From: Ben Gras <ben@minix3.org>
Date: Mon, 7 Jun 2010 22:24:21 +0000 (+0000)
Subject: fix from trunk for assert(ptproc == newptproc) without vm_stop on shutdown.
X-Git-Tag: v3.1.7~2
X-Git-Url: http://zhaoyanbai.com/repos/?a=commitdiff_plain;h=64b1205e6c56f778a99060b885c5d9a9ab0da3dd;p=minix.git

fix from trunk for assert(ptproc == newptproc) without vm_stop on shutdown.
---

diff --git a/kernel/arch/i386/klib.S b/kernel/arch/i386/klib.S
index 98d7171b2..4d99dd782 100644
--- a/kernel/arch/i386/klib.S
+++ b/kernel/arch/i386/klib.S
@@ -38,6 +38,7 @@
 .globl	_getcr3val
 .globl	_write_cr0	/* write a value in cr0 */
 .globl	_read_cr3
+.globl	_write_cr3
 .globl	_read_cr4
 .globl	_write_cr4
 
@@ -788,6 +789,22 @@ _write_cr4:
 0:
 	pop	%ebp
 	ret
+
+/*===========================================================================*/
+/*			      write_cr3					     */
+/*===========================================================================*/
+/* PUBLIC void write_cr3(unsigned long value); */
+_write_cr3:
+	push	%ebp
+	mov	%esp, %ebp
+	mov	8(%ebp), %eax
+
+	/* DO NOT CHANGE THE OPERAND!!! gas2ack does not handle it yet */
+	mov	%eax, %cr3
+
+	pop	%ebp
+	ret
+
 /*===========================================================================*/
 /*				getcr3val				     */
 /*===========================================================================*/
diff --git a/kernel/arch/i386/memory.c b/kernel/arch/i386/memory.c
index e3bc551be..ca93a298d 100644
--- a/kernel/arch/i386/memory.c
+++ b/kernel/arch/i386/memory.c
@@ -45,11 +45,25 @@ PUBLIC void vm_init(struct proc *newptproc)
 {
 	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);
 	vm_enable_paging();
 	vm_running = 1;
-
 }
 
 /* This function sets up a mapping from within the kernel's address
@@ -254,6 +268,11 @@ PRIVATE char *cr4_str(u32_t e)
 	return str;
 }
 
+PUBLIC void vm_stop(void)
+{
+	write_cr0(read_cr0() & ~I386_CR0_PG);
+}
+
 PRIVATE void vm_enable_paging(void)
 {
 	u32_t cr0, cr4;
diff --git a/kernel/arch/i386/proto.h b/kernel/arch/i386/proto.h
index 3acb7c42c..cdc40ab82 100644
--- a/kernel/arch/i386/proto.h
+++ b/kernel/arch/i386/proto.h
@@ -74,6 +74,7 @@ _PROTOTYPE( reg_t read_cr2, (void)					);
 _PROTOTYPE( void write_cr0, (unsigned long value)                       );
 _PROTOTYPE( unsigned long read_cr4, (void)                              );
 _PROTOTYPE( void write_cr4, (unsigned long value)                       );
+_PROTOTYPE( void write_cr3, (unsigned long value)                       );
 _PROTOTYPE( unsigned long read_cpu_flags, (void)                        );
 _PROTOTYPE( void phys_insb, (u16_t port, phys_bytes buf, size_t count)  );
 _PROTOTYPE( void phys_insw, (u16_t port, phys_bytes buf, size_t count)  );
diff --git a/kernel/proto.h b/kernel/proto.h
index 32ea89448..265d3a055 100644
--- a/kernel/proto.h
+++ b/kernel/proto.h
@@ -142,6 +142,7 @@ _PROTOTYPE( int data_copy_vmcheck, (struct proc *,
 	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));
 _PROTOTYPE( phys_bytes umap_remote, (const struct proc* rp, int seg,