gdb cannot access memory in attached process when attempting to set breakpoint

Question

I am debugging a user defined function (found in customly created libafd.so) of the postgres process.

In psql (runs postgres process) getting out the pid of the process:

SELECT pg_backend_pid();
pg_backend_pid 
----------------
      22648
(1 row)

attaching the gdb to the process (run as root):

# gdb libafd.so -p 22648

Getting a bunch of symbols loaded, some failed:

GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>...
Reading symbols from /usr/lib/postgresql/9.1/lib/libafd.so...done.
Attaching to program: /usr/lib/postgresql/9.1/lib/libafd.so, process 22648
Reading symbols from /usr/lib/x86_64-linux-gnu/libxml2.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libxml2.so.2
Reading symbols from /lib/x86_64-linux-gnu/libpam.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libpam.so.0
Reading symbols from /lib/x86_64-linux-gnu/libssl.so.1.0.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libssl.so.1.0.0
Reading symbols from /lib/x86_64-linux-gnu/libcrypto.so.1.0.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libcrypto.so.1.0.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libkrb5.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libkrb5.so.3
Reading symbols from /lib/x86_64-linux-gnu/libcom_err.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libcom_err.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2
Reading symbols from /lib/x86_64-linux-gnu/libdl.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libdl-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libdl.so.2
Reading symbols from /lib/x86_64-linux-gnu/libm.so.6...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libm-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libm.so.6
Reading symbols from /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2
Reading symbols from /lib/x86_64-linux-gnu/libc.so.6...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libc.so.6
Reading symbols from /lib/x86_64-linux-gnu/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libz.so.1
Reading symbols from /usr/lib/x86_64-linux-gnu/liblzma.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/liblzma.so.5
Reading symbols from /usr/lib/x86_64-linux-gnu/libk5crypto.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libk5crypto.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libkrb5support.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libkrb5support.so.0
Reading symbols from /lib/x86_64-linux-gnu/libkeyutils.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libkeyutils.so.1
Reading symbols from /lib/x86_64-linux-gnu/libresolv.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libresolv-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libresolv.so.2
Reading symbols from /lib/x86_64-linux-gnu/libpthread.so.0...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libpthread-2.15.so...done.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
done.
Loaded symbols for /lib/x86_64-linux-gnu/libpthread.so.0
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.15.so...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/liblber-2.4.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/liblber-2.4.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/libsasl2.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libsasl2.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/libgssapi.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libgssapi.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libgnutls.so.26...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libgnutls.so.26
Reading symbols from /lib/x86_64-linux-gnu/libgcrypt.so.11...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libgcrypt.so.11
Reading symbols from /usr/lib/x86_64-linux-gnu/libheimntlm.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libheimntlm.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libkrb5.so.26...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libkrb5.so.26
Reading symbols from /usr/lib/x86_64-linux-gnu/libasn1.so.8...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libasn1.so.8
Reading symbols from /usr/lib/x86_64-linux-gnu/libhcrypto.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libhcrypto.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libroken.so.18...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libroken.so.18
Reading symbols from /usr/lib/x86_64-linux-gnu/libtasn1.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libtasn1.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libp11-kit.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libp11-kit.so.0
Reading symbols from /lib/x86_64-linux-gnu/libgpg-error.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libgpg-error.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libwind.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libwind.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libheimbase.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libheimbase.so.1
Reading symbols from /usr/lib/x86_64-linux-gnu/libhx509.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libhx509.so.5
Reading symbols from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
Reading symbols from /lib/x86_64-linux-gnu/libcrypt.so.1...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libcrypt-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libcrypt.so.1
Reading symbols from /lib/x86_64-linux-gnu/libnss_files.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libnss_files-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libnss_files.so.2
Reading symbols from /lib/x86_64-linux-gnu/libnss_compat.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libnss_compat-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libnss_compat.so.2
Reading symbols from /lib/x86_64-linux-gnu/libnsl.so.1...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libnsl-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libnsl.so.1
Reading symbols from /lib/x86_64-linux-gnu/libnss_nis.so.2...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/libnss_nis-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libnss_nis.so.2
Reading symbols from /usr/lib/postgresql/9.1/lib/libafd.so...done.
Loaded symbols for /usr/lib/postgresql/9.1/lib/libafd.so
Reading symbols from /usr/lib/libgdal.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgdal.so.1
Reading symbols from /usr/lib/libspatialindex.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libspatialindex.so.1
Reading symbols from /usr/lib/libboost_iostreams.so.1.46.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libboost_iostreams.so.1.46.1
Reading symbols from /usr/lib/libboost_serialization.so.1.46.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libboost_serialization.so.1.46.1
Reading symbols from /usr/lib/libproj.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libproj.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libQtSql.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libQtSql.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libQtCore.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libQtCore.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libstdc++.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libstdc++.so.6
Reading symbols from /lib/x86_64-linux-gnu/libgcc_s.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libgcc_s.so.1
Reading symbols from /usr/lib/libarmadillo.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libarmadillo.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/libpoppler.so.19...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libpoppler.so.19
Reading symbols from /usr/lib/libgeos_c.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgeos_c.so.1
Reading symbols from /usr/lib/libepsilon.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libepsilon.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libodbc.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libodbc.so.1
Reading symbols from /usr/lib/x86_64-linux-gnu/libodbcinst.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libodbcinst.so.1
Reading symbols from /lib/x86_64-linux-gnu/libexpat.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libexpat.so.1
Reading symbols from /usr/lib/libxerces-c.so.28...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxerces-c.so.28
Reading symbols from /usr/lib/x86_64-linux-gnu/libjasper.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libjasper.so.1
Reading symbols from /usr/lib/libnetcdf.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libnetcdf.so.6
Reading symbols from /usr/lib/libhdf5.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libhdf5.so.6
Reading symbols from /usr/lib/libmfhdfalt.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libmfhdfalt.so.0
Reading symbols from /usr/lib/libdfalt.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdfalt.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/libgif.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libgif.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libjpeg.so.8...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libjpeg.so.8
Reading symbols from /lib/x86_64-linux-gnu/libpng12.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libpng12.so.0
Reading symbols from /usr/lib/libpq.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpq.so.5
Reading symbols from /usr/lib/x86_64-linux-gnu/libdapclient.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libdapclient.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libdap.so.11...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libdap.so.11
Reading symbols from /usr/lib/libspatialite.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libspatialite.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
Reading symbols from /lib/x86_64-linux-gnu/libbz2.so.1.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libbz2.so.1.0
Reading symbols from /lib/x86_64-linux-gnu/librt.so.1...Reading symbols from /usr/lib/debug/lib/x86_64-linux-gnu/librt-2.15.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/librt.so.1
Reading symbols from /lib/x86_64-linux-gnu/libglib-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libglib-2.0.so.0
Reading symbols from /usr/lib/libblas.so.3gf...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libblas.so.3gf
Reading symbols from /usr/lib/liblapack.so.3gf...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/liblapack.so.3gf
Reading symbols from /usr/lib/x86_64-linux-gnu/liblcms2.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/liblcms2.so.2
Reading symbols from /usr/lib/x86_64-linux-gnu/libtiff.so.4...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libtiff.so.4
Reading symbols from /usr/lib/x86_64-linux-gnu/libfreetype.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libfreetype.so.6
Reading symbols from /usr/lib/x86_64-linux-gnu/libfontconfig.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libfontconfig.so.1
Reading symbols from /usr/lib/libgeos-3.3.8.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgeos-3.3.8.so
Reading symbols from /usr/lib/x86_64-linux-gnu/libltdl.so.7...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libltdl.so.7
Reading symbols from /usr/lib/libicuuc.so.48...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libicuuc.so.48
Reading symbols from /usr/lib/libhdf5_hl.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libhdf5_hl.so.6
Reading symbols from /usr/lib/x86_64-linux-gnu/libfreexl.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libfreexl.so.1
Reading symbols from /usr/lib/x86_64-linux-gnu/libidn.so.11...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libidn.so.11
Reading symbols from /usr/lib/x86_64-linux-gnu/librtmp.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/librtmp.so.0
Reading symbols from /lib/x86_64-linux-gnu/libpcre.so.3...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libpcre.so.3
Reading symbols from /usr/lib/x86_64-linux-gnu/libgfortran.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libgfortran.so.3
Reading symbols from /usr/lib/libicudata.so.48...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libicudata.so.48
Reading symbols from /usr/lib/x86_64-linux-gnu/libquadmath.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libquadmath.so.0
Reading symbols from /usr/lib/x86_64-linux-gnu/gconv/UTF-16.so...Reading symbols from /usr/lib/debug/usr/lib/x86_64-linux-gnu/gconv/UTF-16.so...done.
done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/gconv/UTF-16.so
Reading symbols from /usr/lib/libicui18n.so.48...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libicui18n.so.48
Reading symbols from /usr/lib/x86_64-linux-gnu/qt4/plugins/sqldrivers/libqsqlite.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/qt4/plugins/sqldrivers/libqsqlite.so
Reading symbols from /usr/lib/x86_64-linux-gnu/qt4/plugins/sqldrivers/libqsqlpsql.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/qt4/plugins/sqldrivers/libqsqlpsql.so
0x00002b3b1ed34c22 in __libc_recv (fd=8, buf=0xb0da00, n=8192, 
flags=<optimized out>) at ../sysdeps/unix/sysv/linux/x86_64/recv.c:30
30  ../sysdeps/unix/sysv/linux/x86_64/recv.c: No such file or directory.

