ftrace: store mcount address in rec->ip

Record the address of the mcount call-site. Currently all archs except sparc64
record the address of the instruction following the mcount call-site. Some
general cleanups are entailed. Storing mcount addresses in rec->ip enables
looking them up in the kprobe hash table later on to check if they're kprobe'd.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: davem@davemloft.net
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/powerpc/kernel/entry_64.S

@@ -31,6 +31,7 @@
 #include <asm/bug.h>
 #include <asm/ptrace.h>
 #include <asm/irqflags.h>
+#include <asm/ftrace.h>
 
 /*
  * System calls.
@@ -879,6 +880,7 @@ _GLOBAL(_mcount)
 	mflr	r3
 	stdu	r1, -112(r1)
 	std	r3, 128(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	.globl mcount_call
 mcount_call:
 	bl	ftrace_stub
@@ -895,6 +897,7 @@ _GLOBAL(ftrace_caller)
 	stdu	r1, -112(r1)
 	std	r3, 128(r1)
 	ld	r4, 16(r11)
+	subi	r3, r3, MCOUNT_INSN_SIZE
 .globl ftrace_call
 ftrace_call:
 	bl	ftrace_stub
@@ -916,7 +919,7 @@ _GLOBAL(_mcount)
 	std	r3, 128(r1)
 	ld	r4, 16(r11)
 
-
+	subi	r3, r3, MCOUNT_INSN_SIZE
 	LOAD_REG_ADDR(r5,ftrace_trace_function)
 	ld	r5,0(r5)
 	ld	r5,0(r5)