linux-kernel - Re: [tip:x86/mm] x86/boot/compressed/64: Describe the logic behind the LA57 check

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: <20180312143212.77z2ptyqbsbqdll3@gmail.com>
Date:   Mon, 12 Mar 2018 15:32:12 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        kirill.shutemov@...ux.intel.com, gorcunov@...nvz.org,
        luto@...capital.net, keescook@...omium.org, willy@...radead.org,
        torvalds@...ux-foundation.org, tglx@...utronix.de, bp@...e.de,
        andy.shevchenko@...il.com, linux-kernel@...r.kernel.org,
        hpa@...or.com, ebiederm@...ssion.com, jgross@...e.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/mm] x86/boot/compressed/64: Describe the logic behind
 the LA57 check


* Kirill A. Shutemov <kirill@...temov.name> wrote:

> > We can of course bike shed / benchmark this once my desktop refresh
> > sports this feature, but ISTR this being one of the very first things
> > Ingo mentioned when we started this whole 5L thing.
> 
> I would rather not fix the problem that may not actually exist. :)

That 5 level pagetables involve more overhead is a realy problem.

By default we should only enable 5-level paging if memory mappings exist in
the memory map that require the extended physical memory space.

Thanks,

	Ingo