Re: [PATCH v2 08/19] target/ppc: Sign-extend large decrementer to 64-bits

[Nicholas Piggin]

On Fri Sep 1, 2023 at 10:25 PM AEST, Cédric Le Goater wrote:
> Nick,
>
> On 8/8/23 06:19, Nicholas Piggin wrote:
> > When storing a large decrementer value with the most significant
> > implemented bit set, it is to be treated as a negative and sign
> > extended.
> > 
> > This isn't hit for book3s DEC because of another bug, fixing it
> > in the next patch exposes this one and can cause additional
> > problems, so fix this first. It can be hit with HDECR and other
> > edge triggered types.
> > 
> > Fixes: a8dafa52518 ("target/ppc: Implement large decrementer support for 
> > TCG")
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
> >   hw/ppc/ppc.c | 8 ++++++--
> >   1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> > index a397820d9c..fb4784793c 100644
> > --- a/hw/ppc/ppc.c
> > +++ b/hw/ppc/ppc.c
> > @@ -743,7 +743,9 @@ target_ulong cpu_ppc_load_decr(CPUPPCState *env)
> >        * to 64 bits, otherwise it is a 32 bit value.
> >        */
> >       if (env->spr[SPR_LPCR] & LPCR_LD) {
> > -        return decr;
> > +        PowerPCCPU *cpu = env_archcpu(env);
> > +        PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> > +        return sextract64(decr, 0, pcc->lrg_decr_bits);
> >       }
> >       return (uint32_t) decr;
> >   }
> > @@ -762,7 +764,9 @@ target_ulong cpu_ppc_load_hdecr(CPUPPCState *env)
> >        * extended to 64 bits, otherwise it is 32 bits.
> >        */
> >       if (pcc->lrg_decr_bits > 32) {
> > -        return hdecr;
> > +        PowerPCCPU *cpu = env_archcpu(env);
> > +        PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
>
> Why are 'cpu' and 'ppc' duplicated ?

Hmm.. cut and paste bug maybe, good catch.

I'll send an increment to tidy it if needed.

Thanks,
Nick