[Bug tapsets/1966] New: module function probe failed

["guanglei at cn dot ibm dot com" <sourceware-bugzilla at sourceware dot org>]

Today I tried to add probe points to some functions in modules, ex:

probe module("scsi_mod").function("scsi_dispatch_cmd")
{
   log("here")
}

but stap will give the error:

root:/root>stap a.stp
WARNING: cannot find module scsi_mod debuginfo: relocation refers to undefined
symbol
semantic error: no match for probe point
     while: resolving probe point module("scsi_mod").function("scsi_dispatch_cmd")
Pass 2: analysis failed.  Try again with '-v' (verbose) option.

And I got the same kind of error when I probed module("ext3").function("*")

But when I tried to probe module("sd_mod").function("*"), it succeed.

After looked into the systemTap src, I found this error was generated by calling
__libdwfl_relocate:

Breakpoint 4, load_dw (mod=0x9aeff90, debugfile=0x9aeffc4) at
dwfl_module_getdwarf.c:306
306     result = __libdwfl_relocate (mod, debugfile->elf);
(gdb) p result
$72 = DWFL_E_RELUNDEF
(gdb) p *debugfile
$73 = {name = 0x9af17b8 
"/usr/lib/debug/lib/modules/2.6.9-22.17.EL.root/kernel/drivers/scsi/scsi_mod.ko.debug",
fd = 8, elf = 0x9af1820, bias = 0}

The environment of my systems: 2.6.9-22.17.EL, elfutils-xxx-0.116-0.1, gcc
3.4.4, ppc64 and i386

I am not sure if it's a bug of elfutils or a bug of systemTap.

-- 
           Summary: module function probe failed
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: critical
          Priority: P2
         Component: tapsets
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: guanglei at cn dot ibm dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=1966

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