arch/powerpc/mm/book3s64/hash_64k.c

   1 /*
   2  * Copyright IBM Corporation, 2015
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/mm.h>
  16 #include <asm/machdep.h>
  17 #include <asm/mmu.h>
  18
  19 /*
  20  * Return true, if the entry has a slot value which
  21  * the software considers as invalid.
  22  */
  23 static inline bool hpte_soft_invalid(unsigned long hidx)
  24 {
  25         return ((hidx & 0xfUL) == 0xfUL);
  26 }
  27
  28 /*
  29  * index from 0 - 15
  30  */
  31 bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
  32 {
  33         return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index)));
  34 }
  35
  36 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
  37                    pte_t *ptep, unsigned long trap, unsigned long flags,
  38                    int ssize, int subpg_prot)
  39 {
  40         real_pte_t rpte;
  41         unsigned long hpte_group;
  42         unsigned int subpg_index;
  43         unsigned long rflags, pa;
  44         unsigned long old_pte, new_pte, subpg_pte;
  45         unsigned long vpn, hash, slot, gslot;
  46         unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
  47
  48         /*
  49          * atomically mark the linux large page PTE busy and dirty
  50          */
  51         do {
  52                 pte_t pte = READ_ONCE(*ptep);
  53
  54                 old_pte = pte_val(pte);
  55                 /* If PTE busy, retry the access */
  56                 if (unlikely(old_pte & H_PAGE_BUSY))
  57                         return 0;
  58                 /* If PTE permissions don't match, take page fault */
  59                 if (unlikely(!check_pte_access(access, old_pte)))
  60                         return 1;
  61                 /*
  62                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  63                  * a write access. Since this is 4K insert of 64K page size
  64                  * also add H_PAGE_COMBO
  65                  */
  66                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED | H_PAGE_COMBO;
  67                 if (access & _PAGE_WRITE)
  68                         new_pte |= _PAGE_DIRTY;
  69         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
  70
  71         /*
  72          * Handle the subpage protection bits
  73          */
  74         subpg_pte = new_pte & ~subpg_prot;
  75         rflags = htab_convert_pte_flags(subpg_pte);
  76
  77         if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
  78             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
  79
  80                 /*
  81                  * No CPU has hugepages but lacks no execute, so we
  82                  * don't need to worry about that case
  83                  */
  84                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  85         }
  86
  87         subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
  88         vpn  = hpt_vpn(ea, vsid, ssize);
  89         rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
  90         /*
  91          *None of the sub 4k page is hashed
  92          */
  93         if (!(old_pte & H_PAGE_HASHPTE))
  94                 goto htab_insert_hpte;
  95         /*
  96          * Check if the pte was already inserted into the hash table
  97          * as a 64k HW page, and invalidate the 64k HPTE if so.
  98          */
  99         if (!(old_pte & H_PAGE_COMBO)) {
 100                 flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
 101                 /*
 102                  * clear the old slot details from the old and new pte.
 103                  * On hash insert failure we use old pte value and we don't
 104                  * want slot information there if we have a insert failure.
 105                  */
 106                 old_pte &= ~H_PAGE_HASHPTE;
 107                 new_pte &= ~H_PAGE_HASHPTE;
 108                 goto htab_insert_hpte;
 109         }
 110         /*
 111          * Check for sub page valid and update
 112          */
 113         if (__rpte_sub_valid(rpte, subpg_index)) {
 114                 int ret;
 115
 116                 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte,
 117                                            subpg_index);
 118                 ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn,
 119                                                  MMU_PAGE_4K, MMU_PAGE_4K,
 120                                                  ssize, flags);
 121
 122                 /*
 123                  * If we failed because typically the HPTE wasn't really here
 124                  * we try an insertion.
 125                  */
 126                 if (ret == -1)
 127                         goto htab_insert_hpte;
 128
 129                 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 130                 return 0;
 131         }
 132
 133 htab_insert_hpte:
 134
 135         /*
 136          * Initialize all hidx entries to invalid value, the first time
 137          * the PTE is about to allocate a 4K HPTE.
 138          */
 139         if (!(old_pte & H_PAGE_COMBO))
 140                 rpte.hidx = INVALID_RPTE_HIDX;
 141
 142         /*
 143          * handle H_PAGE_4K_PFN case
 144          */
 145         if (old_pte & H_PAGE_4K_PFN) {
 146                 /*
 147                  * All the sub 4k page have the same
 148                  * physical address.
 149                  */
 150                 pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
 151         } else {
 152                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 153                 pa += (subpg_index << shift);
 154         }
 155         hash = hpt_hash(vpn, shift, ssize);
 156 repeat:
 157         hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 158
 159         /* Insert into the hash table, primary slot */
 160         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 161                                         MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 162         /*
 163          * Primary is full, try the secondary
 164          */
 165         if (unlikely(slot == -1)) {
 166                 bool soft_invalid;
 167
 168                 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
 169                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 170                                                 rflags, HPTE_V_SECONDARY,
 171                                                 MMU_PAGE_4K, MMU_PAGE_4K,
 172                                                 ssize);
 173
 174                 soft_invalid = hpte_soft_invalid(slot);
 175                 if (unlikely(soft_invalid)) {
 176                         /*
 177                          * We got a valid slot from a hardware point of view.
