asmexamples

[root@centos7 aarch64-bare-metal-qemu]# cat libc.s 
/*
Output "Hello world!" to standard output.
For Aarch64 (ARM64) architecture with GNU assembler, using Linux libc functions.

Assemble with :
as -o hello.o hello.aarch64.linux.libc.gas.asm &&
gcc -o hello hello.o
*/

.global main
.section .text
.balign 4

main:
        stp  x29, x30, [sp, -16]!
        add  x29, sp, 0
        adrp x0, message
        add  x0, x0, :lo12:message
        bl   printf
        mov  w0, 0
        ldp  x29, x30, [sp], 16
        ret

.section .rodata
.balign 4

message:
        .asciz "Hello world!\n\0"

"libc.s" [New] 28L, 473C written                                                                                                                                                                                                              
[root@centos7 aarch64-bare-metal-qemu]# as -o hello.o libc.s
[root@centos7 aarch64-bare-metal-qemu]# gcc -o hello hello.o
[root@centos7 aarch64-bare-metal-qemu]# ./hello
Hello world!
[root@centos7 aarch64-bare-metal-qemu]# 

[root@centos7 aarch64-bare-metal-qemu]# ld  hello.o -o hello
ld: warning: cannot find entry symbol _start; defaulting to 0000000000400078
hello.o: In function `main':
(.text+0x10): undefined reference to `printf'

[root@centos7 aarch64-bare-metal-qemu]# gcc -o hello hello.o
[root@centos7 aarch64-bare-metal-qemu]# objdump -s -d hello > hello.txt
[root@centos7 aarch64-bare-metal-qemu]# cat hello.txt 

