From: Andy Lutomirski <luto@kernel.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andrew Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Baoquan He <bhe@redhat.com>,
Matthew Wilcox <willy@infradead.org>, X86 ML <x86@kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv3 1/3] x86/mm: Move LDT remap out of KASLR region on 5-level paging
Date: Fri, 2 Nov 2018 14:07:44 -0700 [thread overview]
Message-ID: <CALCETrXMA=4694sstXYWK1rSiHBAFbN=kPpB5PcG2uBpyxoF3g@mail.gmail.com> (raw)
In-Reply-To: <20181026122856.66224-2-kirill.shutemov@linux.intel.com>
On Fri, Oct 26, 2018 at 5:29 AM Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> On 5-level paging LDT remap area is placed in the middle of
> KASLR randomization region and it can overlap with direct mapping,
> vmalloc or vmap area.
>
> Let's move LDT just before direct mapping which makes it safe for KASLR.
> This also allows us to unify layout between 4- and 5-level paging.
>
> We don't touch 4 pgd slot gap just before the direct mapping reserved
> for a hypervisor, but move direct mapping by one slot instead.
>
> The LDT mapping is per-mm, so we cannot move it into P4D page table next
> to CPU_ENTRY_AREA without complicating PGD table allocation for 5-level
> paging.
Reviewed-by: Andy Lutomirski <luto@kernel.org>
(assuming it passes tests with 4-level and 5-level. my test setup is
current busted, and i'm bisecting it.)
next prev parent reply other threads:[~2018-11-02 21:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-26 12:28 [PATCHv3 0/3] Fix couple of issues with LDT remap for PTI Kirill A. Shutemov
2018-10-26 12:28 ` [PATCHv3 1/3] x86/mm: Move LDT remap out of KASLR region on 5-level paging Kirill A. Shutemov
2018-11-02 21:07 ` Andy Lutomirski [this message]
2018-11-06 20:39 ` [tip:x86/urgent] " tip-bot for Kirill A. Shutemov
2018-11-10 12:29 ` [PATCHv3 1/3] " Baoquan He
2018-11-23 15:58 ` Kirill A. Shutemov
2018-12-03 3:01 ` Baoquan He
2018-12-03 9:26 ` Kirill A. Shutemov
2018-10-26 12:28 ` [PATCHv3 2/3] x86/ldt: Unmap PTEs for the slot before freeing LDT pages Kirill A. Shutemov
2018-10-31 12:17 ` Kirill A. Shutemov
2018-11-06 20:40 ` [tip:x86/urgent] " tip-bot for Kirill A. Shutemov
2018-10-26 12:28 ` [PATCHv3 3/3] x86/ldt: Remove unused variable in map_ldt_struct() Kirill A. Shutemov
2018-11-02 21:08 ` Andy Lutomirski
2018-11-06 20:40 ` [tip:x86/urgent] " tip-bot for Kirill A. Shutemov
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