【Linux】GCC程序开发工具(下)

00. 目录

文章目录

00. 目录
01. GCC的二进制工具
02. objdump
03. objcopy命令
04. 总结
05. 附录

01. GCC的二进制工具

objdump 显示目标文件信息

objcopy 复制目标文件

02. objdump

objdump用于显示一个或者多个目标文件的信息，由其选项来控制显示那些特定的信息。可以通过objdump软件反汇编执行程序，获得执行程序的汇编格式。

objdump用法如下

deng@itcast:~$ objdump --help
用法：objdump <选项> <文件>显示来自目标 <文件> 的信息。至少必须给出以下选项之一：-a, --archive-headers    显示头信息-f, --file-headers       全面显示文件头-p, --private-headers    显示对象格式指定文件头信息-P, --private=OPT,OPT... Display object format specific contents-h, --[section-]headers  显示接头中的内容-x, --all-headers        显示所有可用到的头信息，包括符号表和重定位入口。-d, --disassemble        显示目标文件中的机器指令使用的汇编语言。该选项仅仅反汇编那些应该含有指令机器码的节。-D, --disassemble-all    反汇编所有节的内容--disassemble=<sym>  Display assembler contents from <sym>-S, --source             尽可能显示与反汇编混合的源代码--source-comment[=<txt>] Prefix lines of source code with <txt>-s, --full-contents      显示任何指定节的全部内容-g, --debugging          显示目标文件调试信息-e, --debugging-tags     显示目标文件使用ctags格式调试信息-G, --stabs              显示所有文件中的STABS信息-W[lLiaprmfFsoRtUuTgAckK] or--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges,=pubtypes,=gdb_index,=trace_info,=trace_abbrev,=trace_aranges,=addr,=cu_index,=links,=follow-links]Display DWARF info in the file--ctf=SECTION            Display CTF info from SECTION-t, --syms               显示符号表内容-T, --dynamic-syms       显示动态符号表内容-r, --reloc              显示文件的重定向入口-R, --dynamic-reloc      Display the dynamic relocation entries in the file@<file>                  Read options from <file>-v, --version            Display this program's version number-i, --info               List object formats and architectures supported-H, --help               Display this information以下选项是可选的：-b, --target=BFDNAME           指定目标对象格式为BFDNAME-m, --architecture=MACHINE     指定体系结构为MACHINE-j, --section=NAME             只显示名称为NAME的节信息-M, --disassembler-options=OPT 反汇编器中通过文本OPT-EB --endian=big               指定大端格式-EL --endian=little            指定小端格式--file-start-context       包含从文件开始的上下文(与-S一起使用)-I, --include=DIR              增加目录为搜索路径-l, --line-numbers             在输出中包含行号和文件名-F, --file-offsets             Include file offsets when displaying information-C, --demangle[=STYLE]         将底层的符号解码位用户层的符号The STYLE, if specified, can be `auto', `gnu',`lucid', `arm', `hp', `edg', `gnu-v3', `java'or `gnat'--recurse-limit            Enable a limit on recursion whilst demangling.  [Default]--no-recurse-limit         Disable a limit on recursion whilst demangling-w, --wide                     对超过80列的输出设备指定一些行的格式-z, --disassemble-zeroes       Do not skip blocks of zeroes when disassembling--start-address=ADDR       Only process data whose address is >= ADDR--stop-address=ADDR        Only process data whose address is < ADDR--prefix-addresses         Print complete address alongside disassembly--[no-]show-raw-insn       在符号反汇编前显示十六进制信息--insn-width=WIDTH         Display WIDTH bytes on a single line for -d--adjust-vma=OFFSET        在所有节地址前增加OFFSET偏移量--special-syms             在符号dumps中包含特殊符号--inlines                  Print all inlines for source line (with -l)--prefix=PREFIX            Add PREFIX to absolute paths for -S--prefix-strip=LEVEL       Strip initial directory names for -S--dwarf-depth=N        Do not display DIEs at depth N or greater--dwarf-start=N        Display DIEs starting with N, at the same depthor deeper--dwarf-check          Make additional dwarf internal consistency checks.      --ctf-parent=SECTION       Use SECTION as the CTF parent--visualize-jumps          Visualize jumps by drawing ASCII art lines--visualize-jumps=color    Use colors in the ASCII art--visualize-jumps=extended-color   Use extended 8-bit color codes--visualize-jumps=off      Disable jump visualizationobjdump：支持的目标： elf64-x86-64 elf32-i386 elf32-iamcu elf32-x86-64 pei-i386 pei-x86-64 elf64-l1om
elf64-k1om elf64-little elf64-big elf32-little elf32-big pe-x86-64 pe-bigobj-x86-64 pe-i386 srec
symbolsrec verilog tekhex binary ihex plugin
objdump：支持的体系结构： i386 i386:x86-64 i386:x64-32 i8086 i386:intel i386:x86-64:intel i386:x64-32:intel
i386:nacl i386:x86-64:nacl i386:x64-32:nacl iamcu iamcu:intel l1om l1om:intel k1om k1om:intelThe following i386/x86-64 specific disassembler options are supported for use
with the -M switch (multiple options should be separated by commas):x86-64      Disassemble in 64bit modei386        Disassemble in 32bit modei8086       Disassemble in 16bit modeatt         Display instruction in AT&T syntaxintel       Display instruction in Intel syntaxatt-mnemonicDisplay instruction in AT&T mnemonicintel-mnemonicDisplay instruction in Intel mnemonicaddr64      Assume 64bit address sizeaddr32      Assume 32bit address sizeaddr16      Assume 16bit address sizedata32      Assume 32bit data sizedata16      Assume 16bit data sizesuffix      Always display instruction suffix in AT&T syntaxamd64       Display instruction in AMD64 ISAintel64     Display instruction in Intel64 ISA
将 bug 报告到 <http://www.sourceware.org/bugzilla/>。
deng@itcast:~$

2.1 查看目标文件ELF头信息

deng@itcast:~/share/3rd/1static_lib$ objdump -h add.oadd.o：     文件格式 elf64-x86-64节：
Idx Name          Size      VMA               LMA               File off  Algn0 .text         00000018  0000000000000000  0000000000000000  00000040  2**0CONTENTS, ALLOC, LOAD, READONLY, CODE1 .data         00000000  0000000000000000  0000000000000000  00000058  2**0CONTENTS, ALLOC, LOAD, DATA2 .bss          00000000  0000000000000000  0000000000000000  00000058  2**0ALLOC3 .comment      00000025  0000000000000000  0000000000000000  00000058  2**0CONTENTS, READONLY4 .note.GNU-stack 00000000  0000000000000000  0000000000000000  0000007d  2**0CONTENTS, READONLY5 .note.gnu.property 00000020  0000000000000000  0000000000000000  00000080  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA6 .eh_frame     00000038  0000000000000000  0000000000000000  000000a0  2**3CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
deng@itcast:~/share/3rd/1static_lib$

2.2 查看可执行文件ELF头信息

deng@itcast:~/test$ objdump -h a.out a.out：     文件格式 elf64-x86-64节：
Idx Name          Size      VMA               LMA               File off  Algn0 .interp       0000001c  0000000000000318  0000000000000318  00000318  2**0CONTENTS, ALLOC, LOAD, READONLY, DATA1 .note.gnu.property 00000020  0000000000000338  0000000000000338  00000338  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA2 .note.gnu.build-id 00000024  0000000000000358  0000000000000358  00000358  2**2CONTENTS, ALLOC, LOAD, READONLY, DATA3 .note.ABI-tag 00000020  000000000000037c  000000000000037c  0000037c  2**2CONTENTS, ALLOC, LOAD, READONLY, DATA4 .gnu.hash     00000024  00000000000003a0  00000000000003a0  000003a0  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA5 .dynsym       000000a8  00000000000003c8  00000000000003c8  000003c8  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA6 .dynstr       00000082  0000000000000470  0000000000000470  00000470  2**0CONTENTS, ALLOC, LOAD, READONLY, DATA7 .gnu.version  0000000e  00000000000004f2  00000000000004f2  000004f2  2**1CONTENTS, ALLOC, LOAD, READONLY, DATA8 .gnu.version_r 00000020  0000000000000500  0000000000000500  00000500  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA9 .rela.dyn     000000c0  0000000000000520  0000000000000520  00000520  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA10 .rela.plt     00000018  00000000000005e0  00000000000005e0  000005e0  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA11 .init         0000001b  0000000000001000  0000000000001000  00001000  2**2CONTENTS, ALLOC, LOAD, READONLY, CODE12 .plt          00000020  0000000000001020  0000000000001020  00001020  2**4CONTENTS, ALLOC, LOAD, READONLY, CODE13 .plt.got      00000010  0000000000001040  0000000000001040  00001040  2**4CONTENTS, ALLOC, LOAD, READONLY, CODE14 .plt.sec      00000010  0000000000001050  0000000000001050  00001050  2**4CONTENTS, ALLOC, LOAD, READONLY, CODE15 .text         00000185  0000000000001060  0000000000001060  00001060  2**4CONTENTS, ALLOC, LOAD, READONLY, CODE16 .fini         0000000d  00000000000011e8  00000000000011e8  000011e8  2**2CONTENTS, ALLOC, LOAD, READONLY, CODE17 .rodata       00000010  0000000000002000  0000000000002000  00002000  2**2CONTENTS, ALLOC, LOAD, READONLY, DATA18 .eh_frame_hdr 00000044  0000000000002010  0000000000002010  00002010  2**2CONTENTS, ALLOC, LOAD, READONLY, DATA19 .eh_frame     00000108  0000000000002058  0000000000002058  00002058  2**3CONTENTS, ALLOC, LOAD, READONLY, DATA20 .init_array   00000008  0000000000003db8  0000000000003db8  00002db8  2**3CONTENTS, ALLOC, LOAD, DATA21 .fini_array   00000008  0000000000003dc0  0000000000003dc0  00002dc0  2**3CONTENTS, ALLOC, LOAD, DATA22 .dynamic      000001f0  0000000000003dc8  0000000000003dc8  00002dc8  2**3CONTENTS, ALLOC, LOAD, DATA23 .got          00000048  0000000000003fb8  0000000000003fb8  00002fb8  2**3CONTENTS, ALLOC, LOAD, DATA24 .data         00000010  0000000000004000  0000000000004000  00003000  2**3CONTENTS, ALLOC, LOAD, DATA25 .bss          00000008  0000000000004010  0000000000004010  00003010  2**0ALLOC26 .comment      00000024  0000000000000000  0000000000000000  00003010  2**0CONTENTS, READONLY
deng@itcast:~/test$

