Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 904 insertions, 0 deletions

diff --git a/arch/ppc64/mm/hugetlbpage.c b/arch/ppc64/mm/hugetlbpage.c
new file mode 100644
index 000000000000..c62ddaff0720
--- /dev/null
+++ b/arch/ppc64/mm/hugetlbpage.c
@@ -0,0 +1,904 @@
+/*
+ * PPC64 (POWER4) Huge TLB Page Support for Kernel.
+ *
+ * Copyright (C) 2003 David Gibson, IBM Corporation.
+ *
+ * Based on the IA-32 version:
+ * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/sysctl.h>
+#include <asm/mman.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+#include <asm/machdep.h>
+#include <asm/cputable.h>
+#include <asm/tlb.h>
+
+#include <linux/sysctl.h>
+
+#define HUGEPGDIR_SHIFT         (HPAGE_SHIFT + PAGE_SHIFT - 3)
+#define HUGEPGDIR_SIZE          (1UL << HUGEPGDIR_SHIFT)
+#define HUGEPGDIR_MASK          (~(HUGEPGDIR_SIZE-1))
+
+#define HUGEPTE_INDEX_SIZE      9
+#define HUGEPGD_INDEX_SIZE      10
+
+#define PTRS_PER_HUGEPTE        (1 << HUGEPTE_INDEX_SIZE)
+#define PTRS_PER_HUGEPGD        (1 << HUGEPGD_INDEX_SIZE)
+
+static inline int hugepgd_index(unsigned long addr)
+{
+        return (addr & ~REGION_MASK) >> HUGEPGDIR_SHIFT;
+}
+
+static pgd_t *hugepgd_offset(struct mm_struct *mm, unsigned long addr)
+{
+        int index;
+
+        if (! mm->context.huge_pgdir)
+                return NULL;
+
+
+        index = hugepgd_index(addr);
+        BUG_ON(index >= PTRS_PER_HUGEPGD);
+        return mm->context.huge_pgdir + index;
+}
+
+static inline pte_t *hugepte_offset(pgd_t *dir, unsigned long addr)
+{
+        int index;
+
+        if (pgd_none(*dir))
+                return NULL;
+
+        index = (addr >> HPAGE_SHIFT) % PTRS_PER_HUGEPTE;
+        return (pte_t *)pgd_page(*dir) + index;
+}
+
+static pgd_t *hugepgd_alloc(struct mm_struct *mm, unsigned long addr)
+{
+        BUG_ON(! in_hugepage_area(mm->context, addr));
+
+        if (! mm->context.huge_pgdir) {
+                pgd_t *new;
+                spin_unlock(&mm->page_table_lock);
+                /* Don't use pgd_alloc(), because we want __GFP_REPEAT */
+                new = kmem_cache_alloc(zero_cache, GFP_KERNEL | __GFP_REPEAT);
+                BUG_ON(memcmp(new, empty_zero_page, PAGE_SIZE));
+                spin_lock(&mm->page_table_lock);
+
+                /*
+                 * Because we dropped the lock, we should re-check the
+                 * entry, as somebody else could have populated it..
+                 */
+                if (mm->context.huge_pgdir)
+                        pgd_free(new);
+                else
+                        mm->context.huge_pgdir = new;
+        }
+        return hugepgd_offset(mm, addr);
+}
+
+static pte_t *hugepte_alloc(struct mm_struct *mm, pgd_t *dir,
+                            unsigned long addr)
+{
+        if (! pgd_present(*dir)) {
+                pte_t *new;
+
+                spin_unlock(&mm->page_table_lock);
+                new = kmem_cache_alloc(zero_cache, GFP_KERNEL | __GFP_REPEAT);
+                BUG_ON(memcmp(new, empty_zero_page, PAGE_SIZE));
+                spin_lock(&mm->page_table_lock);
+                /*
+                 * Because we dropped the lock, we should re-check the
+                 * entry, as somebody else could have populated it..
+                 */
+                if (pgd_present(*dir)) {
+                        if (new)
+                                kmem_cache_free(zero_cache, new);
+                } else {
+                        struct page *ptepage;
+
+                        if (! new)
+                                return NULL;
+                        ptepage = virt_to_page(new);
+                        ptepage->mapping = (void *) mm;
+                        ptepage->index = addr & HUGEPGDIR_MASK;
+                        pgd_populate(mm, dir, new);
+                }
+        }
+
+        return hugepte_offset(dir, addr);
+}
+
+static pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+
+        BUG_ON(! in_hugepage_area(mm->context, addr));
+
+        pgd = hugepgd_offset(mm, addr);
+        if (! pgd)
+                return NULL;
+
+        return hugepte_offset(pgd, addr);
+}
+
+static pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+
+        BUG_ON(! in_hugepage_area(mm->context, addr));
+
+        pgd = hugepgd_alloc(mm, addr);
+        if (! pgd)
+                return NULL;
+
+        return hugepte_alloc(mm, pgd, addr);
+}
+
+static void set_huge_pte(struct mm_struct *mm, struct vm_area_struct *vma,
+                         unsigned long addr, struct page *page,
+                         pte_t *ptep, int write_access)
+{
+        pte_t entry;
+
+        add_mm_counter(mm, rss, HPAGE_SIZE / PAGE_SIZE);
+        if (write_access) {
+                entry =
+                    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
+        } else {
+                entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
+        }
+        entry = pte_mkyoung(entry);
+        entry = pte_mkhuge(entry);
+
+        set_pte_at(mm, addr, ptep, entry);
+}
+
+/*
+ * This function checks for proper alignment of input addr and len parameters.
+ */
+int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
+{
+        if (len & ~HPAGE_MASK)
+                return -EINVAL;
+        if (addr & ~HPAGE_MASK)
+                return -EINVAL;
+        if (! (within_hugepage_low_range(addr, len)
+               || within_hugepage_high_range(addr, len)) )
+                return -EINVAL;
+        return 0;
+}
+
+static void flush_segments(void *parm)
+{
+        u16 segs = (unsigned long) parm;
+        unsigned long i;
+
+        asm volatile("isync" : : : "memory");
+
+        for (i = 0; i < 16; i++) {
+                if (! (segs & (1U << i)))
+                        continue;
+                asm volatile("slbie %0" : : "r" (i << SID_SHIFT));
+        }
+
+        asm volatile("isync" : : : "memory");
+}
+
+static int prepare_low_seg_for_htlb(struct mm_struct *mm, unsigned long seg)
+{
+        unsigned long start = seg << SID_SHIFT;
+        unsigned long end = (seg+1) << SID_SHIFT;
+        struct vm_area_struct *vma;
+        unsigned long addr;
+        struct mmu_gather *tlb;
+
+        BUG_ON(seg >= 16);
+
+        /* Check no VMAs are in the region */
+        vma = find_vma(mm, start);
+        if (vma && (vma->vm_start < end))
+                return -EBUSY;
+
+        /* Clean up any leftover PTE pages in the region */
+        spin_lock(&mm->page_table_lock);
+        tlb = tlb_gather_mmu(mm, 0);
+        for (addr = start; addr < end; addr += PMD_SIZE) {
+                pgd_t *pgd = pgd_offset(mm, addr);
+                pmd_t *pmd;
+                struct page *page;
+                pte_t *pte;
+                int i;
+
+                if (pgd_none(*pgd))
+                        continue;
+                pmd = pmd_offset(pgd, addr);
+                if (!pmd || pmd_none(*pmd))
+                        continue;
+                if (pmd_bad(*pmd)) {
+                        pmd_ERROR(*pmd);
+                        pmd_clear(pmd);
+                        continue;
+                }
+                pte = (pte_t *)pmd_page_kernel(*pmd);
+                /* No VMAs, so there should be no PTEs, check just in case. */
+                for (i = 0; i < PTRS_PER_PTE; i++) {
+                        BUG_ON(!pte_none(*pte));
+                        pte++;
+                }
+                page = pmd_page(*pmd);
+                pmd_clear(pmd);
+                mm->nr_ptes--;
+                dec_page_state(nr_page_table_pages);
+                pte_free_tlb(tlb, page);
+        }
+        tlb_finish_mmu(tlb, start, end);
+        spin_unlock(&mm->page_table_lock);
+
+        return 0;
+}
+
+static int open_low_hpage_segs(struct mm_struct *mm, u16 newsegs)
+{
+        unsigned long i;
+
+        newsegs &= ~(mm->context.htlb_segs);
+        if (! newsegs)
+                return 0; /* The segments we want are already open */
+
+        for (i = 0; i < 16; i++)
+                if ((1 << i) & newsegs)
+                        if (prepare_low_seg_for_htlb(mm, i) != 0)
+                                return -EBUSY;
