ld 链接出来的可执行文件无法被执行？提示 No such file or directory

[movq]

这是我的两个源代码文件

//main.c
#include "stdio.h"
int sum(int *a, int n);

int array[2] = {1, 2};

int main()
{
        int val = sum(array,2);
        printf("%d\n", val);
        return 0;
}

//sum.c
int sum(int *a, int n)
{
        int i=0,s =0;
        for(;i<n;i++)
                s+=a[i];
        return s;
}

通过以下步骤生成可执行文件：

# preprocessing
gcc -E main.c -o main.i 
gcc -E sum.c -o sum.i

# compilation
gcc -Og -S main.i -o main.s 
gcc -Og -S sum.i -o sum.s

# assembling
as main.s -o main.o
as sum.s -o sum.o

# linking
ld -o prog sum.o main.o -lc --entry main

但是生成的可执行文件运行不了：

$ ./prog
-bash: ./prog: No such file or directory

$ file ./prog
prog: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib/ld6, not stripped

$ stat prog
  File: prog
  Size: 6424      	Blocks: 16         IO Block: 4096   regular file
Device: 801h/2049d	Inode: 3153139     Links: 1
Access: (0777/-rwxrwxrwx)  Uid: ( 1000/       u)   Gid: ( 1000/       u)
Access: 2021-01-22 17:41:02.516854257 +0800
Modify: 2021-01-22 17:31:02.969230783 +0800
Change: 2021-01-22 17:40:57.432364965 +0800
 Birth: -

我使用的操作系统是 ubuntu 18.04 x86-64

[azenk]

readelf -s

[movq]

@azenk

Symbol table '.symtab' contains 13 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000004000e8 0 SECTION LOCAL DEFAULT 1
2: 0000000000400150 0 SECTION LOCAL DEFAULT 2
3: 0000000000601000 0 SECTION LOCAL DEFAULT 3
4: 0000000000000000 0 SECTION LOCAL DEFAULT 4
5: 0000000000000000 0 FILE LOCAL DEFAULT ABS main.c
6: 0000000000000000 0 FILE LOCAL DEFAULT ABS sum.c
7: 0000000000400109 69 FUNC GLOBAL DEFAULT 1 sum
8: 0000000000601008 0 NOTYPE GLOBAL DEFAULT 3 __bss_start
9: 00000000004000e8 33 FUNC GLOBAL DEFAULT 1 main
10: 0000000000601000 8 OBJECT GLOBAL DEFAULT 3 array
11: 0000000000601008 0 NOTYPE GLOBAL DEFAULT 3 _edata
12: 0000000000601008 0 NOTYPE GLOBAL DEFAULT 3 _end

[katsusan]

strace -t ./prog

[hello2060]

[21:54:50] ~ $ man ld
[21:56:50] ~ $ ld -o prog sum.o main.o -lc -e main
Undefined symbols for architecture x86_64:
"main", referenced from:
implicit entry/start for main executable
(maybe you meant: _main)
ld: symbol(s) not found for architecture x86_64
[21:57:20] ~ $ ld -o prog sum.o main.o -lc -e _mai
[21:57:34] ~ $ ./prog
3


我在 mac 上的结果，

[XiaoxiaoPu]

动态链接 C 库需要额外配置，参考

stackoverflow.com/questions/3577922/how-to-link-a-gas-assembly-program-that-uses-the-c-standard-library-with-ld-with

[movq]

`ldd prog`
查看到` /lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2.`

`/lib/ld64.so.1` 不存在

所以在 ld 链接时添加`--dynamic-linker=/lib64/ld-linux-x86-64.so.2`这个选项，链接出来的 prog 可以执行

但是执行结果是

```
3
Segmentation fault (core dumped)
```

有点好奇为什么会出现`Segmentation fault (core dumped)`

[movq]

解决了，gcc 调用 ld 的时候会自动传入很多参数，可以通过 gcc -v 来查看到底传了什么参数

把这些参数复制然后手动传给 ld，就正常了