[PATCH v3 2/4] lib: sbi: fwft: add support for SBI_FWFT_MISALIGNED_EXC_DELEG

[Anup Patel]

On Wed, Jun 19, 2024 at 3:13 PM Clément Léger <cleger at rivosinc.com> wrote:
>
> Add support for SBI_FWFT_MISALIGNED_EXC_DELEG withing FWFT support. This
> support allows to delegate misaligned accesses traps.
>
> Signed-off-by: Clément Léger <cleger at rivosinc.com>

LGTM.

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

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  lib/sbi/sbi_fwft.c | 39 ++++++++++++++++++++++++++++++++++++++-
>  lib/sbi/sbi_hsm.c  |  3 +++
>  2 files changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
> index b302b5d..289a344 100644
> --- a/lib/sbi/sbi_fwft.c
> +++ b/lib/sbi/sbi_fwft.c
> @@ -32,6 +32,8 @@ static unsigned long fwft_ptr_offset;
>  #define fwft_set_hart_state_ptr(__scratch, __phs)                      \
>         sbi_scratch_write_type((__scratch), void *, fwft_ptr_offset, (__phs))
>
> +#define MIS_DELEG (1UL << CAUSE_MISALIGNED_LOAD | 1UL << CAUSE_MISALIGNED_STORE)
> +
>  struct fwft_config;
>
>  struct fwft_feature {
> @@ -71,6 +73,33 @@ static bool fwft_is_defined_feature(enum sbi_fwft_feature_t feature)
>         return false;
>  }
>
> +static int fwft_misaligned_delegation_supported(struct fwft_config *conf)
> +{
> +       if (!misa_extension('S'))
> +               return SBI_ENOTSUPP;
> +
> +       return SBI_OK;
> +}
> +
> +static int fwft_set_misaligned_delegation(struct fwft_config *conf,
> +                                        unsigned long value)
> +{
> +       if (value)
> +               csr_set(CSR_MEDELEG, MIS_DELEG);
> +       else
> +               csr_clear(CSR_MEDELEG, MIS_DELEG);
> +
> +       return SBI_OK;
> +}
> +
> +static int fwft_get_misaligned_delegation(struct fwft_config *conf,
> +                                        unsigned long *value)
> +{
> +       *value = (csr_read(CSR_MEDELEG) & MIS_DELEG) != 0;
> +
> +       return SBI_OK;
> +}
> +
>  static struct fwft_config* get_feature_config(enum sbi_fwft_feature_t feature)
>  {
>         int i;
> @@ -148,7 +177,15 @@ int sbi_fwft_get(enum sbi_fwft_feature_t feature, unsigned long *out_val)
>         return conf->feature->get(conf, out_val);
>  }
>
> -static const struct fwft_feature features[] = {};
> +static const struct fwft_feature features[] =
> +{
> +       {
> +               .id = SBI_FWFT_MISALIGNED_EXC_DELEG,
> +               .supported = fwft_misaligned_delegation_supported,
> +               .set = fwft_set_misaligned_delegation,
> +               .get = fwft_get_misaligned_delegation,
> +       },
> +};
>
>  int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
>  {
> diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
> index be48d64..2b23e13 100644
> --- a/lib/sbi/sbi_hsm.c
> +++ b/lib/sbi/sbi_hsm.c
> @@ -44,6 +44,7 @@ struct sbi_hsm_data {
>         unsigned long suspend_type;
>         unsigned long saved_mie;
>         unsigned long saved_mip;
> +       unsigned long saved_medeleg;
>         atomic_t start_ticket;
>  };
>
> @@ -417,6 +418,7 @@ void __sbi_hsm_suspend_non_ret_save(struct sbi_scratch *scratch)
>
>         hdata->saved_mie = csr_read(CSR_MIE);
>         hdata->saved_mip = csr_read(CSR_MIP) & (MIP_SSIP | MIP_STIP);
> +       hdata->saved_medeleg = csr_read(CSR_MEDELEG);
>  }
>
>  static void __sbi_hsm_suspend_non_ret_restore(struct sbi_scratch *scratch)
> @@ -424,6 +426,7 @@ static void __sbi_hsm_suspend_non_ret_restore(struct sbi_scratch *scratch)
>         struct sbi_hsm_data *hdata = sbi_scratch_offset_ptr(scratch,
>                                                             hart_data_offset);
>
> +       csr_write(CSR_MEDELEG, hdata->saved_medeleg);
>         csr_write(CSR_MIE, hdata->saved_mie);
>         csr_set(CSR_MIP, (hdata->saved_mip & (MIP_SSIP | MIP_STIP)));
>  }
> --
> 2.45.2
>
>
> --
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