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

Showing the changes to kernel/module (1 of 2 files). Show all

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kernel/module/main.c+4−1

@@ -2166,6 +2166,8 @@ static int find_module_sections(struct module mod, struct load_info info) · 2165 unmodified lines
2166	2166	#endif
2167	2167	#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
2168	2168	mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size);
	2169	+ mod->btf_base_data = any_section_objs(info, ".BTF.base", 1,
	2170	+ &mod->btf_base_data_size);
2169	2171	#endif
2170	2172	#ifdef CONFIG_JUMP_LABEL
2171	2173	mod->jump_entries = section_objs(info, "__jump_table",
@@ -2590,8 +2592,9 @@ static noinline int do_init_module(struct module *mod) · 418 unmodified lines
2590	2592	}
2591	2593
2592	2594	#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
2593		− /* .BTF is not SHF_ALLOC and will get removed, so sanitize pointer */
	2595	+ /* .BTF is not SHF_ALLOC and will get removed, so sanitize pointers */
2594	2596	mod->btf_data = NULL;
	2597	+ mod->btf_base_data = NULL;
2595	2598	#endif
2596	2599	/*
2597	2600	* We want to free module_init, but be aware that kallsyms may be