diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9f748b5fb70182cdc6f31cf9e77dd68e2fdffb93..e34f95129f1642e615eca34a150f813b3a8f9b81 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -948,6 +948,12 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
 
 #define task_pt_regs(tsk)	((struct pt_regs *)(tsk)->thread.sp0 - 1)
 extern unsigned long KSTK_ESP(struct task_struct *task);
+
+/*
+ * User space RSP while inside the SYSCALL fast path
+ */
+DECLARE_PER_CPU(unsigned long, old_rsp);
+
 #endif /* CONFIG_X86_64 */
 
 extern void start_thread(struct pt_regs *regs, unsigned long new_ip,