diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 73a522d53b53..8ae7ffda8f98 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -981,7 +981,7 @@ ENTRY(\sym)
 
 	call	\do_sym
 
-	jmp	error_exit			/* %ebx: no swapgs flag */
+	jmp	error_exit
 	.endif
 END(\sym)
 .endm
@@ -1222,7 +1222,6 @@ END(paranoid_exit)
 
 /*
  * Save all registers in pt_regs, and switch GS if needed.
- * Return: EBX=0: came from user mode; EBX=1: otherwise
  */
 ENTRY(error_entry)
 	UNWIND_HINT_FUNC
@@ -1269,7 +1268,6 @@ ENTRY(error_entry)
 	 * for these here too.
 	 */
 .Lerror_kernelspace:
-	incl	%ebx
 	leaq	native_irq_return_iret(%rip), %rcx
 	cmpq	%rcx, RIP+8(%rsp)
 	je	.Lerror_bad_iret
@@ -1303,28 +1301,20 @@ ENTRY(error_entry)
 
 	/*
 	 * Pretend that the exception came from user mode: set up pt_regs
-	 * as if we faulted immediately after IRET and clear EBX so that
-	 * error_exit knows that we will be returning to user mode.
+	 * as if we faulted immediately after IRET.
 	 */
 	mov	%rsp, %rdi
 	call	fixup_bad_iret
 	mov	%rax, %rsp
-	decl	%ebx
 	jmp	.Lerror_entry_from_usermode_after_swapgs
 END(error_entry)
 
-
-/*
- * On entry, EBX is a "return to kernel mode" flag:
- *   1: already in kernel mode, don't need SWAPGS
- *   0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode
- */
 ENTRY(error_exit)
 	UNWIND_HINT_REGS
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF
-	testl	%ebx, %ebx
-	jnz	retint_kernel
+	testb	$3, CS(%rsp)
+	jz	retint_kernel
 	jmp	retint_user
 END(error_exit)