Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 460dcfb..f8fc4f8 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -6,70 +6,19 @@
  *  Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
  */
 
-#include <linux/sched.h>
-#include <linux/sched/debug.h>
 #include <linux/stacktrace.h>
-#include <linux/kallsyms.h>
-#include <linux/export.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
 
-static int __save_address(void *data, unsigned long address, int nosched)
+void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+		     struct task_struct *task, struct pt_regs *regs)
 {
-	struct stack_trace *trace = data;
+	struct unwind_state state;
+	unsigned long addr;
 
-	if (nosched && in_sched_functions(address))
-		return 0;
-	if (trace->skip > 0) {
-		trace->skip--;
-		return 0;
+	unwind_for_each_frame(&state, task, regs, 0) {
+		addr = unwind_get_return_address(&state);
+		if (!addr || !consume_entry(cookie, addr, false))
+			break;
 	}
-	if (trace->nr_entries < trace->max_entries) {
-		trace->entries[trace->nr_entries++] = address;
-		return 0;
-	}
-	return 1;
 }
-
-static int save_address(void *data, unsigned long address, int reliable)
-{
-	return __save_address(data, address, 0);
-}
-
-static int save_address_nosched(void *data, unsigned long address, int reliable)
-{
-	return __save_address(data, address, 1);
-}
-
-void save_stack_trace(struct stack_trace *trace)
-{
-	unsigned long sp;
-
-	sp = current_stack_pointer();
-	dump_trace(save_address, trace, NULL, sp);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
-}
-EXPORT_SYMBOL_GPL(save_stack_trace);
-
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
-{
-	unsigned long sp;
-
-	sp = tsk->thread.ksp;
-	if (tsk == current)
-		sp = current_stack_pointer();
-	dump_trace(save_address_nosched, trace, tsk, sp);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
-}
-EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
-
-void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
-{
-	unsigned long sp;
-
-	sp = kernel_stack_pointer(regs);
-	dump_trace(save_address, trace, NULL, sp);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
-}
-EXPORT_SYMBOL_GPL(save_stack_trace_regs);