ftrace, ia64: IA64 static ftrace support

IA64 ftrace suppport. In IA64, below code will be added in each function
if -pg is enabled.

alloc r40=ar.pfs,12,8,0
mov r43=r0;;
mov r42=b0
mov r41=r1
nop.i 0x0
br.call.sptk.many b0 = _mcount;;

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/ia64/Kconfig

@@ -21,6 +21,7 @@ config IA64
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
+	select HAVE_FUNCTION_TRACER
 	select HAVE_DMA_ATTRS
 	select HAVE_KVM
 	select HAVE_ARCH_TRACEHOOK

arch/ia64/include/asm/ftrace.h

@@ -0,0 +1,15 @@
+#ifndef _ASM_IA64_FTRACE_H
+#define _ASM_IA64_FTRACE_H
+
+#ifdef CONFIG_FUNCTION_TRACER
+#define MCOUNT_INSN_SIZE        32 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(unsigned long pfs, unsigned long r1, unsigned long b0, unsigned long r0);
+#define mcount _mcount
+
+#endif
+
+#endif /* CONFIG_FUNCTION_TRACER */
+
+#endif /* _ASM_IA64_FTRACE_H */

arch/ia64/kernel/entry.S

@@ -47,6 +47,7 @@
 #include <asm/processor.h>
 #include <asm/thread_info.h>
 #include <asm/unistd.h>
+#include <asm/ftrace.h>
 
 #include "minstate.h"
 
@@ -1404,6 +1405,54 @@ GLOBAL_ENTRY(unw_init_running)
 	br.ret.sptk.many rp
 END(unw_init_running)
 
+#ifdef CONFIG_FUNCTION_TRACER
+GLOBAL_ENTRY(_mcount)
+	movl r2 = ftrace_stub
+	movl r3 = ftrace_trace_function;;
+	ld8 r3 = [r3];;
+	ld8 r3 = [r3];;
+	cmp.eq p7,p0 = r2, r3
+(p7)	br.sptk.many ftrace_stub
+	;;
+
+	alloc loc0 = ar.pfs, 4, 4, 2, 0
+	;;
+	mov loc1 = b0
+	mov out0 = b0
+	mov loc2 = r8
+	mov loc3 = r15
+	;;
+	adds out0 = -MCOUNT_INSN_SIZE, out0
+	mov out1 = in2
+	mov b6 = r3
+
+	br.call.sptk.many b0 = b6
+	;;
+	mov ar.pfs = loc0
+	mov b0 = loc1
+	mov r8 = loc2
+	mov r15 = loc3
+	br ftrace_stub
+	;;
+END(_mcount)
+
+GLOBAL_ENTRY(ftrace_stub)
+	mov r3 = b0
+	movl r2 = _mcount_ret_helper
+	;;
+	mov b6 = r2
+	mov b7 = r3
+	br.ret.sptk.many b6
+
+_mcount_ret_helper:
+	mov b0 = r42
+	mov r1 = r41
+	mov ar.pfs = r40
+	br b7
+END(ftrace_stub)
+
+#endif /* CONFIG_FUNCTION_TRACER */
+
 	.rodata
 	.align 8
 	.globl sys_call_table

arch/ia64/kernel/ia64_ksyms.c

@@ -112,3 +112,9 @@ EXPORT_SYMBOL_GPL(esi_call_phys);
 #endif
 extern char ia64_ivt[];
 EXPORT_SYMBOL(ia64_ivt);
+
+#include <asm/ftrace.h>
+#ifdef CONFIG_FUNCTION_TRACER
+/* mcount is defined in assembly */
+EXPORT_SYMBOL(_mcount);
+#endif