I write a nothing.c, which is just one line as follows
int main(){}
Then I compile it using command gcc nothing.c -o nothing
Here's what I get using command readelf -x .text nothing
Hex dump of section '.text':
0x00001040 f30f1efa 31ed4989 d15e4889 e24883e4 ....1.I..^H..H..
0x00001050 f050544c 8d055601 0000488d 0ddf0000 .PTL..V...H.....
0x00001060 00488d3d c1000000 ff15722f 0000f490 .H.=......r/....
0x00001070 488d3d99 2f000048 8d05922f 00004839 H.=./..H.../..H9
0x00001080 f8741548 8b054e2f 00004885 c07409ff .t.H..N/..H..t..
0x00001090 e00f1f80 00000000 c30f1f80 00000000 ................
0x000010a0 488d3d69 2f000048 8d35622f 00004829 H.=i/..H.5b/..H)
0x000010b0 fe4889f0 48c1ee3f 48c1f803 4801c648 .H..H..?H...H..H
0x000010c0 d1fe7414 488b0525 2f000048 85c07408 ..t.H..%/..H..t.
0x000010d0 ffe0660f 1f440000 c30f1f80 00000000 ..f..D..........
0x000010e0 f30f1efa 803d252f 00000075 2b554883 .....=%/...u+UH.
0x000010f0 3d022f00 00004889 e5740c48 8b3d062f =./...H..t.H.=./
0x00001100 0000e829 ffffffe8 64ffffff c605fd2e ...)....d.......
0x00001110 0000015d c30f1f00 c30f1f80 00000000 ...]............
0x00001120 f30f1efa e977ffff fff30f1e fa554889 .....w.......UH.
0x00001130 e5b80000 00005dc3 0f1f8400 00000000 ......].........
0x00001140 f30f1efa 41574c8d 3da32c00 00415649 ....AWL.=.,..AVI
0x00001150 89d64155 4989f541 544189fc 55488d2d ..AUI..ATA..UH.-
0x00001160 942c0000 534c29fd 4883ec08 e88ffeff .,..SL).H.......
0x00001170 ff48c1fd 03741f31 db0f1f80 00000000 .H...t.1........
0x00001180 4c89f24c 89ee4489 e741ff14 df4883c3 L..L..D..A...H..
0x00001190 014839dd 75ea4883 c4085b5d 415c415d .H9.u.H...[]A\A]
0x000011a0 415e415f c366662e 0f1f8400 00000000 A^A_.ff.........
0x000011b0 f30f1efa c3 .....
So what does it do?
So what does it do?
You can see what it does:
objdump -d nothing
Disassembly of section .text:
0000000000001040 <_start>:
1040: 31 ed xor %ebp,%ebp
1042: 49 89 d1 mov %rdx,%r9
1045: 5e pop %rsi
1046: 48 89 e2 mov %rsp,%rdx
1049: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
104d: 50 push %rax
104e: 54 push %rsp
104f: 4c 8d 05 3a 01 00 00 lea 0x13a(%rip),%r8 # 1190 <__libc_csu_fini>
1056: 48 8d 0d d3 00 00 00 lea 0xd3(%rip),%rcx # 1130 <__libc_csu_init>
105d: 48 8d 3d c1 00 00 00 lea 0xc1(%rip),%rdi # 1125 <main>
1064: ff 15 76 2f 00 00 call *0x2f76(%rip) # 3fe0 <__libc_start_main@GLIBC_2.2.5>
106a: f4 hlt
106b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
0000000000001070 <deregister_tm_clones>:
1070: 48 8d 3d b1 2f 00 00 lea 0x2fb1(%rip),%rdi # 4028 <__TMC_END__>
1077: 48 8d 05 aa 2f 00 00 lea 0x2faa(%rip),%rax # 4028 <__TMC_END__>
... etc.