ubuntu kgdb kernel 调试环境搭建

ubuntu kgdb kernel 调试环境搭建

2012-01-02 19:38 82人阅读 评论(0) 举报

调试环境(末尾还有ubuntu下vmware的环境搭建方法)：

主机：WindowsXP Professional 5.1.2600, Service Pack 3

Vmware：VMware®Workstation 7.1.3 build-324285

Ubuntu: ubuntu 10.04

1. 在vmware中建立一个ubuntu的虚拟机，命名为FS_client.

root@huerjia:/home/huerjia#uname -a

Linuxhuerjia 2.6.34.1 #4 SMP Mon Dec 26 22:16:52 CST 2011 i686 GNU/Linux

下载的linux代码为：linux-2.6.34.1.tar.bz2

解压在/home/huerjia/linux/linux-2.6.34.1中，

开始编译内核：

内核版本比较近，我们可以先

cp/boot/config-2.6.32-28-generic/home/huerjia/linux/linux-2.6.34.1/.config

再

Make menuconfig：

Load.config

注意下面几个选项配置：

主要是保证内核启动模块可动态加载的配置

Loadablemodule support ----->

保持默认状态

KernelHacking -->

选中Compilethe kernel with debug info
     选中Compilethe kernel with frame pointers
     选中KGDB:kerneldebugging with remote gdb

其中，KGDB:kerneldebugging with remote gdb下全部选上。

也有几项需要去掉：

Processortype and features中去掉Paravirtualizedguest support

KernelHacking中去掉Writeprotect kernel read-only data structures（否则不能用软件断点）

记得文件系统的ext2、ext3和ext4都选上。

保存.config文件

接着

Make

MakebzImage

Makemodules

Makemodules_install

Makeinstall

可以在/boot目下看到生成的System.map-2.6.34.1和vmlinuz-2.6.34.1

使用mkinitramfs-kpkg生initrd.img-2.6.34.1

2. 使用vmware的clone功能新建一个ubuntu虚拟机，命名为FS_server。

在client端添加串口，类型选Use named pipe：

Thisend is the client

Theother end is a virtual machine

在server端添加抽口，功能选Usenamed pipe：

Thisend is the server

Theother end is a virtual machine

将生成的System.map vmlinuz和 initrd.img拷贝到/boot下，重新命名为

System.map-2.6.34.1-kgdb

vmlinuz-2.6.34.1-kgdb

initrd.img-2.6.34.1-kgdb

运行update-grub

接下来修改

gvim/etc/default/grub

gvim/boot/grub/grub.cfg

/etc/default/grub修改如下：

GRUB_DEFAULT=0 //设定默认启动项

#GRUB_HIDDEN_TIMEOUT=30 //注释掉这行会显示引导菜单

GRUB_HIDDEN_TIMEOUT_QUIET=false //如果为true，黑屏且不会显示倒计时

GRUB_TIMEOUT=30 //倒计时

GRUB_DISTRIBUTOR=`lsb_release -i-s 2> /dev/null || echo Debian`

GRUB_CMDLINE_LINUX_DEFAULT="rootdelay=90quiet splash text" //text表示命令行方式启动

GRUB_CMDLINE_LINUX=""

/boot/grub/grub.cfg修改如下：

### BEGIN /etc/grub.d/10_linux###

menuentry 'Ubuntu, with Linux2.6.34.1-kgdb' --class ubuntu --class gnu-linux --class gnu --classos {

recordfail

insmod ext2

set root='(hd0,1)'

search --no-floppy --fs-uuid--set 78727361-022c-4790-8d39-a17565a4e155

linux /boot/vmlinuz-2.6.34.1-kgdbroot=UUID=78727361-022c-4790-8d39-a17565a4e155 ro rootdelay=90quiet splash text kgdboc=ttyS1,115200 vga=14745600

initrd /boot/initrd.img-2.6.34.1-kgdb

}

注意加上kgdboc=ttyS1,115200，kgdbwait不加感觉更好用。

vga=14745600是想让命令行的窗口变大，但是没有效果。有人说装zhcon，改天试下。

FS_server选择kgdb启动，

登录后echog > /proc/sysrq-trigger 开启kgdb

Server上显示：

SysRq：DEBUG

Entering KGDB

这时候，在client端：

Gdbvmlinux

huerjia@huerjia:~/linux/linux-2.6.34.1$gdb vmlinux

GNU gdb (GDB) 7.1-ubuntu

Copyright (C) 2010 Free SoftwareFoundation, Inc.

