From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 27 Jul 2015 16:32:09 +0000 (+0200)
Subject: locking/static_keys: Add selftest
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=1987c947d905baa05bee430178e8eef882f36bd4;p=openwrt%2Fstaging%2Fblogic.git

locking/static_keys: Add selftest

Add a little selftest that validates all combinations.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/Kconfig b/arch/Kconfig
index 8a8ea7110de8..a71cdbe2a04d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -71,6 +71,12 @@ config JUMP_LABEL
 	 ( On 32-bit x86, the necessary options added to the compiler
 	   flags may increase the size of the kernel slightly. )
 
+config STATIC_KEYS_SELFTEST
+	bool "Static key selftest"
+	depends on JUMP_LABEL
+	help
+	  Boot time self-test of the branch patching code.
+
 config OPTPROBES
 	def_bool y
 	depends on KPROBES && HAVE_OPTPROBES
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 8fd00d892286..f7dd15d537f9 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -482,4 +482,41 @@ static void jump_label_update(struct static_key *key)
 		__jump_label_update(key, entry, stop);
 }
 
-#endif
+#ifdef CONFIG_STATIC_KEYS_SELFTEST
+static DEFINE_STATIC_KEY_TRUE(sk_true);
+static DEFINE_STATIC_KEY_FALSE(sk_false);
+
+static __init int jump_label_test(void)
+{
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		WARN_ON(static_key_enabled(&sk_true.key) != true);
+		WARN_ON(static_key_enabled(&sk_false.key) != false);
+
+		WARN_ON(!static_branch_likely(&sk_true));
+		WARN_ON(!static_branch_unlikely(&sk_true));
+		WARN_ON(static_branch_likely(&sk_false));
+		WARN_ON(static_branch_unlikely(&sk_false));
+
+		static_branch_disable(&sk_true);
+		static_branch_enable(&sk_false);
+
+		WARN_ON(static_key_enabled(&sk_true.key) == true);
+		WARN_ON(static_key_enabled(&sk_false.key) == false);
+
+		WARN_ON(static_branch_likely(&sk_true));
+		WARN_ON(static_branch_unlikely(&sk_true));
+		WARN_ON(!static_branch_likely(&sk_false));
+		WARN_ON(!static_branch_unlikely(&sk_false));
+
+		static_branch_enable(&sk_true);
+		static_branch_disable(&sk_false);
+	}
+
+	return 0;
+}
+late_initcall(jump_label_test);
+#endif /* STATIC_KEYS_SELFTEST */
+
+#endif /* HAVE_JUMP_LABEL */