selftests/livepatch: introduce tests

Add a few livepatch modules and simple target modules that the included
regression suite can run tests against:

  - basic livepatching (multiple patches, atomic replace)
  - pre/post (un)patch callbacks
  - shadow variable API

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Tested-by: Miroslav Benes <mbenes@suse.cz>
Tested-by: Alice Ferrazzi <alice.ferrazzi@gmail.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

10 files changed, 663 insertions, 1 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d4df5b24d75e..0298eb8eaa4e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1991,6 +1991,27 @@ config TEST_MEMCAT_P
 
 	  If unsure, say N.
 
+config TEST_LIVEPATCH
+	tristate "Test livepatching"
+	default n
+	depends on LIVEPATCH
+	depends on m
+	help
+	  Test kernel livepatching features for correctness.  The tests will
+	  load test modules that will be livepatched in various scenarios.
+
+	  To run all the livepatching tests:
+
+	  make -C tools/testing/selftests TARGETS=livepatch run_tests
+
+	  Alternatively, individual tests may be invoked:
+
+	  tools/testing/selftests/livepatch/test-callbacks.sh
+	  tools/testing/selftests/livepatch/test-livepatch.sh
+	  tools/testing/selftests/livepatch/test-shadow-vars.sh
+
+	  If unsure, say N.
+
 config TEST_OBJAGG
 	tristate "Perform selftest on object aggreration manager"
 	default n
@@ -1999,7 +2020,6 @@ config TEST_OBJAGG
 	  Enable this option to test object aggregation manager on boot
 	  (or module load).
 
-	  If unsure, say N.
 
 endif # RUNTIME_TESTING_MENU
 
diff --git a/lib/Makefile b/lib/Makefile
index e1b59da71418..a1cfa1975ca3 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -77,6 +77,8 @@ obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
 obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
 obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
 
+obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/
+
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG
 CFLAGS_kobject_uevent.o += -DDEBUG
diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
new file mode 100644
index 000000000000..26900ddaef82
--- /dev/null
+++ b/lib/livepatch/Makefile
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for livepatch test code.
+
+obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
+				test_klp_callbacks_demo.o \
+				test_klp_callbacks_demo2.o \
+				test_klp_callbacks_busy.o \
+				test_klp_callbacks_mod.o \
+				test_klp_livepatch.o \
+				test_klp_shadow_vars.o
+
+# Target modules to be livepatched require CC_FLAGS_FTRACE
+CFLAGS_test_klp_callbacks_busy.o	+= $(CC_FLAGS_FTRACE)
+CFLAGS_test_klp_callbacks_mod.o		+= $(CC_FLAGS_FTRACE)
diff --git a/lib/livepatch/test_klp_atomic_replace.c b/lib/livepatch/test_klp_atomic_replace.c
new file mode 100644
index 000000000000..5af7093ca00c
--- /dev/null
+++ b/lib/livepatch/test_klp_atomic_replace.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+static int replace;
+module_param(replace, int, 0644);
+MODULE_PARM_DESC(replace, "replace (default=0)");
+
+#include <linux/seq_file.h>
+static int livepatch_meminfo_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s: %s\n", THIS_MODULE->name,
+		   "this has been live patched");
+	return 0;
+}
+
+static struct klp_func funcs[] = {
+	{
+		.old_name = "meminfo_proc_show",
+		.new_func = livepatch_meminfo_proc_show,
+	}, {}
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	}, {}
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+	/* set .replace in the init function below for demo purposes */
+};
+
+static int test_klp_atomic_replace_init(void)
+{
+	patch.replace = replace;
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_atomic_replace_exit(void)
+{
+}
+
+module_init(test_klp_atomic_replace_init);
+module_exit(test_klp_atomic_replace_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: atomic replace");
diff --git a/lib/livepatch/test_klp_callbacks_busy.c b/lib/livepatch/test_klp_callbacks_busy.c
new file mode 100644
index 000000000000..40beddf8a0e2
--- /dev/null
+++ b/lib/livepatch/test_klp_callbacks_busy.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/workqueue.h>
+#include <linux/delay.h>
+
+static int sleep_secs;
+module_param(sleep_secs, int, 0644);
+MODULE_PARM_DESC(sleep_secs, "sleep_secs (default=0)");
+
+static void busymod_work_func(struct work_struct *work);
+static DECLARE_DELAYED_WORK(work, busymod_work_func);
+
+static void busymod_work_func(struct work_struct *work)
+{
+	pr_info("%s, sleeping %d seconds ...\n", __func__, sleep_secs);
+	msleep(sleep_secs * 1000);
+	pr_info("%s exit\n", __func__);
+}
+
+static int test_klp_callbacks_busy_init(void)
+{
+	pr_info("%s\n", __func__);
+	schedule_delayed_work(&work,
+		msecs_to_jiffies(1000 * 0));
+	return 0;
+}
+
+static void test_klp_callbacks_busy_exit(void)
+{
+	cancel_delayed_work_sync(&work);
+	pr_info("%s\n", __func__);
+}
+
+module_init(test_klp_callbacks_busy_init);
+module_exit(test_klp_callbacks_busy_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: busy target module");
diff --git a/lib/livepatch/test_klp_callbacks_demo.c b/lib/livepatch/test_klp_callbacks_demo.c
new file mode 100644
index 000000000000..3fd8fe1cd1cc
--- /dev/null
+++ b/lib/livepatch/test_klp_callbacks_demo.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+static int pre_patch_ret;
+module_param(pre_patch_ret, int, 0644);
+MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret (default=0)");
+
+static const char *const module_state[] = {
+	[MODULE_STATE_LIVE]	= "[MODULE_STATE_LIVE] Normal state",
+	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
+	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
+	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+};
+
+static void callback_info(const char *callback, struct klp_object *obj)
+{
+	if (obj->mod)
+		pr_info("%s: %s -> %s\n", callback, obj->mod->name,
+			module_state[obj->mod->state]);
+	else
+		pr_info("%s: vmlinux\n", callback);
+}
+
+/* Executed on object patching (ie, patch enablement) */
+static int pre_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	return pre_patch_ret;
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void pre_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+static void patched_work_func(struct work_struct *work)
+{
+	pr_info("%s\n", __func__);
+}
+
+static struct klp_func no_funcs[] = {
+	{}
+};
+
+static struct klp_func busymod_funcs[] = {
+	{
+		.old_name = "busymod_work_func",
+		.new_func = patched_work_func,
+	}, {}
+};
+
+static struct klp_object objs[] = {
+	{
+		.name = NULL,	/* vmlinux */
+		.funcs = no_funcs,
+		.callbacks = {
+			.pre_patch = pre_patch_callback,
+			.post_patch = post_patch_callback,
+			.pre_unpatch = pre_unpatch_callback,
+			.post_unpatch = post_unpatch_callback,
+		},
+	},	{
+		.name = "test_klp_callbacks_mod",
+		.funcs = no_funcs,
+		.callbacks = {
+			.pre_patch = pre_patch_callback,
+			.post_patch = post_patch_callback,
+			.pre_unpatch = pre_unpatch_callback,
+			.post_unpatch = post_unpatch_callback,
