Blackfin: add CALLER_ADDR ftrace macros

Since GCC doesn't support __builtin_frame_address(n) where n!=0, add our
own function to walk the stack frame pointers.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/ftrace.h

@@ -10,4 +10,57 @@
 
 #define MCOUNT_INSN_SIZE	6 /* sizeof "[++sp] = rets; call __mcount;" */
 
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_FRAME_POINTER
+#include <linux/mm.h>
+
+extern inline void *return_address(unsigned int level)
+{
+	unsigned long *endstack, *fp, *ret_addr;
+	unsigned int current_level = 0;
+
+	if (level == 0)
+		return __builtin_return_address(0);
+
+	fp = (unsigned long *)__builtin_frame_address(0);
+	endstack = (unsigned long *)PAGE_ALIGN((unsigned long)&level);
+
+	while (((unsigned long)fp & 0x3) == 0 && fp &&
+	       (fp + 1) < endstack && current_level < level) {
+		fp = (unsigned long *)*fp;
+		current_level++;
+	}
+
+	if (((unsigned long)fp & 0x3) == 0 && fp &&
+	    (fp + 1) < endstack)
+		ret_addr = (unsigned long *)*(fp + 1);
+	else
+		ret_addr = NULL;
+
+	return ret_addr;
+}
+
+#else
+
+extern inline void *return_address(unsigned int level)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_FRAME_POINTER */
+
+#define HAVE_ARCH_CALLER_ADDR
+
+/* inline function or macro may lead to unexpected result */
+#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
+#define CALLER_ADDR1 ((unsigned long)return_address(1))
+#define CALLER_ADDR2 ((unsigned long)return_address(2))
+#define CALLER_ADDR3 ((unsigned long)return_address(3))
+#define CALLER_ADDR4 ((unsigned long)return_address(4))
+#define CALLER_ADDR5 ((unsigned long)return_address(5))
+#define CALLER_ADDR6 ((unsigned long)return_address(6))
+
+#endif /* __ASSEMBLY__ */
+
 #endif