v4.19.13 snapshot.
diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c
new file mode 100644
index 0000000..83958c8
--- /dev/null
+++ b/kernel/livepatch/shadow.c
@@ -0,0 +1,311 @@
+/*
+ * shadow.c - Shadow Variables
+ *
+ * Copyright (C) 2014 Josh Poimboeuf <jpoimboe@redhat.com>
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ * 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/>.
+ */
+
+/**
+ * DOC: Shadow variable API concurrency notes:
+ *
+ * The shadow variable API provides a simple relationship between an
+ * <obj, id> pair and a pointer value. It is the responsibility of the
+ * caller to provide any mutual exclusion required of the shadow data.
+ *
+ * Once a shadow variable is attached to its parent object via the
+ * klp_shadow_*alloc() API calls, it is considered live: any subsequent
+ * call to klp_shadow_get() may then return the shadow variable's data
+ * pointer. Callers of klp_shadow_*alloc() should prepare shadow data
+ * accordingly.
+ *
+ * The klp_shadow_*alloc() API calls may allocate memory for new shadow
+ * variable structures. Their implementation does not call kmalloc
+ * inside any spinlocks, but API callers should pass GFP flags according
+ * to their specific needs.
+ *
+ * The klp_shadow_hash is an RCU-enabled hashtable and is safe against
+ * concurrent klp_shadow_free() and klp_shadow_get() operations.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hashtable.h>
+#include <linux/slab.h>
+#include <linux/livepatch.h>
+
+static DEFINE_HASHTABLE(klp_shadow_hash, 12);
+
+/*
+ * klp_shadow_lock provides exclusive access to the klp_shadow_hash and
+ * the shadow variables it references.
+ */
+static DEFINE_SPINLOCK(klp_shadow_lock);
+
+/**
+ * struct klp_shadow - shadow variable structure
+ * @node: klp_shadow_hash hash table node
+ * @rcu_head: RCU is used to safely free this structure
+ * @obj: pointer to parent object
+ * @id: data identifier
+ * @data: data area
+ */
+struct klp_shadow {
+ struct hlist_node node;
+ struct rcu_head rcu_head;
+ void *obj;
+ unsigned long id;
+ char data[];
+};
+
+/**
+ * klp_shadow_match() - verify a shadow variable matches given <obj, id>
+ * @shadow: shadow variable to match
+ * @obj: pointer to parent object
+ * @id: data identifier
+ *
+ * Return: true if the shadow variable matches.
+ */
+static inline bool klp_shadow_match(struct klp_shadow *shadow, void *obj,
+ unsigned long id)
+{
+ return shadow->obj == obj && shadow->id == id;
+}
+
+/**
+ * klp_shadow_get() - retrieve a shadow variable data pointer
+ * @obj: pointer to parent object
+ * @id: data identifier
+ *
+ * Return: the shadow variable data element, NULL on failure.
+ */
+void *klp_shadow_get(void *obj, unsigned long id)
+{
+ struct klp_shadow *shadow;
+
+ rcu_read_lock();
+
+ hash_for_each_possible_rcu(klp_shadow_hash, shadow, node,
+ (unsigned long)obj) {
+
+ if (klp_shadow_match(shadow, obj, id)) {
+ rcu_read_unlock();
+ return shadow->data;
+ }
+ }
+
+ rcu_read_unlock();
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(klp_shadow_get);
+
+static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id,
+ size_t size, gfp_t gfp_flags,
+ klp_shadow_ctor_t ctor, void *ctor_data,
+ bool warn_on_exist)
+{
+ struct klp_shadow *new_shadow;
+ void *shadow_data;
+ unsigned long flags;
+
+ /* Check if the shadow variable already exists */
+ shadow_data = klp_shadow_get(obj, id);
+ if (shadow_data)
+ goto exists;
+
+ /*
+ * Allocate a new shadow variable. Fill it with zeroes by default.
+ * More complex setting can be done by @ctor function. But it is
+ * called only when the buffer is really used (under klp_shadow_lock).
+ */
+ new_shadow = kzalloc(size + sizeof(*new_shadow), gfp_flags);
+ if (!new_shadow)
+ return NULL;
+
+ /* Look for <obj, id> again under the lock */
+ spin_lock_irqsave(&klp_shadow_lock, flags);
+ shadow_data = klp_shadow_get(obj, id);
+ if (unlikely(shadow_data)) {
+ /*
+ * Shadow variable was found, throw away speculative
+ * allocation.