License GPLv3+: GNU GPL version3 or later <

This is free software: you arefree to change and redistribute it.

There is NO WARRANTY, to theextent 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:

<

Reading symbols from/home/huerjia/linux/linux-2.6.34.1/vmlinux...done.

(gdb) set remotebaud 115200

(gdb) target remote /dev/ttyS1

Remote debugging using/dev/ttyS1

kgdb_breakpoint (key=, tty=)

at kernel/kgdb.c:1749

1749 wmb(); /* Sync point afterbreakpoint */

(gdb) l sys_init_module

2497 }

2498

2499 /* This is where the realwork happens */

2500 SYSCALL_DEFINE3(init_module,void __user *, umod,

2501 unsigned long, len, constchar __user *, uargs)

2502 {

2503 struct module *mod;

2504 int ret = 0;

2505

2506 /* Must have permission */

(gdb)

2507 if(!capable(CAP_SYS_MODULE) || modules_disabled)

2508 return -EPERM;

2509

2510 /* Only one module load ata time, please */

2511 if(mutex_lock_interruptible(&module_mutex) != 0)

2512 return -EINTR;

2513

2514 /* Do all the hard work */

2515 mod = load_module(umod,len, uargs);

2516 if (IS_ERR(mod)) {

(gdb) b 2515

Breakpoint1 at 0xc017c44d: file kernel/module.c, line 2515.

(gdb) c

Continuing.

此时在server端insmod cramfs.ko

Client端显示：

[NewThread 1660]

[Switchingto Thread 1660]

Breakpoint1, sys_init_module (umod=0xb769b008, len=168199, uargs=0x9ad5008 "")

atkernel/module.c:2515

2515 mod= load_module(umod, len, uargs);

(gdb) p *mod

Cannot access memory at address0x0

(gdb) n

2516 if (IS_ERR(mod)) {

(gdb) p *mod

Cannot access memory at address0x0

(gdb) n

2515 mod = load_module(umod,len, uargs);

(gdb) p *mod

$1 = {state =MODULE_STATE_COMING, list = {next = 0xe2582264,

prev = 0xc0775a14}, name ="cramfs", '\000' , mkobj = {

kobj = {name = 0xdd6f2428"cramfs", entry = {next = 0xdf880100,

prev = 0xe25822ac},parent = 0xdf88010c, kset = 0xdf880100,

ktype = 0xc0775240, sd =0xdccd6630, 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 = 0xe25cc360,

drivers_dir = 0x0, mp =0x0}, modinfo_attrs = 0xde740540, version = 0x0,

srcversion = 0xdd175100"DFAAD48F3B1015295C8631C", holders_dir = 0xdd5e1980,

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 =0xe25d7000, module_init = 0xe25d7000,

module_core = 0xe25cb000,init_size = 3071, core_size = 39266,

init_text_size = 42,core_text_size = 4040, arch = {},

taints = 0, num_bugs = 0,bug_list = {next = 0xe2582358, prev = 0xc0788460},

bug_table = 0x0, symtab =0xe25d702c, core_symtab = 0xe25d4554,

num_symtab = 111,core_num_syms = 33, strtab = 0xe25d771c "",

core_strtab = 0xe25d4764 "",sect_attrs = 0xdd119800,

notes_attrs = 0xdccde3c0,percpu = 0x0, percpu_size = 0,

args = 0xdd6f2418 "",tracepoints = 0x0, num_tracepoints = 0,

---Type tocontinue, or q to quit---

(gdb) p*(mod->sect_attrs->attrs+1)

$2 = {mattr = {attr = {name =0xde6d5828 ".text", owner = 0x0, mode = 292},

show = 0xc0179670, store = 0, setup = 0, test = 0,

free = 0}, name = 0xde6d5828".text", address = 3797725184}

(gdb) p*(mod->sect_attrs->attrs+2)

$3 = {mattr = {attr = {name =0xde653800 ".exit.text", owner = 0x0,

mode = 292}, show =0xc0179670 , store = 0, setup = 0,

test = 0, free = 0}, name =0xde653800 ".exit.text", address = 3797729196}

(gdb) p*(mod->sect_attrs->attrs+3)

$4 = {mattr = {attr = {name =0xdd1cae40 ".altinstr_replacement", owner = 0x0,

mode = 292}, show =0xc0179670 , store = 0, setup = 0,

test = 0, free = 0}, name =0xdd1cae40 ".altinstr_replacement",

address = 3797729221}

(gdb) p*(mod->sect_attrs->attrs+4)

