From 660e15b2d125d7c54c2e2ba7da692c47e3fe88bf Mon Sep 17 00:00:00 2001
From: Ben Gras <ben@minix3.org>
Date: Sat, 7 Apr 2012 01:19:28 +0200
Subject: [PATCH] vm: break: allow brk() on any region

use the user-supplied point to lookup which region to perform brk() on,
and if it's a reasonable one, do it, no matter what vm's notion of the
heap region is.
---
 servers/vm/break.c  | 20 ++++++--------------
 servers/vm/proto.h  |  1 +
 servers/vm/region.c | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/servers/vm/break.c b/servers/vm/break.c
index 6882bc1ac..bc4a0687a 100644
--- a/servers/vm/break.c
+++ b/servers/vm/break.c
@@ -167,19 +167,11 @@ int real_brk(vmp, v)
 struct vmproc *vmp;
 vir_bytes v;
 {
-	vir_bytes new_sp;
-	vir_clicks new_clicks;
-	int r;
+	if(!(vmp->vm_flags & VMF_HASPT))
+		return OK;
 
-	new_clicks = (vir_clicks) (CLICK_CEIL(v) >> CLICK_SHIFT);
-	if (new_clicks < vmp->vm_arch.vm_seg[D].mem_vir) {
-		printf("VM: real_brk failed because new_clicks too high: %d\n",
-			new_clicks);
-		return(ENOMEM);
-	}
-	new_clicks -= vmp->vm_arch.vm_seg[D].mem_vir;
-	if ((r=get_stack_ptr(vmp->vm_endpoint, &new_sp)) != OK)
-  		panic("couldn't get stack pointer: %d", r);
-	r = adjust(vmp, new_clicks, new_sp);
-	return r;
+	if(map_region_extend_upto_v(vmp, v) == OK)
+		return OK;
+
+	return(ENOMEM);
 }
diff --git a/servers/vm/proto.h b/servers/vm/proto.h
index 0d3ea3f8a..14dd12feb 100644
--- a/servers/vm/proto.h
+++ b/servers/vm/proto.h
@@ -144,6 +144,7 @@ struct vir_region * map_page_region(struct vmproc *vmp, vir_bytes min,
 struct vir_region * map_proc_kernel(struct vmproc *dst);
 int map_region_extend(struct vmproc *vmp, struct vir_region *vr,
 	vir_bytes delta);
+int map_region_extend_upto_v(struct vmproc *vmp, vir_bytes vir);
 int map_region_shrink(struct vir_region *vr, vir_bytes delta);
 int map_unmap_region(struct vmproc *vmp, struct vir_region *vr,
 	vir_bytes len);
diff --git a/servers/vm/region.c b/servers/vm/region.c
index 2a3cabeba..744ad3ee6 100644
--- a/servers/vm/region.c
+++ b/servers/vm/region.c
@@ -1665,6 +1665,42 @@ struct vir_region *map_proc_kernel(struct vmproc *vmp)
 	return vr; /* Return pointer not useful, just non-NULL. */
 }
 
+int map_region_extend_upto_v(struct vmproc *vmp, vir_bytes v)
+{
+	vir_bytes offset, o, end;
+	struct vir_region *vr, *nextvr;
+
+	offset = arch_vir2map(vmp, v);
+
+	if((o=(offset % VM_PAGE_SIZE))) {
+		offset+= VM_PAGE_SIZE - o;
+	}
+
+	if(!(vr = region_search(&vmp->vm_regions_avl, offset, AVL_LESS_EQUAL))) {
+		printf("VM: nothing to extend\n");
+		return ENOMEM;
+	}
+
+	if(!(vr->flags & VR_ANON)) {
+		printf("VM: memory range to extend not anonymous\n");
+		return ENOMEM;
+	}
+
+	assert(vr->vaddr <= offset);
+	if((nextvr = getnextvr(vr))) {
+		assert(offset < nextvr->vaddr);
+	}
+
+	end = vr->vaddr + vr->length;
+
+	if(offset < end)
+		return map_region_shrink(vr, end - offset);
+
+	return map_region_extend(vmp, vr, offset - end);
+
+	return ENOMEM;
+}
+
 /*========================================================================*
  *				map_region_extend	     	  	*
  *========================================================================*/