2.3 对二进制文件进行反汇编

deng@itcast:~/share/3rd/1static_lib$ objdump -D add.o add.o：     文件格式 elf64-x86-64Disassembly of section .text:0000000000000000 <add>:0:   f3 0f 1e fa             endbr64 4:   55                      push   %rbp5:   48 89 e5                mov    %rsp,%rbp8:   89 7d fc                mov    %edi,-0x4(%rbp)b:   89 75 f8                mov    %esi,-0x8(%rbp)e:   8b 55 fc                mov    -0x4(%rbp),%edx11:   8b 45 f8                mov    -0x8(%rbp),%eax14:   01 d0                   add    %edx,%eax16:   5d                      pop    %rbp17:   c3                      retq   Disassembly of section .comment:0000000000000000 <.comment>:0:   00 47 43                add    %al,0x43(%rdi)3:   43 3a 20                rex.XB cmp (%r8),%spl6:   28 55 62                sub    %dl,0x62(%rbp)9:   75 6e                   jne    79 <add+0x79>b:   74 75                   je     82 <add+0x82>d:   20 39                   and    %bh,(%rcx)f:   2e 33 2e                xor    %cs:(%rsi),%ebp12:   30 2d 31 30 75 62       xor    %ch,0x62753031(%rip)        # 62753049 <add+0x62753049>18:   75 6e                   jne    88 <add+0x88>1a:   74 75                   je     91 <add+0x91>1c:   32 29                   xor    (%rcx),%ch1e:   20 39                   and    %bh,(%rcx)20:   2e 33 2e                xor    %cs:(%rsi),%ebp23:   30 00                   xor    %al,(%rax)Disassembly of section .note.gnu.property:0000000000000000 <.note.gnu.property>:0:   04 00                   add    $0x0,%al2:   00 00                   add    %al,(%rax)4:   10 00                   adc    %al,(%rax)6:   00 00                   add    %al,(%rax)8:   05 00 00 00 47          add    $0x47000000,%eaxd:   4e 55                   rex.WRX push %rbpf:   00 02                   add    %al,(%rdx)11:   00 00                   add    %al,(%rax)13:   c0 04 00 00             rolb   $0x0,(%rax,%rax,1)17:   00 03                   add    %al,(%rbx)19:   00 00                   add    %al,(%rax)1b:   00 00                   add    %al,(%rax)1d:   00 00                   add    %al,(%rax)...Disassembly of section .eh_frame:0000000000000000 <.eh_frame>:0:   14 00                   adc    $0x0,%al2:   00 00                   add    %al,(%rax)4:   00 00                   add    %al,(%rax)6:   00 00                   add    %al,(%rax)8:   01 7a 52                add    %edi,0x52(%rdx)b:   00 01                   add    %al,(%rcx)d:   78 10                   js     1f <.eh_frame+0x1f>f:   01 1b                   add    %ebx,(%rbx)11:   0c 07                   or     $0x7,%al13:   08 90 01 00 00 1c       or     %dl,0x1c000001(%rax)19:   00 00                   add    %al,(%rax)1b:   00 1c 00                add    %bl,(%rax,%rax,1)1e:   00 00                   add    %al,(%rax)20:   00 00                   add    %al,(%rax)22:   00 00                   add    %al,(%rax)24:   18 00                   sbb    %al,(%rax)26:   00 00                   add    %al,(%rax)28:   00 45 0e                add    %al,0xe(%rbp)2b:   10 86 02 43 0d 06       adc    %al,0x60d4302(%rsi)31:   4f 0c 07                rex.WRXB or $0x7,%al34:   08 00                   or     %al,(%rax)...
deng@itcast:~/share/3rd/1static_lib$

03. objcopy命令

objcopy工具用于对某种格式的目标文件内容进行转换，输出为另一种格式的目标文件。objcopy使用GNU BFD库读写目标文件，通过这个BFD库，objcopy能够以一种不同与源目标文件的格式来生成目标文件。

objcopy通过访问BFD库中描述的所有格式的目标文件来识别大部分可执行文件的格式。例如，指定"srec"的输出目标格式(使用 -O srec),objcopy就能够生成S-records格式的目标文件。如果指定"binary"的输出目标格式(使用-O binary)。objcopy能够生成原始的二进制文件，即通常所说的image文件。当objcopy生成一个原始的二进制文件时，它必然会产生输入目标文件内容的一个内存信息存储。所有的符号和重定位信息将被丢弃，且内存信息转储将从已经复制到输出文件的最底端的虚拟地址开始。当生成S-record或原始二进制文件时，使用-S有助于objcopy工具取出元文件中包含的调试信息。在某系情况下，-R可以用于去除二进制文件并不需要的信息。

