This is the mail archive of the
elfutils-devel@sourceware.org
mailing list for the elfutils project.
Re: Way to disable relocations being performed
- From: Arnaldo Carvalho de Melo <acme at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Tue, 30 Jun 2009 17:50:36 -0300
- Subject: Re: Way to disable relocations being performed
Em Sun, Jun 28, 2009 at 02:07:35PM -0700, Roland McGrath escreveu:
> > For me it is not relevant at all, I just need the type definitions and
> > function parameter list, variable name/type, etc. Only in very specific
> > cases I want addresses, and even then no need for relocations in most
> > cases.
>
> If you are dealing with an ET_REL file on an SHT_RELA architecture, then
> you need relocation of the pointers inside and between the different DWARF
> sections. In short, you can't handle an ET_REL file at all without doing
> some kind of relocation.
>
> > I'll look at the dwfl internals to figure out where is that it ends up using
> > dwfl_linux_kernel_ prefixed routines...
>
> Well, just set a breakpoint and look at the backtrace from your code.
> The only implicit calls to any such things in libdwfl come from the argp
> callbacks for -k/-K options.
Nevermind, it was a bug in the kernel perf tools, getting confused with
prelinked libraries :-\
I fixed it and now it makes more sense and its in line with what oprofile
reports:
[acme(a)doppio pahole]$ perf report --sort comm,dso,symbol --dsos /usr/lib64/libdw-0.141.so | head -20
#
# (135909 samples)
#
# Overhead Command Shared Object Symbol
# ........ ................ ......................... ......
#
43.39% pahole /usr/lib64/libdw-0.141.so [.] __libdw_find_attr
27.16% pahole /usr/lib64/libdw-0.141.so [.] __libdw_form_val_len
5.79% pahole /usr/lib64/libdw-0.141.so [.] lookup
4.99% pahole /usr/lib64/libdw-0.141.so [.] findcu_cb
4.14% pahole /usr/lib64/libdw-0.141.so [.] __dwarf_attr_internal
2.14% pahole /usr/lib64/libdw-0.141.so [.] __dwarf_siblingof_internal
1.13% pahole /usr/lib64/libdw-0.141.so [.] __libdw_findcu
0.98% pahole /usr/lib64/libdw-0.141.so [.] __libdw_get_uleb128
0.97% pahole /usr/lib64/libdw-0.141.so [.] dwarf_tag
0.94% pahole /usr/lib64/libdw-0.141.so [.] __libdw_formref
0.87% pahole /usr/lib64/libdw-0.141.so [.] __dwarf_formsdata_internal
0.83% pahole /usr/lib64/libdw-0.141.so [.] dwarf_decl_file
0.79% pahole /usr/lib64/libdw-0.141.so [.] dwarf_getsrclines
[acme(a)doppio pahole]$
Sorry for the noise,
- Arnaldo