LXR linux/arch/powerpc/mm/hugetlbpage-hash64.c

   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
  17extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
  18                                  unsigned long pa, unsigned long rlags,
  19                                  unsigned long vflags, int psize, int ssize);
  20
  21int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
  22                     pte_t *ptep, unsigned long trap, unsigned long flags,
  23                     int ssize, unsigned int shift, unsigned int mmu_psize)
  24{
  25        unsigned long vpn;
  26        unsigned long old_pte, new_pte;
  27        unsigned long rflags, pa, sz;
  28        long slot;
  29
  30        BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
  31
  32        /* Search the Linux page table for a match with va */
  33        vpn = hpt_vpn(ea, vsid, ssize);
  34
  35        /* At this point, we have a pte (old_pte) which can be used to build
  36         * or update an HPTE. There are 2 cases:
  37         *
  38         * 1. There is a valid (present) pte with no associated HPTE (this is
  39         *      the most common case)
  40         * 2. There is a valid (present) pte with an associated HPTE. The
  41         *      current values of the pp bits in the HPTE prevent access
  42         *      because we are doing software DIRTY bit management and the
  43         *      page is currently not DIRTY.
  44         */
  45
  46
  47        do {
  48                old_pte = pte_val(*ptep);
  49                /* If PTE busy, retry the access */
  50                if (unlikely(old_pte & H_PAGE_BUSY))
  51                        return 0;
  52                /* If PTE permissions don't match, take page fault */
  53                if (unlikely(!check_pte_access(access, old_pte)))
  54                        return 1;
  55
  56                /* Try to lock the PTE, add ACCESSED and DIRTY if it was
  57                 * a write access */
  58                new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
  59                if (access & _PAGE_WRITE)
  60                        new_pte |= _PAGE_DIRTY;
  61        } while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
  62
  63        rflags = htab_convert_pte_flags(new_pte);
  64
  65        sz = ((1UL) << shift);
  66        if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  67                /* No CPU has hugepages but lacks no execute, so we
  68                 * don't need to worry about that case */
  69                rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  70
  71        /* Check if pte already has an hpte (case 2) */
  72        if (unlikely(old_pte & H_PAGE_HASHPTE)) {
  73                /* There MIGHT be an HPTE for this pte */
  74                unsigned long hash, slot;
  75
  76                hash = hpt_hash(vpn, shift, ssize);
  77                if (old_pte & H_PAGE_F_SECOND)
  78                        hash = ~hash;
  79                slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  80                slot += (old_pte & H_PAGE_F_GIX) >> H_PAGE_F_GIX_SHIFT;
  81
  82                if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, mmu_psize,
  83                                               mmu_psize, ssize, flags) == -1)
  84                        old_pte &= ~_PAGE_HPTEFLAGS;
  85        }
  86
  87        if (likely(!(old_pte & H_PAGE_HASHPTE))) {
  88                unsigned long hash = hpt_hash(vpn, shift, ssize);
  89
  90                pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  91
  92                /* clear HPTE slot informations in new PTE */
  93                new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
  94
  95                slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
  96                                             mmu_psize, ssize);
  97
  98                /*
  99                 * Hypervisor failure. Restore old pte and return -1
 100                 * similar to __hash_page_*
 101                 */
 102                if (unlikely(slot == -2)) {
 103                        *ptep = __pte(old_pte);
 104                        hash_failure_debug(ea, access, vsid, trap, ssize,
 105                                           mmu_psize, mmu_psize, old_pte);
 106                        return -1;
 107                }
 108
 109                new_pte |= (slot << H_PAGE_F_GIX_SHIFT) &
 110                        (H_PAGE_F_SECOND | H_PAGE_F_GIX);
 111        }
 112
 113        /*
 114         * No need to use ldarx/stdcx here
 115         */
 116        *ptep = __pte(new_pte & ~H_PAGE_BUSY);
 117        return 0;
 118}
 119
 120#if defined(CONFIG_PPC_64K_PAGES) && defined(CONFIG_DEBUG_VM)
 121/*
 122 * This enables us to catch the wrong page directory format
 123 * Moved here so that we can use WARN() in the call.
 124 */
 125int hugepd_ok(hugepd_t hpd)
 126{
 127        bool is_hugepd;
 128
 129        /*
 130         * We should not find this format in page directory, warn otherwise.
 131         */
 132        is_hugepd = (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
 133        WARN(is_hugepd, "Found wrong page directory format\n");
 134        return 0;
 135}
 136#endif
 137