linux-kernel - Re: [GIT PULL] x86/mm changes for v4.21

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Message-ID: <20190207140131.GB32477@hirez.programming.kicks-ass.net>
Date:   Thu, 7 Feb 2019 15:01:31 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>, Ingo Molnar <mingo@...nel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rik van Riel <riel@...riel.com>
Subject: Re: [GIT PULL] x86/mm changes for v4.21

On Thu, Feb 07, 2019 at 11:50:52AM +0000, Linus Torvalds wrote:
> If you re-generate the canonical address in __cpa_addr(), now we'll
> actually have the real virtual address around for a lot of code-paths
> (pte lookup etc), which was what people wanted to avoid in the first
> place.

Note that it's an 'unsigned long' address, not an actual pointer, and
(afaict) non of the code paths use it as a pointer. This _should_ avoid
the CPU from following said pointer and doing a deref on it.

But yes, I didn't go all the way down, maybe I missed some.