Re: [PATCH v1 06/27] x86/entry/64: Adapt assembly for PIE support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




> On Oct 20, 2017, at 5:20 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> 
> 
> * Thomas Garnier <thgarnie@xxxxxxxxxx> wrote:
> 
>>>>       */
>>>> -     cmpq    $.Lentry_SYSCALL_64_after_fastpath_call, (%rsp)
>>>> +     leaq    .Lentry_SYSCALL_64_after_fastpath_call(%rip), %r11
>>>> +     cmpq    %r11, (%rsp)
>>>>      jne     1f
> 
>>> This patch seems to add extra overhead to the syscall fast-path even when PIE is
>>> disabled, right?
>> 
>> It does add extra instructions when one is not possible, I preferred
>> that over ifdefing but I can change it.
> 
> So my problem is, this pattern repeats in many other places as well, but sprinking 
> various pieces of assembly code with #ifdefs would be very bad as well.
> 
> I have no good idea how to solve this.
> 
> Thanks,

Ugh, brain was off.  This is a bit messy. We could use a macro for this, too, I suppose.

> 
>    Ingo
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization



[Index of Archives]     [KVM Development]     [Libvirt Development]     [Libvirt Users]     [CentOS Virtualization]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]

  Powered by Linux