+
+        mm->context.htlb_segs |= newsegs;
+
+        /* update the paca copy of the context struct */
+        get_paca()->context = mm->context;
+
+        /* the context change must make it to memory before the flush,
+         * so that further SLB misses do the right thing. */
+        mb();
+        on_each_cpu(flush_segments, (void *)(unsigned long)newsegs, 0, 1);
+
+        return 0;
+}
+
+int prepare_hugepage_range(unsigned long addr, unsigned long len)
+{
+        if (within_hugepage_high_range(addr, len))
+                return 0;
+        else if ((addr < 0x100000000UL) && ((addr+len) < 0x100000000UL)) {
+                int err;
+                /* Yes, we need both tests, in case addr+len overflows
+                 * 64-bit arithmetic */
+                err = open_low_hpage_segs(current->mm,
+                                          LOW_ESID_MASK(addr, len));
+                if (err)
+                        printk(KERN_DEBUG "prepare_hugepage_range(%lx, %lx)"
+                               " failed (segs: 0x%04hx)\n", addr, len,
+                               LOW_ESID_MASK(addr, len));
+                return err;
+        }
+
+        return -EINVAL;
+}
+
+int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
+                        struct vm_area_struct *vma)
+{
+        pte_t *src_pte, *dst_pte, entry;
+        struct page *ptepage;
+        unsigned long addr = vma->vm_start;
+        unsigned long end = vma->vm_end;
+        int err = -ENOMEM;
+
+        while (addr < end) {
+                dst_pte = huge_pte_alloc(dst, addr);
+                if (!dst_pte)
+                        goto out;
+
+                src_pte = huge_pte_offset(src, addr);
+                entry = *src_pte;
+                
+                ptepage = pte_page(entry);
+                get_page(ptepage);
+                add_mm_counter(dst, rss, HPAGE_SIZE / PAGE_SIZE);
+                set_pte_at(dst, addr, dst_pte, entry);
+
+                addr += HPAGE_SIZE;
+        }
+
+        err = 0;
+ out:
+        return err;
+}
+
+int
+follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
+                    struct page **pages, struct vm_area_struct **vmas,
+                    unsigned long *position, int *length, int i)
+{
+        unsigned long vpfn, vaddr = *position;
+        int remainder = *length;
+
+        WARN_ON(!is_vm_hugetlb_page(vma));
+
+        vpfn = vaddr/PAGE_SIZE;
+        while (vaddr < vma->vm_end && remainder) {
+                if (pages) {
+                        pte_t *pte;
+                        struct page *page;
+
+                        pte = huge_pte_offset(mm, vaddr);
+
+                        /* hugetlb should be locked, and hence, prefaulted */
+                        WARN_ON(!pte || pte_none(*pte));
+
+                        page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
+
+                        WARN_ON(!PageCompound(page));
+
+                        get_page(page);
+                        pages[i] = page;
+                }
+
+                if (vmas)
+                        vmas[i] = vma;
+
+                vaddr += PAGE_SIZE;
+                ++vpfn;
+                --remainder;
+                ++i;
+        }
+
+        *length = remainder;
+        *position = vaddr;
+
+        return i;
+}
+
+struct page *
+follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
+{
+        pte_t *ptep;
+        struct page *page;
+
+        if (! in_hugepage_area(mm->context, address))
+                return ERR_PTR(-EINVAL);
+
+        ptep = huge_pte_offset(mm, address);
+        page = pte_page(*ptep);
+        if (page)
+                page += (address % HPAGE_SIZE) / PAGE_SIZE;
+
+        return page;
+}
+
+int pmd_huge(pmd_t pmd)
+{
+        return 0;
+}
+
+struct page *
+follow_huge_pmd(struct mm_struct *mm, unsigned long address,
+                pmd_t *pmd, int write)
+{
+        BUG();
+        return NULL;
+}
+
+void unmap_hugepage_range(struct vm_area_struct *vma,
+                          unsigned long start, unsigned long end)
+{
+        struct mm_struct *mm = vma->vm_mm;
+        unsigned long addr;
+        pte_t *ptep;
+        struct page *page;
+
+        WARN_ON(!is_vm_hugetlb_page(vma));
+        BUG_ON((start % HPAGE_SIZE) != 0);
+        BUG_ON((end % HPAGE_SIZE) != 0);
+
+        for (addr = start; addr < end; addr += HPAGE_SIZE) {
+                pte_t pte;
+
+                ptep = huge_pte_offset(mm, addr);
+                if (!ptep || pte_none(*ptep))
+                        continue;
+
+                pte = *ptep;
+                page = pte_page(pte);
+                pte_clear(mm, addr, ptep);
+
+                put_page(page);
+        }
+        add_mm_counter(mm, rss, -((end - start) >> PAGE_SHIFT));
+        flush_tlb_pending();
+}
+
+void hugetlb_free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev,
