Messages in this thread | | | From | Guo Ren <> | Date | Mon, 21 Nov 2022 18:03:28 +0800 | Subject | Re: [PATCH] LoongArch: Set _PAGE_DIRTY only if _PAGE_MODIFIED is set in {pmd,pte}_mkwrite() |
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On Mon, Nov 21, 2022 at 2:51 PM Huacai Chen <chenhuacai@loongson.cn> wrote: > > Set _PAGE_DIRTY only if _PAGE_MODIFIED is set in {pmd,pte}_mkwrite(). > Otherwise, _PAGE_DIRTY silences the TLB modify exception and make us > have no chance to mark a pmd/pte dirty (_PAGE_MODIFIED) for software. Yes, the "VALID/DIRTY" is a bad hardware pgtable-bit design. It caused the software to waste more bits in PTE. We need hardware P/R/W/A/D definitions. It seems from MIPS in history, C-SKY also follows that :P.
Reviewed-by: Guo Ren <guoren@kernel.org>
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> > --- > arch/loongarch/include/asm/pgtable.h | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h > index debbe116f105..aa0e0e0d4ee5 100644 > --- a/arch/loongarch/include/asm/pgtable.h > +++ b/arch/loongarch/include/asm/pgtable.h > @@ -357,7 +357,9 @@ static inline pte_t pte_mkdirty(pte_t pte) > > static inline pte_t pte_mkwrite(pte_t pte) > { > - pte_val(pte) |= (_PAGE_WRITE | _PAGE_DIRTY); > + pte_val(pte) |= _PAGE_WRITE; > + if (pte_val(pte) & _PAGE_MODIFIED) > + pte_val(pte) |= _PAGE_DIRTY; > return pte; > } > > @@ -457,7 +459,9 @@ static inline int pmd_write(pmd_t pmd) > > static inline pmd_t pmd_mkwrite(pmd_t pmd) > { > - pmd_val(pmd) |= (_PAGE_WRITE | _PAGE_DIRTY); > + pmd_val(pmd) |= _PAGE_WRITE; > + if (pmd_val(pmd) & _PAGE_MODIFIED) > + pmd_val(pmd) |= _PAGE_DIRTY; > return pmd; > } > > -- > 2.31.1 >
-- Best Regards Guo Ren
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