Re: [PATCH 1/3] arm/arm64/xen: use C inlines for privcmd_call

Pavel Tatashin
2019-11-22T00:30:55Z

> > +#ifdef CONFIG_CPU_SW_DOMAIN_PAN
> > +static __always_inline void uaccess_enable(void)
> > +{
> > + unsigned long val = DACR_UACCESS_ENABLE;
> > +
> > + asm volatile("mcr p15, 0, %0, c3, c0, 0" : : "r" (val));
> > + isb();
> > +}
> > +
> > +static __always_inline void uaccess_disable(void)
> > +{
> > + unsigned long val = DACR_UACCESS_ENABLE;

Oops, should be DACR_UACCESS_DISABLE.

> > +
> > + asm volatile("mcr p15, 0, %0, c3, c0, 0" : : "r" (val));
> > + isb();
> > +}
>
> Rather than inventing these, why not use uaccess_save_and_enable()..
> uaccess_restore() around the Xen call?

Thank you for suggestion: uaccess_enable() and uaccess_disable() are
common calls with arm64, so I will need them, but I think I can use
set_domain() with DACR_UACCESS_DISABLE /DACR_UACCESS_ENABLE inside
these inlines.

Pasha