Initial import

1 files changed, 1113 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
new file mode 100644
index 000000000..3385e3d05
--- /dev/null
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -0,0 +1,1113 @@
+/*
+ * PPC Huge TLB Page Support for Kernel.
+ *
+ * Copyright (C) 2003 David Gibson, IBM Corporation.
+ * Copyright (C) 2011 Becky Bruce, Freescale Semiconductor
+ *
+ * Based on the IA-32 version:
+ * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/hugetlb.h>
+#include <linux/export.h>
+#include <linux/of_fdt.h>
+#include <linux/memblock.h>
+#include <linux/bootmem.h>
+#include <linux/moduleparam.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+#include <asm/setup.h>
+#include <asm/hugetlb.h>
+
+#ifdef CONFIG_HUGETLB_PAGE
+
+#define PAGE_SHIFT_64K	16
+#define PAGE_SHIFT_16M	24
+#define PAGE_SHIFT_16G	34
+
+unsigned int HPAGE_SHIFT;
+
+/*
+ * Tracks gpages after the device tree is scanned and before the
+ * huge_boot_pages list is ready.  On non-Freescale implementations, this is
+ * just used to track 16G pages and so is a single array.  FSL-based
+ * implementations may have more than one gpage size, so we need multiple
+ * arrays
+ */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+#define MAX_NUMBER_GPAGES	128
+struct psize_gpages {
+	u64 gpage_list[MAX_NUMBER_GPAGES];
+	unsigned int nr_gpages;
+};
+static struct psize_gpages gpage_freearray[MMU_PAGE_COUNT];
+#else
+#define MAX_NUMBER_GPAGES	1024
+static u64 gpage_freearray[MAX_NUMBER_GPAGES];
+static unsigned nr_gpages;
+#endif
+
+#define hugepd_none(hpd)	((hpd).pd == 0)
+
+#ifdef CONFIG_PPC_BOOK3S_64
+/*
+ * At this point we do the placement change only for BOOK3S 64. This would
+ * possibly work on other subarchs.
+ */
+
+/*
+ * We have PGD_INDEX_SIZ = 12 and PTE_INDEX_SIZE = 8, so that we can have
+ * 16GB hugepage pte in PGD and 16MB hugepage pte at PMD;
+ *
+ * Defined in such a way that we can optimize away code block at build time
+ * if CONFIG_HUGETLB_PAGE=n.
+ */
+int pmd_huge(pmd_t pmd)
+{
+	/*
+	 * leaf pte for huge page, bottom two bits != 00
+	 */
+	return ((pmd_val(pmd) & 0x3) != 0x0);
+}
+
+int pud_huge(pud_t pud)
+{
+	/*
+	 * leaf pte for huge page, bottom two bits != 00
+	 */
+	return ((pud_val(pud) & 0x3) != 0x0);
+}
+
+int pgd_huge(pgd_t pgd)
+{
+	/*
+	 * leaf pte for huge page, bottom two bits != 00
+	 */
+	return ((pgd_val(pgd) & 0x3) != 0x0);
+}
+#else
+int pmd_huge(pmd_t pmd)
+{
+	return 0;
+}
+
+int pud_huge(pud_t pud)
+{
+	return 0;
+}
+
+int pgd_huge(pgd_t pgd)
+{
+	return 0;
+}
+#endif
+
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+	/* Only called for hugetlbfs pages, hence can ignore THP */
+	return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL);
+}
+
+static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
+			   unsigned long address, unsigned pdshift, unsigned pshift)
+{
+	struct kmem_cache *cachep;
+	pte_t *new;
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	int i;
+	int num_hugepd = 1 << (pshift - pdshift);
+	cachep = hugepte_cache;
+#else
+	cachep = PGT_CACHE(pdshift - pshift);
+#endif
+
+	new = kmem_cache_zalloc(cachep, GFP_KERNEL|__GFP_REPEAT);
+
+	BUG_ON(pshift > HUGEPD_SHIFT_MASK);
+	BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
+
+	if (! new)
+		return -ENOMEM;
+
+	spin_lock(&mm->page_table_lock);
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	/*
+	 * We have multiple higher-level entries that point to the same
+	 * actual pte location.  Fill in each as we go and backtrack on error.
