On Fri, Apr 06, 2018 at 06:22:11PM +0100, Mark Rutland wrote:
> Digging a bit, I also thing that our ct_user_exit and ct_user_enter
> usage is on dodgy ground today.
>
> For example, in el0_dbg we call do_debug_exception() *before* calling
> ct_user_exit. Which I believe means we'd use RCU while s
On Fri, Apr 06, 2018 at 06:30:50PM +0100, James Morse wrote:
> Hi Mark,
>
> On 06/04/18 18:22, Mark Rutland wrote:
> > Digging a bit, I also thing that our ct_user_exit and ct_user_enter
> > usage is on dodgy ground today.
>
> [...]
>
> > I think similar applies to SDEI; we don't negotiate with
Hi Mark,
On 06/04/18 18:22, Mark Rutland wrote:
> Digging a bit, I also thing that our ct_user_exit and ct_user_enter
> usage is on dodgy ground today.
[...]
> I think similar applies to SDEI; we don't negotiate with RCU prior to
> invoking handlers, which might need RCU.
The arch code's __sdei
On Fri, Apr 06, 2018 at 07:54:02PM +0300, Yury Norov wrote:
> In general, kick_all_cpus_sync() is needed to switch contexts. But exit from
> userspace is anyway the switch of context. And while in userspace, we cannot
> do something wrong on kernel side. For me it means that we can safely drop
> IP
On Fri, Apr 06, 2018 at 11:02:56AM +0100, James Morse wrote:
> Hi Yury,
>
> An ISB at the beginning of the vectors? This is odd, taking an IRQ to get in
> here would be a context-synchronization-event too, so the ISB is superfluous.
>
> The ARM-ARM has a list of 'Context-Synchronization event's
On Thu, Apr 05, 2018 at 08:17:56PM +0300, Yury Norov wrote:
> Kernel text patching framework relies on IPI to ensure that other
> SMP cores observe the change. Target core calls isb() in IPI handler
> path, but not at the beginning of el1_irq entry. There's a chance
> that modified instruction will
Hi Yury,
On 05/04/18 18:17, Yury Norov wrote:
> Kernel text patching framework relies on IPI to ensure that other
> SMP cores observe the change. Target core calls isb() in IPI handler
(Odd, if its just to synchronize the CPU, taking the IPI should be enough).
> path, but not at the beginning o
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