linux-kernel - Re: "bad pmd" errors + oops with KPTI on 4.14.11 after loading X.509 certs

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Message-ID: <alpine.DEB.2.20.1801041733170.1771@nanos>
Date:   Thu, 4 Jan 2018 17:34:09 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andy Lutomirski <luto@...nel.org>
cc:     Benjamin Gilbert <benjamin.gilbert@...eos.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        linux-mm@...ck.org, stable <stable@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Garnier <thgarnie@...gle.com>,
        Alexander Kuleshov <kuleshovmail@...il.com>
Subject: Re: "bad pmd" errors + oops with KPTI on 4.14.11 after loading X.509
 certs

On Thu, 4 Jan 2018, Andy Lutomirski wrote:
> On Thu, Jan 4, 2018 at 4:28 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > --- a/arch/x86/include/asm/pgtable_64_types.h
> > +++ b/arch/x86/include/asm/pgtable_64_types.h
> > @@ -88,7 +88,7 @@ typedef struct { pteval_t pte; } pte_t;
> >  # define VMALLOC_SIZE_TB       _AC(32, UL)
> >  # define __VMALLOC_BASE                _AC(0xffffc90000000000, UL)
> >  # define __VMEMMAP_BASE                _AC(0xffffea0000000000, UL)
> > -# define LDT_PGD_ENTRY         _AC(-4, UL)
> > +# define LDT_PGD_ENTRY         _AC(-3, UL)
> >  # define LDT_BASE_ADDR         (LDT_PGD_ENTRY << PGDIR_SHIFT)
> >  #endif
> 
> If you actually change the memory map order, you need to change the
> shadow copy in mm/dump_pagetables.c, too.  I have a draft patch to
> just sort the damn list, but that's not ready yet.

Yes, I forgot that in the first attempt. Noticed myself when dumping it,
but that should be irrelevant to figure out whether it fixes the problem at
hand.