kernel: vm: Add initial demand paging support

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 43 insertions, 0 deletions

diff --git a/sys/include/vm/fault.h b/sys/include/vm/fault.h
new file mode 100644
index 0000000..f0e308c
--- /dev/null
+++ b/sys/include/vm/fault.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _VM_FAULT_H_
+#define _VM_FAULT_H_
+
+#include <sys/types.h>
+#include <vm/pmap.h>
+
+int vm_fault(vaddr_t va, vm_prot_t access_type);
+
+#endif  /* !_VM_FAULT_H_ */
diff --git a/sys/include/vm/map.h b/sys/include/vm/map.h
index f482788..1da8240 100644
--- a/sys/include/vm/map.h
+++ b/sys/include/vm/map.h
@@ -46,10 +46,14 @@
 /* Memory map table entry count */
 #define MTAB_ENTRIES 32
 
+struct vm_object;
+
 struct vm_mapping {
     TAILQ_ENTRY(vm_mapping) link;
     struct vm_range range;
+    struct vm_object *vmobj;
     paddr_t physmem_base;
+    vm_prot_t prot;
 
     /* Private */
     size_t vhash;           /* Virtual address hash */
diff --git a/sys/include/vm/obj.h b/sys/include/vm/obj.h
index c1c2f17..ef07a1e 100644
--- a/sys/include/vm/obj.h
+++ b/sys/include/vm/obj.h
@@ -42,6 +42,7 @@ struct vm_object {
     struct vm_pagerops *pgops;      /* Pager operations */
 
     uint8_t is_anon : 1;            /* Is an anonymous mapping */
+    uint8_t demand  : 1;            /* Only mapped upon access */
     int ref;                        /* Ref count */
     struct vnode *vnode;            /* Only used if `is_anon` is 0 */
 };