+	 * We need all of these so the DTLB pgtable walk code can find the
+	 * right higher-level entry without knowing if it's a hugepage or not.
+	 */
+	for (i = 0; i < num_hugepd; i++, hpdp++) {
+		if (unlikely(!hugepd_none(*hpdp)))
+			break;
+		else
+			/* We use the old format for PPC_FSL_BOOK3E */
+			hpdp->pd = ((unsigned long)new & ~PD_HUGE) | pshift;
+	}
+	/* If we bailed from the for loop early, an error occurred, clean up */
+	if (i < num_hugepd) {
+		for (i = i - 1 ; i >= 0; i--, hpdp--)
+			hpdp->pd = 0;
+		kmem_cache_free(cachep, new);
+	}
+#else
+	if (!hugepd_none(*hpdp))
+		kmem_cache_free(cachep, new);
+	else {
+#ifdef CONFIG_PPC_BOOK3S_64
+		hpdp->pd = (unsigned long)new |
+			    (shift_to_mmu_psize(pshift) << 2);
+#else
+		hpdp->pd = ((unsigned long)new & ~PD_HUGE) | pshift;
+#endif
+	}
+#endif
+	spin_unlock(&mm->page_table_lock);
+	return 0;
+}
+
+/*
+ * These macros define how to determine which level of the page table holds
+ * the hpdp.
+ */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+#define HUGEPD_PGD_SHIFT PGDIR_SHIFT
+#define HUGEPD_PUD_SHIFT PUD_SHIFT
+#else
+#define HUGEPD_PGD_SHIFT PUD_SHIFT
+#define HUGEPD_PUD_SHIFT PMD_SHIFT
+#endif
+
+#ifdef CONFIG_PPC_BOOK3S_64
+/*
+ * At this point we do the placement change only for BOOK3S 64. This would
+ * possibly work on other subarchs.
+ */
+pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
+{
+	pgd_t *pg;
+	pud_t *pu;
+	pmd_t *pm;
+	hugepd_t *hpdp = NULL;
+	unsigned pshift = __ffs(sz);
+	unsigned pdshift = PGDIR_SHIFT;
+
+	addr &= ~(sz-1);
+	pg = pgd_offset(mm, addr);
+
+	if (pshift == PGDIR_SHIFT)
+		/* 16GB huge page */
+		return (pte_t *) pg;
+	else if (pshift > PUD_SHIFT)
+		/*
+		 * We need to use hugepd table
+		 */
+		hpdp = (hugepd_t *)pg;
+	else {
+		pdshift = PUD_SHIFT;
+		pu = pud_alloc(mm, pg, addr);
+		if (pshift == PUD_SHIFT)
+			return (pte_t *)pu;
+		else if (pshift > PMD_SHIFT)
+			hpdp = (hugepd_t *)pu;
+		else {
+			pdshift = PMD_SHIFT;
+			pm = pmd_alloc(mm, pu, addr);
+			if (pshift == PMD_SHIFT)
+				/* 16MB hugepage */
+				return (pte_t *)pm;
+			else
+				hpdp = (hugepd_t *)pm;
+		}
+	}
+	if (!hpdp)
+		return NULL;
+
+	BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
+
+	if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
+		return NULL;
+
+	return hugepte_offset(*hpdp, addr, pdshift);
+}
+
+#else
+
+pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
+{
+	pgd_t *pg;
+	pud_t *pu;
+	pmd_t *pm;
+	hugepd_t *hpdp = NULL;
+	unsigned pshift = __ffs(sz);
+	unsigned pdshift = PGDIR_SHIFT;
+
+	addr &= ~(sz-1);
+
+	pg = pgd_offset(mm, addr);
+
+	if (pshift >= HUGEPD_PGD_SHIFT) {
+		hpdp = (hugepd_t *)pg;
+	} else {
+		pdshift = PUD_SHIFT;
+		pu = pud_alloc(mm, pg, addr);
+		if (pshift >= HUGEPD_PUD_SHIFT) {
+			hpdp = (hugepd_t *)pu;
+		} else {
+			pdshift = PMD_SHIFT;
+			pm = pmd_alloc(mm, pu, addr);
+			hpdp = (hugepd_t *)pm;
+		}
+	}
+
+	if (!hpdp)
+		return NULL;
+
+	BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
+
+	if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
+		return NULL;
+
+	return hugepte_offset(*hpdp, addr, pdshift);
+}
+#endif
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+/* Build list of addresses of gigantic pages.  This function is used in early
+ * boot before the buddy allocator is setup.
