From: Pavel Machek <pavel@ucw.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Olivier Galibert <galibert@pobox.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
jikos@suse.cz
Subject: Re: Linux 4.15-rc7
Date: Fri, 12 Jan 2018 21:41:08 +0100 [thread overview]
Message-ID: <20180112204108.GB4918@amd> (raw)
In-Reply-To: <CA+55aFyDtWAOaXZuNtCFb=a1MAazxcZ02ut-RkOqGj4mcXyNYA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1336 bytes --]
On Fri 2018-01-12 11:44:48, Linus Torvalds wrote:
> On Fri, Jan 12, 2018 at 11:38 AM, Pavel Machek <pavel@ucw.cz> wrote:
> >
> > I'll try to do the right thing. OTOH... I don't like the fact that
> > kernel memory on my machine is currently readable, probably even from
> > javascript.
>
> Oh, absolutely. I'm just saying that it's probably best to try to
> start from the x86-64 KPTI model, and see how that works for x86-32.
>
> Maybe some of the 4G:4G entry code could come in handy as a "these are
> the issues" kind of thing.
Ok, so I do have the diff that compiles, and it is 300 lines. Those
will be extremely tricky 300 lines, but...
> > I tried disabling CPU caches. Just like that, off, boom. My system
> > will not survive that, and it looks like 100x slowdown.
>
> Yeah, no. That is not a realistic thing to do on any hardware since
> the PPro, I'm afraid.
What is special about PPro?
Well -- cache off kind of is what I want -- kills Spectre _and_
Meltdown ;-), attacking close to the fundametal issue. And it really
should be doable on UP system, right?
I guess I should re-try with plain VGA console, not framebuffer.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]
next prev parent reply other threads:[~2018-01-12 20:41 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-07 22:55 Linux 4.15-rc7 Linus Torvalds
2018-01-08 7:20 ` Thomas Gleixner
2018-01-10 23:32 ` Pavel Machek
2018-01-11 11:29 ` Olivier Galibert
2018-01-11 14:06 ` Nikolay Borisov
2018-01-12 11:06 ` Pavel Machek
2018-01-12 13:23 ` Arnd Bergmann
2018-01-12 14:43 ` Pavel Machek
2018-01-12 17:20 ` vcaputo
2018-01-12 20:11 ` Arnd Bergmann
2018-01-12 22:04 ` vcaputo
2018-01-12 22:08 ` Arnd Bergmann
2018-01-12 22:58 ` vcaputo
2018-01-12 17:34 ` Linus Torvalds
2018-01-12 19:38 ` Pavel Machek
2018-01-12 19:44 ` Linus Torvalds
2018-01-12 20:41 ` Pavel Machek [this message]
2018-01-13 12:52 ` kernel page table isolation for x86-32 was " Pavel Machek
2018-01-11 14:07 ` Jiri Kosina
2018-01-19 10:28 ` Pavel Machek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180112204108.GB4918@amd \
--to=pavel@ucw.cz \
--cc=arnd@arndb.de \
--cc=galibert@pobox.com \
--cc=jikos@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).