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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/pagemap.h>
#include <linux/xarray.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <asm/mte.h>
static DEFINE_XARRAY(mte_pages);
void *mte_allocate_tag_storage(void)
{
/* tags granule is 16 bytes, 2 tags stored per byte */
return kmalloc(MTE_PAGE_TAG_STORAGE, GFP_KERNEL);
}
void mte_free_tag_storage(char *storage)
{
kfree(storage);
}
static int mte_save_tags(swp_entry_t entry, struct page *page)
{
void *tag_storage, *ret;
tag_storage = mte_allocate_tag_storage();
if (!tag_storage)
return -ENOMEM;
mte_save_page_tags(page_address(page), tag_storage);
ret = xa_store(&mte_pages, entry.val, tag_storage, GFP_KERNEL);
if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
mte_free_tag_storage(tag_storage);
return xa_err(ret);
} else if (ret) {
/* Entry is being replaced, free the old entry */
mte_free_tag_storage(ret);
}
return 0;
}
static void mte_restore_tags(swp_entry_t entry, struct page *page)
{
void *tags = xa_load(&mte_pages, entry.val);
if (!tags)
return;
if (try_page_mte_tagging(page)) {
mte_restore_page_tags(page_address(page), tags);
set_page_mte_tagged(page);
}
}
void mte_invalidate_tags(int type, pgoff_t offset)
{
swp_entry_t entry = swp_entry(type, offset);
void *tags = xa_erase(&mte_pages, entry.val);
mte_free_tag_storage(tags);
}
void mte_invalidate_tags_area(int type)
{
swp_entry_t entry = swp_entry(type, 0);
swp_entry_t last_entry = swp_entry(type + 1, 0);
void *tags;
XA_STATE(xa_state, &mte_pages, entry.val);
xa_lock(&mte_pages);
xas_for_each(&xa_state, tags, last_entry.val - 1) {
__xa_erase(&mte_pages, xa_state.xa_index);
mte_free_tag_storage(tags);
}
xa_unlock(&mte_pages);
}
int arch_prepare_to_swap(struct folio *folio)
{
long i, nr;
int err;
if (!system_supports_mte())
return 0;
nr = folio_nr_pages(folio);
for (i = 0; i < nr; i++) {
struct page *page = folio_page(folio, i);
if (!page_mte_tagged(page))
continue;
err = mte_save_tags(folio_swap_entry(folio, i), page);
if (err)
goto out;
}
return 0;
out:
while (i--) {
swp_entry_t swap = folio_swap_entry(folio, i);
mte_invalidate_tags(swp_type(swap), swp_offset(swap));
}
return err;
}
void arch_swap_restore(swp_entry_t entry, struct folio *folio)
{
long i, nr;
if (!system_supports_mte())
return;
nr = folio_nr_pages(folio);
for (i = 0; i < nr; i++) {
mte_restore_tags(entry, folio_page(folio, i));
entry.val++;
}
}
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