我有来自二进制炸弹实验室的以下汇编程序。目的是确定在不触发explode_bomb函数的情况下运行二进制文件所需的关键字。我评论了我对该程序的程序集的分析，但无法将所有内容拼凑在一起。我还想强调一点，我不是要寻找实际的答案，而是要了解程序集的工作原理，并查看到目前为止我的分析是否正确。
我检查了内存位置0x80490ab，发现它只包含一个字母字符串，而不是我要查找的关键字。我对这行特别困惑：rep movsl %ds:(%esi),%es:(%edi)和这两个寄存器之间实际复制的内容。我也不确定在进行实际比较之前，这之后的以下几行实际上是做什么的（列在问题的底部）。我将不胜感激！
以下是反汇编程序本身：
0x08048c3c <+0>: push %edi
0x08048c3d <+1>: push %esi
0x08048c3e <+2>: sub $0x14,%esp
0x08048c41 <+5>: movl $0x804a388,(%esp)
0x08048c48 <+12>: call 0x80490ab <string_length>
0x08048c4d <+17>: add $0x1,%eax
0x08048c50 <+20>: mov %eax,(%esp)
0x08048c53 <+23>: call 0x8048800 <malloc@plt>
0x08048c58 <+28>: mov $0x804a388,%esi
0x08048c5d <+33>: mov $0x13,%ecx
0x08048c62 <+38>: mov %eax,%edi
0x08048c64 <+40>: rep movsl %ds:(%esi),%es:(%edi)
0x08048c66 <+42>: movzwl (%esi),%edx
0x08048c69 <+45>: mov %dx,(%edi)
0x08048c6c <+48>: movzbl 0x11(%eax),%edx
0x08048c70 <+52>: mov %dl,0x10(%eax)
0x08048c73 <+55>: mov %eax,0x4(%esp)
0x08048c77 <+59>: mov 0x20(%esp),%eax
0x08048c7b <+63>: mov %eax,(%esp)
0x08048c7e <+66>: call 0x80490ca <strings_not_equal>
0x08048c83 <+71>: test %eax,%eax
0x08048c85 <+73>: je 0x8048c8c <phase_3+80>
0x08048c87 <+75>: call 0x8049363 <explode_bomb>
0x08048c8c <+80>: add $0x14,%esp
0x08048c8f <+83>: pop %esi
0x08048c90 <+84>: pop %edi
0x08048c91 <+85>: ret
以下块包含我的分析
5 <phase_3>
6 0x08048c3c <+0>: push %edi // push value in edi to stack
7 0x08048c3d <+1>: push %esi // push value of esi to stack
8 0x08048c3e <+2>: sub $0x14,%esp // grow stack by 0x14 (move stack ptr -0x14 bytes)
9
10 0x08048c41 <+5>: movl $0x804a388,(%esp) // put 0x804a388 into loc esp points to
11
12 0x08048c48 <+12>: call 0x80490ab <string_length> // check string length, store in eax
13 0x08048c4d <+17>: add $0x1,%eax // increment val in eax by 0x1 (str len + 1)
14 // at this point, eax = str_len + 1 = 77 + 1 = 78
15
16 0x08048c50 <+20>: mov %eax,(%esp) // get val in eax and put in loc on stack
17 //**** at this point, 0x804a388 should have a value of 78? ****
18
19 0x08048c53 <+23>: call 0x8048800 <malloc@plt> // malloc --> base ptr in eax
20
21 0x08048c58 <+28>: mov $0x804a388,%esi // 0x804a388 in esi
22 0x08048c5d <+33>: mov $0x13,%ecx // put 0x13 in ecx (counter register)
23 0x08048c62 <+38>: mov %eax,%edi // put val in eax into edi
24 0x08048c64 <+40>: rep movsl %ds:(%esi),%es:(%edi) // repeat 0x13 (19) times
25 // **** populate malloced memory with first 19 (edit: 76) chars of string at 0x804a388? ****
26
27 0x08048c66 <+42>: movzwl (%esi),%edx // put val in loc esi points to into edx
28
29 0x08048c69 <+45>: mov %dx,(%edi) // put val in dx to loc edi points to
30 0x08048c6c <+48>: movzbl 0x11(%eax),%edx // edx = [eax + 0x11]
31 0x08048c70 <+52>: mov %dl,0x10(%eax) // [eax + 0x10] = dl
32 0x08048c73 <+55>: mov %eax,0x4(%esp) // [esp + 0x4] = eax
33 0x08048c77 <+59>: mov 0x20(%esp),%eax // eax = [esp + 0x20]
34 0x08048c7b <+63>: mov %eax,(%esp) // put val in eax into loc esp points to
35
36 // edi --> first arg
37 // esi --> second arg
38 // compare value in esi to edi
39 0x08048c7e <+66>: call 0x80490ca <strings_not_equal> // store result in eax
40 0x08048c83 <+71>: test %eax,%eax
41 0x08048c85 <+73>: je 0x8048c8c <phase_3+80>
42 0x08048c87 <+75>: call 0x8049363 <explode_bomb>
43 0x08048c8c <+80>: add $0x14,%esp
44 0x08048c8f <+83>: pop %esi
45 0x08048c90 <+84>: pop %edi
46 0x08048c91 <+85>: ret
除了所有这些，我的一些主要问题是：
rep movsl将32位长字从地址%esi复制到地址%edi，每次都递增4，等于%ecx的次数。将其视为memcpy(edi, esi, ecx*4)。
请参阅https://felixcloutier.com/x86/movs:movsb:movsw:movsd:movsq（在Intel表示法中为movsd）。
因此，这正在复制19*4=76字节。