hello:     file format elf64-littleaarch64

Contents of section .interp:
 400238 2f6c6962 2f6c642d 6c696e75 782d6161  /lib/ld-linux-aa
 400248 72636836 342e736f 2e3100             rch64.so.1.     
Contents of section .note.ABI-tag:
 400254 04000000 10000000 01000000 474e5500  ............GNU.
 400264 00000000 03000000 07000000 00000000  ................
Contents of section .note.gnu.build-id:
 400274 04000000 14000000 03000000 474e5500  ............GNU.
 400284 26121295 64b374d0 4920ed05 08b6775a  &...d.t.I ....wZ
 400294 ecd5f11f                             ....            
Contents of section .gnu.hash:
 400298 03000000 02000000 01000000 06000000  ................
 4002a8 00000000 00402021 00000000 02000000  .....@ !........
 4002b8 04000000 7ced110f b92b6b15 2f4e3df6  ....|....+k./N=.
Contents of section .dynsym:
 4002c8 00000000 00000000 00000000 00000000  ................
 4002d8 00000000 00000000 2a000000 20000000  ........*... ...
 4002e8 00000000 00000000 00000000 00000000  ................
 4002f8 0b000000 12000000 00000000 00000000  ................
 400308 00000000 00000000 11000000 12000000  ................
 400318 00000000 00000000 00000000 00000000  ................
 400328 18000000 12000000 00000000 00000000  ................
 400338 00000000 00000000                    ........        
Contents of section .dynstr:
 400340 006c6962 632e736f 2e360061 626f7274  .libc.so.6.abort
 400350 00707269 6e746600 5f5f6c69 62635f73  .printf.__libc_s
 400360 74617274 5f6d6169 6e005f5f 676d6f6e  tart_main.__gmon
 400370 5f737461 72745f5f 00474c49 42435f32  _start__.GLIBC_2
 400380 2e313700                             .17.            
Contents of section .gnu.version:
 400384 00000000 02000200 0200               ..........      
Contents of section .gnu.version_r:
 400390 01000100 01000000 10000000 00000000  ................
 4003a0 97919606 00000200 39000000 00000000  ........9.......
Contents of section .rela.dyn:
 4003b0 e0ff4100 00000000 01040000 01000000  ..A.............
 4003c0 00000000 00000000                    ........        
Contents of section .rela.plt:
 4003c8 00004200 00000000 02040000 04000000  ..B.............
 4003d8 00000000 00000000 08004200 00000000  ..........B.....
 4003e8 02040000 01000000 00000000 00000000  ................
 4003f8 10004200 00000000 02040000 02000000  ..B.............
 400408 00000000 00000000 18004200 00000000  ..........B.....
 400418 02040000 03000000 00000000 00000000  ................
Contents of section .init:
 400428 fd7bbfa9 fd030091 2e000094 fd7bc1a8  .{...........{..
 400438 c0035fd6                             .._.            
Contents of section .plt:
 400440 f07bbfa9 f00000f0 11fe47f9 10e23f91  .{........G...?.
 400450 20021fd6 1f2003d5 1f2003d5 1f2003d5   .... ... ... ..
 400460 10010090 110240f9 10020091 20021fd6  ......@..... ...
 400470 10010090 110640f9 10220091 20021fd6  ......@..".. ...
 400480 10010090 110a40f9 10420091 20021fd6  ......@..B.. ...
 400490 10010090 110e40f9 10620091 20021fd6  ......@..b.. ...
Contents of section .text:
 4004a0 1d0080d2 1e0080d2 fd030091 e50300aa  ................
 4004b0 e10340f9 e2230091 e6030091 a0000058  ..@..#.........X
 4004c0 c3000058 e4000058 e6ffff97 edffff97  ...X...X........
 4004d0 00064000 00000000 20064000 00000000  ..@..... .@.....
 4004e0 98064000 00000000 e00000f0 00f047f9  ..@...........G.
 4004f0 400000b4 dfffff17 c0035fd6 00000000  @........._.....
 400500 01010090 00010090 21a00091 fd7bbfa9  ........!....{..
 400510 00a00091 211c0091 fd030091 210000cb  ....!.......!...
 400520 3f3800f1 68000054 fd7bc1a8 c0035fd6  ?8..h..T.{...._.
 400530 81000058 a1ffffb4 20003fd6 fbffff17  ...X.... .?.....
 400540 00000000 00000000 00010090 01010090  ................
 400550 00a00091 21a00091 210000cb fd7bbfa9  ....!...!....{..
 400560 21fc4393 fd030091 21fc418b 21fc4193  !.C.....!.A.!.A.
 400570 610000b5 fd7bc1a8 c0035fd6 a2000058  a....{...._....X
 400580 a2ffffb4 40003fd6 fbffff17 1f2003d5  ....@.?...... ..
 400590 00000000 00000000 fd7bbea9 fd030091  .........{......
 4005a0 f30b00f9 13010090 60924039 80000035  ........`.@9...5
 4005b0 d4ffff97 20008052 60920039 f30b40f9  .... ..R`..9..@.
 4005c0 fd7bc2a8 c0035fd6 fd7bbfa9 fd030091  .{...._..{......
 4005d0 e00000f0 010047f9 00003891 810000b4  ......G...8.....
 4005e0 c1000058 410000b4 20003fd6 fd7bc1a8  ...XA... .?..{..
 4005f0 d6ffff17 1f2003d5 00000000 00000000  ..... ..........
 400600 fd7bbfa9 fd030091 00000090 00001b91  .{..............
 400610 a0ffff97 00008052 fd7bc1a8 c0035fd6  .......R.{...._.
 400620 fd7bbca9 fd030091 f35301a9 f76303a9  .{.......S...c..
 400630 f40000f0 f80000f0 18c33791 94e23791  ..........7...7.
 400640 940218cb 94fe4393 f55b02a9 f703002a  ......C..[.....*
