sh: Split out pgtable.h in to _32 and _64 variants.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 473 insertions, 0 deletions

diff --git a/include/asm-sh/pgtable_32.h b/include/asm-sh/pgtable_32.h
new file mode 100644
index 000000000000..70303603e89d
--- /dev/null
+++ b/include/asm-sh/pgtable_32.h
@@ -0,0 +1,473 @@
+#ifndef __ASM_SH_PGTABLE_32_H
+#define __ASM_SH_PGTABLE_32_H
+
+/*
+ * Linux PTEL encoding.
+ *
+ * Hardware and software bit definitions for the PTEL value (see below for
+ * notes on SH-X2 MMUs and 64-bit PTEs):
+ *
+ * - Bits 0 and 7 are reserved on SH-3 (_PAGE_WT and _PAGE_SZ1 on SH-4).
+ *
+ * - Bit 1 is the SH-bit, but is unused on SH-3 due to an MMU bug (the
+ *   hardware PTEL value can't have the SH-bit set when MMUCR.IX is set,
+ *   which is the default in cpu-sh3/mmu_context.h:MMU_CONTROL_INIT).
+ *
+ *   In order to keep this relatively clean, do not use these for defining
+ *   SH-3 specific flags until all of the other unused bits have been
+ *   exhausted.
+ *
+ * - Bit 9 is reserved by everyone and used by _PAGE_PROTNONE.
+ *
+ * - Bits 10 and 11 are low bits of the PPN that are reserved on >= 4K pages.
+ *   Bit 10 is used for _PAGE_ACCESSED, bit 11 remains unused.
+ *
+ * - Bits 31, 30, and 29 remain unused by everyone and can be used for future
+ *   software flags, although care must be taken to update _PAGE_CLEAR_FLAGS.
+ *
+ * XXX: Leave the _PAGE_FILE and _PAGE_WT overhaul for a rainy day.
+ *
+ * SH-X2 MMUs and extended PTEs
+ *
+ * SH-X2 supports an extended mode TLB with split data arrays due to the
+ * number of bits needed for PR and SZ (now EPR and ESZ) encodings. The PR and
+ * SZ bit placeholders still exist in data array 1, but are implemented as
+ * reserved bits, with the real logic existing in data array 2.
+ *
+ * The downside to this is that we can no longer fit everything in to a 32-bit
+ * PTE encoding, so a 64-bit pte_t is necessary for these parts. On the plus
+ * side, this gives us quite a few spare bits to play with for future usage.
+ */
+/* Legacy and compat mode bits */
+#define _PAGE_WT        0x001           /* WT-bit on SH-4, 0 on SH-3 */
+#define _PAGE_HW_SHARED 0x002           /* SH-bit  : shared among processes */
+#define _PAGE_DIRTY     0x004           /* D-bit   : page changed */
+#define _PAGE_CACHABLE  0x008           /* C-bit   : cachable */
+#define _PAGE_SZ0       0x010           /* SZ0-bit : Size of page */
+#define _PAGE_RW        0x020           /* PR0-bit : write access allowed */
+#define _PAGE_USER      0x040           /* PR1-bit : user space access allowed*/
+#define _PAGE_SZ1       0x080           /* SZ1-bit : Size of page (on SH-4) */
+#define _PAGE_PRESENT   0x100           /* V-bit   : page is valid */
+#define _PAGE_PROTNONE  0x200           /* software: if not present  */
+#define _PAGE_ACCESSED  0x400           /* software: page referenced */
+#define _PAGE_FILE      _PAGE_WT        /* software: pagecache or swap? */
+
+#define _PAGE_SZ_MASK   (_PAGE_SZ0 | _PAGE_SZ1)
+#define _PAGE_PR_MASK   (_PAGE_RW | _PAGE_USER)
+
+/* Extended mode bits */
+#define _PAGE_EXT_ESZ0          0x0010  /* ESZ0-bit: Size of page */
+#define _PAGE_EXT_ESZ1          0x0020  /* ESZ1-bit: Size of page */
+#define _PAGE_EXT_ESZ2          0x0040  /* ESZ2-bit: Size of page */
+#define _PAGE_EXT_ESZ3          0x0080  /* ESZ3-bit: Size of page */
+
+#define _PAGE_EXT_USER_EXEC     0x0100  /* EPR0-bit: User space executable */
