linux-kernel - [RFC PATCH 2/6] jump_label: Add the jump_label_can_update

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Message-Id: <6323276163587de071cd830f9f4def97cf222550.1539001620.git.bristot@redhat.com>
Date:   Mon,  8 Oct 2018 14:53:01 +0200
From:   Daniel Bristot de Oliveira <bristot@...hat.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Zhou Chengming <zhouchengming1@...wei.com>,
        Jiri Kosina <jkosina@...e.cz>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Chris von Recklinghausen <crecklin@...hat.com>,
        Jason Baron <jbaron@...mai.com>, Scott Wood <swood@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Clark Williams <williams@...hat.com>
Subject: [RFC PATCH 2/6] jump_label: Add the jump_label_can_update_check() helper

Move the check of if a jump_entry is valid to a function.

Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Pavel Tatashin <pasha.tatashin@...cle.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc: Zhou Chengming <zhouchengming1@...wei.com>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>
Cc: Chris von Recklinghausen <crecklin@...hat.com>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Scott Wood <swood@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.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 e853916a3b46..940ba7819c87 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -361,22 +361,29 @@ 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)
+{
+	/*
+	 * An entry->code of 0 indicates an entry which has been
+	 * disabled because it was in an init text area.
+	 */
+	if (entry->code) {
+		if (kernel_text_address(entry->code))
+			return 1;
+		else
+			WARN_ONCE(1, "can't patch jump_label at %pS",
+				  (void *)(unsigned long)entry->code);
+	}
+	return 0;
+}
+
 static void __jump_label_update(struct static_key *key,
 				struct jump_entry *entry,
 				struct jump_entry *stop)
 {
 	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 (entry->code) {
-			if (kernel_text_address(entry->code))
-				arch_jump_label_transform(entry, jump_label_type(entry));
-			else
-				WARN_ONCE(1, "can't patch jump_label at %pS",
-					  (void *)(unsigned long)entry->code);
-		}
+		if (jump_label_can_update_check(entry))
+			arch_jump_label_transform(entry, jump_label_type(entry));
 	}
 }
 
-- 
2.17.1