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

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/5] x86: Implement __WARN using UD0
Date	2017-03-21 16:50 +0100
Message-ID	<tnucP-5iR-37@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> <tntJN-55L-31@gated-at.bofh.it> <tnu38-5ee-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Mar 21, 2017 at 10:32:52AM -0500, Josh Poimboeuf wrote:
> On Tue, Mar 21, 2017 at 04:14:46PM +0100, Peter Zijlstra wrote:
> > > > +static int fixup_bug(struct pt_regs *regs, int trapnr)
> > > > +{
> > > > +	if (trapnr != X86_TRAP_UD)
> > > > +		return 0;
> > > > +
> > > > +	switch (report_bug(regs->ip, regs)) {
> > > > +	case BUG_TRAP_TYPE_NONE:
> > > > +	case BUG_TRAP_TYPE_BUG:
> > > > +		break;
> > > > +
> > > > +	case BUG_TRAP_TYPE_WARN:
> > > > +		regs->ip += 2;
> > > > +		return 1;
> > > 
> > > For self-documentation purposes, maybe use a define for the length of
> > > the ud0 instruction?
> > 
> > Well, UD0 and UD2 really. LENGTH_UD0_OR_UD2 is a bit of a fail, name
> > wise.
> 
> Why UD2?  Warnings are UD0-only, no?  What about UD0_LEN?  Or at least a
> comment would be helpful I think.

Oh, right, we only resume on WARN,.. Doh.

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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