v4.19.13 snapshot.
diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile
new file mode 100644
index 0000000..2472ce3
--- /dev/null
+++ b/samples/livepatch/Makefile
@@ -0,0 +1,7 @@
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-sample.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-shadow-mod.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-shadow-fix1.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-shadow-fix2.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-demo.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-mod.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-busymod.o
diff --git a/samples/livepatch/livepatch-callbacks-busymod.c b/samples/livepatch/livepatch-callbacks-busymod.c
new file mode 100644
index 0000000..80d06e1
--- /dev/null
+++ b/samples/livepatch/livepatch-callbacks-busymod.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-callbacks-busymod.c - (un)patching callbacks demo support module
+ *
+ *
+ * Purpose
+ * -------
+ *
+ * Simple module to demonstrate livepatch (un)patching callbacks.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * This module is not intended to be standalone. See the "Usage"
+ * section of livepatch-callbacks-mod.c.
+ */
+
+#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 livepatch_callbacks_mod_init(void)
+{
+ pr_info("%s\n", __func__);
+ schedule_delayed_work(&work,
+ msecs_to_jiffies(1000 * 0));
+ return 0;
+}
+
+static void livepatch_callbacks_mod_exit(void)
+{
+ cancel_delayed_work_sync(&work);
+ pr_info("%s\n", __func__);
+}
+
+module_init(livepatch_callbacks_mod_init);
+module_exit(livepatch_callbacks_mod_exit);
+MODULE_LICENSE("GPL");
diff --git a/samples/livepatch/livepatch-callbacks-demo.c b/samples/livepatch/livepatch-callbacks-demo.c
new file mode 100644
index 0000000..72f9e6d
--- /dev/null
+++ b/samples/livepatch/livepatch-callbacks-demo.c
@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-callbacks-demo.c - (un)patching callbacks livepatch demo
+ *
+ *
+ * Purpose
+ * -------
+ *
+ * Demonstration of registering livepatch (un)patching callbacks.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * Step 1 - load the simple module
+ *
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ *
+ *
+ * Step 2 - load the demonstration livepatch (with callbacks)
+ *
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ *
+ * Step 3 - cleanup
+ *
+ * echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
+ * rmmod livepatch_callbacks_demo
+ * rmmod livepatch_callbacks_mod
+ *
+ * Watch dmesg output to see livepatch enablement, callback execution
+ * and patching operations for both vmlinux and module targets.
+ *
+ * NOTE: swap the insmod order of livepatch-callbacks-mod.ko and
+ * livepatch-callbacks-demo.ko to observe what happens when a
+ * target module is loaded after a livepatch with callbacks.
+ *
+ * NOTE: 'pre_patch_ret' is a module parameter that sets the pre-patch
+ * callback return status. Try setting up a non-zero status
+ * such as -19 (-ENODEV):
+ *
+ * # Load demo livepatch, vmlinux is patched
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ * # Setup next pre-patch callback to return -ENODEV
+ * echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
+ *
+ * # Module loader refuses to load the target module
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ * insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko: No such device
+ *
+ * NOTE: There is a second target module,
+ * livepatch-callbacks-busymod.ko, available for experimenting
+ * with livepatch (un)patch callbacks. This module contains
+ * a 'sleep_secs' parameter that parks the module on one of the
+ * functions that the livepatch demo module wants to patch.
