From: Ben Gras <ben@minix3.org>
Date: Mon, 5 Oct 2009 15:22:31 +0000 (+0000)
Subject: thanks to tomas: fix for level0() race condition - global variable can
X-Git-Tag: v3.1.5~29
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/zpipe.c?a=commitdiff_plain;h=30804b9ed7e915adffbc1b39370ba049383a3869;p=minix.git

thanks to tomas: fix for level0() race condition - global variable can
be used concurrently.  pass the function in eax instead; this gets rid
of the global variable.  also execute the function directly if we're
already trapped into the kernel.

revert of u32_t endpoint_t to int (some code assumes endpoints are
negative for negative slot numbers).
---

diff --git a/kernel/arch/i386/klib386.s b/kernel/arch/i386/klib386.s
index d506059f9..ed0cc22cb 100755
--- a/kernel/arch/i386/klib386.s
+++ b/kernel/arch/i386/klib386.s
@@ -489,11 +489,11 @@ idt_zero:	.data4	0, 0
 _idle_task:
 ! This task is called when the system has nothing else to do.  The HLT
 ! instruction puts the processor in a state where it draws minimum power.
-	push	halt
+	push	_halt
 	call	_level0		! level0(halt)
 	pop	eax
 	jmp	_idle_task
-halt:
+_halt:
 	sti
 	hlt
 	cli
@@ -508,10 +508,15 @@ halt:
 !
 _level0:
 	mov	eax, 4(esp)
-	mov	(_level0_func), eax
+	cmpb	(_k_reenter), -1
+	jne	direct
 	int	LEVEL0_VECTOR
 	ret
 
+direct:
+	call	eax
+	ret
+
 
 !*===========================================================================*
 !*			      read_flags					     *
diff --git a/kernel/arch/i386/memory.c b/kernel/arch/i386/memory.c
index c5eb9de6e..013e609db 100644
--- a/kernel/arch/i386/memory.c
+++ b/kernel/arch/i386/memory.c
@@ -36,7 +36,6 @@ PRIVATE int nfreepdes = 0, freepdes[WANT_FREEPDES], inusepde = NOPDE;
 #define HASPT(procptr) ((procptr)->p_seg.p_cr3 != 0)
 
 FORWARD _PROTOTYPE( u32_t phys_get32, (vir_bytes v)			);
-FORWARD _PROTOTYPE( void set_cr3, (void)				);
 FORWARD _PROTOTYPE( void vm_enable_paging, (void)			);
 
 	
@@ -241,26 +240,23 @@ phys_bytes addr;
 
 PRIVATE u32_t vm_cr3;	/* temp arg to level0() func */
 
+PRIVATE void set_cr3()
+{
+	write_cr3(vm_cr3);
+}
+
 PUBLIC void vm_set_cr3(struct proc *newptproc)
 {
 	int u = 0;
 	if(!intr_disabled()) { lock; u = 1; }
 	vm_cr3= newptproc->p_seg.p_cr3;
 	if(vm_cr3) {
-		vmassert(intr_disabled());
 		level0(set_cr3);
-		vmassert(intr_disabled());
 		ptproc = newptproc;
-		vmassert(intr_disabled());
 	}
 	if(u) { unlock; }
 }
 
-PRIVATE void set_cr3()
-{
-	write_cr3(vm_cr3);
-}
-
 char *cr0_str(u32_t e)
 {
 	static char str[80];
diff --git a/kernel/arch/i386/mpx386.s b/kernel/arch/i386/mpx386.s
index 742891545..ccebabfd6 100755
--- a/kernel/arch/i386/mpx386.s
+++ b/kernel/arch/i386/mpx386.s
@@ -585,8 +585,12 @@ _reload_cr3:
 !*				level0_call				     *
 !*===========================================================================*
 _level0_call:
+! which level0 function to call was passed here by putting it in eax, so
+! we get that from the saved state.
 	call	save
-	jmp	(_level0_func)
+	mov	eax, (_proc_ptr)
+	mov	eax, AXREG(eax)
+	jmp	eax
 
 !*===========================================================================*
 !*				data					     *
diff --git a/kernel/arch/i386/proto.h b/kernel/arch/i386/proto.h
index 5ab71ea57..dccb92256 100644
--- a/kernel/arch/i386/proto.h
+++ b/kernel/arch/i386/proto.h
@@ -76,7 +76,6 @@ _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)  );
 _PROTOTYPE( void phys_outsb, (U16_t port, phys_bytes buf, size_t count) );
 _PROTOTYPE( void phys_outsw, (U16_t port, phys_bytes buf, size_t count) );
-_PROTOTYPE( void i386_invlpg_level0, (void) );
 _PROTOTYPE( int _memcpy_k, (void *dst, void *src, size_t n) );
 _PROTOTYPE( int _memcpy_k_fault, (void) );
 _PROTOTYPE( u32_t read_cr3, (void) );
diff --git a/kernel/glo.h b/kernel/glo.h
index 7c340560c..b6f289392 100755
--- a/kernel/glo.h
+++ b/kernel/glo.h
@@ -78,6 +78,4 @@ extern struct boot_image image[]; 	/* system image processes */
 extern char *t_stack[];			/* task stack space */
 extern struct segdesc_s gdt[];		/* global descriptor table */
 
-EXTERN _PROTOTYPE( void (*level0_func), (void) );
-
 #endif /* GLO_H */