linux-kernel - Re: [kernel-hardening] [PATCH v5 04/10] arm64: Add __flush_tlb

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Message-ID: <20170814170125.ledrnrik3km66y33@smitten>
Date:   Mon, 14 Aug 2017 11:01:25 -0600
From:   Tycho Andersen <tycho@...ker.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-hardening@...ts.openwall.com,
        Marco Benatto <marco.antonio.780@...il.com>,
        Juerg Haefliger <juerg.haefliger@...onical.com>,
        Juerg Haefliger <juerg.haefliger@....com>
Subject: Re: [kernel-hardening] [PATCH v5 04/10] arm64: Add __flush_tlb_one()

On Mon, Aug 14, 2017 at 05:50:47PM +0100, Mark Rutland wrote:
> On Mon, Aug 14, 2017 at 10:35:36AM -0600, Tycho Andersen wrote:
> > Hi Mark,
> > 
> > On Sat, Aug 12, 2017 at 12:26:03PM +0100, Mark Rutland wrote:
> > > On Wed, Aug 09, 2017 at 02:07:49PM -0600, Tycho Andersen wrote:
> > > > +static inline void __flush_tlb_one(unsigned long addr)
> > > > +{
> > > > +	dsb(ishst);
> > > > +	__tlbi(vaae1is, addr >> 12);
> > > > +	dsb(ish);
> > > > +	isb();
> > > > +}
> > > 
> > > Is this going to be called by generic code?
> > 
> > Yes, it's called in mm/xpfo.c:xpfo_kunmap.
> > 
> > > It would be nice if we could drop 'kernel' into the name, to make it clear this
> > > is intended to affect the kernel mappings, which have different maintenance
> > > requirements to user mappings.
> 
> > It's named __flush_tlb_one after the x86 (and a few other arches)
> > function of the same name. I can change it to flush_tlb_kernel_page,
> > but then we'll need some x86-specific code to map the name as well.
> > 
> > Maybe since it's called from generic code that's warranted though?
> > I'll change the implementation for now, let me know what you want to
> > do about the name.
> 
> I think it would be preferable to do so, to align with 
> flush_tlb_kernel_range(), which is an existing generic interface.
> 
> That said, is there any reason not to use flush_tlb_kernel_range()
> directly?

I don't think so, I'll change the generic code to that and drop this
patch.

Thanks!

Tycho