[PATCH 2/6] lib: sbi: Add functions to manipulate PMP entries

[Anup Patel]

On Tue, Jun 20, 2023 at 8:02 PM Himanshu Chauhan
<hchauhan at ventanamicro.com> wrote:
>
> - Add a function to disable a given PMP entry.
> - Add a function to check if a given entry is disabled.
>
> Signed-off-by: Himanshu Chauhan <hchauhan at ventanamicro.com>
> ---
>  include/sbi/riscv_asm.h |  6 ++++++
>  lib/sbi/riscv_asm.c     | 43 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
>
> diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h
> index 1ff36de..2c34635 100644
> --- a/include/sbi/riscv_asm.h
> +++ b/include/sbi/riscv_asm.h
> @@ -181,6 +181,12 @@ int misa_xlen(void);
>  /* Get RISC-V ISA string representation */
>  void misa_string(int xlen, char *out, unsigned int out_sz);
>
> +/* Disable pmp entry at a given index */
> +int pmp_disable(unsigned int n);
> +
> +/* Check if the matching field is set */
> +int is_pmp_entry_mapped(unsigned long entry);
> +
>  int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
>             unsigned long log2len);
>
> diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> index cd56553..0690721 100644
> --- a/lib/sbi/riscv_asm.c
> +++ b/lib/sbi/riscv_asm.c
> @@ -246,6 +246,49 @@ static unsigned long ctz(unsigned long x)
>         return ret;
>  }
>
> +int pmp_disable(unsigned int n)
> +{
> +       int pmpcfg_csr, pmpcfg_shift;
> +       unsigned long cfgmask, pmpcfg;
> +
> +       if (n >= PMP_COUNT)
> +               return SBI_EINVAL;
> +
> +#if __riscv_xlen == 32
> +       pmpcfg_csr   = CSR_PMPCFG0 + (n >> 2);
> +       pmpcfg_shift = (n & 3) << 3;
> +#elif __riscv_xlen == 64
> +       pmpcfg_csr   = (CSR_PMPCFG0 + (n >> 2)) & ~1;
> +       pmpcfg_shift = (n & 7) << 3;
> +#else
> +# error "Unexpected __riscv_xlen"
> +#endif
> +
> +       /* Clear the address matching bits to disable the pmp entry */
> +       cfgmask = ~(0xffUL << pmpcfg_shift);
> +       pmpcfg  = (csr_read_num(pmpcfg_csr) & cfgmask);
> +       pmpcfg &= (~PMP_A << pmpcfg_shift);

This statement is not required because the previous statement
already cleared all config bits of the PMP region.

> +
> +       csr_write_num(pmpcfg_csr, pmpcfg);
> +
> +       return SBI_OK;
> +}
> +
> +int is_pmp_entry_mapped(unsigned long entry)
> +{
> +       unsigned long prot;
> +       unsigned long addr;
> +       unsigned long log2len;
> +
> +       pmp_get(entry, &prot, &addr, &log2len);
> +
> +       /* If address matching bits are non-zero, the entry is enable */
> +       if (prot & PMP_A)
> +               return true;
> +
> +       return false;
> +}
> +
>  int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
>             unsigned long log2len)
>  {
> --
> 2.34.1
>
>
> --
> opensbi mailing list
> opensbi at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/opensbi

Apart from above, this looks good to me.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup