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authorLinus Torvalds <torvalds@linux-foundation.org>2019-11-25 19:43:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-11-25 19:43:48 -0800
commitf838767555d40f29bc4771c5c8cc63193094b7cc (patch)
tree50d126b8fd20a8f50e13263529805e8eaea73db3
parent436b2a8039ac00f8dc6ae8f3bd2be83748f72312 (diff)
parent0e672adc87e5ae1758b6e0571b42d743a8324327 (diff)
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Merge tag 'livepatching-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching updates from Petr Mladek: - New API to track system state changes done be livepatch callbacks. It helps to maintain compatibility between livepatches. - Update Kconfig help text. ORC is another reliable unwinder. - Disable generic selftest timeout. Livepatch selftests have their own per-operation fine-grained timeouts. * tag 'livepatching-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: x86/stacktrace: update kconfig help text for reliable unwinders livepatch: Selftests of the API for tracking system state changes livepatch: Documentation of the new API for tracking system state changes livepatch: Allow to distinguish different version of system state changes livepatch: Basic API to track system state changes livepatch: Keep replaced patches until post_patch callback is called selftests/livepatch: Disable the timeout
-rw-r--r--Documentation/livepatch/index.rst1
-rw-r--r--Documentation/livepatch/system-state.rst167
-rw-r--r--arch/x86/Kconfig.debug4
-rw-r--r--include/linux/livepatch.h17
-rw-r--r--kernel/livepatch/Makefile2
-rw-r--r--kernel/livepatch/core.c44
-rw-r--r--kernel/livepatch/core.h5
-rw-r--r--kernel/livepatch/state.c119
-rw-r--r--kernel/livepatch/state.h9
-rw-r--r--kernel/livepatch/transition.c12
-rw-r--r--lib/livepatch/Makefile5
-rw-r--r--lib/livepatch/test_klp_state.c162
-rw-r--r--lib/livepatch/test_klp_state2.c191
-rw-r--r--lib/livepatch/test_klp_state3.c5
-rw-r--r--tools/testing/selftests/livepatch/Makefile3
-rw-r--r--tools/testing/selftests/livepatch/settings1
-rwxr-xr-xtools/testing/selftests/livepatch/test-state.sh180
17 files changed, 902 insertions, 25 deletions
diff --git a/Documentation/livepatch/index.rst b/Documentation/livepatch/index.rst
index 17674a9e21b2..525944063be7 100644
--- a/Documentation/livepatch/index.rst
+++ b/Documentation/livepatch/index.rst
@@ -12,6 +12,7 @@ Kernel Livepatching
cumulative-patches
module-elf-format
shadow-vars
+ system-state
.. only:: subproject and html
diff --git a/Documentation/livepatch/system-state.rst b/Documentation/livepatch/system-state.rst
new file mode 100644
index 000000000000..c6d127c2d9aa
--- /dev/null
+++ b/Documentation/livepatch/system-state.rst
@@ -0,0 +1,167 @@
+====================
+System State Changes
+====================
+
+Some users are really reluctant to reboot a system. This brings the need
+to provide more livepatches and maintain some compatibility between them.
+
+Maintaining more livepatches is much easier with cumulative livepatches.
+Each new livepatch completely replaces any older one. It can keep,
+add, and even remove fixes. And it is typically safe to replace any version
+of the livepatch with any other one thanks to the atomic replace feature.
+
+The problems might come with shadow variables and callbacks. They might
+change the system behavior or state so that it is no longer safe to
+go back and use an older livepatch or the original kernel code. Also
+any new livepatch must be able to detect what changes have already been
+done by the already installed livepatches.
+
+This is where the livepatch system state tracking gets useful. It
+allows to:
+
+ - store data needed to manipulate and restore the system state
+
+ - define compatibility between livepatches using a change id
+ and version
+
+
+1. Livepatch system state API
+=============================
+
+The state of the system might get modified either by several livepatch callbacks
+or by the newly used code. Also it must be possible to find changes done by
+already installed livepatches.
+
+Each modified state is described by struct klp_state, see
+include/linux/livepatch.h.
+
+Each livepatch defines an array of struct klp_states. They mention
+all states that the livepatch modifies.
+
+The livepatch author must define the following two fields for each
+struct klp_state:
+
+ - *id*
+
+ - Non-zero number used to identify the affected system state.