+#define _PAGE_EXT_USER_WRITE    0x0200  /* EPR1-bit: User space writable */
+#define _PAGE_EXT_USER_READ     0x0400  /* EPR2-bit: User space readable */
+
+#define _PAGE_EXT_KERN_EXEC     0x0800  /* EPR3-bit: Kernel space executable */
+#define _PAGE_EXT_KERN_WRITE    0x1000  /* EPR4-bit: Kernel space writable */
+#define _PAGE_EXT_KERN_READ     0x2000  /* EPR5-bit: Kernel space readable */
+
+/* Wrapper for extended mode pgprot twiddling */
+#define _PAGE_EXT(x)            ((unsigned long long)(x) << 32)
+
+/* software: moves to PTEA.TC (Timing Control) */
+#define _PAGE_PCC_AREA5 0x00000000      /* use BSC registers for area5 */
+#define _PAGE_PCC_AREA6 0x80000000      /* use BSC registers for area6 */
+
+/* software: moves to PTEA.SA[2:0] (Space Attributes) */
+#define _PAGE_PCC_IODYN 0x00000001      /* IO space, dynamically sized bus */
+#define _PAGE_PCC_IO8   0x20000000      /* IO space, 8 bit bus */
+#define _PAGE_PCC_IO16  0x20000001      /* IO space, 16 bit bus */
+#define _PAGE_PCC_COM8  0x40000000      /* Common Memory space, 8 bit bus */
+#define _PAGE_PCC_COM16 0x40000001      /* Common Memory space, 16 bit bus */
+#define _PAGE_PCC_ATR8  0x60000000      /* Attribute Memory space, 8 bit bus */
+#define _PAGE_PCC_ATR16 0x60000001      /* Attribute Memory space, 6 bit bus */
+
+/* Mask which drops unused bits from the PTEL value */
+#if defined(CONFIG_CPU_SH3)
+#define _PAGE_CLEAR_FLAGS       (_PAGE_PROTNONE | _PAGE_ACCESSED| \
+                                 _PAGE_FILE     | _PAGE_SZ1     | \
+                                 _PAGE_HW_SHARED)
+#elif defined(CONFIG_X2TLB)
+/* Get rid of the legacy PR/SZ bits when using extended mode */
+#define _PAGE_CLEAR_FLAGS       (_PAGE_PROTNONE | _PAGE_ACCESSED | \
+                                 _PAGE_FILE | _PAGE_PR_MASK | _PAGE_SZ_MASK)
+#else
+#define _PAGE_CLEAR_FLAGS       (_PAGE_PROTNONE | _PAGE_ACCESSED | _PAGE_FILE)
+#endif
+
+#define _PAGE_FLAGS_HARDWARE_MASK       (0x1fffffff & ~(_PAGE_CLEAR_FLAGS))
+
+/* Hardware flags, page size encoding */
+#if defined(CONFIG_X2TLB)
+# if defined(CONFIG_PAGE_SIZE_4KB)
+#  define _PAGE_FLAGS_HARD      _PAGE_EXT(_PAGE_EXT_ESZ0)
+# elif defined(CONFIG_PAGE_SIZE_8KB)
+#  define _PAGE_FLAGS_HARD      _PAGE_EXT(_PAGE_EXT_ESZ1)
+# elif defined(CONFIG_PAGE_SIZE_64KB)
+#  define _PAGE_FLAGS_HARD      _PAGE_EXT(_PAGE_EXT_ESZ2)
+# endif
+#else
+# if defined(CONFIG_PAGE_SIZE_4KB)
+#  define _PAGE_FLAGS_HARD      _PAGE_SZ0
+# elif defined(CONFIG_PAGE_SIZE_64KB)
+#  define _PAGE_FLAGS_HARD      _PAGE_SZ1
+# endif
+#endif
+
+#if defined(CONFIG_X2TLB)
+# if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
+#  define _PAGE_SZHUGE  (_PAGE_EXT_ESZ2)
+# elif defined(CONFIG_HUGETLB_PAGE_SIZE_256K)
+#  define _PAGE_SZHUGE  (_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ2)
+# elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
+#  define _PAGE_SZHUGE  (_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ1 | _PAGE_EXT_ESZ2)
+# elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
+#  define _PAGE_SZHUGE  (_PAGE_EXT_ESZ3)
+# elif defined(CONFIG_HUGETLB_PAGE_SIZE_64MB)
+#  define _PAGE_SZHUGE  (_PAGE_EXT_ESZ2 | _PAGE_EXT_ESZ3)
+# endif
+#else
+# if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
+#  define _PAGE_SZHUGE  (_PAGE_SZ1)
+# elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
+#  define _PAGE_SZHUGE  (_PAGE_SZ0 | _PAGE_SZ1)
+# endif
+#endif
+
+/*
+ * Stub out _PAGE_SZHUGE if we don't have a good definition for it,
+ * to make pte_mkhuge() happy.
