From: geert@linux-m68k.org (Geert Uytterhoeven)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] arm64: mm: Export __sync_icache_dcache() for xen-privcmd
Date: Mon, 30 Jul 2018 08:46:21 +0200 [thread overview]
Message-ID: <CAMuHMdVZHiqi9Wex05v6fLcndfN7oDuJK3ft7O=itEM4DwfP2w@mail.gmail.com> (raw)
In-Reply-To: <20180727132243.GA28549@arm.com>
On Fri, Jul 27, 2018 at 3:23 PM Will Deacon <will.deacon@arm.com> wrote:
> 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.
Note that this is a build regression in v4.18-rc4 and later:
http://kisskb.ellerman.id.au/kisskb/buildresult/13450058/
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2018-07-30 6:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 23:18 [RFC PATCH] arm64: mm: Export __sync_icache_dcache() for xen-privcmd Ben Hutchings
2018-07-27 12:06 ` Catalin Marinas
2018-07-27 13:22 ` Will Deacon
2018-07-30 6:46 ` Geert Uytterhoeven [this message]
2018-07-30 6:50 ` Geert Uytterhoeven
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