Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 919 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
new file mode 100644
index 000000000..cef0b7ee1
--- /dev/null
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -0,0 +1,919 @@
+/*
+ * 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 <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/kmemleak.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+#include <asm/setup.h>
+#include <asm/hugetlb.h>
+#include <asm/pte-walk.h>
+
+
+#ifdef CONFIG_HUGETLB_PAGE
+
+#define PAGE_SHIFT_64K	16
+#define PAGE_SHIFT_512K	19
+#define PAGE_SHIFT_8M	23
+#define PAGE_SHIFT_16M	24
+#define PAGE_SHIFT_16G	34
+
+bool hugetlb_disabled = false;
+
+unsigned int HPAGE_SHIFT;
+EXPORT_SYMBOL(HPAGE_SHIFT);
+
+#define hugepd_none(hpd)	(hpd_val(hpd) == 0)
+
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
+{
+	/*
+	 * Only called for hugetlbfs pages, hence can ignore THP and the
+	 * irq disabled walk.
+	 */
+	return __find_linux_pte(mm->pgd, addr, NULL, NULL);
+}
+
+static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
+			   unsigned long address, unsigned int pdshift,
+			   unsigned int pshift, spinlock_t *ptl)
+{
+	struct kmem_cache *cachep;
+	pte_t *new;
+	int i;
+	int num_hugepd;
+
+	if (pshift >= pdshift) {
+		cachep = hugepte_cache;
+		num_hugepd = 1 << (pshift - pdshift);
+	} else {
+		cachep = PGT_CACHE(pdshift - pshift);
+		num_hugepd = 1;
+	}
+
+	new = kmem_cache_zalloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
+
+	BUG_ON(pshift > HUGEPD_SHIFT_MASK);
+	BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
+
+	if (! new)
+		return -ENOMEM;
+
+	/*
+	 * Make sure other cpus find the hugepd set only after a
+	 * properly initialized page table is visible to them.
+	 * For more details look for comment in __pte_alloc().
+	 */
+	smp_wmb();
+
+	spin_lock(ptl);
+	/*
+	 * 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 {
+#ifdef CONFIG_PPC_BOOK3S_64
+			*hpdp = __hugepd(__pa(new) |
+					 (shift_to_mmu_psize(pshift) << 2));
+#elif defined(CONFIG_PPC_8xx)
+			*hpdp = __hugepd(__pa(new) | _PMD_USER |
+					 (pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
+					  _PMD_PAGE_512K) | _PMD_PRESENT);
+#else
+			/* We use the old format for PPC_FSL_BOOK3E */
+			*hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
+#endif
+		}
+	}
+	/* 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 = __hugepd(0);
+		kmem_cache_free(cachep, new);
+	} else {
+		kmemleak_ignore(new);
+	}
+	spin_unlock(ptl);
+	return 0;
+}
+
+/*
+ * 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;
+	spinlock_t *ptl;
+
+	addr &= ~(sz-1);
+	pg = pgd_offset(mm, addr);
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	if (pshift == PGDIR_SHIFT)
+		/* 16GB huge page */
+		return (pte_t *) pg;
+	else if (pshift > PUD_SHIFT) {
+		/*
+		 * We need to use hugepd table
+		 */
+		ptl = &mm->page_table_lock;
+		hpdp = (hugepd_t *)pg;
+	} else {
+		pdshift = PUD_SHIFT;
+		pu = pud_alloc(mm, pg, addr);
+		if (!pu)
+			return NULL;
+		if (pshift == PUD_SHIFT)
+			return (pte_t *)pu;
+		else if (pshift > PMD_SHIFT) {
+			ptl = pud_lockptr(mm, pu);
+			hpdp = (hugepd_t *)pu;
+		} else {
+			pdshift = PMD_SHIFT;
+			pm = pmd_alloc(mm, pu, addr);
+			if (!pm)
+				return NULL;
+			if (pshift == PMD_SHIFT)
+				/* 16MB hugepage */
+				return (pte_t *)pm;
+			else {
+				ptl = pmd_lockptr(mm, pm);
+				hpdp = (hugepd_t *)pm;
+			}
+		}
+	}
+#else
+	if (pshift >= PGDIR_SHIFT) {
+		ptl = &mm->page_table_lock;
+		hpdp = (hugepd_t *)pg;
+	} else {
+		pdshift = PUD_SHIFT;
+		pu = pud_alloc(mm, pg, addr);
+		if (!pu)
+			return NULL;
+		if (pshift >= PUD_SHIFT) {
+			ptl = pud_lockptr(mm, pu);
+			hpdp = (hugepd_t *)pu;
+		} else {
+			pdshift = PMD_SHIFT;
+			pm = pmd_alloc(mm, pu, addr);
+			if (!pm)
+				return NULL;
+			ptl = pmd_lockptr(mm, pm);
+			hpdp = (hugepd_t *)pm;
+		}
+	}
+#endif
+	if (!hpdp)
+		return NULL;
+
+	BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
+
+	if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr,
+						  pdshift, pshift, ptl))
+		return NULL;
+
+	return hugepte_offset(*hpdp, addr, pdshift);
+}
+
+#ifdef CONFIG_PPC_BOOK3S_64
+/*
+ * Tracks gpages after the device tree is scanned and before the
+ * huge_boot_pages list is ready on pseries.
