This header define a bunch of helpers that allow avoiding the
retpoline overhead when calling builtin functions via function pointers.
It boils down to explicitly comparing the function pointers to
known builtin functions and eventually invoke directly the latter.

The macro defined here implement the boilerplate for the above schema
and will be used by the next patches.

Suggested-by: Eric Dumazet <Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 include/linux/indirect_call_wrapper.h | 77 +++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 include/linux/indirect_call_wrapper.h

diff --git a/include/linux/indirect_call_wrapper.h b/include/linux/indirect_call_wrapper.h
new file mode 100644
index 000000000000..57e82b4a166d
--- /dev/null
+++ b/include/linux/indirect_call_wrapper.h

@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_INDIRECT_CALL_WRAPPER_H
+#define _LINUX_INDIRECT_CALL_WRAPPER_H
+
+#ifdef CONFIG_RETPOLINE
+
+/*
+ * INDIRECT_CALL_$NR - wrapper for indirect calls with $NR known builtin
+ *  @f: function pointer
+ *  @name: base name for builtin functions, see INDIRECT_CALLABLE_DECLARE_$NR
+ *  @__VA_ARGS__: arguments for @f
+ *
+ * Avoid retpoline overhead for known builtin, checking @f vs each of them and
+ * eventually invoking directly the builtin function. Fallback to the indirect
+ * call
+ */
+#define INDIRECT_CALL_1(f, name, ...)					\
+	({								\
+		f == name ## 1 ? name ## 1(__VA_ARGS__) :		\