[PATCH] arm: only build return_address() if needed

From: Ben Dooks <ben.dooks@codethink.co.uk>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@lists.codethink.co.uk,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Dooks <ben.dooks@codethink.co.uk>,
	Mark Charlebois <charlebm@gmail.com>,
	rmk@arm.linux.org.uk
Subject: [PATCH] arm: only build return_address() if needed
Date: Tue,  8 Oct 2019 16:53:49 +0100	[thread overview]
Message-ID: <20191008155349.28105-1-ben.dooks@codethink.co.uk> (raw)

The system currently warns if the config conditions for
building return_address in arch/arm/kernel/return_address.c
are not met, leaving just an EXPORT_SYMBOL_GPL(return_address)
of a function defined to be 'static linline'.
This is a result of aeea3592a13b ("ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h").

Since we're not going to build anything other than an exported
symbol for something that is already being defined to be an
inline-able return of NULL, just avoid building the code to
remove the following warning:

Fixes: aeea3592a13b ("ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h")
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
KernelVersion: 5.4-rc2
---
 arch/arm/kernel/Makefile         | 6 +++++-
 arch/arm/kernel/return_address.c | 4 ----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 8cad59465af3..818ed2f3c7b9 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -17,10 +17,14 @@ CFLAGS_REMOVE_return_address.o = -pg
 # Object file lists.
 
 obj-y		:= elf.o entry-common.o irq.o opcodes.o \
-		   process.o ptrace.o reboot.o return_address.o \
+		   process.o ptrace.o reboot.o \
 		   setup.o signal.o sigreturn_codes.o \
 		   stacktrace.o sys_arm.o time.o traps.o
 
+ifeq ($(CONFIG_ARM_UNWIND),n)
+obj-$(CONFIG_FRAME_POINTER)	+= return_address.o
+endif
+
 obj-$(CONFIG_ATAGS)		+= atags_parse.o
 obj-$(CONFIG_ATAGS_PROC)	+= atags_proc.o
 obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += atags_compat.o
diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
index b0d2f1fe891d..7b42ac010fdf 100644
--- a/arch/arm/kernel/return_address.c
+++ b/arch/arm/kernel/return_address.c
@@ -7,8 +7,6 @@
  */
 #include <linux/export.h>
 #include <linux/ftrace.h>
-
-#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
 #include <linux/sched.h>
 
 #include <asm/stacktrace.h>
@@ -53,6 +51,4 @@ void *return_address(unsigned int level)
 		return NULL;
 }
 
-#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
-
 EXPORT_SYMBOL_GPL(return_address);
-- 
2.23.0


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