On Fri, Sep 23, 2011 at 05:51:19PM +0100, Marc Zyngier wrote:

+		if (irqnr < 16) {
+			writel_relaxed(irqstat, gic_cpu_base_addr + GIC_CPU_EOI);
+#ifdef CONFIG_SMP
+			do_IPI(irqnr, regs);
+#endif

This doesn't work.  do_IPI is marked as an entry function, and so expects
to be called with the precondition that the pt_regs are stored immediately
above its stack frame, without another function's stack frame in the way.