1// SPDX-License-Identifier: GPL-2.0-only
2
3#include <linux/pagemap.h>
4#include <linux/xarray.h>
5#include <linux/slab.h>
6#include <linux/swap.h>
7#include <linux/swapops.h>
8#include <asm/mte.h>
9
10static DEFINE_XARRAY(mte_pages);
11
12void *mte_allocate_tag_storage(void)
13{
14 /* tags granule is 16 bytes, 2 tags stored per byte */
15 return kmalloc(MTE_PAGE_TAG_STORAGE, GFP_KERNEL);
16}
17
18void mte_free_tag_storage(char *storage)
19{
20 kfree(objp: storage);
21}
22
23int mte_save_tags(struct page *page)
24{
25 void *tag_storage, *ret;
26
27 if (!page_mte_tagged(page))
28 return 0;
29
30 tag_storage = mte_allocate_tag_storage();
31 if (!tag_storage)
32 return -ENOMEM;
33
34 mte_save_page_tags(page_address(page), tag_storage);
35
36 /* lookup the swap entry.val from the page */
37 ret = xa_store(&mte_pages, index: page_swap_entry(page).val, entry: tag_storage,
38 GFP_KERNEL);
39 if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
40 mte_free_tag_storage(storage: tag_storage);
41 return xa_err(entry: ret);
42 } else if (ret) {
43 /* Entry is being replaced, free the old entry */
44 mte_free_tag_storage(storage: ret);
45 }
46
47 return 0;
48}
49
50void mte_restore_tags(swp_entry_t entry, struct page *page)
51{
52 void *tags = xa_load(&mte_pages, index: entry.val);
53
54 if (!tags)
55 return;
56
57 if (try_page_mte_tagging(page)) {
58 mte_restore_page_tags(page_address(page), tags);
59 set_page_mte_tagged(page);
60 }
61}
62
63void mte_invalidate_tags(int type, pgoff_t offset)
64{
65 swp_entry_t entry = swp_entry(type, offset);
66 void *tags = xa_erase(&mte_pages, index: entry.val);
67
68 mte_free_tag_storage(storage: tags);
69}
70
71static inline void __mte_invalidate_tags(struct page *page)
72{
73 swp_entry_t entry = page_swap_entry(page);
74
75 mte_invalidate_tags(type: swp_type(entry), offset: swp_offset(entry));
76}
77
78void mte_invalidate_tags_area(int type)
79{
80 swp_entry_t entry = swp_entry(type, offset: 0);
81 swp_entry_t last_entry = swp_entry(type: type + 1, offset: 0);
82 void *tags;
83
84 XA_STATE(xa_state, &mte_pages, entry.val);
85
86 xa_lock(&mte_pages);
87 xas_for_each(&xa_state, tags, last_entry.val - 1) {
88 __xa_erase(&mte_pages, index: xa_state.xa_index);
89 mte_free_tag_storage(storage: tags);
90 }
91 xa_unlock(&mte_pages);
92}
93
94int arch_prepare_to_swap(struct folio *folio)
95{
96 long i, nr;
97 int err;
98
99 if (!system_supports_mte())
100 return 0;
101
102 nr = folio_nr_pages(folio);
103
104 for (i = 0; i < nr; i++) {
105 err = mte_save_tags(folio_page(folio, i));
106 if (err)
107 goto out;
108 }
109 return 0;
110
111out:
112 while (i--)
113 __mte_invalidate_tags(folio_page(folio, i));
114 return err;
115}
116
117void arch_swap_restore(swp_entry_t entry, struct folio *folio)
118{
119 long i, nr;
120
121 if (!system_supports_mte())
122 return;
123
124 nr = folio_nr_pages(folio);
125
126 for (i = 0; i < nr; i++) {
127 mte_restore_tags(entry, folio_page(folio, i));
128 entry.val++;
129 }
130}
131

source code of linux/arch/arm64/mm/mteswap.c