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| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
|---|---|
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 2025, Google LLC. |
| 5 | * Pasha Tatashin <pasha.tatashin@soleen.com> |
| 6 | */ |
| 7 | #ifndef _LINUX_LIVEUPDATE_H |
| 8 | #define _LINUX_LIVEUPDATE_H |
| 9 | |
| 10 | #include <linux/bug.h> |
| 11 | #include <linux/compiler.h> |
| 12 | #include <linux/kho/abi/luo.h> |
| 13 | #include <linux/list.h> |
| 14 | #include <linux/types.h> |
| 15 | #include <uapi/linux/liveupdate.h> |
| 16 | |
| 17 | struct liveupdate_file_handler; |
| 18 | struct file; |
| 19 | |
| 20 | /** |
| 21 | * struct liveupdate_file_op_args - Arguments for file operation callbacks. |
| 22 | * @handler: The file handler being called. |
| 23 | * @retrieved: The retrieve status for the 'can_finish / finish' |
| 24 | * operation. |
| 25 | * @file: The file object. For retrieve: [OUT] The callback sets |
| 26 | * this to the new file. For other ops: [IN] The caller sets |
| 27 | * this to the file being operated on. |
| 28 | * @serialized_data: The opaque u64 handle, preserve/prepare/freeze may update |
| 29 | * this field. |
| 30 | * @private_data: Private data for the file used to hold runtime state that |
| 31 | * is not preserved. Set by the handler's .preserve() |
| 32 | * callback, and must be freed in the handler's |
| 33 | * .unpreserve() callback. |
| 34 | * |
| 35 | * This structure bundles all parameters for the file operation callbacks. |
| 36 | * The 'data' and 'file' fields are used for both input and output. |
| 37 | */ |
| 38 | struct liveupdate_file_op_args { |
| 39 | struct liveupdate_file_handler *handler; |
| 40 | bool retrieved; |
| 41 | struct file *file; |
| 42 | u64 serialized_data; |
| 43 | void *private_data; |
| 44 | }; |
| 45 | |
| 46 | /** |
| 47 | * struct liveupdate_file_ops - Callbacks for live-updatable files. |
| 48 | * @can_preserve: Required. Lightweight check to see if this handler is |
| 49 | * compatible with the given file. |
| 50 | * @preserve: Required. Performs state-saving for the file. |
| 51 | * @unpreserve: Required. Cleans up any resources allocated by @preserve. |
| 52 | * @freeze: Optional. Final actions just before kernel transition. |
| 53 | * @unfreeze: Optional. Undo freeze operations. |
| 54 | * @retrieve: Required. Restores the file in the new kernel. |
| 55 | * @can_finish: Optional. Check if this FD can finish, i.e. all restoration |
| 56 | * pre-requirements for this FD are satisfied. Called prior to |
| 57 | * finish, in order to do successful finish calls for all |
| 58 | * resources in the session. |
| 59 | * @finish: Required. Final cleanup in the new kernel. |
| 60 | * @owner: Module reference |
| 61 | * |
| 62 | * All operations (except can_preserve) receive a pointer to a |
| 63 | * 'struct liveupdate_file_op_args' containing the necessary context. |
| 64 | */ |
| 65 | struct liveupdate_file_ops { |
| 66 | bool (*can_preserve)(struct liveupdate_file_handler *handler, |
| 67 | struct file *file); |
| 68 | int (*preserve)(struct liveupdate_file_op_args *args); |
| 69 | void (*unpreserve)(struct liveupdate_file_op_args *args); |
| 70 | int (*freeze)(struct liveupdate_file_op_args *args); |
| 71 | void (*unfreeze)(struct liveupdate_file_op_args *args); |
| 72 | int (*retrieve)(struct liveupdate_file_op_args *args); |
| 73 | bool (*can_finish)(struct liveupdate_file_op_args *args); |
| 74 | void (*finish)(struct liveupdate_file_op_args *args); |
| 75 | struct module *owner; |
| 76 | }; |
| 77 | |
| 78 | /** |
| 79 | * struct liveupdate_file_handler - Represents a handler for a live-updatable file type. |
| 80 | * @ops: Callback functions |
| 81 | * @compatible: The compatibility string (e.g., "memfd-v1", "vfiofd-v1") |
| 82 | * that uniquely identifies the file type this handler |
| 83 | * supports. This is matched against the compatible string |
| 84 | * associated with individual &struct file instances. |
| 85 | * |
| 86 | * Modules that want to support live update for specific file types should |
| 87 | * register an instance of this structure. LUO uses this registration to |
| 88 | * determine if a given file can be preserved and to find the appropriate |
| 89 | * operations to manage its state across the update. |
| 90 | */ |
| 91 | struct liveupdate_file_handler { |
| 92 | const struct liveupdate_file_ops *ops; |
| 93 | const char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH]; |
| 94 | |
| 95 | /* private: */ |
| 96 | |
| 97 | /* |
| 98 | * Used for linking this handler instance into a global list of |
| 99 | * registered file handlers. |
| 100 | */ |
| 101 | struct list_head __private list; |
| 102 | }; |
| 103 | |
| 104 | #ifdef CONFIG_LIVEUPDATE |
| 105 | |
| 106 | /* Return true if live update orchestrator is enabled */ |
| 107 | bool liveupdate_enabled(void); |
| 108 | |
| 109 | /* Called during kexec to tell LUO that entered into reboot */ |
| 110 | int liveupdate_reboot(void); |
| 111 | |
| 112 | int liveupdate_register_file_handler(struct liveupdate_file_handler *fh); |
| 113 | int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh); |
| 114 | |
| 115 | #else /* CONFIG_LIVEUPDATE */ |
| 116 | |
| 117 | static inline bool liveupdate_enabled(void) |
| 118 | { |
| 119 | return false; |
| 120 | } |
| 121 | |
| 122 | static inline int liveupdate_reboot(void) |
| 123 | { |
| 124 | return 0; |
| 125 | } |
| 126 | |
| 127 | static inline int liveupdate_register_file_handler(struct liveupdate_file_handler *fh) |
| 128 | { |
| 129 | return -EOPNOTSUPP; |
| 130 | } |
| 131 | |
| 132 | static inline int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh) |
| 133 | { |
| 134 | return -EOPNOTSUPP; |
| 135 | } |
| 136 | |
| 137 | #endif /* CONFIG_LIVEUPDATE */ |
| 138 | #endif /* _LINUX_LIVEUPDATE_H */ |
| 139 |
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