On Fri, 2010-07-09 at 16:16 +1000, Benjamin Herrenschmidt wrote: > We use a similar technique to ppc32: We set a thread local flag > to indicate that we are about to enter or have entered the stop > state, and have fixup code in the async interrupt entry code that > reacts to this flag to make us return to a different location > (sets NIP to LINK in our case).
.../... Commenting on my own patch ... :-) This has issues: > +_GLOBAL(book3e_idle) > + /* Save LR for later */ > + mflr r0 > + std r0,16(r1) > + > + /* Hard disable interrupts */ > + wrteei 0 > + > + /* Now check if an interrupt came in while we were soft disabled > + * since we may otherwise lose it (doorbells etc...). We know > + * that since PACAHARDIRQEN will have been cleared in that case. > + */ > + lbz r3,PACAHARDIRQEN(r13) > + cmpwi cr0,r3,0 > + beqlr > + > + /* Now we are going to mark ourselves as soft and hard enables in > + * order to be able to take interrupts while asleep. We inform lockdep > + * of that. We don't actually turn interrupts on just yet tho. > + */ > +#ifdef CONFIG_TRACE_IRQFLAGS > + bl .trace_hardirqs_on Oops... we just clobbered our saved LR on the stack. Need a stackframe > +#endif > + li r0,1 > + stb r0,PACASOFTIRQEN(r13) > + stb r0,PACAHARDIRQEN(r13) > + > + /* Interrupts will make use return to LR, so get something we want > + * in there > + */ > + bl 1f We return here with IRQs enabled, we really need to turn them back off or bad things will happen if an interrupt pops before we clear TFL_NAPPING. I'll send a respin. Cheers, Ben. > + /* We are back from the interrupt, the caller will local_irq_enable() > + * so to avoid stupid warning, let's turn them off here if irqtrace > + * is enabled. > + */ > +#ifdef CONFIG_TRACE_IRQFLAGS > + li r0,0 > + stb r0,PACASOFTIRQEN(r13) > + bl .trace_hardirqs_off > +#endif > + ld r0,16(r1) > + mtlr r0 > + blr > + > +1: /* Let's set the _TLF_NAPPING flag so interrupts make us return > + * to the right spot > + */ > + clrrdi r11,r1,THREAD_SHIFT > + ld r10,TI_LOCAL_FLAGS(r11) > + ori r10,r10,_TLF_NAPPING > + std r10,TI_LOCAL_FLAGS(r11) > + > + /* We can now re-enable hard interrupts and go to sleep */ > + wrteei 1 > +1: PPC_WAIT(0) > + b 1b > + > +#endif /* CONFIG_PPC64 */ > \ No newline at end of file _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
