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Re: What's the correct way to implement rfi and related instruction.
From: |
Cédric Le Goater |
Subject: |
Re: What's the correct way to implement rfi and related instruction. |
Date: |
Fri, 8 Jan 2021 11:02:29 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 |
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.