Re: [PATCH] target/riscv: Fix mret exception cause when no pmp rule is configured

[Wilfred Mallawa]

On Mon, 2022-12-05 at 14:53 +0800, Bin Meng wrote:
> The priv spec v1.12 says:
> 
>   If no PMP entry matches an M-mode access, the access succeeds. If
>   no PMP entry matches an S-mode or U-mode access, but at least one
>   PMP entry is implemented, the access fails. Failed accesses
> generate
>   an instruction, load, or store access-fault exception.
> 
> At present the exception cause is set to 'illegal instruction' but
> should have been 'instruction access fault'.
> 
> Fixes: d102f19a2085 ("target/riscv/pmp: Raise exception if no PMP
> entry is configured")
> Signed-off-by: Bin Meng <bmeng@tinylab.org>
> ---
> 
>  target/riscv/op_helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
> 
> diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
> index 09f1f5185d..d7af7f056b 100644
> --- a/target/riscv/op_helper.c
> +++ b/target/riscv/op_helper.c
> @@ -202,7 +202,7 @@ target_ulong helper_mret(CPURISCVState *env)
>  
>      if (riscv_feature(env, RISCV_FEATURE_PMP) &&
>          !pmp_get_num_rules(env) && (prev_priv != PRV_M)) {
> -        riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST,
> GETPC());
> +        riscv_raise_exception(env, RISCV_EXCP_INST_ACCESS_FAULT,
> GETPC());
>      }
>  
>      target_ulong prev_virt = get_field(env->mstatus, MSTATUS_MPV);