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Re: return probes and stack traces
- From: Roland McGrath <roland at redhat dot com>
- To: Jim Keniston <jkenisto at us dot ibm dot com>
- Cc: SystemTAP <systemtap at sources dot redhat dot com>
- Date: Tue, 28 Jun 2005 17:13:28 -0700
- Subject: Re: return probes and stack traces
> I'm not sure what you have in mind. When the return-probe handler is
> called, the return address has already been popped off the stack by the
> return instruction.
In that case the "real return address" being talked about is the "real PC"
at that point, and regs->eip (for x86) should be updated before the handler
is run rather than after. What I have in mind is simply the principle that
the observers get shown "magically suspended" machine state rather than
machine state that includes implementation artifacts.