Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2
3#ifndef _LINUX_KHO_RADIX_TREE_H
4#define _LINUX_KHO_RADIX_TREE_H
5
6#include <linux/err.h>
7#include <linux/errno.h>
8#include <linux/mutex_types.h>
9#include <linux/types.h>
10
11/**
12 * DOC: Kexec Handover Radix Tree
13 *
14 * This is a radix tree implementation for tracking physical memory pages
15 * across kexec transitions. It was developed for the KHO mechanism but is
16 * designed for broader use by any subsystem that needs to preserve pages.
17 *
18 * The radix tree is a multi-level tree where leaf nodes are bitmaps
19 * representing individual pages. To allow pages of different sizes (orders)
20 * to be stored efficiently in a single tree, it uses a unique key encoding
21 * scheme. Each key is an unsigned long that combines a page's physical
22 * address and its order.
23 *
24 * Client code is responsible for allocating the root node of the tree,
25 * initializing the mutex lock, and managing its lifecycle. It must use the
26 * tree data structures defined in the KHO ABI,
27 * `include/linux/kho/abi/kexec_handover.h`.
28 */
29
30struct kho_radix_node;
31
32struct kho_radix_tree {
33 struct kho_radix_node *root;
34 struct mutex lock; /* protects the tree's structure and root pointer */
35};
36
37typedef int (*kho_radix_tree_walk_callback_t)(phys_addr_t phys,
38 unsigned int order);
39
40#ifdef CONFIG_KEXEC_HANDOVER
41
42int kho_radix_add_page(struct kho_radix_tree *tree, unsigned long pfn,
43 unsigned int order);
44
45void kho_radix_del_page(struct kho_radix_tree *tree, unsigned long pfn,
46 unsigned int order);
47
48int kho_radix_walk_tree(struct kho_radix_tree *tree,
49 kho_radix_tree_walk_callback_t cb);
50
51#else /* #ifdef CONFIG_KEXEC_HANDOVER */
52
53static inline int kho_radix_add_page(struct kho_radix_tree *tree, long pfn,
54 unsigned int order)
55{
56 return -EOPNOTSUPP;
57}
58
59static inline void kho_radix_del_page(struct kho_radix_tree *tree,
60 unsigned long pfn, unsigned int order) { }
61
62static inline int kho_radix_walk_tree(struct kho_radix_tree *tree,
63 kho_radix_tree_walk_callback_t cb)
64{
65 return -EOPNOTSUPP;
66}
67
68#endif /* #ifdef CONFIG_KEXEC_HANDOVER */
69
70#endif /* _LINUX_KHO_RADIX_TREE_H */