c语言中函数名代表函数地址，那函数的大小（就是函数指令在内存中的字节数）怎么求

在}

int main(int arg, void *args[])
{
test();
return 0;
}
编译命令gcc -o test test.c 生成test可执行文件。
用readelf -s test命令可以读出test文件里面的各个段的大小。
Symbol table '.dynsym' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 401 FUNC GLOBAL DEFAULT UND puts@GLIBC_2.0 (2)
2: 00000000 391 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.0 (2)
3: 0804845c 4 OBJECT GLOBAL DEFAULT 14 _IO_stdin_used
4: 00000000 0 NOTYPE WEAK DEFAULT UND _Jv_RegisterClasses
5: 00000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__

Symbol table '.symtab' contains 71 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 08048114 0 SECTION LOCAL DEFAULT 1
2: 08048128 0 SECTION LOCAL DEFAULT 2
3: 08048148 0 SECTION LOCAL DEFAULT 3
4: 08048174 0 SECTION LOCAL DEFAULT 4
5: 080481d4 0 SECTION LOCAL DEFAULT 5
6: 08048232 0 SECTION LOCAL DEFAULT 6
7: 08048240 0 SECTION LOCAL DEFAULT 7
8: 08048260 0 SECTION LOCAL DEFAULT 8
9: 08048268 0 SECTION LOCAL DEFAULT 9
10: 08048280 0 SECTION LOCAL DEFAULT 10
11: 08048298 0 SECTION LOCAL DEFAULT 11
12: 080482d8 0 SECTION LOCAL DEFAULT 12
13: 0804843c 0 SECTION LOCAL DEFAULT 13
14: 08048458 0 SECTION LOCAL DEFAULT 14
15: 08048468 0 SECTION LOCAL DEFAULT 15
16: 0804946c 0 SECTION LOCAL DEFAULT 16
17: 08049474 0 SECTION LOCAL DEFAULT 17
18: 0804947c 0 SECTION LOCAL DEFAULT 18
19: 08049480 0 SECTION LOCAL DEFAULT 19
20: 08049548 0 SECTION LOCAL DEFAULT 20
21: 0804954c 0 SECTION LOCAL DEFAULT 21
22: 08049564 0 SECTION LOCAL DEFAULT 22
23: 08049570 0 SECTION LOCAL DEFAULT 23
24: 00000000 0 SECTION LOCAL DEFAULT 24
25: 00000000 0 SECTION LOCAL DEFAULT 25
26: 00000000 0 SECTION LOCAL DEFAULT 26
27: 00000000 0 SECTION LOCAL DEFAULT 27
28: 080482fc 0 FUNC LOCAL DEFAULT 12 call_gmon_start
29: 00000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
30: 0804946c 0 OBJECT LOCAL DEFAULT 16 __CTOR_LIST__
31: 08049474 0 OBJECT LOCAL DEFAULT 17 __DTOR_LIST__
32: 0804947c 0 OBJECT LOCAL DEFAULT 18 __JCR_LIST__
33: 08049570 1 OBJECT LOCAL DEFAULT 23 completed.4583
34: 0804956c 0 OBJECT LOCAL DEFAULT 22 p.4582
35: 08048320 0 FUNC LOCAL DEFAULT 12 __do_global_dtors_aux
36: 08048354 0 FUNC LOCAL DEFAULT 12 frame_dummy
37: 00000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
38: 08049470 0 OBJECT LOCAL DEFAULT 16 __CTOR_END__
39: 08049478 0 OBJECT LOCAL DEFAULT 17 __DTOR_END__
40: 08048468 0 OBJECT LOCAL DEFAULT 15 __FRAME_END__
41: 0804947c 0 OBJECT LOCAL DEFAULT 18 __JCR_END__
42: 08048414 0 FUNC LOCAL DEFAULT 12 __do_global_ctors_aux
43: 00000000 0 FILE LOCAL DEFAULT ABS test.c
44: 08049480 0 OBJECT GLOBAL DEFAULT 19 _DYNAMIC
45: 08048458 4 OBJECT GLOBAL DEFAULT 14 _fp_hw
46: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __fini_array_end
47: 08049568 0 OBJECT GLOBAL HIDDEN 22 __dso_handle
48: 0804840c 5 FUNC GLOBAL DEFAULT 12 __libc_csu_fini
49: 00000000 401 FUNC GLOBAL DEFAULT UND puts@@GLIBC_2.0
50: 08048280 0 FUNC GLOBAL DEFAULT 10 _init
51: 0804837c 24 FUNC GLOBAL DEFAULT 12 test
52: 080482d8 0 FUNC GLOBAL DEFAULT 12 _start
53: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __fini_array_start
54: 080483bc 79 FUNC GLOBAL DEFAULT 12 __libc_csu_init
55: 08049570 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
56: 08048394 40 FUNC GLOBAL DEFAULT 12 main
57: 00000000 391 FUNC GLOBAL DEFAULT UND __libc_start_main@@GLIBC_
58: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __init_array_end
59: 08049564 0 NOTYPE WEAK DEFAULT 22 data_start
60: 0804843c 0 FUNC GLOBAL DEFAULT 13 _fini
61: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __preinit_array_end
62: 08049570 0 NOTYPE GLOBAL DEFAULT ABS _edata
63: 0804954c 0 OBJECT GLOBAL HIDDEN 21 _GLOBAL_OFFSET_TABLE_
64: 08049574 0 NOTYPE GLOBAL DEFAULT ABS _end
65: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __init_array_start
66: 0804845c 4 OBJECT GLOBAL DEFAULT 14 _IO_stdin_used
67: 08049564 0 NOTYPE GLOBAL DEFAULT 22 __data_start
68: 00000000 0 NOTYPE WEAK DEFAULT UND _Jv_RegisterClasses
69: 0804946c 0 NOTYPE GLOBAL HIDDEN ABS __preinit_array_start
70: 00000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
其中，
51: 0804837c 24 FUNC GLOBAL DEFAULT 12 test
这行0804837c就是test（）函数的起始地址，24就是test（）函数的指令静态存储空间。