1 files changed, 19 insertions, 12 deletions

diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index da2d4d4c5b0e..cd44be2b6ce8 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -36,12 +36,21 @@ static bool update_stack_info(struct unwind_state *state, unsigned long sp)
 	return true;
 }
 
-static inline bool is_task_pt_regs(struct unwind_state *state,
-				   struct pt_regs *regs)
+static inline bool is_final_pt_regs(struct unwind_state *state,
+				    struct pt_regs *regs)
 {
-	return task_pt_regs(state->task) == regs;
+	/* user mode or kernel thread pt_regs at the bottom of task stack */
+	if (task_pt_regs(state->task) == regs)
+		return true;
+
+	/* user mode pt_regs at the bottom of irq stack */
+	return state->stack_info.type == STACK_TYPE_IRQ &&
+	       state->stack_info.end - sizeof(struct pt_regs) == (unsigned long)regs &&
+	       READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE;
 }
 
+/* Avoid KMSAN false positives from touching uninitialized frames. */
+__no_kmsan_checks
 bool unwind_next_frame(struct unwind_state *state)
 {
 	struct stack_info *info = &state->stack_info;
@@ -57,8 +66,8 @@ bool unwind_next_frame(struct unwind_state *state)
 		ip = READ_ONCE_NOCHECK(sf->gprs[8]);
 		reliable = false;
 		regs = NULL;
-		if (!__kernel_text_address(ip)) {
-			/* skip bogus %r14 */
+		/* skip bogus %r14 or if is the same as regs->psw.addr */
+		if (!__kernel_text_address(ip) || state->ip == unwind_recover_ret_addr(state, ip)) {
 			state->regs = NULL;
 			return unwind_next_frame(state);
 		}
@@ -80,7 +89,7 @@ bool unwind_next_frame(struct unwind_state *state)
 			if (!on_stack(info, sp, sizeof(struct pt_regs)))
 				goto out_err;
 			regs = (struct pt_regs *) sp;
-			if (is_task_pt_regs(state, regs))
+			if (is_final_pt_regs(state, regs))
 				goto out_stop;
 			ip = READ_ONCE_NOCHECK(regs->psw.addr);
 			sp = READ_ONCE_NOCHECK(regs->gprs[15]);
@@ -96,13 +105,11 @@ bool unwind_next_frame(struct unwind_state *state)
 	if (sp & 0x7)
 		goto out_err;
 
-	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp);
-
 	/* Update unwind state */
 	state->sp = sp;
-	state->ip = ip;
 	state->regs = regs;
 	state->reliable = reliable;
+	state->ip = unwind_recover_ret_addr(state, ip);
 	return true;
 
 out_err:
@@ -113,6 +120,8 @@ out_stop:
 }
 EXPORT_SYMBOL_GPL(unwind_next_frame);
 
+/* Avoid KMSAN false positives from touching uninitialized frames. */
+__no_kmsan_checks
 void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		    struct pt_regs *regs, unsigned long first_frame)
 {
@@ -154,12 +163,10 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		ip = READ_ONCE_NOCHECK(sf->gprs[8]);
 	}
 
-	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL);
-
 	/* Update unwind state */
 	state->sp = sp;
-	state->ip = ip;
 	state->reliable = true;
+	state->ip = unwind_recover_ret_addr(state, ip);
 
 	if (!first_frame)
 		return;