ARM: 9480/1: entry: expand comment in __switch_tografted

As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 36 insertions, 0 deletions

diff --git a/tools/perf/util/cacheline.h b/tools/perf/util/cacheline.h
new file mode 100644
index 000000000..fe6d5b60a
--- /dev/null
+++ b/tools/perf/util/cacheline.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef PERF_CACHELINE_H
+#define PERF_CACHELINE_H
+
+#include <linux/compiler.h>
+
+int __pure cacheline_size(void);
+
+
+/*
+ * Some architectures have 'Adjacent Cacheline Prefetch' feature,
+ * which performs like the cacheline size being doubled.
+ */
+static inline u64 cl_address(u64 address, bool double_cl)
+{
+	u64 size = cacheline_size();
+
+	if (double_cl)
+		size *= 2;
+
+	/* return the cacheline of the address */
+	return (address & ~(size - 1));
+}
+
+static inline u64 cl_offset(u64 address, bool double_cl)
+{
+	u64 size = cacheline_size();
+
+	if (double_cl)
+		size *= 2;
+
+	/* return the offset inside cacheline */
+	return (address & (size - 1));
+}
+
+#endif // PERF_CACHELINE_H