gdb远程调试gdbserver挂起的程序

1. 前言
2. 连接
3. 连接
4. 案例

前言

什么时候需要有gdbserver?

远程调试生产环境; 生产环境没有调试环境, 本地才有;
大佬远程调试有编译环境的环境; 不过这种很少;
被调试程序执行环境不支持gdb的特性; 或者环境不允许, 比如生产环境不好复现环境;

gdbserver能执行的一般也可以执行gdb, 一般都是操作系统, 只是不方便搭建环境而已, 或者不支持全部gdb特性;

C/S模式; 环境复现;

gdb需要复现gdbserver所在的执行环境; 也就是说需要一模一样; exe和其依赖的共享库都需要本地存在, 一模一样, 即ldd查看并打包下载;
为什么需要一模一样? 共享库地址空间等都需要一样? 不然地址空间有差异;

传输协议

有线串口和网络tcp/ip; 明文协议, 不建议上公网;

连接

简介

怎么连: 连接类型和类型之间的差异;
调试环境搭建: 符号信息,源代码,可执行文件,共享库, 连接和断开的指令;

连接类型

target remote ; target extended-remote两种; 一种是普通版; 一种是加强版; 加强版略, 仅介绍普通版本;

指令; extended-remote类型可自行查看;

• 指定调试程序: gdb /path/to/file | gdb -ex 'file /path/to/file', 需要和gdbserver一致,且一般是带符号的;gdbserver connect_addr file | gdbserver connect_addr --attach pid;
• 程序和正在执行的差异: gdb不支持attach, gdbserver支持选中; gdbserver CA file第一条指令暂停; gdbserver CA --attach pid可中止并加断点;
• 连接: gdb执行target remote connect_addr; connect_addr对应gdbserver connect_addr ...中的connect_addr监听端口;
• 执行: run普通模式不支持;
• 退出: gdb exit之后gdbserver一起死亡;while 1会被杀死; 具体什么信号杀死的, 可自行测试;

连接

• 串口: target remote /dev/ttyb

• Unix域: target remote /tmp/gdb-socket0

• TCP

target remote host:port
target remote [host]:port
target remote tcp:host:port
target remote tcp:[host]:port
target remote tcp4:host:port
target remote tcp6:host:port
target remote tcp6:[host]:port

• udp

target remote udp:host:port
target remote udp:[host]:port
target remote udp4:host:port
target remote udp6:[host]:port

• IO: target remote | command, command的输出作为gdb输入, gdb的输出作为command的输入;

案例

• GDB

ch@vm:~/code/cfile/gdbserver$ ls
test.cpp
ch@vm:~/code/cfile/gdbserver$ cat test.cpp 
int main() {
   while(1);
}ch@vm:~/code/cfile/gdbserver$ 
ch@vm:~/code/cfile/gdbserver$ g++ test.cpp -g
ch@vm:~/code/cfile/gdbserver$ scp a.out 192.168.1.20:/home/ch/ch/cfile/test
a.out                                                                  100% 9032     3.5MB/s   00:00    
ch@vm:~/code/cfile/gdbserver$ gdb -q a.out
Reading symbols from a.out...done.
(gdb) target remote 192.168.1.20:8080
Remote debugging using 192.168.1.20:8080
warning: while parsing target description (at line 68): Vector "v8bf16" references undefined type "bfloat16"
warning: Could not load XML target description; ignoring
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
Reading symbols from target:/lib64/ld-linux-x86-64.so.2...Reading /lib64/ef896a699bb1c2e4e231642b2e1688b2f1a61e.debug from remote target...
Reading /lib64/.debug/ef896a699bb1c2e4e231642b2e1688b2f1a61e.debug from remote target...
(no debugging symbols found)...done.
0x00007ffff7fe32b0 in ?? () from target:/lib64/ld-linux-x86-64.so.2
(gdb) b main
Breakpoint 1 at 0x5555554005fe: file test.cpp, line 2.
(gdb) c
Continuing.
Reading /lib/x86_64-linux-gnu/libc.so.6 from remote target...
BFD: warning: target:/lib/x86_64-linux-gnu/libc.so.6: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0008002
Reading /lib/x86_64-linux-gnu/389d485a9793dbe873f0ea2c93e02efaa9aa3d.debug from remote target...
Reading /lib/x86_64-linux-gnu/.debug/389d485a9793dbe873f0ea2c93e02efaa9aa3d.debug from remote target...

Breakpoint 1, main () at test.cpp:2
2           while(1);
(gdb) q
A debugging session is active.

       Inferior 1 [process 211830] will be killed.

Quit anyway? (y or n) y
ch@vm:~/code/cfile/gdbserver$

• gdbserver

ch@ch:~/ch/cfile/test$ ls
ch@ch:~/ch/cfile/test$ pwd
/home/ch/ch/cfile/test
ch@ch:~/ch/cfile/test$ gdbserver 0:8080 a.out 
Process /home/ch/ch/cfile/test/a.out created; pid = 211830
Listening on port 8080
Remote debugging from host 192.168.1.74, port 53562
ch@ch:~/ch/cfile/test$ 

可以看到是一次性连接;