+ */
+void add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
+{
+	unsigned int idx = shift_to_mmu_psize(__ffs(page_size));
+	int i;
+
+	if (addr == 0)
+		return;
+
+	gpage_freearray[idx].nr_gpages = number_of_pages;
+
+	for (i = 0; i < number_of_pages; i++) {
+		gpage_freearray[idx].gpage_list[i] = addr;
+		addr += page_size;
+	}
+}
+
+/*
+ * Moves the gigantic page addresses from the temporary list to the
+ * huge_boot_pages list.
+ */
+int alloc_bootmem_huge_page(struct hstate *hstate)
+{
+	struct huge_bootmem_page *m;
+	int idx = shift_to_mmu_psize(huge_page_shift(hstate));
+	int nr_gpages = gpage_freearray[idx].nr_gpages;
+
+	if (nr_gpages == 0)
+		return 0;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * If gpages can be in highmem we can't use the trick of storing the
+	 * data structure in the page; allocate space for this
+	 */
+	m = memblock_virt_alloc(sizeof(struct huge_bootmem_page), 0);
+	m->phys = gpage_freearray[idx].gpage_list[--nr_gpages];
+#else
+	m = phys_to_virt(gpage_freearray[idx].gpage_list[--nr_gpages]);
+#endif
+
+	list_add(&m->list, &huge_boot_pages);
+	gpage_freearray[idx].nr_gpages = nr_gpages;
+	gpage_freearray[idx].gpage_list[nr_gpages] = 0;
+	m->hstate = hstate;
+
+	return 1;
+}
+/*
+ * Scan the command line hugepagesz= options for gigantic pages; store those in
+ * a list that we use to allocate the memory once all options are parsed.
+ */
+
+unsigned long gpage_npages[MMU_PAGE_COUNT];
+
+static int __init do_gpage_early_setup(char *param, char *val,
+				       const char *unused)
+{
+	static phys_addr_t size;
+	unsigned long npages;
+
+	/*
+	 * The hugepagesz and hugepages cmdline options are interleaved.  We
+	 * use the size variable to keep track of whether or not this was done
+	 * properly and skip over instances where it is incorrect.  Other
+	 * command-line parsing code will issue warnings, so we don't need to.
+	 *
+	 */
+	if ((strcmp(param, "default_hugepagesz") == 0) ||
+	    (strcmp(param, "hugepagesz") == 0)) {
+		size = memparse(val, NULL);
+	} else if (strcmp(param, "hugepages") == 0) {
+		if (size != 0) {
+			if (sscanf(val, "%lu", &npages) <= 0)
+				npages = 0;
+			if (npages > MAX_NUMBER_GPAGES) {
+				pr_warn("MMU: %lu pages requested for page "
+					"size %llu KB, limiting to "
+					__stringify(MAX_NUMBER_GPAGES) "\n",
+					npages, size / 1024);
+				npages = MAX_NUMBER_GPAGES;
+			}
+			gpage_npages[shift_to_mmu_psize(__ffs(size))] = npages;
+			size = 0;
+		}
+	}
+	return 0;
+}
+
+
+/*
+ * This function allocates physical space for pages that are larger than the
+ * buddy allocator can handle.  We want to allocate these in highmem because
+ * the amount of lowmem is limited.  This means that this function MUST be
+ * called before lowmem_end_addr is set up in MMU_init() in order for the lmb
+ * allocate to grab highmem.