+ */
+#ifndef _PAGE_SZHUGE
+# define _PAGE_SZHUGE   (_PAGE_FLAGS_HARD)
+#endif
+
+#define _PAGE_CHG_MASK \
+        (PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | _PAGE_DIRTY)
+
+#ifndef __ASSEMBLY__
+
+#if defined(CONFIG_X2TLB) /* SH-X2 TLB */
+#define PAGE_NONE       __pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
+
+#define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
+                                 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ  | \
+                                           _PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_USER_READ  | \
+                                           _PAGE_EXT_USER_WRITE))
+
+#define PAGE_EXECREAD   __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
+                                 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_EXEC | \
+                                           _PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_USER_EXEC | \
+                                           _PAGE_EXT_USER_READ))
+
+#define PAGE_COPY       PAGE_EXECREAD
+
+#define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
+                                 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_USER_READ))
+
+#define PAGE_WRITEONLY  __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
+                                 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_USER_WRITE))
+
+#define PAGE_RWX        __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
+                                 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_KERN_READ  | \
+                                           _PAGE_EXT_KERN_EXEC  | \
+                                           _PAGE_EXT_USER_WRITE | \
+                                           _PAGE_EXT_USER_READ  | \
+                                           _PAGE_EXT_USER_EXEC))
+
+#define PAGE_KERNEL     __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
+                                 _PAGE_DIRTY | _PAGE_ACCESSED | \
+                                 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_KERN_EXEC))
+
+#define PAGE_KERNEL_NOCACHE \
+                        __pgprot(_PAGE_PRESENT | _PAGE_DIRTY | \
+                                 _PAGE_ACCESSED | _PAGE_HW_SHARED | \
+                                 _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_KERN_EXEC))
+
+#define PAGE_KERNEL_RO  __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
+                                 _PAGE_DIRTY | _PAGE_ACCESSED | \
+                                 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_KERN_EXEC))
+
+#define PAGE_KERNEL_PCC(slot, type) \
+                        __pgprot(_PAGE_PRESENT | _PAGE_DIRTY | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD | \
+                                 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
+                                           _PAGE_EXT_KERN_WRITE | \
+                                           _PAGE_EXT_KERN_EXEC) \
+                                 (slot ? _PAGE_PCC_AREA5 : _PAGE_PCC_AREA6) | \
+                                 (type))
+
+#elif defined(CONFIG_MMU) /* SH-X TLB */
+#define PAGE_NONE       __pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
+
+#define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \
+                                 _PAGE_CACHABLE | _PAGE_ACCESSED | \
+                                 _PAGE_FLAGS_HARD)
+
+#define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
+
+#define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
+
+#define PAGE_EXECREAD   PAGE_READONLY
+#define PAGE_RWX        PAGE_SHARED
+#define PAGE_WRITEONLY  PAGE_SHARED
+
+#define PAGE_KERNEL     __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_CACHABLE | \
+                                 _PAGE_DIRTY | _PAGE_ACCESSED | \
+                                 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
+
+#define PAGE_KERNEL_NOCACHE \
+                        __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
+                                 _PAGE_ACCESSED | _PAGE_HW_SHARED | \
+                                 _PAGE_FLAGS_HARD)
+
+#define PAGE_KERNEL_RO  __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
+                                 _PAGE_DIRTY | _PAGE_ACCESSED | \
+                                 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
+
+#define PAGE_KERNEL_PCC(slot, type) \
+                        __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
+                                 _PAGE_ACCESSED | _PAGE_FLAGS_HARD | \
+                                 (slot ? _PAGE_PCC_AREA5 : _PAGE_PCC_AREA6) | \
+                                 (type))
+#else /* no mmu */
+#define PAGE_NONE               __pgprot(0)
+#define PAGE_SHARED             __pgprot(0)
+#define PAGE_COPY               __pgprot(0)
+#define PAGE_EXECREAD           __pgprot(0)
+#define PAGE_RWX                __pgprot(0)
+#define PAGE_READONLY           __pgprot(0)
+#define PAGE_WRITEONLY          __pgprot(0)
+#define PAGE_KERNEL             __pgprot(0)
+#define PAGE_KERNEL_NOCACHE     __pgprot(0)
+#define PAGE_KERNEL_RO          __pgprot(0)
+
+#define PAGE_KERNEL_PCC(slot, type) \
+                                __pgprot(0)
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Certain architectures need to do special things when PTEs
+ * within a page table are directly modified.  Thus, the following
+ * hook is made available.
