Question

我现在正在使用Linux跟踪点进行练习。基本上，我正在尝试制作一个内核模块，在其中定义了探测功能并将其连接到Linux内核中的tracepoint（内核源文件dev.c中的tracepoint（“ trace_netif_receive_skb”））。当我在SLES11上编译并运行内核模块时，它运行良好。但是，当我在SLES12上执行相同的操作时，它抱怨该符号未定义。内核模块源代码为：

  1 #include <linux/module.h>
  2 #include <linux/kernel.h>
  3 #include <linux/init.h>
  4 #include <linux/skbuff.h>
  5 #include <trace/events/net.h>
  6 
  7 static void probe(void *ignore, struct sk_buff *skb)
  8 {
  9     printk(KERN_INFO "probe, protocol[0X%04X]\n", ntohs(skb->protocol));
 10 }
 11 
 12 static int __init init_tracepoint(void)
 13 {
 14     if (0 != register_trace_netif_receive_skb(probe, NULL))
 15     {
 16         printk(KERN_INFO "tracepoint init fails\n");
 17     }
 18 
 19     printk(KERN_INFO "tracepoint init succeeds\n");
 20     return 0;
 21 }
 22 
 23 static void __exit cleanup_tracepoint(void)
 24 {
 25     unregister_trace_netif_receive_skb(probe, NULL);
 26     tracepoint_synchronize_unregister();
 27 
 28     printk(KERN_INFO "tracepoint exit\n");
 29 }
 30 
 31 module_init(init_tracepoint);
 32 module_exit(cleanup_tracepoint);
 33 
 34 MODULE_LICENSE("GPL");

这是SLES11的输出，未报告任何错误。

suse11-1:~/works/tracepoint # make
make -C /lib/modules/3.0.76-0.11-default/build M=/root/works/tracepoint modules
make[1]: Entering directory `/usr/src/linux-3.0.76-0.11-obj/x86_64/default'
make -C ../../../linux-3.0.76-0.11 O=/usr/src/linux-3.0.76-0.11-obj/x86_64/default/. modules
  CC [M]  /root/works/tracepoint/tracepoint.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /root/works/tracepoint/tracepoint.mod.o
  LD [M]  /root/works/tracepoint/tracepoint.ko
make[1]: Leaving directory `/usr/src/linux-3.0.76-0.11-obj/x86_64/default'
suse11-1:~/works/tracepoint # insmod tracepoint.ko

这是SLES12的输出，它说：警告：“ __ tracepoint_netif_receive_skb” [/ root / works / codes / tracepoint / tracepoint.ko]未定义！在/ var / log / messages中可以找到“未知符号__tracepoint_netif_receive_skb（err 0）”。

suse12-1:~/works/codes/tracepoint # make
make -C /lib/modules/4.4.21-69-default/build M=/root/works/codes/tracepoint modules
make[1]: Entering directory '/usr/src/linux-4.4.21-69-obj/x86_64/default'
  CC [M]  /root/works/codes/tracepoint/tracepoint.o
  Building modules, stage 2.
  MODPOST 1 modules
WARNING: "__tracepoint_netif_receive_skb" [/root/works/codes/tracepoint/tracepoint.ko] undefined!
  CC      /root/works/codes/tracepoint/tracepoint.mod.o
  LD [M]  /root/works/codes/tracepoint/tracepoint.ko
make[1]: Leaving directory '/usr/src/linux-4.4.21-69-obj/x86_64/default'
suse12-1:~/works/codes/tracepoint # 
suse12-1:~/works/codes/tracepoint # insmod tracepoint.ko 
insmod: ERROR: could not insert module tracepoint.ko: Unknown symbol in module

我检查了SLES11和SLES12的跟踪点框架的内核源代码，除非调用EXPORT_TRACEPOINT_SYMBOL（）或EXPORT_TRACEPOINT_SYMBOL_GPL（），否则不会导出定义为“ include / linux / tracepoint.h”的“ __tracepoint _ ## name”，但是，但是我没有在Linux内核代码中找到调用EXPORT_TRACEPOINT_SYMBOL（netif_receive_skb）或EXPORT_TRACEPOINT_SYMBOL_GPL（netif_receive_skb）来导出符号__tracepoint_netif_receive_skb的任何地方。那为什么我在SLES11上遇到问题呢？我如何在SLES12上使用它？

Linux内核跟踪点：将探测函数连接到跟踪点时，符号未定义

0 个答案: