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Date: Mon, 23 Feb 2015 19:16:08 +0100
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Xenomai] ipipe: issues with ARM exception handling
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: Xenomai <xenomai@xenomai.org>

On 2015-02-23 19:11, Gilles Chanteperdrix wrote:
> On Mon, Feb 23, 2015 at 07:04:25PM +0100, Gilles Chanteperdrix wrote:
>> So, finally, I propose:
> 
> Mmmm. try again.
> 
>>
>> static inline unsigned long ipipe_fault_entry(void)
>> {
>> 	unsigned long flags;
>>
>> 	local_irq_save(flags);      /* Re-enables hw irqs */
> 
> We need the explicit hard_local_irq_enable() here.
> 
>>
>> 	return flags;
>> }
>>
>> static inline void ipipe_fault_exit(unsigned long x)
>> {
>> 	if (irqs_disabled()) {
>> 		__ipipe_restore_root_nosync(x);
>> 		hard_local_irq_disable();
>> 	}
>> }
> 
> We need hard_local_irq_disable() before __ipipe_restore_root_nosync,
> to avoid the preemption of a Linux interrupt where this should not
> be possible.

ipipe_restore_root_nosync?

But we first need to understand the differences to x86 to be sure that
we don't miss something. The remaining differences either have to have
an architecture-specific reason - or one side is still wrong (or
needlessly complex).

Jan

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