Re: [PATCH v3 4/6] target/riscv: Add support to record CTR entries.

[Richard Henderson]

On 11/4/24 21:51, Rajnesh Kanwal wrote:
> +/*
> + * Indirect calls
> + * - jalr x1, rs where rs != x5;
> + * - jalr x5, rs where rs != x1;
> + * - c.jalr rs1 where rs1 != x5;
> + *
> + * Indirect jumps
> + * - jalr x0, rs where rs != x1 and rs != x5;
> + * - c.jr rs1 where rs1 != x1 and rs1 != x5.
> + *
> + * Returns
> + * - jalr rd, rs where (rs == x1 or rs == x5) and rd != x1 and rd != x5;
> + * - c.jr rs1 where rs1 == x1 or rs1 == x5.
> + *
> + * Co-routine swap
> + * - jalr x1, x5;
> + * - jalr x5, x1;
> + * - c.jalr x5.
> + *
> + * Other indirect jumps
> + * - jalr rd, rs where rs != x1, rs != x5, rd != x0, rd != x1 and rd != x5.
> + */
> +void helper_ctr_jalr(CPURISCVState *env, target_ulong src, target_ulong dest,
> +                     target_ulong rd, target_ulong rs1)
> +{
> +    target_ulong curr_priv = env->priv;
> +    bool curr_virt = env->virt_enabled;
> +
> +    if ((rd == 1 && rs1 != 5) || (rd == 5 && rs1 != 1)) {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_INDIRECT_CALL,
> +                            curr_priv, curr_virt);
> +    } else if (rd == 0 && rs1 != 1 && rs1 != 5) {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_INDIRECT_JUMP,
> +                            curr_priv, curr_virt);
> +    } else if ((rs1 == 1 || rs1 == 5) && (rd != 1 && rd != 5)) {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_RETURN,
> +                            curr_priv, curr_virt);
> +    } else if ((rs1 == 1 && rd == 5) || (rs1 == 5 && rd == 1)) {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_CO_ROUTINE_SWAP,
> +                            curr_priv, curr_virt);
> +    } else {
> +        riscv_ctr_add_entry(env, src, dest,
> +                            CTRDATA_TYPE_OTHER_INDIRECT_JUMP, curr_priv,
> +                            curr_virt);
> +    }
> +}

All of these if's are constant at translation time.
You should move this decision tree...

> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -569,6 +569,16 @@ static void gen_jal(DisasContext *ctx, int rd, 
> target_ulong imm)
>          }
>      }
>  
> +#ifndef CONFIG_USER_ONLY
> +    if (ctx->cfg_ptr->ext_smctr || ctx->cfg_ptr->ext_ssctr) {
> +        TCGv dest = tcg_constant_tl(ctx->base.pc_next + imm);
> +        TCGv src = tcg_constant_tl(ctx->base.pc_next);
> +        TCGv tcg_rd = tcg_constant_tl((target_ulong)rd);
> +
> +        gen_helper_ctr_jal(tcg_env, src, dest, tcg_rd);
> +    }
> +#endif

... here.  All you need is to expose helper_ctr_add_entry().

With that,

> +void helper_ctr_popret(CPURISCVState *env, target_ulong src, target_ulong dest)
> +{
> +    riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_RETURN,
> +                            env->priv, env->virt_enabled);
> +}
> +
> +void helper_ctr_branch(CPURISCVState *env, target_ulong src, target_ulong dest,
> +                       target_ulong branch_taken)
> +{
> +    target_ulong curr_priv = env->priv;
> +    bool curr_virt = env->virt_enabled;
> +
> +    if (branch_taken) {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_TAKEN_BRANCH,
> +                            curr_priv, curr_virt);
> +    } else {
> +        riscv_ctr_add_entry(env, src, dest, CTRDATA_TYPE_NONTAKEN_BRANCH,
> +                            curr_priv, curr_virt);
> +    }
> +}

these can go away, simply passing the correct CTRDATA_* constant at the right 
place.


r~