arch/powerpc/mm/pgtable-book3s64.c

   1 /*
   2  * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/mm_types.h>
  12 #include <misc/cxl-base.h>
  13
  14 #include <asm/pgalloc.h>
  15 #include <asm/tlb.h>
  16
  17 #include "mmu_decl.h"
  18 #include <trace/events/thp.h>
  19
  20 int (*register_process_table)(unsigned long base, unsigned long page_size,
  21                               unsigned long tbl_size);
  22
  23 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  24 /*
  25  * This is called when relaxing access to a hugepage. It's also called in the page
  26  * fault path when we don't hit any of the major fault cases, ie, a minor
  27  * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
  28  * handled those two for us, we additionally deal with missing execute
  29  * permission here on some processors
  30  */
  31 int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
  32                           pmd_t *pmdp, pmd_t entry, int dirty)
  33 {
  34         int changed;
  35 #ifdef CONFIG_DEBUG_VM
  36         WARN_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
  37         assert_spin_locked(&vma->vm_mm->page_table_lock);
  38 #endif
  39         changed = !pmd_same(*(pmdp), entry);
  40         if (changed) {
  41                 __ptep_set_access_flags(vma->vm_mm, pmdp_ptep(pmdp),
  42                                         pmd_pte(entry), address);
  43                 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
  44         }
  45         return changed;
  46 }
  47
  48 int pmdp_test_and_clear_young(struct vm_area_struct *vma,
  49                               unsigned long address, pmd_t *pmdp)
  50 {
  51         return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
  52 }
  53 /*
  54  * set a new huge pmd. We should not be called for updating
  55  * an existing pmd entry. That should go via pmd_hugepage_update.
  56  */
  57 void set_pmd_at(struct mm_struct *mm, unsigned long addr,
  58                 pmd_t *pmdp, pmd_t pmd)
  59 {
  60 #ifdef CONFIG_DEBUG_VM
  61         WARN_ON(pte_present(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));
  62         assert_spin_locked(&mm->page_table_lock);
  63         WARN_ON(!(pmd_trans_huge(pmd) || pmd_devmap(pmd)));
  64 #endif
  65         trace_hugepage_set_pmd(addr, pmd_val(pmd));
  66         return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
  67 }
  68
  69 static void do_nothing(void *unused)
  70 {
  71
  72 }
  73 /*
  74  * Serialize against find_current_mm_pte which does lock-less
  75  * lookup in page tables with local interrupts disabled. For huge pages
  76  * it casts pmd_t to pte_t. Since format of pte_t is different from
  77  * pmd_t we want to prevent transit from pmd pointing to page table
  78  * to pmd pointing to huge page (and back) while interrupts are disabled.
  79  * We clear pmd to possibly replace it with page table pointer in
  80  * different code paths. So make sure we wait for the parallel
  81  * find_current_mm_pte to finish.
  82  */
  83 void serialize_against_pte_lookup(struct mm_struct *mm)
  84 {
  85         smp_mb();
  86         smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1);
  87 }
  88
  89 /*
  90  * We use this to invalidate a pmdp entry before switching from a
  91  * hugepte to regular pmd entry.
  92  */
  93 pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
  94                      pmd_t *pmdp)
  95 {
  96         unsigned long old_pmd;
  97
  98         old_pmd = pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, 0);
  99         flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 100         /*
 101          * This ensures that generic code that rely on IRQ disabling
 102          * to prevent a parallel THP split work as expected.
 103          */
 104         serialize_against_pte_lookup(vma->vm_mm);
 105         return __pmd(old_pmd);
 106 }
 107
 108 static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
 109 {
 110         return __pmd(pmd_val(pmd) | pgprot_val(pgprot));
 111 }
 112
 113 pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
 114 {
 115         unsigned long pmdv;
 116
 117         pmdv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;
 118         return pmd_set_protbits(__pmd(pmdv), pgprot);
 119 }
 120
 121 pmd_t mk_pmd(struct page *page, pgprot_t pgprot)
 122 {
 123         return pfn_pmd(page_to_pfn(page), pgprot);
 124 }
 125
 126 pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 127 {
 128         unsigned long pmdv;
 129
 130         pmdv = pmd_val(pmd);
 131         pmdv &= _HPAGE_CHG_MASK;
 132         return pmd_set_protbits(__pmd(pmdv), newprot);
 133 }
 134
 135 /*
 136  * This is called at the end of handling a user page fault, when the
 137  * fault has been handled by updating a HUGE PMD entry in the linux page tables.
 138  * We use it to preload an HPTE into the hash table corresponding to
 139  * the updated linux HUGE PMD entry.
 140  */
 141 void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
 142                           pmd_t *pmd)
 143 {
 144         return;
 145 }
 146 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 147
 148 /* For use by kexec */
 149 void mmu_cleanup_all(void)
 150 {
 151         if (radix_enabled())
 152                 radix__mmu_cleanup_all();
 153         else if (mmu_hash_ops.hpte_clear_all)
 154                 mmu_hash_ops.hpte_clear_all();
 155 }
 156
 157 #ifdef CONFIG_MEMORY_HOTPLUG
 158 int __meminit create_section_mapping(unsigned long start, unsigned long end)
 159 {
 160         if (radix_enabled())
 161                 return radix__create_section_mapping(start, end);
 162
 163         return hash__create_section_mapping(start, end);
 164 }
 165
 166 int __meminit remove_section_mapping(unsigned long start, unsigned long end)
 167 {
 168         if (radix_enabled())
 169                 return radix__remove_section_mapping(start, end);
 170
 171         return hash__remove_section_mapping(start, end);
 172 }
 173 #endif /* CONFIG_MEMORY_HOTPLUG */