Linux下的进程虚拟内存结构是什么

这篇文章主要介绍"Linux下的进程虚拟内存结构是什么"，在日常操作中，相信很多人在Linux下的进程虚拟内存结构是什么问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答"Linux下的进程虚拟内存结构是什么"的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

PostgreSQL使用进程架构,每个连接对应一个后台进程,为了更好的理解这种架构,有必要深入理解进程的相关知识

一、虚拟内存

进程虚拟内存的详细结构如下图所示:

C样例程序如下:

#include #include #include /**                                                                                                       * f - print locations of various elements                                                                *                                                                                                        * Returns: nothing                                                                                       */void f(void)//子函数{     int a;     int b;     int c;     a = 98;     b = 1024;     c = a * b;     printf("[f] a = %d, b = %d, c = a * b = %d\n", a, b, c);     printf("[f] Adresses of a: %p, b = %p, c = %p\n", (void *)&a, (void *)&b, (void *)&c);}/**                                                                                                       * main - print locations of various elements                                                             *                                                                                                        * Return: EXIT_FAILURE if something failed. Otherwise EXIT_SUCCESS                                       */int main(int ac, char **av, char **env){     int a;//本地变量,位于栈中     void *p;//指针,在堆中分配内存     int i;     int size;     printf("Address of a: %p\n", (void *)&a);     p = malloc(98);//在堆中分配内存     if (p == NULL)     {          fprintf(stderr, "Can't malloc\n");          return (EXIT_FAILURE);     }     printf("Allocated space in the heap: %p\n", p);     printf("Address of function main: %p\n", (void *)main);//main函数所在的内存地址     printf("First bytes of the main function:\n\t");     for (i = 0; i < 15; i++)     {          printf("x ", ((unsigned char *)main)[i]);//首16个字节     }     printf("\n");     printf("Address of the array of arguments: %p\n", (void *)av);//输入参数数组地址     printf("Addresses of the arguments:\n\t");//     for (i = 0; i < ac; i++)     {          printf("[%s]:%p ", av[i], av[i]);//打印输入参数     }     printf("\n");     printf("Address of the array of environment variables: %p\n", (void *)env);//环境变量地址     printf("Address of the first environment variables:\n");//环境变量信息     for (i = 0; i < 3; i++)     {          printf("\t[%p]:\"%s\"\n", env[i], env[i]);     }     /* size of the env array */     i = 0;     while (env[i] != NULL)//以NULL作为终结     {          i++;     }     i++; /* the NULL pointer */     size = i * sizeof(char *);     printf("Size of the array env: %d elements -> %d bytes (0x%x)\n", i, size, size);//计算环境变量数组大小     f();//调用函数     getchar();//接受输入,进程不退出     return (EXIT_SUCCESS);}

编译并执行

[root@localhost hacker]# gcc -Wall -Wextra -Werror main-7.c -o 7[root@localhost hacker]# ./7 Hello Hacker Jack!Address of a: 0x7fff5b327bb8 --> 位于栈中Allocated space in the heap: 0x9b6010 --> 位于堆中Address of function main: 0x400729 --> 可执行文件First bytes of the main function:    55 48 89 e5 48 83 ec 40 89 7d dc 48 89 75 d0 Address of the array of arguments: 0x7fff5b327cb8 -->参数数组地址Addresses of the arguments:    [./7]:0x7fff5b329808 [Hello]:0x7fff5b32980c [Hacker]:0x7fff5b329812 [Jack!]:0x7fff5b329819 --> 输入参数Address of the array of environment variables: 0x7fff5b327ce0 --> 环境变量数组Address of the first environment variables:    [0x7fff5b32981f]:"XDG_SESSION_ID=1"    [0x7fff5b329830]:"HOSTNAME=localhost.localdomain"    [0x7fff5b32984f]:"SELINUX_ROLE_REQUESTED="Size of the array env: 27 elements -> 216 bytes (0xd8)[f] a = 98, b = 1024, c = a * b = 100352 [f] Adresses of a: 0x7fff5b327b7c, b = 0x7fff5b327b78, c = 0x7fff5b327b74 --> 函数f中的变量地址

通过udis86可反编译,得到汇编代码

[root@localhost install]#  echo "55 48 89 e5 48 83 ec 10 48 8d 45 f0 48 89 c6" | udcli -64 -x -o 4007290000000000400729 55               push rbp                000000000040072a 4889e5           mov rbp, rsp            000000000040072d 4883ec10         sub rsp, 0x10           0000000000400731 488d45f0         lea rax, [rbp-0x10]     0000000000400735 4889c6           mov rsi, rax            [root@localhost install]#

查看该进程的内存映射信息

[root@localhost install]# ps aux | grep "./7" | grep -v greproot      6471  0.0  0.0   4348   348 pts/0    S+   15:24   0:00 ./7 Hello Hacker Jack![root@localhost install]# cat /proc/6471/maps00400000-00401000 r-xp 00000000 fd:00 134287606                          /data/source/hacker/700600000-00601000 r--p 00000000 fd:00 134287606                          /data/source/hacker/700601000-00602000 rw-p 00001000 fd:00 134287606                          /data/source/hacker/7009b6000-009d7000 rw-p 00000000 00:00 0                                  [heap]7f95b5d16000-7f95b5ed8000 r-xp 00000000 fd:00 151914                     /usr/lib64/libc-2.17.so7f95b5ed8000-7f95b60d8000 ---p 001c2000 fd:00 151914                     /usr/lib64/libc-2.17.so7f95b60d8000-7f95b60dc000 r--p 001c2000 fd:00 151914                     /usr/lib64/libc-2.17.so7f95b60dc000-7f95b60de000 rw-p 001c6000 fd:00 151914                     /usr/lib64/libc-2.17.so7f95b60de000-7f95b60e3000 rw-p 00000000 00:00 0 7f95b60e3000-7f95b6105000 r-xp 00000000 fd:00 151907                     /usr/lib64/ld-2.17.so7f95b62f8000-7f95b62fb000 rw-p 00000000 00:00 0 7f95b6301000-7f95b6304000 rw-p 00000000 00:00 0 7f95b6304000-7f95b6305000 r--p 00021000 fd:00 151907                     /usr/lib64/ld-2.17.so7f95b6305000-7f95b6306000 rw-p 00022000 fd:00 151907                     /usr/lib64/ld-2.17.so7f95b6306000-7f95b6307000 rw-p 00000000 00:00 0 7fff5b309000-7fff5b32a000 rw-p 00000000 00:00 0                          [stack]7fff5b3f1000-7fff5b3f3000 r-xp 00000000 00:00 0                          [vdso]ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall][root@localhost install]#

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