deng@itcast:~/share/3rd/1static_lib$ objcopy --help
用法：objcopy [选项] 输入文件 [输出文件]复制二进制文件，可能在此过程中进行变换选项为：-I --input-target <bfdname>      假设输入文件格式为bfdname-O --output-target <bfdname>     建立格式为bfdname的输出文件-B --binary-architecture <arch>  当输入为二进制文件的时候，指定输出的架构-F --target <bfdname>            设定输入和输出文件格式为bdfname--debugging                   如果有可能，转换调试信息-p --preserve-dates              保留修改 访问输出的时间戳-D --enable-deterministic-archivesProduce deterministic output when stripping archives (default)-U --disable-deterministic-archivesDisable -D behavior-j --only-section <name>         只复制名称为name的节到输出--add-gnu-debuglink=<file>    增加.gnu_debuglink节连接到<file>-R --remove-section <name>       从输出中删除名为name的节--remove-relocations <name>   Remove relocations from section <name>-S --strip-all                   不复制源文件中重定位和符号信息-g --strip-debug                 不复制元文件中的调试信息--strip-dwo                   Remove all DWO sections--strip-unneeded              Remove all symbols not needed by relocations-N --strip-symbol <name>         不复制符号<name>--strip-unneeded-symbol <name>取出重定位处理不需要的所有符号--only-keep-debug             只保留调试符号--extract-dwo                 Copy only DWO sections--extract-symbol              Remove section contents but keep symbols--keep-section <name>         Do not strip section <name>-K --keep-symbol <name>          Do not strip symbol <name>--keep-file-symbols           Do not strip file symbol(s)--localize-hidden             Turn all ELF hidden symbols into locals-L --localize-symbol <name>      强制符号name定义为局部的--globalize-symbol <name>     Force symbol <name> to be marked as a global-G --keep-global-symbol <name>   除了名称为name的符号，其它符号局部化-W --weaken-symbol <name>        Force symbol <name> to be marked as a weak--weaken                      弱化文件中所有全局符号-w --wildcard                    允许在符号比较中使用通配符-x --discard-all                 不从源文件中复制非全局符号-X --discard-locals              不复制编译器生成的局部符号-i --interleave[=<number>]       只从number个字节中复制一份--interleave-width <number>   Set N for --interleave-b --byte <num>                  Select byte <num> in every interleaved block--gap-fill <val>              Fill gaps between sections with <val>--pad-to <addr>               Pad the last section up to address <addr>--set-start <addr>            Set the start address to <addr>{--change-start|--adjust-start} <incr>Add <incr> to the start address{--change-addresses|--adjust-vma} <incr>Add <incr> to LMA, VMA and start addresses{--change-section-address|--adjust-section-vma} <name>{=|+|-}<val>Change LMA and VMA of section <name> by <val>--change-section-lma <name>{=|+|-}<val>Change the LMA of section <name> by <val>--change-section-vma <name>{=|+|-}<val>Change the VMA of section <name> by <val>{--[no-]change-warnings|--[no-]adjust-warnings}Warn if a named section does not exist--set-section-flags <name>=<flags>Set section <name>'s properties to <flags>--set-section-alignment <name>=<align>Set section <name>'s alignment to <align> bytes--add-section <name>=<file>   Add section <name> found in <file> to output--update-section <name>=<file>Update contents of section <name> withcontents found in <file>--dump-section <name>=<file>  Dump the contents of section <name> into <file>--rename-section <old>=<new>[,<flags>] Rename section <old> to <new>--long-section-names {enable|disable|keep}Handle long section names in Coff objects.