Re: 2.6 unwind problem in kernel/sched.c

From: David Mosberger <>
Date: 2004-03-11 19:14:51
>>>>> On Tue, 09 Mar 2004 11:50:56 +1100, Keith Owens <> said:

  Keith> 2.6.4-rc2, gcc 3.2.3, binutils  kernel/sched.c
  Keith> does schedule() -> context_switch() -> switch_to() followed
  Keith> by finish_task_switch().  finish_task_switch() calls
  Keith> finish_arch_switch() which enables interrupts.  If there is
  Keith> an interrupt pending, that interrupt runs at schedule+0x1090
  Keith> (ssm).

  Keith> At this point we are running on the new stack but cr_iip
  Keith> points into schedule() so the unwinder uses schedule's unwind
  Keith> data (b0, ar.pfs in r60, r61).  r60 and r61 are loaded from
  Keith> bsp on the new stack, they are completely wrong and the
  Keith> unwind is useless.

I must be missing something. After switch_to() you're fully switched
to the new task so I don't see why an interrupt during
finish_arch_switch() would mess up the backtrace.  Since CR.IIP points
to schedule() and since the interrupt handler will return to that
instruction after its done, the state at that instruction better be

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Received on Thu Mar 11 03:15:06 2004

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