289 lines
11 KiB
C
289 lines
11 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2025, Google LLC.
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* Pasha Tatashin <pasha.tatashin@soleen.com>
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*/
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#ifndef _LINUX_LIVEUPDATE_H
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#define _LINUX_LIVEUPDATE_H
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#include <linux/bug.h>
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#include <linux/compiler.h>
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#include <linux/kho/abi/luo.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <uapi/linux/liveupdate.h>
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struct liveupdate_file_handler;
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struct liveupdate_flb;
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struct liveupdate_session;
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struct file;
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/**
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* struct liveupdate_file_op_args - Arguments for file operation callbacks.
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* @handler: The file handler being called.
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* @retrieve_status: The retrieve status for the 'can_finish / finish'
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* operation. A value of 0 means the retrieve has not been
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* attempted, a positive value means the retrieve was
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* successful, and a negative value means the retrieve failed,
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* and the value is the error code of the call.
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* @file: The file object. For retrieve: [OUT] The callback sets
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* this to the new file. For other ops: [IN] The caller sets
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* this to the file being operated on.
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* @serialized_data: The opaque u64 handle, preserve/prepare/freeze may update
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* this field.
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* @private_data: Private data for the file used to hold runtime state that
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* is not preserved. Set by the handler's .preserve()
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* callback, and must be freed in the handler's
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* .unpreserve() callback.
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*
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* This structure bundles all parameters for the file operation callbacks.
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* The 'data' and 'file' fields are used for both input and output.
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*/
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struct liveupdate_file_op_args {
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struct liveupdate_file_handler *handler;
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int retrieve_status;
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struct file *file;
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u64 serialized_data;
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void *private_data;
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};
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/**
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* struct liveupdate_file_ops - Callbacks for live-updatable files.
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* @can_preserve: Required. Lightweight check to see if this handler is
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* compatible with the given file.
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* @preserve: Required. Performs state-saving for the file.
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* @unpreserve: Required. Cleans up any resources allocated by @preserve.
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* @freeze: Optional. Final actions just before kernel transition.
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* @unfreeze: Optional. Undo freeze operations.
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* @retrieve: Required. Restores the file in the new kernel.
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* @can_finish: Optional. Check if this FD can finish, i.e. all restoration
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* pre-requirements for this FD are satisfied. Called prior to
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* finish, in order to do successful finish calls for all
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* resources in the session.
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* @finish: Required. Final cleanup in the new kernel.
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* @owner: Module reference
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*
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* All operations (except can_preserve) receive a pointer to a
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* 'struct liveupdate_file_op_args' containing the necessary context.
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*/
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struct liveupdate_file_ops {
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bool (*can_preserve)(struct liveupdate_file_handler *handler,
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struct file *file);
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int (*preserve)(struct liveupdate_file_op_args *args);
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void (*unpreserve)(struct liveupdate_file_op_args *args);
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int (*freeze)(struct liveupdate_file_op_args *args);
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void (*unfreeze)(struct liveupdate_file_op_args *args);
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int (*retrieve)(struct liveupdate_file_op_args *args);
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bool (*can_finish)(struct liveupdate_file_op_args *args);
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void (*finish)(struct liveupdate_file_op_args *args);
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struct module *owner;
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};
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/**
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* struct liveupdate_file_handler - Represents a handler for a live-updatable file type.
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* @ops: Callback functions
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* @compatible: The compatibility string (e.g., "memfd-v1", "vfiofd-v1")
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* that uniquely identifies the file type this handler
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* supports. This is matched against the compatible string
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* associated with individual &struct file instances.
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*
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* Modules that want to support live update for specific file types should
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* register an instance of this structure. LUO uses this registration to
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* determine if a given file can be preserved and to find the appropriate
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* operations to manage its state across the update.
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*/
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struct liveupdate_file_handler {
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const struct liveupdate_file_ops *ops;
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const char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH];
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/* private: */
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/*
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* Used for linking this handler instance into a global list of
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* registered file handlers.
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*/
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struct list_head __private list;
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/* A list of FLB dependencies. */
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struct list_head __private flb_list;
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};
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/**
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* struct liveupdate_flb_op_args - Arguments for FLB operation callbacks.
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* @flb: The global FLB instance for which this call is performed.
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* @data: For .preserve(): [OUT] The callback sets this field.
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* For .unpreserve(): [IN] The handle from .preserve().
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* For .retrieve(): [IN] The handle from .preserve().
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* @obj: For .preserve(): [OUT] Sets this to the live object.
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* For .retrieve(): [OUT] Sets this to the live object.
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* For .finish(): [IN] The live object from .retrieve().
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*
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* This structure bundles all parameters for the FLB operation callbacks.
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*/
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struct liveupdate_flb_op_args {
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struct liveupdate_flb *flb;
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u64 data;
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void *obj;
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};
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/**
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* struct liveupdate_flb_ops - Callbacks for global File-Lifecycle-Bound data.
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* @preserve: Called when the first file using this FLB is preserved.
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* The callback must save its state and return a single,
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* self-contained u64 handle by setting the 'argp->data'
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* field and 'argp->obj'.
