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