linux-kernel - [tip:locking/core] jump_label: Add a jump_label_can

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Date:   Mon, 17 Jun 2019 07:13:06 -0700
From:   tip-bot for Daniel Bristot de Oliveira <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, rostedt@...dmis.org, williams@...hat.com,
        jkosina@...e.cz, jbaron@...mai.com, swood@...hat.com,
        crecklin@...hat.com, bristot@...hat.com, mhiramat@...nel.org,
        hpa@...or.com, tglx@...utronix.de, gregkh@...uxfoundation.org,
        mtosatti@...hat.com, torvalds@...ux-foundation.org,
        mingo@...nel.org, bp@...en8.de, jpoimboe@...hat.com,
        linux-kernel@...r.kernel.org
Subject: [tip:locking/core] jump_label: Add a jump_label_can_update() helper

Commit-ID:  e1aacb3f4adc1bcd4273a1d538a2dc3e50f1cbb5
Gitweb:     https://git.kernel.org/tip/e1aacb3f4adc1bcd4273a1d538a2dc3e50f1cbb5
Author:     Daniel Bristot de Oliveira <bristot@...hat.com>
AuthorDate: Wed, 12 Jun 2019 11:57:26 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 17 Jun 2019 12:09:19 +0200

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@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Chris von Recklinghausen <crecklin@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Scott Wood <swood@...hat.com>
Cc: Steven Rostedt (VMware) <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/56b69bd3f8e644ed64f2dbde7c088030b8cbe76b.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/jump_label.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0bfa10f4410c..24f0d3b1526b 100644
--- 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));
 	}
 }