Re: [PATCH] x86_64,entry: Fix RCX for traced syscalls

From: Andy Lutomirski
Date: Thu Jun 26 2014 - 15:59:27 EST


On Thu, Jun 26, 2014 at 12:56 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>> show RCX == RIP even under strace.
>
> If you think it's really worth the extra instruction?

Hard to say. That extra instruction only happens on slow paths, so I
suspect the slowdown is negligible. On the other hand, having syscall
show a blatant difference in behavior between traced and untraced
processes seems unfortunate.

>
> It's not wrong, but it's not clear if it's useful.

--Andy
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