PERFORCE change 133821 for review

[Warner Losh]

http://perforce.freebsd.org/chv.cgi?CH=133821

Change 133821 by imp at imp_lighthouse on 2008/01/21 22:42:30

	Cope with kstack0 being in KSEG0.  I'm not sure this is right,
	but it may be right enough for the moment.  gonzo@ is trying to
	puzzle out if this is good or not.

Affected files ...

.. //depot/projects/mips2-jnpr/src/sys/mips/mips/vm_machdep.c#8 edit

Differences ...

==== //depot/projects/mips2-jnpr/src/sys/mips/mips/vm_machdep.c#8 (text+ko) ====

@@ -140,13 +140,22 @@
 	td2->td_frame->v1 = 1;
 	td2->td_frame->a3 = 0;
 
-	if (!(pte = pmap_segmap(kernel_pmap, (vm_offset_t)td2->td_kstack)))
-		panic("cpu_fork: invalid segmap");
-	pte += ((vm_offset_t)td2->td_kstack >> PGSHIFT) & (NPTEPG - 1);
-
-	for (i = 0; i < KSTACK_PAGES; i++) {
-		td2->td_md.md_upte[i] = *pte & ~(PG_RO|PG_WIRED);
-		pte++;
+	/*
+	 * thread 0 has its stack in KSEG0 space.  In that case, there's
+	 * nothing to do since we're not going to change the physical address
+	 * of where we're swapped in at...
+	 */
+	pte = pmap_segmap(kernel_pmap, (vm_offset_t)td2->td_kstack;
+	if (pte == NULL) {
+		if ((vm_offset_t)td->td_kstack < MIPS_KSEG0_START &&
+		    (vm_offset_t)td->td_kstack > MIPS_KSEG0_END)
+			panic("cpu_fork: invalid segmap");
+	} else {
+		pte += ((vm_offset_t)td2->td_kstack >> PGSHIFT) & (NPTEPG - 1);
+		for (i = 0; i < KSTACK_PAGES; i++) {
+			td2->td_md.md_upte[i] = *pte & ~(PG_RO|PG_WIRED);
+			pte++;
+		}
 	}
 
 	if (td1 == PCPU_GET(fpcurthread))
@@ -249,6 +258,15 @@
 	    td->td_kstack_pages * PAGE_SIZE) - 1;
 	td->td_frame = &td->td_pcb->pcb_regs;
 
+	/*
+	 * thread 0 has its stack in KSEG0 space.  In that case, there's
+	 * nothing to do since we're not going to change the physical address
+	 * of where we're swapped in at...
+	 */
+	if ((vm_offset_t)td->td_kstack > MIPS_KSEG0_START &&
+	    (vm_offset_t)td->td_kstack < MIPS_KSEG0_END)
+		return;
+	
 	if (!(pte = pmap_segmap(kernel_pmap, (vm_offset_t)td->td_kstack)))
 		panic("cpu_thread_alloc: invalid segmap");
 	pte += ((vm_offset_t)td->td_kstack >> PGSHIFT) & (NPTEPG - 1);