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Re: [PATCH 17/19] target/arm: add ARMv8.4-SEL2 extension


From: Rémi Denis-Courmont
Subject: Re: [PATCH 17/19] target/arm: add ARMv8.4-SEL2 extension
Date: Wed, 13 Jan 2021 15:12:04 +0200

Le tiistaina 12. tammikuuta 2021, 23.30.39 EET Richard Henderson a écrit :
> On 1/12/21 12:45 AM, remi.denis.courmont@huawei.com wrote:
> > From: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
> > 
> > This adds handling for the SCR_EL3.EEL2 bit.
> > 
> > Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
> 
> The patch title seems to have gone awry.
> 
> > @@ -2832,9 +2832,19 @@ static bool msr_banked_access_decode
> > 
> >          }
> >          if (s->current_el == 1) {
> >          
> >              /* If we're in Secure EL1 (which implies that EL3 is AArch64)
> > 
> > -             * then accesses to Mon registers trap to EL3
> > +             * then accesses to Mon registers trap to Secure EL2, if it
> > exists, +             * otherwise EL3.
> > 
> >               */
> > 
> > -            TCGv_i32 tcg_el = tcg_const_i32(3);
> > +            TCGv_i32 tcg_el;
> > +
> > +            if (dc_isar_feature(aa64_sel2, s)) {
> > +                /* Target EL is EL<3 minus SCR_EL3.EEL2> */
> > +                tcg_el = load_cpu_field(cp15.scr_el3);
> > +                tcg_gen_sextract_i32(tcg_el, tcg_el, ctz32(SCR_EEL2), 1);
> > +                tcg_gen_addi_i32(tcg_el, tcg_el, 3);
> > +            } else {
> > +                tcg_el = tcg_const_i32(3);
> > +            }
> 
> You can't test an aa64 feature without verifying that the cpu has aa64
> support (if the cpu is strictly aa32, the aa64 registers are
> undefined/uninitialized).  So:
> 
>     if (arm_dc_feature(s, ARM_FEATURE_AARCH64) &&
>         dc_isar_feature(aa64_sel2, s)) {
>         ...
> 

Hmm, yeah. Should this be an ifdef on TARGET_AARCH64 instead?

Also do we need to revector the exception code, or leave it mostly duplicated 
as is?


> With those things changed,
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> 
> 
> r~


-- 
Rémi Denis-Courmont





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