2 * This file contains ioremap and related functions for 64-bit machines.
4 * Derived from arch/ppc64/mm/init.c
5 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
7 * Modifications by Paul Mackerras (PowerMac) (paulus@samba.org)
8 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
9 * Copyright (C) 1996 Paul Mackerras
11 * Derived from "arch/i386/mm/init.c"
12 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
14 * Dave Engebretsen <engebret@us.ibm.com>
15 * Rework for PPC64 port.
17 * This program is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public License
19 * as published by the Free Software Foundation; either version
20 * 2 of the License, or (at your option) any later version.
24 #include <linux/signal.h>
25 #include <linux/sched.h>
26 #include <linux/kernel.h>
27 #include <linux/errno.h>
28 #include <linux/string.h>
29 #include <linux/export.h>
30 #include <linux/types.h>
31 #include <linux/mman.h>
33 #include <linux/swap.h>
34 #include <linux/stddef.h>
35 #include <linux/vmalloc.h>
36 #include <linux/memblock.h>
37 #include <linux/slab.h>
38 #include <linux/hugetlb.h>
40 #include <asm/pgalloc.h>
44 #include <asm/mmu_context.h>
45 #include <asm/pgtable.h>
48 #include <asm/machdep.h>
50 #include <asm/processor.h>
51 #include <asm/cputable.h>
52 #include <asm/sections.h>
53 #include <asm/firmware.h>
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/thp.h>
61 /* Some sanity checking */
62 #if TASK_SIZE_USER64 > PGTABLE_RANGE
63 #error TASK_SIZE_USER64 exceeds pagetable range
66 #ifdef CONFIG_PPC_STD_MMU_64
67 #if TASK_SIZE_USER64 > (1UL << (ESID_BITS + SID_SHIFT))
68 #error TASK_SIZE_USER64 exceeds user VSID range
72 unsigned long ioremap_bot = IOREMAP_BASE;
74 #ifdef CONFIG_PPC_MMU_NOHASH
75 static __ref void *early_alloc_pgtable(unsigned long size)
79 pt = __va(memblock_alloc_base(size, size, __pa(MAX_DMA_ADDRESS)));
84 #endif /* CONFIG_PPC_MMU_NOHASH */
87 * map_kernel_page currently only called by __ioremap
88 * map_kernel_page adds an entry to the ioremap page table
89 * and adds an entry to the HPT, possibly bolting it
91 int map_kernel_page(unsigned long ea, unsigned long pa, unsigned long flags)
98 if (slab_is_available()) {
99 pgdp = pgd_offset_k(ea);
100 pudp = pud_alloc(&init_mm, pgdp, ea);
103 pmdp = pmd_alloc(&init_mm, pudp, ea);
106 ptep = pte_alloc_kernel(pmdp, ea);
109 set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
112 #ifdef CONFIG_PPC_MMU_NOHASH
113 pgdp = pgd_offset_k(ea);
114 #ifdef PUD_TABLE_SIZE
115 if (pgd_none(*pgdp)) {
116 pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
117 BUG_ON(pudp == NULL);
118 pgd_populate(&init_mm, pgdp, pudp);
120 #endif /* PUD_TABLE_SIZE */
121 pudp = pud_offset(pgdp, ea);
122 if (pud_none(*pudp)) {
123 pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
124 BUG_ON(pmdp == NULL);
125 pud_populate(&init_mm, pudp, pmdp);
127 pmdp = pmd_offset(pudp, ea);
128 if (!pmd_present(*pmdp)) {
129 ptep = early_alloc_pgtable(PAGE_SIZE);
130 BUG_ON(ptep == NULL);
131 pmd_populate_kernel(&init_mm, pmdp, ptep);
133 ptep = pte_offset_kernel(pmdp, ea);
134 set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
136 #else /* CONFIG_PPC_MMU_NOHASH */
138 * If the mm subsystem is not fully up, we cannot create a
139 * linux page table entry for this mapping. Simply bolt an
140 * entry in the hardware page table.
143 if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, flags,
144 mmu_io_psize, mmu_kernel_ssize)) {
145 printk(KERN_ERR "Failed to do bolted mapping IO "
146 "memory at %016lx !\n", pa);
149 #endif /* !CONFIG_PPC_MMU_NOHASH */
158 * __ioremap_at - Low level function to establish the page tables
161 void __iomem * __ioremap_at(phys_addr_t pa, void *ea, unsigned long size,
166 /* Make sure we have the base flags */
167 if ((flags & _PAGE_PRESENT) == 0)
168 flags |= pgprot_val(PAGE_KERNEL);
170 /* Non-cacheable page cannot be coherent */
171 if (flags & _PAGE_NO_CACHE)
172 flags &= ~_PAGE_COHERENT;
174 /* We don't support the 4K PFN hack with ioremap */
175 if (flags & _PAGE_4K_PFN)
178 WARN_ON(pa & ~PAGE_MASK);
179 WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
180 WARN_ON(size & ~PAGE_MASK);
182 for (i = 0; i < size; i += PAGE_SIZE)
183 if (map_kernel_page((unsigned long)ea+i, pa+i, flags))
186 return (void __iomem *)ea;
190 * __iounmap_from - Low level function to tear down the page tables
191 * for an IO mapping. This is used for mappings that
192 * are manipulated manually, like partial unmapping of
193 * PCI IOs or ISA space.
195 void __iounmap_at(void *ea, unsigned long size)
197 WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
198 WARN_ON(size & ~PAGE_MASK);
200 unmap_kernel_range((unsigned long)ea, size);
203 void __iomem * __ioremap_caller(phys_addr_t addr, unsigned long size,
204 unsigned long flags, void *caller)
206 phys_addr_t paligned;
210 * Choose an address to map it to.
211 * Once the imalloc system is running, we use it.
212 * Before that, we map using addresses going
213 * up from ioremap_bot. imalloc will use
214 * the addresses from ioremap_bot through
218 paligned = addr & PAGE_MASK;
219 size = PAGE_ALIGN(addr + size) - paligned;
221 if ((size == 0) || (paligned == 0))
224 if (slab_is_available()) {
225 struct vm_struct *area;
227 area = __get_vm_area_caller(size, VM_IOREMAP,
228 ioremap_bot, IOREMAP_END,
233 area->phys_addr = paligned;
234 ret = __ioremap_at(paligned, area->addr, size, flags);
238 ret = __ioremap_at(paligned, (void *)ioremap_bot, size, flags);
244 ret += addr & ~PAGE_MASK;
248 void __iomem * __ioremap(phys_addr_t addr, unsigned long size,
251 return __ioremap_caller(addr, size, flags, __builtin_return_address(0));
254 void __iomem * ioremap(phys_addr_t addr, unsigned long size)
256 unsigned long flags = _PAGE_NO_CACHE | _PAGE_GUARDED;
257 void *caller = __builtin_return_address(0);
260 return ppc_md.ioremap(addr, size, flags, caller);
261 return __ioremap_caller(addr, size, flags, caller);
264 void __iomem * ioremap_wc(phys_addr_t addr, unsigned long size)
266 unsigned long flags = _PAGE_NO_CACHE;
267 void *caller = __builtin_return_address(0);
270 return ppc_md.ioremap(addr, size, flags, caller);
271 return __ioremap_caller(addr, size, flags, caller);
274 void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
277 void *caller = __builtin_return_address(0);
279 /* writeable implies dirty for kernel addresses */
280 if (flags & _PAGE_WRITE)
281 flags |= _PAGE_DIRTY;
283 /* we don't want to let _PAGE_EXEC leak out */
284 flags &= ~_PAGE_EXEC;
286 * Force kernel mapping.
288 #if defined(CONFIG_PPC_BOOK3S_64)
289 flags |= _PAGE_PRIVILEGED;
291 flags &= ~_PAGE_USER;
296 /* _PAGE_USER contains _PAGE_BAP_SR on BookE using the new PTE format
297 * which means that we just cleared supervisor access... oops ;-) This
300 flags |= _PAGE_BAP_SR;
304 return ppc_md.ioremap(addr, size, flags, caller);
305 return __ioremap_caller(addr, size, flags, caller);
310 * Unmap an IO region and remove it from imalloc'd list.
311 * Access to IO memory should be serialized by driver.
313 void __iounmap(volatile void __iomem *token)
317 if (!slab_is_available())
320 addr = (void *) ((unsigned long __force)
321 PCI_FIX_ADDR(token) & PAGE_MASK);
322 if ((unsigned long)addr < ioremap_bot) {
323 printk(KERN_WARNING "Attempt to iounmap early bolted mapping"
330 void iounmap(volatile void __iomem *token)
333 ppc_md.iounmap(token);
338 EXPORT_SYMBOL(ioremap);
339 EXPORT_SYMBOL(ioremap_wc);
340 EXPORT_SYMBOL(ioremap_prot);
341 EXPORT_SYMBOL(__ioremap);
342 EXPORT_SYMBOL(__ioremap_at);
343 EXPORT_SYMBOL(iounmap);
344 EXPORT_SYMBOL(__iounmap);
345 EXPORT_SYMBOL(__iounmap_at);
347 #ifndef __PAGETABLE_PUD_FOLDED
348 /* 4 level page table */
349 struct page *pgd_page(pgd_t pgd)
352 return pte_page(pgd_pte(pgd));
353 return virt_to_page(pgd_page_vaddr(pgd));
357 struct page *pud_page(pud_t pud)
360 return pte_page(pud_pte(pud));
361 return virt_to_page(pud_page_vaddr(pud));
365 * For hugepage we have pfn in the pmd, we use PTE_RPN_SHIFT bits for flags
366 * For PTE page, we have a PTE_FRAG_SIZE (4K) aligned virtual address.
