livepatch: move patching functions into patch.c
Move functions related to the actual patching of functions and objects into a new patch.c file. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Josh Poimboeuf
Jiri Kosina
parent
aa82dc3e00
commit
c349cdcaba
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@ -1,3 +1,3 @@
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obj-$(CONFIG_LIVEPATCH) += livepatch.o
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livepatch-objs := core.o
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livepatch-objs := core.o patch.o
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@ -24,32 +24,13 @@
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/ftrace.h>
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#include <linux/list.h>
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#include <linux/kallsyms.h>
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#include <linux/livepatch.h>
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#include <linux/elf.h>
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#include <linux/moduleloader.h>
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#include <asm/cacheflush.h>
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/**
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* struct klp_ops - structure for tracking registered ftrace ops structs
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*
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* A single ftrace_ops is shared between all enabled replacement functions
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* (klp_func structs) which have the same old_addr. This allows the switch
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* between function versions to happen instantaneously by updating the klp_ops
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* struct's func_stack list. The winner is the klp_func at the top of the
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* func_stack (front of the list).
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*
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* @node: node for the global klp_ops list
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* @func_stack: list head for the stack of klp_func's (active func is on top)
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* @fops: registered ftrace ops struct
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*/
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struct klp_ops {
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struct list_head node;
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struct list_head func_stack;
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struct ftrace_ops fops;
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};
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#include "patch.h"
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/*
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* The klp_mutex protects the global lists and state transitions of any
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@ -60,28 +41,12 @@ struct klp_ops {
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static DEFINE_MUTEX(klp_mutex);
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static LIST_HEAD(klp_patches);
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static LIST_HEAD(klp_ops);
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static struct kobject *klp_root_kobj;
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/* TODO: temporary stub */
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void klp_update_patch_state(struct task_struct *task) {}
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static struct klp_ops *klp_find_ops(unsigned long old_addr)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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list_for_each_entry(ops, &klp_ops, node) {
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func = list_first_entry(&ops->func_stack, struct klp_func,
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stack_node);
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if (func->old_addr == old_addr)
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return ops;
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}
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return NULL;
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}
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static bool klp_is_module(struct klp_object *obj)
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{
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return obj->name;
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@ -314,171 +279,6 @@ static int klp_write_object_relocations(struct module *pmod,
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return ret;
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}
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static void notrace klp_ftrace_handler(unsigned long ip,
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unsigned long parent_ip,
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struct ftrace_ops *fops,
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struct pt_regs *regs)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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ops = container_of(fops, struct klp_ops, fops);
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rcu_read_lock();
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func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
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stack_node);
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if (WARN_ON_ONCE(!func))
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goto unlock;
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klp_arch_set_pc(regs, (unsigned long)func->new_func);
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unlock:
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rcu_read_unlock();
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}
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/*
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* Convert a function address into the appropriate ftrace location.
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*
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* Usually this is just the address of the function, but on some architectures
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* it's more complicated so allow them to provide a custom behaviour.
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*/
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#ifndef klp_get_ftrace_location
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static unsigned long klp_get_ftrace_location(unsigned long faddr)
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{
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return faddr;
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}
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#endif
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static void klp_unpatch_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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if (WARN_ON(!func->patched))
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return;
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if (WARN_ON(!func->old_addr))
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return;
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ops = klp_find_ops(func->old_addr);
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if (WARN_ON(!ops))
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return;
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if (list_is_singular(&ops->func_stack)) {
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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (WARN_ON(!ftrace_loc))
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return;
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WARN_ON(unregister_ftrace_function(&ops->fops));
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WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0));
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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} else {
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list_del_rcu(&func->stack_node);
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}
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func->patched = false;
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}
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static int klp_patch_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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int ret;
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if (WARN_ON(!func->old_addr))
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return -EINVAL;
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if (WARN_ON(func->patched))
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return -EINVAL;
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ops = klp_find_ops(func->old_addr);
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if (!ops) {
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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (!ftrace_loc) {
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pr_err("failed to find location for function '%s'\n",
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func->old_name);
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return -EINVAL;
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}
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ops = kzalloc(sizeof(*ops), GFP_KERNEL);
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if (!ops)
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return -ENOMEM;
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ops->fops.func = klp_ftrace_handler;
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ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
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FTRACE_OPS_FL_DYNAMIC |
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FTRACE_OPS_FL_IPMODIFY;
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list_add(&ops->node, &klp_ops);
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INIT_LIST_HEAD(&ops->func_stack);
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list_add_rcu(&func->stack_node, &ops->func_stack);
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ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0);
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if (ret) {
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pr_err("failed to set ftrace filter for function '%s' (%d)\n",
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func->old_name, ret);
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goto err;
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}
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ret = register_ftrace_function(&ops->fops);
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if (ret) {
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pr_err("failed to register ftrace handler for function '%s' (%d)\n",
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func->old_name, ret);
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ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0);
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goto err;
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}
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} else {
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list_add_rcu(&func->stack_node, &ops->func_stack);
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}
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func->patched = true;
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return 0;
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err:
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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return ret;
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}
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static void klp_unpatch_object(struct klp_object *obj)
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{
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struct klp_func *func;
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klp_for_each_func(obj, func)
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if (func->patched)
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klp_unpatch_func(func);
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obj->patched = false;
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}
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static int klp_patch_object(struct klp_object *obj)
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{
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struct klp_func *func;
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int ret;
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if (WARN_ON(obj->patched))
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return -EINVAL;
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klp_for_each_func(obj, func) {
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ret = klp_patch_func(func);
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if (ret) {
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klp_unpatch_object(obj);
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return ret;
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}
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}
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obj->patched = true;
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return 0;
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}
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static int __klp_disable_patch(struct klp_patch *patch)
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{
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struct klp_object *obj;
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@ -0,0 +1,213 @@
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/*
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* patch.c - livepatch patching functions
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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* Copyright (C) 2014 SUSE
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* Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/livepatch.h>
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#include <linux/list.h>
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#include <linux/ftrace.h>
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#include <linux/rculist.h>
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#include <linux/slab.h>
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#include <linux/bug.h>
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#include <linux/printk.h>
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#include "patch.h"
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static LIST_HEAD(klp_ops);
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struct klp_ops *klp_find_ops(unsigned long old_addr)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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list_for_each_entry(ops, &klp_ops, node) {
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func = list_first_entry(&ops->func_stack, struct klp_func,
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stack_node);
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if (func->old_addr == old_addr)
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return ops;
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}
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return NULL;
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}
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static void notrace klp_ftrace_handler(unsigned long ip,
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unsigned long parent_ip,
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struct ftrace_ops *fops,
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struct pt_regs *regs)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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ops = container_of(fops, struct klp_ops, fops);
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rcu_read_lock();
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func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
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stack_node);
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if (WARN_ON_ONCE(!func))
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goto unlock;
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klp_arch_set_pc(regs, (unsigned long)func->new_func);
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unlock:
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rcu_read_unlock();
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}
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/*
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* Convert a function address into the appropriate ftrace location.
