[PATCH 4/7] lib: sbi: probe PMP allowed addr from first usable PMP

[Anup Patel]

On Fri, Dec 8, 2023 at 3:34 AM Yangyu Chen <cyy at cyyself.name> wrote:
>
> Some PMPs may be locked before OpenSBI starts. Probe allowed addr only
> from pmpaddr0 may get the wrong result since it may be locked thus the
> value can not be changed.
>
> Signed-off-by: Yangyu Chen <cyy at cyyself.name>
> ---
>  lib/sbi/sbi_hart.c | 29 +++++++++--------------------
>  1 file changed, 9 insertions(+), 20 deletions(-)
>
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index f18a6bc..f8f7b82 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -784,23 +784,10 @@ static unsigned long hart_pmp_probe_reserved(unsigned int nr_pmps)
>         return pmpcfg_locked;
>  }
>
> -static unsigned long hart_pmp_get_allowed_addr(void)
> +static unsigned long hart_pmp_get_allowed_addr(unsigned int n)
>  {
> -       unsigned long val = 0;
> -       struct sbi_trap_info trap = {0};
> -
> -       csr_write_allowed(CSR_PMPCFG0, (ulong)&trap, 0);
> -       if (trap.cause)
> -               return 0;
> -
> -       csr_write_allowed(CSR_PMPADDR0, (ulong)&trap, PMP_ADDR_MASK);
> -       if (!trap.cause) {
> -               val = csr_read_allowed(CSR_PMPADDR0, (ulong)&trap);
> -               if (trap.cause)
> -                       val = 0;
> -       }
> -
> -       return val;
> +       csr_write_num(CSR_PMPADDR0 + n, PMP_ADDR_MASK);
> +       return csr_read_num(CSR_PMPADDR0 + n);
>  }
>
>  static int hart_mhpm_get_allowed_bits(void)
> @@ -926,10 +913,12 @@ __pmp_count_probed:
>          * Detect the allowed address bits & granularity. At least PMPADDR0
>          * should be implemented.
>          */
> -       val = hart_pmp_get_allowed_addr();
> -       if (val) {
> -               hfeatures->pmp_gran =  1 << (sbi_ffs(val) + 2);
> -               hfeatures->pmp_addr_bits = sbi_fls(val) + 1;
> +       if (hfeatures->pmp_reserved != hfeatures->pmp_count) {

This must check "hfeatures->pmp_reserved < hfeatures->pmp_count".

> +               val = hart_pmp_get_allowed_addr(hfeatures->pmp_reserved);
> +               if (val) {
> +                       hfeatures->pmp_gran =  1 << (sbi_ffs(val) + 2);
> +                       hfeatures->pmp_addr_bits = sbi_fls(val) + 1;
> +               }
>         }
>         /* Detect number of MHPM counters */
>         __check_hpm_csr(CSR_MHPMCOUNTER3, mhpm_mask);
> --
> 2.43.0
>
>
> --
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Regards,
Anup