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From: Christoph Hellwig <hch@lst.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Christoph Hellwig <hch@lst.de>,
	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: Tue, 1 Sep 2020 17:46:29 +0200	[thread overview]
Message-ID: <20200901154629.GA882@lst.de> (raw)
In-Reply-To: <20200901150553.GA30034@lst.de>

On Tue, Sep 01, 2020 at 05:05:53PM +0200, Christoph Hellwig wrote:
> > Is there anything in particular that's tricky, or do you just want
> > someone to look generally? From a quick grep arch/arm64/* looks clean, but
> > I suspect that's misleading.
> 
> Yes, it should be mostly trivial.  I just bet the maintainers are
> better at optimizing the low-level assembly code with the variable
> address limit gone than I am.  (See Linus comments on the x86 version
> for example).  And I don't have a physical arm64 to test with so I'd
> have to rely on qemu for any testing.

So I looked at the arm64 code and I don't think it is entirely trivial,
due to the orig_addr_limit saving in the syscall entry path, and due
to all the UAO stuff.  On the plus side it looks to me like
CONFIG_ARM64_UAO and all the code relate to it can go away entirely
if set_fs() is gone.

So if I can trick you guys into submiting a patch on top of:

   http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/set_fs-removal

that would make my life a lot simpler.

  reply	other threads:[~2020-09-01 15:54 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 [this message]
2020-09-02 11:43           ` Mark Rutland
2020-09-02 13:32             ` Christoph Hellwig
2020-09-02 17:23               ` Mark Rutland
2020-09-03  6:56                 ` Christoph Hellwig
2020-09-04 16:00                   ` Mark Rutland

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