如何通过指令读取二进制可执行文件？
How to read binary executable by instructions?
有没有办法以编程方式从 x86 体系结构上的二进制可执行文件中读取给定数量的指令？
如果我有一个简单的 C 程序的二进制文件hello.c:
#include <stdio.h>
int main(){
printf("Hello world\n");
return 0;
}
使用 gcc 编译后，反汇编函数 main 如下所示：
000000000000063a <main>:
63a: 55 push %rbp
63b: 48 89 e5 mov %rsp,%rbp
63e: 48 8d 3d 9f 00 00 00 lea 0x9f(%rip),%rdi # 6e4 <_IO_stdin_used+0x4>
645: e8 c6 fe ff ff callq 510 <puts@plt>
64a: b8 00 00 00 00 mov [=11=]x0,%eax
64f: 5d pop %rbp
650: c3 retq
651: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
658: 00 00 00
65b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
在 C 中是否有一种简单的方法可以从 main 中读取例如前三个指令（意味着字节 55, 48, 89, e5, 48, 8d, 3d, 9f, 00, 00, 00）？不能保证函数看起来像这样——第一条指令可能有所有不同的操作码和大小。
这通过获取函数的地址并转换为 unsigned char 的指针来打印 main 函数的前 10 个字节，以十六进制打印。
这个小片段不算指令。为此，您需要一个指令大小 table（不是很困难，只是乏味，除非您发现 table 已经完成，What is the size of each asm instruction?）才能预测每条指令的大小第一个字节。
（当然，除非你的目标处理器有固定的指令大小，这使得问题很容易解决）
调试器也必须解码操作数，但在某些情况下，例如步进或跟踪，我怀疑他们有一个table方便计算下一个断点地址。
#include <stdio.h>
int main(){
printf("Hello world\n");
const unsigned char *start = (const char *)&main;
int i;
for (i=0;i<10;i++)
{
printf("%x\n",start[i]);
}
return 0;
}
输出：
Hello world
55
89
e5
83
e4
f0
83
ec
20
e8
似乎与反汇编匹配:)
00401630 <_main>:
401630: 55 push %ebp
401631: 89 e5 mov %esp,%ebp
401633: 83 e4 f0 and [=12=]xfffffff0,%esp
401636: 83 ec 20 sub [=12=]x20,%esp
401639: e8 a2 01 00 00 call 4017e0 <___main>
.globl _start
_start:
bl main
b .
.globl main
main:
add r1,#1
add r2,#1
add r3,#1
add r4,#1
b main
故意错误的体系结构，体系结构无关紧要文件格式重要。将其构建为非常流行的 elf 文件格式，这只是一种文件格式，我理解你的问题是读取文件，而不是修改二进制文件以从内存中读取程序 运行time .
它非常受欢迎，并且有一些工具可以做到这一点，您似乎知道如何 运行。
Disassembly of section .text:
00001000 <_start>:
1000: eb000000 bl 1008 <main>
1004: eafffffe b 1004 <_start+0x4>
00001008 <main>:
1008: e2811001 add r1, r1, #1
100c: e2822001 add r2, r2, #1
1010: e2833001 add r3, r3, #1
1014: e2844001 add r4, r4, #1
1018: eafffffa b 1008 <main>
如果我 hexdump 文件
00000000 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 02 00 28 00 01 00 00 00 00 10 00 00 34 00 00 00 |..(.........4...|
00000020 c0 11 00 00 00 02 00 05 34 00 20 00 01 00 28 00 |........4. ...(.|
00000030 06 00 05 00 01 00 00 00 00 00 00 00 00 00 00 00 |................|
00000040 00 00 00 00 1c 10 00 00 1c 10 00 00 05 00 00 00 |................|
00000050 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00001000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2 |............. ..|
00001010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11 00 00 |.0...@......A...|
00001020 00 61 65 61 62 69 00 01 07 00 00 00 08 01 00 00 |.aeabi..........|
00001030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00001040 00 00 00 00 00 10 00 00 00 00 00 00 03 00 01 00 |................|
00001050 00 00 00 00 00 00 00 00 00 00 00 00 03 00 02 00 |................|
00001060 01 00 00 00 00 00 00 00 00 00 00 00 04 00 f1 ff |................|
00001070 06 00 00 00 00 10 00 00 00 00 00 00 00 00 01 00 |................|
00001080 18 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
00001090 09 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010a0 17 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010b0 55 00 00 00 00 10 00 00 00 00 00 00 10 00 01 00 |U...............|
000010c0 23 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |#...............|