+ */
+ spin_unlock_irqrestore(&klp_shadow_lock, flags);
+ kfree(new_shadow);
+ goto exists;
+ }
+
+ new_shadow->obj = obj;
+ new_shadow->id = id;
+
+ if (ctor) {
+ int err;
+
+ err = ctor(obj, new_shadow->data, ctor_data);
+ if (err) {
+ spin_unlock_irqrestore(&klp_shadow_lock, flags);
+ kfree(new_shadow);
+ pr_err("Failed to construct shadow variable <%p, %lx> (%d)\n",
+ obj, id, err);
+ return NULL;
+ }
+ }
+
+ /* No <obj, id> found, so attach the newly allocated one */
+ hash_add_rcu(klp_shadow_hash, &new_shadow->node,
+ (unsigned long)new_shadow->obj);
+ spin_unlock_irqrestore(&klp_shadow_lock, flags);
+
+ return new_shadow->data;
+
+exists:
+ if (warn_on_exist) {
+ WARN(1, "Duplicate shadow variable <%p, %lx>\n", obj, id);
+ return NULL;
+ }
+
+ return shadow_data;
+}
+
+/**
+ * klp_shadow_alloc() - allocate and add a new shadow variable
+ * @obj: pointer to parent object
+ * @id: data identifier
+ * @size: size of attached data
+ * @gfp_flags: GFP mask for allocation
+ * @ctor: custom constructor to initialize the shadow data (optional)
+ * @ctor_data: pointer to any data needed by @ctor (optional)
+ *
+ * Allocates @size bytes for new shadow variable data using @gfp_flags.
+ * The data are zeroed by default. They are further initialized by @ctor
+ * function if it is not NULL. The new shadow variable is then added
+ * to the global hashtable.
+ *
+ * If an existing <obj, id> shadow variable can be found, this routine will
+ * issue a WARN, exit early and return NULL.
+ *
+ * This function guarantees that the constructor function is called only when
+ * the variable did not exist before. The cost is that @ctor is called
+ * in atomic context under a spin lock.
+ *
+ * Return: the shadow variable data element, NULL on duplicate or
+ * failure.
+ */
+void *klp_shadow_alloc(void *obj, unsigned long id,
+ size_t size, gfp_t gfp_flags,
+ klp_shadow_ctor_t ctor, void *ctor_data)
+{
+ return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
+ ctor, ctor_data, true);
+}
+EXPORT_SYMBOL_GPL(klp_shadow_alloc);
+
+/**
+ * klp_shadow_get_or_alloc() - get existing or allocate a new shadow variable
+ * @obj: pointer to parent object
+ * @id: data identifier
+ * @size: size of attached data
+ * @gfp_flags: GFP mask for allocation
+ * @ctor: custom constructor to initialize the shadow data (optional)
+ * @ctor_data: pointer to any data needed by @ctor (optional)
+ *
+ * Returns a pointer to existing shadow data if an <obj, id> shadow
+ * variable is already present. Otherwise, it creates a new shadow
+ * variable like klp_shadow_alloc().
+ *
+ * This function guarantees that only one shadow variable exists with the given
+ * @id for the given @obj. It also guarantees that the constructor function
+ * will be called only when the variable did not exist before. The cost is
+ * that @ctor is called in atomic context under a spin lock.
+ *
+ * Return: the shadow variable data element, NULL on failure.
+ */
+void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
+ size_t size, gfp_t gfp_flags,
+ klp_shadow_ctor_t ctor, void *ctor_data)
+{
+ return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
+ ctor, ctor_data, false);
+}
+EXPORT_SYMBOL_GPL(klp_shadow_get_or_alloc);
+
+static void klp_shadow_free_struct(struct klp_shadow *shadow,
+ klp_shadow_dtor_t dtor)
+{
+ hash_del_rcu(&shadow->node);
+ if (dtor)
+ dtor(shadow->obj, shadow->data);
+ kfree_rcu(shadow, rcu_head);
+}
+
+/**
+ * klp_shadow_free() - detach and free a <obj, id> shadow variable
+ * @obj: pointer to parent object
+ * @id: data identifier
+ * @dtor: custom callback that can be used to unregister the variable
+ * and/or free data that the shadow variable points to (optional)
+ *
+ * This function releases the memory for this <obj, id> shadow variable
+ * instance, callers should stop referencing it accordingly.
+ */
+void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
+{
+ struct klp_shadow *shadow;
+ unsigned long flags;
+
+ spin_lock_irqsave(&klp_shadow_lock, flags);
+
+ /* Delete <obj, id> from hash */
+ hash_for_each_possible(klp_shadow_hash, shadow, node,
+ (unsigned long)obj) {
+
+ if (klp_shadow_match(shadow, obj, id)) {
+ klp_shadow_free_struct(shadow, dtor);
+ break;
+ }
+ }
+
+ spin_unlock_irqrestore(&klp_shadow_lock, flags);
+}
+EXPORT_SYMBOL_GPL(klp_shadow_free);
+
+/**
+ * klp_shadow_free_all() - detach and free all <*, id> shadow variables
+ * @id: data identifier
+ * @dtor: custom callback that can be used to unregister the variable
+ * and/or free data that the shadow variable points to (optional)
+ *
+ * This function releases the memory for all <*, id> shadow variable
+ * instances, callers should stop referencing them accordingly.
+ */
+void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
+{
+ struct klp_shadow *shadow;
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&klp_shadow_lock, flags);
+
+ /* Delete all <*, id> from hash */
+ hash_for_each(klp_shadow_hash, i, shadow, node) {
+ if (klp_shadow_match(shadow, shadow->obj, id))
+ klp_shadow_free_struct(shadow, dtor);
+ }
+
+ spin_unlock_irqrestore(&klp_shadow_lock, flags);
+}
+EXPORT_SYMBOL_GPL(klp_shadow_free_all);