Lots of stuff.

[polintos/scott/priv.git] / kernel / include / kern / rmap.h

diff --git a/kernel/include/kern/rmap.h b/kernel/include/kern/rmap.h
new file mode 100644 (file)
index 0000000..86dacd6
--- /dev/null
+++ b/kernel/include/kern/rmap.h
@@ -0,0 +1,52 @@
+#ifndef _KERN_RMAP_H
+#define _KERN_RMAP_H
+
+#include <kern/mem.h>
+#include <kern/radix.h>
+
+namespace Mem {
+       struct RMapNode {
+               u64 vaddr;
+               VirtualArea *va;
+               Util::ListNoAutoInit head, tail;
+       };
+
+       namespace RMap {
+               enum {
+                       head_offset = offsetof(RMapNode, head),
+                       tail_offset = offsetof(RMapNode, tail),
+               };
+       }
+       
+       // This lock protects the rmap chains and rmap tables.  It also makes
+       // atomic the PageTable::get_mapping, RMapTable::map, PageTable::map
+       // sequence.
+       //
+       // OPT: This lock is acquired on all map/unmap activity; if/when this
+       // turns out to be a significant bottleneck, finer-grained locking can
+       // be used.  I decided against doing it now because it would be
+       // somewhat complicated (but I believe do-able) to avoid all races,
+       // and I'd like to move on to implementing other things for now.
+       
+       extern Lock::Lock rmap_lock;
+       class Page;
+       
+       class RMapTable {
+               Util::RadixTree<RMapNode, u64> tree;
+               
+       public:
+               // rmap_lock must be held.
+               static void map(VirtualArea *downstream_va, PageTable *upstream_ptbl,
+                               u64 virtaddr, u64 upstream_vaddr);
+
+               void unmap(u64 virtaddr);
+
+               // Handle a copy-on-write for the specified page and all downstream
+               // mappings.  All such mappings are set to the new page, and
+               // FaultOnWrite is cleared.
+               
+               void break_copy_on_write(u64 virtaddr, Page *new_page);
+       };
+};
+
+#endif