On Thu, Mar 21, 2019 at 11:18:05AM -0700, h...@zytor.com wrote:
> On March 21, 2019 10:25:05 AM PDT, Denys Vlasenko wrote:
> >I did not see evidence of this. In my testing,
> >POPF is always ~20 cycles, even if popped flags are identical to
> >current state of flags.
>
> I think you will find
On Thu, Mar 21, 2019 at 10:25 AM Denys Vlasenko wrote:
>
> >
> > But iirc pushf/popf isn't really that expensive - in fact I think it's
> > pretty cheap when system flags don't change.
>
> I did not see evidence of this. In my testing,
> POPF is always ~20 cycles, even if popped flags are
On March 21, 2019 10:25:05 AM PDT, Denys Vlasenko wrote:
>On 3/18/19 7:10 PM, Linus Torvalds wrote:
>> On Mon, Mar 18, 2019 at 10:51 AM Peter Zijlstra
> wrote:
>>>
>>> How about I do a patch that schedules EFLAGS for both 32bit and
>64bit,
>>> mark this for backporting to infinity.
>>>
>>> And
On 3/18/19 7:10 PM, Linus Torvalds wrote:
On Mon, Mar 18, 2019 at 10:51 AM Peter Zijlstra wrote:
How about I do a patch that schedules EFLAGS for both 32bit and 64bit,
mark this for backporting to infinity.
And then at the end, after the objtool-ac bits land, I do a patch
removing the EFLAGS
On March 18, 2019 11:10:22 AM PDT, Linus Torvalds
wrote:
>On Mon, Mar 18, 2019 at 10:51 AM Peter Zijlstra
>wrote:
>>
>> How about I do a patch that schedules EFLAGS for both 32bit and
>64bit,
>> mark this for backporting to infinity.
>>
>> And then at the end, after the objtool-ac bits land, I
On Mon, Mar 18, 2019 at 10:51 AM Peter Zijlstra wrote:
>
> How about I do a patch that schedules EFLAGS for both 32bit and 64bit,
> mark this for backporting to infinity.
>
> And then at the end, after the objtool-ac bits land, I do a patch
> removing the EFLAGS scheduling for x86_64.
Sounds
On Mon, Mar 18, 2019 at 06:36:57PM +0100, Peter Zijlstra wrote:
> then I'd sleep much better if we make 32bit context switch EFLAGS.
> Because, yes, x86_64 objtool validates a lot of the x86_32 code too, but
> unless we have 100% coverage, there's always the chance an AC=1 escapes.
How about I do
On Mon, Mar 18, 2019 at 09:58:20AM -0700, Linus Torvalds wrote:
> On Mon, Mar 18, 2019 at 8:54 AM Peter Zijlstra wrote:
> >
> > We rely on objtool to verify AC=1 doesn't escape. However there is no
> > objtool support for x86_32, and thus we cannot guarantee the
> > correctness of the 32bit code.
On Mon, Mar 18, 2019 at 8:54 AM Peter Zijlstra wrote:
>
> We rely on objtool to verify AC=1 doesn't escape. However there is no
> objtool support for x86_32, and thus we cannot guarantee the
> correctness of the 32bit code.
Absolutely not.
This is just crazy. We had working SMAP long before
We rely on objtool to verify AC=1 doesn't escape. However there is no
objtool support for x86_32, and thus we cannot guarantee the
correctness of the 32bit code.
Also; if you're running 32bit kernels on hardware with SMAP (which all
should have LM support afaik) you're doing it wrong anyway.
10 matches
Mail list logo