On Mon, 9 Nov 2015, Jessica Yu wrote:
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 3a19c79..c8680b1 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
[...]
> +#ifdef CONFIG_LIVEPATCH
> +extern void klp_prepare_patch_module(struct module *mod,
> + struct load_info *info);
> +extern int
> +apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
> + unsigned int symindex, unsigned int relsec,
> + struct module *me);
> +#endif
> +
> #else /* !CONFIG_MODULES... */
apply_relocate_add() is already in include/linux/moduleloader.h (guarded
by CONFIG_MODULES_USE_ELF_RELA), so maybe we can just include that where
we need it. As for the klp_prepare_patch_module() wouldn't it be better to
have it in our livepatch.h and include that in kernel/module.c?
> /* Given an address, look for it in the exception tables. */
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 6e53441..087a8c7 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -1001,6 +1001,23 @@ static struct notifier_block klp_module_nb = {
> .priority = INT_MIN+1, /* called late but before ftrace notifier */
> };
>
> +/*
> + * Save necessary information from info in order to be able to
> + * patch modules that might be loaded later
> + */
> +void klp_prepare_patch_module(struct module *mod, struct load_info *info)
> +{
> + Elf_Shdr *symsect;
> +
> + symsect = info->sechdrs + info->index.sym;
> + /* update sh_addr to point to symtab */
> + symsect->sh_addr = (unsigned long)info->hdr + symsect->sh_offset;
> +
> + mod->info = kzalloc(sizeof(*info), GFP_KERNEL);
> + memcpy(mod->info, info, sizeof(*info));
> +
> +}
What about arch-specific 'struct mod_arch_specific'? We need to preserve
it somewhere as well for s390x and other non-x86 architectures.
> +#ifdef CONFIG_LIVEPATCH
> + /*
> + * Save sechdrs, indices, and other data from info
> + * in order to patch to-be-loaded modules.
> + * Do not call free_copy() for livepatch modules.
> + */
> + if (get_modinfo((struct load_info *)info, "livepatch"))
> + klp_prepare_patch_module(mod, info);
> + else
> + free_copy(info);
> +#else
> /* Get rid of temporary copy. */
> free_copy(info);
> +#endif
Maybe I am missing something but isn't it necessary to call vfree() on
info somewhere in the end?
Regards,
Miroslav
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