From d0f4c16febf258ba8c0f917ac3ba935fc5459566 Mon Sep 17 00:00:00 2001
From: Andreas Krebbel <krebbel1@de.ibm.com>
Date: Fri, 6 Jan 2006 00:19:16 -0800
Subject: [PATCH] [PATCH] s390: add oprofile callgraph support

Signed-off-by: Andreas Krebbel <krebbel1@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 arch/s390/oprofile/Makefile    |  2 +-
 arch/s390/oprofile/backtrace.c | 79 ++++++++++++++++++++++++++++++++++
 arch/s390/oprofile/init.c      |  4 ++
 3 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 arch/s390/oprofile/backtrace.c

diff --git a/arch/s390/oprofile/Makefile b/arch/s390/oprofile/Makefile
index ec349276258a..537b2d840e69 100644
--- a/arch/s390/oprofile/Makefile
+++ b/arch/s390/oprofile/Makefile
@@ -6,4 +6,4 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
 		oprofilefs.o oprofile_stats.o  \
 		timer_int.o )
 
-oprofile-y				:= $(DRIVER_OBJS) init.o
+oprofile-y				:= $(DRIVER_OBJS) init.o backtrace.o
diff --git a/arch/s390/oprofile/backtrace.c b/arch/s390/oprofile/backtrace.c
new file mode 100644
index 000000000000..bc4b84a35cad
--- /dev/null
+++ b/arch/s390/oprofile/backtrace.c
@@ -0,0 +1,79 @@
+/**
+ * arch/s390/oprofile/backtrace.c
+ *
+ * S390 Version
+ *   Copyright (C) 2005 IBM Corporation, IBM Deutschland Entwicklung GmbH.
+ *   Author(s): Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
+ */
+
+#include <linux/oprofile.h>
+
+#include <asm/processor.h> /* for struct stack_frame */
+
+static unsigned long
+__show_trace(unsigned int *depth, unsigned long sp,
+	     unsigned long low, unsigned long high)
+{
+	struct stack_frame *sf;
+	struct pt_regs *regs;
+
+	while (*depth) {
+		sp = sp & PSW_ADDR_INSN;
+		if (sp < low || sp > high - sizeof(*sf))
+			return sp;
+		sf = (struct stack_frame *) sp;
+		(*depth)--;
+		oprofile_add_trace(sf->gprs[8] & PSW_ADDR_INSN);
+
+		/* Follow the backchain.  */
+		while (*depth) {
+			low = sp;
+			sp = sf->back_chain & PSW_ADDR_INSN;
+			if (!sp)
+				break;
+			if (sp <= low || sp > high - sizeof(*sf))
+				return sp;
+			sf = (struct stack_frame *) sp;
+			(*depth)--;
+			oprofile_add_trace(sf->gprs[8] & PSW_ADDR_INSN);
+
+		}
+
+		if (*depth == 0)
+			break;
+
+		/* Zero backchain detected, check for interrupt frame.  */
+		sp = (unsigned long) (sf + 1);
+		if (sp <= low || sp > high - sizeof(*regs))
+			return sp;
+		regs = (struct pt_regs *) sp;
+		(*depth)--;
+		oprofile_add_trace(sf->gprs[8] & PSW_ADDR_INSN);
+		low = sp;
+		sp = regs->gprs[15];
+	}
+	return sp;
+}
+
+void s390_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+	unsigned long head;
+	struct stack_frame* head_sf;
+
+	if (user_mode (regs))
+		return;
+
+	head = regs->gprs[15];
+	head_sf = (struct stack_frame*)head;
+
+	if (!head_sf->back_chain)
+		return;
+
+	head = head_sf->back_chain;
+
+	head = __show_trace(&depth, head, S390_lowcore.async_stack - ASYNC_SIZE,
+			    S390_lowcore.async_stack);
+
+	__show_trace(&depth, head, S390_lowcore.thread_info,
+		     S390_lowcore.thread_info + THREAD_SIZE);
+}
diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index a65ead0e200a..7a995113b918 100644
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -12,8 +12,12 @@
 #include <linux/init.h>
 #include <linux/errno.h>
 
+
+extern void s390_backtrace(struct pt_regs * const regs, unsigned int depth);
+
 int __init oprofile_arch_init(struct oprofile_operations* ops)
 {
+	ops->backtrace = s390_backtrace;
 	return -ENODEV;
 }