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: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lkml.kernel.org/r/20210318113610.636651340@infradead.org

diff --git a/kernel/static_call.c b/kernel/static_call.c
index 080c8a9ddfafb817322c30a0bd3b2023d0d8d40a..fc2259047be21058ea05e337e420637317ddca5d 100644 (file)
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -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)
-                                       continue;
-                               if (mod && !within_module_init((unsigned long)site_addr, mod))
-                                       continue;
-                       }
+                       if (!init && static_call_is_init(site))
+                               continue;
 
                        if (!kernel_text_address((unsigned long)site_addr)) {
                                WARN_ONCE(1, "can't patch static call site at %pS",