From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f197.google.com (mail-ot0-f197.google.com [74.125.82.197]) by kanga.kvack.org (Postfix) with ESMTP id C114D6B0273 for ; Tue, 28 Nov 2017 00:03:34 -0500 (EST) Received: by mail-ot0-f197.google.com with SMTP id v15so16888220ote.10 for ; Mon, 27 Nov 2017 21:03:34 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id x137si11263744oia.291.2017.11.27.21.03.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Nov 2017 21:03:33 -0800 (PST) Date: Mon, 27 Nov 2017 23:03:22 -0600 From: Josh Poimboeuf Subject: Re: [PATCH 2/5] x86/mm/kaiser: Add a banner Message-ID: <20171128050322.f2mgrapew3illscm@treble> References: <20171127223110.479550152@infradead.org> <20171127223405.231444600@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Peter Zijlstra , "linux-kernel@vger.kernel.org" , Dave Hansen , Ingo Molnar , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Linus Torvalds , Rik van Riel , Daniel Gruss , Hugh Dickins , Kees Cook , "linux-mm@kvack.org" , michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at On Mon, Nov 27, 2017 at 07:36:40PM -0800, Andy Lutomirski wrote: > On Mon, Nov 27, 2017 at 2:31 PM, Peter Zijlstra wrote: > > So we can more easily see if the shiny got enabled. > > > > Signed-off-by: Peter Zijlstra (Intel) > > --- > > arch/x86/mm/kaiser.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > --- a/arch/x86/mm/kaiser.c > > +++ b/arch/x86/mm/kaiser.c > > @@ -425,6 +425,8 @@ void __init kaiser_init(void) > > if (!kaiser_enabled) > > return; > > > > + printk("All your KAISER are belong to us\n"); > > + > > All your incomprehensible academic names are belong to us. > > On a serious note, can we please banish the name KAISER from all the > user-facing bits? No one should be setting a boot option that has a > name based on an academic project called "Kernel Address Isolation to > have Side-channels Efficiently Removed". We're not efficiently > removing side channels. The side channels are still very much there. > Heck, the series as currently presented doesn't even rescue kASLR. It > could*, if we were to finish the work that I mostly started and > completely banish all the normal kernel mappings from the shadow** > tables. We're rather inefficiently (and partially!) mitigating the > fact that certain CPU designers have had their heads up their > collective arses for *years* and have failed to pay attention to > numerous academic papers documenting that fact. > > Let's call the user facing bits "separate user pagetables". If we > want to make it conditioned on a future cpu cap called > X86_BUG_REALLY_DUMB_SIDE_CHANNELS, great, assuming a better CPU ever > shows up. But please let's not make users look up WTF "KAISER" means. > > * No one ever documented the %*!& side channels AFAIK, so everything > we're talking about here is mostly speculation. > > ** The word "shadow" needs to die, too. I know what shadow page > tables are, and they have *nothing* to do with KAISER. +1. Somebody please rename KAISER and shadow page tables for more clarity. To fix KASLR I think we need to move (at least parts of) .entry.text, .irqentry.text, and .entry_trampoline into their own fixed section(s). Is there anything else missing? -- Josh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org