+
+ - *version*
+
+ - Number describing the variant of the system state change that
+ is supported by the given livepatch.
+
+The state can be manipulated using two functions:
+
+ - *klp_get_state(patch, id)*
+
+ - Get struct klp_state associated with the given livepatch
+ and state id.
+
+ - *klp_get_prev_state(id)*
+
+ - Get struct klp_state associated with the given feature id and
+ already installed livepatches.
+
+2. Livepatch compatibility
+==========================
+
+The system state version is used to prevent loading incompatible livepatches.
+The check is done when the livepatch is enabled. The rules are:
+
+ - Any completely new system state modification is allowed.
+
+ - System state modifications with the same or higher version are allowed
+ for already modified system states.
+
+ - Cumulative livepatches must handle all system state modifications from
+ already installed livepatches.
+
+ - Non-cumulative livepatches are allowed to touch already modified
+ system states.
+
+3. Supported scenarios
+======================
+
+Livepatches have their life-cycle and the same is true for the system
+state changes. Every compatible livepatch has to support the following
+scenarios:
+
+ - Modify the system state when the livepatch gets enabled and the state
+ has not been already modified by a livepatches that are being
+ replaced.
+
+ - Take over or update the system state modification when is has already
+ been done by a livepatch that is being replaced.
+
+ - Restore the original state when the livepatch is disabled.
+
+ - Restore the previous state when the transition is reverted.
+ It might be the original system state or the state modification
+ done by livepatches that were being replaced.
+
+ - Remove any already made changes when error occurs and the livepatch
+ cannot get enabled.
+
+4. Expected usage
+=================
+
+System states are usually modified by livepatch callbacks. The expected
+role of each callback is as follows:
+
+*pre_patch()*
+
+ - Allocate *state->data* when necessary. The allocation might fail
+ and *pre_patch()* is the only callback that could stop loading
+ of the livepatch. The allocation is not needed when the data
+ are already provided by previously installed livepatches.
+
+ - Do any other preparatory action that is needed by
+ the new code even before the transition gets finished.
+ For example, initialize *state->data*.
+
+ The system state itself is typically modified in *post_patch()*
+ when the entire system is able to handle it.
+
+ - Clean up its own mess in case of error. It might be done by a custom
+ code or by calling *post_unpatch()* explicitly.
+
+*post_patch()*
+
+ - Copy *state->data* from the previous livepatch when they are
+ compatible.
+
+ - Do the actual system state modification. Eventually allow
+ the new code to use it.
+
+ - Make sure that *state->data* has all necessary information.
+
+ - Free *state->data* from replaces livepatches when they are
+ not longer needed.
+
+*pre_unpatch()*
+
+ - Prevent the code, added by the livepatch, relying on the system
+ state change.
+
+ - Revert the system state modification..
+
+*post_unpatch()*
+
+ - Distinguish transition reverse and livepatch disabling by
+ checking *klp_get_prev_state()*.
+
+ - In case of transition reverse, restore the previous system
+ state. It might mean doing nothing.
+
+ - Remove any not longer needed setting or data.
+
+.. note::
+
+ *pre_unpatch()* typically does symmetric operations to *post_patch()*.
+ Except that it is called only when the livepatch is being disabled.
+ Therefore it does not need to care about any previously installed
+ livepatch.
+
+ *post_unpatch()* typically does symmetric operations to *pre_patch()*.
+ It might be called also during the transition reverse. Therefore it
+ has to handle the state of the previously installed livepatches.
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index bf9cd83de777..409c00f74e60 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -316,10 +316,6 @@ config UNWINDER_FRAME_POINTER
unwinder, but the kernel text size will grow by ~3% and the kernel's
overall performance will degrade by roughly 5-10%.
- This option is recommended if you want to use the livepatch
- consistency model, as this is currently the only way to get a
- reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).
-
config UNWINDER_GUESS
bool "Guess unwinder"
depends on EXPERT
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 273400814020..e894e74905f3 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -131,9 +131,22 @@ struct klp_object {
};
/**
+ * struct klp_state - state of the system modified by the livepatch
+ * @id: system state identifier (non-zero)
+ * @version: version of the change
+ * @data: custom data
+ */
+struct klp_state {
+ unsigned long id;
+ unsigned int version;
+ void *data;
+};
+
+/**
* struct klp_patch - patch structure for live patching
* @mod: reference to the live patch module
* @objs: object entries for kernel objects to be patched
+ * @states: system states that can get modified
* @replace: replace all actively used patches
* @list: list node for global list of actively used patches
* @kobj: kobject for sysfs resources
@@ -147,6 +160,7 @@ struct klp_patch {
/* external */
struct module *mod;
struct klp_object *objs;
+ struct klp_state *states;
bool replace;
/* internal */
@@ -217,6 +231,9 @@ void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
+struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id);
+struct klp_state *klp_get_prev_state(unsigned long id);
+
#else /* !CONFIG_LIVEPATCH */
static inline int klp_module_coming(struct module *mod) { return 0; }
diff --git a/kernel/livepatch/Makefile b/kernel/livepatch/Makefile
index cf9b5bcdb952..cf03d4bdfc66 100644
--- a/kernel/livepatch/Makefile
+++ b/kernel/livepatch/Makefile
@@ -1,4 +1,4 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_LIVEPATCH) += livepatch.o
-livepatch-objs := core.o patch.o shadow.o transition.o
+livepatch-objs := core.o patch.o shadow.o state.o transition.o
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index ab4a4606d19b..c3512e7e0801 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -22,6 +22,7 @@
#include <asm/cacheflush.h>
#include "core.h"
#include "patch.h"
+#include "state.h"
#include "transition.h"
/*
@@ -632,7 +633,7 @@ static void klp_free_objects_dynamic(struct klp_patch *patch)
* The operation must be completed by calling klp_free_patch_finish()
* outside klp_mutex.
*/
-void klp_free_patch_start(struct klp_patch *patch)
+static void klp_free_patch_start(struct klp_patch *patch)
{
if (!list_empty(&patch->list))
list_del(&patch->list);
@@ -677,6 +678,23 @@ static void klp_free_patch_work_fn(struct work_struct *work)
klp_free_patch_finish(patch);
}
+void klp_free_patch_async(struct klp_patch *patch)
+{
+ klp_free_patch_start(patch);
+ schedule_work(&patch->free_work);
+}
+
+void klp_free_replaced_patches_async(struct klp_patch *new_patch)
+{
+ struct klp_patch *old_patch, *tmp_patch;
+
+ klp_for_each_patch_safe(old_patch, tmp_patch) {
+ if (old_patch == new_patch)
+ return;
+ klp_free_patch_async(old_patch);
+ }
+}
+
static int klp_init_func(struct klp_object *obj, struct klp_func *func)
{
if (!func->old_name)
@@ -992,6 +1010,13 @@ int klp_enable_patch(struct klp_patch *patch)
mutex_lock(&klp_mutex);
+ if (!klp_is_patch_compatible(patch)) {
+ pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
+ patch->mod->name);
+ mutex_unlock(&klp_mutex);
+ return -EINVAL;
+ }
+
ret = klp_init_patch_early(patch);
if (ret) {
mutex_unlock(&klp_mutex);
@@ -1022,12 +1047,13 @@ err:
EXPORT_SYMBOL_GPL(klp_enable_patch);
/*
- * This function removes replaced patches.
+ * This function unpatches objects from the replaced livepatches.
*
* We could be pretty aggressive here. It is called in the situation where
- * these structures are no longer accessible. All functions are redirected
- * by the klp_transition_patch. They use either a new code or they are in
- * the original code because of the special nop function patches.
+ * these structures are no longer accessed from the ftrace handler.
+ * All functions are redirected by the klp_transition_patch. They
+ * use either a new code or they are in the original code because
+ * of the special nop function patches.
*
* The only exception is when the transition was forced. In this case,
* klp_ftrace_handler() might still see the replaced patch on the stack.
@@ -1035,18 +1061,16 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
* thanks to RCU. We only have to keep the patches on the system. Also
* this is handled transparently by patch->module_put.
*/
-void klp_discard_replaced_patches(struct klp_patch *new_patch)
+void klp_unpatch_replaced_patches(struct klp_patch *new_patch)
{
- struct klp_patch *old_patch, *tmp_patch;
+ struct klp_patch *old_patch;
- klp_for_each_patch_safe(old_patch, tmp_patch) {
+ klp_for_each_patch(old_patch) {
if (old_patch == new_patch)
return;
old_patch->enabled = false;
klp_unpatch_objects(old_patch);
- klp_free_patch_start(old_patch);
- schedule_work(&old_patch->free_work);
}
}
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index ec43a40b853f..38209c7361b6 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -13,8 +13,9 @@ extern struct list_head klp_patches;
#define klp_for_each_patch(patch) \
list_for_each_entry(patch, &klp_patches, list)
-void klp_free_patch_start(struct klp_patch *patch);
-void klp_discard_replaced_patches(struct klp_patch *new_patch);
+void klp_free_patch_async(struct klp_patch *patch);
+void klp_free_replaced_patches_async(struct klp_patch *new_patch);
+void klp_unpatch_replaced_patches(struct klp_patch *new_patch);
void klp_discard_nops(struct klp_patch *new_patch);
static inline bool klp_is_object_loaded(struct klp_object *obj)
diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c
new file mode 100644
index 000000000000..7ee19476de9d
--- /dev/null
+++ b/kernel/livepatch/state.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * system_state.c - State of the system modified by livepatches
+ *
+ * Copyright (C) 2019 SUSE
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/livepatch.h>
+#include "core.h"
+#include "state.h"
+#include "transition.h"
+
+#define klp_for_each_state(patch, state) \
+ for (state = patch->states; state && state->id; state++)
+
+/**
+ * klp_get_state() - get information about system state modified by
+ * the given patch
+ * @patch: livepatch that modifies the given system state
+ * @id: custom identifier of the modified system state
+ *
+ * Checks whether the given patch modifies the given system state.
+ *
+ * The function can be called either from pre/post (un)patch
+ * callbacks or from the kernel code added by the livepatch.
+ *
+ * Return: pointer to struct klp_state when found, otherwise NULL.
+ */
+struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id)
+{
+ struct klp_state *state;
+
+ klp_for_each_state(patch, state) {
+ if (state->id == id)
+ return state;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(klp_get_state);
+
+/**
+ * klp_get_prev_state() - get information about system state modified by
+ * the already installed livepatches
+ * @id: custom identifier of the modified system state
+ *
+ * Checks whether already installed livepatches modify the given
+ * system state.
+ *
+ * The same system state can be modified by more non-cumulative
+ * livepatches. It is expected that the latest livepatch has
+ * the most up-to-date information.
+ *
+ * The function can be called only during transition when a new
+ * livepatch is being enabled or when such a transition is reverted.
+ * It is typically called only from from pre/post (un)patch
+ * callbacks.
+ *
+ * Return: pointer to the latest struct klp_state from already
+ * installed livepatches, NULL when not found.
+ */
+struct klp_state *klp_get_prev_state(unsigned long id)
+{
+ struct klp_patch *patch;
+ struct klp_state *state, *last_state = NULL;
+
+ if (WARN_ON_ONCE(!klp_transition_patch))
+ return NULL;
+
+ klp_for_each_patch(patch) {
+ if (patch == klp_transition_patch)
+ goto out;
+
+ state = klp_get_state(patch, id);
+ if (state)
+ last_state = state;
+ }
+
+out:
+ return last_state;
+}
+EXPORT_SYMBOL_GPL(klp_get_prev_state);
+
+/* Check if the patch is able to deal with the existing system state. */
+static bool klp_is_state_compatible(struct klp_patch *patch,
+ struct klp_state *old_state)
+{
+ struct klp_state *state;
+
+ state = klp_get_state(patch, old_state->id);
+
+ /* A cumulative livepatch must handle all already modified states. */
+ if (!state)
+ return !patch->replace;
+
+ return state->version >= old_state->version;
+}
+
+/*
+ * Check that the new livepatch will not break the existing system states.
+ * Cumulative patches must handle all already modified states.
+ * Non-cumulative patches can touch already modified states.
+ */
+bool klp_is_patch_compatible(struct klp_patch *patch)
+{
+ struct klp_patch *old_patch;
+ struct klp_state *old_state;
+
+ klp_for_each_patch(old_patch) {
+ klp_for_each_state(old_patch, old_state) {
+ if (!klp_is_state_compatible(patch, old_state))
+ return false;
+ }
+ }
+
+ return true;
+}
diff --git a/kernel/livepatch/state.h b/kernel/livepatch/state.h
new file mode 100644
index 000000000000..49d9c16e8762
--- /dev/null
+++ b/kernel/livepatch/state.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LIVEPATCH_STATE_H
+#define _LIVEPATCH_STATE_H
+
+#include <linux/livepatch.h>
+
+bool klp_is_patch_compatible(struct klp_patch *patch);
+
+#endif /* _LIVEPATCH_STATE_H */
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index cdf318d86dd6..f6310f848f34 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -78,7 +78,7 @@ static void klp_complete_transition(void)
klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
if (klp_transition_patch->replace && klp_target_state == KLP_PATCHED) {
- klp_discard_replaced_patches(klp_transition_patch);
+ klp_unpatch_replaced_patches(klp_transition_patch);
klp_discard_nops(klp_transition_patch);
}
@@ -446,14 +446,14 @@ void klp_try_complete_transition(void)
klp_complete_transition();
/*
- * It would make more sense to free the patch in
+ * It would make more sense to free the unused patches in
* klp_complete_transition() but it is called also
* from klp_cancel_transition().
