ircd::prof::arm: Port rdtsc for aarch64. #132

include/ircd/prof/arm.h

@@ -0,0 +1,43 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_PROF_ARM_H
+
+/// ARM platform related
+namespace ircd::prof::arm
+{
+	unsigned long long read_virtual_counter() noexcept;
+}
+
+#if defined(__aarch64__)
+extern inline unsigned long long
+__attribute__((always_inline, gnu_inline, artificial))
+ircd::prof::arm::read_virtual_counter()
+noexcept
+{
+	unsigned long long ret;
+	asm volatile
+	(
+		"mrs %0, cntvct_el0"
+		: "=r" (ret)
+	);
+
+	return ret;
+}
+#else
+extern inline unsigned long long
+__attribute__((always_inline, gnu_inline, artificial))
+ircd::prof::arm::read_virtual_counter()
+noexcept
+{
+	return 0;
+}
+#endif

include/ircd/prof/cycles.h

@@ -21,20 +21,18 @@ namespace ircd
 	using prof::cycles;
 }
 
-#if defined(__x86_64__) || defined(__i386__)
 /// Monotonic reference cycles (since system boot)
 extern inline uint64_t
 __attribute__((flatten, always_inline, gnu_inline, artificial))
 ircd::prof::cycles()
 noexcept
 {
-	return x86::rdtsc();
+	#if defined(__x86_64__) || defined(__i386__)
+		return x86::rdtsc();
+	#elif defined(__aarch64__)
+		return arm::read_virtual_counter();
+	#else
+		static_assert(false, "Select reference cycle counter for platform.");
+		return 0;
+	#endif
 }
-#else
-ircd::prof::cycles()
-noexcept
-{
-	static_assert(false, "Select reference cycle counter for platform.");
-	return 0;
-}
-#endif

include/ircd/prof/prof.h

@@ -34,6 +34,7 @@ namespace ircd::prof
 }
 
 #include "x86.h"
+#include "arm.h"
 #include "vg.h"
 #include "type.h"
 #include "cycles.h"