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

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.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170316210043.peycxdxktwwn6cid@treble
Link: http://lkml.kernel.org/r/20170323143446.217684991@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 55e8902c461f46a43cd2f2f124d895b8783eb4de..4b994232cb5739f15eef17c69be00aa3b3bc5243 100644 (file)
--- 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 80518ec5b882aa64c465399600197a5e62f94e43..07f40359c9ea77ccc77a7efae9c079427a5f8a92 100644 (file)
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -8,8 +8,6 @@
 #include <asm/export.h>
 #include <asm/ftrace.h>
 
-#ifdef CONFIG_FUNCTION_TRACER
-
 #ifdef CC_USING_FENTRY
 # define function_hook __fentry__
 EXPORT_SYMBOL(__fentry__)
@@ -206,7 +204,6 @@ 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 d1be3cbe2cd4e5849bc90277253923f6ff91a48b..1dfac634bbf7f2a5470d0c12d2074a9cf71d4fc4 100644 (file)
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -11,9 +11,6 @@
        .code64
        .section .entry.text, "ax"
 
-
-#ifdef CONFIG_FUNCTION_TRACER
-
 #ifdef CC_USING_FENTRY
 # define function_hook __fentry__
 EXPORT_SYMBOL(__fentry__)
@@ -295,7 +292,6 @@ trace:
        jmp fgraph_trace
 END(function_hook)
 #endif /* CONFIG_DYNAMIC_FTRACE */
-#endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 ENTRY(ftrace_graph_caller)