368 struct page *pmd_page(pmd_t pmd)
370 if (pmd_trans_huge(pmd) || pmd_huge(pmd))
371 return pte_page(pmd_pte(pmd));
372 return virt_to_page(pmd_page_vaddr(pmd));
375 #ifdef CONFIG_PPC_64K_PAGES
376 static pte_t *get_from_cache(struct mm_struct *mm)
378 void *pte_frag, *ret;
380 spin_lock(&mm->page_table_lock);
381 ret = mm->context.pte_frag;
383 pte_frag = ret + PTE_FRAG_SIZE;
385 * If we have taken up all the fragments mark PTE page NULL
387 if (((unsigned long)pte_frag & ~PAGE_MASK) == 0)
389 mm->context.pte_frag = pte_frag;
391 spin_unlock(&mm->page_table_lock);
395 static pte_t *__alloc_for_cache(struct mm_struct *mm, int kernel)
398 struct page *page = alloc_page(GFP_KERNEL | __GFP_NOTRACK |
399 __GFP_REPEAT | __GFP_ZERO);
402 if (!kernel && !pgtable_page_ctor(page)) {
407 ret = page_address(page);
408 spin_lock(&mm->page_table_lock);
410 * If we find pgtable_page set, we return
411 * the allocated page with single fragement
414 if (likely(!mm->context.pte_frag)) {
415 set_page_count(page, PTE_FRAG_NR);
416 mm->context.pte_frag = ret + PTE_FRAG_SIZE;
418 spin_unlock(&mm->page_table_lock);
423 pte_t *page_table_alloc(struct mm_struct *mm, unsigned long vmaddr, int kernel)
427 pte = get_from_cache(mm);
431 return __alloc_for_cache(mm, kernel);
434 void page_table_free(struct mm_struct *mm, unsigned long *table, int kernel)
436 struct page *page = virt_to_page(table);
437 if (put_page_testzero(page)) {
439 pgtable_page_dtor(page);
440 free_hot_cold_page(page, 0);
445 static void page_table_free_rcu(void *table)
447 struct page *page = virt_to_page(table);
448 if (put_page_testzero(page)) {
449 pgtable_page_dtor(page);
450 free_hot_cold_page(page, 0);
454 void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
456 unsigned long pgf = (unsigned long)table;
458 BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
460 tlb_remove_table(tlb, (void *)pgf);
463 void __tlb_remove_table(void *_table)
465 void *table = (void *)((unsigned long)_table & ~MAX_PGTABLE_INDEX_SIZE);
466 unsigned shift = (unsigned long)_table & MAX_PGTABLE_INDEX_SIZE;
469 /* PTE page needs special handling */
470 page_table_free_rcu(table);
472 BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
473 kmem_cache_free(PGT_CACHE(shift), table);
477 void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
480 /* PTE page needs special handling */
481 struct page *page = virt_to_page(table);
482 if (put_page_testzero(page)) {
483 pgtable_page_dtor(page);
484 free_hot_cold_page(page, 0);
487 BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
488 kmem_cache_free(PGT_CACHE(shift), table);
492 #endif /* CONFIG_PPC_64K_PAGES */
494 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
497 * This is called when relaxing access to a hugepage. It's also called in the page
498 * fault path when we don't hit any of the major fault cases, ie, a minor
499 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
500 * handled those two for us, we additionally deal with missing execute
501 * permission here on some processors
503 int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
504 pmd_t *pmdp, pmd_t entry, int dirty)
507 #ifdef CONFIG_DEBUG_VM
508 WARN_ON(!pmd_trans_huge(*pmdp));
509 assert_spin_locked(&vma->vm_mm->page_table_lock);
511 changed = !pmd_same(*(pmdp), entry);
513 __ptep_set_access_flags(pmdp_ptep(pmdp), pmd_pte(entry));
515 * Since we are not supporting SW TLB systems, we don't
516 * have any thing similar to flush_tlb_page_nohash()
522 unsigned long pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
523 pmd_t *pmdp, unsigned long clr,
530 #ifdef CONFIG_DEBUG_VM
531 WARN_ON(!pmd_trans_huge(*pmdp));
532 assert_spin_locked(&mm->page_table_lock);
535 __asm__ __volatile__(
543 : "=&r" (old_be), "=&r" (tmp), "=m" (*pmdp)
544 : "r" (pmdp), "r" (cpu_to_be64(clr)), "m" (*pmdp),
545 "r" (cpu_to_be64(_PAGE_BUSY)), "r" (cpu_to_be64(set))
548 old = be64_to_cpu(old_be);
550 trace_hugepage_update(addr, old, clr, set);
551 if (old & _PAGE_HASHPTE)
552 hpte_do_hugepage_flush(mm, addr, pmdp, old);
