linux-kernel - Re: [PATCH 00/35 v5] PTI support for x32

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Message-ID: <20180416160154.GE15462@8bytes.org>
Date:   Mon, 16 Apr 2018 18:01:54 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.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>,
        "Liguori, Anthony" <aliguori@...zon.com>,
        Daniel Gruss <daniel.gruss@...k.tugraz.at>,
        Hugh Dickins <hughd@...gle.com>,
        Kees Cook <keescook@...gle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <llong@...hat.com>, Pavel Machek <pavel@....cz>,
        "David H . Gutteridge" <dhgutteridge@...patico.ca>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 00/35 v5] PTI support for x32

Hi Linus,

On Mon, Apr 16, 2018 at 08:32:46AM -0700, Linus Torvalds wrote:
> Also, it would be nice to have performance numbers,

Here are some numbers I gathered for Ingo on v2 of the patch-set:

	https://marc.info/?l=linux-kernel&m=151844711432661&w=2

I don't think they significantly changed, but I can measure them again
if needed.

Besides those, what other numbers/tests are you interested in?

> and check that the global page issues are at least fixed on 32-bit
> too, since we screwed that up on x86-64 initially.
> 
> On x86-32, the global pages are likely a bigger deal since there's no PCID.

Okay, I verify if there are any global bits left in the page-tables.
According to the PTDUMP_X86 the cpu_entry_area is mapped with G=1 (which
should be fine?) and another 4M range in the kernel mapping. I need to
check what that is.

Thanks,

	Joerg


> 
>                   Linus