Messages in this thread | | | Date | Fri, 11 Aug 2006 19:13:33 -0400 | From | Chuck Ebbert <> | Subject | Re: [patch] i386: annotate the rest of entry.s::nmi |
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In-Reply-To: <44DC496D.76E4.0078.0@novell.com>
On Fri, 11 Aug 2006 09:10:05 +0200, Jan Beulich wrote:
> I understand now, but am still uncertain > about the need to annotate FIX_STACK() - especially since you use > .cfi_undefined, meaning the return point cannot be established anyway. > If at all I'd annotate the initial pushes with either just the normal > CFI_ADJUST_CFA_OFFSET, and the final one with one setting back the > CFA base to the now adjusted frame. That way, until the pushes are > complete the old frame will be used for determining the call origin, > and once complete the (full) new state will be used.
But that's the whole point of the new annotations -- we have just overwritten %esp with a new value and the old assumptions are completely broken:
movl TSS_sysenter_esp0+offset(%esp),%esp; \
After this the old frame cannot be located by using %esp as a base and the new frame is incomplete. So the only choice is to make eip undefined until the new value is available -- if not then the unwinder will try to use whatever random values are on the new frame. Either that or I'm still unclear on how unwind works...
-- Chuck
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