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
10 static DEFINE_XARRAY(mte_pages);
11
mte_allocate_tag_storage(void)12 void *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
mte_free_tag_storage(char * storage)18 void mte_free_tag_storage(char *storage)
19 {
20 kfree(storage);
21 }
22
mte_save_tags(struct page * page)23 int 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, page_swap_entry(page).val, tag_storage,
38 GFP_KERNEL);
39 if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
40 mte_free_tag_storage(tag_storage);
41 return xa_err(ret);
42 } else if (ret) {
43 /* Entry is being replaced, free the old entry */
44 mte_free_tag_storage(ret);
45 }
46
47 return 0;
48 }
49
mte_restore_tags(swp_entry_t entry,struct page * page)50 void mte_restore_tags(swp_entry_t entry, struct page *page)
51 {
52 void *tags = xa_load(&mte_pages, 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
mte_invalidate_tags(int type,pgoff_t offset)63 void 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, entry.val);
67
68 mte_free_tag_storage(tags);
69 }
70
__mte_invalidate_tags(struct page * page)71 static inline void __mte_invalidate_tags(struct page *page)
72 {
73 swp_entry_t entry = page_swap_entry(page);
74
75 mte_invalidate_tags(swp_type(entry), swp_offset(entry));
76 }
77
mte_invalidate_tags_area(int type)78 void mte_invalidate_tags_area(int type)
79 {
80 swp_entry_t entry = swp_entry(type, 0);
81 swp_entry_t last_entry = swp_entry(type + 1, 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, xa_state.xa_index);
89 mte_free_tag_storage(tags);
90 }
91 xa_unlock(&mte_pages);
92 }
93
arch_prepare_to_swap(struct folio * folio)94 int 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
111 out:
112 while (i--)
113 __mte_invalidate_tags(folio_page(folio, i));
114 return err;
115 }
116
arch_swap_restore(swp_entry_t entry,struct folio * folio)117 void 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