Re: [PATCH 2/4] arm64: hide more compat_vdso code

[Arnd Bergmann]

On Mon, Oct 26, 2020 at 5:55 PM Mark Rutland <mark.rutland@xxxxxxx> wrote:
> On Mon, Oct 26, 2020 at 05:03:29PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > When CONFIG_COMPAT_VDSO is disabled, we get a warning
> > about a potential out-of-bounds access:
> >
> > arch/arm64/kernel/vdso.c: In function 'aarch32_vdso_mremap':
> > arch/arm64/kernel/vdso.c:86:37: warning: array subscript 1 is above array bounds of 'struct vdso_abi_info[1]' [-Warray-bounds]
> >    86 |  unsigned long vdso_size = vdso_info[abi].vdso_code_end -
> >       |                            ~~~~~~~~~^~~~~
> >
> > This is all in dead code however that the compiler is unable to
> > eliminate by itself.
> >
> > Change the array to individual local variables that can be
> > dropped in dead code elimination to let the compiler understand
> > this better.
> >
> > Fixes: 0cbc2659123e ("arm64: vdso32: Remove a bunch of #ifdef CONFIG_COMPAT_VDSO guards")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>
> This looks like a nice cleanup to me! I agree we don't need the array
> here.
>
> Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>

Thanks!

I see the patch now conflicts with "mm: forbid splitting special mappings"
in -mm, by Dmitry Safonov. I have rebased my patch on top, should
I send it to Andrew for inclusion in -mm then?

      Arnd