Re: [PATCH] target/riscv: Check PMP rules num before propagation

[LIU Zhiwei]

0

On 2021/11/17 上午8:03, Alistair Francis wrote:
> On Wed, Nov 17, 2021 at 1:12 AM LIU Zhiwei <zhiwei_liu@c-sky.com> wrote:
> > If PMP rules number is zero, it should not influence the TLB entry for
> > M-mode program.
> This doesn't sound right. From what I can tell if we have no rules
> pmp_is_range_in_tlb() shouldn't have an effect on the tlb_size. What
> error are you seeing?

When address is in [0-4K] and no pmp rule configured,  the tlb_size will 
be set to 1.

This  is caused by pmp_get_tlb_size return a value 1.

if (pmp_sa >= tlb_sa && pmp_ea <= tlb_ea) {
         return pmp_ea - pmp_sa + 1;

}

Here pmp_sa == 0 and pmp_ea == 0.

Thanks,
Zhiwei

> Alistair
>
> > Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
> > ---
> >   target/riscv/cpu_helper.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> > index 9eeed38c7e..48da872d39 100644
> > --- a/target/riscv/cpu_helper.c
> > +++ b/target/riscv/cpu_helper.c
> > @@ -376,7 +376,7 @@ static int get_physical_address_pmp(CPURISCVState *env, int 
> > *prot,
> >       }
> >
> >       *prot = pmp_priv_to_page_prot(pmp_priv);
> > -    if (tlb_size != NULL) {
> > +    if ((tlb_size != NULL) && pmp_get_num_rules(env)) {
> >           if (pmp_is_range_in_tlb(env, addr & ~(*tlb_size - 1), &tlb_size_pmp)) 
> > {
> >               *tlb_size = tlb_size_pmp;
> >           }
> > --
> > 2.25.1