Re: Unwind bug on out of line code called from leaf functions

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2003-11-27 12:34:56
>>>>> On Thu, 27 Nov 2003 12:12:56 +1100, Keith Owens <kaos@sgi.com> said:

  Keith> On Wed, 26 Nov 2003 16:32:00 -0800, 
  Keith> David Mosberger <davidm@napali.hpl.hp.com> wrote:
  >>>>>>> On Thu, 27 Nov 2003 11:12:18 +1100, Keith Owens <kaos@sgi.com> said:
  Keith> We need a generic fix for unwinding through out of line code
  Keith> called from leaf functions and not using br.call.  The
  Keith> obvious solution is to flag all out of line code with an
  Keith> unwind abi field and have the common unwind code reset
  Keith> ar.pfs.  Can I use .unwabi 3, 'o' for out of line?

  >> The .unwabi directive isn't appropriate for that.  If you want such a
  >> feature, please push it through the ABI committee to get it officially
  >> supported.  I've said that before, I think.

  Keith> I disagree, unwabi is exactly what we need for this.  The out
  Keith> of line code is peculiar to Linux, and uses the Linux pt_regs
  Keith> to get the real ar.pfs.  .unwabi 3,i indicates a Linux
  Keith> interrupt frame with all state in pt_regs, .unwabi 3,o
  Keith> indicates a Linux out of line frame with pt_regs.ar_pfs
  Keith> containing the real ar.pfs.  If unwabi 3,i is valid then so
  Keith> is unwabi 3,o.

If you want to support out-of-line code, do it right or don't it at
all.  There is no chance in hell I'm going to accept such hacks and I
also won't bother supporting such gross hacks in libunwind.  EOD.

	--david
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Received on Wed Nov 26 20:35:26 2003

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