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  * index from 0 - 15
  20  */
  21 bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
  22 {
  23         unsigned long g_idx;
  24         unsigned long ptev = pte_val(rpte.pte);
  25
  26         g_idx = (ptev & H_PAGE_COMBO_VALID) >> H_PAGE_F_GIX_SHIFT;
  27         index = index >> 2;
  28         if (g_idx & (0x1 << index))
  29                 return true;
  30         else
  31                 return false;
  32 }
  33 /*
  34  * index from 0 - 15
  35  */
  36 static unsigned long mark_subptegroup_valid(unsigned long ptev, unsigned long index)
  37 {
  38         unsigned long g_idx;
  39
  40         if (!(ptev & H_PAGE_COMBO))
  41                 return ptev;
  42         index = index >> 2;
  43         g_idx = 0x1 << index;
  44
  45         return ptev | (g_idx << H_PAGE_F_GIX_SHIFT);
  46 }
  47
  48 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
  49                    pte_t *ptep, unsigned long trap, unsigned long flags,
  50                    int ssize, int subpg_prot)
  51 {
  52         real_pte_t rpte;
  53         unsigned long *hidxp;
  54         unsigned long hpte_group;
  55         unsigned int subpg_index;
  56         unsigned long rflags, pa, hidx;
  57         unsigned long old_pte, new_pte, subpg_pte;
  58         unsigned long vpn, hash, slot;
  59         unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
  60
  61         /*
  62          * atomically mark the linux large page PTE busy and dirty
  63          */
  64         do {
  65                 pte_t pte = READ_ONCE(*ptep);
  66
  67                 old_pte = pte_val(pte);
  68                 /* If PTE busy, retry the access */
  69                 if (unlikely(old_pte & H_PAGE_BUSY))
  70                         return 0;
  71                 /* If PTE permissions don't match, take page fault */
  72                 if (unlikely(!check_pte_access(access, old_pte)))
  73                         return 1;
  74                 /*
  75                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  76                  * a write access. Since this is 4K insert of 64K page size
  77                  * also add H_PAGE_COMBO
  78                  */
  79                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED | H_PAGE_COMBO;
  80                 if (access & _PAGE_WRITE)
  81                         new_pte |= _PAGE_DIRTY;
  82         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
  83
  84         /*
  85          * Handle the subpage protection bits
  86          */
  87         subpg_pte = new_pte & ~subpg_prot;
  88         rflags = htab_convert_pte_flags(subpg_pte);
  89
  90         if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
  91             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
  92
  93                 /*
  94                  * No CPU has hugepages but lacks no execute, so we
  95                  * don't need to worry about that case
  96                  */
  97                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  98         }
  99
 100         subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
 101         vpn  = hpt_vpn(ea, vsid, ssize);
 102         rpte = __real_pte(__pte(old_pte), ptep);
 103         /*
 104          *None of the sub 4k page is hashed
 105          */
 106         if (!(old_pte & H_PAGE_HASHPTE))
 107                 goto htab_insert_hpte;
 108         /*
 109          * Check if the pte was already inserted into the hash table
 110          * as a 64k HW page, and invalidate the 64k HPTE if so.
 111          */
 112         if (!(old_pte & H_PAGE_COMBO)) {
 113                 flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
 114                 /*
 115                  * clear the old slot details from the old and new pte.
 116                  * On hash insert failure we use old pte value and we don't
 117                  * want slot information there if we have a insert failure.
 118                  */
 119                 old_pte &= ~(H_PAGE_HASHPTE | H_PAGE_F_GIX | H_PAGE_F_SECOND);
 120                 new_pte &= ~(H_PAGE_HASHPTE | H_PAGE_F_GIX | H_PAGE_F_SECOND);
 121                 goto htab_insert_hpte;
 122         }
 123         /*
 124          * Check for sub page valid and update
 125          */
 126         if (__rpte_sub_valid(rpte, subpg_index)) {
 127                 int ret;
 128
 129                 hash = hpt_hash(vpn, shift, ssize);
 130                 hidx = __rpte_to_hidx(rpte, subpg_index);
 131                 if (hidx & _PTEIDX_SECONDARY)
 132                         hash = ~hash;
 133                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 134                 slot += hidx & _PTEIDX_GROUP_IX;
 135
 136                 ret = mmu_hash_ops.hpte_updatepp(slot, rflags, vpn,
 137                                                  MMU_PAGE_4K, MMU_PAGE_4K,
 138                                                  ssize, flags);
 139                 /*
 140                  *if we failed because typically the HPTE wasn't really here
 141                  * we try an insertion.
 142                  */
 143                 if (ret == -1)
 144                         goto htab_insert_hpte;
 145
 146                 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 147                 return 0;
 148         }
 149
 150 htab_insert_hpte:
 151         /*
 152          * handle H_PAGE_4K_PFN case
 153          */
 154         if (old_pte & H_PAGE_4K_PFN) {
 155                 /*
 156                  * All the sub 4k page have the same
 157                  * physical address.
 158                  */
 159                 pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
 160         } else {
 161                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 162                 pa += (subpg_index << shift);
 163         }
 164         hash = hpt_hash(vpn, shift, ssize);
 165 repeat:
 166         hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 167
 168         /* Insert into the hash table, primary slot */
 169         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 170                                         MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 171         /*
 172          * Primary is full, try the secondary
 173          */
 174         if (unlikely(slot == -1)) {
 175                 hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 176                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 177                                                 rflags, HPTE_V_SECONDARY,
 178                                                 MMU_PAGE_4K, MMU_PAGE_4K,
 179                                                 ssize);
 180                 if (slot == -1) {
 181                         if (mftb() & 0x1)
 182                                 hpte_group = ((hash & htab_hash_mask) *
 183                                               HPTES_PER_GROUP) & ~0x7UL;
 184                         mmu_hash_ops.hpte_remove(hpte_group);
 185                         /*
 186                          * FIXME!! Should be try the group from which we removed ?