+ * Modifying this value and tweaking the order of module loads can
+ * effectively demonstrate stalled patch transitions:
+ *
+ * # Load a target module, let it park on 'busymod_work_func' for
+ * # thirty seconds
+ * insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
+ *
+ * # Meanwhile load the livepatch
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ * # ... then load and unload another target module while the
+ * # transition is in progress
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ * rmmod samples/livepatch/livepatch-callbacks-mod.ko
+ *
+ * # Finally cleanup
+ * echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
+ * rmmod samples/livepatch/livepatch-callbacks-demo.ko
+ */
+
+#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 = "livepatch_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 = "livepatch_callbacks_busymod",
+ .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 livepatch_callbacks_demo_init(void)
+{
+ int ret;
+
+ ret = klp_register_patch(&patch);
+ if (ret)
+ return ret;
+ ret = klp_enable_patch(&patch);
+ if (ret) {
+ WARN_ON(klp_unregister_patch(&patch));
+ return ret;
+ }
+ return 0;
+}
+
+static void livepatch_callbacks_demo_exit(void)
+{
+ WARN_ON(klp_unregister_patch(&patch));
+}
+
+module_init(livepatch_callbacks_demo_init);
+module_exit(livepatch_callbacks_demo_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-callbacks-mod.c b/samples/livepatch/livepatch-callbacks-mod.c
new file mode 100644
index 0000000..e610ce2
--- /dev/null
+++ b/samples/livepatch/livepatch-callbacks-mod.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-callbacks-mod.c - (un)patching callbacks demo support module
+ *
+ *
+ * Purpose
+ * -------
+ *
+ * Simple module to demonstrate livepatch (un)patching callbacks.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * This module is not intended to be standalone. See the "Usage"
+ * section of livepatch-callbacks-demo.c.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+static int livepatch_callbacks_mod_init(void)
+{
+ pr_info("%s\n", __func__);
+ return 0;
+}
+
+static void livepatch_callbacks_mod_exit(void)
+{
+ pr_info("%s\n", __func__);
+}
+
+module_init(livepatch_callbacks_mod_init);
+module_exit(livepatch_callbacks_mod_exit);
+MODULE_LICENSE("GPL");
diff --git a/samples/livepatch/livepatch-sample.c b/samples/livepatch/livepatch-sample.c
new file mode 100644
index 0000000..2d554dd
--- /dev/null
+++ b/samples/livepatch/livepatch-sample.c
@@ -0,0 +1,93 @@
+/*
+ * livepatch-sample.c - Kernel Live Patching Sample Module
+ *
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+/*
+ * This (dumb) live patch overrides the function that prints the
+ * kernel boot cmdline when /proc/cmdline is read.
+ *
+ * Example:
+ *
+ * $ cat /proc/cmdline
+ * <your cmdline>
+ *
+ * $ insmod livepatch-sample.ko
+ * $ cat /proc/cmdline
+ * this has been live patched
+ *
+ * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
+ * $ cat /proc/cmdline
+ * <your cmdline>
+ */
+
+#include <linux/seq_file.h>
+static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%s\n", "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 livepatch_init(void)
+{
+ int ret;
+
+ ret = klp_register_patch(&patch);
+ if (ret)
+ return ret;
+ ret = klp_enable_patch(&patch);
+ if (ret) {
+ WARN_ON(klp_unregister_patch(&patch));
+ return ret;
+ }
+ return 0;
+}
+
+static void livepatch_exit(void)
+{
+ WARN_ON(klp_unregister_patch(&patch));
+}
+
+module_init(livepatch_init);
+module_exit(livepatch_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
new file mode 100644
index 0000000..49b1355
--- /dev/null
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-shadow-fix1.c - Shadow variables, livepatch demo
+ *
+ * Purpose
+ * -------
+ *
+ * Fixes the memory leak introduced in livepatch-shadow-mod through the
+ * use of a shadow variable. This fix demonstrates the "extending" of
+ * short-lived data structures by patching its allocation and release
+ * functions.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * This module is not intended to be standalone. See the "Usage"
+ * section of livepatch-shadow-mod.c.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include <linux/slab.h>
+
+/* Shadow variable enums */
+#define SV_LEAK 1
+
+/* Allocate new dummies every second */
+#define ALLOC_PERIOD 1
+/* Check for expired dummies after a few new ones have been allocated */
+#define CLEANUP_PERIOD (3 * ALLOC_PERIOD)
+/* Dummies expire after a few cleanup instances */
+#define EXPIRE_PERIOD (4 * CLEANUP_PERIOD)
+
+struct dummy {
+ struct list_head list;
+ unsigned long jiffies_expire;
+};
+
+/*
+ * The constructor makes more sense together with klp_shadow_get_or_alloc().
+ * In this example, it would be safe to assign the pointer also to the shadow
+ * variable returned by klp_shadow_alloc(). But we wanted to show the more
+ * complicated use of the API.
+ */
+static int shadow_leak_ctor(void *obj, void *shadow_data, void *ctor_data)
+{
+ void **shadow_leak = shadow_data;
+ void *leak = ctor_data;
+
+ *shadow_leak = leak;
+ return 0;
+}
+
+struct dummy *livepatch_fix1_dummy_alloc(void)
+{
+ struct dummy *d;
+ void *leak;
+
+ d = kzalloc(sizeof(*d), GFP_KERNEL);
+ if (!d)
+ return NULL;
+
+ d->jiffies_expire = jiffies +
+ msecs_to_jiffies(1000 * EXPIRE_PERIOD);
+
+ /*
+ * Patch: save the extra memory location into a SV_LEAK shadow
+ * variable. A patched dummy_free routine can later fetch this
+ * pointer to handle resource release.