+ */
+#ifdef CONFIG_X2TLB
+static inline void set_pte(pte_t *ptep, pte_t pte)
+{
+        ptep->pte_high = pte.pte_high;
+        smp_wmb();
+        ptep->pte_low = pte.pte_low;
+}
+#else
+#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
+#endif
+
+#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
+
+/*
+ * (pmds are folded into pgds so this doesn't get actually called,
+ * but the define is needed for a generic inline function.)
+ */
+#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
+
+#define pfn_pte(pfn, prot) \
+        __pte(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
+#define pfn_pmd(pfn, prot) \
+        __pmd(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
+
+#define pte_none(x)             (!pte_val(x))
+#define pte_present(x)          ((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
+
+#define pte_clear(mm,addr,xp) do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
+
+#define pmd_none(x)     (!pmd_val(x))
+#define pmd_present(x)  (pmd_val(x))
+#define pmd_clear(xp)   do { set_pmd(xp, __pmd(0)); } while (0)
+#define pmd_bad(x)      (pmd_val(x) & ~PAGE_MASK)
+
+#define pages_to_mb(x)  ((x) >> (20-PAGE_SHIFT))
+#define pte_page(x)     pfn_to_page(pte_pfn(x))
+
+/*
+ * The following only work if pte_present() is true.
+ * Undefined behaviour if not..
+ */
+#define pte_not_present(pte)    (!((pte).pte_low & _PAGE_PRESENT))
+#define pte_dirty(pte)          ((pte).pte_low & _PAGE_DIRTY)
+#define pte_young(pte)          ((pte).pte_low & _PAGE_ACCESSED)
+#define pte_file(pte)           ((pte).pte_low & _PAGE_FILE)
+
+#ifdef CONFIG_X2TLB
+#define pte_write(pte)          ((pte).pte_high & _PAGE_EXT_USER_WRITE)
+#else
+#define pte_write(pte)          ((pte).pte_low & _PAGE_RW)
+#endif
+
+#define PTE_BIT_FUNC(h,fn,op) \
+static inline pte_t pte_##fn(pte_t pte) { pte.pte_##h op; return pte; }
+
+#ifdef CONFIG_X2TLB
+/*
+ * We cheat a bit in the SH-X2 TLB case. As the permission bits are
+ * individually toggled (and user permissions are entirely decoupled from
+ * kernel permissions), we attempt to couple them a bit more sanely here.
+ */
+PTE_BIT_FUNC(high, wrprotect, &= ~_PAGE_EXT_USER_WRITE);
+PTE_BIT_FUNC(high, mkwrite, |= _PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE);
+PTE_BIT_FUNC(high, mkhuge, |= _PAGE_SZHUGE);
+#else
+PTE_BIT_FUNC(low, wrprotect, &= ~_PAGE_RW);
+PTE_BIT_FUNC(low, mkwrite, |= _PAGE_RW);
+PTE_BIT_FUNC(low, mkhuge, |= _PAGE_SZHUGE);
+#endif
+
+PTE_BIT_FUNC(low, mkclean, &= ~_PAGE_DIRTY);
+PTE_BIT_FUNC(low, mkdirty, |= _PAGE_DIRTY);
+PTE_BIT_FUNC(low, mkold, &= ~_PAGE_ACCESSED);
+PTE_BIT_FUNC(low, mkyoung, |= _PAGE_ACCESSED);
+
+/*
+ * Macro and implementation to make a page protection as uncachable.
+ */
+#define pgprot_writecombine(prot) \
+        __pgprot(pgprot_val(prot) & ~_PAGE_CACHABLE)
+
+#define pgprot_noncached         pgprot_writecombine
+
+/*
+ * Conversion functions: convert a page and protection to a page entry,
+ * and a page entry and page directory to the page they refer to.
