内核模块找不到调试符号 [英] kernel module no debugging symbols found

问题描述

在加载linux内核模块后，使用

  user @ c4：$ insmod mmaptest.ko 
  

我可以验证它是通过

  user @ c4：$ cat / proc / modules 
 mmaptest 12727 0  -  Live 0x0000000000000000（OF）
  

，但所有段均以0x00地址列出。

  user @ c4 $：$ systool -vm mmaptest 
 Module =mmaptest
 
属性：
 coresize =12727
 initsize =0
 initstate =live
 refcnt =0
 srcversion =EABEF6F90BEAAD0D15B576A
 taint =OF
 uevent =<仅存储方法> 
 
参数：
 count =0
 
部分：
 .bss =0x0000000000000000
 .data =0x0000000000000000
 .exit.text =0x0000000000000000
 .gnu.linkonce.this_module =0x0000000000000000
 .init.text =0x0000000000000000
 .note.gnu.build-id = 0x0000000000000000
 .rodata =0x0000000000000000
 .rodata.str1.1 =0x0000000000000000
 .rodata.str1.8 =0x0000000000000000
 .smp_locks =0x0000000000000000 
 .strtab =0x0000000000000000
 .symtab =0x0000000000000000
 .text =0x0000000000000000
 __mcount_loc =0x0000000000000000
 __param =0x0000000000000000$因此，当我尝试从不正确的（？）地址的模块文本段中加载符号时，我得到： 

p>



 （gdb）add-symbol-file /home/mmaptest/mmaptest.ko 0x00 
从文件中添加符号表/ home / mmaptest / mmaptest .ko在
 .text_addr = 0x0 
（y或n）y 
读取/home/mmaptest/mmaptest.ko...中的符号（没有找到调试符号**） ...完成。 
  

这是关于模块本身还是加载到内核代码中的情况？为什么所有地址都是0x000000000000？

解决方案

我的标记不正确。调试符号表是用这个makefile构建的：



  obj -m + = mmaptest.o 
 MY_CFLAGS + = -g -DDEBUG 
 ccflags-y + = $ {MY_CFLAGS} 
 CC + = $ {MY_CFLAGS} 
 
 
全部：
 make -C / lib / modules / $（shell uname -r）/ build M = $（PWD）模块
 
 debug：
 make -C / lib / modules / $（shell uname -r）/ build M = $（PWD）模块
 EXTRA_CFLAGS =$（MY_CFLAGS）
 clean：make -C / lib / modules / $（shell uname -r）/ build M = $（PWD）clean 
  

现在可以验证：



  peter @ c4：$ readelf -S mmaptest.ko | grep debug 
 $ b $ [24] .debug_info PROGBITS 0000000000000000 00000d40 
 [25] .rela.debug_info RELA 0000000000000000 00018260 
 [26] .debug_abbrev PROGBITS 0000000000000000 0000d577 
 [27 ] .debug_loc PROGBITS 0000000000000000 0000dd54 
 [28] .rela.debug_loc RELA 0000000000000000 00029510 
 [29] .debug_aranges PROGBITS 0000000000000000 0000e5d5 
 [30] .rela.debug_arang RELA 0000000000000000 0002a3e0 
 [31] .debug_ranges PROGBITS 0000000000000000 0000e645 
 [32] .rela.debug_range RELA 0000000000000000 0002a458 
 [33] .debug_line PROGBITS 0000000000000000 0000e815 
 [34] .rela.debug_line RELA 0000000000000000 0002a878 
 [35] .debug_str PROGBITS 0000000000000000 0000f4cd 
 [38] .debug_frame PROGBITS 0000000000000000 00016e80 
 [39] .rela.deb ug_frame RELA 0000000000000000 0002a8c0 
 
 
 
从文件/home/peter/projects/svn/linux_kernel/mmaptest/mmaptest.ko添加符号表
 at .text_addr = 0x0 
（y或n）y 
读取/home/peter/projects/svn/linux_kernel/mmaptest/mmaptest.ko...done中的符号。 
（gdb）
  




After I loaded linux kernel module with

user@c4:$ insmod mmaptest.ko

I can verify that it is loaded via

user@c4:$ cat /proc/modules 
mmaptest 12727 0 - Live 0x0000000000000000 (OF)

but all segments are listed with 0x00 addresses.

user@c4$:$ systool -vm mmaptest
  Module = "mmaptest"

  Attributes:
    coresize            = "12727"
    initsize            = "0"
    initstate           = "live"
    refcnt              = "0"
    srcversion          = "EABEF6F90BEAAD0D15B576A"
    taint               = "OF"
    uevent              = <store method only>

  Parameters:
    count               = "0"

  Sections:
    .bss                = "0x0000000000000000"
    .data               = "0x0000000000000000"
    .exit.text          = "0x0000000000000000"
    .gnu.linkonce.this_module= "0x0000000000000000"
    .init.text          = "0x0000000000000000"
    .note.gnu.build-id  = "0x0000000000000000"
    .rodata             = "0x0000000000000000"
    .rodata.str1.1      = "0x0000000000000000"
    .rodata.str1.8      = "0x0000000000000000"
    .smp_locks          = "0x0000000000000000"
    .strtab             = "0x0000000000000000"
    .symtab             = "0x0000000000000000"
    .text               = "0x0000000000000000"
    __mcount_loc        = "0x0000000000000000"
    __param             = "0x0000000000000000"

Thus when I try to load symbols from module text segment at incorrect (?) addresses I get:

(gdb) add-symbol-file /home/mmaptest/mmaptest.ko 0x00
add symbol table from file "/home/mmaptest/mmaptest.ko" at
    .text_addr = 0x0
(y or n) y
Reading symbols from /home/mmaptest/mmaptest.ko...(**no debugging symbols found**)...done.

Is this the case about module itself or loading into kernel code? Why all addresses are 0x000000000000?

解决方案

My flags were incorrect. Debugging symbol table is built with this makefile:

obj-m += mmaptest.o
MY_CFLAGS += -g -DDEBUG
ccflags-y += ${MY_CFLAGS}
CC += ${MY_CFLAGS}


all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

debug:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules 
        EXTRA_CFLAGS="$(MY_CFLAGS)"
clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean 

This can be verified now with:

peter@c4:$ readelf -S mmaptest.ko | grep debug

  [24] .debug_info       PROGBITS         0000000000000000  00000d40
  [25] .rela.debug_info  RELA             0000000000000000  00018260
  [26] .debug_abbrev     PROGBITS         0000000000000000  0000d577
  [27] .debug_loc        PROGBITS         0000000000000000  0000dd54
  [28] .rela.debug_loc   RELA             0000000000000000  00029510
  [29] .debug_aranges    PROGBITS         0000000000000000  0000e5d5
  [30] .rela.debug_arang RELA             0000000000000000  0002a3e0
  [31] .debug_ranges     PROGBITS         0000000000000000  0000e645
  [32] .rela.debug_range RELA             0000000000000000  0002a458
  [33] .debug_line       PROGBITS         0000000000000000  0000e815
  [34] .rela.debug_line  RELA             0000000000000000  0002a878
  [35] .debug_str        PROGBITS         0000000000000000  0000f4cd
  [38] .debug_frame      PROGBITS         0000000000000000  00016e80
  [39] .rela.debug_frame RELA             0000000000000000  0002a8c0



add symbol table from file "/home/peter/projects/svn/linux_kernel/mmaptest/mmaptest.ko"
at .text_addr = 0x0
(y or n) y
Reading symbols from /home/peter/projects/svn/linux_kernel/mmaptest/mmaptest.ko...done.
(gdb) 

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