+                           unsigned long start, unsigned long end)
+{
+        /* Because the huge pgtables are only 2 level, they can take
+         * at most around 4M, much less than one hugepage which the
+         * process is presumably entitled to use.  So we don't bother
+         * freeing up the pagetables on unmap, and wait until
+         * destroy_context() to clean up the lot. */
+}
+
+int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
+{
+        struct mm_struct *mm = current->mm;
+        unsigned long addr;
+        int ret = 0;
+
+        WARN_ON(!is_vm_hugetlb_page(vma));
+        BUG_ON((vma->vm_start % HPAGE_SIZE) != 0);
+        BUG_ON((vma->vm_end % HPAGE_SIZE) != 0);
+
+        spin_lock(&mm->page_table_lock);
+        for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
+                unsigned long idx;
+                pte_t *pte = huge_pte_alloc(mm, addr);
+                struct page *page;
+
+                if (!pte) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+                if (! pte_none(*pte))
+                        continue;
+
+                idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
+                        + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+                page = find_get_page(mapping, idx);
+                if (!page) {
+                        /* charge the fs quota first */
+                        if (hugetlb_get_quota(mapping)) {
+                                ret = -ENOMEM;
+                                goto out;
+                        }
+                        page = alloc_huge_page();
+                        if (!page) {
+                                hugetlb_put_quota(mapping);
+                                ret = -ENOMEM;
+                                goto out;
+                        }
+                        ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
+                        if (! ret) {
+                                unlock_page(page);
+                        } else {
+                                hugetlb_put_quota(mapping);
+                                free_huge_page(page);
+                                goto out;
+                        }
+                }
+                set_huge_pte(mm, vma, addr, page, pte, vma->vm_flags & VM_WRITE);
+        }
+out:
+        spin_unlock(&mm->page_table_lock);
+        return ret;
+}
+
+/* Because we have an exclusive hugepage region which lies within the
+ * normal user address space, we have to take special measures to make
+ * non-huge mmap()s evade the hugepage reserved regions. */
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
+                                     unsigned long len, unsigned long pgoff,
+                                     unsigned long flags)
+{
+        struct mm_struct *mm = current->mm;
+        struct vm_area_struct *vma;
+        unsigned long start_addr;
+
+        if (len > TASK_SIZE)
+                return -ENOMEM;
+
+        if (addr) {
+                addr = PAGE_ALIGN(addr);
+                vma = find_vma(mm, addr);
+                if (((TASK_SIZE - len) >= addr)
+                    && (!vma || (addr+len) <= vma->vm_start)
+                    && !is_hugepage_only_range(mm, addr,len))
+                        return addr;
+        }
+        start_addr = addr = mm->free_area_cache;
+
+full_search:
+        vma = find_vma(mm, addr);
+        while (TASK_SIZE - len >= addr) {
+                BUG_ON(vma && (addr >= vma->vm_end));
+
+                if (touches_hugepage_low_range(mm, addr, len)) {
+                        addr = ALIGN(addr+1, 1<<SID_SHIFT);
+                        vma = find_vma(mm, addr);
+                        continue;
+                }
+                if (touches_hugepage_high_range(addr, len)) {
+                        addr = TASK_HPAGE_END;
+                        vma = find_vma(mm, addr);
+                        continue;
+                }
+                if (!vma || addr + len <= vma->vm_start) {
+                        /*
+                         * Remember the place where we stopped the search:
+                         */
+                        mm->free_area_cache = addr + len;
+                        return addr;
+                }
+                addr = vma->vm_end;
+                vma = vma->vm_next;
+        }
+
+        /* Make sure we didn't miss any holes */
+        if (start_addr != TASK_UNMAPPED_BASE) {
+                start_addr = addr = TASK_UNMAPPED_BASE;
+                goto full_search;
+        }
+        return -ENOMEM;
+}
+
+/*
+ * This mmap-allocator allocates new areas top-down from below the
+ * stack's low limit (the base):
+ *
+ * Because we have an exclusive hugepage region which lies within the
+ * normal user address space, we have to take special measures to make
+ * non-huge mmap()s evade the hugepage reserved regions.
