summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorCatalin Marinas <catalin.marinas@arm.com>2022-05-17 12:35:32 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-25 10:17:56 +0300
commit6013ef5f51e0861a904b74a694e621bb451fe7ae (patch)
tree08588ab7d371cba98b2636a3796d4f129439262c
parenta817f78ed69bba10d724587dab84a164dac05900 (diff)
downloadlinux-6013ef5f51e0861a904b74a694e621bb451fe7ae.tar.xz
arm64: mte: Ensure the cleared tags are visible before setting the PTE
commit 1d0cb4c8864addc362bae98e8ffa5500c87e1227 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arm64/kernel/mte.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 7a66a7d9c1ff..4a069f85bd91 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -45,6 +45,9 @@ void mte_sync_tags(pte_t *ptep, pte_t pte)
if (!test_and_set_bit(PG_mte_tagged, &page->flags))
mte_sync_page_tags(page, ptep, check_swap);
}
+
+ /* ensure the tags are visible before the PTE is set */
+ smp_wmb();
}
int memcmp_pages(struct page *page1, struct page *page2)