arch/powerpc/mm/hugepage-hash64.c

   1 /*
   2  * Copyright IBM Corporation, 2013
   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 2.1 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 /*
  16  * PPC64 THP Support for hash based MMUs
  17  */
  18 #include <linux/mm.h>
  19 #include <asm/machdep.h>
  20
  21 int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
  22                     pmd_t *pmdp, unsigned long trap, int local, int ssize,
  23                     unsigned int psize)
  24 {
  25         unsigned int index, valid;
  26         unsigned char *hpte_slot_array;
  27         unsigned long rflags, pa, hidx;
  28         unsigned long old_pmd, new_pmd;
  29         int ret, lpsize = MMU_PAGE_16M;
  30         unsigned long vpn, hash, shift, slot;
  31
  32         /*
  33          * atomically mark the linux large page PMD busy and dirty
  34          */
  35         do {
  36                 old_pmd = pmd_val(*pmdp);
  37                 /* If PMD busy, retry the access */
  38                 if (unlikely(old_pmd & _PAGE_BUSY))
  39                         return 0;
  40                 /* If PMD is trans splitting retry the access */
  41                 if (unlikely(old_pmd & _PAGE_SPLITTING))
  42                         return 0;
  43                 /* If PMD permissions don't match, take page fault */
  44                 if (unlikely(access & ~old_pmd))
  45                         return 1;
  46                 /*
  47                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  48                  * a write access
  49                  */
  50                 new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
  51                 if (access & _PAGE_RW)
  52                         new_pmd |= _PAGE_DIRTY;
  53         } while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
  54                                           old_pmd, new_pmd));
  55         /*
  56          * PP bits. _PAGE_USER is already PP bit 0x2, so we only
  57          * need to add in 0x1 if it's a read-only user page
  58          */
  59         rflags = new_pmd & _PAGE_USER;
  60         if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
  61                                            (new_pmd & _PAGE_DIRTY)))
  62                 rflags |= 0x1;
  63         /*
  64          * _PAGE_EXEC -> HW_NO_EXEC since it's inverted
  65          */
  66         rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
  67
  68 #if 0
  69         if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
  70
  71                 /*
  72                  * No CPU has hugepages but lacks no execute, so we
  73                  * don't need to worry about that case
  74                  */
  75                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  76         }
  77 #endif
  78         /*
  79          * Find the slot index details for this ea, using base page size.
  80          */
  81         shift = mmu_psize_defs[psize].shift;
  82         index = (ea & ~HPAGE_PMD_MASK) >> shift;
  83         BUG_ON(index >= 4096);
  84
  85         vpn = hpt_vpn(ea, vsid, ssize);
  86         hash = hpt_hash(vpn, shift, ssize);
  87         hpte_slot_array = get_hpte_slot_array(pmdp);
  88
  89         valid = hpte_valid(hpte_slot_array, index);
  90         if (valid) {
  91                 /* update the hpte bits */
  92                 hidx =  hpte_hash_index(hpte_slot_array, index);
  93                 if (hidx & _PTEIDX_SECONDARY)
  94                         hash = ~hash;
  95                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  96                 slot += hidx & _PTEIDX_GROUP_IX;
  97
  98                 ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
  99                                            psize, lpsize, ssize, local);
 100                 /*
 101                  * We failed to update, try to insert a new entry.
 102                  */
 103                 if (ret == -1) {
 104                         /*
 105                          * large pte is marked busy, so we can be sure
 106                          * nobody is looking at hpte_slot_array. hence we can
 107                          * safely update this here.
 108                          */
 109                         valid = 0;
 110                         new_pmd &= ~_PAGE_HPTEFLAGS;
 111                         hpte_slot_array[index] = 0;
 112                 } else
 113                         /* clear the busy bits and set the hash pte bits */
 114                         new_pmd = (new_pmd & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
 115         }
 116
 117         if (!valid) {
 118                 unsigned long hpte_group;
 119
 120                 /* insert new entry */
 121                 pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
 122 repeat:
 123                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 124
 125                 /* clear the busy bits and set the hash pte bits */
 126                 new_pmd = (new_pmd & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
 127
 128                 /* Add in WIMG bits */
 129                 rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
 130                                       _PAGE_GUARDED));
 131                 /*
 132                  * enable the memory coherence always
 133                  */
 134                 rflags |= HPTE_R_M;
 135
 136                 /* Insert into the hash table, primary slot */
 137                 slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 138                                           psize, lpsize, ssize);
 139                 /*
 140                  * Primary is full, try the secondary
 141                  */
 142                 if (unlikely(slot == -1)) {
 143                         hpte_group = ((~hash & htab_hash_mask) *
 144                                       HPTES_PER_GROUP) & ~0x7UL;
 145                         slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
 146                                                   rflags, HPTE_V_SECONDARY,
 147                                                   psize, lpsize, ssize);
 148                         if (slot == -1) {
 149                                 if (mftb() & 0x1)
 150                                         hpte_group = ((hash & htab_hash_mask) *
 151                                                       HPTES_PER_GROUP) & ~0x7UL;
 152
 153                                 ppc_md.hpte_remove(hpte_group);
 154                                 goto repeat;
 155                         }
 156                 }
 157                 /*
 158                  * Hypervisor failure. Restore old pmd and return -1
 159                  * similar to __hash_page_*
 160                  */
 161                 if (unlikely(slot == -2)) {
 162                         *pmdp = __pmd(old_pmd);
 163                         hash_failure_debug(ea, access, vsid, trap, ssize,
 164                                            psize, lpsize, old_pmd);
 165                         return -1;
 166                 }
 167                 /*
 168                  * large pte is marked busy, so we can be sure
 169                  * nobody is looking at hpte_slot_array. hence we can
 170                  * safely update this here.
 171                  */
 172                 mark_hpte_slot_valid(hpte_slot_array, index, slot);
 173         }
 174         /*
 175          * No need to use ldarx/stdcx here
 176          */
 177         *pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
 178         return 0;
 179 }