arch/powerpc/mm/hugepage-hash64.c

   1 /*
   2  * Copyright IBM Corporation, 2013
   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 2.1 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 /*
  16  * PPC64 THP Support for hash based MMUs
  17  */
  18 #include <linux/mm.h>
  19 #include <asm/machdep.h>
  20
  21 static void invalidate_old_hpte(unsigned long vsid, unsigned long addr,
  22                                 pmd_t *pmdp, unsigned int psize, int ssize)
  23 {
  24         int i, max_hpte_count, valid;
  25         unsigned long s_addr;
  26         unsigned char *hpte_slot_array;
  27         unsigned long hidx, shift, vpn, hash, slot;
  28
  29         s_addr = addr & HPAGE_PMD_MASK;
  30         hpte_slot_array = get_hpte_slot_array(pmdp);
  31         /*
  32          * IF we try to do a HUGE PTE update after a withdraw is done.
  33          * we will find the below NULL. This happens when we do
  34          * split_huge_page_pmd
  35          */
  36         if (!hpte_slot_array)
  37                 return;
  38
  39         if (ppc_md.hugepage_invalidate)
  40                 return ppc_md.hugepage_invalidate(vsid, s_addr, hpte_slot_array,
  41                                                   psize, ssize);
  42         /*
  43          * No bluk hpte removal support, invalidate each entry
  44          */
  45         shift = mmu_psize_defs[psize].shift;
  46         max_hpte_count = HPAGE_PMD_SIZE >> shift;
  47         for (i = 0; i < max_hpte_count; i++) {
  48                 /*
  49                  * 8 bits per each hpte entries
  50                  * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
  51                  */
  52                 valid = hpte_valid(hpte_slot_array, i);
  53                 if (!valid)
  54                         continue;
  55                 hidx =  hpte_hash_index(hpte_slot_array, i);
  56
  57                 /* get the vpn */
  58                 addr = s_addr + (i * (1ul << shift));
  59                 vpn = hpt_vpn(addr, vsid, ssize);
  60                 hash = hpt_hash(vpn, shift, ssize);
  61                 if (hidx & _PTEIDX_SECONDARY)
  62                         hash = ~hash;
  63
  64                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
  65                 slot += hidx & _PTEIDX_GROUP_IX;
  66                 ppc_md.hpte_invalidate(slot, vpn, psize,
  67                                        MMU_PAGE_16M, ssize, 0);
  68         }
  69 }
  70
  71
  72 int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
  73                     pmd_t *pmdp, unsigned long trap, int local, int ssize,
  74                     unsigned int psize)
  75 {
  76         unsigned int index, valid;
  77         unsigned char *hpte_slot_array;
  78         unsigned long rflags, pa, hidx;
  79         unsigned long old_pmd, new_pmd;
  80         int ret, lpsize = MMU_PAGE_16M;
  81         unsigned long vpn, hash, shift, slot;
  82
  83         /*
  84          * atomically mark the linux large page PMD busy and dirty
  85          */
  86         do {
  87                 pmd_t pmd = ACCESS_ONCE(*pmdp);
  88
  89                 old_pmd = pmd_val(pmd);
  90                 /* If PMD busy, retry the access */
  91                 if (unlikely(old_pmd & _PAGE_BUSY))
  92                         return 0;
  93                 /* If PMD is trans splitting retry the access */
  94                 if (unlikely(old_pmd & _PAGE_SPLITTING))
  95                         return 0;
  96                 /* If PMD permissions don't match, take page fault */
  97                 if (unlikely(access & ~old_pmd))
  98                         return 1;
  99                 /*
 100                  * Try to lock the PTE, add ACCESSED and DIRTY if it was
 101                  * a write access
 102                  */
 103                 new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
 104                 if (access & _PAGE_RW)
 105                         new_pmd |= _PAGE_DIRTY;
 106         } while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
 107                                           old_pmd, new_pmd));
 108         /*
 109          * PP bits. _PAGE_USER is already PP bit 0x2, so we only
 110          * need to add in 0x1 if it's a read-only user page
 111          */
 112         rflags = new_pmd & _PAGE_USER;
 113         if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
 114                                            (new_pmd & _PAGE_DIRTY)))
 115                 rflags |= 0x1;
 116         /*
 117          * _PAGE_EXEC -> HW_NO_EXEC since it's inverted
 118          */
 119         rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
 120
 121 #if 0
 122         if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
 123
 124                 /*
 125                  * No CPU has hugepages but lacks no execute, so we
 126                  * don't need to worry about that case
 127                  */
 128                 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 129         }
 130 #endif
 131         /*
 132          * Find the slot index details for this ea, using base page size.
