x86, pat: Migrate to rbtree only backend for pat memtype management

Move pat backend to fully rbtree based implementation from the existing
rbtree and linked list hybrid.

New rbtree based solution uses interval trees (augmented rbtrees) in
order to store the PAT ranges. The new code seprates out the pat backend
to pat_rbtree.c file, making is cleaner. The change also makes the PAT
lookup, reserve and free operations more optimal, as we don't have to
traverse linear linked list of few tens of entries in normal case.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <20100210232607.GB11465@linux-os.sc.intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/arch/x86/mm/pat_internal.h b/arch/x86/mm/pat_internal.h
index 6c98780eb731..4f39eefa3e61 100644
--- a/arch/x86/mm/pat_internal.h
+++ b/arch/x86/mm/pat_internal.h
@@ -9,8 +9,8 @@ extern int pat_debug_enable;
 struct memtype {
         u64                     start;
         u64                     end;
+        u64                     subtree_max_end;
         unsigned long           type;
-        struct list_head        nd;
         struct rb_node          rb;
 };
 
@@ -25,4 +25,22 @@ static inline char *cattr_name(unsigned long flags)
         }
 }
 
+#ifdef CONFIG_X86_PAT
+extern int rbt_memtype_check_insert(struct memtype *new,
+                                        unsigned long *new_type);
+extern int rbt_memtype_erase(u64 start, u64 end);
+extern struct memtype *rbt_memtype_lookup(u64 addr);
+extern int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos);
+#else
+static inline int rbt_memtype_check_insert(struct memtype *new,
+                                        unsigned long *new_type)
+{ return 0; }
+static inline int rbt_memtype_erase(u64 start, u64 end)
+{ return 0; }
+static inline struct memtype *rbt_memtype_lookup(u64 addr)
+{ return NULL; }
+static inline int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos)
+{ return 0; }
+#endif
+
 #endif /* __PAT_INTERNAL_H_ */