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*
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* Usually this is just the address of the function, but on some architectures
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* it's more complicated so allow them to provide a custom behaviour.
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*/
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#ifndef klp_get_ftrace_location
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static unsigned long klp_get_ftrace_location(unsigned long faddr)
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{
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return faddr;
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}
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#endif
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static void klp_unpatch_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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if (WARN_ON(!func->patched))
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return;
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if (WARN_ON(!func->old_addr))
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return;
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ops = klp_find_ops(func->old_addr);
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if (WARN_ON(!ops))
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return;
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if (list_is_singular(&ops->func_stack)) {
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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (WARN_ON(!ftrace_loc))
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return;
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WARN_ON(unregister_ftrace_function(&ops->fops));
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WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0));
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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} else {
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list_del_rcu(&func->stack_node);
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}
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func->patched = false;
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}
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static int klp_patch_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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int ret;
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if (WARN_ON(!func->old_addr))
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return -EINVAL;
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if (WARN_ON(func->patched))
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return -EINVAL;
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ops = klp_find_ops(func->old_addr);
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if (!ops) {
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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (!ftrace_loc) {
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pr_err("failed to find location for function '%s'\n",
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func->old_name);
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return -EINVAL;
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}
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ops = kzalloc(sizeof(*ops), GFP_KERNEL);
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if (!ops)
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return -ENOMEM;
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ops->fops.func = klp_ftrace_handler;
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ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
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FTRACE_OPS_FL_DYNAMIC |
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FTRACE_OPS_FL_IPMODIFY;
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list_add(&ops->node, &klp_ops);
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INIT_LIST_HEAD(&ops->func_stack);
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list_add_rcu(&func->stack_node, &ops->func_stack);
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ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0);
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if (ret) {
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pr_err("failed to set ftrace filter for function '%s' (%d)\n",
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func->old_name, ret);
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goto err;
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}
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ret = register_ftrace_function(&ops->fops);
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if (ret) {
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pr_err("failed to register ftrace handler for function '%s' (%d)\n",
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func->old_name, ret);
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ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0);
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goto err;
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}
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} else {
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list_add_rcu(&func->stack_node, &ops->func_stack);
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}
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func->patched = true;
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return 0;
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err:
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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return ret;
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}
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void klp_unpatch_object(struct klp_object *obj)
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{
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struct klp_func *func;
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klp_for_each_func(obj, func)
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if (func->patched)
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klp_unpatch_func(func);
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obj->patched = false;
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}
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int klp_patch_object(struct klp_object *obj)
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{
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struct klp_func *func;
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int ret;
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if (WARN_ON(obj->patched))
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return -EINVAL;
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klp_for_each_func(obj, func) {
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ret = klp_patch_func(func);
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if (ret) {
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klp_unpatch_object(obj);
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return ret;
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}
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}
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obj->patched = true;
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return 0;
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}
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@ -0,0 +1,32 @@
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#ifndef _LIVEPATCH_PATCH_H
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#define _LIVEPATCH_PATCH_H
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#include <linux/livepatch.h>
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#include <linux/list.h>
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#include <linux/ftrace.h>
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/**
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* struct klp_ops - structure for tracking registered ftrace ops structs
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*
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* A single ftrace_ops is shared between all enabled replacement functions
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* (klp_func structs) which have the same old_addr. This allows the switch
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* between function versions to happen instantaneously by updating the klp_ops
|
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* struct's func_stack list. The winner is the klp_func at the top of the
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* func_stack (front of the list).
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*
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* @node: node for the global klp_ops list
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* @func_stack: list head for the stack of klp_func's (active func is on top)
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* @fops: registered ftrace ops struct
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*/
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struct klp_ops {
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struct list_head node;
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struct list_head func_stack;
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struct ftrace_ops fops;
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};
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struct klp_ops *klp_find_ops(unsigned long old_addr);
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int klp_patch_object(struct klp_object *obj);
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void klp_unpatch_object(struct klp_object *obj);
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#endif /* _LIVEPATCH_PATCH_H */
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