powerpc: Remaining 64-bit Book3E support

This contains all the bits that didn't fit in previous patches :-) This
includes the actual exception handlers assembly, the changes to the
kernel entry, other misc bits and wiring it all up in Kconfig.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 65aced7..87df517 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -454,6 +454,24 @@
 #define irqstack_early_init()
 #endif
 
+#ifdef CONFIG_PPC_BOOK3E
+static void __init exc_lvl_early_init(void)
+{
+	unsigned int i;
+
+	for_each_possible_cpu(i) {
+		critirq_ctx[i] = (struct thread_info *)
+			__va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+		dbgirq_ctx[i] = (struct thread_info *)
+			__va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+		mcheckirq_ctx[i] = (struct thread_info *)
+			__va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+	}
+}
+#else
+#define exc_lvl_early_init()
+#endif
+
 /*
  * Stack space used when we detect a bad kernel stack pointer, and
  * early in SMP boots before relocation is enabled.
@@ -513,6 +531,7 @@
 	init_mm.brk = klimit;
 	
 	irqstack_early_init();
+	exc_lvl_early_init();
 	emergency_stack_init();
 
 #ifdef CONFIG_PPC_STD_MMU_64