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 extern 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
  21 int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
  22                      pte_t *ptep, unsigned long trap, int local, int ssize,
  23                      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 & _PAGE_BUSY))
  51                         return 0;
  52                 /* If PTE permissions don't match, take page fault */
  53                 if (unlikely(access & ~old_pte))
  54                         return 1;
  55                 /* Try to lock the PTE, add ACCESSED and DIRTY if it was
  56                  * a write access */
  57                 new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
  58                 if (access & _PAGE_RW)
  59                         new_pte |= _PAGE_DIRTY;
  60         } while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
  61                                          old_pte, new_pte));
  62
  63         rflags = 0x2 | (!(new_pte & _PAGE_RW));
  64         /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
  65         rflags |= ((new_pte & _PAGE_EXEC) ? 0 : HPTE_R_N);
  66         sz = ((1UL) << shift);
  67         if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
  68                 /* No CPU has hugepages but lacks no execute, so we
  69                  * don't need to worry about that case */
  70                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
  71
  72         /* Check if pte already has an hpte (case 2) */
  73         if (unlikely(old_pte & _PAGE_HASHPTE)) {
  74                 /* There MIGHT be an HPTE for this pte */
  75                 unsigned long hash, slot;
  76
  77                 hash = hpt_hash(vpn, shift, ssize);
  78                 if (old_pte & _PAGE_F_SECOND)
  79                         hash = ~hash;
  80                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  81                 slot += (old_pte & _PAGE_F_GIX) >> 12;
  82
  83                 if (ppc_md.hpte_updatepp(slot, rflags, vpn, mmu_psize,
  84                                          mmu_psize, ssize, local) == -1)
  85                         old_pte &= ~_PAGE_HPTEFLAGS;
  86         }
  87
  88         if (likely(!(old_pte & _PAGE_HASHPTE))) {
  89                 unsigned long hash = hpt_hash(vpn, shift, ssize);
  90
  91                 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
  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                 slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
 104                                              mmu_psize, ssize);
 105
 106                 /*
 107                  * Hypervisor failure. Restore old pte and return -1
 108                  * similar to __hash_page_*
 109                  */
 110                 if (unlikely(slot == -2)) {
 111                         *ptep = __pte(old_pte);
 112                         hash_failure_debug(ea, access, vsid, trap, ssize,
 113                                            mmu_psize, mmu_psize, old_pte);
 114                         return -1;
 115                 }
 116
 117                 new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
 118         }
 119
 120         /*
 121          * No need to use ldarx/stdcx here
 122          */
 123         *ptep = __pte(new_pte & ~_PAGE_BUSY);
 124         return 0;
 125 }