[RFC PATCH 05/16] rv/include: Add tracing helper functions

[Daniel Bristot de Oliveira <bristot@redhat.com>]

Tracing helper functions to facilitate the instrumentation of
auto-generated RV monitors create by dot2k.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Paoloni <gabriele.paoloni@intel.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
---
 include/rv/trace_helpers.h | 69 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 include/rv/trace_helpers.h

diff --git a/include/rv/trace_helpers.h b/include/rv/trace_helpers.h
new file mode 100644
index 000000000000..1a8b6f246d0d
--- /dev/null
+++ b/include/rv/trace_helpers.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Helper functions to facilitate the instrumentation of auto-generated
+ * RV monitors create by dot2k.
+ *
+ * The dot2k tool is available at tools/tracing/rv/dot2/
+ *
+ * Copyright (C) 2019-2021 Daniel Bristot de Oliveira <bristot@redhat.com>
+ */
+
+#include <linux/ftrace.h>
+
+struct tracepoint_hook_helper {
+	struct tracepoint *tp;
+	void *probe;
+	int registered;
+	char *name;
+};
+
+static inline void thh_compare_name(struct tracepoint *tp, void *priv)
+{
+	struct tracepoint_hook_helper *thh  = priv;
+
+	if (!strcmp(thh->name, tp->name))
+		thh->tp = tp;
+}
+
+static inline bool thh_fill_struct_tracepoint(struct tracepoint_hook_helper *thh)
+{
+	for_each_kernel_tracepoint(thh_compare_name, thh);
+
+	return !!thh->tp;
+}
+
+static inline void thh_unhook_probes(struct tracepoint_hook_helper *thh, int helpers_count)
+{
+	int i;
+
+	for (i = 0; i < helpers_count; i++) {
+		if (!thh[i].registered)
+			continue;
+
+		tracepoint_probe_unregister(thh[i].tp, thh[i].probe, NULL);
+	}
+}
+
+static inline int thh_hook_probes(struct tracepoint_hook_helper *thh, int helpers_count)
+{
+	int retval;
+	int i;
+
+	for (i = 0; i < helpers_count; i++) {
+		retval = thh_fill_struct_tracepoint(&thh[i]);
+		if (!retval)
+			goto out_err;
+
+		retval = tracepoint_probe_register(thh[i].tp, thh[i].probe, NULL);
+
+		if (retval)
+			goto out_err;
+
+		thh[i].registered = 1;
+	}
+	return 0;
+
+out_err:
+	thh_unhook_probes(thh, helpers_count);
+	return -EINVAL;
+}
-- 
2.26.2