--change-leading-char         Force output format's leading character style--remove-leading-char         Remove leading character from global symbols--reverse-bytes=<num>         Reverse <num> bytes at a time, in output sections with content--redefine-sym <old>=<new>    Redefine symbol name <old> to <new>--redefine-syms <file>        --redefine-sym for all symbol pairs listed in <file>--srec-len <number>           Restrict the length of generated Srecords--srec-forceS3                Restrict the type of generated Srecords to S3--strip-symbols <file>        -N for all symbols listed in <file>--strip-unneeded-symbols <file>--strip-unneeded-symbol for all symbols listedin <file>--keep-symbols <file>         -K for all symbols listed in <file>--localize-symbols <file>     -L for all symbols listed in <file>--globalize-symbols <file>    --globalize-symbol for all in <file>--keep-global-symbols <file>  -G for all symbols listed in <file>--weaken-symbols <file>       -W for all symbols listed in <file>--add-symbol <name>=[<section>:]<value>[,<flags>]  Add a symbol--alt-machine-code <index>    Use the target's <index>'th alternative machine--writable-text               Mark the output text as writable--readonly-text               Make the output text write protected--pure                        Mark the output file as demand paged--impure                      Mark the output file as impure--prefix-symbols <prefix>     Add <prefix> to start of every symbol name--prefix-sections <prefix>    Add <prefix> to start of every section name--prefix-alloc-sections <prefix>Add <prefix> to start of every allocatablesection name--file-alignment <num>        Set PE file alignment to <num>--heap <reserve>[,<commit>]   Set PE reserve/commit heap to <reserve>/<commit>--image-base <address>        Set PE image base to <address>--section-alignment <num>     Set PE section alignment to <num>--stack <reserve>[,<commit>]  Set PE reserve/commit stack to <reserve>/<commit>--subsystem <name>[:<version>]Set PE subsystem to <name> [& <version>]--compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi}]Compress DWARF debug sections using zlib--decompress-debug-sections   Decompress DWARF debug sections using zlib--elf-stt-common=[yes|no]     Generate ELF common symbols with STT_COMMONtype--verilog-data-width <number> Specifies data width, in bytes, for verilog output-M  --merge-notes                Remove redundant entries in note sections--no-merge-notes             Do not attempt to remove redundant notes (default)-v --verbose                     List all object files modified@<file>                          Read options from <file>-V --version                     Display this program's version number-h --help                        Display this output--info                        List object formats & architectures supported
objcopy：支持的目标： elf64-x86-64 elf32-i386 elf32-iamcu elf32-x86-64 pei-i386 pei-x86-64 elf64-l1om elf64-k1om
elf64-little elf64-big elf32-little elf32-big pe-x86-64 pe-bigobj-x86-64 pe-i386 srec symbolsrec verilog tekhex
binary ihex plugin
将 bug 报告到 <http://www.sourceware.org/bugzilla/>
deng@itcast:~/share/3rd/1static_lib$

