On Tue, Jun 18, 2024 at 9:25 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> ...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.
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> ---
> include/linux/module.h | 2 ++
> kernel/module/main.c | 5 ++++-
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index ffa1c603163c..b79d926cae8a 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -509,7 +509,9 @@ struct module {
> #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;
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index d18a94b973e1..d9592195c5bb 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2166,6 +2166,8 @@ 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_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",
> @@ -2590,8 +2592,9 @@ static noinline int do_init_module(struct module *mod)
> }
>
> #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
> --
> 2.31.1
>
