Messages in this thread | | | Date | Tue, 04 Aug 2020 19:03:06 -0700 (PDT) | Subject | Re: [PATCH] riscv: Add sfence.vma after page table changed | From | Palmer Dabbelt <> |
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On Mon, 03 Aug 2020 20:29:32 PDT (-0700), anup@brainfault.org wrote: > On Tue, Aug 4, 2020 at 8:32 AM Greentime Hu <greentime.hu@sifive.com> wrote: >> >> This patch addes local_flush_tlb_page(addr) to use sfence.vma after the > > s/addes/adds > >> page table changed. That address will be used immediately in >> memset(nextp, 0, PAGE_SIZE) to cause this issue so we should add the >> sfence.vma before we use it. > > Alternate version of this commit description can be: > > Invalidate local TLB after both set_pet() and clear_pte() because the > address can be used immediately after page table change. > >> Fixes: f2c17aabc917 ("RISC-V: Implement compile-time fixed mappings") >> >> Reported-by: Syven Wang <syven.wang@sifive.com> >> Signed-off-by: Syven Wang <syven.wang@sifive.com> >> Signed-off-by: Greentime Hu <greentime.hu@sifive.com> >> --- >> arch/riscv/mm/init.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c >> index f4adb3684f3d..29b0f7108054 100644 >> --- a/arch/riscv/mm/init.c >> +++ b/arch/riscv/mm/init.c >> @@ -202,12 +202,11 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot) >> >> ptep = &fixmap_pte[pte_index(addr)]; >> >> - if (pgprot_val(prot)) { >> + if (pgprot_val(prot)) >> set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot)); >> - } else { >> + else >> pte_clear(&init_mm, addr, ptep); >> - local_flush_tlb_page(addr); >> - } >> + local_flush_tlb_page(addr); >> }
arm64 appears to be upgrading all set_pte()s on valid kernel mappings to include the fence. It looks like the message from 7f0b1bf04511 ("arm64: Fix barriers used for page table modifications") is out of date, as I can't find create_mapping() any more. If that was some generic kernel thing then we should probably upgrade ours as well, but if it was arch/arm64/ code then this approach seems fine as __set_fixmap() isn't on the hot path -- I guess this is fine either way, but there may be other issues that the arm64 approach fixes.
Do you guys happen to remember what was going on here?
>> >> static pte_t *__init get_pte_virt(phys_addr_t pa) >> -- >> 2.28.0 >> > > Otherwise looks good to me. > > Reviewed-by: Anup Patel <anup@brainfault.org> > > Regards, > Anup
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