arch/powerpc/mm/hash64_64k.c

   1 /*
   2  * Copyright IBM Corporation, 2015
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.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) & ~0x7UL;
 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) & ~0x7UL;
 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) *
 197                                               HPTES_PER_GROUP) & ~0x7UL;
 198
 199                         mmu_hash_ops.hpte_remove(hpte_group);
 200                         /*
 201                          * FIXME!! Should be try the group from which we removed ?
 202                          */
 203                         goto repeat;
 204                 }
 205         }
 206         /*
 207          * Hypervisor failure. Restore old pte and return -1
 208          * similar to __hash_page_*
 209          */
 210         if (unlikely(slot == -2)) {
 211                 *ptep = __pte(old_pte);
 212                 hash_failure_debug(ea, access, vsid, trap, ssize,
 213                                    MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 214                 return -1;
 215         }
 216
 217         new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
 218         new_pte |= H_PAGE_HASHPTE;
 219
 220         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 221         return 0;
 222 }
 223
 224 int __hash_page_64K(unsigned long ea, unsigned long access,
 225                     unsigned long vsid, pte_t *ptep, unsigned long trap,
 226                     unsigned long flags, int ssize)
 227 {
 228         real_pte_t rpte;
 229         unsigned long hpte_group;
 230         unsigned long rflags, pa;
 231         unsigned long old_pte, new_pte;
 232         unsigned long vpn, hash, slot;
 233         unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;
 234
 235         /*
 236          * atomically mark the linux large page PTE busy and dirty
 237          */
 238         do {
 239                 pte_t pte = READ_ONCE(*ptep);
 240
 241                 old_pte = pte_val(pte);
 242                 /* If PTE busy, retry the access */
 243                 if (unlikely(old_pte & H_PAGE_BUSY))
 244                         return 0;
 245                 /* If PTE permissions don't match, take page fault */
 246                 if (unlikely(!check_pte_access(access, old_pte)))
 247                         return 1;
 248                 /*
 249                  * Check if PTE has the cache-inhibit bit set
 250                  * If so, bail out and refault as a 4k page
 251                  */
 252                 if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
 253                     unlikely(pte_ci(pte)))
 254                         return 0;
 255                 /*
 256                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
 257                  * a write access.
 258                  */
 259                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
 260                 if (access & _PAGE_WRITE)
 261                         new_pte |= _PAGE_DIRTY;
 262         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
 263
 264         rflags = htab_convert_pte_flags(new_pte);
 265         rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
 266
 267         if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 268             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 269                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 270
 271         vpn  = hpt_vpn(ea, vsid, ssize);
 272         if (unlikely(old_pte & H_PAGE_HASHPTE)) {
 273                 unsigned long gslot;
 274
 275                 /*
 276                  * There MIGHT be an HPTE for this pte
 277                  */
 278                 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
 279                 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
 280                                                MMU_PAGE_64K, ssize,
 281                                                flags) == -1)
 282                         old_pte &= ~_PAGE_HPTEFLAGS;
 283         }
 284
 285         if (likely(!(old_pte & H_PAGE_HASHPTE))) {
 286
 287                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 288                 hash = hpt_hash(vpn, shift, ssize);
 289
 290 repeat:
 291                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 292
 293                 /* Insert into the hash table, primary slot */
 294                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 295                                                 MMU_PAGE_64K, MMU_PAGE_64K,
 296                                                 ssize);
 297                 /*
 298                  * Primary is full, try the secondary
 299                  */
 300                 if (unlikely(slot == -1)) {
 301                         hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 302                         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 303                                                         rflags,
 304                                                         HPTE_V_SECONDARY,
 305                                                         MMU_PAGE_64K,
 306                                                         MMU_PAGE_64K, ssize);
 307                         if (slot == -1) {
 308                                 if (mftb() & 0x1)
 309                                         hpte_group = ((hash & htab_hash_mask) *
 310                                                       HPTES_PER_GROUP) & ~0x7UL;
 311                                 mmu_hash_ops.hpte_remove(hpte_group);
 312                                 /*
 313                                  * FIXME!! Should be try the group from which we removed ?
 314                                  */
 315                                 goto repeat;
 316                         }
 317                 }
 318                 /*
 319                  * Hypervisor failure. Restore old pte and return -1
 320                  * similar to __hash_page_*
 321                  */
 322                 if (unlikely(slot == -2)) {
 323                         *ptep = __pte(old_pte);
 324                         hash_failure_debug(ea, access, vsid, trap, ssize,
 325                                            MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
 326                         return -1;
 327                 }
 328
 329                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 330                 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
 331         }
 332         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 333         return 0;
 334 }