Re: [PATCH v5 07/12] x86: remove the syscall_64 fast-path

[Andy Lutomirski]

> On Jan 28, 2018, at 1:29 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> 
> 
> * Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> 
>> Quoting Linus:
>> 
>>  "Honestly, I'd rather get rid of the fast-path entirely. Compared to
>>   all the PTI mess, it's not even noticeable.
>> 
>>   And if we ever get CPU's that have this all fixed, we can re-visit
>>   introducing the fastpath. But this is all very messy and it doesn't
>>   seem worth it right now.
>> 
>>   If we get rid of the fastpath, we can lay out the slow path slightly
>>   better, and get rid of some of those jump-overs. And we'd get rid of
>>   the ptregs hooks entirely.
>> 
>>   So we can try to make the "slow" path better while at it, but I
>>   really don't think it matters much now in the post-PTI era. Sadly."
> 
> Please fix the title to have the proper prefix and to reference the function that 
> is actually modified by the patch, i.e. something like:
> 
> s/ x86: remove the syscall_64 fast-path
> / x86/entry/64: Remove the entry_SYSCALL_64() fast-path
> 
> With the title fixed:
> 
> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>

I have a very similar but not quite identical version I'll send out shortly.  The difference is that I fixed the silly prologue.

> 
> Thanks,
> 
>    Ingo