000010d0 2f 00 00 00 08 10 00 00 00 00 00 00 10 00 01 00 |/...............|
000010e0 34 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |4...............|
000010f0 3c 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |<...............|
00001100 43 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |C...............|
00001110 48 00 00 00 00 00 08 00 00 00 00 00 10 00 01 00 |H...............|
00001120 4f 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |O...............|
00001130 00 73 6f 2e 6f 00 24 61 00 5f 5f 62 73 73 5f 73 |.so.o.$a.__bss_s|
00001140 74 61 72 74 5f 5f 00 5f 5f 62 73 73 5f 65 6e 64 |tart__.__bss_end|
00001150 5f 5f 00 5f 5f 62 73 73 5f 73 74 61 72 74 00 6d |__.__bss_start.m|
00001160 61 69 6e 00 5f 5f 65 6e 64 5f 5f 00 5f 65 64 61 |ain.__end__._eda|
00001170 74 61 00 5f 65 6e 64 00 5f 73 74 61 63 6b 00 5f |ta._end._stack._|
00001180 5f 64 61 74 61 5f 73 74 61 72 74 00 00 2e 73 79 |_data_start...sy|
00001190 6d 74 61 62 00 2e 73 74 72 74 61 62 00 2e 73 68 |mtab..strtab..sh|
000011a0 73 74 72 74 61 62 00 2e 74 65 78 74 00 2e 41 52 |strtab..text..AR|
000011b0 4d 2e 61 74 74 72 69 62 75 74 65 73 00 00 00 00 |M.attributes....|
000011c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000011e0 00 00 00 00 00 00 00 00 1b 00 00 00 01 00 00 00 |................|
000011f0 06 00 00 00 00 10 00 00 00 10 00 00 1c 00 00 00 |................|
00001200 00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 |................|
00001210 21 00 00 00 03 00 00 70 00 00 00 00 00 00 00 00 |!......p........|
00001220 1c 10 00 00 12 00 00 00 00 00 00 00 00 00 00 00 |................|
00001230 01 00 00 00 00 00 00 00 01 00 00 00 02 00 00 00 |................|
00001240 00 00 00 00 00 00 00 00 30 10 00 00 00 01 00 00 |........0.......|
00001250 04 00 00 00 05 00 00 00 04 00 00 00 10 00 00 00 |................|
00001260 09 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 |................|
00001270 30 11 00 00 5c 00 00 00 00 00 00 00 00 00 00 00 |0...\...........|
00001280 01 00 00 00 00 00 00 00 11 00 00 00 03 00 00 00 |................|
00001290 00 00 00 00 00 00 00 00 8c 11 00 00 31 00 00 00 |............1...|
000012a0 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 |................|
000012b0
可以 google 文件格式并在维基百科上找到很多信息，在 links
之一中可以找到更多信息
有用的header信息
00 10 00 00 entrh
34 00 00 00 phoff
c0 11 00 00 shoff
00 02 00 05 flags
34 00 ehsize
20 00 phentsize
01 00 phnum
28 00 shentsize
06 00 shnum
05 00shstrndx
因此，如果我查看这些部分的开头，就会发现它们的编号为 shnum
0x11C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x11E8 1b 00 00 00 01 00 00 00 06 00 00 00 00 10 00 00 00 10 00 00
0x1210 21 00 00 00 03 00 00 70 00 00 00 00 00 00 00 00 1c 10 00 00
0x1238 01 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 30 10 00 00
0x1260 09 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 30 11 00 00
0x1288 11 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 8c 11 00 00
0x1260 strtab 类型偏移量 0x1130，它被分解为空终止字符串，直到您遇到双空
[0] 00
[1] 73 6f 2e 6f 00 so.o
[2] 24 61 00 $a
[3] 5f 5f 62 73 73 5f 73 74 61 72 74 5f 5f 00 __bss_start__
[4] 5f 5f 62 73 73 5f 65 6e 64 5f 5f 00 __bss_end__
[5] 5f 5f 62 73 73 5f 73 74 61 72 74 00 __bss_start
[6] 6d 61 69 6e 00 main
...
main 位于文件中的地址 0x115F，在文件中的偏移量为 0x2F
strtab.
