Re: [PATCH v12 04/20] target/riscv: save and restore elp state on priv transitions

[Richard Henderson <richard.henderson@linaro.org>]

On 8/30/24 09:34, Deepak Gupta wrote:
> elp state is recorded in *status on trap entry (less privilege to higher
> privilege) and restored in elp from *status on trap exit (higher to less
> privilege).
> 
> Additionally this patch introduces a forward cfi helper function to
> determine if current privilege has forward cfi is enabled or not based on
> *envcfg (for U, VU, S, VU, HS) or mseccfg csr (for M). For qemu-user, a
> new field `ufcfien` is introduced which is by default set to false and
> helper function returns value deposited in `ufcfien` for qemu-user.

Patch description needs updating to remove ufcfien.

> +bool cpu_get_fcfien(CPURISCVState *env)
> +{
> +    /* no cfi extension, return false */
> +    if (!env_archcpu(env)->cfg.ext_zicfilp) {
> +        return false;
> +    }
> +
> +    switch (env->priv) {
> +    case PRV_U:
> +        if (riscv_has_ext(env, RVS)) {
> +            return env->senvcfg & SENVCFG_LPE;
> +        }
> +        return env->menvcfg & MENVCFG_LPE;
> +#ifndef CONFIG_USER_ONLY
> +    case PRV_S:
> +        if (env->virt_enabled) {
> +            return env->henvcfg & HENVCFG_LPE;
> +        }
> +        return env->menvcfg & MENVCFG_LPE;
> +    case PRV_M:
> +        return env->mseccfg & MSECCFG_MLPE;
> +#endif
> +    default:
> +        g_assert_not_reached();
> +    }
> +}

Excellent, thanks.


r~