    2 ++
 kernel/bpf/btf.c    |   13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 1bfed7fa0428..df9776018059 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -126,6 +126,8 @@ u32 btf_obj_id(const struct btf *btf);
 bool btf_is_kernel(const struct btf *btf);
 bool btf_is_module(const struct btf *btf);
 struct module *btf_try_get_module(const struct btf *btf);
+struct btf *btf_get_module_btf(const struct module *module);
+void btf_put_module_btf(struct btf *btf);
 u32 btf_nr_types(const struct btf *btf);
 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
 			   const struct btf_member *m,
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 2e2066d6af94..96fd5e469b42 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -534,6 +534,7 @@ s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
 
 	return -ENOENT;
 }
+EXPORT_SYMBOL_GPL(btf_find_by_name_kind);
 
 static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
 {
@@ -1674,6 +1675,15 @@ void btf_put(struct btf *btf)
 	}
 }
 
+void btf_put_module_btf(struct btf *btf)
+{
+	if (!btf_is_module(btf))
+		return;
+
+	btf_put(btf);
+}
+EXPORT_SYMBOL_GPL(btf_put_module_btf);
+
 static int env_resolve_init(struct btf_verifier_env *env)
 {
 	struct btf *btf = env->btf;
@@ -7022,7 +7032,7 @@ struct module *btf_try_get_module(const struct btf *btf)
 /* Returns struct btf corresponding to the struct module.
  * This function can return NULL or ERR_PTR.
  */
-static struct btf *btf_get_module_btf(const struct module *module)
+struct btf *btf_get_module_btf(const struct module *module)
 {
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	struct btf_module *btf_mod, *tmp;
@@ -7051,6 +7061,7 @@ static struct btf *btf_get_module_btf(const struct module *module)
 
 	return btf;
 }
+EXPORT_SYMBOL_GPL(btf_get_module_btf);
 
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {