Re: [PATCH v4 04/20] target/riscv: Extend pc for runtime pc write

[Alistair Francis <alistair23@gmail.com>]

On Fri, Nov 12, 2021 at 2:01 AM LIU Zhiwei <zhiwei_liu@c-sky.com> wrote:
>
> In some cases, we must restore the guest PC to the address of the start of
> the TB, such as when the instruction counter hits zero. So extend pc register
> according to current xlen for these cases.
>
> Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu.c        | 22 +++++++++++++++++++---
>  target/riscv/cpu.h        |  2 ++
>  target/riscv/cpu_helper.c |  2 +-
>  3 files changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index f812998123..0d2d175fa2 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -319,7 +319,12 @@ static void riscv_cpu_set_pc(CPUState *cs, vaddr value)
>  {
>      RISCVCPU *cpu = RISCV_CPU(cs);
>      CPURISCVState *env = &cpu->env;
> -    env->pc = value;
> +
> +    if (cpu_get_xl(env) == MXL_RV32) {
> +        env->pc = (int32_t)value;
> +    } else {
> +        env->pc = value;
> +    }
>  }
>
>  static void riscv_cpu_synchronize_from_tb(CPUState *cs,
> @@ -327,7 +332,13 @@ static void riscv_cpu_synchronize_from_tb(CPUState *cs,
>  {
>      RISCVCPU *cpu = RISCV_CPU(cs);
>      CPURISCVState *env = &cpu->env;
> -    env->pc = tb->pc;
> +    RISCVMXL xl = FIELD_EX32(tb->flags, TB_FLAGS, XL);
> +
> +    if (xl == MXL_RV32) {
> +        env->pc = (int32_t)tb->pc;
> +    } else {
> +        env->pc = tb->pc;
> +    }
>  }
>
>  static bool riscv_cpu_has_work(CPUState *cs)
> @@ -348,7 +359,12 @@ static bool riscv_cpu_has_work(CPUState *cs)
>  void restore_state_to_opc(CPURISCVState *env, TranslationBlock *tb,
>                            target_ulong *data)
>  {
> -    env->pc = data[0];
> +    RISCVMXL xl = FIELD_EX32(tb->flags, TB_FLAGS, XL);
> +    if (xl == MXL_RV32) {
> +        env->pc = (int32_t)data[0];
> +    } else {
> +        env->pc = data[0];
> +    }
>  }
>
>  static void riscv_cpu_reset(DeviceState *dev)
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 0760c0af93..8befff0166 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -420,6 +420,8 @@ static inline RISCVMXL riscv_cpu_mxl(CPURISCVState *env)
>  }
>  #endif
>
> +RISCVMXL cpu_get_xl(CPURISCVState *env);
> +
>  /*
>   * A simplification for VLMAX
>   * = (1 << LMUL) * VLEN / (8 * (1 << SEW))
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 4c048cc266..79aba9c880 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -35,7 +35,7 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
>  #endif
>  }
>
> -static RISCVMXL cpu_get_xl(CPURISCVState *env)
> +RISCVMXL cpu_get_xl(CPURISCVState *env)
>  {
>  #if defined(TARGET_RISCV32)
>      return MXL_RV32;
> --
> 2.25.1
>
>