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, 90 insertions, 0 deletions

diff --git a/tools/perf/ui/util.c b/tools/perf/ui/util.c
new file mode 100644
index 000000000..1d38ddf01
--- /dev/null
+++ b/tools/perf/ui/util.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "util.h"
+#include "../util/debug.h"
+#include <stdio.h>
+
+/*
+ * Default error logging functions
+ */
+static int perf_stdio__error(const char *format, va_list args)
+{
+	fprintf(stderr, "Error:\n");
+	vfprintf(stderr, format, args);
+	return 0;
+}
+
+static int perf_stdio__warning(const char *format, va_list args)
+{
+	if (quiet)
+		return 0;
+
+	fprintf(stderr, "Warning:\n");
+	vfprintf(stderr, format, args);
+	return 0;
+}
+
+static struct perf_error_ops default_eops =
+{
+	.error		= perf_stdio__error,
+	.warning	= perf_stdio__warning,
+};
+
+static struct perf_error_ops *perf_eops = &default_eops;
+
+
+int ui__error(const char *format, ...)
+{
+	int ret;
+	va_list args;
+
+	va_start(args, format);
+	ret = perf_eops->error(format, args);
+	va_end(args);
+
+	return ret;
+}
+
+int ui__warning(const char *format, ...)
+{
+	int ret;
+	va_list args;
+	if (quiet)
+		return 0;
+
+	va_start(args, format);
+	ret = perf_eops->warning(format, args);
+	va_end(args);
+
+	return ret;
+}
+
+/**
+ * perf_error__register - Register error logging functions
+ * @eops: The pointer to error logging function struct
+ *
+ * Register UI-specific error logging functions. Before calling this,
+ * other logging functions should be unregistered, if any.
+ */
+int perf_error__register(struct perf_error_ops *eops)
+{
+	if (perf_eops != &default_eops)
+		return -1;
+
+	perf_eops = eops;
+	return 0;
+}
+
+/**
+ * perf_error__unregister - Unregister error logging functions
+ * @eops: The pointer to error logging function struct
+ *
+ * Unregister already registered error logging functions.
+ */
+int perf_error__unregister(struct perf_error_ops *eops)
+{
+	if (perf_eops != eops)
+		return -1;
+
+	perf_eops = &default_eops;
+	return 0;
+}