0x1238 symtab 从 0x1030 开始，每个条目 0x10 或 16 字节
00001030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00001040 00 00 00 00 00 10 00 00 00 00 00 00 03 00 01 00 |................|
00001050 00 00 00 00 00 00 00 00 00 00 00 00 03 00 02 00 |................|
00001060 01 00 00 00 00 00 00 00 00 00 00 00 04 00 f1 ff |................|
00001070 06 00 00 00 00 10 00 00 00 00 00 00 00 00 01 00 |................|
00001080 18 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
00001090 09 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010a0 17 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010b0 55 00 00 00 00 10 00 00 00 00 00 00 10 00 01 00 |U...............|
000010c0 23 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |#...............|
000010d0 2f 00 00 00 08 10 00 00 00 00 00 00 10 00 01 00 |/...............|
000010e0 34 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |4...............|
000010f0 3c 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |<...............|
00001100 43 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |C...............|
00001110 48 00 00 00 00 00 08 00 00 00 00 00 10 00 01 00 |H...............|
00001120 4f 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |O...............|
000010d0 2f 00 00 00 在符号中有 0x2f 偏移 table
所以这是主要的，从这个条目中地址 08 10 00 00 或 0x1008
处理器内存，不幸的是，由于我选择的值恰好也是文件偏移量，请不要混淆。
此部分类型为 00000001 PROGBITS
0x11E8 1b 00 00 00 01 00 00 00 06 00 00 00 00 10 00 00 00 10 00 00
offset 0x1000 in the file 0x1C bytes
这是程序，机器代码。
00001000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2
00001010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11
所以从内存偏移量 0x1008 开始，它在
入口点（不幸的是我选择了一个错误的地址）我们需要
将 0x8 字节偏移量放入此数据
01 10 81 e2 01 20 82 e2
00001008 <main>:
1008: e2811001 add r1, r1, #1
100c: e2822001 add r2, r2, #1
1010: e2833001 add r3, r3, #1
这完全取决于文件，cpu 可能不太关心标签，main 只对人类有意义，而不是 cpu。
如果我把elf转换成其他格式完全可以执行table:
摩托罗拉的记录：
S00A0000736F2E7372656338
S1131000000000EBFEFFFFEA011081E2012082E212
S10F1010013083E2014084E2FAFFFFEAB1
S9031000EC
原始二进制图像
hexdump -C so.bin
00000000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2 |............. ..|
00000010 01 30 83 e2 01 40 84 e2 fa ff ff ea |.0...@......|
0000001c
感兴趣的指令字节当然在那里，但符号信息不存在。这取决于您对 1) 是否可以找到 "main" 感兴趣的文件格式，然后 2) 打印出该地址的前几个字节。
嗯，有点令人不安，但是如果你 link 为 0x2000 gnu ld 刻录一些磁盘 space 并将偏移量设置为 0x2000，但选择 0x20000000 并刻录更多磁盘 space 但没那么多
000100d0 2f 00 00 00 08 00 00 20 00 00 00 00 10 00 01 00
显示文件偏移量为 0x010010 但目标 space 中的地址为 0x20000008
00010010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11 00 00
00010020 00 61 65 61 62 69 00 01 07 00 00 00 08 01
只是 demonstrate/enforce 文件偏移量和目标内存 space 地址是两个不同的东西。
这是一种非常适合您想要执行的操作的格式
arm-none-eabi-objcopy -O symbolsrec so.elf so.srec
cat so.srec
$$ so.srec
$a 000000
_bss_end__ 01001c
__bss_start__ 01001c
__bss_end__ 01001c
_start 000000
__bss_start 01001c
main 000008
__end__ 01001c
_edata 01001c
_end 01001c
_stack 000
__data_start 01001c
$$
S0090000736F2E686578A1
S31520000000000000EBFEFFFFEA011081E2012082E200
S31120000010013083E2014084E2FAFFFFEA9F
S70520000000DA
有没有办法以编程方式从 x86 体系结构上的二进制可执行文件中读取给定数量的指令？
如果我有一个简单的 C 程序的二进制文件hello.c:
#include <stdio.h>
int main(){
printf("Hello world\n");
return 0;
