Re: [RFC PATCH for 4.18 3/5] rseq: uapi: declare rseq_cs field as union, update includes

[Mathieu Desnoyers]

----- On Jul 6, 2018, at 3:35 PM, Mathieu Desnoyers mathieu.desnoyers@xxxxxxxxxxxx wrote:

> ----- On Jul 6, 2018, at 3:31 PM, Linus Torvalds torvalds@xxxxxxxxxxxxxxxxxxxx
> wrote:
> 
>> On Fri, Jul 6, 2018 at 12:23 PM Mathieu Desnoyers
>> <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>>>
>>> For -rc, I would favor the following simpler approach. Or I could even
>>> just use get_user() instead. Thoughts ?
>> 
>> Please just use "get_user()".
>> 
>> In fact, we should be thinking seriosly about just removing
>> __get_user() entirely. It's wrong. It optimizes the wrong thing
>> entirely. It _used_ to be that the range check was noticeable, and it
>> really isn't any more. These days the expensive parts are the SMAP
>> costs, and both get_user() and __get_user() have those, except
>> get_user() is safer and doesn't waste I$ on inlining the code to
>> disable and re-enable SMAP.
> 
> Will do, thanks!

Should I change all 4 bytes __get_user()/__put_user() in kernel/rseq.c
for get_user()/put_user() to ensure consistency ?

Thanks,

Mathieu

> 
> Mathieu
> 
> 
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com