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Re: [PATCH 3/4] x86/intel lbr: down with test_thread_flag(TIF_IA32)

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  Re: [PATCH 3/4] x86/intel lbr: down with test_thread_flag(TIF_IA32) Peter Zijlstra <peterz@infradead.org> - 2016-04-20 13:30 +0200
    Re: [PATCH 3/4] x86/intel lbr: down with test_thread_flag(TIF_IA32) Dmitry Safonov <dsafonov@virtuozzo.com> - 2016-04-20 16:00 +0200

#1383313 — Re: [PATCH 3/4] x86/intel lbr: down with test_thread_flag(TIF_IA32)

On Thu, Apr 14, 2016 at 12:29:12PM -0700, Andy Lutomirski wrote:
> On Thu, Apr 14, 2016 at 11:10 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:

> > @@ -724,7 +727,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
> >          * on 64-bit systems running 32-bit apps
> >          */
> >  #ifdef CONFIG_X86_64
> > -       is64 = kernel_ip((unsigned long)addr) || !test_thread_flag(TIF_IA32);
> > +       is64 = kernel_ip((unsigned long)addr) || user_64bit_mode(regs);
> 
> Peterz, looking at this some more, would it make sense to pass
> user_regs and interrupt_regs (or whatever we'd call it) all the way
> through to here?

Urgh; again, wtf wasn't I Cc'ed to these patches?

And not sure; if we never need the user regs, calling
perf_get_user_regs() to set all that up seems like a massive waste of
cycles.

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#1383417

On 04/20/2016 02:21 PM, Peter Zijlstra wrote:
> On Thu, Apr 14, 2016 at 12:29:12PM -0700, Andy Lutomirski wrote:
>> On Thu, Apr 14, 2016 at 11:10 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:
>>> @@ -724,7 +727,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
>>>           * on 64-bit systems running 32-bit apps
>>>           */
>>>   #ifdef CONFIG_X86_64
>>> -       is64 = kernel_ip((unsigned long)addr) || !test_thread_flag(TIF_IA32);
>>> +       is64 = kernel_ip((unsigned long)addr) || user_64bit_mode(regs);
>> Peterz, looking at this some more, would it make sense to pass
>> user_regs and interrupt_regs (or whatever we'd call it) all the way
>> through to here?
> Urgh; again, wtf wasn't I Cc'ed to these patches?

Sorry for that - that was my unintentional miss on git-send-email.

> And not sure; if we never need the user regs, calling
> perf_get_user_regs() to set all that up seems like a massive waste of
> cycles.

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