}
使用 gcc 编译后，反汇编函数 main 如下所示：
000000000000063a <main>:
63a: 55 push %rbp
63b: 48 89 e5 mov %rsp,%rbp
63e: 48 8d 3d 9f 00 00 00 lea 0x9f(%rip),%rdi # 6e4 <_IO_stdin_used+0x4>
645: e8 c6 fe ff ff callq 510 <puts@plt>
64a: b8 00 00 00 00 mov [=11=]x0,%eax
64f: 5d pop %rbp
650: c3 retq
651: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
658: 00 00 00
65b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
在 C 中是否有一种简单的方法可以从 main 中读取例如前三个指令（意味着字节 55, 48, 89, e5, 48, 8d, 3d, 9f, 00, 00, 00）？不能保证函数看起来像这样——第一条指令可能有所有不同的操作码和大小。
这通过获取函数的地址并转换为 unsigned char 的指针来打印 main 函数的前 10 个字节，以十六进制打印。
这个小片段不算指令。为此，您需要一个指令大小 table（不是很困难，只是乏味，除非您发现 table 已经完成，What is the size of each asm instruction?）才能预测每条指令的大小第一个字节。
（当然，除非你的目标处理器有固定的指令大小，这使得问题很容易解决）
调试器也必须解码操作数，但在某些情况下，例如步进或跟踪，我怀疑他们有一个table方便计算下一个断点地址。
#include <stdio.h>
int main(){
printf("Hello world\n");
const unsigned char *start = (const char *)&main;
int i;
for (i=0;i<10;i++)
{
printf("%x\n",start[i]);
}
return 0;
}
输出：
Hello world
55
89
e5
83
e4
f0
83
ec
20
e8
似乎与反汇编匹配:)
00401630 <_main>:
401630: 55 push %ebp
401631: 89 e5 mov %esp,%ebp
401633: 83 e4 f0 and [=12=]xfffffff0,%esp
401636: 83 ec 20 sub [=12=]x20,%esp
401639: e8 a2 01 00 00 call 4017e0 <___main>
.globl _start
_start:
bl main
b .
.globl main
main:
add r1,#1
add r2,#1
add r3,#1
add r4,#1
b main
故意错误的体系结构，体系结构无关紧要文件格式重要。将其构建为非常流行的 elf 文件格式，这只是一种文件格式，我理解你的问题是读取文件，而不是修改二进制文件以从内存中读取程序 运行time .
它非常受欢迎，并且有一些工具可以做到这一点，您似乎知道如何 运行。
Disassembly of section .text:
00001000 <_start>:
1000: eb000000 bl 1008 <main>
1004: eafffffe b 1004 <_start+0x4>
00001008 <main>:
1008: e2811001 add r1, r1, #1
100c: e2822001 add r2, r2, #1
1010: e2833001 add r3, r3, #1
1014: e2844001 add r4, r4, #1
1018: eafffffa b 1008 <main>
如果我 hexdump 文件
00000000 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 02 00 28 00 01 00 00 00 00 10 00 00 34 00 00 00 |..(.........4...|
00000020 c0 11 00 00 00 02 00 05 34 00 20 00 01 00 28 00 |........4. ...(.|
00000030 06 00 05 00 01 00 00 00 00 00 00 00 00 00 00 00 |................|
00000040 00 00 00 00 1c 10 00 00 1c 10 00 00 05 00 00 00 |................|
00000050 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00001000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2 |............. ..|
00001010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11 00 00 |.0...@......A...|
00001020 00 61 65 61 62 69 00 01 07 00 00 00 08 01 00 00 |.aeabi..........|
00001030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00001040 00 00 00 00 00 10 00 00 00 00 00 00 03 00 01 00 |................|
00001050 00 00 00 00 00 00 00 00 00 00 00 00 03 00 02 00 |................|
00001060 01 00 00 00 00 00 00 00 00 00 00 00 04 00 f1 ff |................|
00001070 06 00 00 00 00 10 00 00 00 00 00 00 00 00 01 00 |................|
00001080 18 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
00001090 09 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010a0 17 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010b0 55 00 00 00 00 10 00 00 00 00 00 00 10 00 01 00 |U...............|
000010c0 23 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |#...............|
000010d0 2f 00 00 00 08 10 00 00 00 00 00 00 10 00 01 00 |/...............|
