@@ -5521,6 +5521,12 @@
 	unknown_nmi_panic
 			[X86] Cause panic on unknown NMI.
 
+	unwind_debug	[X86-64]
+			Enable unwinder debug output.  This can be
+			useful for debugging certain unwinder error
+			conditions, including corrupt stacks and
+			bad/missing unwinder metadata.
+
 	usbcore.authorized_default=
 			[USB] Default USB device authorization:
 			(default -1 = authorized except for wireless USB,

@@ -123,4 +123,7 @@ static inline bool task_on_another_cpu(struct task_struct *task)
 #endif
 }
 
+extern bool unwind_debug __ro_after_init;
+void unwind_dump(struct unwind_state *state);
+
 #endif /* _ASM_X86_UNWIND_H */

@@ -29,6 +29,42 @@ static int die_counter;
 
 static struct pt_regs exec_summary_regs;
 
+bool unwind_debug __ro_after_init;
+static int __init unwind_debug_cmdline(char *str)
+{
+	unwind_debug = true;
+	return 0;
+}
+early_param("unwind_debug", unwind_debug_cmdline);
+
+void unwind_dump(struct unwind_state *state)
+{
+	unsigned long word, *sp;
+	struct stack_info stack_info = {0};
+	unsigned long visit_mask = 0;
+
+	printk_deferred("unwinder dump: stack type:%d next_sp:%p mask:0x%lx graph_idx:%d\n",
+			state->stack_info.type, state->stack_info.next_sp,
+			state->stack_mask, state->graph_idx);
+
+	sp = state->task == current ? __builtin_frame_address(0)
+				    : (void *)state->task->thread.sp;
+
+	for (; sp; sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
+		if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
+			break;
+
+		for (; sp < stack_info.end; sp++) {
+
+			word = READ_ONCE_NOCHECK(*sp);
+
+			printk_deferred("%0*lx: %0*lx (%pB)\n", BITS_PER_LONG/4,
+					(unsigned long)sp, BITS_PER_LONG/4,
+					word, (void *)word);
+		}
+	}
+}
+
 bool noinstr in_task_stack(unsigned long *stack, struct task_struct *task,
 			   struct stack_info *info)
 {

@@ -301,6 +337,9 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		if (stack_name)
 			printk("%s </%s>\n", log_lvl, stack_name);
 	}
+
+	if (unwind_debug)
+		unwind_dump(&state);
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp,

@@ -28,48 +28,6 @@ unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
 	return state->regs ? &state->regs->ip : state->bp + 1;
 }
 
-static void unwind_dump(struct unwind_state *state)
-{
-	static bool dumped_before = false;
-	bool prev_zero, zero = false;
-	unsigned long word, *sp;
-	struct stack_info stack_info = {0};
-	unsigned long visit_mask = 0;
-
-	if (dumped_before)
-		return;
-
-	dumped_before = true;
-
-	printk_deferred("unwind stack type:%d next_sp:%p mask:0x%lx graph_idx:%d\n",
-			state->stack_info.type, state->stack_info.next_sp,
-			state->stack_mask, state->graph_idx);
-
-	for (sp = PTR_ALIGN(state->orig_sp, sizeof(long)); sp;
-	     sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
-		if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
-			break;
-
-		for (; sp < stack_info.end; sp++) {
-
-			word = READ_ONCE_NOCHECK(*sp);
-
-			prev_zero = zero;
-			zero = word == 0;
-
-			if (zero) {
-				if (!prev_zero)
-					printk_deferred("%p: %0*x ...\n",
-							sp, BITS_PER_LONG/4, 0);
-				continue;
-			}
-
-			printk_deferred("%p: %0*lx (%pB)\n",
-					sp, BITS_PER_LONG/4, word, (void *)word);
-		}
-	}
-}
-
 static bool in_entry_code(unsigned long ip)
 {
 	char *addr = (char *)ip;

@@ -244,7 +202,6 @@ static bool update_stack_state(struct unwind_state *state,
 						  addr, addr_p);
 	}
 
-	/* Save the original stack pointer for unwind_dump(): */
 	if (!state->orig_sp)
 		state->orig_sp = frame;
 

@@ -346,13 +303,17 @@ bool unwind_next_frame(struct unwind_state *state)
 			"WARNING: kernel stack regs at %p in %s:%d has bad 'bp' value %p\n",
 			state->regs, state->task->comm,
 			state->task->pid, next_bp);
-		unwind_dump(state);
+
+		if (unwind_debug)
+			unwind_dump(state);
 	} else {
 		printk_deferred_once(KERN_WARNING
 			"WARNING: kernel stack frame pointer at %p in %s:%d has bad value %p\n",
 			state->bp, state->task->comm,
 			state->task->pid, next_bp);
-		unwind_dump(state);
+
+		if (unwind_debug)
+			unwind_dump(state);
 	}
 the_end:
 	state->stack_info.type = STACK_TYPE_UNKNOWN;

@@ -13,8 +13,11 @@
 
 #define orc_warn_current(args...)					\
 ({									\
-	if (state->task == current)					\
+	if (state->task == current) {					\
 		orc_warn(args);						\
+		if (unwind_debug)					\
+			unwind_dump(state);				\
+	}								\
 })
 
 extern int __start_orc_unwind_ip[];