v4.19.13 snapshot.
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
new file mode 100644
index 0000000..82d5842
--- /dev/null
+++ b/kernel/livepatch/patch.c
@@ -0,0 +1,277 @@
+/*
+ * patch.c - livepatch patching functions
+ *
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ * Copyright (C) 2014 SUSE
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@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/livepatch.h>
+#include <linux/list.h>
+#include <linux/ftrace.h>
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <linux/bug.h>
+#include <linux/printk.h>
+#include "core.h"
+#include "patch.h"
+#include "transition.h"
+
+static LIST_HEAD(klp_ops);
+
+struct klp_ops *klp_find_ops(unsigned long old_addr)
+{
+ struct klp_ops *ops;
+ struct klp_func *func;
+
+ list_for_each_entry(ops, &klp_ops, node) {
+ func = list_first_entry(&ops->func_stack, struct klp_func,
+ stack_node);
+ if (func->old_addr == old_addr)
+ return ops;
+ }
+
+ return NULL;
+}
+
+static void notrace klp_ftrace_handler(unsigned long ip,
+ unsigned long parent_ip,
+ struct ftrace_ops *fops,
+ struct pt_regs *regs)
+{
+ struct klp_ops *ops;
+ struct klp_func *func;
+ int patch_state;
+
+ ops = container_of(fops, struct klp_ops, fops);
+
+ /*
+ * A variant of synchronize_sched() is used to allow patching functions
+ * where RCU is not watching, see klp_synchronize_transition().
+ */
+ preempt_disable_notrace();
+
+ func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
+ stack_node);
+
+ /*
+ * func should never be NULL because preemption should be disabled here
+ * and unregister_ftrace_function() does the equivalent of a
+ * synchronize_sched() before the func_stack removal.
+ */
+ if (WARN_ON_ONCE(!func))
+ goto unlock;
+
+ /*
+ * In the enable path, enforce the order of the ops->func_stack and
+ * func->transition reads. The corresponding write barrier is in
+ * __klp_enable_patch().
+ *
+ * (Note that this barrier technically isn't needed in the disable
+ * path. In the rare case where klp_update_patch_state() runs before
+ * this handler, its TIF_PATCH_PENDING read and this func->transition
+ * read need to be ordered. But klp_update_patch_state() already
+ * enforces that.)
+ */
+ smp_rmb();
+
+ if (unlikely(func->transition)) {
+
+ /*
+ * Enforce the order of the func->transition and
+ * current->patch_state reads. Otherwise we could read an
+ * out-of-date task state and pick the wrong function. The
+ * corresponding write barrier is in klp_init_transition().
+ */
+ smp_rmb();
+
+ patch_state = current->patch_state;
+
+ WARN_ON_ONCE(patch_state == KLP_UNDEFINED);
+
+ if (patch_state == KLP_UNPATCHED) {
+ /*
+ * Use the previously patched version of the function.
+ * If no previous patches exist, continue with the
+ * original function.
+ */
+ func = list_entry_rcu(func->stack_node.next,
+ struct klp_func, stack_node);
+
+ if (&func->stack_node == &ops->func_stack)
+ goto unlock;
+ }
+ }
+
+ klp_arch_set_pc(regs, (unsigned long)func->new_func);
+unlock:
+ preempt_enable_notrace();
+}
+
+/*
+ * Convert a function address into the appropriate ftrace location.
+ *
+ * Usually this is just the address of the function, but on some architectures
+ * it's more complicated so allow them to provide a custom behaviour.
+ */
+#ifndef klp_get_ftrace_location
+static unsigned long klp_get_ftrace_location(unsigned long faddr)
+{
+ return faddr;
+}
+#endif
+
+static void klp_unpatch_func(struct klp_func *func)
+{
+ struct klp_ops *ops;
+
+ if (WARN_ON(!func->patched))
+ return;
+ if (WARN_ON(!func->old_addr))
+ return;
+
+ ops = klp_find_ops(func->old_addr);
+ if (WARN_ON(!ops))
+ return;
+
+ if (list_is_singular(&ops->func_stack)) {
+ unsigned long ftrace_loc;
+
+ ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ if (WARN_ON(!ftrace_loc))
+ return;
+
+ WARN_ON(unregister_ftrace_function(&ops->fops));
+ WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0));
+
+ list_del_rcu(&func->stack_node);
+ list_del(&ops->node);
+ kfree(ops);
+ } else {
+ list_del_rcu(&func->stack_node);
+ }
+
+ func->patched = false;
+}
+
+static int klp_patch_func(struct klp_func *func)
+{
+ struct klp_ops *ops;
+ int ret;
+
+ if (WARN_ON(!func->old_addr))
+ return -EINVAL;
+
+ if (WARN_ON(func->patched))
+ return -EINVAL;
+
+ ops = klp_find_ops(func->old_addr);
+ if (!ops) {
+ unsigned long ftrace_loc;
+
+ ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ if (!ftrace_loc) {
+ pr_err("failed to find location for function '%s'\n",
+ func->old_name);
+ return -EINVAL;
+ }
+
+ ops = kzalloc(sizeof(*ops), GFP_KERNEL);
+ if (!ops)
+ return -ENOMEM;
+
+ ops->fops.func = klp_ftrace_handler;
+ ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
+ FTRACE_OPS_FL_DYNAMIC |
+ FTRACE_OPS_FL_IPMODIFY;
+
+ list_add(&ops->node, &klp_ops);
+
+ INIT_LIST_HEAD(&ops->func_stack);
+ list_add_rcu(&func->stack_node, &ops->func_stack);
+
+ ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0);
+ if (ret) {
+ pr_err("failed to set ftrace filter for function '%s' (%d)\n",
+ func->old_name, ret);
+ goto err;
+ }
+
+ ret = register_ftrace_function(&ops->fops);
+ if (ret) {
+ pr_err("failed to register ftrace handler for function '%s' (%d)\n",
+ func->old_name, ret);
+ ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0);
+ goto err;
+ }
+
+
+ } else {
+ list_add_rcu(&func->stack_node, &ops->func_stack);
+ }
+
+ func->patched = true;
+
+ return 0;
+
+err:
+ list_del_rcu(&func->stack_node);
+ list_del(&ops->node);
+ kfree(ops);
+ return ret;
+}
+
+void klp_unpatch_object(struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ klp_for_each_func(obj, func)
+ if (func->patched)
+ klp_unpatch_func(func);
+
+ obj->patched = false;
+}
+
+int klp_patch_object(struct klp_object *obj)
+{
+ struct klp_func *func;
+ int ret;
+
+ if (WARN_ON(obj->patched))
+ return -EINVAL;
+
+ klp_for_each_func(obj, func) {
+ ret = klp_patch_func(func);
+ if (ret) {
+ klp_unpatch_object(obj);
+ return ret;
+ }
+ }
+ obj->patched = true;
+
+ return 0;
+}
+
+void klp_unpatch_objects(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+
+ klp_for_each_object(patch, obj)
+ if (obj->patched)
+ klp_unpatch_object(obj);
+}