RVOS练习3-1

RVOS

编写一个简单的打印”hello world!”的程序文件：hello.c

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#include <stdio.h>
void main()
{
    printf("hello world!\n");
    return;
}

对源文件进行本地编译，生成针对支持 x86_64 指令集架构处理器的目标文件 hello.o

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gcc -g -o hello.c

查看hello.o的文件的文件头信息

hello.o的文件头信息可使用如下指令查看: 

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readelf -h hello.o

输出如下:

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ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          2080 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           64 (bytes)
  Number of section headers:         23
  Section header string table index: 22

对 hello.o 反汇编，并查看 hello.c 的 C 程序源码和机器指令的对应关系

使用以下指令对hello.o进行反汇编： 

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objdump -S hello.o

输出如下：

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hello.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <main>:
#include <stdio.h>
void main()
{
   0:   f3 0f 1e fa             endbr64 
   4:   55                      push   %rbp
   5:   48 89 e5                mov    %rsp,%rbp
    printf("hello world!\n");
   8:   48 8d 05 00 00 00 00    lea    0x0(%rip),%rax        # f <main+0xf>
   f:   48 89 c7                mov    %rax,%rdi
  12:   e8 00 00 00 00          call   17 <main+0x17>
    return;
  17:   90                      nop
}
  18:   5d                      pop    %rbp
  19:   c3                      ret