arch/x86/mm/hugetlbpage.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * IA-32 Huge TLB Page Support for Kernel.
   4  *
   5  * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/fs.h>
  10 #include <linux/mm.h>
  11 #include <linux/sched/mm.h>
  12 #include <linux/hugetlb.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/err.h>
  15 #include <linux/sysctl.h>
  16 #include <linux/compat.h>
  17 #include <asm/mman.h>
  18 #include <asm/tlb.h>
  19 #include <asm/tlbflush.h>
  20 #include <asm/elf.h>
  21
  22 #if 0   /* This is just for testing */
  23 struct page *
  24 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  25 {
  26         unsigned long start = address;
  27         int length = 1;
  28         int nr;
  29         struct page *page;
  30         struct vm_area_struct *vma;
  31
  32         vma = find_vma(mm, addr);
  33         if (!vma || !is_vm_hugetlb_page(vma))
  34                 return ERR_PTR(-EINVAL);
  35
  36         pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
  37
  38         /* hugetlb should be locked, and hence, prefaulted */
  39         WARN_ON(!pte || pte_none(*pte));
  40
  41         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
  42
  43         WARN_ON(!PageHead(page));
  44
  45         return page;
  46 }
  47
  48 int pmd_huge(pmd_t pmd)
  49 {
  50         return 0;
  51 }
  52
  53 int pud_huge(pud_t pud)
  54 {
  55         return 0;
  56 }
  57
  58 #else
  59
  60 /*
  61  * pmd_huge() returns 1 if @pmd is hugetlb related entry, that is normal
  62  * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry.
  63  * Otherwise, returns 0.
  64  */
  65 int pmd_huge(pmd_t pmd)
  66 {
  67         return !pmd_none(pmd) &&
  68                 (pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT;
  69 }
  70
  71 int pud_huge(pud_t pud)
  72 {
  73         return !!(pud_val(pud) & _PAGE_PSE);
  74 }
  75 #endif
  76
  77 #ifdef CONFIG_HUGETLB_PAGE
  78 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
  79                 unsigned long addr, unsigned long len,
  80                 unsigned long pgoff, unsigned long flags)
  81 {
  82         struct hstate *h = hstate_file(file);
  83         struct vm_unmapped_area_info info;
  84
  85         info.flags = 0;
  86         info.length = len;
  87         info.low_limit = get_mmap_base(1);
  88
  89         /*
  90          * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
  91          * in the full address space.
  92          */
  93         info.high_limit = in_32bit_syscall() ?
  94                 task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
  95
  96         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
  97         info.align_offset = 0;
  98         return vm_unmapped_area(&info);
  99 }
 100
 101 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 102                 unsigned long addr, unsigned long len,
 103                 unsigned long pgoff, unsigned long flags)
 104 {
 105         struct hstate *h = hstate_file(file);
 106         struct vm_unmapped_area_info info;
 107
 108         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 109         info.length = len;
 110         info.low_limit = PAGE_SIZE;
 111         info.high_limit = get_mmap_base(0);
 112
 113         /*
 114          * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 115          * in the full address space.
 116          */
 117         if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 118                 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 119
 120         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 121         info.align_offset = 0;
 122         addr = vm_unmapped_area(&info);
 123
 124         /*
 125          * A failed mmap() very likely causes application failure,
 126          * so fall back to the bottom-up function here. This scenario
 127          * can happen with large stack limits and large mmap()
 128          * allocations.
 129          */
 130         if (addr & ~PAGE_MASK) {
 131                 VM_BUG_ON(addr != -ENOMEM);
 132                 info.flags = 0;
 133                 info.low_limit = TASK_UNMAPPED_BASE;
 134                 info.high_limit = TASK_SIZE_LOW;
 135                 addr = vm_unmapped_area(&info);
 136         }
 137
 138         return addr;
 139 }
 140
 141 unsigned long
 142 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 143                 unsigned long len, unsigned long pgoff, unsigned long flags)
 144 {
 145         struct hstate *h = hstate_file(file);
 146         struct mm_struct *mm = current->mm;
 147         struct vm_area_struct *vma;
 148
 149         if (len & ~huge_page_mask(h))
 150                 return -EINVAL;
 151
 152         if (len > TASK_SIZE)
 153                 return -ENOMEM;
 154
 155         /* No address checking. See comment at mmap_address_hint_valid() */
 156         if (flags & MAP_FIXED) {
 157                 if (prepare_hugepage_range(file, addr, len))
 158                         return -EINVAL;
 159                 return addr;
 160         }
 161
 162         if (addr) {
 163                 addr &= huge_page_mask(h);
 164                 if (!mmap_address_hint_valid(addr, len))
 165                         goto get_unmapped_area;
 166
 167                 vma = find_vma(mm, addr);
 168                 if (!vma || addr + len <= vm_start_gap(vma))
 169                         return addr;
 170         }
 171
 172 get_unmapped_area:
 173         if (mm->get_unmapped_area == arch_get_unmapped_area)
 174                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 175                                 pgoff, flags);
 176         else
 177                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 178                                 pgoff, flags);
 179 }
 180 #endif /* CONFIG_HUGETLB_PAGE */
 181
 182 #ifdef CONFIG_X86_64
 183 bool __init arch_hugetlb_valid_size(unsigned long size)
 184 {
 185         if (size == PMD_SIZE)
 186                 return true;
 187         else if (size == PUD_SIZE && boot_cpu_has(X86_FEATURE_GBPAGES))
 188                 return true;
 189         else
 190                 return false;
 191 }
 192
 193 #ifdef CONFIG_CONTIG_ALLOC
 194 static __init int gigantic_pages_init(void)
 195 {
 196         /* With compaction or CMA we can allocate gigantic pages at runtime */
 197         if (boot_cpu_has(X86_FEATURE_GBPAGES))
 198                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 199         return 0;
 200 }
 201 arch_initcall(gigantic_pages_init);
 202 #endif
 203 #endif