从使用ARM-GCC编译的elf文件中提取详细的符号信息(结构成员) [英] Extract detailed symbol information (struct members) from elf file compiled with ARM-GCC
问题描述
我正在使用ARM-GCC 4.7.4编译Cortex-M4的代码.对于我们的调试工具，我需要有关人类可读格式(例如.txt)的所有变量的名称，类型和地址的知识.映射文件提供了大多数信息，但不幸的是，没有提供有关结构内容的信息，如下所示:
I’m using ARM-GCC 4.7.4 to compile Code for a Cortex-M4. For our Debug tool I need knowledge about names, types and addresses of all variables in human readable format (e.g. .txt). The map file provides most of the information, unfortunately not for structure contents like below:
typedef struct { float32_t Ref; // Input: Reference Value
float32_t Fdb; // Variable: Feedback Value
float32_t Err; // Input: Control Error
float32_t Kp; // Parameter: Gain of the Proportional Part
float32_t Up; // Output: Output of Proportional Part
float32_t Ki; // Parameter: Gain of the Integral Part
float32_t Ui; // Output: Output of the Integral Part
float32_t OutPreSat; // Output: Not saturated Output
float32_t OutMax; // Parameter: Maximum Output
float32_t OutMin; // Parameter: Minimum Output
float32_t Out; // Output: Saturated Output
} PI_REG;
PI_REG BU_Uctrl_Udc_PI_Reg = BU_UCTRL_UDC_PI_REG_INIT;
因此，我尝试使用nm，readelf和objdump工具从.elf文件中获取一些内容，该文件使用参数–g3以dwarf-2格式编译.只有使用objdump，我才能找到我搜索的信息:
Therefore I tried the tools nm, readelf and objdump to get something out of the .elf file which is compiled with parameter –g3 in dwarf-2 format. Only with objdump I could find the information I searched for:
objdump –Wi myfile.elf >symbols.txt
有关typedef PI_REG的以下信息可以在symbol.txt文件中找到:
The following information about the typedef PI_REG can be found in symbols.txt file:
<1><38883>: Abbrev Number: 2 (DW_TAG_base_type)
<38884> DW_AT_byte_size : 4
<38885> DW_AT_encoding : 4 (float)
<38886> DW_AT_name : (indirect string, offset: 0x2c63e): float
<1><38891>: Abbrev Number: 11 (DW_TAG_typedef)
<38892> DW_AT_name : (indirect string, offset: 0xb336d): float32_t
<38896> DW_AT_decl_file : 4
<38897> DW_AT_decl_line : 370
<38899> DW_AT_type : <0x38883>
<1><390d7>: Abbrev Number: 14 (DW_TAG_structure_type)
<390d8> DW_AT_byte_size : 44
<390d9> DW_AT_decl_file : 6
<390da> DW_AT_decl_line : 26
<390db> DW_AT_sibling : <0x39176>
<2><390df>: Abbrev Number: 16 (DW_TAG_member)
<390e0> DW_AT_name : Ref
<390e4> DW_AT_decl_file : 6
<390e5> DW_AT_decl_line : 26
<390e6> DW_AT_type : <0x38891>
<390ea> DW_AT_data_member_location: 2 byte block: 23 0 (DW_OP_plus_uconst: 0)
<2><390ed>: Abbrev Number: 16 (DW_TAG_member)
<390ee> DW_AT_name : Fdb
<390f2> DW_AT_decl_file : 6
<390f3> DW_AT_decl_line : 27
<390f4> DW_AT_type : <0x38891>
<390f8> DW_AT_data_member_location: 2 byte block: 23 4 (DW_OP_plus_uconst: 4)
[偏移量为6-32的遗漏结构成员]
[left out structure members with offsets 6-32]
<2><39159>: Abbrev Number: 15 (DW_TAG_member)
<3915a> DW_AT_name : (indirect string, offset: 0xc1d9a): OutMin
<3915e> DW_AT_decl_file : 6
<3915f> DW_AT_decl_line : 35
<39160> DW_AT_type : <0x38891>
<39164> DW_AT_data_member_location: 2 byte block: 23 24 (DW_OP_plus_uconst: 36)
<2><39167>: Abbrev Number: 16 (DW_TAG_member)
<39168> DW_AT_name : Out
<3916c> DW_AT_decl_file : 6
<3916d> DW_AT_decl_line : 36
<3916e> DW_AT_type : <0x38891>
<39172> DW_AT_data_member_location: 2 byte block: 23 28 (DW_OP_plus_uconst: 40)
<1><39176>: Abbrev Number: 3 (DW_TAG_typedef)
<39177> DW_AT_name : (indirect string, offset: 0xc00d0): PI_REG
<3917b> DW_AT_decl_file : 6
<3917c> DW_AT_decl_line : 37
<3917d> DW_AT_type : <0x390d7>
<1><3c348>: Abbrev Number: 29 (DW_TAG_variable)
<3c349> DW_AT_name : (indirect string, offset: 0xc3ece): BU_Uctrl_Udc_PI_Reg
<3c34d> DW_AT_decl_file : 1
<3c34e> DW_AT_decl_line : 40
<3c34f> DW_AT_type : <0x39176>
<3c353> DW_AT_external : 1
<3c354> DW_AT_location : 5 byte block: 3 fc 67 0 20 (DW_OP_addr: 200067fc)
如果我想获取有关变量的信息，例如结构BU_Uctrl_Udc_PI_Reg，我必须执行以下操作:
