arch/powerpc/mm/book3s64/subpage

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This source file includes following definitions.
subpage_prot_free
hpte_flush_range
subpage_prot_clear
subpage_walk_pmd_entry
subpage_mark_vma_nohuge
subpage_mark_vma_nohuge
SYSCALL_DEFINE3
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2007-2008 Paul Mackerras, IBM Corp.
   4  */
   5 
   6 #include <linux/errno.h>
   7 #include <linux/kernel.h>
   8 #include <linux/gfp.h>
   9 #include <linux/types.h>
  10 #include <linux/pagewalk.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/syscalls.h>
  13 
  14 #include <asm/pgtable.h>
  15 #include <linux/uaccess.h>
  16 
  17 /*
  18  * Free all pages allocated for subpage protection maps and pointers.
  19  * Also makes sure that the subpage_prot_table structure is
  20  * reinitialized for the next user.
  21  */
  22 void subpage_prot_free(struct mm_struct *mm)
  23 {
  24         struct subpage_prot_table *spt = mm_ctx_subpage_prot(&mm->context);
  25         unsigned long i, j, addr;
  26         u32 **p;
  27 
  28         if (!spt)
  29                 return;
  30 
  31         for (i = 0; i < 4; ++i) {
  32                 if (spt->low_prot[i]) {
  33                         free_page((unsigned long)spt->low_prot[i]);
  34                         spt->low_prot[i] = NULL;
  35                 }
  36         }
  37         addr = 0;
  38         for (i = 0; i < (TASK_SIZE_USER64 >> 43); ++i) {
  39                 p = spt->protptrs[i];
  40                 if (!p)
  41                         continue;
  42                 spt->protptrs[i] = NULL;
  43                 for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr;
  44                      ++j, addr += PAGE_SIZE)
  45                         if (p[j])
  46                                 free_page((unsigned long)p[j]);
  47                 free_page((unsigned long)p);
  48         }
  49         spt->maxaddr = 0;
  50         kfree(spt);
  51 }
  52 
  53 static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
  54                              int npages)
  55 {
  56         pgd_t *pgd;
  57         pud_t *pud;
  58         pmd_t *pmd;
  59         pte_t *pte;
  60         spinlock_t *ptl;
  61 
  62         pgd = pgd_offset(mm, addr);
  63         if (pgd_none(*pgd))
  64                 return;
  65         pud = pud_offset(pgd, addr);
  66         if (pud_none(*pud))
  67                 return;
  68         pmd = pmd_offset(pud, addr);
  69         if (pmd_none(*pmd))
  70                 return;
  71         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
  72         arch_enter_lazy_mmu_mode();
  73         for (; npages > 0; --npages) {
  74                 pte_update(mm, addr, pte, 0, 0, 0);
  75                 addr += PAGE_SIZE;
  76                 ++pte;
  77         }
  78         arch_leave_lazy_mmu_mode();
  79         pte_unmap_unlock(pte - 1, ptl);
  80 }
  81 
  82 /*
  83  * Clear the subpage protection map for an address range, allowing
  84  * all accesses that are allowed by the pte permissions.
  85  */
  86 static void subpage_prot_clear(unsigned long addr, unsigned long len)
  87 {
  88         struct mm_struct *mm = current->mm;
  89         struct subpage_prot_table *spt;
  90         u32 **spm, *spp;
  91         unsigned long i;
  92         size_t nw;
  93         unsigned long next, limit;
  94 
  95         down_write(&mm->mmap_sem);
  96 
  97         spt = mm_ctx_subpage_prot(&mm->context);
  98         if (!spt)
  99                 goto err_out;
 100 
 101         limit = addr + len;
 102         if (limit > spt->maxaddr)
 103                 limit = spt->maxaddr;
 104         for (; addr < limit; addr = next) {
 105                 next = pmd_addr_end(addr, limit);
 106                 if (addr < 0x100000000UL) {
 107                         spm = spt->low_prot;
 108                 } else {
 109                         spm = spt->protptrs[addr >> SBP_L3_SHIFT];
 110                         if (!spm)
 111                                 continue;
 112                 }
 113                 spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
 114                 if (!spp)
 115                         continue;
 116                 spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
 117 
 118                 i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 119                 nw = PTRS_PER_PTE - i;
 120                 if (addr + (nw << PAGE_SHIFT) > next)
 121                         nw = (next - addr) >> PAGE_SHIFT;
 122 
 123                 memset(spp, 0, nw * sizeof(u32));
 124 
 125                 /* now flush any existing HPTEs for the range */
 126                 hpte_flush_range(mm, addr, nw);
 127         }
 128 
 129 err_out:
 130         up_write(&mm->mmap_sem);
 131 }
 132 
 133 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 134 static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
 135                                   unsigned long end, struct mm_walk *walk)
 136 {
 137         struct vm_area_struct *vma = walk->vma;
 138         split_huge_pmd(vma, pmd, addr);
 139         return 0;
 140 }
 141 
 142 static const struct mm_walk_ops subpage_walk_ops = {
 143         .pmd_entry      = subpage_walk_pmd_entry,
 144 };
 145 
 146 static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
 147                                     unsigned long len)
 148 {
 149         struct vm_area_struct *vma;
 150 
 151         /*
 152          * We don't try too hard, we just mark all the vma in that range
 153          * VM_NOHUGEPAGE and split them.