 400650 f60301aa f50302aa 130080d2 73ffff97  ............s...
 400660 340100b4 037b73f8 e003172a e10316aa  4....{s....*....
 400670 e20315aa 60003fd6 73060091 7f0214eb  ....`.?.s.......
 400680 21ffff54 f35341a9 f55b42a9 f76343a9  !..T.SA..[B..cC.
 400690 fd7bc4a8 c0035fd6 c0035fd6           .{...._..._.    
Contents of section .fini:
 40069c fd7bbfa9 fd030091 fd7bc1a8 c0035fd6  .{.......{...._.
Contents of section .rodata:
 4006b0 01000200 00000000 00000000 00000000  ................
 4006c0 48656c6c 6f20776f 726c6421 0a0000    Hello world!... 
Contents of section .eh_frame_hdr:
 4006d0 011b033b 3c000000 06000000 30feffff  ...;<.......0...
 4006e0 58000000 78feffff 80000000 c8feffff  X...x...........
 4006f0 a8000000 f8feffff d0000000 50ffffff  ............P...
 400700 f8000000 c8ffffff 30010000           ........0...    
Contents of section .eh_frame:
 400710 14000000 00000000 017a5200 04781e01  .........zR..x..
 400720 1b0c1f00 00000000 24000000 1c000000  ........$.......
 400730 d0fdffff 40000000 00440e10 9d029e01  ....@....D......
 400740 430d1d44 0adedd0c 1f00410b 00000000  C..D......A.....
 400750 24000000 44000000 f0fdffff 44000000  $...D.......D...
 400760 00460e10 9d029e01 420d1d44 0adedd0c  .F......B..D....
 400770 1f00410b 00000000 24000000 6c000000  ..A.....$...l...
 400780 18feffff 30000000 00410e20 9d049e03  ....0....A. ....
 400790 410d1d41 930248de ddd30c1f 00000000  A..A..H.........
 4007a0 24000000 94000000 20feffff 2c000000  $....... ...,...
 4007b0 00410e10 9d029e01 410d1d48 dedd0c1f  .A......A..H....
 4007c0 00000000 00000000 34000000 bc000000  ........4.......
 4007d0 50feffff 78000000 00410e40 9d089e07  P...x....A.@....
 4007e0 410d1d42 93069405 97029801 47950496  A..B........G...
 4007f0 0352dedd d8d7d6d5 d4d30c1f 00000000  .R..............
 400800 14000000 f4000000 90feffff 04000000  ................
 400810 00000000 00000000 00000000           ............    
Contents of section .init_array:
 41fdf0 c8054000 00000000                    ..@.....        
Contents of section .fini_array:
 41fdf8 98054000 00000000                    ..@.....        
Contents of section .jcr:
 41fe00 00000000 00000000                    ........        
Contents of section .dynamic:
 41fe08 01000000 00000000 01000000 00000000  ................
 41fe18 0c000000 00000000 28044000 00000000  ........(.@.....
 41fe28 0d000000 00000000 9c064000 00000000  ..........@.....
 41fe38 19000000 00000000 f0fd4100 00000000  ..........A.....
 41fe48 1b000000 00000000 08000000 00000000  ................
 41fe58 1a000000 00000000 f8fd4100 00000000  ..........A.....
 41fe68 1c000000 00000000 08000000 00000000  ................
 41fe78 f5feff6f 00000000 98024000 00000000  ...o......@.....
 41fe88 05000000 00000000 40034000 00000000  ........@.@.....
 41fe98 06000000 00000000 c8024000 00000000  ..........@.....
 41fea8 0a000000 00000000 44000000 00000000  ........D.......
 41feb8 0b000000 00000000 18000000 00000000  ................
 41fec8 15000000 00000000 00000000 00000000  ................
 41fed8 03000000 00000000 e8ff4100 00000000  ..........A.....
 41fee8 02000000 00000000 60000000 00000000  ........`.......
 41fef8 14000000 00000000 07000000 00000000  ................
 41ff08 17000000 00000000 c8034000 00000000  ..........@.....
 41ff18 07000000 00000000 b0034000 00000000  ..........@.....
 41ff28 08000000 00000000 18000000 00000000  ................
 41ff38 09000000 00000000 18000000 00000000  ................
 41ff48 feffff6f 00000000 90034000 00000000  ...o......@.....
 41ff58 ffffff6f 00000000 01000000 00000000  ...o............
 41ff68 f0ffff6f 00000000 84034000 00000000  ...o......@.....
 41ff78 00000000 00000000 00000000 00000000  ................
 41ff88 00000000 00000000 00000000 00000000  ................
 41ff98 00000000 00000000 00000000 00000000  ................
 41ffa8 00000000 00000000 00000000 00000000  ................
 41ffb8 00000000 00000000 00000000 00000000  ................
 41ffc8 00000000 00000000 00000000 00000000  ................
Contents of section .got:
 41ffd8 08fe4100 00000000 00000000 00000000  ..A.............
Contents of section .got.plt:
 41ffe8 00000000 00000000 00000000 00000000  ................
 41fff8 00000000 00000000 40044000 00000000  ........@.@.....
 420008 40044000 00000000 40044000 00000000  @.@.....@.@.....
 420018 40044000 00000000                    @.@.....        
Contents of section .data:
 420020 00000000                             ....            
Contents of section .comment:
 0000 4743433a 2028474e 55292034 2e382e35  GCC: (GNU) 4.8.5
 0010 20323031 35303632 33202852 65642048   20150623 (Red H
 0020 61742034 2e382e35 2d343429 00        at 4.8.5-44).   

