linux - gdb远程内核调试添加bug

Question

我正在使用两个虚拟机(主机和目标)调试 linux-kernel。通过串口连接/dev/ttyS0 .

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HOST
命令行以--> <--高亮显示

--> root@tony-VirtualBox:~/linux# gdb ./vmlinux <--

GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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and "show warranty" for details.
This GDB was configured as "i686-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
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For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./vmlinux...done.

--> (gdb) target remote /dev/ttyS0 <--

Remote debugging using /dev/ttyS0
0xc1119026 in free_rp_inst (rp=<optimized out>)
    at kernel/kprobes.c:1248
1248            kfree(ri);
(gdb) break htb_dequeue_tree
Breakpoint 1 at 0xc17165a9: file net/sched/sch_htb.c, line 850.
(gdb) continue
continuing.

从这一点开始，我连接到目标机器，我在感兴趣的点插入断点，然后 continue启动它的目标机器。当我到达该断点时，控制将返回(HTB 是一个帮助控制给定链接上出站带宽使用的模块)。

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目标

使用 iperf测试 linux htb

tc qdisc add dev eno2 root handle 1: htb 
tc class add dev eth0 parent 1: classid 1:1 htb rate 100kbps ceil 100kbps
tc class add dev eno2 parent 1:1 classid 1:10 htb rate 30kbps ceil 100kbps
tc class add dev eno2 parent 1:1 classid 1:20 htb rate 10kbps ceil 100kbps
tc filter add dev eno2 protocol ip parent 1:0 prio 1 u32 match ip dport 80 0xffff flowid 1:10
tc filter add dev eno2 protocol ip parent 1:0 prio 1 u32 match ip dport 25 0xffff flowid 1:20

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问题

当我启动服务器并连接到它时，为了到达该断点，我收到了 SIGILL在达到该断点之前。没有 Debug模式，它可以完美运行。而且我能够测试 HTB 并得到我期望的结果(按照我的预期方式调整流量)。

[New Thread -2]

Program received signal SIGILL, Illegal instruction.
[Switching to Thread -2]
0xc17165a8 in ffz (word=3889660160)
    at ./arch/x86/include/asm/bitops.h:381
381                    : "r" (~word));

(gdb)

它可能是什么？这里是ffz已定义，它不应该崩溃......我很困惑。

Answer 1

尝试添加 rodata=off 和 nokaslr 内核引导参数。

这里是添加内核启动参数的方法: https://askubuntu.com/questions/19486/how-do-i-add-a-kernel-boot-parameter