+ */
+#define MAX_NUMBER_GPAGES	1024
+__initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
+__initdata static unsigned nr_gpages;
+
+/*
+ * Build list of addresses of gigantic pages.  This function is used in early
+ * boot before the buddy allocator is setup.
+ */
+void __init pseries_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;
+	}
+}
+
+int __init pseries_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 __init alloc_bootmem_huge_page(struct hstate *h)
+{
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
+		return pseries_alloc_bootmem_huge_page(h);
+#endif
+	return __alloc_bootmem_huge_page(h);
+}
+
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
+#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 = &get_cpu_var(hugepd_freelist_cur);
+
+	if (atomic_read(&tlb->mm->mm_users) < 2 ||
+	    mm_is_thread_local(tlb->mm)) {
+		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);
+}
+#else
+static inline void hugepd_free(struct mmu_gather *tlb, void *hugepte) {}
+#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;
+	unsigned int shift = hugepd_shift(*hpdp);
+
+	/* Note: On fsl the hpdp may be the first of several */
+	if (shift > pdshift)
+		num_hugepd = 1 << (shift - pdshift);
+
+	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 = __hugepd(0);
+
+	if (shift >= pdshift)
+		hugepd_free(tlb, hugepte);
+	else
+		pgtable_free_tlb(tlb, hugepte,
+				 get_hugepd_cache_index(pdshift - shift));
+}
+
+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 {
+		unsigned long more;
+
+		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;
+		}
+		/*
+		 * 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.
+		 */
+		more = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
+		if (more > next)
+			next = more;
+
+		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 {
+			unsigned long more;
+			/*
+			 * 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.
+			 */
+			more = addr + (1 << hugepd_shift(*(hugepd_t *)pud));
+			if (more > next)
+				next = more;
+
+			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);
+	mm_dec_nr_puds(tlb->mm);
+}
+
+/*
+ * 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 {
+			unsigned long more;
+			/*
+			 * 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.
+			 */
+			more = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
+			if (more > next)
+				next = more;
+
+			free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
+					  addr, next, floor, ceiling);
+		}
+	} while (addr = next, addr != end);
+}
+
+struct page *follow_huge_pd(struct vm_area_struct *vma,
+			    unsigned long address, hugepd_t hpd,
+			    int flags, int pdshift)
+{
+	pte_t *ptep;
+	spinlock_t *ptl;
+	struct page *page = NULL;
+	unsigned long mask;
+	int shift = hugepd_shift(hpd);
+	struct mm_struct *mm = vma->vm_mm;
+
+retry:
+	/*
+	 * hugepage directory entries are protected by mm->page_table_lock
+	 * Use this instead of huge_pte_lockptr
+	 */
+	ptl = &mm->page_table_lock;
+	spin_lock(ptl);
+
+	ptep = hugepte_offset(hpd, address, pdshift);
+	if (pte_present(*ptep)) {
+		mask = (1UL << shift) - 1;
+		page = pte_page(*ptep);
+		page += ((address & mask) >> PAGE_SHIFT);
+		if (flags & FOLL_GET)
+			get_page(page);
+	} else {
+		if (is_hugetlb_entry_migration(*ptep)) {
+			spin_unlock(ptl);
+			__migration_entry_wait(mm, ptep, ptl);
+			goto retry;
+		}
+	}
+	spin_unlock(ptl);
+	return page;
+}
+
+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));
+
+#ifdef CONFIG_PPC_RADIX_MMU
+	if (radix_enabled())
+		return radix__hugetlb_get_unmapped_area(file, addr, len,
+						       pgoff, flags);
+#endif
+	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
+	/* With radix we don't use slice, so derive it from vma*/
+	if (!radix_enabled()) {
+		unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
+
+		return 1UL << mmu_psize_to_shift(psize);
+	}
+#endif
+	return vma_kernel_pagesize(vma);
+}
+
+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. */
+	if (size <= PAGE_SIZE)
+		return -EINVAL;
+#if defined(CONFIG_PPC_FSL_BOOK3E)
+	if (!is_power_of_4(size))
+		return -EINVAL;
+#elif !defined(CONFIG_PPC_8xx)
+	if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
+		return -EINVAL;
+#endif
+
+	if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
+		return -EINVAL;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	/*
+	 * We need to make sure that for different page sizes reported by
+	 * firmware we only add hugetlb support for page sizes that can be
+	 * supported by linux page table layout.