000010e0 34 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |4...............|
000010f0 3c 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |<...............|
00001100 43 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |C...............|
00001110 48 00 00 00 00 00 08 00 00 00 00 00 10 00 01 00 |H...............|
00001120 4f 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |O...............|
00001130 00 73 6f 2e 6f 00 24 61 00 5f 5f 62 73 73 5f 73 |.so.o.$a.__bss_s|
00001140 74 61 72 74 5f 5f 00 5f 5f 62 73 73 5f 65 6e 64 |tart__.__bss_end|
00001150 5f 5f 00 5f 5f 62 73 73 5f 73 74 61 72 74 00 6d |__.__bss_start.m|
00001160 61 69 6e 00 5f 5f 65 6e 64 5f 5f 00 5f 65 64 61 |ain.__end__._eda|
00001170 74 61 00 5f 65 6e 64 00 5f 73 74 61 63 6b 00 5f |ta._end._stack._|
00001180 5f 64 61 74 61 5f 73 74 61 72 74 00 00 2e 73 79 |_data_start...sy|
00001190 6d 74 61 62 00 2e 73 74 72 74 61 62 00 2e 73 68 |mtab..strtab..sh|
000011a0 73 74 72 74 61 62 00 2e 74 65 78 74 00 2e 41 52 |strtab..text..AR|
000011b0 4d 2e 61 74 74 72 69 62 75 74 65 73 00 00 00 00 |M.attributes....|
000011c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000011e0 00 00 00 00 00 00 00 00 1b 00 00 00 01 00 00 00 |................|
000011f0 06 00 00 00 00 10 00 00 00 10 00 00 1c 00 00 00 |................|
00001200 00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 |................|
00001210 21 00 00 00 03 00 00 70 00 00 00 00 00 00 00 00 |!......p........|
00001220 1c 10 00 00 12 00 00 00 00 00 00 00 00 00 00 00 |................|
00001230 01 00 00 00 00 00 00 00 01 00 00 00 02 00 00 00 |................|
00001240 00 00 00 00 00 00 00 00 30 10 00 00 00 01 00 00 |........0.......|
00001250 04 00 00 00 05 00 00 00 04 00 00 00 10 00 00 00 |................|
00001260 09 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 |................|
00001270 30 11 00 00 5c 00 00 00 00 00 00 00 00 00 00 00 |0...\...........|
00001280 01 00 00 00 00 00 00 00 11 00 00 00 03 00 00 00 |................|
00001290 00 00 00 00 00 00 00 00 8c 11 00 00 31 00 00 00 |............1...|
000012a0 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 |................|
000012b0
可以 google 文件格式并在维基百科上找到很多信息，在 links
之一中可以找到更多信息有用的header信息
00 10 00 00 entrh
34 00 00 00 phoff
c0 11 00 00 shoff
00 02 00 05 flags
34 00 ehsize
20 00 phentsize
01 00 phnum
28 00 shentsize
06 00 shnum
05 00shstrndx
因此，如果我查看这些部分的开头，就会发现它们的编号为 shnum
0x11C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x11E8 1b 00 00 00 01 00 00 00 06 00 00 00 00 10 00 00 00 10 00 00
0x1210 21 00 00 00 03 00 00 70 00 00 00 00 00 00 00 00 1c 10 00 00
0x1238 01 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 30 10 00 00
0x1260 09 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 30 11 00 00
0x1288 11 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 8c 11 00 00
0x1260 strtab 类型偏移量 0x1130，它被分解为空终止字符串，直到您遇到双空
[0] 00
[1] 73 6f 2e 6f 00 so.o
[2] 24 61 00 $a
[3] 5f 5f 62 73 73 5f 73 74 61 72 74 5f 5f 00 __bss_start__
[4] 5f 5f 62 73 73 5f 65 6e 64 5f 5f 00 __bss_end__
[5] 5f 5f 62 73 73 5f 73 74 61 72 74 00 __bss_start
[6] 6d 61 69 6e 00 main
...
main 位于文件中的地址 0x115F，在文件中的偏移量为 0x2F strtab.
