Re: [PATCH v2 9/9] target/riscv: Use a smaller guess size for no-MMU PMP

[Bin Meng]

On Fri, May 8, 2020 at 3:29 AM Alistair Francis
<address@hidden> wrote:
>
> Signed-off-by: Alistair Francis <address@hidden>
> ---
>  target/riscv/pmp.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index 0e6b640fbd..5aba4d13ea 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -233,12 +233,21 @@ bool pmp_hart_has_privs(CPURISCVState *env, 
> target_ulong addr,
>          return true;
>      }
>
> -    /*
> -     * if size is unknown (0), assume that all bytes
> -     * from addr to the end of the page will be accessed.
> -     */
>      if (size == 0) {
> -        pmp_size = -(addr | TARGET_PAGE_MASK);
> +        if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
> +            /*
> +             * if size is unknown (0), assume that all bytes
> +             * from addr to the end of the page will be accessed.
> +             */
> +            pmp_size = -(addr | TARGET_PAGE_MASK);
> +        } else {
> +            /*
> +             * If size is unknown (0) and we don't have an MMU,
> +             * just guess the size as the xlen as we don't want to
> +             * access an entire page worth.
> +             */

It looks the comment does not match the code logic. This else branch
is the MMU branch.

> +            pmp_size = sizeof(target_ulong);
> +        }
>      } else {
>          pmp_size = size;
>      }
> --

Regards,
Bin