libroot/ppc: Add missing stack_trace

src/system/libroot/os/arch/ppc/Jamfile

@@ -17,6 +17,7 @@ for architectureObject in [ MultiArchSubDirSetup ppc ] {
 			byteorder.S
 			compatibility.c	# only here until the places where those functions
 							# are used are fixed
+			stack_trace.cpp
 			stack_frame.c
 #			systeminfo.c
 			system_time.c

src/system/libroot/os/arch/ppc/stack_trace.cpp

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2015 Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Michael Lotz, mmlr@mlotz.ch
+ */
+
+#include <libroot_private.h>
+
+
+/*!	Captures a stack trace (the return addresses) of the current thread.
+	\param returnAddresses The array the return address shall be written to.
+	\param maxCount The maximum number of return addresses to be captured.
+	\param skipFrames The number of stack frames that shall be skipped.
+	\param stackBase The base address of the thread stack.
+	\param stackEnd The first address past the thread stack.
+	\return The number of return addresses written to the given array.
+*/
+int32
+__arch_get_stack_trace(addr_t* returnAddresses, int32 maxCount,
+	int32 skipFrames, addr_t stackBase, addr_t stackEnd)
+{
+	int32 count = 0;
+	addr_t basePointer = (addr_t)get_stack_frame();
+
+	while (basePointer != 0 && count < maxCount) {
+		if (basePointer < stackBase || basePointer >= stackEnd)
+			break;
+
+		struct stack_frame {
+			addr_t	previous;
+			addr_t	return_address;
+		};
+
+		stack_frame* frame = (stack_frame*)basePointer;
+
+		if (skipFrames <= 0)
+			returnAddresses[count++] = frame->return_address;
+		else
+			skipFrames--;
+
+		basePointer = frame->previous;
+	}
+
+	return count;
+}