Disassembly of section .init:

0000000000400428 <_init>:
  400428:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  40042c:       910003fd        mov     x29, sp
  400430:       9400002e        bl      4004e8 <call_weak_fn>
  400434:       a8c17bfd        ldp     x29, x30, [sp],#16
  400438:       d65f03c0        ret

Disassembly of section .plt:

0000000000400440 <.plt>:
  400440:       a9bf7bf0        stp     x16, x30, [sp,#-16]!
  400444:       f00000f0        adrp    x16, 41f000 <__FRAME_END__+0x1e7e8>
  400448:       f947fe11        ldr     x17, [x16,#4088]
  40044c:       913fe210        add     x16, x16, #0xff8
  400450:       d61f0220        br      x17
  400454:       d503201f        nop
  400458:       d503201f        nop
  40045c:       d503201f        nop

0000000000400460 <__libc_start_main@plt>:
  400460:       90000110        adrp    x16, 420000 <__libc_start_main@GLIBC_2.17>
  400464:       f9400211        ldr     x17, [x16]
  400468:       91000210        add     x16, x16, #0x0
  40046c:       d61f0220        br      x17

0000000000400470 <__gmon_start__@plt>:
  400470:       90000110        adrp    x16, 420000 <__libc_start_main@GLIBC_2.17>
  400474:       f9400611        ldr     x17, [x16,#8]
  400478:       91002210        add     x16, x16, #0x8
  40047c:       d61f0220        br      x17

0000000000400480 <abort@plt>:
  400480:       90000110        adrp    x16, 420000 <__libc_start_main@GLIBC_2.17>
  400484:       f9400a11        ldr     x17, [x16,#16]
  400488:       91004210        add     x16, x16, #0x10
  40048c:       d61f0220        br      x17

0000000000400490 <printf@plt>:
  400490:       90000110        adrp    x16, 420000 <__libc_start_main@GLIBC_2.17>
  400494:       f9400e11        ldr     x17, [x16,#24]
  400498:       91006210        add     x16, x16, #0x18
  40049c:       d61f0220        br      x17

Disassembly of section .text:

00000000004004a0 <_start>:
  4004a0:       d280001d        mov     x29, #0x0                       // #0
  4004a4:       d280001e        mov     x30, #0x0                       // #0
  4004a8:       910003fd        mov     x29, sp
  4004ac:       aa0003e5        mov     x5, x0
  4004b0:       f94003e1        ldr     x1, [sp]
  4004b4:       910023e2        add     x2, sp, #0x8
  4004b8:       910003e6        mov     x6, sp
  4004bc:       580000a0        ldr     x0, 4004d0 <_start+0x30>
  4004c0:       580000c3        ldr     x3, 4004d8 <_start+0x38>
  4004c4:       580000e4        ldr     x4, 4004e0 <_start+0x40>
  4004c8:       97ffffe6        bl      400460 <__libc_start_main@plt>
  4004cc:       97ffffed        bl      400480 <abort@plt>
  4004d0:       00400600        .word   0x00400600
  4004d4:       00000000        .word   0x00000000
  4004d8:       00400620        .word   0x00400620
  4004dc:       00000000        .word   0x00000000
  4004e0:       00400698        .word   0x00400698
  4004e4:       00000000        .word   0x00000000