*/
- if (!patch->enabled) {
- klp_free_patch_start(patch);
- schedule_work(&patch->free_work);
- }
+ if (!patch->enabled)
+ klp_free_patch_async(patch);
+ else if (patch->replace)
+ klp_free_replaced_patches_async(patch);
}
/*
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"
diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
index fd405402c3ff..1cf40a9e7185 100644
--- a/tools/testing/selftests/livepatch/Makefile
+++ b/tools/testing/selftests/livepatch/Makefile
@@ -4,6 +4,7 @@ TEST_PROGS_EXTENDED := functions.sh
TEST_PROGS := \
test-livepatch.sh \
test-callbacks.sh \
- test-shadow-vars.sh
+ test-shadow-vars.sh \
+ test-state.sh
include ../lib.mk
diff --git a/tools/testing/selftests/livepatch/settings b/tools/testing/selftests/livepatch/settings
new file mode 100644
index 000000000000..e7b9417537fb
--- /dev/null
+++ b/tools/testing/selftests/livepatch/settings
@@ -0,0 +1 @@
+timeout=0
diff --git a/tools/testing/selftests/livepatch/test-state.sh b/tools/testing/selftests/livepatch/test-state.sh
new file mode 100755
index 000000000000..dc2908c22c26
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test-state.sh
@@ -0,0 +1,180 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2019 SUSE
+
+. $(dirname $0)/functions.sh
+
+MOD_LIVEPATCH=test_klp_state
+MOD_LIVEPATCH2=test_klp_state2
+MOD_LIVEPATCH3=test_klp_state3
+
+set_dynamic_debug
+
+
+# TEST: Loading and removing a module that modifies the system state
+
+echo -n "TEST: system state modification ... "
+dmesg -C
+
+load_lp $MOD_LIVEPATCH
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+
+check_result "% modprobe $MOD_LIVEPATCH
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+$MOD_LIVEPATCH: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+$MOD_LIVEPATCH: post_patch_callback: vmlinux
+$MOD_LIVEPATCH: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_LIVEPATCH': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+$MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
+$MOD_LIVEPATCH: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+$MOD_LIVEPATCH: post_unpatch_callback: vmlinux
+$MOD_LIVEPATCH: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH"
+
+
+# TEST: Take over system state change by a cumulative patch
+
+echo -n "TEST: taking over system state modification ... "
+dmesg -C
+
+load_lp $MOD_LIVEPATCH
+load_lp $MOD_LIVEPATCH2
+unload_lp $MOD_LIVEPATCH
+disable_lp $MOD_LIVEPATCH2
+unload_lp $MOD_LIVEPATCH2
+
+check_result "% modprobe $MOD_LIVEPATCH
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+$MOD_LIVEPATCH: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+$MOD_LIVEPATCH: post_patch_callback: vmlinux
+$MOD_LIVEPATCH: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_LIVEPATCH': patching complete
+% modprobe $MOD_LIVEPATCH2
+livepatch: enabling patch '$MOD_LIVEPATCH2'
+livepatch: '$MOD_LIVEPATCH2': initializing patching transition
+$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH2: allocate_loglevel_state: space to store console_loglevel already allocated
+livepatch: '$MOD_LIVEPATCH2': starting patching transition
+livepatch: '$MOD_LIVEPATCH2': completing patching transition
+$MOD_LIVEPATCH2: post_patch_callback: vmlinux
+$MOD_LIVEPATCH2: fix_console_loglevel: taking over the console_loglevel change
+livepatch: '$MOD_LIVEPATCH2': patching complete
+% rmmod $MOD_LIVEPATCH
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
+$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
+$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_LIVEPATCH2': unpatching complete
+% rmmod $MOD_LIVEPATCH2"
+
+
+# TEST: Take over system state change by a cumulative patch
+
+echo -n "TEST: compatible cumulative livepatches ... "
