debugging – 从使用ARM-GCC编译的elf文件中提取详细的符号信息(struct members)

我正在使用ARM-GCC 4.7.4来编译Cortex-M4的代码.对于我们的调试工具,我需要了解人类可读格式的所有变量的名称,类型和地址(例如.txt).地图文件提供了大部分信息,遗憾的是不适用于以下结构内容:

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,我尝试使用工具nm,readelf和objdump从.elf文件中获取一些内容,该文件是使用dwarf-2格式的参数-g3编译的.只有使用objdump我才能找到我搜索过的信息:

objdump –Wi myfile.elf >symbols.txt

有关typedef PI_REG的以下信息可以在symbols.txt文件中找到:

 <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)

[省略结构成员有抵消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)

如果我想获得有关变量的信息,例如结构BU_Uctrl_Udc_PI_Reg,我必须做以下事情:

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

坦率地说,如上所述自动收集信息的脚本文件比我的应用程序更复杂.另外我不得不承认我真的不知道怎么写这样的剧本.是否有更简单的方法来获取此类信息? objdump可能有一些参数可以帮助我,虽然我认为我尝试了所有相关的参数?或者是否存在能够执行此操作的工具?最后我需要一个像这样的表(另外,所有的枚举当然也可以在.elf文件中找到)会很好:

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

带有参数–text的工具Fromelf http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0477c/index.html(包括在KeilμVision中)正好提供了这样一个表,但不幸的是我不能使用它,因为它应该需要.elf或者在这种情况下称为.axf文件,用Arm Compiler Toolchain编译上班.此外还有许可证问题.

谢谢你的任何提示.

最佳答案 您可以使用eclipse CDT的gdb mi接口以编程方式获取此信息.

private def loadElfFile(String elfFilePath) {
    var plugin = new MIPlugin

    var file = new File(elfFilePath)

    var cmdFactory = new CommandFactory("mi2")
    session = plugin.createSession(
        MISession::PROGRAM,
        'gdb',
        cmdFactory,
        file,
        #[],
        true,
        new NullProgressMonitor
    )
}

在那里,您可以查询全局变量及其类型.地址存储在值的hexAddress属性中.

这种方法的问题在于它的缓慢性.具有50个成员的结构需要大约10秒的时间来处理.查询所有结构将需要几分钟.对于IDE工具用例(如模型转换),这是不切实际的.你必须深入了解精灵和矮人.

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