Port the new PV entry allocator from amd64/i386. This allocator has two

advantages.  First, PV entries are roughly half the size.  Second, this
allocator doesn't access the paging queues, and thus it will allow for the
removal of the page queues lock from this pmap.

Fix a rather serious bug in pmap_remove_write().  After removing write
access from the specified page's first mapping, pmap_remove_write() then
used the wrong "next" pointer.  Consequently, the page's second, third,
etc. mappings were not write protected.

Tested by:	jchandra

1 files changed, 21 insertions, 5 deletions

diff --git a/sys/mips/include/pmap.h b/sys/mips/include/pmap.h
index e10212b..e75ccb7 100644
--- a/sys/mips/include/pmap.h
+++ b/sys/mips/include/pmap.h
@@ -66,9 +66,9 @@
  * Pmap stuff
  */
 struct pv_entry;
+struct pv_chunk;
 
 struct md_page {
-	int pv_list_count;
 	int pv_flags;
 	TAILQ_HEAD(, pv_entry) pv_list;
 };
@@ -82,8 +82,7 @@ struct md_page {
 
 struct pmap {
 	pd_entry_t *pm_segtab;	/* KVA of segment table */
-	TAILQ_HEAD(, pv_entry) pm_pvlist;	/* list of mappings in
-						 * pmap */
+	TAILQ_HEAD(, pv_chunk)	pm_pvchunk;	/* list of mappings in pmap */
 	cpuset_t	pm_active;		/* active on cpus */
 	struct {
 		u_int32_t asid:ASID_BITS;	/* TLB address space tag */
@@ -121,13 +120,30 @@ extern struct pmap	kernel_pmap_store;
  * mappings of that page.  An entry is a pv_entry_t, the list is pv_table.
  */
 typedef struct pv_entry {
-	pmap_t pv_pmap;		/* pmap where mapping lies */
 	vm_offset_t pv_va;	/* virtual address for mapping */
 	TAILQ_ENTRY(pv_entry) pv_list;
-	TAILQ_ENTRY(pv_entry) pv_plist;
 }       *pv_entry_t;
 
 /*
+ * pv_entries are allocated in chunks per-process.  This avoids the
+ * need to track per-pmap assignments.
+ */
+#ifdef __mips_n64
+#define	_NPCM	3
+#define	_NPCPV	168
+#else
+#define	_NPCM	11
+#define	_NPCPV	336
+#endif
+struct pv_chunk {
+	pmap_t			pc_pmap;
+	TAILQ_ENTRY(pv_chunk)	pc_list;
+	u_long			pc_map[_NPCM];	/* bitmap; 1 = free */
+	TAILQ_ENTRY(pv_chunk)	pc_lru;
+	struct pv_entry		pc_pventry[_NPCPV];
+};
+
+/*
  * physmem_desc[] is a superset of phys_avail[] and describes all the
  * memory present in the system.
  *