 133          */
 134         shift = mmu_psize_defs[psize].shift;
 135         index = (ea & ~HPAGE_PMD_MASK) >> shift;
 136         BUG_ON(index >= 4096);
 137
 138         vpn = hpt_vpn(ea, vsid, ssize);
 139         hash = hpt_hash(vpn, shift, ssize);
 140         hpte_slot_array = get_hpte_slot_array(pmdp);
 141         if (psize == MMU_PAGE_4K) {
 142                 /*
 143                  * invalidate the old hpte entry if we have that mapped via 64K
 144                  * base page size. This is because demote_segment won't flush
 145                  * hash page table entries.
 146                  */
 147                 if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO))
 148                         invalidate_old_hpte(vsid, ea, pmdp, MMU_PAGE_64K, ssize);
 149         }
 150
 151         valid = hpte_valid(hpte_slot_array, index);
 152         if (valid) {
 153                 /* update the hpte bits */
 154                 hidx =  hpte_hash_index(hpte_slot_array, index);
 155                 if (hidx & _PTEIDX_SECONDARY)
 156                         hash = ~hash;
 157                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 158                 slot += hidx & _PTEIDX_GROUP_IX;
 159
 160                 ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
 161                                            psize, lpsize, ssize, local);
 162                 /*
 163                  * We failed to update, try to insert a new entry.
 164                  */
 165                 if (ret == -1) {
 166                         /*
 167                          * large pte is marked busy, so we can be sure
 168                          * nobody is looking at hpte_slot_array. hence we can
 169                          * safely update this here.
 170                          */
 171                         valid = 0;
 172                         hpte_slot_array[index] = 0;
 173                 }
 174         }
 175
 176         if (!valid) {
 177                 unsigned long hpte_group;
 178
 179                 /* insert new entry */
 180                 pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
 181                 new_pmd |= _PAGE_HASHPTE;
 182
 183                 /* Add in WIMG bits */
 184                 rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
 185                                       _PAGE_GUARDED));
 186                 /*
 187                  * enable the memory coherence always
 188                  */
 189                 rflags |= HPTE_R_M;
 190 repeat:
 191                 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 192
 193                 /* Insert into the hash table, primary slot */
 194                 slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 195                                           psize, lpsize, ssize);
 196                 /*
 197                  * Primary is full, try the secondary
 198                  */
 199                 if (unlikely(slot == -1)) {
 200                         hpte_group = ((~hash & htab_hash_mask) *
 201                                       HPTES_PER_GROUP) & ~0x7UL;
 202                         slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
 203                                                   rflags, HPTE_V_SECONDARY,
 204                                                   psize, lpsize, ssize);
 205                         if (slot == -1) {
 206                                 if (mftb() & 0x1)
 207                                         hpte_group = ((hash & htab_hash_mask) *
 208                                                       HPTES_PER_GROUP) & ~0x7UL;
 209
 210                                 ppc_md.hpte_remove(hpte_group);
 211                                 goto repeat;
 212                         }
 213                 }
 214                 /*
 215                  * Hypervisor failure. Restore old pmd and return -1
 216                  * similar to __hash_page_*
 217                  */
 218                 if (unlikely(slot == -2)) {
 219                         *pmdp = __pmd(old_pmd);
 220                         hash_failure_debug(ea, access, vsid, trap, ssize,
 221                                            psize, lpsize, old_pmd);
 222                         return -1;
 223                 }
 224                 /*
 225                  * large pte is marked busy, so we can be sure
 226                  * nobody is looking at hpte_slot_array. hence we can
 227                  * safely update this here.
 228                  */
 229                 mark_hpte_slot_valid(hpte_slot_array, index, slot);
 230         }
 231         /*
 232          * Mark the pte with _PAGE_COMBO, if we are trying to hash it with
 233          * base page size 4k.
 234          */
 235         if (psize == MMU_PAGE_4K)
 236                 new_pmd |= _PAGE_COMBO;
 237         /*
 238          * The hpte valid is stored in the pgtable whose address is in the
 239          * second half of the PMD. Order this against clearing of the busy bit in
 240          * huge pmd.
 241          */
 242         smp_wmb();
 243         *pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
 244         return 0;
 245 }