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
  17 int __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
  89 repeat:
  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 }