+ */
+ leak = kzalloc(sizeof(int), GFP_KERNEL);
+ klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
+ shadow_leak_ctor, leak);
+
+ pr_info("%s: dummy @ %p, expires @ %lx\n",
+ __func__, d, d->jiffies_expire);
+
+ return d;
+}
+
+static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
+{
+ void *d = obj;
+ void **shadow_leak = shadow_data;
+
+ kfree(*shadow_leak);
+ pr_info("%s: dummy @ %p, prevented leak @ %p\n",
+ __func__, d, *shadow_leak);
+}
+
+void livepatch_fix1_dummy_free(struct dummy *d)
+{
+ void **shadow_leak;
+
+ /*
+ * Patch: fetch the saved SV_LEAK shadow variable, detach and
+ * free it. Note: handle cases where this shadow variable does
+ * not exist (ie, dummy structures allocated before this livepatch
+ * was loaded.)
+ */
+ shadow_leak = klp_shadow_get(d, SV_LEAK);
+ if (shadow_leak)
+ klp_shadow_free(d, SV_LEAK, livepatch_fix1_dummy_leak_dtor);
+ else
+ pr_info("%s: dummy @ %p leaked!\n", __func__, d);
+
+ kfree(d);
+}
+
+static struct klp_func funcs[] = {
+ {
+ .old_name = "dummy_alloc",
+ .new_func = livepatch_fix1_dummy_alloc,
+ },
+ {
+ .old_name = "dummy_free",
+ .new_func = livepatch_fix1_dummy_free,
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ .name = "livepatch_shadow_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int livepatch_shadow_fix1_init(void)
+{
+ int ret;
+
+ ret = klp_register_patch(&patch);
+ if (ret)
+ return ret;
+ ret = klp_enable_patch(&patch);
+ if (ret) {
+ WARN_ON(klp_unregister_patch(&patch));
+ return ret;
+ }
+ return 0;
+}
+
+static void livepatch_shadow_fix1_exit(void)
+{
+ /* Cleanup any existing SV_LEAK shadow variables */
+ klp_shadow_free_all(SV_LEAK, livepatch_fix1_dummy_leak_dtor);
+
+ WARN_ON(klp_unregister_patch(&patch));
+}
+
+module_init(livepatch_shadow_fix1_init);
+module_exit(livepatch_shadow_fix1_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c
new file mode 100644
index 0000000..b34c7bf
--- /dev/null
+++ b/samples/livepatch/livepatch-shadow-fix2.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-shadow-fix2.c - Shadow variables, livepatch demo
+ *
+ * Purpose
+ * -------
+ *
+ * Adds functionality to livepatch-shadow-mod's in-flight data
+ * structures through a shadow variable. The livepatch patches a
+ * routine that periodically inspects data structures, incrementing a
+ * per-data-structure counter, creating the counter if needed.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * This module is not intended to be standalone. See the "Usage"
+ * section of livepatch-shadow-mod.c.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include <linux/slab.h>
+
+/* Shadow variable enums */
+#define SV_LEAK 1
+#define SV_COUNTER 2
+
+struct dummy {
+ struct list_head list;
+ unsigned long jiffies_expire;
+};
+
+bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies)
+{
+ int *shadow_count;
+
+ /*
+ * Patch: handle in-flight dummy structures, if they do not
+ * already have a SV_COUNTER shadow variable, then attach a
+ * new one.
