arch/powerpc/mm/book3s64/hash_4k.c

   1 /*
   2  * Copyright IBM Corporation, 2015
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.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 #include "internal.h"
  20
  21 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
  22                    pte_t *ptep, unsigned long trap, unsigned long flags,
  23                    int ssize, int subpg_prot)
  24 {
  25         real_pte_t rpte;
  26         unsigned long hpte_group;
  27         unsigned long rflags, pa;
  28         unsigned long old_pte, new_pte;
  29         unsigned long vpn, hash, slot;
  30         unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
  31
  32         /*
  33          * atomically mark the linux large page PTE busy and dirty
  34          */
  35         do {
  36                 pte_t pte = READ_ONCE(*ptep);
  37
  38                 old_pte = pte_val(pte);
  39                 /* If PTE busy, retry the access */
  40                 if (unlikely(old_pte & H_PAGE_BUSY))
  41                         return 0;
  42                 /* If PTE permissions don't match, take page fault */
  43                 if (unlikely(!check_pte_access(access, old_pte)))
  44                         return 1;
  45                 /*
  46                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  47                  * a write access. Since this is 4K insert of 64K page size
  48                  * also add H_PAGE_COMBO
  49                  */
  50                 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
  51                 if (access & _PAGE_WRITE)
  52                         new_pte |= _PAGE_DIRTY;
  53         } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
  54
  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 = htab_convert_pte_flags(new_pte, flags);
  60         rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
  61
  62         if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
  63             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  64                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  65
  66         vpn  = hpt_vpn(ea, vsid, ssize);
  67         if (unlikely(old_pte & H_PAGE_HASHPTE)) {
  68                 /*
  69                  * There MIGHT be an HPTE for this pte
  70                  */
  71                 unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
  72                                                          rpte, 0);
  73
  74                 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
  75                                                MMU_PAGE_4K, ssize, flags) == -1)
  76                         old_pte &= ~_PAGE_HPTEFLAGS;
  77         }
  78
  79         if (likely(!(old_pte & H_PAGE_HASHPTE))) {
  80
  81                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  82                 hash = hpt_hash(vpn, shift, ssize);
  83
  84 repeat:
  85                 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  86
  87                 /* Insert into the hash table, primary slot */
  88                 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
  89                                                 MMU_PAGE_4K, MMU_PAGE_4K, ssize);
  90                 /*
  91                  * Primary is full, try the secondary
  92                  */
  93                 if (unlikely(slot == -1)) {
  94                         hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
  95                         slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
  96                                                         rflags,
  97                                                         HPTE_V_SECONDARY,
  98                                                         MMU_PAGE_4K,
  99                                                         MMU_PAGE_4K, ssize);
 100                         if (slot == -1) {
 101                                 if (mftb() & 0x1)
 102                                         hpte_group = (hash & htab_hash_mask) *
 103                                                         HPTES_PER_GROUP;
 104                                 mmu_hash_ops.hpte_remove(hpte_group);
 105                                 /*
 106                                  * FIXME!! Should be try the group from which we removed ?
 107                                  */
 108                                 goto repeat;
 109                         }
 110                 }
 111                 /*
 112                  * Hypervisor failure. Restore old pte and return -1
 113                  * similar to __hash_page_*
 114                  */
 115                 if (unlikely(slot == -2)) {
 116                         *ptep = __pte(old_pte);
 117                         hash_failure_debug(ea, access, vsid, trap, ssize,
 118                                            MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 119                         return -1;
 120                 }
 121                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 122                 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
 123
 124                 if (stress_hpt())
 125                         hpt_do_stress(ea, hpte_group);
 126         }
 127         *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 128         return 0;
 129 }