 187                          */
 188                         goto repeat;
 189                 }
 190         }
 191         /*
 192          * Hypervisor failure. Restore old pte and return -1
 193          * similar to __hash_page_*
 194          */
 195         if (unlikely(slot == -2)) {
 196                 *ptep = __pte(old_pte);
 197                 hash_failure_debug(ea, access, vsid, trap, ssize,
 198                                    MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 199                 return -1;
 200         }
 201         /*
 202          * Insert slot number & secondary bit in PTE second half,
 203          * clear H_PAGE_BUSY and set appropriate HPTE slot bit
 204          * Since we have H_PAGE_BUSY set on ptep, we can be sure
 205          * nobody is undating hidx.
 206          */
 207         hidxp = (unsigned long *)(ptep + PTRS_PER_PTE);
 208         rpte.hidx &= ~(0xfUL << (subpg_index << 2));
 209         *hidxp = rpte.hidx  | (slot << (subpg_index << 2));
 210         new_pte = mark_subptegroup_valid(new_pte, subpg_index);
 211         new_pte |=  H_PAGE_HASHPTE;
 212         /*
 213          * check __real_pte for details on matching smp_rmb()
 214          */
 215         smp_wmb();
 216         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 217         return 0;
 218 }
 219
 220 int __hash_page_64K(unsigned long ea, unsigned long access,
 221                     unsigned long vsid, pte_t *ptep, unsigned long trap,
 222                     unsigned long flags, int ssize)
 223 {
 224         unsigned long hpte_group;
 225         unsigned long rflags, pa;
 226         unsigned long old_pte, new_pte;
 227         unsigned long vpn, hash, slot;
 228         unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;
 229
 230         /*
 231          * atomically mark the linux large page PTE busy and dirty
 232          */
 233         do {
 234                 pte_t pte = READ_ONCE(*ptep);
 235
 236                 old_pte = pte_val(pte);
 237                 /* If PTE busy, retry the access */
 238                 if (unlikely(old_pte & H_PAGE_BUSY))
 239                         return 0;
 240                 /* If PTE permissions don't match, take page fault */
 241                 if (unlikely(!check_pte_access(access, old_pte)))
 242                         return 1;
 243                 /*
 244                  * Check if PTE has the cache-inhibit bit set
 245                  * If so, bail out and refault as a 4k page
 246                  */
 247                 if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
 248                     unlikely(pte_ci(pte)))
 249                         return 0;
 250                 /*
 251                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
 252                  * a write access.
 253                  */
 254                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
 255                 if (access & _PAGE_WRITE)
 256                         new_pte |= _PAGE_DIRTY;
 257         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
 258
 259         rflags = htab_convert_pte_flags(new_pte);
 260
 261         if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 262             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 263                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 264
 265         vpn  = hpt_vpn(ea, vsid, ssize);
 266         if (unlikely(old_pte & H_PAGE_HASHPTE)) {
 267                 /*
 268                  * There MIGHT be an HPTE for this pte
 269                  */
 270                 hash = hpt_hash(vpn, shift, ssize);
 271                 if (old_pte & H_PAGE_F_SECOND)
 272                         hash = ~hash;
 273                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 274                 slot += (old_pte & H_PAGE_F_GIX) >> H_PAGE_F_GIX_SHIFT;
 275
 276                 if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_64K,
 277                                                MMU_PAGE_64K, ssize,
 278                                                flags) == -1)
 279                         old_pte &= ~_PAGE_HPTEFLAGS;
 280         }
 281
 282         if (likely(!(old_pte & H_PAGE_HASHPTE))) {
 283
 284                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 285                 hash = hpt_hash(vpn, shift, ssize);
 286
 287 repeat:
 288                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 289
 290                 /* Insert into the hash table, primary slot */
 291                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 292                                                 MMU_PAGE_64K, MMU_PAGE_64K,
 293                                                 ssize);
 294                 /*
 295                  * Primary is full, try the secondary
 296                  */
 297                 if (unlikely(slot == -1)) {
 298                         hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 299                         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 300                                                         rflags,
 301                                                         HPTE_V_SECONDARY,
 302                                                         MMU_PAGE_64K,
 303                                                         MMU_PAGE_64K, ssize);
 304                         if (slot == -1) {
 305                                 if (mftb() & 0x1)
 306                                         hpte_group = ((hash & htab_hash_mask) *
 307                                                       HPTES_PER_GROUP) & ~0x7UL;
 308                                 mmu_hash_ops.hpte_remove(hpte_group);
 309                                 /*
 310                                  * FIXME!! Should be try the group from which we removed ?
 311                                  */
 312                                 goto repeat;
 313                         }
 314                 }
 315                 /*
 316                  * Hypervisor failure. Restore old pte and return -1
 317                  * similar to __hash_page_*
 318                  */
 319                 if (unlikely(slot == -2)) {
 320                         *ptep = __pte(old_pte);
 321                         hash_failure_debug(ea, access, vsid, trap, ssize,
 322                                            MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
 323                         return -1;
 324                 }
 325                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 326                 new_pte |= (slot << H_PAGE_F_GIX_SHIFT) &
 327                         (H_PAGE_F_SECOND | H_PAGE_F_GIX);
 328         }
 329         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 330         return 0;
 331 }