module_arch_freeing_init(): new hook for archs before module->module_init freed.

Archs have been abusing module_free() to clean up their arch-specific
allocations.  Since module_free() is also (ab)used by BPF and trace code,
let's keep it to simple allocations, and provide a hook called before
that.

This means that avr32, ia64, parisc and s390 no longer need to implement
their own module_free() at all.  avr32 doesn't need module_finalize()
either.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-s390@vger.kernel.org
diff --git a/kernel/module.c b/kernel/module.c
index 3965511..68be0b1f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1804,6 +1804,10 @@
 {
 }
 
+void __weak module_arch_freeing_init(struct module *mod)
+{
+}
+
 /* Free a module, remove from lists, etc. */
 static void free_module(struct module *mod)
 {
@@ -1841,6 +1845,7 @@
 
 	/* This may be NULL, but that's OK */
 	unset_module_init_ro_nx(mod);
+	module_arch_freeing_init(mod);
 	module_free(mod, mod->module_init);
 	kfree(mod->args);
 	percpu_modfree(mod);
@@ -2930,6 +2935,7 @@
 static void module_deallocate(struct module *mod, struct load_info *info)
 {
 	percpu_modfree(mod);
+	module_arch_freeing_init(mod);
 	module_free(mod, mod->module_init);
 	module_free(mod, mod->module_core);
 }
@@ -3055,6 +3061,7 @@
 	mod->strtab = mod->core_strtab;
 #endif
 	unset_module_init_ro_nx(mod);
+	module_arch_freeing_init(mod);
 	module_free(mod, mod->module_init);
 	mod->module_init = NULL;
 	mod->init_size = 0;