1 files changed, 53 insertions, 33 deletions

diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index 8fc9daae47a2..da2d4d4c5b0e 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -36,6 +36,12 @@ 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)
+{
+	return task_pt_regs(state->task) == regs;
+}
+
 bool unwind_next_frame(struct unwind_state *state)
 {
 	struct stack_info *info = &state->stack_info;
@@ -46,15 +52,16 @@ bool unwind_next_frame(struct unwind_state *state)
 
 	regs = state->regs;
 	if (unlikely(regs)) {
-		sp = READ_ONCE_NOCHECK(regs->gprs[15]);
-		if (unlikely(outside_of_stack(state, sp))) {
-			if (!update_stack_info(state, sp))
-				goto out_err;
-		}
+		sp = state->sp;
 		sf = (struct stack_frame *) sp;
 		ip = READ_ONCE_NOCHECK(sf->gprs[8]);
 		reliable = false;
 		regs = NULL;
+		if (!__kernel_text_address(ip)) {
+			/* skip bogus %r14 */
+			state->regs = NULL;
+			return unwind_next_frame(state);
+		}
 	} else {
 		sf = (struct stack_frame *) state->sp;
 		sp = READ_ONCE_NOCHECK(sf->back_chain);
@@ -71,21 +78,25 @@ bool unwind_next_frame(struct unwind_state *state)
 			/* No back-chain, look for a pt_regs structure */
 			sp = state->sp + STACK_FRAME_OVERHEAD;
 			if (!on_stack(info, sp, sizeof(struct pt_regs)))
-				goto out_stop;
+				goto out_err;
 			regs = (struct pt_regs *) sp;
-			if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)
+			if (is_task_pt_regs(state, regs))
 				goto out_stop;
 			ip = READ_ONCE_NOCHECK(regs->psw.addr);
+			sp = READ_ONCE_NOCHECK(regs->gprs[15]);
+			if (unlikely(outside_of_stack(state, sp))) {
+				if (!update_stack_info(state, sp))
+					goto out_err;
+			}
 			reliable = true;
 		}
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, (void *) sp);
-#endif
+	/* Sanity check: ABI requires SP to be aligned 8 bytes. */
+	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;
@@ -103,13 +114,11 @@ out_stop:
 EXPORT_SYMBOL_GPL(unwind_next_frame);
 
 void __unwind_start(struct unwind_state *state, struct task_struct *task,
-		    struct pt_regs *regs, unsigned long sp)
+		    struct pt_regs *regs, unsigned long first_frame)
 {
 	struct stack_info *info = &state->stack_info;
-	unsigned long *mask = &state->stack_mask;
 	struct stack_frame *sf;
-	unsigned long ip;
-	bool reliable;
+	unsigned long ip, sp;
 
 	memset(state, 0, sizeof(*state));
 	state->task = task;
@@ -121,35 +130,46 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		return;
 	}
 
+	/* Get the instruction pointer from pt_regs or the stack frame */
+	if (regs) {
+		ip = regs->psw.addr;
+		sp = regs->gprs[15];
+	} else if (task == current) {
+		sp = current_frame_address();
+	} else {
+		sp = task->thread.ksp;
+	}
+
 	/* Get current stack pointer and initialize stack info */
-	if (get_stack_info(sp, task, info, mask) != 0 ||
-	    !on_stack(info, sp, sizeof(struct stack_frame))) {
+	if (!update_stack_info(state, sp)) {
 		/* Something is wrong with the stack pointer */
 		info->type = STACK_TYPE_UNKNOWN;
 		state->error = true;
 		return;
 	}
 
-	/* Get the instruction pointer from pt_regs or the stack frame */
-	if (regs) {
-		ip = READ_ONCE_NOCHECK(regs->psw.addr);
-		reliable = true;
-	} else {
-		sf = (struct stack_frame *) sp;
+	if (!regs) {
+		/* Stack frame is within valid stack */
+		sf = (struct stack_frame *)sp;
 		ip = READ_ONCE_NOCHECK(sf->gprs[8]);
-		reliable = false;
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, NULL);
-#endif
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL);
 
 	/* Update unwind state */
 	state->sp = sp;
 	state->ip = ip;
-	state->reliable = reliable;
+	state->reliable = true;
+
+	if (!first_frame)
+		return;
+	/* Skip through the call chain to the specified starting frame */
+	while (!unwind_done(state)) {
+		if (on_stack(&state->stack_info, first_frame, sizeof(struct stack_frame))) {
+			if (state->sp >= first_frame)
+				break;
+		}
+		unwind_next_frame(state);
+	}
 }
 EXPORT_SYMBOL_GPL(__unwind_start);