Re: [Crash-utility] [PATCH] ARM: fp when unwinding

Hi Mika, On Thu, Oct 6, 2011 at 7:51 PM, Mika Westerberg <mika.westerberg(a)iki.fi&gt; wrote: > On Thu, Oct 06, 2011 at 01:04:07PM +0200, Per Fransson wrote: > >>  The 'struct stackframe' we use to keep unwind state when going from >> one frame to the next (or should I say previous) only contains fp, >> sp, lr and pc, which might be something we should consider changing. >> Even as it stands however, frame.fp is assigned an incorrect value >> for active tasks. Here's a patch to fix that. > > I don't understand how it can be incorred - IIRC unwind tables don't use FP at > all. It is only there because that register can be used for other purposes and > some unwinding instructions might restore it from the stack. > > Have you seen this problem really happening? > Indeed I have. Looking up the pc 0xc02c9650 I find this idx entry: 0xc02c9610 0x000376a4 The insn field directs me to the following EHT: 0x81019b42 which contains two instructions: exec 0x9b : sp = fp exec 0x42 : sp = sp - 0xc An uninitialized fp makes this fail. With my oneliner it works. Regards, Per