From f022cb3771222d1effa738d4cb74c67ed61e86cc Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Mon, 4 May 2015 00:45:24 +0200
Subject: [PATCH gnumach 02/10] use pcb stack

---
 i386/i386/locore.S | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/i386/i386/locore.S b/i386/i386/locore.S
index aa13c6b..f1ef044 100644
--- a/i386/i386/locore.S
+++ b/i386/i386/locore.S
@@ -592,7 +592,9 @@ ENTRY(thread_syscall_return)
 	or	$(KERNEL_STACK_SIZE-1),%ecx
 	movl	-3-IKS_SIZE(%ecx),%esp		/* switch back to PCB stack */
 	movl	%eax,R_EAX(%esp)		/* save return value */
-	/* XXX make this work with sysenter */
+	/* YYY make this work with sysenter */
+	cmpl	$0xffffffff, R_TRAPNO(%esp)
+	je	return_from_sysenter
 	jmp	_return_from_trap
 
 ENTRY(call_continuation)
@@ -1254,6 +1256,22 @@ ENTRY(sysenter_entry)
 	mov	%esp, %ebp		/* to access the sysenter stack */
 	cld				/* clear direction flag */
 
+	CPU_NUMBER(%edx)
+	movl	CX(EXT(kernel_stack),%edx),%ebx
+					/* get current kernel stack */
+	movl	%ebx, %ecx
+	or	$(KERNEL_STACK_SIZE-1),%ecx
+	movl	-3-IKS_SIZE(%ecx), %esp		/* switch to PCB stack */
+
+	/* Create trap save area.  */
+	subl	$(6 * 4), %esp		/* Unused.  We save the
+					   arguments in userspace.  */
+	pushl	$0x7fffffff		/* trap number */
+	pushl	$0x12345678			/* unused */
+	pushl	SE_STACK_POINTER(%ebp)  /* ecx */
+	pushl	SE_RETURN_ADDRESS(%ebp)	/* edx */
+	subl	$(5 * 4), %esp		/* Unused.  We save the
+					   arguments in userspace.  */
 	pushl	%ds			/* save the segment registers */
 	pushl	%es
 	pushl	%fs
@@ -1265,11 +1283,8 @@ ENTRY(sysenter_entry)
 	mov	%cx,%fs
 	mov	%cx,%gs
 
-	CPU_NUMBER(%edx)
-	movl	CX(EXT(kernel_stack),%edx),%ebx
-					/* get current kernel stack */
-	xchgl	%ebx, %esp		/* switch stacks */
-	pushl	%ebx			/* save sysenter sp */
+	xchgl	%ebx, %esp		/* switch to kernel stack */
+	pushl	%ebx			/* save pcb stack pointer */
 	movl	%esp,%ebx		/* save kernel sp for argument
 					   unwinding */
 
@@ -1328,16 +1343,15 @@ se_args_0:
 					/* call procedure */
 	cli				/* xxx: sti/cli where ? */
 	movl	%ebx, %esp		/* clean parameters from stack */
+	popl	%esp			/* switch to pcb stack */
 return_from_sysenter:
+	movl	%eax, R_EAX(%esp)	/* save return value */
 	/* xxx: process ast */
-	popl	%esp			/* restore sysenter sp */
 	popl	%gs			/* restore segment registers */
 	popl	%fs
 	popl	%es
 	popl	%ds
-
-	movl	SE_RETURN_ADDRESS(%ebp), %edx
-	movl	SE_STACK_POINTER(%ebp), %ecx
+	popa
 	sti				/* xxx: sti/cli where ? */
 	sysexit
 
-- 
2.1.4