LXR linux/arch/powerpc/mm/hash64

   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
  19int __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, PTRS_PER_PTE);
  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
  82repeat:
  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, PTRS_PER_PTE);
 121        }
 122        *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 123        return 0;
 124}
 125