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

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Message-ID: <2607b1b1-89a7-635c-0c5d-da9f558241f4@linux.intel.com>
Date:   Sat, 31 Mar 2018 11:19:48 -0700
From:   Dave Hansen <dave.hansen@...ux.intel.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        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 03/30/2018 10:39 PM, Ingo Molnar wrote:
> There were a couple of valid review comments which need to be addressed as well, 
> but other than that it all looks good to me and I plan to apply the next 
> iteration.

Testing on that non-PCID systems showed an oddity with parts of the
kernel image that are modified later in boot (when we set the kernel
image read-only).  We split a few of the PMD entries and the the old
(early boot) values were being used for userspace.

I don't think this is a big deal.  The most annoying thing is that it
makes it harder to quickly validate that all of the things we set to
global *should* be global.  I'll put some examples of how this looks in
the patch when I repost.