On sgi, use CKSEG0 addresses whenever possible for pmap_map_direct and u area

pages. This will allow R5000-based systems with physical memory fitting in
CKSEG0 to use 16KB pages and direct maps (since only XKPHYS accesses trigger
the XKPHYS coherency errata on these processors).
Tested on IP32, IP30 and IP27 (and loongson too as well).

2 files changed, 42 insertions, 13 deletions

diff --git a/sys/arch/mips64/mips64/pmap.c b/sys/arch/mips64/mips64/pmap.c
index d3edd57e995..96ebbbe9358 100644
--- a/sys/arch/mips64/mips64/pmap.c
+++ b/sys/arch/mips64/mips64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.55 2012/03/19 20:42:26 miod Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.56 2012/03/19 21:56:49 miod Exp $	*/
 
 /*
  * Copyright (c) 2001-2004 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -140,7 +140,6 @@ static struct pmap	kernel_pmap_store
 		/ sizeof(struct pmap)];
 struct pmap *const kernel_pmap_ptr = kernel_pmap_store;
 
-psize_t	mem_size;	/* memory size in bytes */
 vaddr_t	virtual_start;  /* VA of first avail page (after kernel bss)*/
 vaddr_t	virtual_end;	/* VA of last avail page (end of kernel AS) */
 
@@ -437,16 +436,14 @@ pmap_steal_memory(vsize_t size, vaddr_t *vstartp, vaddr_t *vendp)
 
 #ifdef __sgi__
 		/*
-		 * If we are running with a 32 bit ARCBios (i.e. kernel
-		 * linked in CKSEG0), return a CKSEG0 address whenever possible.
+		 * Return a CKSEG0 address whenever possible.
 		 */
-		if (IS_XKPHYS((vaddr_t)&pmap_steal_memory) ||
-		    pa + size >= CKSEG_SIZE)
-			va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
-		else
+		if (pa + size < CKSEG_SIZE)
 			va = PHYS_TO_CKSEG0(pa);
-#else
+		else
 			va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
+#else
+		va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
 #endif
 
 		bzero((void *)va, size);
@@ -1651,7 +1648,19 @@ vaddr_t
 pmap_map_direct(vm_page_t pg)
 {
 	paddr_t pa = VM_PAGE_TO_PHYS(pg);
-	vaddr_t va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
+	vaddr_t va;
+
+#ifdef __sgi__
+	/*
+	 * Return a CKSEG0 address whenever possible.
+	 */
+	if (pa < CKSEG_SIZE)
+		va = PHYS_TO_CKSEG0(pa);
+	else
+		va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
+#else
+	va = PHYS_TO_XKPHYS(pa, CCA_CACHED);
+#endif
 
 	return va;
 }
@@ -1659,9 +1668,19 @@ pmap_map_direct(vm_page_t pg)
 vm_page_t
 pmap_unmap_direct(vaddr_t va)
 {
-	paddr_t pa = XKPHYS_TO_PHYS(va);
-	vm_page_t pg = PHYS_TO_VM_PAGE(pa);
+	paddr_t pa;
+	vm_page_t pg;
 
+#ifdef __sgi__
+	if (va >= CKSEG0_BASE)
+		pa = CKSEG0_TO_PHYS(va);
+	else
+		pa = XKPHYS_TO_PHYS(va);
+#else
+	pa = XKPHYS_TO_PHYS(va);
+#endif
+
+	pg = PHYS_TO_VM_PAGE(pa);
 	if (CpuCacheAliasMask)
 		Mips_HitInvalidateDCache(curcpu(), va, pa, PAGE_SIZE);
 
diff --git a/sys/arch/mips64/mips64/vm_machdep.c b/sys/arch/mips64/mips64/vm_machdep.c
index 7ed194dea94..ff823b6aea9 100644
--- a/sys/arch/mips64/mips64/vm_machdep.c
+++ b/sys/arch/mips64/mips64/vm_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm_machdep.c,v 1.24 2010/11/24 21:16:28 miod Exp $	*/
+/*	$OpenBSD: vm_machdep.c,v 1.25 2012/03/19 21:56:49 miod Exp $	*/
 /*
  * Copyright (c) 1988 University of Utah.
  * Copyright (c) 1992, 1993
@@ -76,8 +76,18 @@ cpu_fork(p1, p2, stack, stacksize, func, arg)
 	/* replace p_addr with a direct translation address */
 	p2->p_md.md_uarea = (vaddr_t)p2->p_addr;
 	pmap_extract(pmap_kernel(), p2->p_md.md_uarea, &pa);
+#ifdef __sgi__
+	/*
+	 * Return a CKSEG0 address whenever possible.
+	 */
+	if (pa < CKSEG_SIZE)
+		p2->p_addr = (void *)PHYS_TO_CKSEG0(pa);
+	else
+		p2->p_addr = (void *)PHYS_TO_XKPHYS(pa, CCA_CACHED);
+#else
 	p2->p_addr = (void *)PHYS_TO_XKPHYS(pa, CCA_CACHED);
 #endif
+#endif
 	pcb = &p2->p_addr->u_pcb;
 
 	/*