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_area(int type)71 void mte_invalidate_tags_area(int type)
72 {
73 swp_entry_t entry = swp_entry(type, 0);
74 swp_entry_t last_entry = swp_entry(type + 1, 0);
75 void *tags;
76
77 XA_STATE(xa_state, &mte_pages, entry.val);
78
79 xa_lock(&mte_pages);
80 xas_for_each(&xa_state, tags, last_entry.val - 1) {
81 __xa_erase(&mte_pages, xa_state.xa_index);
82 mte_free_tag_storage(tags);
83 }
84 xa_unlock(&mte_pages);
85 }
86