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Date:   Thu, 22 Nov 2018 12:21:19 +0100
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,
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        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
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* 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