jump_label: Provide a self-test

Signed-off-by: Jason Baron <jbaron@akamai.com>
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: benh@kernel.crashing.org
Cc: bp@alien8.de
Cc: davem@davemloft.net
Cc: ddaney@caviumnetworks.com
Cc: heiko.carstens@de.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: liuj97@gmail.com
Cc: luto@amacapital.net
Cc: michael@ellerman.id.au
Cc: rabin@rab.in
Cc: ralf@linux-mips.org
Cc: rostedt@goodmis.org
Cc: shuahkh@osg.samsung.com
Cc: vbabka@suse.cz
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/0c091ecebd78a879ed8a71835d205a691a75ab4e.1438227999.git.jbaron@akamai.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

lib/Kconfig.debug

@@ -1841,6 +1841,15 @@ config MEMTEST
 	        memtest=17, mean do 17 test patterns.
 	  If you are unsure how to answer this question, answer N.
 
+config TEST_JUMP_LABEL
+	tristate "Test jump label"
+	default n
+	depends on m
+	help
+	  Test jump labels.
+
+	  If unsure, say N.
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"

lib/Makefile

@@ -39,6 +39,8 @@ obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
 obj-$(CONFIG_TEST_LKM) += test_module.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
+obj-$(CONFIG_TEST_JUMP_LABEL) += test_jump_label.o
+obj-$(CONFIG_TEST_JUMP_LABEL) += test_jump_label_base.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG

lib/test_jump_label.c

@@ -0,0 +1,225 @@
+/*
+ * Kernel module for testing jump labels.
+ *
+ * Copyright 2015 Akamai Technologies Inc. All Rights Reserved
+ *
+ * Authors:
+ *      Jason Baron       <jbaron@akamai.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/jump_label.h>
+
+/* old keys */
+struct static_key old_true_key = STATIC_KEY_INIT_TRUE;
+struct static_key old_false_key = STATIC_KEY_INIT_FALSE;
+
+/* new api */
+DEFINE_STATIC_KEY_TRUE(true_key);
+DEFINE_STATIC_KEY_FALSE(false_key);
+
+/* external */
+extern struct static_key base_old_true_key;
+extern struct static_key base_inv_old_true_key;
+extern struct static_key base_old_false_key;
+extern struct static_key base_inv_old_false_key;
+
+/* new api */
+extern struct static_key_true base_true_key;
+extern struct static_key_true base_inv_true_key;
+extern struct static_key_false base_false_key;
+extern struct static_key_false base_inv_false_key;
+
+
+struct test_branch {
+	bool init_state;
+	struct static_key *key;
+	bool (*test_key)(void);
+};
+
+#define test_key_func(key, branch)	\
+({bool func(void) { return branch(key); } func;	})
+
+static void invert_key(struct static_key *key)
+{
+	if (static_key_enabled(key))
+		static_key_disable(key);
+	else
+		static_key_enable(key);
+}
+
+static void invert_keys(struct test_branch *branches, int size)
+{
+	struct static_key *previous = NULL;
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (previous != branches[i].key) {
+			invert_key(branches[i].key);
+			previous = branches[i].key;
+		}
+	}
+}
+
+int verify_branches(struct test_branch *branches, int size, bool invert)
+{
+	int i;
+	bool ret, init;
+
+	for (i = 0; i < size; i++) {
+		ret = static_key_enabled(branches[i].key);
+		init = branches[i].init_state;
+		if (ret != (invert ? !init : init))
+			return -EINVAL;
+		ret = branches[i].test_key();
+		if (static_key_enabled(branches[i].key)) {
+			if (!ret)
+				return -EINVAL;
+		} else {
+			if (ret)
+				return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static int __init test_jump_label_init(void)
+{
+	int ret;
+	int size;
+
+	struct test_branch jump_label_tests[] = {
+		/* internal keys - old keys */
+		{
+			.init_state = true,
+			.key = &old_true_key,
+			.test_key = test_key_func(&old_true_key, static_key_true),
+		},
+		{
+			.init_state = false,
+			.key = &old_false_key,
+			.test_key = test_key_func(&old_false_key, static_key_false),
+		},
+		/* internal keys - new keys */
+		{
+			.init_state = true,
+			.key = &true_key.key,
+			.test_key = test_key_func(&true_key, static_branch_likely),
+		},
+		{
+			.init_state = true,
+			.key = &true_key.key,
+			.test_key = test_key_func(&true_key, static_branch_unlikely),
+		},
+		{
+			.init_state = false,
+			.key = &false_key.key,
+			.test_key = test_key_func(&false_key, static_branch_likely),
+		},
+		{
+			.init_state = false,
+			.key = &false_key.key,
+			.test_key = test_key_func(&false_key, static_branch_unlikely),
+		},
+		/* external keys - old keys */
+		{
+			.init_state = true,
+			.key = &base_old_true_key,
+			.test_key = test_key_func(&base_old_true_key, static_key_true),
+		},
+		{
+			.init_state = false,
+			.key = &base_inv_old_true_key,
+			.test_key = test_key_func(&base_inv_old_true_key, static_key_true),
+		},
+		{
+			.init_state = false,
+			.key = &base_old_false_key,
+			.test_key = test_key_func(&base_old_false_key, static_key_false),
+		},
+		{
+			.init_state = true,
+			.key = &base_inv_old_false_key,
+			.test_key = test_key_func(&base_inv_old_false_key, static_key_false),
+		},
+		/* external keys - new keys */
+		{
+			.init_state = true,
+			.key = &base_true_key.key,
+			.test_key = test_key_func(&base_true_key, static_branch_likely),
+		},
+		{
+			.init_state = true,
+			.key = &base_true_key.key,
+			.test_key = test_key_func(&base_true_key, static_branch_unlikely),
+		},
+		{
+			.init_state = false,
+			.key = &base_inv_true_key.key,
+			.test_key = test_key_func(&base_inv_true_key, static_branch_likely),
+		},
+		{
+			.init_state = false,
+			.key = &base_inv_true_key.key,
+			.test_key = test_key_func(&base_inv_true_key, static_branch_unlikely),
+		},
+		{
+			.init_state = false,
+			.key = &base_false_key.key,
+			.test_key = test_key_func(&base_false_key, static_branch_likely),
+		},
+		{
+			.init_state = false,
+			.key = &base_false_key.key,
+			.test_key = test_key_func(&base_false_key, static_branch_unlikely),
+		},
+		{
+			.init_state = true,
+			.key = &base_inv_false_key.key,
+			.test_key = test_key_func(&base_inv_false_key, static_branch_likely),
+		},
+		{
+			.init_state = true,
+			.key = &base_inv_false_key.key,
+			.test_key = test_key_func(&base_inv_false_key, static_branch_unlikely),
+		},
+	};
+
+	size = ARRAY_SIZE(jump_label_tests);
+
+	ret = verify_branches(jump_label_tests, size, false);
+	if (ret)
+		goto out;
+
+	invert_keys(jump_label_tests, size);
+	ret = verify_branches(jump_label_tests, size, true);
+	if (ret)
+		goto out;
+
+	invert_keys(jump_label_tests, size);
+	ret = verify_branches(jump_label_tests, size, false);
+	if (ret)
+		goto out;
+	return 0;
+out:
+	return ret;
+}
+
+static void __exit test_jump_label_exit(void)
+{
+}
+
+module_init(test_jump_label_init);
+module_exit(test_jump_label_exit);
+
+MODULE_AUTHOR("Jason Baron <jbaron@akamai.com>");
+MODULE_LICENSE("GPL");

