1 files changed, 17 insertions, 4 deletions

diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index 9ce47cfe2303..92320d6f737c 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -43,6 +43,10 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                                    struct pt_regs *regs,
                                    struct unwind_frame_info *frame_info)
 {
+        /*
+         * synchronous unwinding (e.g. dump_stack)
+         *  - uses current values of SP and friends
+         */
         if (tsk == NULL && regs == NULL) {
                 unsigned long fp, sp, blink, ret;
                 frame_info->task = current;
@@ -61,12 +65,17 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                 frame_info->regs.r63 = ret;
                 frame_info->call_frame = 0;
         } else if (regs == NULL) {
+                /*
+                 * Asynchronous unwinding of sleeping task
+                 *  - Gets SP etc from task's pt_regs (saved bottom of kernel
+                 *    mode stack of task)
+                 */
 
                 frame_info->task = tsk;
 
-                frame_info->regs.r27 = KSTK_FP(tsk);
-                frame_info->regs.r28 = KSTK_ESP(tsk);
-                frame_info->regs.r31 = KSTK_BLINK(tsk);
+                frame_info->regs.r27 = TSK_K_FP(tsk);
+                frame_info->regs.r28 = TSK_K_ESP(tsk);
+                frame_info->regs.r31 = TSK_K_BLINK(tsk);
                 frame_info->regs.r63 = (unsigned int)__switch_to;
 
                 /* In the prologue of __switch_to, first FP is saved on stack
@@ -83,6 +92,10 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                 frame_info->call_frame = 0;
 
         } else {
+                /*
+                 * Asynchronous unwinding of intr/exception
+                 *  - Just uses the pt_regs passed
+                 */
                 frame_info->task = tsk;
 
                 frame_info->regs.r27 = regs->fp;
@@ -95,7 +108,7 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
 
 #endif
 
-static noinline unsigned int
+notrace noinline unsigned int
 arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
                 int (*consumer_fn) (unsigned int, void *), void *arg)
 {