From ce4fd0c0fb1b9b8998e22b5aab044afffb14d40f Mon Sep 17 00:00:00 2001
From: Tomas Hruby <tom@minix3.org>
Date: Wed, 15 Sep 2010 14:09:41 +0000
Subject: [PATCH] Enable paging - some more code reshuffling

---
 kernel/arch/i386/memory.c | 47 +++++++++++++++++++--------------------
 kernel/proto.h            |  1 -
 kernel/system/do_vmctl.c  |  6 ++---
 3 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/kernel/arch/i386/memory.c b/kernel/arch/i386/memory.c
index 6d1394cae..9875e9c05 100644
--- a/kernel/arch/i386/memory.c
+++ b/kernel/arch/i386/memory.c
@@ -38,32 +38,11 @@ FORWARD _PROTOTYPE( u32_t phys_get32, (phys_bytes v)			);
 FORWARD _PROTOTYPE( void vm_enable_paging, (void)			);
 
 	
-/* *** Internal VM Functions *** */
-
-PUBLIC void vm_init(struct proc *newptproc)
+PUBLIC void segmentation2paging(struct proc * current)
 {
-	if(vm_running)
-		panic("vm_init: vm_running");
-
-	/* switch_address_space() checks what is in cr3, and doesn't do
-	 * anything if it's the same as the cr3 of its argument, newptproc.
-	 * If MINIX was previously booted, this could very well be the case.
-	 *
-	 * The first time switch_address_space() is called, we want to
-	 * force it to do something (load cr3 and set newptproc), so we
-	 * zero cr3, and force paging off to make that a safe thing to do.
-	 *
-	 * After that, vm_enable_paging() enables paging with the page table
-	 * of newptproc loaded.
-	 */
-
-	vm_stop();
-	write_cr3(0);
-	switch_address_space(newptproc);
-	assert(ptproc == newptproc);
-	catch_pagefaults = 0;
+	/* switch to the current process page tables before turning paging on */
+	switch_address_space(current);
 	vm_enable_paging();
-	vm_running = 1;
 }
 
 /* This function sets up a mapping from within the kernel's address
@@ -1042,6 +1021,26 @@ PUBLIC int arch_enable_paging(struct proc * caller, const message * m_ptr)
 	struct vm_ep_data ep_data;
 	int r;
 
+	/* switch_address_space() checks what is in cr3, and do nothing if it's
+	 * the same as the cr3 of its argument, newptproc.  If MINIX was
+	 * previously booted, this could very well be the case.
+	 *
+	 * The first time switch_address_space() is called, we want to
+	 * force it to do something (load cr3 and set newptproc), so we
+	 * zero cr3, and force paging off to make that a safe thing to do.
+	 *
+	 * After that, segmentation2paging() enables paging with the page table
+	 * of caller loaded.
+	 */
+
+	vm_stop();
+	write_cr3(0);
+
+	/* switch from segmentation only to paging */
+	segmentation2paging(caller);
+
+	vm_running = 1;
+
 	/*
 	 * copy the extra data associated with the call from userspace
 	 */
diff --git a/kernel/proto.h b/kernel/proto.h
index 4f71d7c94..fb84aa51c 100644
--- a/kernel/proto.h
+++ b/kernel/proto.h
@@ -152,7 +152,6 @@ _PROTOTYPE( int data_copy_vmcheck, (struct proc *,
 	endpoint_t from, vir_bytes from_addr,
 	endpoint_t to, vir_bytes to_addr, size_t bytes));
 _PROTOTYPE( void alloc_segments, (struct proc *rp)                      );
-_PROTOTYPE( void vm_init, (struct proc *first)        			);
 _PROTOTYPE( void vm_stop, (void)        				);
 _PROTOTYPE( phys_bytes umap_local, (register struct proc *rp, int seg,
 	vir_bytes vir_addr, vir_bytes bytes));
diff --git a/kernel/system/do_vmctl.c b/kernel/system/do_vmctl.c
index c5fdbd865..82673deac 100644
--- a/kernel/system/do_vmctl.c
+++ b/kernel/system/do_vmctl.c
@@ -123,10 +123,10 @@ PUBLIC int do_vmctl(struct proc * caller, message * m_ptr)
 	case VMCTL_ENABLE_PAGING:
 		if(vm_running) 
 			panic("do_vmctl: paging already enabled");
-		vm_init(p);
-		if(!vm_running)
+		if (arch_enable_paging(caller, m_ptr) != OK)
 			panic("do_vmctl: paging enabling failed");
-		return arch_enable_paging(caller, m_ptr);
+		return OK;
+
 	case VMCTL_KERN_PHYSMAP:
 	{
 		int i = m_ptr->SVMCTL_VALUE;
-- 
2.44.0