Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/s390/kernel/entry.h b/arch/s390/kernel/entry.h
index 472fa2f..b2956d4 100644
--- a/arch/s390/kernel/entry.h
+++ b/arch/s390/kernel/entry.h
@@ -63,9 +63,8 @@
 void die(struct pt_regs *regs, const char *str);
 int setup_profiling_timer(unsigned int multiplier);
 void __init time_init(void);
-int pfn_is_nosave(unsigned long);
 void s390_early_resume(void);
-unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip);
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long sp, unsigned long ip);
 
 struct s390_mmap_arg_struct;
 struct fadvise64_64_args;
@@ -86,4 +85,7 @@
 void gs_load_bc_cb(struct pt_regs *regs);
 void set_fs_fixup(void);
 
+unsigned long stack_alloc(void);
+void stack_free(unsigned long stack);
+
 #endif /* _ENTRY_H */