[PATCH] Support TOR mode in pmp_set

[Anup Patel]

On Thu, Sep 26, 2024 at 6:47 PM Pope B.Lei <popeblei at gmail.com> wrote:

TOR mode requires two PMP entries to mark the start and end of a region.

Please refer to my response on "[PATCH 0/3] Add support for tor type pmp"
thread.

>
> Signed-off-by: Pope B.Lei <popeblei at gmail.com>
> ---
>  include/sbi/riscv_encoding.h |  2 ++
>  lib/sbi/riscv_asm.c          | 19 ++++++++++++++++---
>  2 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index 980abdb..387c011 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -154,6 +154,8 @@
>  #define PMP_A_NAPOT                    _UL(0x18)
>  #define PMP_L                          _UL(0x80)
>
> +#define PMP_USE_TOR                    _UL(0x00)
> +
>  #define PMP_SHIFT                      2
>  #define PMP_COUNT                      64
>  #if __riscv_xlen == 64
> diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> index c7d75ac..4518b2c 100644
> --- a/lib/sbi/riscv_asm.c
> +++ b/lib/sbi/riscv_asm.c
> @@ -309,7 +309,7 @@ int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
>         unsigned long addrmask, pmpaddr;
>
>         /* check parameters */
> -       if (n >= PMP_COUNT || log2len > __riscv_xlen || log2len < PMP_SHIFT)
> +       if (n >= PMP_COUNT || log2len > __riscv_xlen || (log2len < PMP_SHIFT && log2len != PMP_USE_TOR ))
>                 return SBI_EINVAL;
>
>         /* calculate PMP register and offset */
> @@ -326,13 +326,26 @@ int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
>
>         /* encode PMP config */
>         prot &= ~PMP_A;
> -       prot |= (log2len == PMP_SHIFT) ? PMP_A_NA4 : PMP_A_NAPOT;
> +
> +       switch(log2len){
> +               case PMP_USE_TOR:{
> +                       prot |= PMP_A_TOR;
> +                       break;
> +               }
> +               case PMP_SHIFT:{
> +                       prot |= PMP_A_NA4;
> +                       break;
> +               }
> +               default:
> +                       prot |= PMP_A_NAPOT;
> +       }
> +
>         cfgmask = ~(0xffUL << pmpcfg_shift);
>         pmpcfg  = (csr_read_num(pmpcfg_csr) & cfgmask);
>         pmpcfg |= ((prot << pmpcfg_shift) & ~cfgmask);
>
>         /* encode PMP address */
> -       if (log2len == PMP_SHIFT) {
> +       if (log2len == PMP_SHIFT || log2len == PMP_USE_TOR) {

This is only programming one PMP entry but for TOR we need
two PMP entries per-region.

Also, what about pmp_get() ?

In general, let's avoid TOR PMP entries as much as possible.

Regards,
Anup


>                 pmpaddr = (addr >> PMP_SHIFT);
>         } else {
>                 if (log2len == __riscv_xlen) {
> --
> 2.35.2.windows.1
>
>
> --
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