Messages in this thread | | | Date | Thu, 28 Sep 2006 00:00:19 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Put the BUG __FILE__ and __LINE__ info out of line |
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On Wed, 27 Sep 2006 23:49:49 -0700 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Andrew Morton wrote: > > hm. Bigger vmlinux, smaller .text. > > > > Yep. > > > It means that we'll hit handle_BUG with that extra EIP pushed on the stack. > > What does that do to the stack trace, and to the unwinder? > > > Dunno. I was hoping Andi would pop up with the appropriate CFI gunk, if > necessary. But the reason for making it a call was to make it as > unwindable as possible. > > > It'll also muck up the displayed EIP, not that that matters a lot (well, it > > might matter a bit if the BUG is in an inlined function). > > > > We could get the correct EIP by fishing it off the stack (and subtracting > > five from it?) > > > > Yes, that's possible. > > > Or we could assume that BUG doesn't return (it doesn't) and make that call > > a jmp. But then we'd really lose the EIP. > > Right. Or it could save the EIP along with the line and filename. >
Plan #17 is to just put the BUG inline and then put the EIP+file*+line into a separate section, then search that section at BUG time to find the record whose EIP points back at this ud2a.
It's a bit messy for modules, but it minimises the .text impact and keeps disassembly happy, no?
And if done right it can probably be used by other architectures. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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