[RFC PATCH] arm64: mm: Export __sync_icache_dcache() for xen-privcmd

[will.deacon@arm.com (Will Deacon)]

On Fri, Jul 27, 2018 at 01:06:33PM +0100, Catalin Marinas wrote:
> On Thu, Jul 12, 2018 at 12:18:22AM +0100, Ben Hutchings wrote:
> > The xen-privcmd driver, which can be modular, calls set_pte_at()
> > which in turn may call __sync_icache_dcache().
> > 
> > The call to __sync_icache_dcache() may be optimised out because it is
> > conditional on !pte_special(), and xen-privcmd calls pte_mkspecial().
> > But it seems unwise to rely on this optimisation.
> > 
> > Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE")
> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > ---
> > This is an RFC since I haven't found an actual build failure.  Using
> > Debian's gcc 7.3 with either CC_OPTIMIZE_FOR_PERFORMANCE or
> > CC_OPTIMIZE_FOR_SIZE, the call *is* optimised away.
> 
> Since apply_to_page_range() is EXPORT_SYMBOL_GPL() and a
> pte_fn_t function would likely use set_pte_at(), I'm fine with this
> patch for consistency.
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Okey doke, I'll pick this up for 4.19.

Will