| 1 | |
| 2 | * livepatch.h - Kernel Live Patching Core
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| 3 | *
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| 4 | * Copyright (C) 2014 Seth Jennings <[email protected]>
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| 5 | * Copyright (C) 2014 SUSE
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| 6 | *
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| 7 | * This program is free software; you can redistribute it and/or
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| 8 | * modify it under the terms of the GNU General Public License
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| 9 | * as published by the Free Software Foundation; either version 2
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| 10 | * of the License, or (at your option) any later version.
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| 11 | *
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| 12 | * This program is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with this program; if not, see <http://www.gnu.org/licenses/>.
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| 19 |
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| 20 |
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| 21 | #ifndef _LINUX_LIVEPATCH_H_
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| 22 | #define _LINUX_LIVEPATCH_H_
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| 23 |
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| 24 | #include <linux/module.h>
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| 25 | #include <linux/ftrace.h>
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| 26 | #include <linux/completion.h>
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| 27 | #include <linux/list.h>
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| 28 |
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| 29 | #if IS_ENABLED(CONFIG_LIVEPATCH)
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| 30 |
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| 31 | #include <asm/livepatch.h>
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| 32 |
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| 33 |
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| 34 | #define KLP_UNDEFINED -1
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| 35 | #define KLP_UNPATCHED 0
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| 36 | #define KLP_PATCHED 1
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| 37 |
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| 38 | |
| 39 | * struct klp_func - function structure for live patching
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| 40 | * @old_name: name of the function to be patched
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| 41 | * @new_func: pointer to the patched function code
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| 42 | * @old_sympos: a hint indicating which symbol position the old function
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| 43 | * can be found (optional)
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| 44 | * @old_func: pointer to the function being patched
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| 45 | * @kobj: kobject for sysfs resources
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| 46 | * @node: list node for klp_object func_list
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| 47 | * @stack_node: list node for klp_ops func_stack list
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| 48 | * @old_size: size of the old function
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| 49 | * @new_size: size of the new function
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| 50 | * @kobj_added: @kobj has been added and needs freeing
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| 51 | * @nop: temporary patch to use the original code again; dyn. allocated
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| 52 | * @patched: the func has been added to the klp_ops list
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| 53 | * @transition: the func is currently being applied or reverted
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| 54 | *
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| 55 | * The patched and transition variables define the func's patching state. When
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| 56 | * patching, a func is always in one of the following states:
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| 57 | *
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| 58 | * patched=0 transition=0: unpatched
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| 59 | * patched=0 transition=1: unpatched, temporary starting state
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| 60 | * patched=1 transition=1: patched, may be visible to some tasks
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| 61 | * patched=1 transition=0: patched, visible to all tasks
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| 62 | *
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| 63 | * And when unpatching, it goes in the reverse order:
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| 64 | *
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| 65 | * patched=1 transition=0: patched, visible to all tasks
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| 66 | * patched=1 transition=1: patched, may be visible to some tasks
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| 67 | * patched=0 transition=1: unpatched, temporary ending state
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| 68 | * patched=0 transition=0: unpatched
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| 69 |
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| 70 | struct klp_func {
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| 71 |
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| 72 | const char *old_name;
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| 73 | void *new_func;
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| 74 | |
| 75 | * The old_sympos field is optional and can be used to resolve
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| 76 | * duplicate symbol names in livepatch objects. If this field is zero,
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| 77 | * it is expected the symbol is unique, otherwise patching fails. If
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| 78 | * this value is greater than zero then that occurrence of the symbol
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| 79 | * in kallsyms for the given object is used.
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| 80 |
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| 81 | unsigned long old_sympos;
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| 82 |
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| 83 |
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| 84 | void *old_func;
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| 85 | struct kobject kobj;
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| 86 | struct list_head node;
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| 87 | struct list_head stack_node;
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| 88 | unsigned long old_size, new_size;
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| 89 | bool kobj_added;
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| 90 | bool nop;
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| 91 | bool patched;
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| 92 | bool transition;
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| 93 | };
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| 94 |
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| 95 | struct klp_object;
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| 96 |
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| 97 | |
| 98 | * struct klp_callbacks - pre/post live-(un)patch callback structure
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| 99 | * @pre_patch: executed before code patching
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| 100 | * @post_patch: executed after code patching
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| 101 | * @pre_unpatch: executed before code unpatching
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| 102 | * @post_unpatch: executed after code unpatching
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| 103 | * @post_unpatch_enabled: flag indicating if post-unpatch callback
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| 104 | * should run
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| 105 | *
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| 106 | * All callbacks are optional. Only the pre-patch callback, if provided,
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| 107 | * will be unconditionally executed. If the parent klp_object fails to
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| 108 | * patch for any reason, including a non-zero error status returned from
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| 109 | * the pre-patch callback, no further callbacks will be executed.
