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, 49 insertions, 0 deletions

diff --git a/tools/perf/util/demangle-cxx.cpp b/tools/perf/util/demangle-cxx.cpp
new file mode 100644
index 000000000..85b706641
--- /dev/null
+++ b/tools/perf/util/demangle-cxx.cpp
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "demangle-cxx.h"
+#include <stdlib.h>
+#include <string.h>
+#include <linux/compiler.h>
+
+#ifdef HAVE_LIBBFD_SUPPORT
+#define PACKAGE 'perf'
+#include <bfd.h>
+#endif
+
+#ifdef HAVE_CXA_DEMANGLE_SUPPORT
+#include <cxxabi.h>
+#endif
+
+#if defined(HAVE_LIBBFD_SUPPORT) || defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
+#ifndef DMGL_PARAMS
+#define DMGL_PARAMS     (1 << 0)  /* Include function args */
+#define DMGL_ANSI       (1 << 1)  /* Include const, volatile, etc */
+#endif
+#endif
+
+/*
+ * Demangle C++ function signature
+ *
+ * Note: caller is responsible for freeing demangled string
+ */
+extern "C"
+char *cxx_demangle_sym(const char *str, bool params __maybe_unused,
+                       bool modifiers __maybe_unused)
+{
+#ifdef HAVE_LIBBFD_SUPPORT
+        int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
+
+        return bfd_demangle(NULL, str, flags);
+#elif defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
+        int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
+
+        return cplus_demangle(str, flags);
+#elif defined(HAVE_CXA_DEMANGLE_SUPPORT)
+        char *output;
+        int status;
+
+        output = abi::__cxa_demangle(str, /*output_buffer=*/NULL, /*length=*/NULL, &status);
+        return output;
+#else
+        return NULL;
+#endif
+}