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/pgalloc.h>
  21 #include <asm/elf.h>
  22 #include <asm/mpx.h>
  23
  24 #if 0   /* This is just for testing */
  25 struct page *
  26 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  27 {
  28         unsigned long start = address;
  29         int length = 1;
  30         int nr;
  31         struct page *page;
  32         struct vm_area_struct *vma;
  33
  34         vma = find_vma(mm, addr);
  35         if (!vma || !is_vm_hugetlb_page(vma))
  36                 return ERR_PTR(-EINVAL);
  37
  38         pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
  39
  40         /* hugetlb should be locked, and hence, prefaulted */
  41         WARN_ON(!pte || pte_none(*pte));
  42
  43         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
  44
  45         WARN_ON(!PageHead(page));
  46
  47         return page;
  48 }
  49
  50 int pmd_huge(pmd_t pmd)
  51 {
  52         return 0;
  53 }
  54
  55 int pud_huge(pud_t pud)
  56 {
  57         return 0;
  58 }
  59
  60 #else
  61
  62 /*
  63  * pmd_huge() returns 1 if @pmd is hugetlb related entry, that is normal
  64  * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry.
  65  * Otherwise, returns 0.
  66  */
  67 int pmd_huge(pmd_t pmd)
  68 {
  69         return !pmd_none(pmd) &&
  70                 (pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT;
  71 }
  72
  73 int pud_huge(pud_t pud)
  74 {
  75         return !!(pud_val(pud) & _PAGE_PSE);
  76 }
  77 #endif
  78
  79 #ifdef CONFIG_HUGETLB_PAGE
  80 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
  81                 unsigned long addr, unsigned long len,
  82                 unsigned long pgoff, unsigned long flags)
  83 {
  84         struct hstate *h = hstate_file(file);
  85         struct vm_unmapped_area_info info;
  86
  87         info.flags = 0;
  88         info.length = len;
  89         info.low_limit = get_mmap_base(1);
  90
  91         /*
  92          * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
  93          * in the full address space.
  94          */
  95         info.high_limit = in_compat_syscall() ?
  96                 task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
  97
  98         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
  99         info.align_offset = 0;
 100         return vm_unmapped_area(&info);
 101 }
 102
 103 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 104                 unsigned long addr, unsigned long len,
 105                 unsigned long pgoff, unsigned long flags)
 106 {
 107         struct hstate *h = hstate_file(file);
 108         struct vm_unmapped_area_info info;
 109
 110         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 111         info.length = len;
 112         info.low_limit = PAGE_SIZE;
 113         info.high_limit = get_mmap_base(0);
 114
 115         /*
 116          * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 117          * in the full address space.
 118          */
 119         if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
 120                 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 121
 122         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 123         info.align_offset = 0;
 124         addr = vm_unmapped_area(&info);
 125
 126         /*
 127          * A failed mmap() very likely causes application failure,
 128          * so fall back to the bottom-up function here. This scenario
 129          * can happen with large stack limits and large mmap()
 130          * allocations.
 131          */
 132         if (addr & ~PAGE_MASK) {
 133                 VM_BUG_ON(addr != -ENOMEM);
 134                 info.flags = 0;
 135                 info.low_limit = TASK_UNMAPPED_BASE;
 136                 info.high_limit = TASK_SIZE_LOW;
 137                 addr = vm_unmapped_area(&info);
 138         }
 139
 140         return addr;
 141 }
 142
 143 unsigned long
 144 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 145                 unsigned long len, unsigned long pgoff, unsigned long flags)
 146 {
 147         struct hstate *h = hstate_file(file);
 148         struct mm_struct *mm = current->mm;
 149         struct vm_area_struct *vma;
 150
 151         if (len & ~huge_page_mask(h))
 152                 return -EINVAL;
 153
 154         addr = mpx_unmapped_area_check(addr, len, flags);
 155         if (IS_ERR_VALUE(addr))
 156                 return addr;
 157
 158         if (len > TASK_SIZE)
 159                 return -ENOMEM;
 160
 161         if (flags & MAP_FIXED) {
 162                 if (prepare_hugepage_range(file, addr, len))
 163                         return -EINVAL;
 164                 return addr;
 165         }
 166
 167         if (addr) {
 168                 addr = ALIGN(addr, huge_page_size(h));
 169                 vma = find_vma(mm, addr);
 170                 if (TASK_SIZE - len >= addr &&
 171                     (!vma || addr + len <= vm_start_gap(vma)))
 172                         return addr;
 173         }
 174         if (mm->get_unmapped_area == arch_get_unmapped_area)
 175                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 176                                 pgoff, flags);
 177         else
 178                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 179                                 pgoff, flags);
 180 }
 181 #endif /* CONFIG_HUGETLB_PAGE */
 182
 183 #ifdef CONFIG_X86_64
 184 static __init int setup_hugepagesz(char *opt)
 185 {
 186         unsigned long ps = memparse(opt, &opt);
 187         if (ps == PMD_SIZE) {
 188                 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
 189         } else if (ps == PUD_SIZE && boot_cpu_has(X86_FEATURE_GBPAGES)) {
 190                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 191         } else {
 192                 hugetlb_bad_size();
 193                 printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
 194                         ps >> 20);
 195                 return 0;
 196         }
 197         return 1;
 198 }
 199 __setup("hugepagesz=", setup_hugepagesz);
 200
 201 #if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
 202 static __init int gigantic_pages_init(void)
 203 {
 204         /* With compaction or CMA we can allocate gigantic pages at runtime */
 205         if (boot_cpu_has(X86_FEATURE_GBPAGES) && !size_to_hstate(1UL << PUD_SHIFT))
 206                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 207         return 0;
 208 }
 209 arch_initcall(gigantic_pages_init);
 210 #endif
 211 #endif