lib/test_jump_label_base.c

@@ -0,0 +1,68 @@
+/*
+ * Kernel module for testing jump labels.
+ *
+ * Copyright 2015 Akamai Technologies Inc. All Rights Reserved
+ *
+ * Authors:
+ *      Jason Baron       <jbaron@akamai.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/jump_label.h>
+
+/* old keys */
+struct static_key base_old_true_key = STATIC_KEY_INIT_TRUE;
+EXPORT_SYMBOL_GPL(base_old_true_key);
+struct static_key base_inv_old_true_key = STATIC_KEY_INIT_TRUE;
+EXPORT_SYMBOL_GPL(base_inv_old_true_key);
+struct static_key base_old_false_key = STATIC_KEY_INIT_FALSE;
+EXPORT_SYMBOL_GPL(base_old_false_key);
+struct static_key base_inv_old_false_key = STATIC_KEY_INIT_FALSE;
+EXPORT_SYMBOL_GPL(base_inv_old_false_key);
+
+/* new keys */
+DEFINE_STATIC_KEY_TRUE(base_true_key);
+EXPORT_SYMBOL_GPL(base_true_key);
+DEFINE_STATIC_KEY_TRUE(base_inv_true_key);
+EXPORT_SYMBOL_GPL(base_inv_true_key);
+DEFINE_STATIC_KEY_FALSE(base_false_key);
+EXPORT_SYMBOL_GPL(base_false_key);
+DEFINE_STATIC_KEY_FALSE(base_inv_false_key);
+EXPORT_SYMBOL_GPL(base_inv_false_key);
+
+static void invert_key(struct static_key *key)
+{
+	if (static_key_enabled(key))
+		static_key_disable(key);
+	else
+		static_key_enable(key);
+}
+
+static int __init test_jump_label_base_init(void)
+{
+	invert_key(&base_inv_old_true_key);
+	invert_key(&base_inv_old_false_key);
+	invert_key(&base_inv_true_key.key);
+	invert_key(&base_inv_false_key.key);
+
+	return 0;
+}
+
+static void __exit test_jump_label_base_exit(void)
+{
+}
+
+module_init(test_jump_label_base_init);
+module_exit(test_jump_label_base_exit);
+
+MODULE_AUTHOR("Jason Baron <jbaron@akamai.com>");
+MODULE_LICENSE("GPL");

tools/testing/selftests/Makefile

@@ -20,6 +20,7 @@ ifneq (1, $(quicktest))
 TARGETS += timers
 endif
 TARGETS += user
+TARGETS += jumplabel
 TARGETS += vm
 TARGETS += x86
 #Please keep the TARGETS list alphabetically sorted

tools/testing/selftests/jumplabel/Makefile

@@ -0,0 +1,8 @@
+# Makefile for jump label selftests
+
+# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
+all:
+
+TEST_PROGS := test_jump_label.sh
+
+include ../lib.mk

tools/testing/selftests/jumplabel/test_jump_label.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+# Runs jump label kernel module tests
+
+if /sbin/modprobe -q test_jump_label_base; then
+	if /sbin/modprobe -q test_jump_label; then
+		echo "jump_label: ok"
+		/sbin/modprobe -q -r test_jump_label
+		/sbin/modprobe -q -r test_jump_label_base
+	else
+		echo "jump_label: [FAIL]"
+		/sbin/modprobe -q -r test_jump_label_base
+	fi
+else
+	echo "jump_label: [FAIL]"
+	exit 1
+fi