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| author | Steven Price <steven.price@arm.com> | 2021-06-21 14:17:11 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2021-06-22 11:38:50 +0300 |
| commit | 69e3b846d8a753f9f279f29531ca56b0f7563ad0 (patch) | |
| tree | 7d68951ac80b0e06327e833df40cbe2376b5a31b /arch/arm64/kernel/mte.c | |
| parent | 8124c8a6b35386f73523d27eacb71b5364a68c4c (diff) | |
| download | linux-69e3b846d8a753f9f279f29531ca56b0f7563ad0.tar.xz | |
arm64: mte: Sync tags for pages where PTE is untagged
A KVM guest could store tags in a page even if the VMM hasn't mapped
the page with PROT_MTE. So when restoring pages from swap we will
need to check to see if there are any saved tags even if !pte_tagged().
However don't check pages for which pte_access_permitted() returns false
as these will not have been swapped out.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210621111716.37157-2-steven.price@arm.com
Diffstat (limited to 'arch/arm64/kernel/mte.c')
| -rw-r--r-- | arch/arm64/kernel/mte.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 125a10e413e9..69b3fde8759e 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -32,10 +32,9 @@ DEFINE_STATIC_KEY_FALSE(mte_async_mode); EXPORT_SYMBOL_GPL(mte_async_mode); #endif -static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) +static void mte_sync_page_tags(struct page *page, pte_t old_pte, + bool check_swap, bool pte_is_tagged) { - pte_t old_pte = READ_ONCE(*ptep); - if (check_swap && is_swap_pte(old_pte)) { swp_entry_t entry = pte_to_swp_entry(old_pte); @@ -43,6 +42,9 @@ static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) return; } + if (!pte_is_tagged) + return; + page_kasan_tag_reset(page); /* * We need smp_wmb() in between setting the flags and clearing the @@ -55,16 +57,22 @@ static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) mte_clear_page_tags(page_address(page)); } -void mte_sync_tags(pte_t *ptep, pte_t pte) +void mte_sync_tags(pte_t old_pte, pte_t pte) { struct page *page = pte_page(pte); long i, nr_pages = compound_nr(page); bool check_swap = nr_pages == 1; + bool pte_is_tagged = pte_tagged(pte); + + /* Early out if there's nothing to do */ + if (!check_swap && !pte_is_tagged) + return; /* if PG_mte_tagged is set, tags have already been initialised */ for (i = 0; i < nr_pages; i++, page++) { if (!test_and_set_bit(PG_mte_tagged, &page->flags)) - mte_sync_page_tags(page, ptep, check_swap); + mte_sync_page_tags(page, old_pte, check_swap, + pte_is_tagged); } } |