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From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: pabeni@redhat.com, Jens Axboe <axboe@kernel.dk>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	bp@alien8.de, Peter Anvin <hpa@zytor.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrew Lutomirski <luto@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	dvlasenk@redhat.com, brgerst@gmail.com,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: only use ERMS for user copies for larger sizes
Date: Thu, 22 Nov 2018 12:21:19 +0100	[thread overview]
Message-ID: <20181122112119.GA108224@gmail.com> (raw)
In-Reply-To: <20181122111341.GA107459@gmail.com>


* Ingo Molnar <mingo@kernel.org> wrote:

> So I dug into this some more:
> 
> 1)
> 
> Firstly I tracked down GCC bloating the might_fault() checks and the 
> related out-of-line code exception handling which bloats the full 
> generated function.

Sorry, I mis-remembered that detail when I wrote the email: it was 
CONFIG_HARDENED_USERCOPY=y and its object size checks that distros enable 
- and I disabled that option to simplify the size analysis.

(might_fault() doesn't have inline conditionals so shouldn't have any 
effect on the generated code.)

Thanks,

	Ingo

  reply	other threads:[~2018-11-22 11:21 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <02bfc577-32a5-66be-64bf-d476b7d447d2@kernel.dk>
2018-11-20 20:24 ` [PATCH] x86: only use ERMS for user copies for larger sizes Jens Axboe
2018-11-21  6:36 ` Ingo Molnar
2018-11-21 13:32   ` Jens Axboe
2018-11-21 13:44     ` Denys Vlasenko
2018-11-22 17:36       ` David Laight
2018-11-22 17:52         ` Linus Torvalds
2018-11-22 18:06           ` Andy Lutomirski
2018-11-22 18:58             ` Linus Torvalds
2018-11-23  9:34               ` David Laight
2018-11-23 10:12                 ` David Laight
2018-11-23 16:36                   ` Linus Torvalds
2018-11-23 17:42                     ` Linus Torvalds
2018-11-23 18:39                       ` Andy Lutomirski
2018-11-23 18:44                         ` Linus Torvalds
2018-11-23 19:11                           ` Andy Lutomirski
2018-11-26 10:12                             ` David Laight
2018-11-26 10:01                     ` David Laight
2018-11-26 10:26                     ` David Laight
2019-01-05  2:38                       ` Linus Torvalds
2019-01-07  9:55                         ` David Laight
2019-01-07 17:43                           ` Linus Torvalds
2019-01-08  9:10                             ` David Laight
2019-01-08 18:01                               ` Linus Torvalds
2018-11-21 13:45     ` Paolo Abeni
2018-11-21 17:27       ` Linus Torvalds
2018-11-21 18:04         ` Jens Axboe
2018-11-21 18:26           ` Andy Lutomirski
2018-11-21 18:43             ` Linus Torvalds
2018-11-21 22:38               ` Andy Lutomirski
2018-11-21 18:16         ` Linus Torvalds
2018-11-21 19:01           ` Linus Torvalds
2018-11-22 10:32             ` Ingo Molnar
2018-11-22 11:13               ` Ingo Molnar
2018-11-22 11:21                 ` Ingo Molnar [this message]
2018-11-23 16:40                 ` Josh Poimboeuf
2018-11-22 16:55               ` Linus Torvalds
2018-11-22 17:26                 ` Andy Lutomirski
2018-11-22 17:35                   ` Linus Torvalds
2018-11-24  6:09           ` Jens Axboe

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