+dmesg -C
+
+load_lp $MOD_LIVEPATCH2
+load_lp $MOD_LIVEPATCH3
+unload_lp $MOD_LIVEPATCH2
+load_lp $MOD_LIVEPATCH2
+disable_lp $MOD_LIVEPATCH2
+unload_lp $MOD_LIVEPATCH2
+unload_lp $MOD_LIVEPATCH3
+
+check_result "% modprobe $MOD_LIVEPATCH2
+livepatch: enabling patch '$MOD_LIVEPATCH2'
+livepatch: '$MOD_LIVEPATCH2': initializing patching transition
+$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH2: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_LIVEPATCH2': starting patching transition
+livepatch: '$MOD_LIVEPATCH2': completing patching transition
+$MOD_LIVEPATCH2: post_patch_callback: vmlinux
+$MOD_LIVEPATCH2: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_LIVEPATCH2': patching complete
+% modprobe $MOD_LIVEPATCH3
+livepatch: enabling patch '$MOD_LIVEPATCH3'
+livepatch: '$MOD_LIVEPATCH3': initializing patching transition
+$MOD_LIVEPATCH3: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH3: allocate_loglevel_state: space to store console_loglevel already allocated
+livepatch: '$MOD_LIVEPATCH3': starting patching transition
+livepatch: '$MOD_LIVEPATCH3': completing patching transition
+$MOD_LIVEPATCH3: post_patch_callback: vmlinux
+$MOD_LIVEPATCH3: fix_console_loglevel: taking over the console_loglevel change
+livepatch: '$MOD_LIVEPATCH3': patching complete
+% rmmod $MOD_LIVEPATCH2
+% modprobe $MOD_LIVEPATCH2
+livepatch: enabling patch '$MOD_LIVEPATCH2'
+livepatch: '$MOD_LIVEPATCH2': initializing patching transition
+$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH2: allocate_loglevel_state: space to store console_loglevel already allocated
+livepatch: '$MOD_LIVEPATCH2': starting patching transition
+livepatch: '$MOD_LIVEPATCH2': completing patching transition
+$MOD_LIVEPATCH2: post_patch_callback: vmlinux
+$MOD_LIVEPATCH2: fix_console_loglevel: taking over the console_loglevel change
+livepatch: '$MOD_LIVEPATCH2': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
+$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
+$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_LIVEPATCH2': unpatching complete
+% rmmod $MOD_LIVEPATCH2
+% rmmod $MOD_LIVEPATCH3"
+
+
+# TEST: Failure caused by incompatible cumulative livepatches
+
+echo -n "TEST: incompatible cumulative livepatches ... "
+dmesg -C
+
+load_lp $MOD_LIVEPATCH2
+load_failing_mod $MOD_LIVEPATCH
+disable_lp $MOD_LIVEPATCH2
+unload_lp $MOD_LIVEPATCH2
+
+check_result "% modprobe $MOD_LIVEPATCH2
+livepatch: enabling patch '$MOD_LIVEPATCH2'
+livepatch: '$MOD_LIVEPATCH2': initializing patching transition
+$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
+$MOD_LIVEPATCH2: allocate_loglevel_state: allocating space to store console_loglevel
+livepatch: '$MOD_LIVEPATCH2': starting patching transition
+livepatch: '$MOD_LIVEPATCH2': completing patching transition
+$MOD_LIVEPATCH2: post_patch_callback: vmlinux
+$MOD_LIVEPATCH2: fix_console_loglevel: fixing console_loglevel
+livepatch: '$MOD_LIVEPATCH2': patching complete
+% modprobe $MOD_LIVEPATCH
+livepatch: Livepatch patch ($MOD_LIVEPATCH) is not compatible with the already installed livepatches.
+modprobe: ERROR: could not insert '$MOD_LIVEPATCH': Invalid argument
+% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH2/enabled
+livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
+$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: restore_console_loglevel: restoring console_loglevel
+livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
+$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
+$MOD_LIVEPATCH2: free_loglevel_state: freeing space for the stored console_loglevel
+livepatch: '$MOD_LIVEPATCH2': unpatching complete
+% rmmod $MOD_LIVEPATCH2"
+
+exit 0