linux-kernel - Re: [PATCH 03/39] x86/entry/32: Load task stack from x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180713094849.5bsfpwhxzo5r5exk@8bytes.org>
Date:   Fri, 13 Jul 2018 11:48:49 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Brian Gerst <brgerst@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Eduardo Valentin <eduval@...zon.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Will Deacon <will.deacon@....com>, aliguori@...zon.com,
        daniel.gruss@...k.tugraz.at, hughd@...gle.com, keescook@...gle.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <llong@...hat.com>, Pavel Machek <pavel@....cz>,
        "David H . Gutteridge" <dhgutteridge@...patico.ca>, jroedel@...e.de
Subject: Re: [PATCH 03/39] x86/entry/32: Load task stack from x86_tss.sp1 in
 SYSENTER handler

On Thu, Jul 12, 2018 at 01:49:13PM -0700, Andy Lutomirski wrote:
> > On Jul 11, 2018, at 4:29 AM, Joerg Roedel <joro@...tes.org> wrote:
> >    /* Offset from the sysenter stack to tss.sp0 */
> > -    DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) -
> > +    DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp1) -
> >           offsetofend(struct cpu_entry_area, entry_stack_page.stack));
> > 
> 
> The code reads differently. Did you perhaps mean TSS_task_stack?

Well, the offset name came from TSS_sysenter_sp0, which was the offset
from the sysenter_sp0 (==sysenter-stack) to the task stack in TSS, now
sysenter_sp0 became entry_stack, because its used for all entry points
and not only sysenter. So with the old convention the naming makes still
sense, no?

> Also, the “top of task stack” is a bit weird on 32-bit due to vm86.
> Can you document *exactly* what goes in sp1?

Will do, thanks for your feedback!


	Joerg