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Date:   Tue, 16 Jun 2020 11:37:49 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Christian Brauner <christian@brauner.io>,
        Sargun Dhillon <sargun@sargun.me>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        Will Drewry <wad@chromium.org>, Shuah Khan <shuah@kernel.org>,
        Matt Denton <mpdenton@google.com>,
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        Linux Containers <containers@lists.linux-foundation.org>,
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Subject: Re: [PATCH 6/8] x86: Provide API for local kernel TLB flushing
Message-ID: <202006161136.524AA1C@keescook>
References: <20200616074934.1600036-1-keescook@chromium.org>
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 <CALCETrVSnLAkWN_b7rNY1mbF16qXavbXYtv9fVZA-Q4ZVnTXhQ@mail.gmail.com>
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On Tue, Jun 16, 2020 at 09:59:29AM -0700, Andy Lutomirski wrote:
> On Tue, Jun 16, 2020 at 12:49 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > The seccomp constant action bitmap filter evaluation routine depends
> > on being able to quickly clear the PTE "accessed" bit for a temporary
> > allocation. Provide access to the existing CPU-local kernel memory TLB
> > flushing routines.
> 
> Can you write a better justification?  Also, unless I'm just

Er, dunno? That's the entire reason this series needs it.

> incompetent this morning, I can't find anyone calling this in the
> series.

It's in patch 4, seccomp_update_bitmap():
https://lore.kernel.org/lkml/20200616074934.1600036-5-keescook@chromium.org/

-- 
Kees Cook