On i386, agp_map_subregion might sleep, which is not allowed in some of

the inteldrm code.  Fix this by adding new interfaces that can map a single
page without sleeping and use that in the execbuffer fast path that needs
this "atomic" behaviour.  Should fix the panic I've seen under memory pressure
on i386.

4 files changed, 70 insertions, 55 deletions

diff --git a/sys/arch/amd64/pci/agp_machdep.c b/sys/arch/amd64/pci/agp_machdep.c
index 669b56d15f8..a09549469a4 100644
--- a/sys/arch/amd64/pci/agp_machdep.c
+++ b/sys/arch/amd64/pci/agp_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: agp_machdep.c,v 1.12 2014/07/12 18:44:41 tedu Exp $	*/
+/*	$OpenBSD: agp_machdep.c,v 1.13 2014/09/20 16:15:16 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2008 - 2009 Owain G. Ainsworth <oga@openbsd.org>
@@ -90,7 +90,7 @@ agp_init_map(bus_space_tag_t tag, bus_addr_t address, bus_size_t size,
 	map->size = size;
 	
 	if ((err = bus_space_map(tag, address, size, flags, &map->bsh)) != 0) {
-		free(map, M_AGP, 0);
+		free(map, M_AGP, sizeof(*map));
 		return (err);
 	}
 	*mapp = map;
@@ -101,7 +101,7 @@ void
 agp_destroy_map(struct agp_map *map)
 {
 	bus_space_unmap(map->bst, map->bsh, map->size);
-	free(map, M_AGP, 0);
+	free(map, M_AGP, sizeof(*map));
 }
 
 
@@ -109,10 +109,7 @@ int
 agp_map_subregion(struct agp_map *map, bus_size_t offset, bus_size_t size,
     bus_space_handle_t *bshp)
 {
-	if (offset > map->size || size > map->size || offset + size > map->size)
-		return (EINVAL);
 	return (bus_space_subregion(map->bst, map->bsh, offset, size, bshp));
-	
 }
 
 void
@@ -121,3 +118,16 @@ agp_unmap_subregion(struct agp_map *map, bus_space_handle_t bsh,
 {
 	/* subregion doesn't need unmapping, do nothing */
 }
+
+void
+agp_map_atomic(struct agp_map *map, bus_size_t offset,
+    bus_space_handle_t *bshp)
+{
+	agp_map_subregion(map, offset, PAGE_SIZE, bshp);
+}
+
+void
+agp_unmap_atomic(struct agp_map *map, bus_space_handle_t bsh)
+{
+	/* subregion doesn't need unmapping, do nothing */
+}
diff --git a/sys/arch/i386/pci/agp_machdep.c b/sys/arch/i386/pci/agp_machdep.c
index 5af66c3131a..c4e4ec37988 100644
--- a/sys/arch/i386/pci/agp_machdep.c
+++ b/sys/arch/i386/pci/agp_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: agp_machdep.c,v 1.18 2014/07/12 18:44:42 tedu Exp $	*/
+/*	$OpenBSD: agp_machdep.c,v 1.19 2014/09/20 16:15:16 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2008 - 2009 Owain G. Ainsworth <oga@openbsd.org>
@@ -74,38 +74,25 @@ struct agp_map {
 	bus_addr_t	addr;
 	bus_size_t	size;
 	int		flags;
+	vaddr_t		va;
 };
 
-extern struct extent	*ioport_ex;
 extern struct extent	*iomem_ex;
 
 int
 agp_init_map(bus_space_tag_t tag, bus_addr_t address, bus_size_t size,
     int flags, struct agp_map **mapp)
 {
-	struct extent	*ex;
-	struct agp_map	*map;
-	int		 error;
-
-	switch (tag) {
-	case I386_BUS_SPACE_IO:
-		ex = ioport_ex;
-		if (flags & BUS_SPACE_MAP_LINEAR)
-			return (EINVAL);
-		break;
-
-	case I386_BUS_SPACE_MEM:
-		ex = iomem_ex;
-		break;
-
-	default:
-		panic("agp_init_map: bad bus space tag");
-	}
+	struct agp_map *map;
+	int error;
+
+	KASSERT(tag == I386_BUS_SPACE_MEM);
+
 	/*
 	 * We grab the extent out of the bus region ourselves
 	 * so we don't need to do these allocations every time.
 	 */
-	error = extent_alloc_region(ex, address, size,
+	error = extent_alloc_region(iomem_ex, address, size,
 	    EX_NOWAIT | EX_MALLOCOK);
 	if (error)
 		return (error);
@@ -119,6 +106,12 @@ agp_init_map(bus_space_tag_t tag, bus_addr_t address, bus_size_t size,
 	map->size = size;
 	map->flags = flags;
 
