powerpc/pseries: Use jump labels for hcall tracepoints

Index: b/arch/powerpc/include/asm/jump_label.h
===================================================================
@@ -10,6 +10,7 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#ifndef __ASSEMBLY__
 #include <linux/types.h>
 
 #include <asm/feature-fixups.h>

@@ -42,4 +43,12 @@ struct jump_entry {
 	jump_label_t key;
 };
 
+#else
+#define ARCH_STATIC_BRANCH(LABEL, KEY)		\
+1098:	nop;					\
+	.pushsection __jump_table, "aw";	\
+	FTR_ENTRY_LONG 1098b, LABEL, KEY;	\
+	.popsection
+#endif
+
 #endif /* _ASM_POWERPC_JUMP_LABEL_H */

Index: b/arch/powerpc/platforms/pseries/lpar.c
===================================================================
@@ -26,6 +26,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/console.h>
 #include <linux/export.h>
+#include <linux/static_key.h>
 #include <asm/processor.h>
 #include <asm/mmu.h>
 #include <asm/page.h>

@@ -649,6 +650,19 @@ EXPORT_SYMBOL(arch_free_page);
 #endif
 
 #ifdef CONFIG_TRACEPOINTS
+#ifdef CONFIG_JUMP_LABEL
+struct static_key hcall_tracepoint_key = STATIC_KEY_INIT;
+
+void hcall_tracepoint_regfunc(void)
+{
+	static_key_slow_inc(&hcall_tracepoint_key);
+}
+
+void hcall_tracepoint_unregfunc(void)
+{
+	static_key_slow_dec(&hcall_tracepoint_key);
+}
+#else
 /*
  * We optimise our hcall path by placing hcall_tracepoint_refcount
  * directly in the TOC so we can check if the hcall tracepoints are

@@ -658,13 +672,6 @@ EXPORT_SYMBOL(arch_free_page);
 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
 extern long hcall_tracepoint_refcount;
 
-/* 
- * Since the tracing code might execute hcalls we need to guard against
- * recursion. One example of this are spinlocks calling H_YIELD on
- * shared processor partitions.
- */
-static DEFINE_PER_CPU(unsigned int, hcall_trace_depth);
-
 void hcall_tracepoint_regfunc(void)
 {
 	hcall_tracepoint_refcount++;

@@ -674,6 +681,15 @@ void hcall_tracepoint_unregfunc(void)
 {
 	hcall_tracepoint_refcount--;
 }
+#endif
+
+/*
+ * Since the tracing code might execute hcalls we need to guard against
+ * recursion. One example of this are spinlocks calling H_YIELD on
+ * shared processor partitions.
+ */
+static DEFINE_PER_CPU(unsigned int, hcall_trace_depth);
+
 
 void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
 {