 178                          * but we cannot use it, because we use this special
 179                          * value; as defined by hpte_soft_invalid(), to track
 180                          * invalid slots. We cannot use it. So invalidate it.
 181                          */
 182                         gslot = slot & _PTEIDX_GROUP_IX;
 183                         mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
 184                                                      MMU_PAGE_4K, MMU_PAGE_4K,
 185                                                      ssize, 0);
 186                 }
 187
 188                 if (unlikely(slot == -1 || soft_invalid)) {
 189                         /*
 190                          * For soft invalid slot, let's ensure that we release a
 191                          * slot from the primary, with the hope that we will
 192                          * acquire that slot next time we try. This will ensure
 193                          * that we do not get the same soft-invalid slot.
 194                          */
 195                         if (soft_invalid || (mftb() & 0x1))
 196                                 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 197
 198                         mmu_hash_ops.hpte_remove(hpte_group);
 199                         /*
 200                          * FIXME!! Should be try the group from which we removed ?
 201                          */
 202                         goto repeat;
 203                 }
 204         }
 205         /*
 206          * Hypervisor failure. Restore old pte and return -1
 207          * similar to __hash_page_*
 208          */
 209         if (unlikely(slot == -2)) {
 210                 *ptep = __pte(old_pte);
 211                 hash_failure_debug(ea, access, vsid, trap, ssize,
 212                                    MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 213                 return -1;
 214         }
 215
 216         new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
 217         new_pte |= H_PAGE_HASHPTE;
 218
 219         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 220         return 0;
 221 }
 222
 223 int __hash_page_64K(unsigned long ea, unsigned long access,
 224                     unsigned long vsid, pte_t *ptep, unsigned long trap,
 225                     unsigned long flags, int ssize)
 226 {
 227         real_pte_t rpte;
 228         unsigned long hpte_group;
 229         unsigned long rflags, pa;
 230         unsigned long old_pte, new_pte;
 231         unsigned long vpn, hash, slot;
 232         unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;
 233
 234         /*
 235          * atomically mark the linux large page PTE busy and dirty
 236          */
 237         do {
 238                 pte_t pte = READ_ONCE(*ptep);
 239
 240                 old_pte = pte_val(pte);
 241                 /* If PTE busy, retry the access */
 242                 if (unlikely(old_pte & H_PAGE_BUSY))
 243                         return 0;
 244                 /* If PTE permissions don't match, take page fault */
 245                 if (unlikely(!check_pte_access(access, old_pte)))
 246                         return 1;
 247                 /*
 248                  * Check if PTE has the cache-inhibit bit set
 249                  * If so, bail out and refault as a 4k page
 250                  */
 251                 if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
 252                     unlikely(pte_ci(pte)))
 253                         return 0;
 254                 /*
 255                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
 256                  * a write access.
 257                  */
 258                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
 259                 if (access & _PAGE_WRITE)
 260                         new_pte |= _PAGE_DIRTY;
 261         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
 262
 263         rflags = htab_convert_pte_flags(new_pte);
 264         rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
 265
 266         if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 267             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 268                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 269
 270         vpn  = hpt_vpn(ea, vsid, ssize);
 271         if (unlikely(old_pte & H_PAGE_HASHPTE)) {
 272                 unsigned long gslot;
 273
 274                 /*
 275                  * There MIGHT be an HPTE for this pte
 276                  */
 277                 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
 278                 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
 279                                                MMU_PAGE_64K, ssize,
 280                                                flags) == -1)
 281                         old_pte &= ~_PAGE_HPTEFLAGS;
 282         }
 283
 284         if (likely(!(old_pte & H_PAGE_HASHPTE))) {
 285
 286                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 287                 hash = hpt_hash(vpn, shift, ssize);
 288
 289 repeat:
 290                 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 291
 292                 /* Insert into the hash table, primary slot */
 293                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 294                                                 MMU_PAGE_64K, MMU_PAGE_64K,
 295                                                 ssize);
 296                 /*
 297                  * Primary is full, try the secondary
 298                  */
 299                 if (unlikely(slot == -1)) {
 300                         hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
 301                         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 302                                                         rflags,
 303                                                         HPTE_V_SECONDARY,
 304                                                         MMU_PAGE_64K,
 305                                                         MMU_PAGE_64K, ssize);
 306                         if (slot == -1) {
 307                                 if (mftb() & 0x1)
 308                                         hpte_group = (hash & htab_hash_mask) *
 309                                                         HPTES_PER_GROUP;
 310                                 mmu_hash_ops.hpte_remove(hpte_group);
 311                                 /*
 312                                  * FIXME!! Should be try the group from which we removed ?
 313                                  */
 314                                 goto repeat;
 315                         }
 316                 }
 317                 /*
 318                  * Hypervisor failure. Restore old pte and return -1
 319                  * similar to __hash_page_*
 320                  */
 321                 if (unlikely(slot == -2)) {
 322                         *ptep = __pte(old_pte);
 323                         hash_failure_debug(ea, access, vsid, trap, ssize,
 324                                            MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
 325                         return -1;
 326                 }
 327
 328                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 329                 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
 330         }
 331         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 332         return 0;
 333 }