00000000004004e8 <call_weak_fn>:
  4004e8:       f00000e0        adrp    x0, 41f000 <__FRAME_END__+0x1e7e8>
  4004ec:       f947f000        ldr     x0, [x0,#4064]
  4004f0:       b4000040        cbz     x0, 4004f8 <call_weak_fn+0x10>
  4004f4:       17ffffdf        b       400470 <__gmon_start__@plt>
  4004f8:       d65f03c0        ret
  4004fc:       00000000        .inst   0x00000000 ; undefined

0000000000400500 <deregister_tm_clones>:
  400500:       90000101        adrp    x1, 420000 <__libc_start_main@GLIBC_2.17>
  400504:       90000100        adrp    x0, 420000 <__libc_start_main@GLIBC_2.17>
  400508:       9100a021        add     x1, x1, #0x28
  40050c:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  400510:       9100a000        add     x0, x0, #0x28
  400514:       91001c21        add     x1, x1, #0x7
  400518:       910003fd        mov     x29, sp
  40051c:       cb000021        sub     x1, x1, x0
  400520:       f100383f        cmp     x1, #0xe
  400524:       54000068        b.hi    400530 <deregister_tm_clones+0x30>
  400528:       a8c17bfd        ldp     x29, x30, [sp],#16
  40052c:       d65f03c0        ret
  400530:       58000081        ldr     x1, 400540 <deregister_tm_clones+0x40>
  400534:       b4ffffa1        cbz     x1, 400528 <deregister_tm_clones+0x28>
  400538:       d63f0020        blr     x1
  40053c:       17fffffb        b       400528 <deregister_tm_clones+0x28>
        ...

0000000000400548 <register_tm_clones>:
  400548:       90000100        adrp    x0, 420000 <__libc_start_main@GLIBC_2.17>
  40054c:       90000101        adrp    x1, 420000 <__libc_start_main@GLIBC_2.17>
  400550:       9100a000        add     x0, x0, #0x28
  400554:       9100a021        add     x1, x1, #0x28
  400558:       cb000021        sub     x1, x1, x0
  40055c:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  400560:       9343fc21        asr     x1, x1, #3
  400564:       910003fd        mov     x29, sp
  400568:       8b41fc21        add     x1, x1, x1, lsr #63
  40056c:       9341fc21        asr     x1, x1, #1
  400570:       b5000061        cbnz    x1, 40057c <register_tm_clones+0x34>
  400574:       a8c17bfd        ldp     x29, x30, [sp],#16
  400578:       d65f03c0        ret
  40057c:       580000a2        ldr     x2, 400590 <register_tm_clones+0x48>
  400580:       b4ffffa2        cbz     x2, 400574 <register_tm_clones+0x2c>
  400584:       d63f0040        blr     x2
  400588:       17fffffb        b       400574 <register_tm_clones+0x2c>
  40058c:       d503201f        nop
        ...

0000000000400598 <__do_global_dtors_aux>:
  400598:       a9be7bfd        stp     x29, x30, [sp,#-32]!
  40059c:       910003fd        mov     x29, sp
  4005a0:       f9000bf3        str     x19, [sp,#16]
  4005a4:       90000113        adrp    x19, 420000 <__libc_start_main@GLIBC_2.17>
  4005a8:       39409260        ldrb    w0, [x19,#36]
  4005ac:       35000080        cbnz    w0, 4005bc <__do_global_dtors_aux+0x24>
  4005b0:       97ffffd4        bl      400500 <deregister_tm_clones>
  4005b4:       52800020        mov     w0, #0x1                        // #1
  4005b8:       39009260        strb    w0, [x19,#36]
  4005bc:       f9400bf3        ldr     x19, [sp,#16]
  4005c0:       a8c27bfd        ldp     x29, x30, [sp],#32
  4005c4:       d65f03c0        ret