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* @unpreserve: Called when the last file using this FLB is unpreserved
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* (aborted before reboot). Receives the handle via
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* 'argp->data' and live object via 'argp->obj'.
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* @retrieve: Called on-demand in the new kernel, the first time a
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* component requests access to the shared object. It receives
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* the preserved handle via 'argp->data' and must reconstruct
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* the live object, returning it by setting the 'argp->obj'
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* field.
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* @finish: Called in the new kernel when the last file using this FLB
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* is finished. Receives the live object via 'argp->obj' for
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* cleanup.
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* @owner: Module reference
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*
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* Operations that manage global shared data with file bound lifecycle,
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* triggered by the first file that uses it and concluded by the last file that
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* uses it, across all sessions.
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*/
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struct liveupdate_flb_ops {
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int (*preserve)(struct liveupdate_flb_op_args *argp);
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void (*unpreserve)(struct liveupdate_flb_op_args *argp);
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int (*retrieve)(struct liveupdate_flb_op_args *argp);
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void (*finish)(struct liveupdate_flb_op_args *argp);
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struct module *owner;
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};
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/*
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* struct luo_flb_private_state - Private FLB state structures.
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* @count: The number of preserved files currently depending on this FLB.
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* This is used to trigger the preserve/unpreserve/finish ops on the
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* first/last file.
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* @data: The opaque u64 handle returned by .preserve() or passed to
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* .retrieve().
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* @obj: The live kernel object returned by .preserve() or .retrieve().
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* @lock: A mutex that protects all fields within this structure, providing
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* the synchronization service for the FLB's ops.
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* @finished: True once the FLB's finish() callback has run.
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* @retrieved: True once the FLB's retrieve() callback has run.
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*/
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struct luo_flb_private_state {
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long count;
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u64 data;
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void *obj;
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struct mutex lock;
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bool finished;
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bool retrieved;
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};
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/*
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* struct luo_flb_private - Keep separate incoming and outgoing states.
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* @list: A global list of registered FLBs.
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* @outgoing: The runtime state for the pre-reboot
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* (preserve/unpreserve) lifecycle.
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* @incoming: The runtime state for the post-reboot (retrieve/finish)
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* lifecycle.
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* @users: With how many File-Handlers this FLB is registered.
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* @initialized: true when private fields have been initialized.
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*/
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struct luo_flb_private {
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struct list_head list;
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struct luo_flb_private_state outgoing;
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struct luo_flb_private_state incoming;
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int users;
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bool initialized;
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};
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/**
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* struct liveupdate_flb - A global definition for a shared data object.
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* @ops: Callback functions
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* @compatible: The compatibility string (e.g., "iommu-core-v1"
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* that uniquely identifies the FLB type this handler
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* supports. This is matched against the compatible string
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* associated with individual &struct liveupdate_flb
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* instances.
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*
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* This struct is the "template" that a driver registers to define a shared,
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* file-lifecycle-bound object. The actual runtime state (the live object,
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* refcount, etc.) is managed privately by the LUO core.
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*/
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struct liveupdate_flb {
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const struct liveupdate_flb_ops *ops;
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const char compatible[LIVEUPDATE_FLB_COMPAT_LENGTH];
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/* private: */
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struct luo_flb_private __private private;
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};
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#ifdef CONFIG_LIVEUPDATE
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/* Return true if live update orchestrator is enabled */
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bool liveupdate_enabled(void);
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/* Called during kexec to tell LUO that entered into reboot */
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int liveupdate_reboot(void);
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int liveupdate_register_file_handler(struct liveupdate_file_handler *fh);
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int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh);
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int liveupdate_register_flb(struct liveupdate_file_handler *fh,
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struct liveupdate_flb *flb);
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int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
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struct liveupdate_flb *flb);
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int liveupdate_flb_get_incoming(struct liveupdate_flb *flb, void **objp);
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int liveupdate_flb_get_outgoing(struct liveupdate_flb *flb, void **objp);
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#else /* CONFIG_LIVEUPDATE */
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static inline bool liveupdate_enabled(void)
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{
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return false;
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}
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static inline int liveupdate_reboot(void)
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{
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return 0;
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}
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static inline int liveupdate_register_file_handler(struct liveupdate_file_handler *fh)
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{
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return -EOPNOTSUPP;
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}
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static inline int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
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{
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return -EOPNOTSUPP;
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}
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static inline int liveupdate_register_flb(struct liveupdate_file_handler *fh,
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struct liveupdate_flb *flb)
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{
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return -EOPNOTSUPP;
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}
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static inline int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
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struct liveupdate_flb *flb)
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{
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return -EOPNOTSUPP;
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}
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static inline int liveupdate_flb_get_incoming(struct liveupdate_flb *flb,
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void **objp)
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{
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return -EOPNOTSUPP;
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}
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static inline int liveupdate_flb_get_outgoing(struct liveupdate_flb *flb,
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void **objp)
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{
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return -EOPNOTSUPP;
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}
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#endif /* CONFIG_LIVEUPDATE */
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#endif /* _LINUX_LIVEUPDATE_H */
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