556 pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
561 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
562 VM_BUG_ON(pmd_trans_huge(*pmdp));
567 * Wait for all pending hash_page to finish. This is needed
568 * in case of subpage collapse. When we collapse normal pages
569 * to hugepage, we first clear the pmd, then invalidate all
570 * the PTE entries. The assumption here is that any low level
571 * page fault will see a none pmd and take the slow path that
572 * will wait on mmap_sem. But we could very well be in a
573 * hash_page with local ptep pointer value. Such a hash page
574 * can result in adding new HPTE entries for normal subpages.
575 * That means we could be modifying the page content as we
576 * copy them to a huge page. So wait for parallel hash_page
577 * to finish before invalidating HPTE entries. We can do this
578 * by sending an IPI to all the cpus and executing a dummy
581 kick_all_cpus_sync();
583 * Now invalidate the hpte entries in the range
584 * covered by pmd. This make sure we take a
585 * fault and will find the pmd as none, which will
586 * result in a major fault which takes mmap_sem and
587 * hence wait for collapse to complete. Without this
588 * the __collapse_huge_page_copy can result in copying
591 flush_tlb_pmd_range(vma->vm_mm, &pmd, address);
595 int pmdp_test_and_clear_young(struct vm_area_struct *vma,
596 unsigned long address, pmd_t *pmdp)
598 return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
602 * We currently remove entries from the hashtable regardless of whether
603 * the entry was young or dirty. The generic routines only flush if the
604 * entry was young or dirty which is not good enough.
606 * We should be more intelligent about this but for the moment we override
607 * these functions and force a tlb flush unconditionally
609 int pmdp_clear_flush_young(struct vm_area_struct *vma,
610 unsigned long address, pmd_t *pmdp)
612 return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
616 * We want to put the pgtable in pmd and use pgtable for tracking
617 * the base page size hptes
619 void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
622 pgtable_t *pgtable_slot;
623 assert_spin_locked(&mm->page_table_lock);
625 * we store the pgtable in the second half of PMD
627 pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
628 *pgtable_slot = pgtable;
630 * expose the deposited pgtable to other cpus.
631 * before we set the hugepage PTE at pmd level
632 * hash fault code looks at the deposted pgtable
633 * to store hash index values.
638 pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
641 pgtable_t *pgtable_slot;
643 assert_spin_locked(&mm->page_table_lock);
644 pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
645 pgtable = *pgtable_slot;
647 * Once we withdraw, mark the entry NULL.
649 *pgtable_slot = NULL;
651 * We store HPTE information in the deposited PTE fragment.
652 * zero out the content on withdraw.
654 memset(pgtable, 0, PTE_FRAG_SIZE);
658 void pmdp_huge_split_prepare(struct vm_area_struct *vma,
659 unsigned long address, pmd_t *pmdp)
661 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
662 VM_BUG_ON(REGION_ID(address) != USER_REGION_ID);
665 * We can't mark the pmd none here, because that will cause a race
666 * against exit_mmap. We need to continue mark pmd TRANS HUGE, while
667 * we spilt, but at the same time we wan't rest of the ppc64 code
668 * not to insert hash pte on this, because we will be modifying
669 * the deposited pgtable in the caller of this function. Hence
670 * clear the _PAGE_USER so that we move the fault handling to
671 * higher level function and that will serialize against ptl.
672 * We need to flush existing hash pte entries here even though,
673 * the translation is still valid, because we will withdraw
674 * pgtable_t after this.
676 pmd_hugepage_update(vma->vm_mm, address, pmdp, 0, _PAGE_PRIVILEGED);
681 * set a new huge pmd. We should not be called for updating
682 * an existing pmd entry. That should go via pmd_hugepage_update.
