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Diffstat (limited to 'arch/powerpc/platforms/powernv/opal-tracepoints.c')
-rw-r--r--arch/powerpc/platforms/powernv/opal-tracepoints.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-tracepoints.c b/arch/powerpc/platforms/powernv/opal-tracepoints.c
new file mode 100644
index 000000000..91b36541b
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-tracepoints.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/percpu.h>
+#include <linux/jump_label.h>
+#include <asm/trace.h>
+
+#ifdef CONFIG_JUMP_LABEL
+struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
+
+int opal_tracepoint_regfunc(void)
+{
+ static_key_slow_inc(&opal_tracepoint_key);
+ return 0;
+}
+
+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;
+
+int opal_tracepoint_regfunc(void)
+{
+ opal_tracepoint_refcount++;
+ return 0;
+}
+
+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);
+}