powerpc: Rework runlatch code

This moves the inlines into system.h and changes the runlatch
code to use the thread local flags (non-atomic) rather than
the TIF flags (atomic) to keep track of the latch state.

The code to turn it back on in an asynchronous interrupt is
now simplified and partially inlined.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index d817ab0..bf80a1d 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1220,34 +1220,32 @@
 EXPORT_SYMBOL(dump_stack);
 
 #ifdef CONFIG_PPC64
-void ppc64_runlatch_on(void)
+/* Called with hard IRQs off */
+void __ppc64_runlatch_on(void)
 {
+	struct thread_info *ti = current_thread_info();
 	unsigned long ctrl;
 
-	if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
-		HMT_medium();
+	ctrl = mfspr(SPRN_CTRLF);
+	ctrl |= CTRL_RUNLATCH;
+	mtspr(SPRN_CTRLT, ctrl);
 
-		ctrl = mfspr(SPRN_CTRLF);
-		ctrl |= CTRL_RUNLATCH;
-		mtspr(SPRN_CTRLT, ctrl);
-
-		set_thread_flag(TIF_RUNLATCH);
-	}
+	ti->local_flags |= TLF_RUNLATCH;
 }
 
+/* Called with hard IRQs off */
 void __ppc64_runlatch_off(void)
 {
+	struct thread_info *ti = current_thread_info();
 	unsigned long ctrl;
 
-	HMT_medium();
-
-	clear_thread_flag(TIF_RUNLATCH);
+	ti->local_flags &= ~TLF_RUNLATCH;
 
 	ctrl = mfspr(SPRN_CTRLF);
 	ctrl &= ~CTRL_RUNLATCH;
 	mtspr(SPRN_CTRLT, ctrl);
 }
-#endif
+#endif /* CONFIG_PPC64 */
 
 #if THREAD_SHIFT < PAGE_SHIFT