+ */
+void __init reserve_hugetlb_gpages(void)
+{
+	static __initdata char cmdline[COMMAND_LINE_SIZE];
+	phys_addr_t size, base;
+	int i;
+
+	strlcpy(cmdline, boot_command_line, COMMAND_LINE_SIZE);
+	parse_args("hugetlb gpages", cmdline, NULL, 0, 0, 0,
+			&do_gpage_early_setup);
+
+	/*
+	 * Walk gpage list in reverse, allocating larger page sizes first.
+	 * Skip over unsupported sizes, or sizes that have 0 gpages allocated.
+	 * When we reach the point in the list where pages are no longer
+	 * considered gpages, we're done.
+	 */
+	for (i = MMU_PAGE_COUNT-1; i >= 0; i--) {
+		if (mmu_psize_defs[i].shift == 0 || gpage_npages[i] == 0)
+			continue;
+		else if (mmu_psize_to_shift(i) < (MAX_ORDER + PAGE_SHIFT))
+			break;
+
+		size = (phys_addr_t)(1ULL << mmu_psize_to_shift(i));
+		base = memblock_alloc_base(size * gpage_npages[i], size,
+					   MEMBLOCK_ALLOC_ANYWHERE);
+		add_gpage(base, size, gpage_npages[i]);
+	}
+}
+
+#else /* !PPC_FSL_BOOK3E */
+
+/* Build list of addresses of gigantic pages.  This function is used in early
+ * boot before the buddy allocator is setup.
+ */
+void add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
+{
+	if (!addr)
+		return;
+	while (number_of_pages > 0) {
+		gpage_freearray[nr_gpages] = addr;
+		nr_gpages++;
+		number_of_pages--;
+		addr += page_size;
+	}
+}
+
+/* Moves the gigantic page addresses from the temporary list to the
+ * huge_boot_pages list.
+ */
+int alloc_bootmem_huge_page(struct hstate *hstate)
+{
+	struct huge_bootmem_page *m;
+	if (nr_gpages == 0)
+		return 0;
+	m = phys_to_virt(gpage_freearray[--nr_gpages]);
+	gpage_freearray[nr_gpages] = 0;
+	list_add(&m->list, &huge_boot_pages);
+	m->hstate = hstate;
+	return 1;
+}
+#endif
+
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	return 0;
+}
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+#define HUGEPD_FREELIST_SIZE \
+	((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
+
+struct hugepd_freelist {
+	struct rcu_head	rcu;
+	unsigned int index;
+	void *ptes[0];
+};
+
+static DEFINE_PER_CPU(struct hugepd_freelist *, hugepd_freelist_cur);
+
+static void hugepd_free_rcu_callback(struct rcu_head *head)
+{
+	struct hugepd_freelist *batch =
+		container_of(head, struct hugepd_freelist, rcu);
+	unsigned int i;
+
+	for (i = 0; i < batch->index; i++)
+		kmem_cache_free(hugepte_cache, batch->ptes[i]);
+
+	free_page((unsigned long)batch);
+}
+
+static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
+{
+	struct hugepd_freelist **batchp;
+
+	batchp = this_cpu_ptr(&hugepd_freelist_cur);
+
+	if (atomic_read(&tlb->mm->mm_users) < 2 ||
+	    cpumask_equal(mm_cpumask(tlb->mm),
+			  cpumask_of(smp_processor_id()))) {
+		kmem_cache_free(hugepte_cache, hugepte);
+        put_cpu_var(hugepd_freelist_cur);
+		return;
+	}
+
+	if (*batchp == NULL) {
+		*batchp = (struct hugepd_freelist *)__get_free_page(GFP_ATOMIC);
+		(*batchp)->index = 0;
+	}
+
+	(*batchp)->ptes[(*batchp)->index++] = hugepte;
+	if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
+		call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
+		*batchp = NULL;
+	}
+	put_cpu_var(hugepd_freelist_cur);
+}
+#endif
+
+static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
+			      unsigned long start, unsigned long end,
+			      unsigned long floor, unsigned long ceiling)
+{
+	pte_t *hugepte = hugepd_page(*hpdp);
+	int i;
+
+	unsigned long pdmask = ~((1UL << pdshift) - 1);
+	unsigned int num_hugepd = 1;
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	/* Note: On fsl the hpdp may be the first of several */
+	num_hugepd = (1 << (hugepd_shift(*hpdp) - pdshift));
+#else
+	unsigned int shift = hugepd_shift(*hpdp);
+#endif
+
+	start &= pdmask;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= pdmask;
+		if (! ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	for (i = 0; i < num_hugepd; i++, hpdp++)
+		hpdp->pd = 0;
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	hugepd_free(tlb, hugepte);
+#else
+	pgtable_free_tlb(tlb, hugepte, pdshift - shift);
+#endif
+}
+
+static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+				   unsigned long addr, unsigned long end,
+				   unsigned long floor, unsigned long ceiling)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	do {
+		pmd = pmd_offset(pud, addr);
+		next = pmd_addr_end(addr, end);
+		if (!is_hugepd(__hugepd(pmd_val(*pmd)))) {
+			/*
+			 * if it is not hugepd pointer, we should already find
+			 * it cleared.