3.1 生成纯二进制文件

deng@itcast:~/test$ gcc test.c -o test
deng@itcast:~/test$ objcopy test -O binary test_bindata# 仅包含机器码和数据
deng@itcast:~/test$ file test_bindata
test_bindata: data
deng@itcast:~/test$

3.2 生成S-record格式的文件

deng@itcast:~/test$ objcopy test -O srec test_srec
deng@itcast:~/test$ file test_srec
test_srec: Motorola S-Record; binary data in text format
deng@itcast:~/test$

3.3 更改部分输出文件的信息

# -S选项表示不复制重定位和符号信息 生成去掉符号后的可执行文件 与strip类似
deng@itcast:~/test$ objcopy test -S test_stripped
deng@itcast:~/test$ nm test_stripped
nm: test_stripped：无符号
deng@itcast:~/test$

3.4 指定要删除的段

# 删除了数据段的可执行文件
deng@itcast:~/test$ objcopy test -R .data test_removed
deng@itcast:~/test$ ./test_removed
hello world
deng@itcast:~/test$

3.5 应用示例

#include <stdio.h>int bss_arrary[1024 * 1024] = {0};int main(void)
{printf("hello world\n");return 0;
}

编译之后的代码

deng@itcast:~/test$ gcc test.c -o test
deng@itcast:~/test$ size testtext    data     bss     dec     hex filename1565     600 4194336 4196501  400895 test
deng@itcast:~/test$
deng@itcast:~/test$ ls -lh test
-rwxrwxr-x 1 deng deng 17K 6月  18 22:31 test
deng@itcast:~/test$ # 使用strip去掉符号
deng@itcast:~/test$ strip test -o test_strip
deng@itcast:~/test$ ls -lh test test_strip
-rwxrwxr-x 1 deng deng 17K 6月  18 22:31 test
-rwxrwxr-x 1 deng deng 15K 6月  18 22:32 test_strip
deng@itcast:~/test$ deng@itcast:~/test$ objcopy -R .comment -R .note.ABI-tag -R .gnu.version test test1
deng@itcast:~/test$ ls -lh test test1
-rwxrwxr-x 1 deng deng 17K 6月  18 22:31 test
-rwxrwxr-x 1 deng deng 16K 6月  18 22:34 test1
deng@itcast:~/test$

04. 总结

GCC二进制工具中，ar用于生成归档文件，readelf、string、nm、objdump属于信息获取工具，strip、objcopy属于目标文件转换工具。

05. 附录

5.1 【Linux】GCC程序开发工具(上)
5.2 【Linux】GCC程序开发工具(中)
5.3 【Linux】GCC程序开发工具(下)