+ */
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+                          const unsigned long len, const unsigned long pgoff,
+                          const unsigned long flags)
+{
+        struct vm_area_struct *vma, *prev_vma;
+        struct mm_struct *mm = current->mm;
+        unsigned long base = mm->mmap_base, addr = addr0;
+        int first_time = 1;
+
+        /* requested length too big for entire address space */
+        if (len > TASK_SIZE)
+                return -ENOMEM;
+
+        /* dont allow allocations above current base */
+        if (mm->free_area_cache > base)
+                mm->free_area_cache = base;
+
+        /* requesting a specific address */
+        if (addr) {
+                addr = PAGE_ALIGN(addr);
+                vma = find_vma(mm, addr);
+                if (TASK_SIZE - len >= addr &&
+                                (!vma || addr + len <= vma->vm_start)
+                                && !is_hugepage_only_range(mm, addr,len))
+                        return addr;
+        }
+
+try_again:
+        /* make sure it can fit in the remaining address space */
+        if (mm->free_area_cache < len)
+                goto fail;
+
+        /* either no address requested or cant fit in requested address hole */
+        addr = (mm->free_area_cache - len) & PAGE_MASK;
+        do {
+hugepage_recheck:
+                if (touches_hugepage_low_range(mm, addr, len)) {
+                        addr = (addr & ((~0) << SID_SHIFT)) - len;
+                        goto hugepage_recheck;
+                } else if (touches_hugepage_high_range(addr, len)) {
+                        addr = TASK_HPAGE_BASE - len;
+                }
+
+                /*
+                 * Lookup failure means no vma is above this address,
+                 * i.e. return with success:
+                 */
+                if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
+                        return addr;
+
+                /*
+                 * new region fits between prev_vma->vm_end and
+                 * vma->vm_start, use it:
+                 */
+                if (addr+len <= vma->vm_start &&
+                                (!prev_vma || (addr >= prev_vma->vm_end)))
+                        /* remember the address as a hint for next time */
+                        return (mm->free_area_cache = addr);
+                else
+                        /* pull free_area_cache down to the first hole */
+                        if (mm->free_area_cache == vma->vm_end)
+                                mm->free_area_cache = vma->vm_start;
+
+                /* try just below the current vma->vm_start */
+                addr = vma->vm_start-len;
+        } while (len <= vma->vm_start);
+
+fail:
+        /*
+         * if hint left us with no space for the requested
+         * mapping then try again:
+         */
+        if (first_time) {
+                mm->free_area_cache = base;
+                first_time = 0;
+                goto try_again;
+        }
+        /*
+         * A failed mmap() very likely causes application failure,
+         * so fall back to the bottom-up function here. This scenario
+         * can happen with large stack limits and large mmap()
+         * allocations.
+         */
+        mm->free_area_cache = TASK_UNMAPPED_BASE;
+        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+        /*
+         * Restore the topdown base:
+         */
+        mm->free_area_cache = base;
+
+        return addr;
+}
+
+static unsigned long htlb_get_low_area(unsigned long len, u16 segmask)
+{
+        unsigned long addr = 0;
+        struct vm_area_struct *vma;
+
+        vma = find_vma(current->mm, addr);
+        while (addr + len <= 0x100000000UL) {
+                BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
+
+                if (! __within_hugepage_low_range(addr, len, segmask)) {
+                        addr = ALIGN(addr+1, 1<<SID_SHIFT);
+                        vma = find_vma(current->mm, addr);
+                        continue;
+                }
+
+                if (!vma || (addr + len) <= vma->vm_start)
+                        return addr;
+                addr = ALIGN(vma->vm_end, HPAGE_SIZE);
+                /* Depending on segmask this might not be a confirmed
+                 * hugepage region, so the ALIGN could have skipped
+                 * some VMAs */
+                vma = find_vma(current->mm, addr);
+        }
+
+        return -ENOMEM;
+}
+
+static unsigned long htlb_get_high_area(unsigned long len)
+{
+        unsigned long addr = TASK_HPAGE_BASE;
+        struct vm_area_struct *vma;
+
+        vma = find_vma(current->mm, addr);
+        for (vma = find_vma(current->mm, addr);
+             addr + len <= TASK_HPAGE_END;
+             vma = vma->vm_next) {
+                BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
+                BUG_ON(! within_hugepage_high_range(addr, len));
+
+                if (!vma || (addr + len) <= vma->vm_start)
+                        return addr;
+                addr = ALIGN(vma->vm_end, HPAGE_SIZE);
+                /* Because we're in a hugepage region, this alignment
+                 * should not skip us over any VMAs */
+        }
+
+        return -ENOMEM;
+}
+
+unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+                                        unsigned long len, unsigned long pgoff,
+                                        unsigned long flags)
+{
+        if (len & ~HPAGE_MASK)
+                return -EINVAL;
+
+        if (!cpu_has_feature(CPU_FTR_16M_PAGE))
+                return -EINVAL;
+
+        if (test_thread_flag(TIF_32BIT)) {
+                int lastshift = 0;
+                u16 segmask, cursegs = current->mm->context.htlb_segs;
+
+                /* First see if we can do the mapping in the existing
+                 * low hpage segments */
+                addr = htlb_get_low_area(len, cursegs);
+                if (addr != -ENOMEM)
+                        return addr;
+
+                for (segmask = LOW_ESID_MASK(0x100000000UL-len, len);
+                     ! lastshift; segmask >>=1) {
+                        if (segmask & 1)
+                                lastshift = 1;
+
+                        addr = htlb_get_low_area(len, cursegs | segmask);
+                        if ((addr != -ENOMEM)
+                            && open_low_hpage_segs(current->mm, segmask) == 0)
+                                return addr;
+                }
+                printk(KERN_DEBUG "hugetlb_get_unmapped_area() unable to open"
+                       " enough segments\n");
+                return -ENOMEM;
+        } else {
+                return htlb_get_high_area(len);
+        }
+}
+
+void hugetlb_mm_free_pgd(struct mm_struct *mm)
+{
+        int i;
+        pgd_t *pgdir;
+
+        spin_lock(&mm->page_table_lock);
+
+        pgdir = mm->context.huge_pgdir;
+        if (! pgdir)
+                goto out;
+
+        mm->context.huge_pgdir = NULL;
+
+        /* cleanup any hugepte pages leftover */
+        for (i = 0; i < PTRS_PER_HUGEPGD; i++) {
+                pgd_t *pgd = pgdir + i;
+
+                if (! pgd_none(*pgd)) {
+                        pte_t *pte = (pte_t *)pgd_page(*pgd);
+                        struct page *ptepage = virt_to_page(pte);
+
+                        ptepage->mapping = NULL;
+
+                        BUG_ON(memcmp(pte, empty_zero_page, PAGE_SIZE));
+                        kmem_cache_free(zero_cache, pte);
+                }
+                pgd_clear(pgd);
+        }
+
+        BUG_ON(memcmp(pgdir, empty_zero_page, PAGE_SIZE));
+        kmem_cache_free(zero_cache, pgdir);
+
+ out:
+        spin_unlock(&mm->page_table_lock);
+}
+
+int hash_huge_page(struct mm_struct *mm, unsigned long access,
+                   unsigned long ea, unsigned long vsid, int local)
+{
+        pte_t *ptep;
+        unsigned long va, vpn;
+        pte_t old_pte, new_pte;
+        unsigned long hpteflags, prpn;
+        long slot;
+        int err = 1;
+
+        spin_lock(&mm->page_table_lock);
+
+        ptep = huge_pte_offset(mm, ea);
+
+        /* Search the Linux page table for a match with va */
+        va = (vsid << 28) | (ea & 0x0fffffff);
+        vpn = va >> HPAGE_SHIFT;
+
+        /*
+         * If no pte found or not present, send the problem up to
+         * do_page_fault
+         */
+        if (unlikely(!ptep || pte_none(*ptep)))
+                goto out;
+
+/*      BUG_ON(pte_bad(*ptep)); */
+
+        /* 
+         * Check the user's access rights to the page.  If access should be
+         * prevented then send the problem up to do_page_fault.
+         */
+        if (unlikely(access & ~pte_val(*ptep)))
+                goto out;
+        /*
+         * At this point, we have a pte (old_pte) which can be used to build
+         * or update an HPTE. There are 2 cases:
+         *
+         * 1. There is a valid (present) pte with no associated HPTE (this is 
+         *      the most common case)
+         * 2. There is a valid (present) pte with an associated HPTE. The
+         *      current values of the pp bits in the HPTE prevent access
+         *      because we are doing software DIRTY bit management and the
+         *      page is currently not DIRTY. 
+         */
+
+
+        old_pte = *ptep;
+        new_pte = old_pte;
+
+        hpteflags = 0x2 | (! (pte_val(new_pte) & _PAGE_RW));
+        /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
+        hpteflags |= ((pte_val(new_pte) & _PAGE_EXEC) ? 0 : HW_NO_EXEC);
+
+        /* Check if pte already has an hpte (case 2) */
+        if (unlikely(pte_val(old_pte) & _PAGE_HASHPTE)) {
+                /* There MIGHT be an HPTE for this pte */
+                unsigned long hash, slot;
+
+                hash = hpt_hash(vpn, 1);
+                if (pte_val(old_pte) & _PAGE_SECONDARY)
+                        hash = ~hash;
+                slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
+                slot += (pte_val(old_pte) & _PAGE_GROUP_IX) >> 12;
+
+                if (ppc_md.hpte_updatepp(slot, hpteflags, va, 1, local) == -1)
+                        pte_val(old_pte) &= ~_PAGE_HPTEFLAGS;
+        }
+
+        if (likely(!(pte_val(old_pte) & _PAGE_HASHPTE))) {
+                unsigned long hash = hpt_hash(vpn, 1);
+                unsigned long hpte_group;
+
+                prpn = pte_pfn(old_pte);
+
+repeat:
+                hpte_group = ((hash & htab_hash_mask) *
+                              HPTES_PER_GROUP) & ~0x7UL;
+
+                /* Update the linux pte with the HPTE slot */
+                pte_val(new_pte) &= ~_PAGE_HPTEFLAGS;
+                pte_val(new_pte) |= _PAGE_HASHPTE;
+
+                /* Add in WIMG bits */
+                /* XXX We should store these in the pte */
+                hpteflags |= _PAGE_COHERENT;
+
+                slot = ppc_md.hpte_insert(hpte_group, va, prpn, 0,
+                                          hpteflags, 0, 1);
+
+                /* Primary is full, try the secondary */
+                if (unlikely(slot == -1)) {
+                        pte_val(new_pte) |= _PAGE_SECONDARY;
+                        hpte_group = ((~hash & htab_hash_mask) *
+                                      HPTES_PER_GROUP) & ~0x7UL; 
+                        slot = ppc_md.hpte_insert(hpte_group, va, prpn,
+                                                  1, hpteflags, 0, 1);
+                        if (slot == -1) {
+                                if (mftb() & 0x1)
+                                        hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
+
+                                ppc_md.hpte_remove(hpte_group);
+                                goto repeat;
+                        }
+                }
+
+                if (unlikely(slot == -2))
+                        panic("hash_huge_page: pte_insert failed\n");
+
+                pte_val(new_pte) |= (slot<<12) & _PAGE_GROUP_IX;
+
+                /* 
+                 * No need to use ldarx/stdcx here because all who
+                 * might be updating the pte will hold the
+                 * page_table_lock
+                 */
+                *ptep = new_pte;
+        }
+
+        err = 0;
+
+ out:
+        spin_unlock(&mm->page_table_lock);
+
+        return err;
+}