jump_label: Add a jump_label_can_update() helper

Move the check if a jump_entry is valid to a function. No functional
change.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/56b69bd3f8e644ed64f2dbde7c088030b8cbe76b.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0bfa10f4410c5d80049b94126ed97dab1b19010a..24f0d3b1526b115dbec8a383916ff9e3b68b130e 100644 (file)
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -384,23 +384,30 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry)
        return enabled ^ branch;
 }
 
+static bool jump_label_can_update(struct jump_entry *entry, bool init)
+{
+       /*
+        * Cannot update code that was in an init text area.
+        */
+       if (!init && jump_entry_is_init(entry))
+               return false;
+
+       if (!kernel_text_address(jump_entry_code(entry))) {
+               WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry));
+               return false;
+       }
+
+       return true;
+}
+
 static void __jump_label_update(struct static_key *key,
                                struct jump_entry *entry,
                                struct jump_entry *stop,
                                bool init)
 {
        for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
-               /*
-                * An entry->code of 0 indicates an entry which has been
-                * disabled because it was in an init text area.
-                */
-               if (init || !jump_entry_is_init(entry)) {
-                       if (kernel_text_address(jump_entry_code(entry)))
-                               arch_jump_label_transform(entry, jump_label_type(entry));
-                       else
-                               WARN_ONCE(1, "can't patch jump_label at %pS",
-                                         (void *)jump_entry_code(entry));
-               }
+               if (jump_label_can_update(entry, init))
+                       arch_jump_label_transform(entry, jump_label_type(entry));
        }
 }