tracing: make CALLER_ADDRx overwriteable

The current definition of CALLER_ADDRx isn't suitable for all platforms.
E.g. for ARM __builtin_return_address(N) doesn't work for N > 0 and
AFAIK for powerpc there are no frame pointers needed to have a working
__builtin_return_address.  This patch allows defining the CALLER_ADDRx
macros in <asm/ftrace.h> and let these take precedence.

Because now <asm/ftrace.h> is included unconditionally in
<linux/ftrace.h> all archs that don't already had this include get an
empty one for free.
Signed-off-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

arch/alpha/include/asm/ftrace.h

+/* empty */

arch/avr32/include/asm/ftrace.h

+/* empty */

arch/blackfin/include/asm/ftrace.h

+/* empty */

arch/cris/include/asm/ftrace.h

+/* empty */

arch/h8300/include/asm/ftrace.h

+/* empty */

arch/m68k/include/asm/ftrace.h

+/* empty */

arch/mips/include/asm/ftrace.h

+/* empty */

arch/parisc/include/asm/ftrace.h

+/* empty */

arch/um/include/asm/ftrace.h

+/* empty */

arch/xtensa/include/asm/ftrace.h

+/* empty */

include/asm-frv/ftrace.h

+/* empty */

include/asm-m32r/ftrace.h

+/* empty */

include/asm-mn10300/ftrace.h

+/* empty */

include/linux/ftrace.h

@@ -11,6 +11,8 @@
 #include <linux/bitops.h>
 #include <linux/sched.h>
 
+#include <asm/ftrace.h>
+
 #ifdef CONFIG_FUNCTION_TRACER
 
 extern int ftrace_enabled;
@@ -103,8 +105,6 @@ struct ftrace_func_command {
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
-#include <asm/ftrace.h>
 
 int ftrace_arch_code_modify_prepare(void);
 int ftrace_arch_code_modify_post_process(void);
@@ -282,8 +282,8 @@ static inline void __ftrace_enabled_restore(int enabled)
 #endif
 }
 
-#ifdef CONFIG_FRAME_POINTER
-/* TODO: need to fix this for ARM */
+#ifndef HAVE_ARCH_CALLER_ADDR
+# ifdef CONFIG_FRAME_POINTER
 #  define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
 #  define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
 #  define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
@@ -291,7 +291,7 @@ static inline void __ftrace_enabled_restore(int enabled)
 #  define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
 #  define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
 #  define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
-#else
+# else
 #  define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
 #  define CALLER_ADDR1 0UL
 #  define CALLER_ADDR2 0UL
@@ -299,7 +299,8 @@ static inline void __ftrace_enabled_restore(int enabled)
 #  define CALLER_ADDR4 0UL
 #  define CALLER_ADDR5 0UL
 #  define CALLER_ADDR6 0UL
-#endif
+# endif
+#endif /* ifndef HAVE_ARCH_CALLER_ADDR */
 
 #ifdef CONFIG_IRQSOFF_TRACER
   extern void time_hardirqs_on(unsigned long a0, unsigned long a1);