[PATCH 2/3] lib: sbi: Fixup tinst for exceptions in sbi_misaligned_*()

[Anup Patel]

On Thu, Jun 9, 2022 at 12:38 PM dramforever <dramforever at live.com> wrote:
>
> If there is an exception while emulating a misaligned load/store, fixup
> uptrap.tinst before redirecting. Otherwise, HS-mode software may receive
> an htinst describing the lbu/sb instruction that faulted during
> emulation[1].
>
> [1]: https://github.com/riscv-software-src/opensbi/issues/258
>
> Signed-off-by: dramforever <dramforever at live.com>

Looks good to me.

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

Regards,
Anup

> ---
>  lib/sbi/sbi_misaligned_ldst.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/lib/sbi/sbi_misaligned_ldst.c b/lib/sbi/sbi_misaligned_ldst.c
> index c879ce7..fd11798 100644
> --- a/lib/sbi/sbi_misaligned_ldst.c
> +++ b/lib/sbi/sbi_misaligned_ldst.c
> @@ -22,6 +22,18 @@ union reg_data {
>         u64 data_u64;
>  };
>
> +static ulong sbi_misaligned_tinst_fixup(ulong orig_tinst, ulong new_tinst,
> +                                       ulong addr_offset)
> +{
> +       if (new_tinst == INSN_PSEUDO_VS_LOAD ||
> +           new_tinst == INSN_PSEUDO_VS_STORE)
> +               return new_tinst;
> +       else if (orig_tinst == 0)
> +               return 0UL;
> +       else
> +               return orig_tinst | (addr_offset << SH_RS1);
> +}
> +
>  int sbi_misaligned_load_handler(ulong addr, ulong tval2, ulong tinst,
>                                 struct sbi_trap_regs *regs)
>  {
> @@ -126,6 +138,8 @@ int sbi_misaligned_load_handler(ulong addr, ulong tval2, ulong tinst,
>                                                 &uptrap);
>                 if (uptrap.cause) {
>                         uptrap.epc = regs->mepc;
> +                       uptrap.tinst = sbi_misaligned_tinst_fixup(
> +                               tinst, uptrap.tinst, i);
>                         return sbi_trap_redirect(regs, &uptrap);
>                 }
>         }
> @@ -238,6 +252,8 @@ int sbi_misaligned_store_handler(ulong addr, ulong tval2, ulong tinst,
>                              &uptrap);
>                 if (uptrap.cause) {
>                         uptrap.epc = regs->mepc;
> +                       uptrap.tinst = sbi_misaligned_tinst_fixup(
> +                               tinst, uptrap.tinst, i);
>                         return sbi_trap_redirect(regs, &uptrap);
>                 }
>         }
> --
> 2.36.0
>
>
> --
> opensbi mailing list
> opensbi at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/opensbi