Re: What's the correct way to implement rfi and related instruction.

[Cédric Le Goater]

On 1/7/21 8:14 PM, 罗勇刚(Yonggang Luo) wrote:
> This is the first patch,:
> It's store MSR bits differntly for different rfi instructions:
> [Qemu-devel] [PATCH] target-ppc: fix RFI by clearing some bits of MSR
> https://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02999.html 
> <https://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02999.html>
> Comes from  target-ppc: fix RFI by clearing some bits of MSR
> SHA-1: c3d420ead1aee9fcfd12be11cbdf6b1620134773
>  target-ppc/op_helper.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> ```
> diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
> index 8f2ee986bb..3c3aa60bc3 100644
> --- a/target-ppc/op_helper.c
> +++ b/target-ppc/op_helper.c
> @@ -1646,20 +1646,20 @@ static inline void do_rfi(target_ulong nip, 
> target_ulong msr,
>  void helper_rfi (void)
>  {
>      do_rfi(env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -           ~((target_ulong)0x0), 1);
> +           ~((target_ulong)0x783F0000), 1);
>  }
>  
>  #if defined(TARGET_PPC64)
>  void helper_rfid (void)
>  {
>      do_rfi(env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -           ~((target_ulong)0x0), 0);
> +           ~((target_ulong)0x783F0000), 0);
>  }
>  
>  void helper_hrfid (void)
>  {
>      do_rfi(env->spr[SPR_HSRR0], env->spr[SPR_HSRR1],
> -           ~((target_ulong)0x0), 0);
> +           ~((target_ulong)0x783F0000), 0);
>  }
>  #endif
>  #endif
> ```
> 
> This is the second patch,:
> it's remove the parameter  `target_ulong msrm, int keep_msrh`
> Comes from ppc: Fix rfi/rfid/hrfi/... emulation
> SHA-1: a2e71b28e832346409efc795ecd1f0a2bcb705a3
> ```
>  target-ppc/excp_helper.c | 51 
> +++++++++++++++++++-----------------------------
>  1 file changed, 20 insertions(+), 31 deletions(-)
> 
> diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c
> index 30e960e30b..aa0b63f4b0 100644
> --- a/target-ppc/excp_helper.c
> +++ b/target-ppc/excp_helper.c
> @@ -922,25 +922,20 @@ void helper_store_msr(CPUPPCState *env, target_ulong 
> val)
>      }
>  }
>  
> -static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong 
> msr,
> -                          target_ulong msrm, int keep_msrh)
> +static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong 
> msr)
>  {
>      CPUState *cs = CPU(ppc_env_get_cpu(env));
>  
> +    /* MSR:POW cannot be set by any form of rfi */
> +    msr &= ~(1ULL << MSR_POW);
> +
>  #if defined(TARGET_PPC64)
> -    if (msr_is_64bit(env, msr)) {
> -        nip = (uint64_t)nip;
> -        msr &= (uint64_t)msrm;
> -    } else {
> +    /* Switching to 32-bit ? Crop the nip */
> +    if (!msr_is_64bit(env, msr)) {
>          nip = (uint32_t)nip;
> -        msr = (uint32_t)(msr & msrm);
> -        if (keep_msrh) {
> -            msr |= env->msr & ~((uint64_t)0xFFFFFFFF);
> -        }
>      }
>  #else
>      nip = (uint32_t)nip;
> -    msr &= (uint32_t)msrm;
>  #endif
>      /* XXX: beware: this is false if VLE is supported */
>      env->nip = nip & ~((target_ulong)0x00000003);
> @@ -959,26 +954,24 @@ static inline void do_rfi(CPUPPCState *env, 
> target_ulong nip, target_ulong msr,
>  
>  void helper_rfi(CPUPPCState *env)
>  {
> -    if (env->excp_model == POWERPC_EXCP_BOOKE) {
> -        do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -               ~((target_ulong)0), 0);
> -    } else {
> -        do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -               ~((target_ulong)0x783F0000), 1);
> -    }
> +    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1] & 0xfffffffful);
>  }
>  
> +#define MSR_BOOK3S_MASK
>  #if defined(TARGET_PPC64)
>  void helper_rfid(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -           ~((target_ulong)0x783F0000), 0);
> +    /* The architeture defines a number of rules for which bits
> +     * can change but in practice, we handle this in hreg_store_msr()
> +     * which will be called by do_rfi(), so there is no need to filter
> +     * here
> +     */
> +    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1]);
>  }
>  
>  void helper_hrfid(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_HSRR0], env->spr[SPR_HSRR1],
> -           ~((target_ulong)0x783F0000), 0);
> +    do_rfi(env, env->spr[SPR_HSRR0], env->spr[SPR_HSRR1]);
>  }
>  #endif
>  
> @@ -986,28 +979,24 @@ void helper_hrfid(CPUPPCState *env)
>  /* Embedded PowerPC specific helpers */
>  void helper_40x_rfci(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_40x_SRR2], env->spr[SPR_40x_SRR3],
> -           ~((target_ulong)0xFFFF0000), 0);
> +    do_rfi(env, env->spr[SPR_40x_SRR2], env->spr[SPR_40x_SRR3]);
>  }
>  
>  void helper_rfci(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_BOOKE_CSRR0], env->spr[SPR_BOOKE_CSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_CSRR0], env->spr[SPR_BOOKE_CSRR1]);
>  }
>  
>  void helper_rfdi(CPUPPCState *env)
>  {
>      /* FIXME: choose CSRR1 or DSRR1 based on cpu type */
> -    do_rfi(env, env->spr[SPR_BOOKE_DSRR0], env->spr[SPR_BOOKE_DSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_DSRR0], env->spr[SPR_BOOKE_DSRR1]);
>  }
>  
>  void helper_rfmci(CPUPPCState *env)
>  {
>      /* FIXME: choose CSRR1 or MCSRR1 based on cpu type */
> -    do_rfi(env, env->spr[SPR_BOOKE_MCSRR0], env->spr[SPR_BOOKE_MCSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_MCSRR0], env->spr[SPR_BOOKE_MCSRR1]);
>  }
>  #endif
>  
> @@ -1045,7 +1034,7 @@ void helper_td(CPUPPCState *env, target_ulong arg1, 
> target_ulong arg2,
>  
>  void helper_rfsvc(CPUPPCState *env)
>  {
> -    do_rfi(env, env->lr, env->ctr, 0x0000FFFF, 0);
> +    do_rfi(env, env->lr, env->ctr & 0x0000FFFF);
>  }
>  
>  /* Embedded.Processor Control */
> ```
> 
> And of cause, the second patch fixes some problem, but also cause new 
> problem, 
> how to implement these instruction properly?

What are the new problems  ? 

C.

> 
> 
> 
> --
>          此致
> 礼
> 罗勇刚
> Yours
>     sincerely,
> Yonggang Luo