arch/powerpc/mm/mmu_context_iommu.c

   1 /*
   2  *  IOMMU helpers in MMU context.
   3  *
   4  *  Copyright (C) 2015 IBM Corp. <aik@ozlabs.ru>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/rculist.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/mutex.h>
  18 #include <asm/mmu_context.h>
  19
  20 static DEFINE_MUTEX(mem_list_mutex);
  21
  22 struct mm_iommu_table_group_mem_t {
  23         struct list_head next;
  24         struct rcu_head rcu;
  25         unsigned long used;
  26         atomic64_t mapped;
  27         u64 ua;                 /* userspace address */
  28         u64 entries;            /* number of entries in hpas[] */
  29         u64 *hpas;              /* vmalloc'ed */
  30 };
  31
  32 static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
  33                 unsigned long npages, bool incr)
  34 {
  35         long ret = 0, locked, lock_limit;
  36
  37         if (!npages)
  38                 return 0;
  39
  40         down_write(&mm->mmap_sem);
  41
  42         if (incr) {
  43                 locked = mm->locked_vm + npages;
  44                 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  45                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
  46                         ret = -ENOMEM;
  47                 else
  48                         mm->locked_vm += npages;
  49         } else {
  50                 if (WARN_ON_ONCE(npages > mm->locked_vm))
  51                         npages = mm->locked_vm;
  52                 mm->locked_vm -= npages;
  53         }
  54
  55         pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
  56                         current->pid,
  57                         incr ? '+' : '-',
  58                         npages << PAGE_SHIFT,
  59                         mm->locked_vm << PAGE_SHIFT,
  60                         rlimit(RLIMIT_MEMLOCK));
  61         up_write(&mm->mmap_sem);
  62
  63         return ret;
  64 }
  65
  66 bool mm_iommu_preregistered(void)
  67 {
  68         if (!current || !current->mm)
  69                 return false;
  70
  71         return !list_empty(&current->mm->context.iommu_group_mem_list);
  72 }
  73 EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
  74
  75 long mm_iommu_get(unsigned long ua, unsigned long entries,
  76                 struct mm_iommu_table_group_mem_t **pmem)
  77 {
  78         struct mm_iommu_table_group_mem_t *mem;
  79         long i, j, ret = 0, locked_entries = 0;
  80         struct page *page = NULL;
  81
  82         if (!current || !current->mm)
  83                 return -ESRCH; /* process exited */
  84
  85         mutex_lock(&mem_list_mutex);
  86
  87         list_for_each_entry_rcu(mem, &current->mm->context.iommu_group_mem_list,
  88                         next) {
  89                 if ((mem->ua == ua) && (mem->entries == entries)) {
  90                         ++mem->used;
  91                         *pmem = mem;
  92                         goto unlock_exit;
  93                 }
  94
  95                 /* Overlap? */
  96                 if ((mem->ua < (ua + (entries << PAGE_SHIFT))) &&
  97                                 (ua < (mem->ua +
  98                                        (mem->entries << PAGE_SHIFT)))) {
  99                         ret = -EINVAL;
 100                         goto unlock_exit;
 101                 }
 102
 103         }
 104
 105         ret = mm_iommu_adjust_locked_vm(current->mm, entries, true);
 106         if (ret)
 107                 goto unlock_exit;
 108
 109         locked_entries = entries;
 110
 111         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 112         if (!mem) {
 113                 ret = -ENOMEM;
 114                 goto unlock_exit;
 115         }
 116
 117         mem->hpas = vzalloc(entries * sizeof(mem->hpas[0]));
 118         if (!mem->hpas) {
 119                 kfree(mem);
 120                 ret = -ENOMEM;
 121                 goto unlock_exit;
 122         }
 123
 124         for (i = 0; i < entries; ++i) {
 125                 if (1 != get_user_pages_fast(ua + (i << PAGE_SHIFT),
 126                                         1/* pages */, 1/* iswrite */, &page)) {
 127                         for (j = 0; j < i; ++j)
 128                                 put_page(pfn_to_page(
 129                                                 mem->hpas[j] >> PAGE_SHIFT));
 130                         vfree(mem->hpas);
 131                         kfree(mem);
 132                         ret = -EFAULT;
 133                         goto unlock_exit;
 134                 }
 135
 136                 mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
 137         }
 138
 139         atomic64_set(&mem->mapped, 1);
 140         mem->used = 1;
 141         mem->ua = ua;
 142         mem->entries = entries;
 143         *pmem = mem;
 144
 145         list_add_rcu(&mem->next, &current->mm->context.iommu_group_mem_list);
 146
 147 unlock_exit:
 148         if (locked_entries && ret)
 149                 mm_iommu_adjust_locked_vm(current->mm, locked_entries, false);
