linux-kernel - Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace page tables

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Message-ID: <CALCETrWBcEp+5iFPqP=V740CmZOBQ9P_+9h57G9tEUiJfvnLJw@mail.gmail.com>
Date:   Thu, 2 Nov 2017 00:54:36 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>, Kees Cook <keescook@...gle.com>,
        Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace
 page tables

On Thu, Nov 2, 2017 at 12:32 AM, Andy Lutomirski <luto@...nel.org> wrote:
> On Wed, Nov 1, 2017 at 1:33 PM, Andy Lutomirski <luto@...nel.org> wrote:
>> On Wed, Nov 1, 2017 at 12:05 PM, Linus Torvalds
>> <torvalds@...ux-foundation.org> wrote:
>>> On Wed, Nov 1, 2017 at 11:46 AM, Dave Hansen
>>> <dave.hansen@...ux.intel.com> wrote:
>>>>
>>>> The vmalloc()'d stacks definitely need the page table walk.
>>>
>>> Ugh, yes. Nasty.
>>>
>>> Andy at some point mentioned a per-cpu initial stack trampoline thing
>>> for his exception patches, but I'm not sure he actually ever did that.
>>>
>>> Andy?
>>
>> I'm going to push it to kernel.org very shortly (like twenty minutes
>> maybe).  Then the 0day bot can chew on it.  With the proposed LDT
>> rework, we don't need to do any of dynamic mapping stuff, I think.
>
> FWIW, I pushed all but the actual stack switching part.  Something
> broke in the rebase and it doesn't boot right now :(

Okay, that was embarrassing.  The rebase error was, drumroll please, I
forgot one of the patches.  Sigh.

It's here:

https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/log/?h=x86/entry_consolidation

The last few patches are terminally ugly.  I'll clean them up shortly
and email them out.  That being said, unless there's a showstopper
bug, this should be a fine base for Dave's development.