x86: mm: Move PAT only functions to mm/pat.c

Commit e00c8cc93c1a "x86: Use new cache mode type in memtype related
functions" broke the ARCH=um build.

 arch/x86/include/asm/cacheflush.h:67:36: error: return type is an incomplete type
 static inline enum page_cache_mode get_page_memtype(struct page *pg)

The reason is simple. get_page_memtype() and set_page_memtype()
require enum page_cache_mode now, which is defined in
asm/pgtable_types.h. UM does not include that file for obvious reasons.

The simple solution is to move that functions to arch/x86/mm/pat.c
where the only callsites of this are located. They should have been
there in the first place.

Fixes: e00c8cc93c1a "x86: Use new cache mode type in memtype related functions"
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Richard Weinberger <richard@nod.at>

1 files changed, 69 insertions, 0 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 4c601276a556..25d2c58489e0 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -67,6 +67,75 @@ __setup("debugpat", pat_debug_setup);
 
 static u64 __read_mostly boot_pat_state;
 
+#ifdef CONFIG_X86_PAT
+/*
+ * X86 PAT uses page flags WC and Uncached together to keep track of
+ * memory type of pages that have backing page struct. X86 PAT supports 3
+ * different memory types, _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC and
+ * _PAGE_CACHE_MODE_UC_MINUS and fourth state where page's memory type has not
+ * been changed from its default (value of -1 used to denote this).
+ * Note we do not support _PAGE_CACHE_MODE_UC here.
+ */
+
+#define _PGMT_DEFAULT           0
+#define _PGMT_WC                (1UL << PG_arch_1)
+#define _PGMT_UC_MINUS          (1UL << PG_uncached)
+#define _PGMT_WB                (1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_MASK              (1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_CLEAR_MASK        (~_PGMT_MASK)
+
+static inline enum page_cache_mode get_page_memtype(struct page *pg)
+{
+        unsigned long pg_flags = pg->flags & _PGMT_MASK;
+
+        if (pg_flags == _PGMT_DEFAULT)
+                return -1;
+        else if (pg_flags == _PGMT_WC)
+                return _PAGE_CACHE_MODE_WC;
+        else if (pg_flags == _PGMT_UC_MINUS)
+                return _PAGE_CACHE_MODE_UC_MINUS;
+        else
+                return _PAGE_CACHE_MODE_WB;
+}
+
+static inline void set_page_memtype(struct page *pg,
+                                    enum page_cache_mode memtype)
+{
+        unsigned long memtype_flags;
+        unsigned long old_flags;
+        unsigned long new_flags;
+
+        switch (memtype) {
+        case _PAGE_CACHE_MODE_WC:
+                memtype_flags = _PGMT_WC;
+                break;
+        case _PAGE_CACHE_MODE_UC_MINUS:
+                memtype_flags = _PGMT_UC_MINUS;
+                break;
+        case _PAGE_CACHE_MODE_WB:
+                memtype_flags = _PGMT_WB;
+                break;
+        default:
+                memtype_flags = _PGMT_DEFAULT;
+                break;
+        }
+
+        do {
+                old_flags = pg->flags;
+                new_flags = (old_flags & _PGMT_CLEAR_MASK) | memtype_flags;
+        } while (cmpxchg(&pg->flags, old_flags, new_flags) != old_flags);
+}
+#else
+static inline enum page_cache_mode get_page_memtype(struct page *pg)
+{
+        return -1;
+}
+static inline void set_page_memtype(struct page *pg,
+                                    enum page_cache_mode memtype)
+{
+}
+#endif
+
 enum {
         PAT_UC = 0,             /* uncached */
         PAT_WC = 1,             /* Write combining */