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Re: stap error: no match while resolving probe point kernel.function("do_mmap_pgoff@mm/mmap.c:901")
- From: Mark Wielaard <mjw at redhat dot com>
- To: a qi <free4machine at gmail dot com>
- Cc: systemtap at sourceware dot org
- Date: Mon, 22 Feb 2010 13:13:20 +0100
- Subject: Re: stap error: no match while resolving probe point kernel.function("do_mmap_pgoff@mm/mmap.c:901")
- References: <962a47301002211927i40894ae8ka4638b201fad8064@mail.gmail.com>
Hi,
On Mon, 2010-02-22 at 11:27 +0800, a qi wrote:
> ./t15.stp --vp 01
> semantic error: libdw failure (dwarf_getsrc_file): no matching address range
> semantic error: no match while resolving probe point
> kernel.function("do_mmap_pgoff@mm/mmap.c:901")
> semantic error: no probes found
> [...]
> when I try to run this simple stap script which print the vaule of
> correct_wcount ,
>
> # t15.stp
> probe kernel.function("do_mmap_pgoff@mm/mmap.c:901"){
> printf("the correct_wcount is : %d\n ",$correct_wcount)
> }
Does it work when you don't put in a line number?
(my local kernel install doesn't have a correct_wcount variable)
If you need to try at a specific line, instead of at the function start,
then you might also try a kernel.statement probe instead of a
kernel.function probe.
> and here is the output of 'stap -l ' :
> stap -l 'kernel.function("do_mmap_pgoff@mm/mmap.c")'
> kernel.function("do_mmap_pgoff@mm/mmap.c:901")
Certainly odd. Locally I get:
$ stap -l 'kernel.function("do_mmap_pgoff@mm/mmap.c")'
kernel.function("do_mmap_pgoff@mm/mmap.c:928")
and probing at that explicit function/line does work:
$ stap -e 'probe kernel.function("do_mmap_pgoff@mm/mmap.c:928")
{ log(pp()); exit(); }'
kernel.function("do_mmap_pgoff@mm/mmap.c:928")
There was a fixlet in elfutils for dwarf_getsrc_file() some time back:
commit e23e9e7de7d070a47ef641abeaf272467a1cff4c
Author: Roland McGrath <roland@redhat.com>
Date: Tue Jul 21 18:14:52 2009 -0700
Fix dwarf_getsrc_file handling empty CUs.
But I don't know if that is related. You might want to check if using a
newer elfutils will help.
Cheers,
Mark