Re: [PATCH 1/5] x86: Implement __WARN using UD0

From	Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/5] x86: Implement __WARN using UD0
Date	2017-03-22 15:20 +0100
Message-ID	<tnPhg-3Fu-23@gated-at.bofh.it> (permalink)
References	<tm7Lj-4jK-7@gated-at.bofh.it> <tm7Lj-4jK-15@gated-at.bofh.it> <tnsNI-4r2-5@gated-at.bofh.it> <tnK7T-81a-5@gated-at.bofh.it>
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On Wed, Mar 22, 2017 at 09:47:06AM +0100, Peter Zijlstra wrote:
> 
> A little like so then.
> 
> ---
> Subject: x86: Implement __WARN using UD0
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Thu Feb 2 14:43:51 CET 2017
> 
> By using "UD0" for WARNs we remove the function call and its possible
> __FILE__ and __LINE__ immediate arguments from the instruction stream.
> 
> Total image size will not change much, what we win in the instruction
> stream we'll loose because of the __bug_table entries. Still, saves on
> I$ footprint and the total image size does go down a bit.
> 
>    text    data     bss     dec     hex filename
> 10702123        4530992  843776 16076891         f5505b defconfig-build/vmlinux.0
> 10682460        4530992  843776 16057228         f5038c defconfig-build/vmlinux.1
> 
> (um didn't seem to use GENERIC_BUG at all, so remove it)
> 
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Richard Weinberger <richard.weinberger@gmail.com>
> Cc: Arjan van de Ven <arjan@linux.intel.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Looks good, thanks!

Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>

-- 
Josh

Thread

[PATCH 0/5] x86 optimizations Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100
  [PATCH 3/5] atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100
  [PATCH 5/5] x86,atomic: Use atomic_try_cmpxchg Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100
  [PATCH 1/5] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100
    Re: [PATCH 1/5] x86: Implement __WARN using UD0 Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-21 15:20 +0100
      Re: [PATCH 1/5] x86: Implement __WARN using UD0 Arjan van de Ven <arjan@linux.intel.com> - 2017-03-21 16:20 +0100
      Re: [PATCH 1/5] x86: Implement __WARN using UD0 Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-21 16:40 +0100
        Re: [PATCH 1/5] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-03-21 16:50 +0100
      Re: [PATCH 1/5] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-03-21 17:50 +0100
      Re: [PATCH 1/5] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-03-22 09:50 +0100
        Re: [PATCH 1/5] x86: Implement __WARN using UD0 Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-22 15:20 +0100
  [PATCH 4/5] refcount: Use atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100
  [PATCH 2/5] bug: Add _ONCE logic to report_bug() Peter Zijlstra <peterz@infradead.org> - 2017-03-17 22:40 +0100

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