+ *
+ * extern pte_t mk_pte(struct page *page, pgprot_t pgprot)
+ */
+#define mk_pte(page, pgprot)    pfn_pte(page_to_pfn(page), (pgprot))
+
+static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
+{
+        pte.pte_low &= _PAGE_CHG_MASK;
+        pte.pte_low |= pgprot_val(newprot);
+
+#ifdef CONFIG_X2TLB
+        pte.pte_high |= pgprot_val(newprot) >> 32;
+#endif
+
+        return pte;
+}
+
+#define pmd_page_vaddr(pmd)     ((unsigned long)pmd_val(pmd))
+#define pmd_page(pmd)           (virt_to_page(pmd_val(pmd)))
+
+/* to find an entry in a page-table-directory. */
+#define pgd_index(address)      (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
+#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))
+
+/* to find an entry in a kernel page-table-directory */
+#define pgd_offset_k(address)   pgd_offset(&init_mm, address)
+
+/* Find an entry in the third-level page table.. */
+#define pte_index(address)      ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
+#define pte_offset_kernel(dir, address) \
+        ((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(address))
+#define pte_offset_map(dir, address)            pte_offset_kernel(dir, address)
+#define pte_offset_map_nested(dir, address)     pte_offset_kernel(dir, address)
+
+#define pte_unmap(pte)          do { } while (0)
+#define pte_unmap_nested(pte)   do { } while (0)
+
+#ifdef CONFIG_X2TLB
+#define pte_ERROR(e) \
+        printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, \
+               &(e), (e).pte_high, (e).pte_low)
+#define pgd_ERROR(e) \
+        printk("%s:%d: bad pgd %016llx.\n", __FILE__, __LINE__, pgd_val(e))
+#else
+#define pte_ERROR(e) \
+        printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
+#define pgd_ERROR(e) \
+        printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
+#endif
+
+/*
+ * Encode and de-code a swap entry
+ *
+ * Constraints:
+ *      _PAGE_FILE at bit 0
+ *      _PAGE_PRESENT at bit 8
+ *      _PAGE_PROTNONE at bit 9
+ *
+ * For the normal case, we encode the swap type into bits 0:7 and the
+ * swap offset into bits 10:30. For the 64-bit PTE case, we keep the
+ * preserved bits in the low 32-bits and use the upper 32 as the swap
+ * offset (along with a 5-bit type), following the same approach as x86
+ * PAE. This keeps the logic quite simple, and allows for a full 32
+ * PTE_FILE_MAX_BITS, as opposed to the 29-bits we're constrained with
+ * in the pte_low case.
+ *
+ * As is evident by the Alpha code, if we ever get a 64-bit unsigned
+ * long (swp_entry_t) to match up with the 64-bit PTEs, this all becomes
+ * much cleaner..
+ *
+ * NOTE: We should set ZEROs at the position of _PAGE_PRESENT
+ *       and _PAGE_PROTNONE bits
+ */
+#ifdef CONFIG_X2TLB
+#define __swp_type(x)                   ((x).val & 0x1f)
+#define __swp_offset(x)                 ((x).val >> 5)
+#define __swp_entry(type, offset)       ((swp_entry_t){ (type) | (offset) << 5})
+#define __pte_to_swp_entry(pte)         ((swp_entry_t){ (pte).pte_high })
+#define __swp_entry_to_pte(x)           ((pte_t){ 0, (x).val })
+
+/*
+ * Encode and decode a nonlinear file mapping entry
+ */
+#define pte_to_pgoff(pte)               ((pte).pte_high)
+#define pgoff_to_pte(off)               ((pte_t) { _PAGE_FILE, (off) })
+
+#define PTE_FILE_MAX_BITS               32
+#else
+#define __swp_type(x)                   ((x).val & 0xff)
+#define __swp_offset(x)                 ((x).val >> 10)
+#define __swp_entry(type, offset)       ((swp_entry_t){(type) | (offset) <<10})
+
+#define __pte_to_swp_entry(pte)         ((swp_entry_t) { pte_val(pte) >> 1 })
+#define __swp_entry_to_pte(x)           ((pte_t) { (x).val << 1 })
+
+/*
+ * Encode and decode a nonlinear file mapping entry
+ */
+#define PTE_FILE_MAX_BITS       29
+#define pte_to_pgoff(pte)       (pte_val(pte) >> 1)
+#define pgoff_to_pte(off)       ((pte_t) { ((off) << 1) | _PAGE_FILE })
+#endif
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ASM_SH_PGTABLE_32_H */