[Bug uprobes/6828] uprobe presence interferes with dd signal handling

["jkenisto at us dot ibm dot com" <sourceware-bugzilla at sourceware dot org>]

------- Additional Comments From jkenisto at us dot ibm dot com  2008-08-21 23:26 -------
Created an attachment (id=2919)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2919&action=view)
utrace-based module that afflicts dd similarly

I see this same failure in the absence of uprobes and SystemTap, just by
tracing dd with the attached module (using old utrace, at least -- haven't
tried the new one).  The use of a report_signal callback is the most obvious
common denominator.

Roland, could you take a look at sigtrace.c and let me know if it's doing
anything obviously wrong?  If so, uprobes may have the same problem.

In any case, it looks like the SEGV is because dd is trying to execute at
address 0 instead of at the handler address.  Everything looks pretty good up
to handle_signal(), but if I put a probepoint on the handler, it doesn't get
hit.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6828

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