2 files changed, 44 insertions, 7 deletions

diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 4e547296831d..52312cb5dbe2 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -47,9 +47,6 @@ struct thread_struct {
 /* Forward declaration, a strange C thing */
 struct task_struct;
 
-/* Return saved PC of a blocked thread  */
-unsigned long thread_saved_pc(struct task_struct *t);
-
 #define task_pt_regs(p) \
         ((struct pt_regs *)(THREAD_SIZE + (void *)task_stack_page(p)) - 1)
 
@@ -72,18 +69,21 @@ unsigned long thread_saved_pc(struct task_struct *t);
 #define release_segments(mm)        do { } while (0)
 
 #define KSTK_EIP(tsk)   (task_pt_regs(tsk)->ret)
+#define KSTK_ESP(tsk)   (task_pt_regs(tsk)->sp)
 
 /*
  * Where abouts of Task's sp, fp, blink when it was last seen in kernel mode.
  * Look in process.c for details of kernel stack layout
  */
-#define KSTK_ESP(tsk)   (tsk->thread.ksp)
+#define TSK_K_ESP(tsk)          (tsk->thread.ksp)
 
-#define KSTK_REG(tsk, off)      (*((unsigned int *)(KSTK_ESP(tsk) + \
+#define TSK_K_REG(tsk, off)     (*((unsigned int *)(TSK_K_ESP(tsk) + \
                                         sizeof(struct callee_regs) + off)))
 
-#define KSTK_BLINK(tsk) KSTK_REG(tsk, 4)
-#define KSTK_FP(tsk)    KSTK_REG(tsk, 0)
+#define TSK_K_BLINK(tsk)        TSK_K_REG(tsk, 4)
+#define TSK_K_FP(tsk)           TSK_K_REG(tsk, 0)
+
+#define thread_saved_pc(tsk)    TSK_K_BLINK(tsk)
 
 extern void start_thread(struct pt_regs * regs, unsigned long pc,
                          unsigned long usp);
diff --git a/arch/arc/include/asm/stacktrace.h b/arch/arc/include/asm/stacktrace.h
new file mode 100644
index 000000000000..b29b6064ea14
--- /dev/null
+++ b/arch/arc/include/asm/stacktrace.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
+ * Copyright (C) 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_STACKTRACE_H
+#define __ASM_STACKTRACE_H
+
+#include <linux/sched.h>
+
+/**
+ * arc_unwind_core - Unwind the kernel mode stack for an execution context
+ * @tsk:                NULL for current task, specific task otherwise
+ * @regs:               pt_regs used to seed the unwinder {SP, FP, BLINK, PC}
+ *                      If NULL, use pt_regs of @tsk (if !NULL) otherwise
+ *                      use the current values of {SP, FP, BLINK, PC}
+ * @consumer_fn:        Callback invoked for each frame unwound
+ *                      Returns 0 to continue unwinding, -1 to stop
+ * @arg:                Arg to callback
+ *
+ * Returns the address of first function in stack
+ *
+ * Semantics:
+ *  - synchronous unwinding (e.g. dump_stack): @tsk  NULL, @regs  NULL
+ *  - Asynchronous unwinding of sleeping task: @tsk !NULL, @regs  NULL
+ *  - Asynchronous unwinding of intr/excp etc: @tsk !NULL, @regs !NULL
+ */
+notrace noinline unsigned int arc_unwind_core(
+        struct task_struct *tsk, struct pt_regs *regs,
+        int (*consumer_fn) (unsigned int, void *),
+        void *arg);
+
+#endif /* __ASM_STACKTRACE_H */