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

["罗勇刚(Yonggang Luo)" <luoyonggang@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 9363 bytes --]

On Fri, Jan 8, 2021 at 2:02 AM Cédric Le Goater <clg@kaod.org> wrote:
>
> On 1/8/21 5:21 AM, 罗勇刚(Yonggang Luo) wrote:
> >
> >
> > On Fri, Jan 8, 2021 at 5:54 AM Cédric Le Goater <clg@kaod.org <mailto:
clg@kaod.org>> wrote:
> >>
> >> 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> <
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  ?
> >
> >
> > Before this patch, VxWorks can working, but after this, VxWorks can not
boot anymore.
>
> I suppose you did a bisect to reach this patch.
>
> Which QEMU machine is impacted ? Which CPU ? What are the symptoms ?
>
> Did you try to run with -d exec or -d in_asm to identify the exact
> instruction ?
>
> From there, you could try to revert partially the patch above to
> fix the problem.
>
> Thanks,
>
> C.
>
>
>
QEMU 5.2.x, an e300 based machine ppc603 are impacted.
Here is my fix, narrowed down to  MSR_TGPR and  MSR_ILE
```
From 42ce41671f1e6c4dd44e6fb481bbda9df09320bd Mon Sep 17 00:00:00 2001
From: Yonggang Luo <luoyonggang@gmail.com>
Date: Sun, 10 Jan 2021 00:08:00 -0800
Subject: [PATCH] ppc: Fix rfi/rfid/hrfi/... emulation again

This revert part mask bits for ppc603/ppc4x that disabled in
 a2e71b28e832346409efc795ecd1f0a2bcb705a3.
Remove redundant macro MSR_BOOK3S_MASK.
Fixes boot VxWorks on e300

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
---
 target/ppc/excp_helper.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 1c48b9fdf6..df70c5a4e8 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -1156,8 +1156,10 @@ static inline void do_rfi(CPUPPCState *env,
target_ulong nip, target_ulong msr)
 {
     CPUState *cs = env_cpu(env);

-    /* MSR:POW cannot be set by any form of rfi */
+    /* MSR:POW,TGPR,ILE cannot be set by any form of rfi */
     msr &= ~(1ULL << MSR_POW);
+    msr &= ~(1ULL << MSR_TGPR);
+    msr &= ~(1ULL << MSR_ILE);

 #if defined(TARGET_PPC64)
     /* Switching to 32-bit ? Crop the nip */
@@ -1190,7 +1192,6 @@ void helper_rfi(CPUPPCState *env)
     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)
 {
-- 
2.29.2.windows.3

```

--
         此致
礼
罗勇刚
Yours
    sincerely,
Yonggang Luo

[-- Attachment #2: Type: text/html, Size: 13146 bytes --]