00000000004005c8 <frame_dummy>:
  4005c8:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  4005cc:       910003fd        mov     x29, sp
  4005d0:       f00000e0        adrp    x0, 41f000 <__FRAME_END__+0x1e7e8>
  4005d4:       f9470001        ldr     x1, [x0,#3584]
  4005d8:       91380000        add     x0, x0, #0xe00
  4005dc:       b4000081        cbz     x1, 4005ec <frame_dummy+0x24>
  4005e0:       580000c1        ldr     x1, 4005f8 <frame_dummy+0x30>
  4005e4:       b4000041        cbz     x1, 4005ec <frame_dummy+0x24>
  4005e8:       d63f0020        blr     x1
  4005ec:       a8c17bfd        ldp     x29, x30, [sp],#16
  4005f0:       17ffffd6        b       400548 <register_tm_clones>
  4005f4:       d503201f        nop
        ...

0000000000400600 <main>:
  400600:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  400604:       910003fd        mov     x29, sp
  400608:       90000000        adrp    x0, 400000 <_init-0x428>
  40060c:       911b0000        add     x0, x0, #0x6c0
  400610:       97ffffa0        bl      400490 <printf@plt>
  400614:       52800000        mov     w0, #0x0                        // #0
  400618:       a8c17bfd        ldp     x29, x30, [sp],#16
  40061c:       d65f03c0        ret

0000000000400620 <__libc_csu_init>:
  400620:       a9bc7bfd        stp     x29, x30, [sp,#-64]!
  400624:       910003fd        mov     x29, sp
  400628:       a90153f3        stp     x19, x20, [sp,#16]
  40062c:       a90363f7        stp     x23, x24, [sp,#48]
  400630:       f00000f4        adrp    x20, 41f000 <__FRAME_END__+0x1e7e8>
  400634:       f00000f8        adrp    x24, 41f000 <__FRAME_END__+0x1e7e8>
  400638:       9137c318        add     x24, x24, #0xdf0
  40063c:       9137e294        add     x20, x20, #0xdf8
  400640:       cb180294        sub     x20, x20, x24
  400644:       9343fe94        asr     x20, x20, #3
  400648:       a9025bf5        stp     x21, x22, [sp,#32]
  40064c:       2a0003f7        mov     w23, w0
  400650:       aa0103f6        mov     x22, x1
  400654:       aa0203f5        mov     x21, x2
  400658:       d2800013        mov     x19, #0x0                       // #0
  40065c:       97ffff73        bl      400428 <_init>
  400660:       b4000134        cbz     x20, 400684 <__libc_csu_init+0x64>
  400664:       f8737b03        ldr     x3, [x24,x19,lsl #3]
  400668:       2a1703e0        mov     w0, w23
  40066c:       aa1603e1        mov     x1, x22
  400670:       aa1503e2        mov     x2, x21
  400674:       d63f0060        blr     x3
  400678:       91000673        add     x19, x19, #0x1
  40067c:       eb14027f        cmp     x19, x20
  400680:       54ffff21        b.ne    400664 <__libc_csu_init+0x44>
  400684:       a94153f3        ldp     x19, x20, [sp,#16]
  400688:       a9425bf5        ldp     x21, x22, [sp,#32]
  40068c:       a94363f7        ldp     x23, x24, [sp,#48]
  400690:       a8c47bfd        ldp     x29, x30, [sp],#64
  400694:       d65f03c0        ret

0000000000400698 <__libc_csu_fini>:
  400698:       d65f03c0        ret

Disassembly of section .fini:

000000000040069c <_fini>:
  40069c:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
  4006a0:       910003fd        mov     x29, sp
  4006a4:       a8c17bfd        ldp     x29, x30, [sp],#16
  4006a8:       d65f03c0        ret

asm-example