x86/asm/entry/64: Migrate error and IRQ exit work to C and remove old assembly code

Signed-off-by: Andy Lutomirski <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/entry/entry_64.S

···
 
 	testb	$3, CS(%rsp)
 	jz	1f
+
+	/*
+	 * IRQ from user mode.  Switch to kernel gsbase and inform context
+	 * tracking that we're in kernel mode.
+	 */
 	SWAPGS
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+
 1:
 	/*
 	 * Save previous stack pointer, optionally switch to interrupt stack.
···
 
 	testb	$3, CS(%rsp)
 	jz	retint_kernel
+
 	/* Interrupt came from user space */
-GLOBAL(retint_user)
-	GET_THREAD_INFO(%rcx)
-
-	/* %rcx: thread info. Interrupts are off. */
-retint_with_reschedule:
-	movl	$_TIF_WORK_MASK, %edi
-retint_check:
 	LOCKDEP_SYS_EXIT_IRQ
-	movl	TI_flags(%rcx), %edx
-	andl	%edi, %edx
-	jnz	retint_careful
-
-retint_swapgs:					/* return to user-space */
-	/*
-	 * The iretq could re-enable interrupts:
-	 */
-	DISABLE_INTERRUPTS(CLBR_ANY)
+GLOBAL(retint_user)
+	mov	%rsp,%rdi
+	call	prepare_exit_to_usermode
 	TRACE_IRQS_IRETQ
-
 	SWAPGS
 	jmp	restore_regs_and_iret
 
···
 	popq	%rax
 	jmp	native_irq_return_iret
 #endif
-
-	/* edi: workmask, edx: work */
-retint_careful:
-	bt	$TIF_NEED_RESCHED, %edx
-	jnc	retint_signal
-	TRACE_IRQS_ON
-	ENABLE_INTERRUPTS(CLBR_NONE)
-	pushq	%rdi
-	SCHEDULE_USER
-	popq	%rdi
-	GET_THREAD_INFO(%rcx)
-	DISABLE_INTERRUPTS(CLBR_NONE)
-	TRACE_IRQS_OFF
-	jmp	retint_check
-
-retint_signal:
-	testl	$_TIF_DO_NOTIFY_MASK, %edx
-	jz	retint_swapgs
-	TRACE_IRQS_ON
-	ENABLE_INTERRUPTS(CLBR_NONE)
-	movq	$-1, ORIG_RAX(%rsp)
-	xorl	%esi, %esi			/* oldset */
-	movq	%rsp, %rdi			/* &pt_regs */
-	call	do_notify_resume
-	DISABLE_INTERRUPTS(CLBR_NONE)
-	TRACE_IRQS_OFF
-	GET_THREAD_INFO(%rcx)
-	jmp	retint_with_reschedule
-
 END(common_interrupt)
 
 /*
···
 	SWAPGS
 
 .Lerror_entry_from_usermode_after_swapgs:
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+
 .Lerror_entry_done:
+
 	TRACE_IRQS_OFF
 	ret
 

arch/x86/entry/entry_64_compat.S

···
 	DISABLE_INTERRUPTS(CLBR_NONE)
 	TRACE_IRQS_OFF
 
+	/* Now finish entering normal kernel mode. */
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+
 	/* And exit again. */
 	jmp retint_user