$5 = {mattr = {attr = {name =0xde6537f0 ".init.text", owner = 0x0,

mode = 292}, show =0xc0179670 , store = 0, setup = 0,

test = 0, free = 0}, name =0xde6537f0 ".init.text", address = 3797774336}

(gdb) add-symbol-file/home/huerjia/linux/linux-2.6.34.1/fs/cramfs/cramfs.ko 3797725184 -s.exit.text 3797729196 -s .init.text 3797774336

add symbol table from file"/home/huerjia/linux/linux-2.6.34.1/fs/cramfs/cramfs.ko" at

.text_addr = 0xe25cb000

.exit.text_addr = 0xe25cbfac

.init.text_addr = 0xe25d7000

(y or n) y

Reading symbols from/home/huerjia/linux/linux-2.6.34.1/fs/cramfs/cramfs.ko...done.

(gdb) b cramfs

cramfs.mod.c cramfs_ops

cramfs_aops cramfs_put_super

cramfs_dir_inode_operations cramfs_read

cramfs_directory_operations cramfs_readdir

cramfs_drop_inode cramfs_readpage

cramfs_fill_super cramfs_remount

cramfs_fs_type cramfs_sb_info

cramfs_get_sb cramfs_statfs

cramfs_iget5_set cramfs_super

cramfs_iget5_test cramfs_uncompress_block

cramfs_info cramfs_uncompress_exit

cramfs_inode cramfs_uncompress_init

cramfs_lookup

(gdb) b init_cramfs_fs

Breakpoint 3 at 0xe26f7006: filefs/cramfs/inode.c, line 567.

(gdb) c

Continuing.

Breakpoint 3, init_cramfs_fs ()at fs/cramfs/inode.c:567

567 rv =cramfs_uncompress_init();

(gdb)

这样就可以从模块初始化开始debug模块了。后续对filesystem的学习就打通了途径。

如果主机是linux，那就只需要建立一个虚拟机

1. 新建一个虚拟机，增加一个串口，让串口指向命名管道/tmp/com_1
   2)虚拟机安装Linux的一个发布版，推荐Fedora，因为我用ubuntu没有成功，^_^。
   3)安装Fedora时不需要安装桌面，但开发库和开发工具要安装，如果你想在虚拟机上编
   译内核

虚拟机的串口设置：

vmware： 添加虚拟串口，在use socket（named pipe）里面填入 /tmp/serial，其他选this is server，other is an application

三，创建配置文件
1)复制虚拟机Linux的配置文件到要调试内核的源代码目录
2）修改配置文件，（我用的是makemenuconfig）
   1，进入KernelHacking
    2, 选中MagicSysrq Key
    3, 选中Compilethe kernel with debug info
    4，选中KGDB:kernel debugging with remote gdb

四，使用修改后的配置文件编译内核，并在虚拟机上安装编译好的内核。简单来说，就是:
1)make
2) make modules_install
3) make install
请参考

五，配置目标机（虚拟机）
1)编辑/etc/sysctl.conf,设置kernel.sysrq=1
2)修改/boot/grub/grub.conf，为新安装的内核增加引导参数。比如我的是：
   kernel /vmlinuz-2.6.28 ro root=/dev/XXX kgdboc=ttyS1,115200kgdbwait
   关键是kgdboc后面的。这种设置会使内核在加载kgdb模块后，立即等待远程gdb接入，
   如果想在用户登录以后再调试，就不需要这种设置。

六，如果内核是在虚拟机上编译的，那么将编译后的vmlinuz和System.map下载到开发机
内核代码目录

七，重启虚拟机，进入新安装的内核，如果要求gdb接入，则内核会自动挂起，并输出提
示信息：kgdb:Waiting for connection from remote gdb...

八，配置开发机（本机Linux）。VMware中串口指向的命名管道并不是真实的命名管道，
而是一个Unix-domain的socket，但是gdb不能使用这种socket，所以需要把它重定向到
gdb能够支持的设备：
   $ socat -d -d /tmp/com_1 PTY，输出结果会告诉你定向到了哪个设备，如/dev/pts/2

九，开始调试
1)进入内核代码目录
2)$gdb ./vmlinuz
3）$(gdb)setremotebaud 115200
4) $(gdb)target remote/dev/pts/2;当然也有可能不是2，根据实际情况而定
5)如果成功，则会发现虚拟机的断点设在kernel/kgdb.c文件中

十，如果是想在用户登录以后调试，则可以通过以下方法触发kgdb
1）$echottyS0 > /sys/module/kgdboc/parameters/kgdboc
2) $echo "g"> /proc/sysrq-trigger，再次触发