+	 * For now we have
+	 * Radix: 2M and 1G
+	 * Hash: 16M and 16G
+	 */
+	if (radix_enabled()) {
+		if (mmu_psize != MMU_PAGE_2M && mmu_psize != MMU_PAGE_1G)
+			return -EINVAL;
+	} else {
+		if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
+			return -EINVAL;
+	}
+#endif
+
+	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) {
+		hugetlb_bad_size();
+		pr_err("Invalid huge page size specified(%llu)\n", size);
+	}
+
+	return 1;
+}
+__setup("hugepagesz=", hugepage_setup_sz);
+
+struct kmem_cache *hugepte_cache;
+static int __init hugetlbpage_init(void)
+{
+	int psize;
+
+	if (hugetlb_disabled) {
+		pr_info("HugeTLB support is disabled!\n");
+		return 0;
+	}
+
+#if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
+	if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
+		return -ENODEV;
+#endif
+	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);
+
+#ifdef CONFIG_PPC_BOOK3S_64
+		if (shift > PGDIR_SHIFT)
+			continue;
+		else if (shift > PUD_SHIFT)
+			pdshift = PGDIR_SHIFT;
+		else if (shift > PMD_SHIFT)
+			pdshift = PUD_SHIFT;
+		else
+			pdshift = PMD_SHIFT;
+#else
+		if (shift < PUD_SHIFT)
+			pdshift = PMD_SHIFT;
+		else if (shift < PGDIR_SHIFT)
+			pdshift = PUD_SHIFT;
+		else
+			pdshift = PGDIR_SHIFT;
+#endif
+
+		if (add_huge_page_size(1ULL << shift) < 0)
+			continue;
+		/*
+		 * 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 defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
+		else if (!hugepte_cache) {
+			/*
+			 * 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__);
+
+		}
+#endif
+	}
+
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
+	/* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
+	if (mmu_psize_defs[MMU_PAGE_4M].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
+	else if (mmu_psize_defs[MMU_PAGE_512K].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
+#else
+	/* 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;
+	else if (mmu_psize_defs[MMU_PAGE_2M].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
+#endif
+	return 0;
+}
+
+arch_initcall(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 _PAGE_PTE set
+ * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] 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->irq_soft_mask = IRQS_ENABLED
+ */
+pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
+			bool *is_thp, unsigned *hpage_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 (hpage_shift)
+		*hpage_shift = 0;
+
+	if (is_thp)
+		*is_thp = false;
+
+	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.
+			 */
+			if (pmd_none(pmd))
+				return NULL;
+
+			if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
+				if (is_thp)
+					*is_thp = true;
+				ret_pte = (pte_t *) pmdp;
+				goto out;
+			}
+
+			if (pmd_huge(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 (hpage_shift)
+		*hpage_shift = pdshift;
+	return ret_pte;
+}
+EXPORT_SYMBOL_GPL(__find_linux_pte);
+
+int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long pte_end;
+	struct page *head, *page;
+	pte_t pte;
+	int refs;
+
+	pte_end = (addr + sz) & ~(sz-1);
+	if (pte_end < end)
+		end = pte_end;
+
+	pte = READ_ONCE(*ptep);
+
+	if (!pte_access_permitted(pte, write))
+		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);
+	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;
+	}
+
+	return 1;
+}