2021年09月13日 | jz2440裸机开发与分析： 点亮LED灯之C语言2

   c: e1a0c00d mov ip, sp                         //ip = 4096

  10: e92dd800 stmdb sp!, {fp, ip, lr, pc}      //分析见下图

  14: e24cb004 sub fp, ip, #4 ; 0x4              //fp = 4092

  18: e24dd008 sub sp, sp, #8 ; 0x8              //sp = 4088

  1c: e3a03456 mov r3, #1442840576 ; 0x56000000   //r3 = 0x56000000

  20: e2833050 add r3, r3, #80 ; 0x50             //r3 = 0x56000050

  24: e50b3010 str r3, [fp, #-16]       //地址fp（4092）-16 = 4076 存入0x56000050是c语言unsigned int *pGPFCON = (unsigned int *)0x56000050;

  28: e3a03456 mov r3, #1442840576 ; 0x56000000

  2c: e2833054 add r3, r3, #84 ; 0x54

  30: e50b3014 str r3, [fp, #-20]     

  34: e51b2010 ldr r2, [fp, #-16]

  38: e3a03c01 mov r3, #256 ; 0x100

  3c: e5823000 str r3, [r2]                       //和上同理地址4072存入0x100

  40: e51b2014 ldr r2, [fp, #-20]

  44: e3a03000 mov r3, #0 ; 0x0

  48: e5823000 str r3, [r2]                      //*pGPFDAT = 0;

  4c: e3a03000 mov r3, #0 ; 0x0            //return 0;

  50: e1a00003 mov r0, r3

  54: e24bd00c sub sp, fp, #12 ; 0xc

  58: e89da800 ldmia sp, {fp, sp, pc}    //分析见下图

Disassembly of section .comment:

00000000 <.comment>:

   0: 43434700 cmpmi r3, #0 ; 0x0

   4: 4728203a undefined

   8: 2029554e eorcs r5, r9, lr, asr #10

   c: 2e342e33 mrccs 14, 1, r2, cr4, cr3, {1}

  10: Address 0x10 is out of bounds.

第10行分析

第58行分析（最终sp=4096 pc = 8 成功执行完主函数）

栈：就是sp指向的内存可读可写