 150
 151         mutex_unlock(&mem_list_mutex);
 152
 153         return ret;
 154 }
 155 EXPORT_SYMBOL_GPL(mm_iommu_get);
 156
 157 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 158 {
 159         long i;
 160         struct page *page = NULL;
 161
 162         for (i = 0; i < mem->entries; ++i) {
 163                 if (!mem->hpas[i])
 164                         continue;
 165
 166                 page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
 167                 if (!page)
 168                         continue;
 169
 170                 put_page(page);
 171                 mem->hpas[i] = 0;
 172         }
 173 }
 174
 175 static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
 176 {
 177
 178         mm_iommu_unpin(mem);
 179         vfree(mem->hpas);
 180         kfree(mem);
 181 }
 182
 183 static void mm_iommu_free(struct rcu_head *head)
 184 {
 185         struct mm_iommu_table_group_mem_t *mem = container_of(head,
 186                         struct mm_iommu_table_group_mem_t, rcu);
 187
 188         mm_iommu_do_free(mem);
 189 }
 190
 191 static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
 192 {
 193         list_del_rcu(&mem->next);
 194         mm_iommu_adjust_locked_vm(current->mm, mem->entries, false);
 195         call_rcu(&mem->rcu, mm_iommu_free);
 196 }
 197
 198 long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
 199 {
 200         long ret = 0;
 201
 202         if (!current || !current->mm)
 203                 return -ESRCH; /* process exited */
 204
 205         mutex_lock(&mem_list_mutex);
 206
 207         if (mem->used == 0) {
 208                 ret = -ENOENT;
 209                 goto unlock_exit;
 210         }
 211
 212         --mem->used;
 213         /* There are still users, exit */
 214         if (mem->used)
 215                 goto unlock_exit;
 216
 217         /* Are there still mappings? */
 218         if (atomic_cmpxchg(&mem->mapped, 1, 0) != 1) {
 219                 ++mem->used;
 220                 ret = -EBUSY;
 221                 goto unlock_exit;
 222         }
 223
 224         /* @mapped became 0 so now mappings are disabled, release the region */
 225         mm_iommu_release(mem);
 226
 227 unlock_exit:
 228         mutex_unlock(&mem_list_mutex);
 229
 230         return ret;
 231 }
 232 EXPORT_SYMBOL_GPL(mm_iommu_put);
 233
 234 struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
 235                 unsigned long size)
 236 {
 237         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 238
 239         list_for_each_entry_rcu(mem,
 240                         &current->mm->context.iommu_group_mem_list,
 241                         next) {
 242                 if ((mem->ua <= ua) &&
 243                                 (ua + size <= mem->ua +
 244                                  (mem->entries << PAGE_SHIFT))) {
 245                         ret = mem;
 246                         break;
 247                 }
 248         }
 249
 250         return ret;
 251 }
 252 EXPORT_SYMBOL_GPL(mm_iommu_lookup);
 253
 254 struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
 255                 unsigned long entries)
 256 {
 257         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 258
 259         list_for_each_entry_rcu(mem,
 260                         &current->mm->context.iommu_group_mem_list,
 261                         next) {
 262                 if ((mem->ua == ua) && (mem->entries == entries)) {
 263                         ret = mem;
 264                         break;
 265                 }
 266         }
 267
 268         return ret;
 269 }
 270 EXPORT_SYMBOL_GPL(mm_iommu_find);
 271
 272 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 273                 unsigned long ua, unsigned long *hpa)
 274 {
 275         const long entry = (ua - mem->ua) >> PAGE_SHIFT;
 276         u64 *va = &mem->hpas[entry];
 277
 278         if (entry >= mem->entries)
 279                 return -EFAULT;
 280
 281         *hpa = *va | (ua & ~PAGE_MASK);
 282
 283         return 0;
 284 }
 285 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
 286
 287 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
 288 {
 289         if (atomic64_inc_not_zero(&mem->mapped))
 290                 return 0;
 291
 292         /* Last mm_iommu_put() has been called, no more mappings allowed() */
 293         return -ENXIO;
 294 }
 295 EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
 296
 297 void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
 298 {
 299         atomic64_add_unless(&mem->mapped, -1, 1);
 300 }
 301 EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
 302
 303 void mm_iommu_init(mm_context_t *ctx)
 304 {
 305         INIT_LIST_HEAD_RCU(&ctx->iommu_group_mem_list);
 306 }
 307
 308 void mm_iommu_cleanup(mm_context_t *ctx)
 309 {
 310         struct mm_iommu_table_group_mem_t *mem, *tmp;
 311
 312         list_for_each_entry_safe(mem, tmp, &ctx->iommu_group_mem_list, next) {
 313                 list_del_rcu(&mem->next);
 314                 mm_iommu_do_free(mem);
 315         }
 316 }