[tip:x86/alternatives] jump_label: Add the jump_label_can_update_check() helper

[tip-bot for Daniel Bristot de Oliveira]

Commit-ID:  41bef31d0abe29b5888b33b526cacc8a30795318
Gitweb:     https://git.kernel.org/tip/41bef31d0abe29b5888b33b526cacc8a30795318
Author:     Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
AuthorDate: Fri, 21 Dec 2018 11:27:27 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 19 Apr 2019 19:37:34 +0200

jump_label: Add the jump_label_can_update_check() helper

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

Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Chris von Recklinghausen <crecklin@xxxxxxxxxx>
Cc: Clark Williams <williams@xxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Scott Wood <swood@xxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1e758cd3b2206be96091a57a17b26585e94792b6.1545228276.git.bristot@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/jump_label.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 288d630da22d..456c0d7cbb5b 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -374,22 +374,32 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry)
 	return enabled ^ branch;
 }
 
+bool jump_label_can_update_check(struct jump_entry *entry, bool init)
+{
+	/*
+	 * 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))) {
+			WARN_ONCE(1, "can't patch jump_label at %pS",
+				  (void *)jump_entry_code(entry));
+			return 0;
+		}
+		return 1;
+	}
+	return 0;
+}
+
 static void __jump_label_update(struct static_key *key,
 				struct jump_entry *entry,
 				struct jump_entry *stop,
 				bool init)
 {
 	for_each_label_entry(key, entry, stop) {
-		/*
-		 * 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_check(entry, init)) {
+			arch_jump_label_transform(entry,
+						  jump_label_type(entry));
 		}
 	}
 }