module, bpf: Store BTF base pointer in struct module

...as this will allow split BTF modules with a base 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. Fields are ordered to avoid holes in struct module.

Alan Maguire committed 2 years ago

Commit d4e48e31 parent d1cf8402 files · +6 −1Browse files

Unified · Split

2 files

include/linux/module.h +2 −0
kernel/module/main.c +4 −1

include/linux/module.h+2−0

 #endif
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	unsigned int btf_data_size;
+	unsigned int btf_base_data_size;
 	void *btf_data;
+	void *btf_base_data;
 #endif
 #ifdef CONFIG_JUMP_LABEL
 	struct jump_entry *jump_entries;

kernel/module/main.c+4−1

 #endif
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size);
+	mod->btf_base_data = any_section_objs(info, ".BTF.base", 1,
+					      &mod->btf_base_data_size);
 #endif
 #ifdef CONFIG_JUMP_LABEL
 	mod->jump_entries = section_objs(info, "__jump_table",
 	}
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
-	/* .BTF is not SHF_ALLOC and will get removed, so sanitize pointer */
+	/* .BTF is not SHF_ALLOC and will get removed, so sanitize pointers */
 	mod->btf_data = NULL;
+	mod->btf_base_data = NULL;
 #endif
 	/*
 	 * We want to free module_init, but be aware that kallsyms may be