+ */
+ shadow_count = klp_shadow_get_or_alloc(d, SV_COUNTER,
+ sizeof(*shadow_count), GFP_NOWAIT,
+ NULL, NULL);
+ if (shadow_count)
+ *shadow_count += 1;
+
+ return time_after(jiffies, d->jiffies_expire);
+}
+
+static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
+{
+ void *d = obj;
+ void **shadow_leak = shadow_data;
+
+ kfree(*shadow_leak);
+ pr_info("%s: dummy @ %p, prevented leak @ %p\n",
+ __func__, d, *shadow_leak);
+}
+
+void livepatch_fix2_dummy_free(struct dummy *d)
+{
+ void **shadow_leak;
+ int *shadow_count;
+
+ /* Patch: copy the memory leak patch from the fix1 module. */
+ shadow_leak = klp_shadow_get(d, SV_LEAK);
+ if (shadow_leak)
+ klp_shadow_free(d, SV_LEAK, livepatch_fix2_dummy_leak_dtor);
+ else
+ pr_info("%s: dummy @ %p leaked!\n", __func__, d);
+
+ /*
+ * Patch: fetch the SV_COUNTER shadow variable and display
+ * the final count. Detach the shadow variable.
+ */
+ shadow_count = klp_shadow_get(d, SV_COUNTER);
+ if (shadow_count) {
+ pr_info("%s: dummy @ %p, check counter = %d\n",
+ __func__, d, *shadow_count);
+ klp_shadow_free(d, SV_COUNTER, NULL);
+ }
+
+ kfree(d);
+}
+
+static struct klp_func funcs[] = {
+ {
+ .old_name = "dummy_check",
+ .new_func = livepatch_fix2_dummy_check,
+ },
+ {
+ .old_name = "dummy_free",
+ .new_func = livepatch_fix2_dummy_free,
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ .name = "livepatch_shadow_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int livepatch_shadow_fix2_init(void)
+{
+ int ret;
+
+ ret = klp_register_patch(&patch);
+ if (ret)
+ return ret;
+ ret = klp_enable_patch(&patch);
+ if (ret) {
+ WARN_ON(klp_unregister_patch(&patch));
+ return ret;
+ }
+ return 0;
+}
+
+static void livepatch_shadow_fix2_exit(void)
+{
+ /* Cleanup any existing SV_COUNTER shadow variables */
+ klp_shadow_free_all(SV_COUNTER, NULL);
+
+ WARN_ON(klp_unregister_patch(&patch));
+}
+
+module_init(livepatch_shadow_fix2_init);
+module_exit(livepatch_shadow_fix2_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c
new file mode 100644
index 0000000..4c54b25
--- /dev/null
+++ b/samples/livepatch/livepatch-shadow-mod.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * livepatch-shadow-mod.c - Shadow variables, buggy module demo
+ *
+ * Purpose
+ * -------
+ *
+ * As a demonstration of livepatch shadow variable API, this module
+ * introduces memory leak behavior that livepatch modules
+ * livepatch-shadow-fix1.ko and livepatch-shadow-fix2.ko correct and
+ * enhance.
+ *
+ * WARNING - even though the livepatch-shadow-fix modules patch the
+ * memory leak, please load these modules at your own risk -- some
+ * amount of memory may leaked before the bug is patched.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * Step 1 - Load the buggy demonstration module:
+ *
+ * insmod samples/livepatch/livepatch-shadow-mod.ko
+ *
+ * Watch dmesg output for a few moments to see new dummy being allocated
+ * and a periodic cleanup check. (Note: a small amount of memory is
+ * being leaked.)
+ *
+ *
+ * Step 2 - Load livepatch fix1:
+ *
+ * insmod samples/livepatch/livepatch-shadow-fix1.ko
+ *
+ * Continue watching dmesg and note that now livepatch_fix1_dummy_free()
+ * and livepatch_fix1_dummy_alloc() are logging messages about leaked
+ * memory and eventually leaks prevented.
+ *
+ *
+ * Step 3 - Load livepatch fix2 (on top of fix1):
+ *
+ * insmod samples/livepatch/livepatch-shadow-fix2.ko
+ *
+ * This module extends functionality through shadow variables, as a new
+ * "check" counter is added to the dummy structure. Periodic dmesg
+ * messages will log these as dummies are cleaned up.
