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  • C到汇编[1]

    这篇文字解释这个问题:C语言函数调用在汇编语言是怎么实现的?栈模型很好的满足了函数调用的需求,以最简单的函数调用说明。

     1 5:    int add2(int a, int b){return a+b;}
     2 0040B450   push        ebp
     3 0040B451   mov         ebp,esp
     4 0040B453   sub         esp,40h
     5 0040B456   push        ebx
     6 0040B457   push        esi
     7 0040B458   push        edi
     8 0040B459   lea         edi,[ebp-40h]
     9 0040B45C   mov         ecx,10h
    10 0040B461   mov         eax,0CCCCCCCCh
    11 0040B466   rep stos    dword ptr [edi]
    12 0040B468   mov         eax,dword ptr [ebp+8]
    13 0040B46B   add         eax,dword ptr [ebp+0Ch]
    14 0040B46E   pop         edi
    15 0040B46F   pop         esi
    16 0040B470   pop         ebx
    17 0040B471   mov         esp,ebp
    18 0040B473   pop         ebp
    19 0040B474   ret
    20 
    21 --- No source file  ---------------------------------------------------------------------------------------------------------------------------------------
    22 0040B76C   int         3
    23 0040B76D   int         3
    24 0040B76E   int         3
    25 0040B76F   int         3
    26 --- e:项目00test	estconsolemain.cpp  -----------------------------------------------------------------------------------------------------------------
    27 6:
    28 7:    int main(int argc, char **argv){
    29 0040B770   push        ebp
    30 0040B771   mov         ebp,esp
    31 0040B773   sub         esp,4Ch
    32 0040B776   push        ebx
    33 0040B777   push        esi
    34 0040B778   push        edi
    35 0040B779   lea         edi,[ebp-4Ch]
    36 0040B77C   mov         ecx,13h
    37 0040B781   mov         eax,0CCCCCCCCh
    38 0040B786   rep stos    dword ptr [edi]
    39 8:
    40 9:        int a = 10;
    41 0040B788   mov         dword ptr [ebp-4],0Ah
    42 10:       int b = 20;
    43 0040B78F   mov         dword ptr [ebp-8],14h
    44 11:       int c = add2(a, b);
    45 0040B796   mov         eax,dword ptr [ebp-8]
    46 0040B799   push        eax
    47 0040B79A   mov         ecx,dword ptr [ebp-4]
    48 0040B79D   push        ecx
    49 0040B79E   call        @ILT+5(add2) (0040100a)
    50 0040B7A3   add         esp,8
    51 0040B7A6   mov         dword ptr [ebp-0Ch],eax
    52 12:
    53 13:       return c;
    54 0040B7A9   mov         eax,dword ptr [ebp-0Ch]
    55 14:   }
    56 0040B7AC   pop         edi
    57 0040B7AD   pop         esi
    58 0040B7AE   pop         ebx
    59 0040B7AF   add         esp,4Ch
    60 0040B7B2   cmp         ebp,esp
    61 0040B7B4   call        __chkesp (0040b6b0)
    62 0040B7B9   mov         esp,ebp
    63 0040B7BB   pop         ebp
    64 0040B7BC   ret

    44行执行函数调用,过程如下:

    (1)参数入栈,从右向左;

    (2)CALL指令,注意CALL指令将EIP入栈,并JMP;

    (3)初始化ADD函数堆栈,push ebp; mov ebp, esp;sub esp,0x40; push ebx; push esi; push edi; rep stos ptr dword es:[edi].  rep指令表示,执行循环,循环次数放置在ECX寄存器中;stos指令表示,将EAX值放入edi指向的地址,并将edi递增.  在第10行我们看到EAX被设置为0xCCCCCCCC,所以rep stos ptr dword es:[edi]的作用是,将开辟的0x40局部变量空间初始化为0xCC,0xCC是INT 3的汇编指令,目的是防止误执行。

    (4)执行ADD指令,结果存放在EAX中;

    (5)恢复现场,pop ebx; pop esi; pop edi;

    (6)ret,弹出eip;

    (7)保持栈平衡,add esp,8;

    image

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  • 原文地址:https://www.cnblogs.com/yuqiao-ray-vision/p/3754448.html
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