Hello all,
I got another problem while I'm trying to debug mine kernel module. Here
is procedure that I perform while setting up debug session and results.
First run the UML kernel with:
dzwiedz ~/projekty/uml_debug/linux-2.6.32.19 [3387] ./linux
ubda=../debian_uml ubdc=../swap mem=128M con0=fd:0,fd:1 con=pts
Locating the bottom of the address space ... 0x10000
[....kernel is booting....]
Last login: Wed Sep 1 10:55:00 UTC 2010 on tty0
Linux uml 2.6.32.19 #3 Thu Aug 26 13:56:25 CEST 2010 i686
The programs included with the Debian GNU/Linux system are free
software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
uml:~#
Then run gdb and attach it to UML process:
dzwiedz ~/projekty/uml_debug/linux-2.6.32.19 [3362] gdb ./linux
32764 13:21
GNU gdb (GDB) 7.1-ubuntu
Copyright (C) 2010 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 "i486-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from
/home/dzwiedz/projekty/uml_debug/linux-2.6.32.19/linux...done.
Attaching to program:
/home/dzwiedz/projekty/uml_debug/linux-2.6.32.19/linux, process 32764
Reading symbols from /lib/tls/i686/cmov/libutil.so.1...(no debugging
symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libutil.so.1
Reading symbols from /lib/tls/i686/cmov/libc.so.6...(no debugging
symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libc.so.6
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols
found)...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_compat.so.2...(no
debugging symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_compat.so.2
Reading symbols from /lib/tls/i686/cmov/libnsl.so.1...(no debugging
symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libnsl.so.1
Reading symbols from /lib/tls/i686/cmov/libnss_nis.so.2...(no
debugging symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_nis.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_files.so.2...(no
debugging symbols found)...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_files.so.2
0x00835422 in __kernel_vsyscall ()
Check existing breakpoints and then, setup handlers for signals and
breakpoint at line with mod->init (kernel/module.c)
(gdb) info break
No breakpoints or watchpoints.
(gdb) b module.c:2613
No line 2613 in file "drivers/base/module.c".
(gdb) b sys_module_init
Function "sys_module_init" not defined.
Make breakpoint pending on future shared library load? (y or [n]) n
(gdb) b sys_init_module
Breakpoint 1 at 0x80945a6: file kernel/module.c, line 2591.
(gdb) b module.c:2613
Breakpoint 2 at 0x809461b: file kernel/module.c, line 2613.
(gdb) handle SIGSEGV pass noprint nostop
Signal Stop Print Pass to program Description
SIGSEGV No No Yes Segmentation fault
(gdb) handle SIGUSR1 pass noprint nostop
Signal Stop Print Pass to program Description
SIGUSR1 No No Yes User defined signal 1
(gdb) info b
Num Type Disp Enb Address What
1 breakpoint keep y 0x080945a6 in sys_init_module
at kernel/module.c:2591
2 breakpoint keep y 0x0809461b in sys_init_module
at kernel/module.c:2613
(gdb) c
Continuing.
Then insmod my module with insmod mapper_test.ko. After reaching second
breakpoint I check module list for memory address of mapper_test module
as described in tutorial on UML home page. Then I set breakpoints for
interesting init and cleanup function. Which are properly recognized and
found by GDB with print command. But when I try to continue to reach
this new breakpoints then I got errors. Below is whole listing.
Breakpoint 1, sys_init_module (umod=0x804b018, len=50866,
uargs=0x804b008 "\377P\211\303\350ג\001") at kernel/module.c:2591
2591 if (!capable(CAP_SYS_MODULE) || modules_disabled)
(gdb) c
Continuing.
Breakpoint 2, sys_init_module (umod=0x804b018, len=50866,
uargs=0x804b008 "\377P\211\303\350ג\001") at kernel/module.c:2613
2613 if (mod->init != NULL)
(gdb) p modules
$1 = {next = 0x1256d7f0, prev = 0x125478dc}
(gdb) p 0x1256d7ec
$2 = 307681260
(gdb) p *((struct module *)0x1256d7ec)
$3 = {state = MODULE_STATE_COMING, list = {next = 0x125478dc,
prev = 0x8236ab0}, name = "mapper_test", '\000' <repeats 48
times>,
mkobj = {kobj = {name = 0x10ac26e0 "mapper_test", entry = {
next = 0x118499a0, prev = 0x12547924}, parent = 0x118499b8,
kset = 0x118499a0, ktype = 0x82363c8, sd = 0x11a22198, kref = {
refcount = {counter = 3}}, state_initialized = 1,
state_in_sysfs = 1,
state_add_uevent_sent = 1, state_remove_uevent_sent = 0,
uevent_suppress = 0}, mod = 0x1256d7ec, drivers_dir = 0x0, mp
= 0x0},
modinfo_attrs = 0x11a062e0, version = 0x0, srcversion = 0x0,
holders_dir = 0x119abd60, syms = 0x0, crcs = 0x0, num_syms = 0,
kp = 0x0,
num_kp = 0, num_gpl_syms = 0, gpl_syms = 0x0, gpl_crcs = 0x0,
unused_syms = 0x0, unused_crcs = 0x0, num_unused_syms = 0,
num_unused_gpl_syms = 0, unused_gpl_syms = 0x0, unused_gpl_crcs =
0x0,
gpl_future_syms = 0x0, gpl_future_crcs = 0x0, num_gpl_future_syms
= 0,
num_exentries = 0, extable = 0x0, init = 0x1256d00a,
module_init = 0x12570000, module_core = 0x1256d000, init_size =
2322,
core_size = 3353, init_text_size = 421, core_text_size = 1039,
arch = {<No data fields>}, taints = 0, num_bugs = 0, bug_list = {
next = 0x125479d0, prev = 0x823a118}, bug_table = 0x0,
symtab = 0x125701a8, core_symtab = 0x1256da74, num_symtab = 70,
core_num_syms = 19, strtab = 0x12570608 "", core_strtab =
0x1256dba4 "",
sect_attrs = 0x10ac4200, notes_attrs = 0x119abd20, percpu = 0x0,
args = 0x10ac2880 "", modules_which_use_me = {next = 0x1256d918,
prev = 0x1256d918}, waiter = 0x11874060, exit = 0x1256d000, ref
= {a = {
counter = 1}}}
(gdb) add-symbol-file /home/dzwiedz/projekty/BIS/mapper_test.ko
0x1256d000
add symbol table from file
"/home/dzwiedz/projekty/BIS/mapper_test.ko" at
.text_addr = 0x1256d000
(y or n) y
Reading symbols from /home/dzwiedz/projekty/BIS/mapper_test.ko...done.
(gdb) p nf_mapper_init
$7 = {int (void)} 0x274 <nf_mapper_init>
(gdb) p nf_mapper_cleanup
$8 = {void (void)} 0xa9 <nf_mapper_cleanup>
(gdb) b nf_mapper_init
Breakpoint 3 at 0x274: file
/home/dzwiedz/projekty/BIS/nf_bis_mapper.c, line 48.
(gdb) b nf_mapper_cleanup
Breakpoint 4 at 0xa9: file
/home/dzwiedz/projekty/BIS/nf_bis_mapper.c, line 75.
(gdb) s
Warning:
Cannot insert breakpoint 4.
Error accessing memory address 0xa9: Input/output error.
Cannot insert breakpoint 3.
Error accessing memory address 0x274: Input/output error.
hard_handler (sig=29) at arch/um/os-Linux/sys-i386/signal.c:11
11 {
(gdb)
What am I doing wrong? As anybody could help to make this config working? :)
regards,
--
Paweł R.
<pawel.ru...@wp.pl>
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