diff --git a/include/linux/compat.h b/include/linux/compat.h
index fe4ccd0..f964ef7 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -5,6 +5,8 @@
  * syscall compatibility layer.
  */
 
+#include <linux/types.h>
+
 #ifdef CONFIG_COMPAT
 
 #include <linux/stat.h>
@@ -719,9 +721,22 @@
 
 asmlinkage long compat_sys_fanotify_mark(int, unsigned int, __u32, __u32,
 					    int, const char __user *);
+
+/*
+ * For most but not all architectures, "am I in a compat syscall?" and
+ * "am I a compat task?" are the same question.  For architectures on which
+ * they aren't the same question, arch code can override in_compat_syscall.
+ */
+
+#ifndef in_compat_syscall
+static inline bool in_compat_syscall(void) { return is_compat_task(); }
+#endif
+
 #else
 
 #define is_compat_task() (0)
+static inline bool in_compat_syscall(void) { return false; }
 
 #endif /* CONFIG_COMPAT */
+
 #endif /* _LINUX_COMPAT_H */