[PATCH v2 05/16] arm64: Remove uaccess toggle from __flush_cache_range macro

[Fuad Tabba]

On Tue, May 18, 2021 at 5:00 PM Mark Rutland <mark.rutland at arm.com> wrote:
>
> On Mon, May 17, 2021 at 08:51:13AM +0100, Fuad Tabba wrote:
> > The uaccess toggle isn't part of the cache maintenance operation.
> > Move it directly to where it's needed.
> >
> > No functional change intended.
> >
> > Signed-off-by: Fuad Tabba <tabba at google.com>
> > ---
> >  arch/arm64/mm/cache.S | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
> > index 6babaaf34f17..d74b20cd6449 100644
> > --- a/arch/arm64/mm/cache.S
> > +++ b/arch/arm64/mm/cache.S
> > @@ -26,9 +26,6 @@
> >   *   - needs_uaccess - (macro parameter) might access user space memory
> >   */
> >  .macro       __flush_cache_range, needs_uaccess
> > -     .if     \needs_uaccess
> > -     uaccess_ttbr0_enable x2, x3, x4
> > -     .endif
> >  alternative_if ARM64_HAS_CACHE_IDC
> >       dsb     ishst
> >       b       7f
> > @@ -55,9 +52,6 @@ alternative_else_nop_endif
> >       invalidate_icache_by_line x0, x1, x2, x3, \needs_uaccess, 9f
> >  8:   mov     x0, #0
> >  1:
> > -     .if     \needs_uaccess
> > -     uaccess_ttbr0_disable x1, x2
> > -     .endif
> >       ret
> >
> >       .if     \needs_uaccess
> > @@ -92,7 +86,9 @@ SYM_FUNC_END(__flush_icache_range)
> >   *   - end     - virtual end address of region
> >   */
> >  SYM_FUNC_START(__flush_cache_user_range)
> > +     uaccess_ttbr0_enable x2, x3, x4
> >       __flush_cache_range needs_uaccess=1
> > +     uaccess_ttbr0_disable x1, x2
> >  SYM_FUNC_END(__flush_cache_user_range)
>
> The RET is still in the __flush_cache_range macro, so I don't think
> we'll ever execute the uaccess_ttbr0_disable step here.

Yes. Like you suggested earlier, it's moving out of the macro.

Thanks,
/fuad

> Mark.
>
> >
> >  /*
> > --
> > 2.31.1.751.gd2f1c929bd-goog
> >