Reimplement the splay tree used for idle page table pages using

md_page iterators. Additively, embed the left and right pointers as an
union with the pv_list as the page table pages don't need reverse
mapping. This way, this code is no longer using the root and left
iterators from the vm_page itself and once the red/black algorithm for
cached pages will be implemented will allow removing completely the
extra two pointers from vm_page.

Implementation notes: it is interesting to note that now
pmap_vmpage_splay() is just a copy&paste of the vm_page_splay(),
but working on the md_page iterators. This is necessary because in the
end the vm_page_splay() will be completely removed.
Also, note that pv_list iterator is renamed in a more "common" way
because of problems with macro expansions.

Outlined, discussed and reviewed by:	jeff

1 files changed, 13 insertions, 3 deletions

diff --git a/sys/amd64/include/pmap.h b/sys/amd64/include/pmap.h
index 1b8108a..eabf1dc 100644
--- a/sys/amd64/include/pmap.h
+++ b/sys/amd64/include/pmap.h
@@ -240,10 +240,20 @@ struct	pv_entry;
 struct	pv_chunk;
 
 struct md_page {
-	TAILQ_HEAD(,pv_entry)	pv_list;
-	int			pat_mode;
+	union {
+		TAILQ_HEAD(,pv_entry)	pvi_list;
+		struct {
+			vm_page_t	pii_left;
+			vm_page_t	pii_right;
+		} pvi_siters;
+	} pv_structs;
+	int				pat_mode;
 };
 
+#define	pv_list		pv_structs.pvi_list
+#define	pv_left		pv_structs.pvi_siters.pii_left
+#define	pv_right	pv_structs.pvi_siters.pii_right
+
 /*
  * The kernel virtual address (KVA) of the level 4 page table page is always
  * within the direct map (DMAP) region.
@@ -282,7 +292,7 @@ extern struct pmap	kernel_pmap_store;
  */
 typedef struct pv_entry {
 	vm_offset_t	pv_va;		/* virtual address for mapping */
-	TAILQ_ENTRY(pv_entry)	pv_list;
+	TAILQ_ENTRY(pv_entry)	pv_next;
 } *pv_entry_t;
 
 /*