LXR linux/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
  28static void pgd_ctor(void *addr)
  29{
  30        memset(addr, 0, PGD_TABLE_SIZE);
  31}
  32
  33static void pud_ctor(void *addr)
  34{
  35        memset(addr, 0, PUD_TABLE_SIZE);
  36}
  37
  38static void pmd_ctor(void *addr)
  39{
  40        memset(addr, 0, PMD_TABLE_SIZE);
  41}
  42
  43struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];
  44
  45/*
  46 * Create a kmem_cache() for pagetables.  This is not used for PTE
  47 * pages - they're linked to struct page, come from the normal free
  48 * pages pool and have a different entry size (see real_pte_t) to
  49 * everything else.  Caches created by this function are used for all
  50 * the higher level pagetables, and for hugepage pagetables.
  51 */
  52void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
  53{
  54        char *name;
  55        unsigned long table_size = sizeof(void *) << shift;
  56        unsigned long align = table_size;
  57
  58        /* When batching pgtable pointers for RCU freeing, we store
  59         * the index size in the low bits.  Table alignment must be
  60         * big enough to fit it.
  61         *
  62         * Likewise, hugeapge pagetable pointers contain a (different)
  63         * shift value in the low bits.  All tables must be aligned so
  64         * as to leave enough 0 bits in the address to contain it. */
  65        unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
  66                                     HUGEPD_SHIFT_MASK + 1);
  67        struct kmem_cache *new;
  68
  69        /* It would be nice if this was a BUILD_BUG_ON(), but at the
  70         * moment, gcc doesn't seem to recognize is_power_of_2 as a
  71         * constant expression, so so much for that. */
  72        BUG_ON(!is_power_of_2(minalign));
  73        BUG_ON((shift < 1) || (shift > MAX_PGTABLE_INDEX_SIZE));
  74
  75        if (PGT_CACHE(shift))
  76                return; /* Already have a cache of this size */
  77
  78        align = max_t(unsigned long, align, minalign);
  79        name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
  80        new = kmem_cache_create(name, table_size, align, 0, ctor);
  81        if (!new)
  82                panic("Could not allocate pgtable cache for order %d", shift);
  83
  84        kfree(name);
  85        pgtable_cache[shift - 1] = new;
  86
  87        pr_debug("Allocated pgtable cache for order %d\n", shift);
  88}
  89
  90
  91void pgtable_cache_init(void)
  92{
  93        pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
  94
  95        if (PMD_CACHE_INDEX && !PGT_CACHE(PMD_CACHE_INDEX))
  96                pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
  97        /*
  98         * In all current configs, when the PUD index exists it's the
  99         * same size as either the pgd or pmd index except with THP enabled
 100         * on book3s 64
 101         */
 102        if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
 103                pgtable_cache_add(PUD_INDEX_SIZE, pud_ctor);
 104}
 105