Messages in this thread | | | Subject | Re: [PATCH] MIPS: update tlb even if pte entry has no change | From | maobibo <> | Date | Thu, 14 May 2020 19:40:20 +0800 |
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On 05/14/2020 05:33 PM, Mike Rapoport wrote: > On Thu, May 14, 2020 at 10:17:57AM +0800, Bibo Mao wrote: >> From: bibo mao <maobibo@loongson.cn> >> >> If there are two threads reading the same memory and tlb miss happens, >> one thread fills pte entry, the other reads new pte value during page fault >> handling. PTE value may be updated before page faul, so the process need >> need update tlb still. >> >> Also this patch define flush_tlb_fix_spurious_fault as empty, since it not >> necessary to flush the page for all CPUs > > I'm not familiar enough with MIPS TLB workings, but it seems that adding > a MIPS version of ptep_set_access_flags() and relaxing > flush_tlb_fix_spurious_fault() are two separate patches.
Well, will split it into two patches.
regards bibo, mao > >> Signed-off-by: Bibo Mao <maobibo@loongson.cn> >> --- >> arch/mips/include/asm/pgtable.h | 20 ++++++++++++++++++++ >> 1 file changed, 20 insertions(+) >> >> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h >> index aab0ec1..d0a4940 100644 >> --- a/arch/mips/include/asm/pgtable.h >> +++ b/arch/mips/include/asm/pgtable.h >> @@ -635,6 +635,26 @@ static inline pmd_t pmd_mknotpresent(pmd_t pmd) >> return pmd; >> } >> >> +#define flush_tlb_fix_spurious_fault(vma, address) do { } while (0) >> + >> +#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS >> +int ptep_set_access_flags(struct vm_area_struct *vma, >> + unsigned long address, pte_t *ptep, >> + pte_t entry, int dirty) >> +{ >> + int changed = !pte_same(*ptep, entry); >> + >> + if (changed) >> + set_pte_at(vma->vm_mm, address, ptep, entry); >> + else >> + /* update tlb with latest pte entry still, tlb entry is old >> + * since there is page fault >> + */ >> + update_mmu_cache(vma, address, ptep); >> + >> + return changed; >> +} >> + >> /* >> * The generic version pmdp_huge_get_and_clear uses a version of pmd_clear() with a >> * different prototype. >> -- >> 1.8.3.1 >> >
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