-
Notifications
You must be signed in to change notification settings - Fork 1.5k
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
bnd jne instruction #955
Comments
Is this from master, or next branch?
Can you provide the input of this case?
|
@aquynh the result disassembled by IDA |
ok, but you havent provided the input code yet: what you gave is only assembly & instruction address. you can enable Opcode output from menu "Options" -> "General ..." -> "Number of opcode bytes" . You can put 8 in this box, press OK, then paste the output here again. |
@aquynh |
all jump instructions should not associate with REP prefix, so IDA is confused here. ping @radare. |
i should check the intel manual to confirm that behaviour, but it will be good to compare with other disassemblers too.
… On 6 Jul 2017, at 07:19, Nguyen Anh Quynh ***@***.***> wrote:
all jump instructions should not associate with REP prefix, so IDA is confused here.
ping @radare <https://github.com/radare>.
—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub <#955 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AA3-lhlXXympcb8uH4H_GLOw22nEEVuvks5sLG5mgaJpZM4OPEB3>.
|
according to Intel manual, REP prefix is only relevant for string instructions + IN/OUT. it is wrong to have REP with jump instructions. |
Some old AMD CPUs exhibit a branch prediction bug when you have a jump going straight to another jump (or return). Jumping to the rep prefix instead is a workaround for it. Both Intel and AMD CPUs tolerate it without any adverse effects. |
yes, but i mean it is better to remove REP in the disassembly output in such a case. |
I use IDA and capstone to disassemble a PE file. But there's a difference, which is bnd jne in capstone but repne jnz short in IDA. Would you please tell the reason?
The text was updated successfully, but these errors were encountered: