arch/powerpc/mm/hash64_4k.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 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
  20                    pte_t *ptep, unsigned long trap, unsigned long flags,
  21                    int ssize, int subpg_prot)
  22 {
  23         real_pte_t rpte;
  24         unsigned long hpte_group;
  25         unsigned long rflags, pa;
  26         unsigned long old_pte, new_pte;
  27         unsigned long vpn, hash, slot;
  28         unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
  29
  30         /*
  31          * atomically mark the linux large page PTE busy and dirty
  32          */
  33         do {
  34                 pte_t pte = READ_ONCE(*ptep);
  35
  36                 old_pte = pte_val(pte);
  37                 /* If PTE busy, retry the access */
  38                 if (unlikely(old_pte & H_PAGE_BUSY))
  39                         return 0;
  40                 /* If PTE permissions don't match, take page fault */
  41                 if (unlikely(!check_pte_access(access, old_pte)))
  42                         return 1;
  43                 /*
  44                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  45                  * a write access. Since this is 4K insert of 64K page size
  46                  * also add H_PAGE_COMBO
  47                  */
  48                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
  49                 if (access & _PAGE_WRITE)
  50                         new_pte |= _PAGE_DIRTY;
  51         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
  52
  53         /*
  54          * PP bits. _PAGE_USER is already PP bit 0x2, so we only
  55          * need to add in 0x1 if it's a read-only user page
  56          */
  57         rflags = htab_convert_pte_flags(new_pte);
  58         rpte = __real_pte(__pte(old_pte), ptep);
  59
  60         if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
  61             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  62                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  63
  64         vpn  = hpt_vpn(ea, vsid, ssize);
  65         if (unlikely(old_pte & H_PAGE_HASHPTE)) {
  66                 /*
  67                  * There MIGHT be an HPTE for this pte
  68                  */
  69                 unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
  70                                                          rpte, 0);
  71
  72                 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
  73                                                MMU_PAGE_4K, ssize, flags) == -1)
  74                         old_pte &= ~_PAGE_HPTEFLAGS;
  75         }
  76
  77         if (likely(!(old_pte & H_PAGE_HASHPTE))) {
  78
  79                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  80                 hash = hpt_hash(vpn, shift, ssize);
  81
  82 repeat:
  83                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
  84
  85                 /* Insert into the hash table, primary slot */
  86                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
  87                                                 MMU_PAGE_4K, MMU_PAGE_4K, ssize);
  88                 /*
  89                  * Primary is full, try the secondary
  90                  */
  91                 if (unlikely(slot == -1)) {
  92                         hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
  93                         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
  94                                                         rflags,
  95                                                         HPTE_V_SECONDARY,
  96                                                         MMU_PAGE_4K,
  97                                                         MMU_PAGE_4K, ssize);
  98                         if (slot == -1) {
  99                                 if (mftb() & 0x1)
 100                                         hpte_group = ((hash & htab_hash_mask) *
 101                                                       HPTES_PER_GROUP) & ~0x7UL;
 102                                 mmu_hash_ops.hpte_remove(hpte_group);
 103                                 /*
 104                                  * FIXME!! Should be try the group from which we removed ?
 105                                  */
 106                                 goto repeat;
 107                         }
 108                 }
 109                 /*
 110                  * Hypervisor failure. Restore old pte and return -1
 111                  * similar to __hash_page_*
 112                  */
 113                 if (unlikely(slot == -2)) {
 114                         *ptep = __pte(old_pte);
 115                         hash_failure_debug(ea, access, vsid, trap, ssize,
 116                                            MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 117                         return -1;
 118                 }
 119                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 120                 new_pte |= pte_set_hidx(ptep, rpte, 0, slot);
 121         }
 122         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 123         return 0;
 124 }