problems with perf probe and system libraries

[David Ahern]

Hi Masami:

I have been looking at perf-probe again and having a number of problems 
with top of tree.

Here's the first one I have isolated:

$ perf probe -x /lib64/libc-2.18.so -a 'malloc  size=%di'
Probe point 'malloc' not found.
  Error: Failed to add events.

$ perf probe -x /lib64/libc-2.18.so -F | grep malloc
malloc
malloc@plt
malloc_atfork
malloc_check
malloc_consolidate
malloc_hook_ini
malloc_info
malloc_printerr
mallochook
ptmalloc_init
ptmalloc_init.part.8
ptmalloc_lock_all
ptmalloc_unlock_all
ptmalloc_unlock_all2
tr_mallochook

$ perf probe -x /lib64/libc-2.18.so -a 'malloc=malloc size=%di'
Probe point 'malloc' not found.
  Error: Failed to add events.

A year ago (v3.12) this worked fine so I did a git bisect which points to:

commit fb7345bbf7fad9bf72ef63a19c707970b9685812
Author: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Date:   Thu Dec 26 05:41:53 2013 +0000

    perf probe: Support basic dwarf-based operations on uprobe events

I have tried top of tree on Fedora 16, 18 and 20 with a variety of 
kernels - and a variety of results. Reverting to 
8a613d40e389b723fd5889ac8d4033ed4030be31 which is the commit before this 
one and it works again.

David
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