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From:   Oscar Carter <oscar.carter@gmx.com>
To:     Kees Cook <keescook@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>
Cc:     kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org,
        Oscar Carter <oscar.carter@gmx.com>
Subject: [PATCH] kernel/trace: Remove function callback casts
Date:   Sun, 14 Jun 2020 09:01:54 +0200
Message-Id: <20200614070154.6039-1-oscar.carter@gmx.com>
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Sender: linux-kernel-owner@vger.kernel.org
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In an effort to enable -Wcast-function-type in the top-level Makefile to
support Control Flow Integrity builds, remove all the function callback
casts.

To do this, use the ftrace_ops_list_func function as a wrapper when the
arch not supports ftrace ops instead of the use of a function cast.

Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
=2D--
 kernel/trace/ftrace.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c163c3531faf..ed1efc0e3a25 100644
=2D-- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -119,13 +119,12 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_most=
ly =3D &ftrace_list_end;
 ftrace_func_t ftrace_trace_function __read_mostly =3D ftrace_stub;
 struct ftrace_ops global_ops;

-#if ARCH_SUPPORTS_FTRACE_OPS
 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_i=
p,
 				 struct ftrace_ops *op, struct pt_regs *regs);
-#else
+
+#if !ARCH_SUPPORTS_FTRACE_OPS
 /* See comment below, where ftrace_ops_list_func is defined */
 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
-#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
 #endif

 static inline void ftrace_ops_init(struct ftrace_ops *ops)
@@ -6860,6 +6859,12 @@ static void ftrace_ops_list_func(unsigned long ip, =
unsigned long parent_ip,
 }
 NOKPROBE_SYMBOL(ftrace_ops_list_func);
 #else
+static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_i=
p,
+				 struct ftrace_ops *op, struct pt_regs *regs)
+{
+	ftrace_ops_no_ops(ip, parent_ip);
+}
+
 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
 {
 	__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
=2D-
2.20.1