+		},
+	},	{
+		.name = "test_klp_callbacks_busy",
+		.funcs = busymod_funcs,
+		.callbacks = {
+			.pre_patch = pre_patch_callback,
+			.post_patch = post_patch_callback,
+			.pre_unpatch = pre_unpatch_callback,
+			.post_unpatch = post_unpatch_callback,
+		},
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int test_klp_callbacks_demo_init(void)
+{
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_callbacks_demo_exit(void)
+{
+}
+
+module_init(test_klp_callbacks_demo_init);
+module_exit(test_klp_callbacks_demo_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: livepatch demo");
diff --git a/lib/livepatch/test_klp_callbacks_demo2.c b/lib/livepatch/test_klp_callbacks_demo2.c
new file mode 100644
index 000000000000..5417573e80af
--- /dev/null
+++ b/lib/livepatch/test_klp_callbacks_demo2.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+static int replace;
+module_param(replace, int, 0644);
+MODULE_PARM_DESC(replace, "replace (default=0)");
+
+static const char *const module_state[] = {
+	[MODULE_STATE_LIVE]	= "[MODULE_STATE_LIVE] Normal state",
+	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
+	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
+	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+};
+
+static void callback_info(const char *callback, struct klp_object *obj)
+{
+	if (obj->mod)
+		pr_info("%s: %s -> %s\n", callback, obj->mod->name,
+			module_state[obj->mod->state]);
+	else
+		pr_info("%s: vmlinux\n", callback);
+}
+
+/* Executed on object patching (ie, patch enablement) */
+static int pre_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	return 0;
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void pre_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+}
+
+static struct klp_func no_funcs[] = {
+	{ }
+};
+
+static struct klp_object objs[] = {
+	{
+		.name = NULL,	/* vmlinux */
+		.funcs = no_funcs,
+		.callbacks = {
+			.pre_patch = pre_patch_callback,
+			.post_patch = post_patch_callback,
+			.pre_unpatch = pre_unpatch_callback,
+			.post_unpatch = post_unpatch_callback,
+		},
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+	/* set .replace in the init function below for demo purposes */
+};
+
+static int test_klp_callbacks_demo2_init(void)
+{
+	patch.replace = replace;
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_callbacks_demo2_exit(void)
+{
+}
+
+module_init(test_klp_callbacks_demo2_init);
+module_exit(test_klp_callbacks_demo2_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: livepatch demo2");
diff --git a/lib/livepatch/test_klp_callbacks_mod.c b/lib/livepatch/test_klp_callbacks_mod.c
new file mode 100644
index 000000000000..8fbe645b1c2c
--- /dev/null
+++ b/lib/livepatch/test_klp_callbacks_mod.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+static int test_klp_callbacks_mod_init(void)
+{
+	pr_info("%s\n", __func__);
+	return 0;
+}
+
+static void test_klp_callbacks_mod_exit(void)
+{
+	pr_info("%s\n", __func__);
+}
+
+module_init(test_klp_callbacks_mod_init);
+module_exit(test_klp_callbacks_mod_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: target module");
diff --git a/lib/livepatch/test_klp_livepatch.c b/lib/livepatch/test_klp_livepatch.c
new file mode 100644
index 000000000000..aff08199de71
--- /dev/null
+++ b/lib/livepatch/test_klp_livepatch.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+#include <linux/seq_file.h>
+static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s: %s\n", THIS_MODULE->name,
+		   "this has been live patched");
+	return 0;
+}
+
+static struct klp_func funcs[] = {
+	{
+		.old_name = "cmdline_proc_show",
+		.new_func = livepatch_cmdline_proc_show,
+	}, { }
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int test_klp_livepatch_init(void)
+{
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_livepatch_exit(void)
+{
+}
+
+module_init(test_klp_livepatch_init);
+module_exit(test_klp_livepatch_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_AUTHOR("Seth Jennings <sjenning@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: livepatch module");
diff --git a/lib/livepatch/test_klp_shadow_vars.c b/lib/livepatch/test_klp_shadow_vars.c
new file mode 100644
index 000000000000..02f892f941dc
--- /dev/null
+++ b/lib/livepatch/test_klp_shadow_vars.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/livepatch.h>
+#include <linux/slab.h>
+
+/*
+ * Keep a small list of pointers so that we can print address-agnostic
+ * pointer values.  Use a rolling integer count to differentiate the values.
+ * Ironically we could have used the shadow variable API to do this, but
+ * let's not lean too heavily on the very code we're testing.
+ */
+static LIST_HEAD(ptr_list);
+struct shadow_ptr {
+	void *ptr;
+	int id;
+	struct list_head list;
+};
+
+static void free_ptr_list(void)
+{
+	struct shadow_ptr *sp, *tmp_sp;
+
+	list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
+		list_del(&sp->list);
+		kfree(sp);
+	}
+}
+
+static int ptr_id(void *ptr)
+{
+	struct shadow_ptr *sp;
+	static int count;
+
+	list_for_each_entry(sp, &ptr_list, list) {
+		if (sp->ptr == ptr)
+			return sp->id;
+	}
+