 154          */
 155         vma = find_vma(mm, addr);
 156         /*
 157          * If the range is in unmapped range, just return
 158          */
 159         if (vma && ((addr + len) <= vma->vm_start))
 160                 return;
 161 
 162         while (vma) {
 163                 if (vma->vm_start >= (addr + len))
 164                         break;
 165                 vma->vm_flags |= VM_NOHUGEPAGE;
 166                 walk_page_vma(vma, &subpage_walk_ops, NULL);
 167                 vma = vma->vm_next;
 168         }
 169 }
 170 #else
 171 static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
 172                                     unsigned long len)
 173 {
 174         return;
 175 }
 176 #endif
 177 
 178 /*
 179  * Copy in a subpage protection map for an address range.
 180  * The map has 2 bits per 4k subpage, so 32 bits per 64k page.
 181  * Each 2-bit field is 0 to allow any access, 1 to prevent writes,
 182  * 2 or 3 to prevent all accesses.
 183  * Note that the normal page protections also apply; the subpage
 184  * protection mechanism is an additional constraint, so putting 0
 185  * in a 2-bit field won't allow writes to a page that is otherwise
 186  * write-protected.
 187  */
 188 SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
 189                 unsigned long, len, u32 __user *, map)
 190 {
 191         struct mm_struct *mm = current->mm;
 192         struct subpage_prot_table *spt;
 193         u32 **spm, *spp;
 194         unsigned long i;
 195         size_t nw;
 196         unsigned long next, limit;
 197         int err;
 198 
 199         if (radix_enabled())
 200                 return -ENOENT;
 201 
 202         /* Check parameters */
 203         if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
 204             addr >= mm->task_size || len >= mm->task_size ||
 205             addr + len > mm->task_size)
 206                 return -EINVAL;
 207 
 208         if (is_hugepage_only_range(mm, addr, len))
 209                 return -EINVAL;
 210 
 211         if (!map) {
 212                 /* Clear out the protection map for the address range */
 213                 subpage_prot_clear(addr, len);
 214                 return 0;
 215         }
 216 
 217         if (!access_ok(map, (len >> PAGE_SHIFT) * sizeof(u32)))
 218                 return -EFAULT;
 219 
 220         down_write(&mm->mmap_sem);
 221 
 222         spt = mm_ctx_subpage_prot(&mm->context);
 223         if (!spt) {
 224                 /*
 225                  * Allocate subpage prot table if not already done.
 226                  * Do this with mmap_sem held
 227                  */
 228                 spt = kzalloc(sizeof(struct subpage_prot_table), GFP_KERNEL);
 229                 if (!spt) {
 230                         err = -ENOMEM;
 231                         goto out;
 232                 }
 233                 mm->context.hash_context->spt = spt;
 234         }
 235 
 236         subpage_mark_vma_nohuge(mm, addr, len);
 237         for (limit = addr + len; addr < limit; addr = next) {
 238                 next = pmd_addr_end(addr, limit);
 239                 err = -ENOMEM;
 240                 if (addr < 0x100000000UL) {
 241                         spm = spt->low_prot;
 242                 } else {
 243                         spm = spt->protptrs[addr >> SBP_L3_SHIFT];
 244                         if (!spm) {
 245                                 spm = (u32 **)get_zeroed_page(GFP_KERNEL);
 246                                 if (!spm)
 247                                         goto out;
 248                                 spt->protptrs[addr >> SBP_L3_SHIFT] = spm;
 249                         }
 250                 }
 251                 spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1);
 252                 spp = *spm;
 253                 if (!spp) {
 254                         spp = (u32 *)get_zeroed_page(GFP_KERNEL);
 255                         if (!spp)
 256                                 goto out;
 257                         *spm = spp;
 258                 }
 259                 spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
 260 
 261                 local_irq_disable();
 262                 demote_segment_4k(mm, addr);
 263                 local_irq_enable();
 264 
 265                 i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 266                 nw = PTRS_PER_PTE - i;
 267                 if (addr + (nw << PAGE_SHIFT) > next)
 268                         nw = (next - addr) >> PAGE_SHIFT;
 269 
 270                 up_write(&mm->mmap_sem);
 271                 if (__copy_from_user(spp, map, nw * sizeof(u32)))
 272                         return -EFAULT;
 273                 map += nw;
 274                 down_write(&mm->mmap_sem);
 275 
 276                 /* now flush any existing HPTEs for the range */
 277                 hpte_flush_range(mm, addr, nw);
 278         }
 279         if (limit > spt->maxaddr)
 280                 spt->maxaddr = limit;
 281         err = 0;
 282  out:
 283         up_write(&mm->mmap_sem);
 284         return err;
 285 }
/* [<][>][^][v][top][bottom][index][help] */
root/arch/powerpc/mm/book3s64/subpage_prot.c

DEFINITIONS
