Re: Semantic error with demo scripts..

[Li Guanglei <guanglei at cn dot ibm dot com>]

S. P. Prasanna wrote:
> Hi,
>
>
> # ./proc_snoop.stp
> semantic error: probe point mismatch at position 0 (alternatives: _process begin end hrtimer(string) ioblock ioscheduler kernel module(string) netdev never pagefault process scheduler scsi syscall timer)
> while: resolving probe point signal.send
> semantic error: probe point mismatch at position 0 (alternatives: _process begin end hrtimer(string) ioblock ioscheduler kernel module(string) netdev never pagefault process scheduler scsi syscall timer)
> while: resolving probe point signal.handle
> Pass 2: analysis failed.  Try again with more '-v' (verbose) options.

I tried on my ppc64, it will report:
semantic error: failed to retrieve location attribute for local 'sig' 
(dieoffset: 0xad505): identifier '$sig' at 
/usr/local/share/systemtap/tapset/signal.stp:377:11

It is because handle_signal is optimized as inline and currently we 
can't visit the arguments of inline function due to the  absent DWARF 
info.

> # stap -v -g sched_snoop.stp Pass 1: parsed user script and 25 library script(s) in 230usr/0sys/235real ms.
> semantic error: no match for probe point
> while: resolving probe point kernel.inline("pull_task")
> semantic error: no match for probe point
> while: resolving probe point scheduler.migrate
> Pass 2: analyzed script: 5 probe(s), 29 function(s), 1 global(s) in 320usr/50sys/365real ms.
> Pass 2: analysis failed.  Try again with more '-v' (verbose) options.

I failed too on a 4-way ppc64/2.6.17.13/elfutils 0.123. I looked at 
the DWARF info of pull_task, but it looks good to me. Didn't figure 
out why it failed. Here is the DWARF info:

...
 <2><332512>: Abbrev Number: 58 (DW_TAG_inlined_subroutine)
     DW_AT_sibling     : <33254c>
     DW_AT_abstract_origin: <332621>
     DW_AT_ranges      : 88224
     DW_AT_call_file   : 0
     DW_AT_call_line   : 0
 <3><332521>: Abbrev Number: 71 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <33262f>
 <3><332526>: Abbrev Number: 59 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <33263b>
     DW_AT_location    : 446571 (location list)
....

 <1><332621>: Abbrev Number: 87 (DW_TAG_subprogram)
     DW_AT_sibling     : <332676>
     DW_AT_name        : (indirect string, offset: 0x168bf): pull_task
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1802
     DW_AT_prototyped  : 1
     DW_AT_inline      : 1      (inlined)
 <2><33262f>: Abbrev Number: 86 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x16dab): src_rq
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1800
     DW_AT_type        : <32fe63>
 <2><33263b>: Abbrev Number: 86 (DW_TAG_formal_parameter)
...


> # ./sys.stp
> semantic error: no match for probe point
> while: resolving probe point kernel.function("sys_chown16")
> semantic error: no match for probe point
> while: resolving probe point kernel.function("sys_fchown16")
> semantic error: no match for probe point
> while: resolving probe point kernel.function("sys_getgid16")
It works fine for me. I looked at the latest codes in CVS, and found 
these probes are already optional.