linux-kernel - Re: [PATCH 00/11] Use global pages with PTI

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Message-ID: <CA+55aFwEC1O+6qRc35XwpcuLSgJ+0GP6ciqw_1Oc-msX=efLvQ@mail.gmail.com>
Date:   Fri, 23 Mar 2018 11:26:49 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        Jürgen Groß <jgross@...e.com>,
        "the arch/x86 maintainers" <x86@...nel.org>, namit@...are.com
Subject: Re: [PATCH 00/11] Use global pages with PTI

On Fri, Mar 23, 2018 at 10:44 AM, Dave Hansen
<dave.hansen@...ux.intel.com> wrote:
>
> This adds one major change from the last version of the patch set
> (present in the last patch).  It makes all kernel text global for non-
> PCID systems.  This keeps kernel data protected always, but means that
> it will be easier to find kernel gadgets via meltdown on old systems
> without PCIDs.  This heuristic is, I think, a reasonable one and it
> keeps us from having to create any new pti=foo options

Sounds sane.

The patches look reasonable, but I hate seeing a patch series like
this where the only ostensible reason is performance, and there are no
performance numbers anywhere..

             Linus