[PATCH 6/6] ftrace/x86: Use Makefile logic instead of #ifdef for compiling ftrace_*.o

From: Steven Rostedt
Date: Tue Mar 21 2017 - 21:37:57 EST


From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

Currently ftrace_32.S and ftrace_64.S are compiled even when
CONFIG_FUNCTION_TRACER is not set. This means there's an unnecessary #ifdef
to protect the code. Instead of using preprocessor directives, only compile
those files when FUNCTION_TRACER is defined.

Link: 20170316210043.peycxdxktwwn6cid@treble">http://lkml.kernel.org/r/20170316210043.peycxdxktwwn6cid@treble
Suggested-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
arch/x86/kernel/Makefile | 4 ++--
arch/x86/kernel/ftrace_32.S | 3 ---
arch/x86/kernel/ftrace_64.S | 4 ----
3 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 55e8902c461f..4b994232cb57 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -46,8 +46,7 @@ obj-$(CONFIG_MODIFY_LDT_SYSCALL) += ldt.o
obj-y += setup.o x86_init.o i8259.o irqinit.o jump_label.o
obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-y += probe_roms.o
-obj-$(CONFIG_X86_64) += sys_x86_64.o ftrace_64.o
-obj-$(CONFIG_X86_32) += ftrace_32.o
+obj-$(CONFIG_X86_64) += sys_x86_64.o
obj-$(CONFIG_X86_ESPFIX64) += espfix_64.o
obj-$(CONFIG_SYSFS) += ksysfs.o
obj-y += bootflag.o e820.o
@@ -83,6 +82,7 @@ obj-y += apic/
obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups_32.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_LIVEPATCH) += livepatch.o
+obj-$(CONFIG_FUNCTION_TRACER) += ftrace_$(BITS).o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
obj-$(CONFIG_X86_TSC) += trace_clock.o
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index 4c1dc90ba381..de50c9084d16 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -10,8 +10,6 @@
#include <asm/export.h>
#include <asm/ftrace.h>

-#ifdef CONFIG_FUNCTION_TRACER
-
#ifdef CC_USING_FENTRY
# define function_hook __fentry__
EXPORT_SYMBOL(__fentry__)
@@ -208,7 +206,6 @@ ftrace_stub:
jmp ftrace_stub
END(function_hook)
#endif /* CONFIG_DYNAMIC_FTRACE */
-#endif /* CONFIG_FUNCTION_TRACER */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 7b0d3da52fb4..b9c46919d4fc 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -13,9 +13,6 @@
.code64
.section .entry.text, "ax"

-
-#ifdef CONFIG_FUNCTION_TRACER
-
#ifdef CC_USING_FENTRY
# define function_hook __fentry__
EXPORT_SYMBOL(__fentry__)
@@ -297,7 +294,6 @@ trace:
jmp fgraph_trace
END(function_hook)
#endif /* CONFIG_DYNAMIC_FTRACE */
-#endif /* CONFIG_FUNCTION_TRACER */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
--
2.10.2