sh: New extended page flag to wire/unwire TLB entries

Provide a new extended page flag, _PAGE_WIRED and an SH4 implementation
for wiring TLB entries and use it in the fixmap code path so that we can
wire the fixmap TLB entry.

Signed-off-by: Matt Fleming <matt@console-pimps.org>

2 files changed, 20 insertions, 0 deletions

diff --git a/arch/sh/include/asm/pgtable_32.h b/arch/sh/include/asm/pgtable_32.h
index 5003ee86f67b..c573d45f1286 100644
--- a/arch/sh/include/asm/pgtable_32.h
+++ b/arch/sh/include/asm/pgtable_32.h
@@ -71,6 +71,8 @@
 #define _PAGE_EXT_KERN_WRITE    0x1000  /* EPR4-bit: Kernel space writable */
 #define _PAGE_EXT_KERN_READ     0x2000  /* EPR5-bit: Kernel space readable */
 
+#define _PAGE_EXT_WIRED         0x4000  /* software: Wire TLB entry */
+
 /* Wrapper for extended mode pgprot twiddling */
 #define _PAGE_EXT(x)            ((unsigned long long)(x) << 32)
 
@@ -164,6 +166,8 @@ static inline unsigned long copy_ptea_attributes(unsigned long x)
         (PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | \
          _PAGE_DIRTY | _PAGE_SPECIAL)
 
+#define _PAGE_WIRED     (_PAGE_EXT(_PAGE_EXT_WIRED))
+
 #ifndef __ASSEMBLY__
 
 #if defined(CONFIG_X2TLB) /* SH-X2 TLB */
diff --git a/arch/sh/include/asm/tlb.h b/arch/sh/include/asm/tlb.h
index da8fe7ab8728..3ed2f7a05416 100644
--- a/arch/sh/include/asm/tlb.h
+++ b/arch/sh/include/asm/tlb.h
@@ -97,6 +97,22 @@ tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 
 #define tlb_migrate_finish(mm)          do { } while (0)
 
+#ifdef CONFIG_CPU_SH4
+extern void tlb_wire_entry(struct vm_area_struct *, unsigned long, pte_t);
+extern void tlb_unwire_entry(void);
+#else
+static inline void tlb_wire_entry(struct vm_area_struct *vma ,
+                                  unsigned long addr, pte_t pte)
+{
+        BUG();
+}
+
+static inline void tlb_unwire_entry(void)
+{
+        BUG();
+}
+#endif /* CONFIG_CPU_SH4 */
+
 #else /* CONFIG_MMU */
 
 #define tlb_start_vma(tlb, vma)                         do { } while (0)