Commit 698bacef authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

static_call: Align static_call_is_init() patching condition 



The intent is to avoid writing init code after init (because the text
might have been freed). The code is needlessly different between
jump_label and static_call and not obviously correct.

The existing code relies on the fact that the module loader clears the
init layout, such that within_module_init() always fails, while
jump_label relies on the module state which is more obvious and
matches the kernel logic.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Tested-by: default avatarSumit Garg <sumit.garg@linaro.org>
Link: https://lkml.kernel.org/r/20210318113610.636651340@infradead.org
parent 68b1eddd

kernel/static_call.c

+4 −10
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) 
	};



	for (site_mod = &first; site_mod; site_mod = site_mod->next) {

		bool init = system_state < SYSTEM_RUNNING;

		struct module *mod = site_mod->mod;



		if (!site_mod->sites) {
@@ -168,6 +169,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) 
		if (mod) {

			stop = mod->static_call_sites +

			       mod->num_static_call_sites;

			init = mod->state == MODULE_STATE_COMING;

		}

#endif
@@ -175,16 +177,8 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) 
		     site < stop && static_call_key(site) == key; site++) {

			void *site_addr = static_call_addr(site);



			if (static_call_is_init(site)) {

				/*

				 * Don't write to call sites which were in

				 * initmem and have since been freed.

				 */

				if (!mod && system_state >= SYSTEM_RUNNING)

			if (!init && static_call_is_init(site))

				continue;

				if (mod && !within_module_init((unsigned long)site_addr, mod))

					continue;

			}



			if (!kernel_text_address((unsigned long)site_addr)) {

				WARN_ONCE(1, "can't patch static call site at %pS",