Re: [PATCH 1/4] x86/percpu: Use explicit segment registers in lib/cmpxchg{8,16}b_emu.S

[Uros Bizjak]

On Thu, Oct 12, 2023 at 7:54 PM Uros Bizjak <ubizjak@xxxxxxxxx> wrote:
> > This will break on !SMP builds, where per-cpu variables are just
> > regular data and not accessed with a segment prefix.
>
> Ugh, indeed. Let me rethink this a bit.

Something like this:

#ifdef CONFIG_SMP
#define PER_CPU_ARG(arg)    %__percpu_seg:arg
#define PER_CPU_VAR(var)    %__percpu_seg:(var)##__percpu_rel
#else /* ! SMP */
#define PER_CPU_ARG(arg)    arg
#define PER_CPU_VAR(var)    (var)##__percpu_rel
#endif    /* SMP */

and using the above PER_CPU_ARG in /lib/cmpxchg{8,16}b_emu.S will
solve the issue.

I will prepare a v2.

Thanks,
Uros.