+	sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
+	if (!sp)
+		return -1;
+	sp->ptr = ptr;
+	sp->id = count++;
+
+	list_add(&sp->list, &ptr_list);
+
+	return sp->id;
+}
+
+/*
+ * Shadow variable wrapper functions that echo the function and arguments
+ * to the kernel log for testing verification.  Don't display raw pointers,
+ * but use the ptr_id() value instead.
+ */
+static void *shadow_get(void *obj, unsigned long id)
+{
+	void *ret = klp_shadow_get(obj, id);
+
+	pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
+		__func__, ptr_id(obj), id, ptr_id(ret));
+
+	return ret;
+}
+
+static void *shadow_alloc(void *obj, unsigned long id, size_t size,
+			  gfp_t gfp_flags, klp_shadow_ctor_t ctor,
+			  void *ctor_data)
+{
+	void *ret = klp_shadow_alloc(obj, id, size, gfp_flags, ctor,
+				     ctor_data);
+	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
+		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
+		ptr_id(ctor_data), ptr_id(ret));
+	return ret;
+}
+
+static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
+				 gfp_t gfp_flags, klp_shadow_ctor_t ctor,
+				 void *ctor_data)
+{
+	void *ret = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor,
+					    ctor_data);
+	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
+		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
+		ptr_id(ctor_data), ptr_id(ret));
+	return ret;
+}
+
+static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
+{
+	klp_shadow_free(obj, id, dtor);
+	pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
+		__func__, ptr_id(obj), id, ptr_id(dtor));
+}
+
+static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
+{
+	klp_shadow_free_all(id, dtor);
+	pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n",
+		__func__, id, ptr_id(dtor));
+}
+
+
+/* Shadow variable constructor - remember simple pointer data */
+static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
+{
+	int **shadow_int = shadow_data;
+	*shadow_int = ctor_data;
+	pr_info("%s: PTR%d -> PTR%d\n",
+		__func__, ptr_id(shadow_int), ptr_id(ctor_data));
+
+	return 0;
+}
+
+static void shadow_dtor(void *obj, void *shadow_data)
+{
+	pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
+		__func__, ptr_id(obj), ptr_id(shadow_data));
+}
+
+static int test_klp_shadow_vars_init(void)
+{
+	void *obj			= THIS_MODULE;
+	int id			= 0x1234;
+	size_t size		= sizeof(int *);
+	gfp_t gfp_flags		= GFP_KERNEL;
+
+	int var1, var2, var3, var4;
+	int **sv1, **sv2, **sv3, **sv4;
+
+	void *ret;
+
+	ptr_id(NULL);
+	ptr_id(&var1);
+	ptr_id(&var2);
+	ptr_id(&var3);
+	ptr_id(&var4);
+
+	/*
+	 * With an empty shadow variable hash table, expect not to find
+	 * any matches.
+	 */
+	ret = shadow_get(obj, id);
+	if (!ret)
+		pr_info("  got expected NULL result\n");
+
+	/*
+	 * Allocate a few shadow variables with different <obj> and <id>.
+	 */
+	sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);
+	sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);
+	sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);
+
+	/*
+	 * Verify we can find our new shadow variables and that they point
+	 * to expected data.
+	 */
+	ret = shadow_get(obj, id);
+	if (ret == sv1 && *sv1 == &var1)
+		pr_info("  got expected PTR%d -> PTR%d result\n",
+			ptr_id(sv1), ptr_id(*sv1));
+	ret = shadow_get(obj + 1, id);
+	if (ret == sv2 && *sv2 == &var2)
+		pr_info("  got expected PTR%d -> PTR%d result\n",
+			ptr_id(sv2), ptr_id(*sv2));
+	ret = shadow_get(obj, id + 1);
+	if (ret == sv3 && *sv3 == &var3)
+		pr_info("  got expected PTR%d -> PTR%d result\n",
+			ptr_id(sv3), ptr_id(*sv3));
+
+	/*
+	 * Allocate or get a few more, this time with the same <obj>, <id>.
+	 * The second invocation should return the same shadow var.
+	 */
+	sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
+	ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
+	if (ret == sv4 && *sv4 == &var4)
+		pr_info("  got expected PTR%d -> PTR%d result\n",
+			ptr_id(sv4), ptr_id(*sv4));
+
+	/*
+	 * Free the <obj=*, id> shadow variables and check that we can no
+	 * longer find them.
+	 */
+	shadow_free(obj, id, shadow_dtor);			/* sv1 */
+	ret = shadow_get(obj, id);
+	if (!ret)
+		pr_info("  got expected NULL result\n");
+
+	shadow_free(obj + 1, id, shadow_dtor);			/* sv2 */
+	ret = shadow_get(obj + 1, id);
+	if (!ret)
+		pr_info("  got expected NULL result\n");
+
+	shadow_free(obj + 2, id, shadow_dtor);			/* sv4 */
+	ret = shadow_get(obj + 2, id);
+	if (!ret)
+		pr_info("  got expected NULL result\n");
+
+	/*
+	 * We should still find an <id+1> variable.
+	 */
+	ret = shadow_get(obj, id + 1);
+	if (ret == sv3 && *sv3 == &var3)
+		pr_info("  got expected PTR%d -> PTR%d result\n",
+			ptr_id(sv3), ptr_id(*sv3));
+
+	/*
+	 * Free all the <id+1> variables, too.
+	 */
+	shadow_free_all(id + 1, shadow_dtor);			/* sv3 */
+	ret = shadow_get(obj, id);
+	if (!ret)
+		pr_info("  shadow_get() got expected NULL result\n");
+
+
+	free_ptr_list();
+
+	return 0;
+}
+
+static void test_klp_shadow_vars_exit(void)
+{
+}
+
+module_init(test_klp_shadow_vars_init);
+module_exit(test_klp_shadow_vars_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: shadow variables");