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[Bug translator/9768] New: cannot read userspace function parameter


Systemtap can't read the "mutex" parameter in pthread_mutex_lock.
user.stp:
probe process("/lib/libpthread-2.9.so").statement("__pthread_mutex_lock") {
        printf("[%d] %s\n", pid(), $$parms)
}

> stap user.stp
[2808] mutex=? 
[2808] mutex=? 
...

> stap user.stp -p2
process("/lib/libpthread-2.9.so").statement("__pthread_mutex_lock@/usr/src/debug/glibc-
20081113T2206/nptl/pthread_mutex_lock.c:43") /* pc=.dynamic+0x79e0 */ /* <- 
process("/lib/libpthread-2.9.so").statement("__pthread_mutex_lock") */

I tried different line numbers (40...44 for example) but nothing changes.
I also tried printing $$vars instead of $$parms (varying line # as well):
[2808] mutex=? oldval=? id=? retval=? __PRETTY_FUNCTION__=? 
[2808] mutex=? oldval=? id=? retval=? __PRETTY_FUNCTION__=? 
...

Gdb can read the parameter:
Breakpoint 2, __pthread_mutex_lock (mutex=0x836c02c) at pthread_mutex_lock.c:43
(gdb) p mutex
$1 = (pthread_mutex_t *) 0x836c02c

Changing the probe to libc alias doesn't help either "probe process("/lib/libc-
2.9.so").statement("pthread_mutex_lock").

I'm running systemtap (0.8/0.137 git branch master) on Fedora 10 (2.6.27.9-159.fc10.i686)

-- 
           Summary: cannot read userspace function parameter
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: tralamazza at gmail dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=9768

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