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From: Mark Rutland <mark.rutland@arm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>, Will Deacon <will@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Waiman Long <longman@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH] x86/uaccess: Use pointer masking to limit uaccess speculation
Date: Wed, 2 Sep 2020 18:23:30 +0100	[thread overview]
Message-ID: <20200902172330.GB1002@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20200902133231.GA32133@lst.de>

On Wed, Sep 02, 2020 at 03:32:31PM +0200, Christoph Hellwig wrote:
> On Wed, Sep 02, 2020 at 12:43:48PM +0100, Mark Rutland wrote:
> > I'll see what I can do.
> > 
> > At first glance it looks like we might need to flesh out or refactor the
> > arm64 kernel maccess routines first (since we want the user maccess
> > routines to use LDTR/STTR instructions that can't access kernel memory),
> > but after that I think the rest is largely mechanical.
> 
> Yes, the first thing is to implement __get_kernel_nofaul and
> __put_kernel_nofault.  I think they should mostly look like the existing
> non-UAO versions of get_user and put_user with a fixed address space
> limit.

I've pushed an initial/incomplete/WIP stab (just the kernel accessors)
to:

https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/set_fs-removal

... and doing that made it clear that the necessary arm64 rework is a
bit more fractal than I thought (e.g. SDEI bits), so it might be a short
while before I post a series.

It might be handy to have a stable branch with the common bits so that
the arm64 rework could go via the arm64 tree in case there's any
fallout.

Thanks for all of this!

Mark.

  reply	other threads:[~2020-09-02 17:23 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 14:50 [PATCH] x86/uaccess: Use pointer masking to limit uaccess speculation Josh Poimboeuf
2020-08-19 16:39 ` Andy Lutomirski
2020-08-19 17:02   ` Josh Poimboeuf
2020-08-19 21:30     ` David Laight
2020-08-20  0:18     ` Andy Lutomirski
2020-08-28 19:29 ` Josh Poimboeuf
2020-08-29 13:21   ` David Laight
2020-08-29 19:31     ` David Laight
2020-08-31 17:31       ` Josh Poimboeuf
2020-09-01  8:32         ` David Laight
2020-09-01 14:26           ` Josh Poimboeuf
2020-09-01 15:00             ` David Laight
2020-09-01 15:24               ` Josh Poimboeuf
2020-09-01 14:02 ` Mark Rutland
2020-09-01 14:21   ` Josh Poimboeuf
2020-09-01 14:52     ` Mark Rutland
2020-09-01 14:46   ` Christoph Hellwig
2020-09-01 14:54     ` Mark Rutland
2020-09-01 15:05       ` Christoph Hellwig
2020-09-01 15:46         ` Christoph Hellwig
2020-09-02 11:43           ` Mark Rutland
2020-09-02 13:32             ` Christoph Hellwig
2020-09-02 17:23               ` Mark Rutland [this message]
2020-09-03  6:56                 ` Christoph Hellwig
2020-09-04 16:00                   ` Mark Rutland

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