From 6d52d019d4e31696ee082ee4cd82b1b7fe045c35 Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Fri, 23 Jan 2015 17:09:23 +0000
Subject: [PATCH] Make km_alloc(9) use the direct map for all "phys contig"
 mappings requested by the caller on architectures that implement them.  Make
 sure that we physically align memory such that we meet any demands on virtual
 alignment in this case.  This should reduce the overhead of mapping large
 pool pages for pools that request dma'able memory.

ok deraadt@, dlg@
---
 sys/uvm/uvm_km.c | 66 +++++++++++++++++++++---------------------------
 1 file changed, 29 insertions(+), 37 deletions(-)

diff --git a/sys/uvm/uvm_km.c b/sys/uvm/uvm_km.c
index 6266c8d9c37..899dbf591a0 100644
--- a/sys/uvm/uvm_km.c
+++ b/sys/uvm/uvm_km.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.c,v 1.123 2014/12/17 06:58:11 guenther Exp $	*/
+/*	$OpenBSD: uvm_km.c,v 1.124 2015/01/23 17:09:23 kettenis Exp $	*/
 /*	$NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $	*/
 
 /* 
@@ -809,11 +809,9 @@ km_alloc(size_t sz, const struct kmem_va_mode *kv,
 	struct pglist pgl;
 	int mapflags = 0;
 	vm_prot_t prot;
+	paddr_t pla_align;
 	int pla_flags;
 	int pla_maxseg;
-#ifdef __HAVE_PMAP_DIRECT
-	paddr_t pa;
-#endif
 	vaddr_t va, sva;
 
 	KASSERT(sz == round_page(sz));
@@ -828,46 +826,33 @@ km_alloc(size_t sz, const struct kmem_va_mode *kv,
 	if (kp->kp_zero)
 		pla_flags |= UVM_PLA_ZERO;
 
+	pla_align = kp->kp_align;
+#ifdef __HAVE_PMAP_DIRECT
+	if (pla_align < kv->kv_align)
+		pla_align = kv->kv_align;
+#endif
 	pla_maxseg = kp->kp_maxseg;
 	if (pla_maxseg == 0)
 		pla_maxseg = sz / PAGE_SIZE;
 
 	if (uvm_pglistalloc(sz, kp->kp_constraint->ucr_low,
-	    kp->kp_constraint->ucr_high, kp->kp_align, kp->kp_boundary,
+	    kp->kp_constraint->ucr_high, pla_align, kp->kp_boundary,
 	    &pgl, pla_maxseg, pla_flags)) {	
 		return (NULL);
 	}
 
 #ifdef __HAVE_PMAP_DIRECT
-	if (kv->kv_align)
-		goto alloc_va;
-#if 1
 	/*
-	 * For now, only do DIRECT mappings for single page
-	 * allocations, until we figure out a good way to deal
-	 * with contig allocations in km_free.
+	 * Only use direct mappings for single page or single segment
+	 * allocations.
 	 */
-	if (!kv->kv_singlepage)
-		goto alloc_va;
-#endif
-	/*
-	 * Dubious optimization. If we got a contig segment, just map it
-	 * through the direct map.
-	 */
-	TAILQ_FOREACH(pg, &pgl, pageq) {
-		if (pg != TAILQ_FIRST(&pgl) &&
-		    VM_PAGE_TO_PHYS(pg) != pa + PAGE_SIZE)
-			break;
-		pa = VM_PAGE_TO_PHYS(pg);
-	}
-	if (pg == NULL) {
+	if (kv->kv_singlepage || kp->kp_maxseg == 1) {
 		TAILQ_FOREACH(pg, &pgl, pageq) {
-			vaddr_t v;
-			v = pmap_map_direct(pg);
+			va = pmap_map_direct(pg);
 			if (pg == TAILQ_FIRST(&pgl))
-				va = v;
+				sva = va;
 		}
-		return ((void *)va);
+		return ((void *)sva);
 	}
 #endif
 alloc_va:
@@ -947,28 +932,35 @@ km_free(void *v, size_t sz, const struct kmem_va_mode *kv,
 	struct vm_page *pg;
 	struct pglist pgl;
 
-	sva = va = (vaddr_t)v;
-	eva = va + sz;
+	sva = (vaddr_t)v;
+	eva = sva + sz;
 
-	if (kp->kp_nomem) {
+	if (kp->kp_nomem)
 		goto free_va;
-	}
 
-	if (kv->kv_singlepage) {
 #ifdef __HAVE_PMAP_DIRECT
-		pg = pmap_unmap_direct(va);
-		uvm_pagefree(pg);
+	if (kv->kv_singlepage || kp->kp_maxseg == 1) {
+		TAILQ_INIT(&pgl);
+		for (va = sva; va < eva; va += PAGE_SIZE) {
+			pg = pmap_unmap_direct(va);
+			TAILQ_INSERT_TAIL(&pgl, pg, pageq);
+		}
+		uvm_pglistfree(&pgl);
+		return;
+	}
 #else
+	if (kv->kv_singlepage) {
 		struct uvm_km_free_page *fp = v;
+
 		mtx_enter(&uvm_km_pages.mtx);
 		fp->next = uvm_km_pages.freelist;
 		uvm_km_pages.freelist = fp;
 		if (uvm_km_pages.freelistlen++ > 16)
 			wakeup(&uvm_km_pages.km_proc);
 		mtx_leave(&uvm_km_pages.mtx);
-#endif
 		return;
 	}
+#endif
 
 	if (kp->kp_pageable) {
 		pmap_remove(pmap_kernel(), sva, eva);
-- 
2.20.1