Re: [PATCH v6 1/3] target/riscv: Add functions for common matching conditions of trigger

[Alistair Francis]

On Wed, Jun 26, 2024 at 11:25 PM Alvin Chang via <qemu-devel@nongnu.org> wrote:
>
> From: Alvin Chang via <qemu-devel@nongnu.org>

Something is still strange with your From

Alistair

>
> According to RISC-V Debug specification version 0.13 [1] (also applied
> to version 1.0 [2] but it has not been ratified yet), there are several
> common matching conditions before firing a trigger, including the
> enabled privilege levels of the trigger.
>
> This commit adds trigger_common_match() to prepare the common matching
> conditions for the type 2/3/6 triggers. For now, we just implement
> trigger_priv_match() to check if the enabled privilege levels of the
> trigger match CPU's current privilege level.
>
> Remove the related code in riscv_cpu_debug_check_breakpoint() and invoke
> trigger_common_match() to check the privilege levels of the type 2 and
> type 6 triggers for the breakpoints.
>
> This commit also changes the behavior of looping the triggers. In
> previous implementation, if we have a type 2 trigger and
> env->virt_enabled is true, we directly return false to stop the loop.
> Now we keep looping all the triggers until we find a matched trigger.
>
> Only the execution bit and the executed PC should be futher checked in
> riscv_cpu_debug_check_breakpoint().
>
> [1]: https://github.com/riscv/riscv-debug-spec/releases/tag/task_group_vote
> [2]: https://github.com/riscv/riscv-debug-spec/releases/tag/1.0.0-rc1-asciidoc
>
> Signed-off-by: Alvin Chang <alvinga@andestech.com>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  target/riscv/debug.c | 101 +++++++++++++++++++++++++++++++++----------
>  1 file changed, 78 insertions(+), 23 deletions(-)
>
> diff --git a/target/riscv/debug.c b/target/riscv/debug.c
> index b110370e..11125f33 100644
> --- a/target/riscv/debug.c
> +++ b/target/riscv/debug.c
> @@ -241,6 +241,76 @@ static void do_trigger_action(CPURISCVState *env, 
> target_ulong trigger_index)
>      }
>  }
>
> +/*
> + * Check the privilege level of specific trigger matches CPU's current 
> privilege
> + * level.
> + */
> +static bool trigger_priv_match(CPURISCVState *env, trigger_type_t type,
> +                               int trigger_index)
> +{
> +    target_ulong ctrl = env->tdata1[trigger_index];
> +
> +    switch (type) {
> +    case TRIGGER_TYPE_AD_MATCH:
> +        /* type 2 trigger cannot be fired in VU/VS mode */
> +        if (env->virt_enabled) {
> +            return false;
> +        }
> +        /* check U/S/M bit against current privilege level */
> +        if ((ctrl >> 3) & BIT(env->priv)) {
> +            return true;
> +        }
> +        break;
> +    case TRIGGER_TYPE_AD_MATCH6:
> +        if (env->virt_enabled) {
> +            /* check VU/VS bit against current privilege level */
> +            if ((ctrl >> 23) & BIT(env->priv)) {
> +                return true;
> +            }
> +        } else {
> +            /* check U/S/M bit against current privilege level */
> +            if ((ctrl >> 3) & BIT(env->priv)) {
> +                return true;
> +            }
> +        }
> +        break;
> +    case TRIGGER_TYPE_INST_CNT:
> +        if (env->virt_enabled) {
> +            /* check VU/VS bit against current privilege level */
> +            if ((ctrl >> 25) & BIT(env->priv)) {
> +                return true;
> +            }
> +        } else {
> +            /* check U/S/M bit against current privilege level */
> +            if ((ctrl >> 6) & BIT(env->priv)) {
> +                return true;
> +            }
> +        }
> +        break;
> +    case TRIGGER_TYPE_INT:
> +    case TRIGGER_TYPE_EXCP:
> +    case TRIGGER_TYPE_EXT_SRC:
> +        qemu_log_mask(LOG_UNIMP, "trigger type: %d is not supported\n", 
> type);
> +        break;
> +    case TRIGGER_TYPE_NO_EXIST:
> +    case TRIGGER_TYPE_UNAVAIL:
> +        qemu_log_mask(LOG_GUEST_ERROR, "trigger type: %d does not exist\n",
> +                      type);
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +
> +    return false;
> +}
> +
> +/* Common matching conditions for all types of the triggers. */
> +static bool trigger_common_match(CPURISCVState *env, trigger_type_t type,
> +                                 int trigger_index)
> +{
> +    return trigger_priv_match(env, type, trigger_index);
> +}
> +
>  /* type 2 trigger */
>
>  static uint32_t type2_breakpoint_size(CPURISCVState *env, target_ulong ctrl)
> @@ -785,22 +855,18 @@ bool riscv_cpu_debug_check_breakpoint(CPUState *cs)
>          for (i = 0; i < RV_MAX_TRIGGERS; i++) {
>              trigger_type = get_trigger_type(env, i);
>
> +            if (!trigger_common_match(env, trigger_type, i)) {
> +                continue;
> +            }
> +
>              switch (trigger_type) {
>              case TRIGGER_TYPE_AD_MATCH:
> -                /* type 2 trigger cannot be fired in VU/VS mode */
> -                if (env->virt_enabled) {
> -                    return false;
> -                }
> -
>                  ctrl = env->tdata1[i];
>                  pc = env->tdata2[i];
>
>                  if ((ctrl & TYPE2_EXEC) && (bp->pc == pc)) {
> -                    /* check U/S/M bit against current privilege level */
> -                    if ((ctrl >> 3) & BIT(env->priv)) {
> -                        env->badaddr = pc;
> -                        return true;
> -                    }
> +                    env->badaddr = pc;
> +                    return true;
>                  }
>                  break;
>              case TRIGGER_TYPE_AD_MATCH6:
> @@ -808,19 +874,8 @@ bool riscv_cpu_debug_check_breakpoint(CPUState *cs)
>                  pc = env->tdata2[i];
>
>                  if ((ctrl & TYPE6_EXEC) && (bp->pc == pc)) {
> -                    if (env->virt_enabled) {
> -                        /* check VU/VS bit against current privilege level */
> -                        if ((ctrl >> 23) & BIT(env->priv)) {
> -                            env->badaddr = pc;
> -                            return true;
> -                        }
> -                    } else {
> -                        /* check U/S/M bit against current privilege level */
> -                        if ((ctrl >> 3) & BIT(env->priv)) {
> -                            env->badaddr = pc;
> -                            return true;
> -                        }
> -                    }
> +                    env->badaddr = pc;
> +                    return true;
>                  }
>                  break;
>              default:
> --
> 2.34.1
>
>