linux-kernel - [PATCH 1/1] fentry: x86, cleanup function

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Date:   Wed, 15 Mar 2017 14:44:36 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     mingo@...hat.com
Cc:     linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 1/1] fentry: x86, cleanup function_hook uses

Let's define fentry_hook depending on CC_USING_FENTRY and use that
macro over the users. This saves some #ifdef's in the assembly and
headers.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: <x86@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>
---
 arch/x86/include/asm/ftrace.h        | 11 +++++------
 arch/x86/include/asm/function_hook.h | 14 ++++++++++++++
 arch/x86/kernel/mcount_64.S          | 10 ++--------
 3 files changed, 21 insertions(+), 14 deletions(-)
 create mode 100644 arch/x86/include/asm/function_hook.h

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index eccd0ac6bc38..2bfbc6b7b45f 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -2,12 +2,13 @@
 #define _ASM_X86_FTRACE_H
 
 #ifdef CONFIG_FUNCTION_TRACER
-#ifdef CC_USING_FENTRY
-# define MCOUNT_ADDR		((unsigned long)(__fentry__))
-#else
-# define MCOUNT_ADDR		((unsigned long)(mcount))
+#ifndef CC_USING_FENTRY
 # define HAVE_FUNCTION_GRAPH_FP_TEST
 #endif
+
+#include <asm/function_hook.h>
+
+#define MCOUNT_ADDR		((unsigned long)(function_hook))
 #define MCOUNT_INSN_SIZE	5 /* sizeof mcount call */
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -17,9 +18,7 @@
 #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 
 #ifndef __ASSEMBLY__
-extern void mcount(void);
 extern atomic_t modifying_ftrace_code;
-extern void __fentry__(void);
 
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
diff --git a/arch/x86/include/asm/function_hook.h b/arch/x86/include/asm/function_hook.h
new file mode 100644
index 000000000000..9cc6c62efc8e
--- /dev/null
+++ b/arch/x86/include/asm/function_hook.h
@@ -0,0 +1,14 @@
+#ifndef ASM_FENTRY_H
+#define ASM_FENTRY_H
+
+#ifdef CC_USING_FENTRY
+# define function_hook	__fentry__
+#else
+# define function_hook	mcount
+#endif
+
+#ifndef __ASSEMBLY__
+extern void function_hook(void);
+#endif /* __ASSEMBLY__ */
+
+#endif /* ASM_FENTRY_H */
diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 7b0d3da52fb4..fb27f2f44513 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -7,6 +7,7 @@
 #include <linux/linkage.h>
 #include <asm/ptrace.h>
 #include <asm/ftrace.h>
+#include <asm/function_hook.h>
 #include <asm/export.h>
 
 
@@ -16,14 +17,6 @@
 
 #ifdef CONFIG_FUNCTION_TRACER
 
-#ifdef CC_USING_FENTRY
-# define function_hook	__fentry__
-EXPORT_SYMBOL(__fentry__)
-#else
-# define function_hook	mcount
-EXPORT_SYMBOL(mcount)
-#endif
-
 /* All cases save the original rbp (8 bytes) */
 #ifdef CONFIG_FRAME_POINTER
 # ifdef CC_USING_FENTRY
@@ -297,6 +290,7 @@ trace:
 	jmp fgraph_trace
 END(function_hook)
 #endif /* CONFIG_DYNAMIC_FTRACE */
+EXPORT_SYMBOL(function_hook)
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-- 
2.12.0