+ *
+ *
+ * Step 4 - Cleanup
+ *
+ * Unwind the demonstration by disabling the livepatch fix modules, then
+ * removing them and the demo module:
+ *
+ * echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix2/enabled
+ * echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix1/enabled
+ * rmmod livepatch-shadow-fix2
+ * rmmod livepatch-shadow-fix1
+ * rmmod livepatch-shadow-mod
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/workqueue.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Buggy module for shadow variable demo");
+
+/* Allocate new dummies every second */
+#define ALLOC_PERIOD 1
+/* Check for expired dummies after a few new ones have been allocated */
+#define CLEANUP_PERIOD (3 * ALLOC_PERIOD)
+/* Dummies expire after a few cleanup instances */
+#define EXPIRE_PERIOD (4 * CLEANUP_PERIOD)
+
+/*
+ * Keep a list of all the dummies so we can clean up any residual ones
+ * on module exit
+ */
+LIST_HEAD(dummy_list);
+DEFINE_MUTEX(dummy_list_mutex);
+
+struct dummy {
+ struct list_head list;
+ unsigned long jiffies_expire;
+};
+
+noinline struct dummy *dummy_alloc(void)
+{
+ struct dummy *d;
+ void *leak;
+
+ d = kzalloc(sizeof(*d), GFP_KERNEL);
+ if (!d)
+ return NULL;
+
+ d->jiffies_expire = jiffies +
+ msecs_to_jiffies(1000 * EXPIRE_PERIOD);
+
+ /* Oops, forgot to save leak! */
+ leak = kzalloc(sizeof(int), GFP_KERNEL);
+
+ pr_info("%s: dummy @ %p, expires @ %lx\n",
+ __func__, d, d->jiffies_expire);
+
+ return d;
+}
+
+noinline void dummy_free(struct dummy *d)
+{
+ pr_info("%s: dummy @ %p, expired = %lx\n",
+ __func__, d, d->jiffies_expire);
+
+ kfree(d);
+}
+
+noinline bool dummy_check(struct dummy *d, unsigned long jiffies)
+{
+ return time_after(jiffies, d->jiffies_expire);
+}
+
+/*
+ * alloc_work_func: allocates new dummy structures, allocates additional
+ * memory, aptly named "leak", but doesn't keep
+ * permanent record of it.
+ */
+
+static void alloc_work_func(struct work_struct *work);
+static DECLARE_DELAYED_WORK(alloc_dwork, alloc_work_func);
+
+static void alloc_work_func(struct work_struct *work)
+{
+ struct dummy *d;
+
+ d = dummy_alloc();
+ if (!d)
+ return;
+
+ mutex_lock(&dummy_list_mutex);
+ list_add(&d->list, &dummy_list);
+ mutex_unlock(&dummy_list_mutex);
+
+ schedule_delayed_work(&alloc_dwork,
+ msecs_to_jiffies(1000 * ALLOC_PERIOD));
+}
+
+/*
+ * cleanup_work_func: frees dummy structures. Without knownledge of
+ * "leak", it leaks the additional memory that
+ * alloc_work_func created.
+ */
+
+static void cleanup_work_func(struct work_struct *work);
+static DECLARE_DELAYED_WORK(cleanup_dwork, cleanup_work_func);
+
+static void cleanup_work_func(struct work_struct *work)
+{
+ struct dummy *d, *tmp;
+ unsigned long j;
+
+ j = jiffies;
+ pr_info("%s: jiffies = %lx\n", __func__, j);
+
+ mutex_lock(&dummy_list_mutex);
+ list_for_each_entry_safe(d, tmp, &dummy_list, list) {
+
+ /* Kick out and free any expired dummies */
+ if (dummy_check(d, j)) {
+ list_del(&d->list);
+ dummy_free(d);
+ }
+ }
+ mutex_unlock(&dummy_list_mutex);
+
+ schedule_delayed_work(&cleanup_dwork,
+ msecs_to_jiffies(1000 * CLEANUP_PERIOD));
+}
+
+static int livepatch_shadow_mod_init(void)
+{
+ schedule_delayed_work(&alloc_dwork,
+ msecs_to_jiffies(1000 * ALLOC_PERIOD));
+ schedule_delayed_work(&cleanup_dwork,
+ msecs_to_jiffies(1000 * CLEANUP_PERIOD));
+
+ return 0;
+}
+
+static void livepatch_shadow_mod_exit(void)
+{
+ struct dummy *d, *tmp;
+
+ /* Wait for any dummies at work */
+ cancel_delayed_work_sync(&alloc_dwork);
+ cancel_delayed_work_sync(&cleanup_dwork);
+
+ /* Cleanup residual dummies */
+ list_for_each_entry_safe(d, tmp, &dummy_list, list) {
+ list_del(&d->list);
+ dummy_free(d);
+ }
+}
+
+module_init(livepatch_shadow_mod_init);
+module_exit(livepatch_shadow_mod_exit);