+			 */
+			WARN_ON(!pmd_none_or_clear_bad(pmd));
+			continue;
+		}
+#ifdef CONFIG_PPC_FSL_BOOK3E
+		/*
+		 * Increment next by the size of the huge mapping since
+		 * there may be more than one entry at this level for a
+		 * single hugepage, but all of them point to
+		 * the same kmem cache that holds the hugepte.
+		 */
+		next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
+#endif
+		free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
+				  addr, next, floor, ceiling);
+	} while (addr = next, addr != end);
+
+	start &= PUD_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PUD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pmd = pmd_offset(pud, start);
+	pud_clear(pud);
+	pmd_free_tlb(tlb, pmd, start);
+	mm_dec_nr_pmds(tlb->mm);
+}
+
+static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
+				   unsigned long addr, unsigned long end,
+				   unsigned long floor, unsigned long ceiling)
+{
+	pud_t *pud;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	do {
+		pud = pud_offset(pgd, addr);
+		next = pud_addr_end(addr, end);
+		if (!is_hugepd(__hugepd(pud_val(*pud)))) {
+			if (pud_none_or_clear_bad(pud))
+				continue;
+			hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
+					       ceiling);
+		} else {
+#ifdef CONFIG_PPC_FSL_BOOK3E
+			/*
+			 * Increment next by the size of the huge mapping since
+			 * there may be more than one entry at this level for a
+			 * single hugepage, but all of them point to
+			 * the same kmem cache that holds the hugepte.
+			 */
+			next = addr + (1 << hugepd_shift(*(hugepd_t *)pud));
+#endif
+			free_hugepd_range(tlb, (hugepd_t *)pud, PUD_SHIFT,
+					  addr, next, floor, ceiling);
+		}
+	} while (addr = next, addr != end);
+
+	start &= PGDIR_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PGDIR_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pud = pud_offset(pgd, start);
+	pgd_clear(pgd);
+	pud_free_tlb(tlb, pud, start);
+}
+
+/*
+ * This function frees user-level page tables of a process.
+ */
+void hugetlb_free_pgd_range(struct mmu_gather *tlb,
+			    unsigned long addr, unsigned long end,
+			    unsigned long floor, unsigned long ceiling)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	/*
+	 * Because there are a number of different possible pagetable
+	 * layouts for hugepage ranges, we limit knowledge of how
+	 * things should be laid out to the allocation path
+	 * (huge_pte_alloc(), above).  Everything else works out the
+	 * structure as it goes from information in the hugepd
+	 * pointers.  That means that we can't here use the
+	 * optimization used in the normal page free_pgd_range(), of
+	 * checking whether we're actually covering a large enough
+	 * range to have to do anything at the top level of the walk
+	 * instead of at the bottom.
+	 *
+	 * To make sense of this, you should probably go read the big
+	 * block comment at the top of the normal free_pgd_range(),
+	 * too.
+	 */
+
+	do {
+		next = pgd_addr_end(addr, end);
+		pgd = pgd_offset(tlb->mm, addr);
+		if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
+			if (pgd_none_or_clear_bad(pgd))
+				continue;
+			hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
+		} else {
+#ifdef CONFIG_PPC_FSL_BOOK3E
+			/*
+			 * Increment next by the size of the huge mapping since
+			 * there may be more than one entry at the pgd level
+			 * for a single hugepage, but all of them point to the
+			 * same kmem cache that holds the hugepte.
