c程序
// mstore.c
long mult2(long, long);
void multstore(long x, long y, long *dest){
long t = mult2(x, y);
*dest = t;
}使用編譯器編譯成彙編語言
- 編譯命令
gcc -Og -S mstore.c- 內容如下
.file "mstore.c"
.text
.globl multstore
.type multstore, @function
multstore:
.LFB0:
.cfi_startproc
pushq %rbx
.cfi_def_cfa_offset 16
.cfi_offset 3, -16
movq %rdx, %rbx
call mult2
movq %rax, (%rbx)
popq %rbx
.cfi_def_cfa_offset 8
ret
.cfi_endproc
.LFE0:
.size multstore, .-multstore
.ident "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.5) 5.4.0 20160609"
.section .note.GNU-stack,"",@progbits- 包括下面幾行
multstore:
pushq %rbx
movq %rdx, %rbx
call mult2
movq %rax, (%rbx)
popq %rbx
ret- 每一行對應一個機器指令
- 然後編譯成二進制文件
gcc -Og -c mstore.c- 將其反彙編
objdump -d mstore.o二進制代碼與彙編語言
Disassembly of section .text:
0000000000000000 <multstore>:
0: 53 push %rbx
1: 48 89 d3 mov %rdx,%rbx
4: e8 00 00 00 00 callq 9 <multstore+0x9>
9: 48 89 03 mov %rax,(%rbx)
c: 5b pop %rbx
d: c3 retq 另一個c文件 main.c
#include <stdio.h>
void multstore(long, long, long *);
int main(){
long d;
multstore(2,3,&d);
printf("2 * 3 --> %ld\n", d);
return 0;
}
long mult2(long a, long b){
long s = a * b;
return s;
}- 編譯
gcc -Og -o prog main.c mstore.c再一次反彙編
objdump -d prog - 顯示如下
prog： 文件格式 elf64-x86-64
Disassembly of section .init:
0000000000400448 <_init>:
400448: 48 83 ec 08 sub $0x8,%rsp
40044c: 48 8b 05 a5 0b 20 00 mov 0x200ba5(%rip),%rax # 600ff8 <_DYNAMIC+0x1d0>
400453: 48 85 c0 test %rax,%rax
400456: 74 05 je 40045d <_init+0x15>
400458: e8 53 00 00 00 callq 4004b0 <__printf_chk@plt+0x10>
40045d: 48 83 c4 08 add $0x8,%rsp
400461: c3 retq
Disassembly of section .plt:
0000000000400470 <__stack_chk_fail@plt-0x10>:
400470: ff 35 92 0b 20 00 pushq 0x200b92(%rip) # 601008 <_GLOBAL_OFFSET_TABLE_+0x8>
400476: ff 25 94 0b 20 00 jmpq *0x200b94(%rip) # 601010 <_GLOBAL_OFFSET_TABLE_+0x10>
40047c: 0f 1f 40 00 nopl 0x0(%rax)
0000000000400480 <__stack_chk_fail@plt>:
400480: ff 25 92 0b 20 00 jmpq *0x200b92(%rip) # 601018 <_GLOBAL_OFFSET_TABLE_+0x18>
400486: 68 00 00 00 00 pushq $0x0
40048b: e9 e0 ff ff ff jmpq 400470 <_init+0x28>
0000000000400490 <__libc_start_main@plt>:
400490: ff 25 8a 0b 20 00 jmpq *0x200b8a(%rip) # 601020 <_GLOBAL_OFFSET_TABLE_+0x20>
400496: 68 01 00 00 00 pushq $0x1
40049b: e9 d0 ff ff ff jmpq 400470 <_init+0x28>
00000000004004a0 <__printf_chk@plt>:
4004a0: ff 25 82 0b 20 00 jmpq *0x200b82(%rip) # 601028 <_GLOBAL_OFFSET_TABLE_+0x28>
4004a6: 68 02 00 00 00 pushq $0x2
4004ab: e9 c0 ff ff ff jmpq 400470 <_init+0x28>
Disassembly of section .plt.got:
00000000004004b0 <.plt.got>:
4004b0: ff 25 42 0b 20 00 jmpq *0x200b42(%rip) # 600ff8 <_DYNAMIC+0x1d0>
4004b6: 66 90 xchg %ax,%ax
Disassembly of section .text:
00000000004004c0 <_start>:
4004c0: 31 ed xor %ebp,%ebp
4004c2: 49 89 d1 mov %rdx,%r9
4004c5: 5e pop %rsi
4004c6: 48 89 e2 mov %rsp,%rdx
4004c9: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
4004cd: 50 push %rax
4004ce: 54 push %rsp
