On Wed, Dec 02, 2020 at 01:52:16PM +0000, Qais Yousef wrote: > On 12/01/20 16:56, Will Deacon wrote: > > On Fri, Nov 27, 2020 at 01:12:17PM +0000, Qais Yousef wrote: > > > On 11/24/20 15:50, Will Deacon wrote: > > > > Scheduling a 32-bit application on a 64-bit-only CPU is a bad idea. > > > > > > > > Ensure that 32-bit applications always take the slow-path when returning > > > > to userspace on a system with mismatched support at EL0, so that we can > > > > avoid trying to run on a 64-bit-only CPU and force a SIGKILL instead. > > > > > > > > Signed-off-by: Will Deacon <will@xxxxxxxxxx> > > > > --- > > > > > > nit: We drop this patch at the end. Can't we avoid it altogether instead? > > > > I did it like this so that the last patch can be reverted for > > testing/debugging, but also because I think it helps the structure of the > > series. > > Cool. I had a comment about the barrier(), you were worried about > cpu_affinity_invalid() being inlined by the compiler and then things get > mangled such that TIF_NOTIFY_RESUME clearing is moved after the call as you > described? Can the compiler move things if cpu_affinity_invalid() is a proper > function call (not inlined)? I think function calls implicitly clobber memory, but you'd have to annotate the thing as noinline to prevent it being inlined. Will
