Re: [PATCH 1/8] kasan,x86: Frob kasan_report() in an exception

[Peter Zijlstra]

On Wed, Mar 06, 2019 at 02:13:47PM +0100, Peter Zijlstra wrote:
> +static __always_inline unsigned long smap_save(void)
> +{
> +	unsigned long flags = arch_local_save_flags();
> +	clac();
> +	return flags;
> +}
> +
> +static __always_inline void smap_restore(unsigned long flags)
> +{
> +	arch_local_irq_restore(flags);
> +}

ARGH; the bloody paravirt me harder nonsense makes that pvops calls.

And that (obviously) explodes.. Anybody got any clue why that Xen
trainwreck wants to paravirt: "PUSHF;POP" and "PUSH;POPF" !?

Also; I suppose I can ALTERNATIVE the whole thing, because Xen will not
be having SMAP in the first place I suppose.