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| 110 |
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| 111 | struct klp_callbacks {
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| 112 | int (*pre_patch)(struct klp_object *obj);
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| 113 | void (*post_patch)(struct klp_object *obj);
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| 114 | void (*pre_unpatch)(struct klp_object *obj);
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| 115 | void (*post_unpatch)(struct klp_object *obj);
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| 116 | bool post_unpatch_enabled;
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| 117 | };
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| 118 |
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| 119 | |
| 120 | * struct klp_object - kernel object structure for live patching
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| 121 | * @name: module name (or NULL for vmlinux)
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| 122 | * @funcs: function entries for functions to be patched in the object
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| 123 | * @callbacks: functions to be executed pre/post (un)patching
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| 124 | * @kobj: kobject for sysfs resources
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| 125 | * @func_list: dynamic list of the function entries
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| 126 | * @node: list node for klp_patch obj_list
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| 127 | * @mod: kernel module associated with the patched object
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| 128 | * (NULL for vmlinux)
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| 129 | * @kobj_added: @kobj has been added and needs freeing
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| 130 | * @dynamic: temporary object for nop functions; dynamically allocated
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| 131 | * @patched: the object's funcs have been added to the klp_ops list
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| 132 |
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| 133 | struct klp_object {
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| 134 |
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| 135 | const char *name;
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| 136 | struct klp_func *funcs;
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| 137 | struct klp_callbacks callbacks;
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| 138 |
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| 139 |
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| 140 | struct kobject kobj;
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| 141 | struct list_head func_list;
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| 142 | struct list_head node;
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| 143 | struct module *mod;
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| 144 | bool kobj_added;
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| 145 | bool dynamic;
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| 146 | bool patched;
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| 147 | };
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| 148 |
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| 149 | |
| 150 | * struct klp_patch - patch structure for live patching
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| 151 | * @mod: reference to the live patch module
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| 152 | * @objs: object entries for kernel objects to be patched
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| 153 | * @replace: replace all actively used patches
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| 154 | * @list: list node for global list of actively used patches
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| 155 | * @kobj: kobject for sysfs resources
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| 156 | * @obj_list: dynamic list of the object entries
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| 157 | * @kobj_added: @kobj has been added and needs freeing
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| 158 | * @enabled: the patch is enabled (but operation may be incomplete)
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| 159 | * @forced: was involved in a forced transition
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| 160 | * @free_work: patch cleanup from workqueue-context
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| 161 | * @finish: for waiting till it is safe to remove the patch module
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| 162 |
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| 163 | struct klp_patch {
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| 164 |
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| 165 | struct module *mod;
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| 166 | struct klp_object *objs;
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| 167 | bool replace;
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| 168 |
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| 169 |
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| 170 | struct list_head list;
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| 171 | struct kobject kobj;
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| 172 | struct list_head obj_list;
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| 173 | bool kobj_added;
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| 174 | bool enabled;
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| 175 | bool forced;
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| 176 | struct work_struct free_work;
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| 177 | struct completion finish;
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| 178 | };
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| 179 |
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| 180 | #define klp_for_each_object_static(patch, obj) \
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| 181 | for (obj = patch->objs; obj->funcs || obj->name; obj++)
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| 182 |
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| 183 | #define klp_for_each_object_safe(patch, obj, tmp_obj) \
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| 184 | list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
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| 185 |
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| 186 | #define klp_for_each_object(patch, obj) \
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| 187 | list_for_each_entry(obj, &patch->obj_list, node)
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| 188 |
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| 189 | #define klp_for_each_func_static(obj, func) \
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| 190 | for (func = obj->funcs; \
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| 191 | func->old_name || func->new_func || func->old_sympos; \
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| 192 | func++)
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| 193 |
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| 194 | #define klp_for_each_func_safe(obj, func, tmp_func) \
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| 195 | list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
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| 196 |
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| 197 | #define klp_for_each_func(obj, func) \
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| 198 | list_for_each_entry(func, &obj->func_list, node)
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| 199 |
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| 200 | int klp_enable_patch(struct klp_patch *);
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| 201 |
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| 202 | void arch_klp_init_object_loaded(struct klp_patch *patch,
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| 203 | struct klp_object *obj);
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| 204 |
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| 205 |
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| 206 | int klp_module_coming(struct module *mod);
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| 207 | void klp_module_going(struct module *mod);
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| 208 |
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| 209 | void klp_copy_process(struct task_struct *child);
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| 210 | void klp_update_patch_state(struct task_struct *task);
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| 211 |
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| 212 | static inline bool klp_patch_pending(struct task_struct *task)
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| 213 | {
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| 214 | return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
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| 215 | }
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| 216 |
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| 217 | static inline bool klp_have_reliable_stack(void)
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| 218 | {
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| 219 | return IS_ENABLED(CONFIG_STACKTRACE) &&
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| 220 | IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
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| 221 | }
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| 222 |
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| 223 | typedef int (*klp_shadow_ctor_t)(void *obj,
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| 224 | void *shadow_data,
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| 225 | void *ctor_data);
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| 226 | typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data);
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| 227 |
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| 228 | void *klp_shadow_get(void *obj, unsigned long id);
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| 229 | void *klp_shadow_alloc(void *obj, unsigned long id,
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| 230 | size_t size, gfp_t gfp_flags,
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| 231 | klp_shadow_ctor_t ctor, void *ctor_data);
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| 232 | void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
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| 233 | size_t size, gfp_t gfp_flags,
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| 234 | klp_shadow_ctor_t ctor, void *ctor_data);
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| 235 | void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
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| 236 | void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
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| 237 |
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| 238 | #else
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| 239 |
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| 240 | static inline int klp_module_coming(struct module *mod) { return 0; }
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| 241 | static inline void klp_module_going(struct module *mod) {}
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| 242 | static inline bool klp_patch_pending(struct task_struct *task) { return false; }
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| 243 | static inline void klp_update_patch_state(struct task_struct *task) {}
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| 244 | static inline void klp_copy_process(struct task_struct *child) {}
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| 245 |
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| 246 | #endif
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| 247 |
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| 248 | #endif
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