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arm64: mte: Ensure the cleared tags are visible before setting the PTE

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As an optimisation, only pages mapped with PROT_MTE in user space have
the MTE tags zeroed. This is done lazily at the set_pte_at() time via
mte_sync_tags(). However, this function is missing a barrier and another
CPU may see the PTE updated before the zeroed tags are visible. Add an
smp_wmb() barrier if the mapping is Normal Tagged.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: 34bfeea4a9e9 ("arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE")
Cc: <stable@vger.kernel.org> # 5.10.x
Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Steven Price <steven.price@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Link: https://lore.kernel.org/r/20220517093532.127095-1-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Catalin Marinas 2022-05-17 10:35:32 +01:00 committed by Will Deacon
parent eb3d8ea3e1
commit 1d0cb4c886
1 changed files with 3 additions and 0 deletions
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3
arch/arm64/kernel/mte.c
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@ -76,6 +76,9 @@ void mte_sync_tags(pte_t old_pte, pte_t pte)
mte_sync_page_tags(page, old_pte, check_swap,
pte_is_tagged);
}
/* ensure the tags are visible before the PTE is set */
smp_wmb();
}
int memcmp_pages(struct page *page1, struct page *page2)