[RFC PATCH 1/5] kasan: do not open-code addr_has_shadow

[Dmitry Vyukov]

On Fri, Feb 15, 2019 at 1:12 AM Andrew Donnellan
<andrew.donnellan at au1.ibm.com> wrote:
>
> On 15/2/19 11:04 am, Daniel Axtens wrote:
> > We have a couple of places checking for the existence of a shadow
> > mapping for an address by open-coding the inverse of the check in
> > addr_has_shadow.
> >
> > Replace the open-coded versions with the helper. This will be
> > needed in future to allow architectures to override the layout
> > of the shadow mapping.
> >
> > Signed-off-by: Daniel Axtens <dja at axtens.net>
>
> Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

Reviewed-by: Dmitry Vyukov <dvyukov at google.com>

> > ---
> >   mm/kasan/generic.c | 3 +--
> >   mm/kasan/tags.c    | 3 +--
> >   2 files changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> > index ccb6207276e3..ffc64a9a97a5 100644
> > --- a/mm/kasan/generic.c
> > +++ b/mm/kasan/generic.c
> > @@ -173,8 +173,7 @@ static __always_inline void check_memory_region_inline(unsigned long addr,
> >       if (unlikely(size == 0))
> >               return;
> >
> > -     if (unlikely((void *)addr <
> > -             kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
> > +     if (unlikely(!addr_has_shadow((void *)addr))) {
> >               kasan_report(addr, size, write, ret_ip);
> >               return;
> >       }
> > diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
> > index 0777649e07c4..bc759f8f1c67 100644
> > --- a/mm/kasan/tags.c
> > +++ b/mm/kasan/tags.c
> > @@ -109,8 +109,7 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
> >               return;
> >
> >       untagged_addr = reset_tag((const void *)addr);
> > -     if (unlikely(untagged_addr <
> > -                     kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
> > +     if (unlikely(!addr_has_shadow(untagged_addr))) {
> >               kasan_report(addr, size, write, ret_ip);
> >               return;
> >       }
> >
>
> --
> Andrew Donnellan              OzLabs, ADL Canberra
> andrew.donnellan at au1.ibm.com  IBM Australia Limited
>
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