livepatch: Selftests of the API for tracking system state changes

Four selftests for the new API.

Link: http://lkml.kernel.org/r/20191030154313.13263-6-pmladek@suse.com
To: Jiri Kosina <jikos@kernel.org>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: live-patching@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

4 files changed, 362 insertions, 1 deletions

diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
index 26900ddaef82..295b94bff370 100644
--- a/lib/livepatch/Makefile
+++ b/lib/livepatch/Makefile
@@ -8,7 +8,10 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
 				test_klp_callbacks_busy.o \
 				test_klp_callbacks_mod.o \
 				test_klp_livepatch.o \
-				test_klp_shadow_vars.o
+				test_klp_shadow_vars.o \
+				test_klp_state.o \
+				test_klp_state2.o \
+				test_klp_state3.o
 
 # Target modules to be livepatched require CC_FLAGS_FTRACE
 CFLAGS_test_klp_callbacks_busy.o	+= $(CC_FLAGS_FTRACE)
diff --git a/lib/livepatch/test_klp_state.c b/lib/livepatch/test_klp_state.c
new file mode 100644
index 000000000000..57a4253acb01
--- /dev/null
+++ b/lib/livepatch/test_klp_state.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 SUSE
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/livepatch.h>
+
+#define CONSOLE_LOGLEVEL_STATE 1
+/* Version 1 does not support migration. */
+#define CONSOLE_LOGLEVEL_STATE_VERSION 1
+
+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);
+}
+
+static struct klp_patch patch;
+
+static int allocate_loglevel_state(void)
+{
+	struct klp_state *loglevel_state;
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return -EINVAL;
+
+	loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
+	if (!loglevel_state->data)
+		return -ENOMEM;
+
+	pr_info("%s: allocating space to store console_loglevel\n",
+		__func__);
+	return 0;
+}
+
+static void fix_console_loglevel(void)
+{
+	struct klp_state *loglevel_state;
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	pr_info("%s: fixing console_loglevel\n", __func__);
+	*(int *)loglevel_state->data = console_loglevel;
+	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
+}
+
+static void restore_console_loglevel(void)
+{
+	struct klp_state *loglevel_state;
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	pr_info("%s: restoring console_loglevel\n", __func__);
+	console_loglevel = *(int *)loglevel_state->data;
+}
+
+static void free_loglevel_state(void)
+{
+	struct klp_state *loglevel_state;
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	pr_info("%s: freeing space for the stored console_loglevel\n",
+		__func__);
+	kfree(loglevel_state->data);
+}
+
+/* Executed on object patching (ie, patch enablement) */
+static int pre_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	return allocate_loglevel_state();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	fix_console_loglevel();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void pre_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	restore_console_loglevel();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	free_loglevel_state();
+}
+
+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_state states[] = {
+	{
+		.id = CONSOLE_LOGLEVEL_STATE,
+		.version = CONSOLE_LOGLEVEL_STATE_VERSION,
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+	.states = states,
+	.replace = true,
+};
+
+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("Petr Mladek <pmladek@suse.com>");
+MODULE_DESCRIPTION("Livepatch test: system state modification");
diff --git a/lib/livepatch/test_klp_state2.c b/lib/livepatch/test_klp_state2.c
new file mode 100644
index 000000000000..c978ea4d5e67
--- /dev/null
+++ b/lib/livepatch/test_klp_state2.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 SUSE
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/livepatch.h>
+
+#define CONSOLE_LOGLEVEL_STATE 1
+/* Version 2 supports migration. */
+#define CONSOLE_LOGLEVEL_STATE_VERSION 2
+
+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);
+}
+
+static struct klp_patch patch;
+
+static int allocate_loglevel_state(void)
+{
+	struct klp_state *loglevel_state, *prev_loglevel_state;
+
+	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
+	if (prev_loglevel_state) {
+		pr_info("%s: space to store console_loglevel already allocated\n",
+		__func__);
+		return 0;
+	}
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return -EINVAL;
+
+	loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
+	if (!loglevel_state->data)
+		return -ENOMEM;
+
+	pr_info("%s: allocating space to store console_loglevel\n",
+		__func__);
+	return 0;
+}
+
+static void fix_console_loglevel(void)
+{
+	struct klp_state *loglevel_state, *prev_loglevel_state;
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
+	if (prev_loglevel_state) {
+		pr_info("%s: taking over the console_loglevel change\n",
+		__func__);
+		loglevel_state->data = prev_loglevel_state->data;
+		return;
+	}
+
+	pr_info("%s: fixing console_loglevel\n", __func__);
+	*(int *)loglevel_state->data = console_loglevel;
+	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
+}
+
+static void restore_console_loglevel(void)
+{
+	struct klp_state *loglevel_state, *prev_loglevel_state;
+
+	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
+	if (prev_loglevel_state) {
+		pr_info("%s: passing the console_loglevel change back to the old livepatch\n",
+		__func__);
+		return;
+	}
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	pr_info("%s: restoring console_loglevel\n", __func__);
+	console_loglevel = *(int *)loglevel_state->data;
+}
+
+static void free_loglevel_state(void)
+{
+	struct klp_state *loglevel_state, *prev_loglevel_state;
+
+	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
+	if (prev_loglevel_state) {
+		pr_info("%s: keeping space to store console_loglevel\n",
+		__func__);
+		return;
+	}
+
+	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
+	if (!loglevel_state)
+		return;
+
+	pr_info("%s: freeing space for the stored console_loglevel\n",
+		__func__);
+	kfree(loglevel_state->data);
+}
+
+/* Executed on object patching (ie, patch enablement) */
+static int pre_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	return allocate_loglevel_state();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_patch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	fix_console_loglevel();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void pre_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	restore_console_loglevel();
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_unpatch_callback(struct klp_object *obj)
+{
+	callback_info(__func__, obj);
+	free_loglevel_state();
+}
+
+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_state states[] = {
+	{
+		.id = CONSOLE_LOGLEVEL_STATE,
+		.version = CONSOLE_LOGLEVEL_STATE_VERSION,
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+	.states = states,
+	.replace = true,
+};
+
+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("Petr Mladek <pmladek@suse.com>");
+MODULE_DESCRIPTION("Livepatch test: system state modification");
diff --git a/lib/livepatch/test_klp_state3.c b/lib/livepatch/test_klp_state3.c
new file mode 100644
index 000000000000..9226579d10c5
--- /dev/null
+++ b/lib/livepatch/test_klp_state3.c
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 SUSE
+
+/* The console loglevel fix is the same in the next cumulative patch. */
+#include "test_klp_state2.c"