Re: [PATCH v4 1/2] target/arm: allow DC CVA[D]P in user mode emulation

[Zhuojia Shen]

On 06/02/2023 12:27 PM +0200, Philippe Mathieu-Daudé wrote:
> On 2/6/23 00:11, Zhuojia Shen wrote:
> > DC CVAP and DC CVADP instructions can be executed in EL0 on Linux,
> > either directly when SCTLR_EL1.UCI == 1 or emulated by the kernel (see
> > user_cache_maint_handler() in arch/arm64/kernel/traps.c).
> > 
> > This patch enables execution of the two instructions in user mode
> > emulation.
> > 
> > Signed-off-by: Zhuojia Shen <chaosdefinition@hotmail.com>
> > Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> >   target/arm/helper.c | 6 ++----
> >   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> 
> > -#ifndef CONFIG_USER_ONLY
> >   static void dccvap_writefn(CPUARMState *env, const ARMCPRegInfo *opaque,
> >                             uint64_t value)
> >   {
> > @@ -7420,6 +7419,7 @@ static void dccvap_writefn(CPUARMState *env, const 
> > ARMCPRegInfo *opaque,
> >       /* This won't be crossing page boundaries */
> >       haddr = probe_read(env, vaddr, dline_size, mem_idx, GETPC());
> >       if (haddr) {
> > +#ifndef CONFIG_USER_ONLY
> 
> This ifdef'ry placement is odd. Is it to silent a
> unused-but-set-variable warning?

Yes, exactly.  Since we pass -Werror, ifdef'ing out the if statement
wouldn't even compile.

> 
> >           ram_addr_t offset;
> >           MemoryRegion *mr;
> > @@ -7430,6 +7430,7 @@ static void dccvap_writefn(CPUARMState *env, const 
> > ARMCPRegInfo *opaque,
> >           if (mr) {
> >               memory_region_writeback(mr, offset, dline_size);
> >           }
> > +#endif /*CONFIG_USER_ONLY*/
> >       }
> >   }
> > @@ -7448,7 +7449,6 @@ static const ARMCPRegInfo dcpodp_reg[] = {
> >         .fgt = FGT_DCCVADP,
> >         .accessfn = aa64_cacheop_poc_access, .writefn = dccvap_writefn },
> >   };
> > -#endif /*CONFIG_USER_ONLY*/
>