+	map->va = (vaddr_t)km_alloc(PAGE_SIZE, &kv_any, &kp_none, &kd_waitok);
+	if (map->va == 0) {
+		free(map, M_AGP, sizeof(*map));
+		return (ENOMEM);
+	}
+
 	*mapp = map;
 	return (0);
 }
@@ -126,25 +119,11 @@ agp_init_map(bus_space_tag_t tag, bus_addr_t address, bus_size_t size,
 void
 agp_destroy_map(struct agp_map *map)
 {
-	struct extent	*ex;
-
-	switch (map->bst) {
-	case I386_BUS_SPACE_IO:
-		ex = ioport_ex;
-		break;
-
-	case I386_BUS_SPACE_MEM:
-		ex = iomem_ex;
-		break;
-
-	default:
-		panic("agp_destroy_map: bad bus space tag");
-	}
-
-	if (extent_free(ex, map->addr, map->size,
+	if (extent_free(iomem_ex, map->addr, map->size,
 	    EX_NOWAIT | EX_MALLOCOK ))
-		printf("agp_destroy_map: can't free region\n");
-	free(map, M_AGP, 0);
+		printf("%s: can't free region\n",__func__);
+	km_free((void *)map->va, PAGE_SIZE, &kv_any, &kp_none);
+	free(map, M_AGP, sizeof(*map));
 }
 
 
@@ -162,3 +141,33 @@ agp_unmap_subregion(struct agp_map *map, bus_space_handle_t bsh,
 {
 	return (_bus_space_unmap(map->bst, bsh, size, NULL));
 }
+
+void
+agp_map_atomic(struct agp_map *map, bus_size_t offset,
+    bus_space_handle_t *bshp)
+{
+	int pmap_flags = PMAP_NOCACHE;
+	paddr_t pa;
+
+	KASSERT((offset & PGOFSET) == 0);
+
+	if (map->flags & BUS_SPACE_MAP_CACHEABLE)
+		pmap_flags = 0;
+	else if (map->flags & BUS_SPACE_MAP_PREFETCHABLE)
+		pmap_flags = PMAP_WC;
+
+	pa = bus_space_mmap(map->bst, map->addr, offset, 0, 0);
+	pmap_kenter_pa(map->va, pa | pmap_flags, VM_PROT_READ | VM_PROT_WRITE);
+	pmap_update(pmap_kernel());
+
+	*bshp = (bus_space_handle_t)map->va;
+}
+
+void
+agp_unmap_atomic(struct agp_map *map, bus_space_handle_t bsh)
+{
+	KASSERT(bsh == (bus_space_handle_t)map->va);
+
+	pmap_kremove(map->va, PAGE_SIZE);
+	pmap_update(pmap_kernel());
+}
diff --git a/sys/dev/pci/agpvar.h b/sys/dev/pci/agpvar.h
index 1ac56b5c38c..3101875327a 100644
--- a/sys/dev/pci/agpvar.h
+++ b/sys/dev/pci/agpvar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: agpvar.h,v 1.30 2014/03/26 14:41:41 mpi Exp $	*/
+/*	$OpenBSD: agpvar.h,v 1.31 2014/09/20 16:15:16 kettenis Exp $	*/
 /*	$NetBSD: agpvar.h,v 1.4 2001/10/01 21:54:48 fvdl Exp $	*/
 
 /*-
@@ -177,6 +177,8 @@ int	agp_map_subregion(struct agp_map *, bus_size_t, bus_size_t,
 	    bus_space_handle_t *);
 void	agp_unmap_subregion(struct agp_map *, bus_space_handle_t,
 	    bus_size_t);
+void	agp_map_atomic(struct agp_map *, bus_size_t, bus_space_handle_t *);
+void	agp_unmap_atomic(struct agp_map *, bus_space_handle_t);
 
 int	agp_alloc_dmamem(bus_dma_tag_t, size_t, bus_dmamap_t *,
 	    bus_addr_t *, bus_dma_segment_t *);
diff --git a/sys/dev/pci/drm/i915/i915_gem_execbuffer.c b/sys/dev/pci/drm/i915/i915_gem_execbuffer.c
index a3ef3dc6a0f..279596dca0a 100644
--- a/sys/dev/pci/drm/i915/i915_gem_execbuffer.c
+++ b/sys/dev/pci/drm/i915/i915_gem_execbuffer.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: i915_gem_execbuffer.c,v 1.29 2014/07/12 18:48:52 tedu Exp $	*/
+/*	$OpenBSD: i915_gem_execbuffer.c,v 1.30 2014/09/20 16:15:16 kettenis Exp $	*/
 /*
  * Copyright (c) 2008-2009 Owain G. Ainsworth <oga@openbsd.org>
  *
@@ -233,16 +233,10 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
 
 		/* Map the page containing the relocation we're going to perform.  */
 		reloc->offset += obj->gtt_offset;
-		if ((ret = agp_map_subregion(dev_priv->agph,
-		    trunc_page(reloc->offset), PAGE_SIZE, &bsh)) != 0) {
-			DRM_ERROR("map failed...\n");
-			return -ret;
-		}
-
+		agp_map_atomic(dev_priv->agph, trunc_page(reloc->offset), &bsh);
 		bus_space_write_4(dev_priv->bst, bsh, reloc->offset & PAGE_MASK,	
 		    reloc->delta);
-
-		agp_unmap_subregion(dev_priv->agph, bsh, PAGE_SIZE);
+		agp_unmap_atomic(dev_priv->agph, bsh);
 	}
 
 	/* and update the user's relocation entry */