+			 */
+			next = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
+#endif
+			free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
+					  addr, next, floor, ceiling);
+		}
+	} while (addr = next, addr != end);
+}
+
+/*
+ * We are holding mmap_sem, so a parallel huge page collapse cannot run.
+ * To prevent hugepage split, disable irq.
+ */
+struct page *
+follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
+{
+	pte_t *ptep, pte;
+	unsigned shift;
+	unsigned long mask, flags;
+	struct page *page = ERR_PTR(-EINVAL);
+
+	local_irq_save(flags);
+	ptep = find_linux_pte_or_hugepte(mm->pgd, address, &shift);
+	if (!ptep)
+		goto no_page;
+	pte = READ_ONCE(*ptep);
+	/*
+	 * Verify it is a huge page else bail.
+	 * Transparent hugepages are handled by generic code. We can skip them
+	 * here.
+	 */
+	if (!shift || pmd_trans_huge(__pmd(pte_val(pte))))
+		goto no_page;
+
+	if (!pte_present(pte)) {
+		page = NULL;
+		goto no_page;
+	}
+	mask = (1UL << shift) - 1;
+	page = pte_page(pte);
+	if (page)
+		page += (address & mask) / PAGE_SIZE;
+
+no_page:
+	local_irq_restore(flags);
+	return page;
+}
+
+struct page *
+follow_huge_pmd(struct mm_struct *mm, unsigned long address,
+		pmd_t *pmd, int write)
+{
+	BUG();
+	return NULL;
+}
+
+struct page *
+follow_huge_pud(struct mm_struct *mm, unsigned long address,
+		pud_t *pud, int write)
+{
+	BUG();
+	return NULL;
+}
+
+static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
+				      unsigned long sz)
+{
+	unsigned long __boundary = (addr + sz) & ~(sz-1);
+	return (__boundary - 1 < end - 1) ? __boundary : end;
+}
+
+int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	pte_t *ptep;
+	unsigned long sz = 1UL << hugepd_shift(hugepd);
+	unsigned long next;
+
+	ptep = hugepte_offset(hugepd, addr, pdshift);
+	do {
+		next = hugepte_addr_end(addr, end, sz);
+		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
+			return 0;
+	} while (ptep++, addr = next, addr != end);
+
+	return 1;
+}
+
+#ifdef CONFIG_PPC_MM_SLICES
+unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+					unsigned long len, unsigned long pgoff,
+					unsigned long flags)
+{
+	struct hstate *hstate = hstate_file(file);
+	int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
+
+	return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
+}
+#endif
+
+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+#ifdef CONFIG_PPC_MM_SLICES
+	unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
+
+	return 1UL << mmu_psize_to_shift(psize);
+#else
+	if (!is_vm_hugetlb_page(vma))
+		return PAGE_SIZE;
+
+	return huge_page_size(hstate_vma(vma));
+#endif
+}
+
+static inline bool is_power_of_4(unsigned long x)
+{
+	if (is_power_of_2(x))
+		return (__ilog2(x) % 2) ? false : true;
+	return false;
+}
+
+static int __init add_huge_page_size(unsigned long long size)
+{
+	int shift = __ffs(size);
+	int mmu_psize;
+
+	/* Check that it is a page size supported by the hardware and
+	 * that it fits within pagetable and slice limits. */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	if ((size < PAGE_SIZE) || !is_power_of_4(size))
+		return -EINVAL;
+#else
+	if (!is_power_of_2(size)
+	    || (shift > SLICE_HIGH_SHIFT) || (shift <= PAGE_SHIFT))
+		return -EINVAL;
+#endif
+
+	if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
+		return -EINVAL;
+
+#ifdef CONFIG_SPU_FS_64K_LS
+	/* Disable support for 64K huge pages when 64K SPU local store
+	 * support is enabled as the current implementation conflicts.
