[RFC bpf-next 10/13] module, bpf: store BTF base reference pointer in struct module

[Alan Maguire <alan.maguire@oracle.com>]

...as this will allow split BTF modules with a base reference BTF
representation (rather than the full vmlinux BTF at time of
BTF encoding) to resolve their references to kernel types in a
way that is more resilient to small changes in kernel types.

This will allow modules that are not built every time the kernel
is to provide more resilient BTF, rather than have it invalidated
every time BTF ids for core kernel types change.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 include/linux/module.h | 2 ++
 kernel/module/main.c   | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/module.h b/include/linux/module.h
index 1153b0d99a80..4167175b580b 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -510,6 +510,8 @@ struct module {
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	unsigned int btf_data_size;
 	void *btf_data;
+	unsigned int btf_base_ref_data_size;
+	void *btf_base_ref_data;
 #endif
 #ifdef CONFIG_JUMP_LABEL
 	struct jump_entry *jump_entries;
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 36681911c05a..d116ca4a5794 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2148,6 +2148,8 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 #endif
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size);
+	mod->btf_base_ref_data = any_section_objs(info, ".BTF.base_ref", 1,
+						  &mod->btf_base_ref_data_size);
 #endif
 #ifdef CONFIG_JUMP_LABEL
 	mod->jump_entries = section_objs(info, "__jump_table",
-- 
2.39.3