Merge tag 'docs-5.11-2' of git://git.lwn.net/linux

[linux-2.6-microblaze.git] / arch / arc / kernel / stacktrace.c

diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index b23986f..f73da20 100644 (file)
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -38,15 +38,27 @@
 
 #ifdef CONFIG_ARC_DW2_UNWIND
 
-static void seed_unwind_frame_info(struct task_struct *tsk,
-                                  struct pt_regs *regs,
-                                  struct unwind_frame_info *frame_info)
+static int
+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) {
+       if (regs) {
+               /*
+                * Asynchronous unwinding of intr/exception
+                *  - Just uses the pt_regs passed
+                */
+               frame_info->task = tsk;
+
+               frame_info->regs.r27 = regs->fp;
+               frame_info->regs.r28 = regs->sp;
+               frame_info->regs.r31 = regs->blink;
+               frame_info->regs.r63 = regs->ret;
+               frame_info->call_frame = 0;
+       } else if (tsk == NULL || tsk == current) {
+               /*
+                * synchronous unwinding (e.g. dump_stack)
+                *  - uses current values of SP and friends
+                */
                unsigned long fp, sp, blink, ret;
                frame_info->task = current;
 
@@ -63,13 +75,17 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                frame_info->regs.r31 = blink;
                frame_info->regs.r63 = ret;
                frame_info->call_frame = 0;
-       } else if (regs == NULL) {
+       } else {
                /*
-                * Asynchronous unwinding of sleeping task
-                *  - Gets SP etc from task's pt_regs (saved bottom of kernel
-                *    mode stack of task)
+                * Asynchronous unwinding of a likely sleeping task
+                *  - first ensure it is actually sleeping
+                *  - if so, it will be in __switch_to, kernel mode SP of task
+                *    is safe-kept and BLINK at a well known location in there
                 */
 
+               if (tsk->state == TASK_RUNNING)
+                       return -1;
+
                frame_info->task = tsk;
 
                frame_info->regs.r27 = TSK_K_FP(tsk);
@@ -90,19 +106,8 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                frame_info->regs.r28 += 60;
                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;
-               frame_info->regs.r28 = regs->sp;
-               frame_info->regs.r31 = regs->blink;
-               frame_info->regs.r63 = regs->ret;
-               frame_info->call_frame = 0;
        }
+       return 0;
 }
 
 #endif
@@ -116,7 +121,8 @@ arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
        unsigned int address;
        struct unwind_frame_info frame_info;
 
-       seed_unwind_frame_info(tsk, regs, &frame_info);
+       if (seed_unwind_frame_info(tsk, regs, &frame_info))
+               return 0;
 
        while (1) {
                address = UNW_PC(&frame_info);