+	 */
+	if (shift == PAGE_SHIFT_64K)
+		return -EINVAL;
+#endif /* CONFIG_SPU_FS_64K_LS */
+
+	BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
+
+	/* Return if huge page size has already been setup */
+	if (size_to_hstate(size))
+		return 0;
+
+	hugetlb_add_hstate(shift - PAGE_SHIFT);
+
+	return 0;
+}
+
+static int __init hugepage_setup_sz(char *str)
+{
+	unsigned long long size;
+
+	size = memparse(str, &str);
+
+	if (add_huge_page_size(size) != 0)
+		printk(KERN_WARNING "Invalid huge page size specified(%llu)\n", size);
+
+	return 1;
+}
+__setup("hugepagesz=", hugepage_setup_sz);
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+struct kmem_cache *hugepte_cache;
+static int __init hugetlbpage_init(void)
+{
+	int psize;
+
+	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
+		unsigned shift;
+
+		if (!mmu_psize_defs[psize].shift)
+			continue;
+
+		shift = mmu_psize_to_shift(psize);
+
+		/* Don't treat normal page sizes as huge... */
+		if (shift != PAGE_SHIFT)
+			if (add_huge_page_size(1ULL << shift) < 0)
+				continue;
+	}
+
+	/*
+	 * Create a kmem cache for hugeptes.  The bottom bits in the pte have
+	 * size information encoded in them, so align them to allow this
+	 */
+	hugepte_cache =  kmem_cache_create("hugepte-cache", sizeof(pte_t),
+					   HUGEPD_SHIFT_MASK + 1, 0, NULL);
+	if (hugepte_cache == NULL)
+		panic("%s: Unable to create kmem cache for hugeptes\n",
+		      __func__);
+
+	/* Default hpage size = 4M */
+	if (mmu_psize_defs[MMU_PAGE_4M].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
+	else
+		panic("%s: Unable to set default huge page size\n", __func__);
+
+
+	return 0;
+}
+#else
+static int __init hugetlbpage_init(void)
+{
+	int psize;
+
+	if (!mmu_has_feature(MMU_FTR_16M_PAGE))
+		return -ENODEV;
+
+	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
+		unsigned shift;
+		unsigned pdshift;
+
+		if (!mmu_psize_defs[psize].shift)
+			continue;
+
+		shift = mmu_psize_to_shift(psize);
+
+		if (add_huge_page_size(1ULL << shift) < 0)
+			continue;
+
+		if (shift < PMD_SHIFT)
+			pdshift = PMD_SHIFT;
+		else if (shift < PUD_SHIFT)
+			pdshift = PUD_SHIFT;
+		else
+			pdshift = PGDIR_SHIFT;
+		/*
+		 * if we have pdshift and shift value same, we don't
+		 * use pgt cache for hugepd.
+		 */
+		if (pdshift != shift) {
+			pgtable_cache_add(pdshift - shift, NULL);
+			if (!PGT_CACHE(pdshift - shift))
+				panic("hugetlbpage_init(): could not create "
+				      "pgtable cache for %d bit pagesize\n", shift);
+		}
+	}
+
+	/* Set default large page size. Currently, we pick 16M or 1M
+	 * depending on what is available
+	 */
+	if (mmu_psize_defs[MMU_PAGE_16M].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
+	else if (mmu_psize_defs[MMU_PAGE_1M].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
+
+	return 0;
+}
+#endif
+module_init(hugetlbpage_init);
+
+void flush_dcache_icache_hugepage(struct page *page)
+{
+	int i;
+	void *start;
+
+	BUG_ON(!PageCompound(page));
+
+	for (i = 0; i < (1UL << compound_order(page)); i++) {
+		if (!PageHighMem(page)) {
+			__flush_dcache_icache(page_address(page+i));
+		} else {
+			start = kmap_atomic(page+i);
+			__flush_dcache_icache(start);
+			kunmap_atomic(start);
+		}
+	}
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+/*
+ * We have 4 cases for pgds and pmds:
+ * (1) invalid (all zeroes)
+ * (2) pointer to next table, as normal; bottom 6 bits == 0
+ * (3) leaf pte for huge page, bottom two bits != 00
+ * (4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size of table
+ *
+ * So long as we atomically load page table pointers we are safe against teardown,
+ * we can follow the address down to the the page and take a ref on it.
+ * This function need to be called with interrupts disabled. We use this variant
+ * when we have MSR[EE] = 0 but the paca->soft_enabled = 1
+ */
+
+pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
+				   unsigned *shift)
+{
+	pgd_t pgd, *pgdp;
+	pud_t pud, *pudp;
+	pmd_t pmd, *pmdp;
+	pte_t *ret_pte;
+	hugepd_t *hpdp = NULL;
+	unsigned pdshift = PGDIR_SHIFT;
+
+	if (shift)
+		*shift = 0;
+
+	pgdp = pgdir + pgd_index(ea);
+	pgd  = READ_ONCE(*pgdp);
+	/*
+	 * Always operate on the local stack value. This make sure the
+	 * value don't get updated by a parallel THP split/collapse,
+	 * page fault or a page unmap. The return pte_t * is still not
+	 * stable. So should be checked there for above conditions.
+	 */
+	if (pgd_none(pgd))
+		return NULL;
+	else if (pgd_huge(pgd)) {
+		ret_pte = (pte_t *) pgdp;
+		goto out;
+	} else if (is_hugepd(__hugepd(pgd_val(pgd))))
+		hpdp = (hugepd_t *)&pgd;
+	else {
+		/*
+		 * Even if we end up with an unmap, the pgtable will not
+		 * be freed, because we do an rcu free and here we are
+		 * irq disabled
+		 */
+		pdshift = PUD_SHIFT;
+		pudp = pud_offset(&pgd, ea);
+		pud  = READ_ONCE(*pudp);
+
+		if (pud_none(pud))
+			return NULL;
+		else if (pud_huge(pud)) {
+			ret_pte = (pte_t *) pudp;
+			goto out;
+		} else if (is_hugepd(__hugepd(pud_val(pud))))
+			hpdp = (hugepd_t *)&pud;
+		else {
+			pdshift = PMD_SHIFT;
+			pmdp = pmd_offset(&pud, ea);
+			pmd  = READ_ONCE(*pmdp);
+			/*
+			 * A hugepage collapse is captured by pmd_none, because
+			 * it mark the pmd none and do a hpte invalidate.
+			 *
+			 * We don't worry about pmd_trans_splitting here, The
+			 * caller if it needs to handle the splitting case
+			 * should check for that.
+			 */
+			if (pmd_none(pmd))
+				return NULL;
+
+			if (pmd_huge(pmd) || pmd_large(pmd)) {
+				ret_pte = (pte_t *) pmdp;
+				goto out;
+			} else if (is_hugepd(__hugepd(pmd_val(pmd))))
+				hpdp = (hugepd_t *)&pmd;
+			else
+				return pte_offset_kernel(&pmd, ea);
+		}
+	}
+	if (!hpdp)
+		return NULL;
+
+	ret_pte = hugepte_offset(*hpdp, ea, pdshift);
+	pdshift = hugepd_shift(*hpdp);
+out:
+	if (shift)
+		*shift = pdshift;
+	return ret_pte;
+}
+EXPORT_SYMBOL_GPL(__find_linux_pte_or_hugepte);
+
+int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long mask;
+	unsigned long pte_end;
+	struct page *head, *page, *tail;
+	pte_t pte;
+	int refs;
+
+	pte_end = (addr + sz) & ~(sz-1);
+	if (pte_end < end)
+		end = pte_end;
+
+	pte = READ_ONCE(*ptep);
+	mask = _PAGE_PRESENT | _PAGE_USER;
+	if (write)
+		mask |= _PAGE_RW;
+
+	if ((pte_val(pte) & mask) != mask)
+		return 0;
+
+	/* hugepages are never "special" */
+	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+
+	refs = 0;
+	head = pte_page(pte);
+
+	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
+	tail = page;
+	do {
+		VM_BUG_ON(compound_head(page) != head);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+		/* Could be optimized better */
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	/*
+	 * Any tail page need their mapcount reference taken before we
+	 * return.
+	 */
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
+	}
+
+	return 1;
+}