If I want to get information about variables, e.g. the structure BU_Uctrl_Udc_PI_Reg, I have to do the following:
Find an entry called "DW_TAG_variable" and gather following information:
------------------------------------------------------------------------
- DW_AT_name: The name is BU_Uctrl_Udc_PI_Reg
- DW_OP_addr: Base address is 200067fc
- DW_AT_type: The data type can be found at line 39176
Search line 39176 and gather following information:
-----------------------------------------------------
- It is a typedef (DW_TAG_typedef)
- DW_AT_name: The typedef name is PI_REG
- DW_AT_type: The definition can be found at line 390d7
Search line 390d7 and gather following information:
---------------------------------------------------
- It is a structure (DW_TAG_structure_type)
- DW_AT_byte_size: It is 44 bytes wide
Search the structure Members in upcoming lines until 44 bytes are reached:
--------------------------------------------------------
1. Member (DW_TAG_member):
- DW_AT_name: Ref
- DW_AT_data_member_location: 200067fc + 0
- DW_AT_type: The data type can be found at line 38891:
- DW_TAG_typedef: float32_t
- DW_AT_type: The data type can be found at line 38883:
- DW_TAG_base_type: float
- DW_AT_byte_size: 4 bytes
2. Member (DW_TAG_member):
- DW_AT_name: Fdb
- DW_AT_data_member_location: 200067fc + 4
- DW_AT_type: The data type can be found at line 38891:
- DW_TAG_typedef: float32_t
- DW_AT_type: The data type can be found at line 38883:
- DW_TAG_base_type: float
- DW_AT_byte_size: 4 bytes
[left out Members 3-9]
10. Member (DW_TAG_member):
- DW_AT_name: OutMin
- DW_AT_data_member_location: 200067fc + 36
- DW_AT_type: The data type can be found at line 38891:
- DW_TAG_typedef: float32_t
- DW_AT_type: The data type can be found at line 38883:
- DW_TAG_base_type: float
- DW_AT_byte_size: 4 bytes
11. Member (DW_TAG_member):
- DW_AT_name: Out
- DW_AT_data_member_location: 200067fc + 40
- DW_AT_type: The data type can be found at line 38891:
- DW_TAG_typedef: float32_t
- DW_AT_type: The data type can be found at line 38883:
- DW_TAG_base_type: float
- DW_AT_byte_size: 4 bytes
坦白说，如上所述，一个脚本文件会自动收集信息，它比我的应用程序要复杂得多.另外，我必须承认我不太清楚如何编写这样的脚本.有没有更简单的方法来获取此类信息?尽管我认为我尝试了所有相关参数，但objdump是否有一些参数可以帮助我解决此问题?还是存在能够做到这一点的工具?最后，我需要一个这样的表(另外，最好在.elf文件中找到所有的枚举):
Frankly speaking, a script file, which automatically gathers the information as above mentioned, would be more complex than my application. Additionally I have to admit that I not really know how I could write such a script. Is there a more easy way to get this type of information? Is there maybe some parameter for the objdump which would help me with that, although I think I tried all the relevant ones? Or does a tool exist which is able to do this? In the end I need a table like this (additionally it would be nice to have all the enums which of course can also be found within the .elf file):
0x200067fc float BU_Uctrl_Udc_PI_Reg.Ref
0x20006800 float BU_Uctrl_Udc_PI_Reg.Fdb
[…]
0x20006832 float BU_Uctrl_Udc_PI_Reg.OutMin
0x20006836 float BU_Uctrl_Udc_PI_Reg.Out
The tool Fromelf http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0477c/index.html (included in Keil µVision) with the parameter --text exactly delivers such a table, but unfortunately I can’t use this because it supposedly needs the .elf or in this case called .axf files compiled with Arm Compiler Toolchain to work. Additionally there are license issues.
感谢任何提示.
推荐答案
您需要pahole吗?它可以转储具有大小和偏移量的可变结构.
is pahole what you need? it can dump variable structure with size and offset.
pahole −−reorganize −C foo xxx.out
struct foo {
int a; / 0 4 /
char c[4]; / 4 4 /
void b; / 8 8 /
long g; / 16 8 /
}; / size: 24, cachelines: 1 /
/ last cacheline: 24 bytes /
/ saved 8 bytes! /
这篇关于从使用ARM-GCC编译的elf文件中提取详细的符号信息(结构成员)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