684 void set_pmd_at(struct mm_struct *mm, unsigned long addr,
685 pmd_t *pmdp, pmd_t pmd)
687 #ifdef CONFIG_DEBUG_VM
688 WARN_ON(pte_present(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));
689 assert_spin_locked(&mm->page_table_lock);
690 WARN_ON(!pmd_trans_huge(pmd));
692 trace_hugepage_set_pmd(addr, pmd_val(pmd));
693 return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
697 * We use this to invalidate a pmdp entry before switching from a
698 * hugepte to regular pmd entry.
700 void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
703 pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, 0);
706 * This ensures that generic code that rely on IRQ disabling
707 * to prevent a parallel THP split work as expected.
709 kick_all_cpus_sync();
713 * A linux hugepage PMD was changed and the corresponding hash table entries
714 * neesd to be flushed.
716 void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr,
717 pmd_t *pmdp, unsigned long old_pmd)
722 unsigned long flags = 0;
723 const struct cpumask *tmp;
725 /* get the base page size,vsid and segment size */
726 #ifdef CONFIG_DEBUG_VM
727 psize = get_slice_psize(mm, addr);
728 BUG_ON(psize == MMU_PAGE_16M);
730 if (old_pmd & _PAGE_COMBO)
733 psize = MMU_PAGE_64K;
735 if (!is_kernel_addr(addr)) {
736 ssize = user_segment_size(addr);
737 vsid = get_vsid(mm->context.id, addr, ssize);
740 vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
741 ssize = mmu_kernel_ssize;
744 tmp = cpumask_of(smp_processor_id());
745 if (cpumask_equal(mm_cpumask(mm), tmp))
746 flags |= HPTE_LOCAL_UPDATE;
748 return flush_hash_hugepage(vsid, addr, pmdp, psize, ssize, flags);
751 static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
753 return __pmd(pmd_val(pmd) | pgprot_val(pgprot));
756 pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
760 pmdv = (pfn << PTE_RPN_SHIFT) & PTE_RPN_MASK;
761 return pmd_set_protbits(__pmd(pmdv), pgprot);
764 pmd_t mk_pmd(struct page *page, pgprot_t pgprot)
766 return pfn_pmd(page_to_pfn(page), pgprot);
769 pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
774 pmdv &= _HPAGE_CHG_MASK;
775 return pmd_set_protbits(__pmd(pmdv), newprot);
779 * This is called at the end of handling a user page fault, when the
780 * fault has been handled by updating a HUGE PMD entry in the linux page tables.
781 * We use it to preload an HPTE into the hash table corresponding to
782 * the updated linux HUGE PMD entry.
784 void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
790 pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
791 unsigned long addr, pmd_t *pmdp)
796 pgtable_t *pgtable_slot;
798 old = pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0);
799 old_pmd = __pmd(old);
801 * We have pmd == none and we are holding page_table_lock.
802 * So we can safely go and clear the pgtable hash
805 pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
806 pgtable = *pgtable_slot;
808 * Let's zero out old valid and hash index details
809 * hash fault look at them.
811 memset(pgtable, 0, PTE_FRAG_SIZE);
813 * Serialize against find_linux_pte_or_hugepte which does lock-less
814 * lookup in page tables with local interrupts disabled. For huge pages
815 * it casts pmd_t to pte_t. Since format of pte_t is different from
816 * pmd_t we want to prevent transit from pmd pointing to page table
817 * to pmd pointing to huge page (and back) while interrupts are disabled.
818 * We clear pmd to possibly replace it with page table pointer in
819 * different code paths. So make sure we wait for the parallel
820 * find_linux_pte_or_hugepage to finish.
822 kick_all_cpus_sync();
826 int has_transparent_hugepage(void)
829 BUILD_BUG_ON_MSG((PMD_SHIFT - PAGE_SHIFT) >= MAX_ORDER,
830 "hugepages can't be allocated by the buddy allocator");
832 BUILD_BUG_ON_MSG((PMD_SHIFT - PAGE_SHIFT) < 2,
833 "We need more than 2 pages to do deferred thp split");
835 if (!mmu_has_feature(MMU_FTR_16M_PAGE))
838 * We support THP only if PMD_SIZE is 16MB.
840 if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT)
843 * We need to make sure that we support 16MB hugepage in a segement
844 * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE
848 * If we have 64K HPTE, we will be using that by default
850 if (mmu_psize_defs[MMU_PAGE_64K].shift &&
851 (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1))
854 * Ok we only have 4K HPTE
856 if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1)
861 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */