[Bug translator/13284] New: failure to resolve kernel global e.g. jiffies

[Bug translator/13284] New: failure to resolve kernel global e.g. jiffies

[fche at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13284

             Bug #: 13284
           Summary: failure to resolve kernel global e.g. jiffies
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap@sourceware.org
        ReportedBy: fche@redhat.com
    Classification: Unclassified


riel reports:

stap -vp2 -e 'probe kernel.function("schedule_timeout") { println($jiffies)}' 
Pass 1: parsed user script and 83 library script(s) using
205236virt/28136res/2824shr kb, in 250usr/30sys/278real ms.
semantic error: failed to retrieve location attribute for local 'jiffies'
(dieoffset: 0x7cb91f): identifier '$jiffies' at <input>:1:53
        source: probe kernel.function("schedule_timeout") { println($jiffies)}
                                                                    ^
Note that the variable itself resolves, just misses location list info, which
is
kind of natural since it's a global.

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[Bug translator/13284] failure to resolve kernel global e.g. jiffies

[riel at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13284

Rik van Riel <riel at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |riel at redhat dot com

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[Bug translator/13284] failure to resolve kernel global e.g. jiffies

[mjw at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13284

Mark Wielaard <mjw at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mjw at redhat dot com

--- Comment #1 from Mark Wielaard <mjw at redhat dot com> 2011-10-18 12:04:56 UTC ---
We should in theory already be able to do that through vardie_from_symtable().

See dwflpp::literal_stmt_for_local():

      // If it is an external variable try the symbol table. PR10622.
      if (dwarf_attr_integrate (&vardie, DW_AT_external, &attr_mem) != NULL
          && vardie_from_symtable (&vardie, &addr_loc.number) != 0)

That should trigger, since I see:

46983: ffffffff81b89880      0 NOTYPE  GLOBAL DEFAULT      ABS jiffies

But it doesn't since vardie_from_symtable() has:

      if (symname
          && ! strcmp (name, symname)
          && sym.st_shndx != SHN_UNDEF
          && GELF_ST_TYPE (sym.st_info) == STT_OBJECT)

So, we need to be a little more creative and also allow NOTYPE?

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[Bug translator/13284] failure to resolve kernel global e.g. jiffies

[mjw at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13284

Mark Wielaard <mjw at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #2 from Mark Wielaard <mjw at redhat dot com> 2011-10-18 12:44:19 UTC ---
And it really was that simple:

commit d124d4decd2e1ab45727f2b4d9994a377998cb41
Author: Mark Wielaard <mjw@redhat.com>
Date:   Tue Oct 18 14:28:59 2011 +0200

    PR13284 Failure to resolve kernel global e.g. jiffies.

    * dwflpp.cxx (vardie_from_symtable): Also accept STT_NOTYPE. Some global
      don't have a type associated with them.
    * testsuite/buildok/pr13284.stp: New testcase.

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