4004cf: 49 c7 c0 a0 06 40 00 mov $0x4006a0,%r8
4004d6: 48 c7 c1 30 06 40 00 mov $0x400630,%rcx
4004dd: 48 c7 c7 b6 05 40 00 mov $0x4005b6,%rdi
4004e4: e8 a7 ff ff ff callq 400490 <__libc_start_main@plt>
4004e9: f4 hlt
4004ea: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
00000000004004f0 <deregister_tm_clones>:
4004f0: b8 47 10 60 00 mov $0x601047,%eax
4004f5: 55 push %rbp
4004f6: 48 2d 40 10 60 00 sub $0x601040,%rax
4004fc: 48 83 f8 0e cmp $0xe,%rax
400500: 48 89 e5 mov %rsp,%rbp
400503: 76 1b jbe 400520 <deregister_tm_clones+0x30>
400505: b8 00 00 00 00 mov $0x0,%eax
40050a: 48 85 c0 test %rax,%rax
40050d: 74 11 je 400520 <deregister_tm_clones+0x30>
40050f: 5d pop %rbp
400510: bf 40 10 60 00 mov $0x601040,%edi
400515: ff e0 jmpq *%rax
400517: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
40051e: 00 00
400520: 5d pop %rbp
400521: c3 retq
400522: 0f 1f 40 00 nopl 0x0(%rax)
400526: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
40052d: 00 00 00
0000000000400530 <register_tm_clones>:
400530: be 40 10 60 00 mov $0x601040,%esi
400535: 55 push %rbp
400536: 48 81 ee 40 10 60 00 sub $0x601040,%rsi
40053d: 48 c1 fe 03 sar $0x3,%rsi
400541: 48 89 e5 mov %rsp,%rbp
400544: 48 89 f0 mov %rsi,%rax
400547: 48 c1 e8 3f shr $0x3f,%rax
40054b: 48 01 c6 add %rax,%rsi
40054e: 48 d1 fe sar %rsi
400551: 74 15 je 400568 <register_tm_clones+0x38>
400553: b8 00 00 00 00 mov $0x0,%eax
400558: 48 85 c0 test %rax,%rax
40055b: 74 0b je 400568 <register_tm_clones+0x38>
40055d: 5d pop %rbp
40055e: bf 40 10 60 00 mov $0x601040,%edi
400563: ff e0 jmpq *%rax
400565: 0f 1f 00 nopl (%rax)
400568: 5d pop %rbp
400569: c3 retq
40056a: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
0000000000400570 <__do_global_dtors_aux>:
400570: 80 3d c9 0a 20 00 00 cmpb $0x0,0x200ac9(%rip) # 601040 <__TMC_END__>
400577: 75 11 jne 40058a <__do_global_dtors_aux+0x1a>
400579: 55 push %rbp
40057a: 48 89 e5 mov %rsp,%rbp
40057d: e8 6e ff ff ff callq 4004f0 <deregister_tm_clones>
400582: 5d pop %rbp
400583: c6 05 b6 0a 20 00 01 movb $0x1,0x200ab6(%rip) # 601040 <__TMC_END__>
40058a: f3 c3 repz retq
40058c: 0f 1f 40 00 nopl 0x0(%rax)
0000000000400590 <frame_dummy>:
400590: bf 20 0e 60 00 mov $0x600e20,%edi
400595: 48 83 3f 00 cmpq $0x0,(%rdi)
400599: 75 05 jne 4005a0 <frame_dummy+0x10>
40059b: eb 93 jmp 400530 <register_tm_clones>
40059d: 0f 1f 00 nopl (%rax)
4005a0: b8 00 00 00 00 mov $0x0,%eax
4005a5: 48 85 c0 test %rax,%rax
4005a8: 74 f1 je 40059b <frame_dummy+0xb>
4005aa: 55 push %rbp
4005ab: 48 89 e5 mov %rsp,%rbp
4005ae: ff d0 callq *%rax
4005b0: 5d pop %rbp
4005b1: e9 7a ff ff ff jmpq 400530 <register_tm_clones>
00000000004005b6 <main>:
4005b6: 48 83 ec 18 sub $0x18,%rsp
4005ba: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
4005c1: 00 00
4005c3: 48 89 44 24 08 mov %rax,0x8(%rsp)
4005c8: 31 c0 xor %eax,%eax
4005ca: 48 89 e2 mov %rsp,%rdx
4005cd: be 03 00 00 00 mov $0x3,%esi
4005d2: bf 02 00 00 00 mov $0x2,%edi
