1 files changed, 84 insertions, 0 deletions
diff --git a/kernel/arch/powerpc/platforms/powernv/opal-tracepoints.c b/kernel/arch/powerpc/platforms/powernv/opal-tracepoints.c
new file mode 100644
index 000000000..e11273b23
--- /dev/null
+++ b/kernel/arch/powerpc/platforms/powernv/opal-tracepoints.c
@@ -0,0 +1,84 @@
+#include <linux/percpu.h>
+#include <linux/jump_label.h>
+#include <asm/trace.h>
+
+#ifdef HAVE_JUMP_LABEL
+struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
+
+void opal_tracepoint_regfunc(void)
+{
+	static_key_slow_inc(&opal_tracepoint_key);
+}
+
+void opal_tracepoint_unregfunc(void)
+{
+	static_key_slow_dec(&opal_tracepoint_key);
+}
+#else
+/*
+ * We optimise OPAL calls by placing opal_tracepoint_refcount
+ * directly in the TOC so we can check if the opal tracepoints are
+ * enabled via a single load.
+ */
+
+/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
+extern long opal_tracepoint_refcount;
+
+void opal_tracepoint_regfunc(void)
+{
+	opal_tracepoint_refcount++;
+}
+
+void opal_tracepoint_unregfunc(void)
+{
+	opal_tracepoint_refcount--;
+}
+#endif
+
+/*
+ * Since the tracing code might execute OPAL calls we need to guard against
+ * recursion.
+ */
+static DEFINE_PER_CPU(unsigned int, opal_trace_depth);
+
+void __trace_opal_entry(unsigned long opcode, unsigned long *args)
+{
+	unsigned long flags;
+	unsigned int *depth;
+
+	local_irq_save(flags);
+
+	depth = this_cpu_ptr(&opal_trace_depth);
+
+	if (*depth)
+		goto out;
+
+	(*depth)++;
+	preempt_disable();
+	trace_opal_entry(opcode, args);
+	(*depth)--;
+
+out:
+	local_irq_restore(flags);
+}
+
+void __trace_opal_exit(long opcode, unsigned long retval)
+{
+	unsigned long flags;
+	unsigned int *depth;
+
+	local_irq_save(flags);
+
+	depth = this_cpu_ptr(&opal_trace_depth);
+
+	if (*depth)
+		goto out;
+
+	(*depth)++;
+	trace_opal_exit(opcode, retval);
+	preempt_enable();
+	(*depth)--;
+
+out:
+	local_irq_restore(flags);
+}