static_call: Fix static_call_set_init()

It turns out that static_call_set_init() does not preserve the other
flags; IOW. it clears TAIL if it was set.

Fixes: 9183c3f9ed710 ("static_call: Add inline static call infrastructure")
Reported-by: Sumit Garg <sumit.garg@linaro.org>
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/20210318113610.519406371@infradead.org

diff --git a/kernel/static_call.c b/kernel/static_call.c
index ae82529..080c8a9 100644 (file)
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -35,27 +35,30 @@ static inline void *static_call_addr(struct static_call_site *site)
        return (void *)((long)site->addr + (long)&site->addr);
 }
 
+static inline unsigned long __static_call_key(const struct static_call_site *site)
+{
+       return (long)site->key + (long)&site->key;
+}
 
 static inline struct static_call_key *static_call_key(const struct static_call_site *site)
 {
-       return (struct static_call_key *)
-               (((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS);
+       return (void *)(__static_call_key(site) & ~STATIC_CALL_SITE_FLAGS);
 }
 
 /* These assume the key is word-aligned. */
 static inline bool static_call_is_init(struct static_call_site *site)
 {
-       return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT;
+       return __static_call_key(site) & STATIC_CALL_SITE_INIT;
 }
 
 static inline bool static_call_is_tail(struct static_call_site *site)
 {
-       return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL;
+       return __static_call_key(site) & STATIC_CALL_SITE_TAIL;
 }
 
 static inline void static_call_set_init(struct static_call_site *site)
 {
-       site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) -
+       site->key = (__static_call_key(site) | STATIC_CALL_SITE_INIT) -
                    (long)&site->key;
 }
 
@@ -190,7 +193,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
                        }
 
                        arch_static_call_transform(site_addr, NULL, func,
-                               static_call_is_tail(site));
+                                                  static_call_is_tail(site));
                }
        }
 
@@ -349,7 +352,7 @@ static int static_call_add_module(struct module *mod)
        struct static_call_site *site;
 
        for (site = start; site != stop; site++) {
-               unsigned long s_key = (long)site->key + (long)&site->key;
+               unsigned long s_key = __static_call_key(site);
                unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS;
                unsigned long key;