checking the function I am interested to debug in gdb:

(gdb) info functions libafd_traj_quality
All functions matching regular expression "libafd_traj_quality":

File ../libAFD/libafd.cpp:
Datum libafd_traj_quality(FunctionCallInfo);
const Pg_finfo_record *pg_finfo_libafd_traj_quality();
Datum libafd_traj_quality(FunctionCallInfo);
const Pg_finfo_record *pg_finfo_libafd_traj_quality();
(gdb) 

Trying to set up the breakpoint and getting the error:

(gdb) b libafd_traj_quality
Cannot access memory at address 0x26c01f
(gdb)

How can I set a breakpoint on my function???

Additional Info:

# cat /proc/22648/maps  | grep libafd
2b3b2556e000-2b3b25a82000 r-xp 00000000 08:01 5379086                    /usr/lib/postgresql/9.1/lib/libafd.so
2b3b25a82000-2b3b25c82000 ---p 00514000 08:01 5379086                    /usr/lib/postgresql/9.1/lib/libafd.so
2b3b25c82000-2b3b25c88000 r--p 00514000 08:01 5379086                    /usr/lib/postgresql/9.1/lib/libafd.so
2b3b25c88000-2b3b25c9a000 rw-p 0051a000 08:01 5379086                    /usr/lib/postgresql/9.1/lib/libafd.so

# nm -as /usr/lib/postgresql/9.1/lib/libafd.so | grep libafd_traj_quality
00000000003d4788 r _ZZ28pg_finfo_libafd_traj_qualityE8my_finfo
000000000026c01f T libafd_traj_quality
000000000026c012 T pg_finfo_libafd_traj_quality

Any help is highly appreciated

Answer 1

I think the problem might be that you're telling gdb to debug the shared library, where normally you give it the name of an exectuable. But since you're debugging an already-running process, you shouldn't even have to do that. Try attaching to the process w/o specifying a file, just the PID.