GAS: jmp to label results in wrong jump?
I am trying to assembly following program:
.text
.globl _search2
_se开发者_JAVA百科arch2:
pushq %rbp
movq %rsp, %rbp
movq %rax, -8(%rbp)
go_again:
cmpl $0x90909090, (%rax)
je go_out
addq $0x8, %rax
jmp go_again
go_out:
leave
ret
by doing this: "gcc -o test test.s main.c" and I get this:
otool -v -t test
_search2:
0000000100000d0c pushq %rbp
0000000100000d0d movq %rsp,%rbp
0000000100000d10 movq %rax,0xf8(%rbp)
go_again:
0000000100000d14 cmpl $0x90909090,(%rax)
0000000100000d1a je 0x100000d29
0000000100000d20 addq $0x08,%rax
0000000100000d24 jmp 0x200000d14
go_out:
0000000100000d29 leave
0000000100000d2a ret
The jmp is trying to jump to address 0x200000d14 which is totally wrong instead of 0x100000d29 which is marked with go_out label.
Please help.
Try objdump -D test > test.list
00000000004004c4 <_search2>:
4004c4: 55 push %rbp
4004c5: 48 89 e5 mov %rsp,%rbp
4004c8: 48 89 45 f8 mov %rax,-0x8(%rbp)
00000000004004cc <go_again>:
4004cc: 81 38 90 90 90 90 cmpl $0x90909090,(%rax)
4004d2: 74 06 je 4004da <go_out>
4004d4: 48 83 c0 08 add $0x8,%rax
4004d8: eb f2 jmp 4004cc <go_again>
00000000004004da <go_out>:
4004da: c9 leaveq
4004db: c3 retq
See if the tool you are using can display the instructions, if the instructions are the (somewhat the) same then the relative address is correct and you can ignore the address the tool is displaying, or just not use that tool.
If the branches are direct and dont match the target, then there is a gcc/gnu tools problem.
精彩评论