4005d7: e8 3f 00 00 00 callq 40061b <multstore>
4005dc: 48 8b 14 24 mov (%rsp),%rdx
4005e0: be b4 06 40 00 mov $0x4006b4,%esi
4005e5: bf 01 00 00 00 mov $0x1,%edi
4005ea: b8 00 00 00 00 mov $0x0,%eax
4005ef: e8 ac fe ff ff callq 4004a0 <__printf_chk@plt>
4005f4: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx
4005f9: 64 48 33 0c 25 28 00 xor %fs:0x28,%rcx
400600: 00 00
400602: 74 05 je 400609 <main+0x53>
400604: e8 77 fe ff ff callq 400480 <__stack_chk_fail@plt>
400609: b8 00 00 00 00 mov $0x0,%eax
40060e: 48 83 c4 18 add $0x18,%rsp
400612: c3 retq
0000000000400613 <mult2>:
400613: 48 89 f8 mov %rdi,%rax
400616: 48 0f af c6 imul %rsi,%rax
40061a: c3 retq
000000000040061b <multstore>:
40061b: 53 push %rbx
40061c: 48 89 d3 mov %rdx,%rbx
40061f: e8 ef ff ff ff callq 400613 <mult2>
400624: 48 89 03 mov %rax,(%rbx)
400627: 5b pop %rbx
400628: c3 retq
400629: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0000000000400630 <__libc_csu_init>:
400630: 41 57 push %r15
400632: 41 56 push %r14
400634: 41 89 ff mov %edi,%r15d
400637: 41 55 push %r13
400639: 41 54 push %r12
40063b: 4c 8d 25 ce 07 20 00 lea 0x2007ce(%rip),%r12 # 600e10 <__frame_dummy_init_array_entry>
400642: 55 push %rbp
400643: 48 8d 2d ce 07 20 00 lea 0x2007ce(%rip),%rbp # 600e18 <__init_array_end>
40064a: 53 push %rbx
40064b: 49 89 f6 mov %rsi,%r14
40064e: 49 89 d5 mov %rdx,%r13
400651: 4c 29 e5 sub %r12,%rbp
400654: 48 83 ec 08 sub $0x8,%rsp
400658: 48 c1 fd 03 sar $0x3,%rbp
40065c: e8 e7 fd ff ff callq 400448 <_init>
400661: 48 85 ed test %rbp,%rbp
400664: 74 20 je 400686 <__libc_csu_init+0x56>
400666: 31 db xor %ebx,%ebx
400668: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
40066f: 00
400670: 4c 89 ea mov %r13,%rdx
400673: 4c 89 f6 mov %r14,%rsi
400676: 44 89 ff mov %r15d,%edi
400679: 41 ff 14 dc callq *(%r12,%rbx,8)
40067d: 48 83 c3 01 add $0x1,%rbx
400681: 48 39 eb cmp %rbp,%rbx
400684: 75 ea jne 400670 <__libc_csu_init+0x40>
400686: 48 83 c4 08 add $0x8,%rsp
40068a: 5b pop %rbx
40068b: 5d pop %rbp
40068c: 41 5c pop %r12
40068e: 41 5d pop %r13
400690: 41 5e pop %r14
400692: 41 5f pop %r15
400694: c3 retq
400695: 90 nop
400696: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
40069d: 00 00 00
00000000004006a0 <__libc_csu_fini>:
4006a0: f3 c3 repz retq
Disassembly of section .fini:
00000000004006a4 <_fini>:
4006a4: 48 83 ec 08 sub $0x8,%rsp
4006a8: 48 83 c4 08 add $0x8,%rsp
4006ac: c3 retq - 有如下一段
000000000040061b <multstore>:
40061b: 53 push %rbx
40061c: 48 89 d3 mov %rdx,%rbx
40061f: e8 ef ff ff ff callq 400613 <mult2>
400624: 48 89 03 mov %rax,(%rbx)
400627: 5b pop %rbx
400628: c3 retq
400629: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)這段代碼與
mstore.c反彙編產生的代碼幾乎一模一樣，但又三個區別。- 左邊的地址不同——鏈接器將這段代碼移動到一段不同的地址範圍中，
- 鏈接器填上了
callq指令調用函數mult2需要使用的地址。鏈接器的任務之一就是爲函數調用找到匹配的函數的可執行的代碼的位置。 - 最後多了兩行代碼。對於程序沒影響，這是爲了函數代碼變爲16字節，使得就存儲器系統性能而言，更好地放置下一個代碼塊。
其中，以
.開頭的命令都是指導彙編器與鏈接器工作的僞指令。