0x1238 symtab 从 0x1030 开始，每个条目 0x10 或 16 字节
00001030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00001040 00 00 00 00 00 10 00 00 00 00 00 00 03 00 01 00 |................|
00001050 00 00 00 00 00 00 00 00 00 00 00 00 03 00 02 00 |................|
00001060 01 00 00 00 00 00 00 00 00 00 00 00 04 00 f1 ff |................|
00001070 06 00 00 00 00 10 00 00 00 00 00 00 00 00 01 00 |................|
00001080 18 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
00001090 09 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010a0 17 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |................|
000010b0 55 00 00 00 00 10 00 00 00 00 00 00 10 00 01 00 |U...............|
000010c0 23 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |#...............|
000010d0 2f 00 00 00 08 10 00 00 00 00 00 00 10 00 01 00 |/...............|
000010e0 34 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |4...............|
000010f0 3c 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |<...............|
00001100 43 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |C...............|
00001110 48 00 00 00 00 00 08 00 00 00 00 00 10 00 01 00 |H...............|
00001120 4f 00 00 00 1c 10 01 00 00 00 00 00 10 00 01 00 |O...............|
000010d0 2f 00 00 00 在符号中有 0x2f 偏移 table 所以这是主要的，从这个条目中地址 08 10 00 00 或 0x1008 处理器内存，不幸的是，由于我选择的值恰好也是文件偏移量，请不要混淆。
此部分类型为 00000001 PROGBITS
0x11E8 1b 00 00 00 01 00 00 00 06 00 00 00 00 10 00 00 00 10 00 00
offset 0x1000 in the file 0x1C bytes
这是程序，机器代码。
00001000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2
00001010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11
所以从内存偏移量 0x1008 开始，它在 入口点（不幸的是我选择了一个错误的地址）我们需要 将 0x8 字节偏移量放入此数据
01 10 81 e2 01 20 82 e2
00001008 <main>:
1008: e2811001 add r1, r1, #1
100c: e2822001 add r2, r2, #1
1010: e2833001 add r3, r3, #1
这完全取决于文件，cpu 可能不太关心标签，main 只对人类有意义，而不是 cpu。
如果我把elf转换成其他格式完全可以执行table:
摩托罗拉的记录：
S00A0000736F2E7372656338
S1131000000000EBFEFFFFEA011081E2012082E212
S10F1010013083E2014084E2FAFFFFEAB1
S9031000EC
原始二进制图像
hexdump -C so.bin
00000000 00 00 00 eb fe ff ff ea 01 10 81 e2 01 20 82 e2 |............. ..|
00000010 01 30 83 e2 01 40 84 e2 fa ff ff ea |.0...@......|
0000001c
感兴趣的指令字节当然在那里，但符号信息不存在。这取决于您对 1) 是否可以找到 "main" 感兴趣的文件格式，然后 2) 打印出该地址的前几个字节。
嗯，有点令人不安，但是如果你 link 为 0x2000 gnu ld 刻录一些磁盘 space 并将偏移量设置为 0x2000，但选择 0x20000000 并刻录更多磁盘 space 但没那么多
000100d0 2f 00 00 00 08 00 00 20 00 00 00 00 10 00 01 00
显示文件偏移量为 0x010010 但目标 space 中的地址为 0x20000008
00010010 01 30 83 e2 01 40 84 e2 fa ff ff ea 41 11 00 00
00010020 00 61 65 61 62 69 00 01 07 00 00 00 08 01
只是 demonstrate/enforce 文件偏移量和目标内存 space 地址是两个不同的东西。
这是一种非常适合您想要执行的操作的格式
arm-none-eabi-objcopy -O symbolsrec so.elf so.srec
cat so.srec
$$ so.srec
$a 000000
_bss_end__ 01001c
__bss_start__ 01001c
__bss_end__ 01001c
_start 000000
__bss_start 01001c
main 000008
__end__ 01001c
_edata 01001c
_end 01001c
_stack 000
__data_start 01001c
$$
S0090000736F2E686578A1
S31520000000000000EBFEFFFFEA011081E2012082E200
S31120000010013083E2014084E2FAFFFFEA9F
S70520000000DA