Re: [Linux-ia64] Unwind can load wrong data from pt_regs

Keith Owens
2002-12-09T22:04:25Z

On Mon, 9 Dec 2002 13:21:07 -0800,
David Mosberger <davidm@napali.hpl.hp.com> wrote:
>>>>>> On Mon, 09 Dec 2002 19:35:03 +1100, Keith Owens <kaos@sgi.com> said:
>
> Keith> This implicitly assumes that when a fr or br register is
> Keith> required from pt_regs, info->sp is pointing to pt_regs. But
> Keith> info->sp is modified as the code unwinds through each
> Keith> function. The above code only gives correct results for
> Keith> register lookups from the failing function. Unwinding and
> Keith> accessing a fr or br register from earlier functions loads
> Keith> incorrect values for those registers.
>
>Yes, this is something that has been fixed already in the user-level
>libunwind. It's not hard to fix, just someone needs to get around to
>do it. I don't think it's a critical issue, since it only happens for
>nested traps. I assume you saw this with kdb?

How did you guess :). I will look at libunwind and do a kernel fix.