Messages in this thread | | | Date | Wed, 23 Jun 2021 12:28:21 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v1] arm64: tlb: fix the TTL value of tlb_get_level |
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On Wed, Jun 23, 2021 at 12:04:12PM +0100, Will Deacon wrote: > On Wed, Jun 23, 2021 at 03:05:22PM +0800, Zhenyu Ye wrote: > > The TTL field indicates the level of page table walk holding the *leaf* > > entry for the address being invalidated. But currently, the TTL field > > may be set to an incorrent value in the following stack: > > > > pte_free_tlb > > __pte_free_tlb > > tlb_remove_table > > tlb_table_invalidate > > tlb_flush_mmu_tlbonly > > tlb_flush > > > > In this case, we just want to flush a PTE page, but the tlb->cleared_pmds > > is set and we get tlb_level = 2 in the tlb_get_level() function. This may > > cause some unexpected problems. > > > > This patch set the TTL field to 0 if tlb->freed_tables is set. The > > tlb->freed_tables indicates page table pages are freed, not the leaf > > entry. > > > > Fixes: c4ab2cbc1d87 ("arm64: tlb: Set the TTL field in flush_tlb_range") > > Reported-by: ZhuRui <zhurui3@huawei.com> > > Signed-off-by: Zhenyu Ye <yezhenyu2@huawei.com> > > --- > > arch/arm64/include/asm/tlb.h | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h > > index 61c97d3b58c7..c995d1f4594f 100644 > > --- a/arch/arm64/include/asm/tlb.h > > +++ b/arch/arm64/include/asm/tlb.h > > @@ -28,6 +28,10 @@ static void tlb_flush(struct mmu_gather *tlb); > > */ > > static inline int tlb_get_level(struct mmu_gather *tlb) > > { > > + /* The TTL field is only valid for the leaf entry. */ > > + if (tlb->freed_tables) > > + return 0; > > + > > if (tlb->cleared_ptes && !(tlb->cleared_pmds || > > tlb->cleared_puds || > > tlb->cleared_p4ds)) > > Thanks. I can't see a better way around this, so I'll queue the patch.
If you haven't queued it already, feel free to add:
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
I'd also add:
Cc: <stable@vger.kernel.org> # 5.9.x
-- Catalin
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