Re: [PATCH] target/riscv: Add User CSRs read-only check

[Bin Meng]

On Mon, Aug 9, 2021 at 3:09 PM LIU Zhiwei <zhiwei_liu@c-sky.com> wrote:
>

nits: please write something in the commit message

> Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
> ---
>  target/riscv/csr.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 9a4ed18ac5..ea62d9e653 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -1422,11 +1422,11 @@ RISCVException riscv_csrrw(CPURISCVState *env, int 
> csrno,
>      RISCVException ret;
>      target_ulong old_value;
>      RISCVCPU *cpu = env_archcpu(env);
> +    int read_only = get_field(csrno, 0xC00) == 3;
>
>      /* check privileges and return -1 if check fails */
>  #if !defined(CONFIG_USER_ONLY)
>      int effective_priv = env->priv;
> -    int read_only = get_field(csrno, 0xC00) == 3;
>
>      if (riscv_has_ext(env, RVH) &&
>          env->priv == PRV_S &&
> @@ -1443,6 +1443,10 @@ RISCVException riscv_csrrw(CPURISCVState *env, int 
> csrno,
>          (!env->debugger && (effective_priv < get_field(csrno, 0x300)))) {
>          return RISCV_EXCP_ILLEGAL_INST;
>      }
> +#else
> +    if (write_mask && read_only) {

This can be merged by the !CONFIG_USER_ONLY case.

> +        return -RISCV_EXCP_ILLEGAL_INST;
> +    }
>  #endif
>
>      /* ensure the CSR extension is enabled. */

Regards,
Bin