From: Guenter Roeck <linux@roeck-us.net>
To: Joerg Roedel <jroedel@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Michal Hocko <mhocko@suse.com>, Andi Kleen <ak@linux.intel.com>,
the arch/x86 maintainers <x86@kernel.org>,
Dave Hansen <dave.hansen@intel.com>, Pavel Machek <pavel@ucw.cz>
Subject: Re: efi boot failures due to PTI with 32 bit builds and Intel CPUs
Date: Thu, 30 Aug 2018 12:24:24 -0700 [thread overview]
Message-ID: <20180830192424.GC6752@roeck-us.net> (raw)
In-Reply-To: <20180830184639.6iv5itjex6y45w3j@suse.de>
On Thu, Aug 30, 2018 at 08:46:39PM +0200, Joerg Roedel wrote:
> On Thu, Aug 30, 2018 at 11:21:49AM -0700, Linus Torvalds wrote:
> > On Thu, Aug 30, 2018 at 11:08 AM Joerg Roedel <jroedel@suse.de> wrote:
> > >
> > > Without a mapped GDT the #PF and #DF handlers also can't be started, so
> > > the machine triple-faults. Below diff fixes it for me, I'll send a
> > > proper patch tomorrow.
> >
> > Hmm. Is there any reason why this code doesn't just use
> >
> > load_fixmap_gdt(0);
>
> No idea, probably the function didn't exist when the code was written?
> I can change that when writing the patch.
>
> > and shouldn't it do it after loading the new %cr3?
>
> That seems more robust, yes. No sure if the old %cr3
> (initial_page_table) has the fixmap gdt mapped at all.
All three variants (hardcoded, call load_fixmap_gdt(0) first, call
load_fixmap_gdt(0) after load_cr3()) work for me. Feel free to add
Tested-by: Guenter Roeck <linux@roeck-us.net>
when you submit the patch.
Thanks a lot for tracking this down!
Guenter
prev parent reply other threads:[~2018-08-30 19:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 20:16 efi boot failures due to PTI with 32 bit builds and Intel CPUs Guenter Roeck
2018-08-29 20:28 ` Dave Hansen
2018-08-29 21:12 ` Guenter Roeck
2018-08-30 7:19 ` Joerg Roedel
2018-08-30 10:11 ` Guenter Roeck
2018-08-30 11:30 ` Joerg Roedel
2018-08-30 12:20 ` Guenter Roeck
2018-08-30 18:08 ` Joerg Roedel
2018-08-30 18:21 ` Linus Torvalds
2018-08-30 18:46 ` Joerg Roedel
2018-08-30 19:24 ` Guenter Roeck [this message]
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