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         unsigned long hpte_group;
  24         unsigned long rflags, pa;
  25         unsigned long old_pte, new_pte;
  26         unsigned long vpn, hash, slot;
  27         unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
  28
  29         /*
  30          * atomically mark the linux large page PTE busy and dirty
  31          */
  32         do {
  33                 pte_t pte = READ_ONCE(*ptep);
  34
  35                 old_pte = pte_val(pte);
  36                 /* If PTE busy, retry the access */
  37                 if (unlikely(old_pte & _PAGE_BUSY))
  38                         return 0;
  39                 /* If PTE permissions don't match, take page fault */
  40                 if (unlikely(access & ~old_pte))
  41                         return 1;
  42                 /*
  43                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
  44                  * a write access. Since this is 4K insert of 64K page size
  45                  * also add _PAGE_COMBO
  46                  */
  47                 new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
  48                 if (access & _PAGE_RW)
  49                         new_pte |= _PAGE_DIRTY;
  50         } while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
  51                                           old_pte, new_pte));
  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 = htab_convert_pte_flags(new_pte);
  57
  58         if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
  59             !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  60                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  61
  62         vpn  = hpt_vpn(ea, vsid, ssize);
  63         if (unlikely(old_pte & _PAGE_HASHPTE)) {
  64                 /*
  65                  * There MIGHT be an HPTE for this pte
  66                  */
  67                 hash = hpt_hash(vpn, shift, ssize);
  68                 if (old_pte & _PAGE_F_SECOND)
  69                         hash = ~hash;
  70                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  71                 slot += (old_pte & _PAGE_F_GIX) >> _PAGE_F_GIX_SHIFT;
  72
  73                 if (ppc_md.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_4K,
  74                                          MMU_PAGE_4K, ssize, flags) == -1)
  75                         old_pte &= ~_PAGE_HPTEFLAGS;
  76         }
  77
  78         if (likely(!(old_pte & _PAGE_HASHPTE))) {
  79
  80                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  81                 hash = hpt_hash(vpn, shift, ssize);
  82
  83 repeat:
  84                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
  85
  86                 /* Insert into the hash table, primary slot */
  87                 slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
  88                                   MMU_PAGE_4K, MMU_PAGE_4K, ssize);
  89                 /*
  90                  * Primary is full, try the secondary
  91                  */
  92                 if (unlikely(slot == -1)) {
  93                         hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
  94                         slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
  95                                                   rflags, HPTE_V_SECONDARY,
  96                                                   MMU_PAGE_4K, MMU_PAGE_4K, ssize);
  97                         if (slot == -1) {
  98                                 if (mftb() & 0x1)
  99                                         hpte_group = ((hash & htab_hash_mask) *
 100                                                       HPTES_PER_GROUP) & ~0x7UL;
 101                                 ppc_md.hpte_remove(hpte_group);
 102                                 /*
 103                                  * FIXME!! Should be try the group from which we removed ?
 104                                  */
 105                                 goto repeat;
 106                         }
 107                 }
 108                 /*
 109                  * Hypervisor failure. Restore old pte and return -1
 110                  * similar to __hash_page_*
 111                  */
 112                 if (unlikely(slot == -2)) {
 113                         *ptep = __pte(old_pte);
 114                         hash_failure_debug(ea, access, vsid, trap, ssize,
 115                                            MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 116                         return -1;
 117                 }
 118                 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
 119                 new_pte |= (slot << _PAGE_F_GIX_SHIFT) & (_PAGE_F_SECOND | _PAGE_F_GIX);
 120         }
 121         *ptep = __pte(new_pte & ~_PAGE_BUSY);
 122         return 0;
 123 }