On Tue, 29 Mar 2016, Jiri Kosina wrote:
> Agreed; I think we should be safe applying all the alternatives (with
> paravirt being really just a special case of those) to the coming module
> at the very last phase; they really are required only during runtime,
> but nothing else should be depending on them. Right? If anyone is able
> to come up with and counter-example, please speak up :)
So I have quickly gone through all the architectures that actually do
overload __weak module_finalize() by their own implementation, and except
for applying self-modifying code changes and registering unwind tables,
there doesn't seem to be any relevant heavy-lifting, that'd need to be
done before relocations have been written.
Is the (completely untested) sort-of-a-patch below a complete rubbish
(on top of current livepatching.git's for-next)?
diff --git a/kernel/module.c b/kernel/module.c
index 5f71aa6..c003648 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3211,7 +3211,7 @@ int __weak module_finalize(const Elf_Ehdr *hdr,
return 0;
}
-static int post_relocation(struct module *mod, const struct load_info *info)
+static void post_relocation(struct module *mod, const struct load_info *info)
{
/* Sort exception table now relocations are done. */
sort_extable(mod->extable, mod->extable + mod->num_exentries);
@@ -3222,9 +3222,6 @@ static int post_relocation(struct module *mod, const struct load_info *info)
/* Setup kallsyms-specific fields. */
add_kallsyms(mod, info);
-
- /* Arch-specific module finalizing. */
- return module_finalize(info->hdr, info->sechdrs, mod);
}
/* Is this module of this name done loading? No locks held. */
@@ -3562,9 +3559,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err < 0)
goto free_modinfo;
- err = post_relocation(mod, info);
- if (err < 0)
- goto free_modinfo;
+ post_relocation(mod, info);
flush_module_icache(mod);
@@ -3589,6 +3584,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err)
goto bug_cleanup;
+ /* Arch-specific module finalizing. */
+ err = module_finalize(info->hdr, info->sechdrs, mod);
+ if (err)
+ goto bug_cleanup;
+
/* Module is ready to execute: parsing args may do that. */
after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
-32768, 32767, mod,
--
Jiri Kosina
SUSE Labs
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