arch/powerpc/mm/init-common.c

   1 /*
   2  *  PowerPC version
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   6  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   7  *    Copyright (C) 1996 Paul Mackerras
   8  *
   9  *  Derived from "arch/i386/mm/init.c"
  10  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  11  *
  12  *  Dave Engebretsen <engebret@us.ibm.com>
  13  *      Rework for PPC64 port.
  14  *
  15  *  This program is free software; you can redistribute it and/or
  16  *  modify it under the terms of the GNU General Public License
  17  *  as published by the Free Software Foundation; either version
  18  *  2 of the License, or (at your option) any later version.
  19  *
  20  */
  21
  22 #undef DEBUG
  23
  24 #include <linux/string.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/pgtable.h>
  27
  28 static void pgd_ctor(void *addr)
  29 {
  30         memset(addr, 0, PGD_TABLE_SIZE);
  31 }
  32
  33 static void pud_ctor(void *addr)
  34 {
  35         memset(addr, 0, PUD_TABLE_SIZE);
  36 }
  37
  38 static void pmd_ctor(void *addr)
  39 {
  40         memset(addr, 0, PMD_TABLE_SIZE);
  41 }
  42
  43 struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];
  44 EXPORT_SYMBOL_GPL(pgtable_cache);       /* used by kvm_hv module */
  45
  46 /*
  47  * Create a kmem_cache() for pagetables.  This is not used for PTE
  48  * pages - they're linked to struct page, come from the normal free
  49  * pages pool and have a different entry size (see real_pte_t) to
  50  * everything else.  Caches created by this function are used for all
  51  * the higher level pagetables, and for hugepage pagetables.
  52  */
  53 void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
  54 {
  55         char *name;
  56         unsigned long table_size = sizeof(void *) << shift;
  57         unsigned long align = table_size;
  58
  59         /* When batching pgtable pointers for RCU freeing, we store
  60          * the index size in the low bits.  Table alignment must be
  61          * big enough to fit it.
  62          *
  63          * Likewise, hugeapge pagetable pointers contain a (different)
  64          * shift value in the low bits.  All tables must be aligned so
  65          * as to leave enough 0 bits in the address to contain it. */
  66         unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
  67                                      HUGEPD_SHIFT_MASK + 1);
  68         struct kmem_cache *new;
  69
  70         /* It would be nice if this was a BUILD_BUG_ON(), but at the
  71          * moment, gcc doesn't seem to recognize is_power_of_2 as a
  72          * constant expression, so so much for that. */
  73         BUG_ON(!is_power_of_2(minalign));
  74         BUG_ON((shift < 1) || (shift > MAX_PGTABLE_INDEX_SIZE));
  75
  76         if (PGT_CACHE(shift))
  77                 return; /* Already have a cache of this size */
  78
  79         align = max_t(unsigned long, align, minalign);
  80         name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
  81         new = kmem_cache_create(name, table_size, align, 0, ctor);
  82         if (!new)
  83                 panic("Could not allocate pgtable cache for order %d", shift);
  84
  85         kfree(name);
  86         pgtable_cache[shift - 1] = new;
  87
  88         pr_debug("Allocated pgtable cache for order %d\n", shift);
  89 }
  90 EXPORT_SYMBOL_GPL(pgtable_cache_add);   /* used by kvm_hv module */
  91
  92 void pgtable_cache_init(void)
  93 {
  94         pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
  95
  96         if (PMD_CACHE_INDEX && !PGT_CACHE(PMD_CACHE_INDEX))
  97                 pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
  98         /*
  99          * In all current configs, when the PUD index exists it's the
 100          * same size as either the pgd or pmd index except with THP enabled
 101          * on book3s 64
 102          */
 103         if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
 104                 pgtable_cache_add(PUD_INDEX_SIZE, pud_ctor);
 105 }