[PATCH v6 02/21] arm64: Allow mismatched 32-bit EL0 support

[Will Deacon]

On Fri, May 21, 2021 at 04:22:55PM +0100, Qais Yousef wrote:
> On 05/18/21 10:47, Will Deacon wrote:
> > When confronted with a mixture of CPUs, some of which support 32-bit
> > applications and others which don't, we quite sensibly treat the system
> > as 64-bit only for userspace and prevent execve() of 32-bit binaries.
> > 
> > Unfortunately, some crazy folks have decided to build systems like this
> > with the intention of running 32-bit applications, so relax our
> > sanitisation logic to continue to advertise 32-bit support to userspace
> > on these systems and track the real 32-bit capable cores in a cpumask
> > instead. For now, the default behaviour remains but will be tied to
> > a command-line option in a later patch.
> > 
> > Signed-off-by: Will Deacon <will at kernel.org>
> > ---
> >  arch/arm64/include/asm/cpucaps.h    |   3 +-
> 
> Heads up. I just tried to apply this on 5.13-rc2 and it failed because cpucaps.
> was removed; it's autogenerated now.
> 
> See commit 0c6c2d3615ef: ()"arm64: Generate cpucaps.h")

Yup, cheers. I'll sort that out once we're at the stage where we're merging
patches.

Will