linux/arch/powerpc/mm/hugetlbpage-hash64.c
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   1/*
   2 * PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later)
   3 *
   4 * Copyright (C) 2003 David Gibson, IBM Corporation.
   5 *
   6 * Based on the IA-32 version:
   7 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
   8 */
   9
  10#include <linux/mm.h>
  11#include <linux/hugetlb.h>
  12#include <asm/pgtable.h>
  13#include <asm/pgalloc.h>
  14#include <asm/cacheflush.h>
  15#include <asm/machdep.h>
  16
  17int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
  18                     pte_t *ptep, unsigned long trap, int local, int ssize,
  19                     unsigned int shift, unsigned int mmu_psize)
  20{
  21        unsigned long old_pte, new_pte;
  22        unsigned long va, rflags, pa, sz;
  23        long slot;
  24
  25        BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
  26
  27        /* Search the Linux page table for a match with va */
  28        va = hpt_va(ea, vsid, ssize);
  29
  30        /* At this point, we have a pte (old_pte) which can be used to build
  31         * or update an HPTE. There are 2 cases:
  32         *
  33         * 1. There is a valid (present) pte with no associated HPTE (this is
  34         *      the most common case)
  35         * 2. There is a valid (present) pte with an associated HPTE. The
  36         *      current values of the pp bits in the HPTE prevent access
  37         *      because we are doing software DIRTY bit management and the
  38         *      page is currently not DIRTY.
  39         */
  40
  41
  42        do {
  43                old_pte = pte_val(*ptep);
  44                /* If PTE busy, retry the access */
  45                if (unlikely(old_pte & _PAGE_BUSY))
  46                        return 0;
  47                /* If PTE permissions don't match, take page fault */
  48                if (unlikely(access & ~old_pte))
  49                        return 1;
  50                /* Try to lock the PTE, add ACCESSED and DIRTY if it was
  51                 * a write access */
  52                new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
  53                if (access & _PAGE_RW)
  54                        new_pte |= _PAGE_DIRTY;
  55        } while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
  56                                         old_pte, new_pte));
  57
  58        rflags = 0x2 | (!(new_pte & _PAGE_RW));
  59        /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
  60        rflags |= ((new_pte & _PAGE_EXEC) ? 0 : HPTE_R_N);
  61        sz = ((1UL) << shift);
  62        if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  63                /* No CPU has hugepages but lacks no execute, so we
  64                 * don't need to worry about that case */
  65                rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  66
  67        /* Check if pte already has an hpte (case 2) */
  68        if (unlikely(old_pte & _PAGE_HASHPTE)) {
  69                /* There MIGHT be an HPTE for this pte */
  70                unsigned long hash, slot;
  71
  72                hash = hpt_hash(va, shift, ssize);
  73                if (old_pte & _PAGE_F_SECOND)
  74                        hash = ~hash;
  75                slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  76                slot += (old_pte & _PAGE_F_GIX) >> 12;
  77
  78                if (ppc_md.hpte_updatepp(slot, rflags, va, mmu_psize,
  79                                         ssize, local) == -1)
  80                        old_pte &= ~_PAGE_HPTEFLAGS;
  81        }
  82
  83        if (likely(!(old_pte & _PAGE_HASHPTE))) {
  84                unsigned long hash = hpt_hash(va, shift, ssize);
  85                unsigned long hpte_group;
  86
  87                pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  88
  89repeat:
  90                hpte_group = ((hash & htab_hash_mask) *
  91                              HPTES_PER_GROUP) & ~0x7UL;
  92
  93                /* clear HPTE slot informations in new PTE */
  94#ifdef CONFIG_PPC_64K_PAGES
  95                new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HPTE_SUB0;
  96#else
  97                new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
  98#endif
  99                /* Add in WIMG bits */
 100                rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
 101                                      _PAGE_COHERENT | _PAGE_GUARDED));
 102
 103                /* Insert into the hash table, primary slot */
 104                slot = ppc_md.hpte_insert(hpte_group, va, pa, rflags, 0,
 105                                          mmu_psize, ssize);
 106
 107                /* Primary is full, try the secondary */
 108                if (unlikely(slot == -1)) {
 109                        hpte_group = ((~hash & htab_hash_mask) *
 110                                      HPTES_PER_GROUP) & ~0x7UL;
 111                        slot = ppc_md.hpte_insert(hpte_group, va, pa, rflags,
 112                                                  HPTE_V_SECONDARY,
 113                                                  mmu_psize, ssize);
 114                        if (slot == -1) {
 115                                if (mftb() & 0x1)
 116                                        hpte_group = ((hash & htab_hash_mask) *
 117                                                      HPTES_PER_GROUP)&~0x7UL;
 118
 119                                ppc_md.hpte_remove(hpte_group);
 120                                goto repeat;
 121                        }
 122                }
 123
 124                /*
 125                 * Hypervisor failure. Restore old pte and return -1
 126                 * similar to __hash_page_*
 127                 */
 128                if (unlikely(slot == -2)) {
 129                        *ptep = __pte(old_pte);
 130                        hash_failure_debug(ea, access, vsid, trap, ssize,
 131                                           mmu_psize, old_pte);
 132                        return -1;
 133                }
 134
 135                new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
 136        }
 137
 138        /*
 139         * No need to use ldarx/stdcx here
 140         */
 141        *ptep = __pte(new_pte & ~_PAGE_BUSY);
 142        return 0;
 143}
 144