root/arch/powerpc/mm/init-common.c

DEFINITIONS

1. parse_nosmep
2. parse_nosmap
3. setup_kup
4. ctor
5. pgtable_cache_add
6. pgtable_cache_init

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  PowerPC version
   4  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   5  *
   6  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   7  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   8  *    Copyright (C) 1996 Paul Mackerras
   9  *
  10  *  Derived from "arch/i386/mm/init.c"
  11  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  12  *
  13  *  Dave Engebretsen <engebret@us.ibm.com>
  14  *      Rework for PPC64 port.
  15  */
  16 
  17 #undef DEBUG
  18 
  19 #include <linux/string.h>
  20 #include <asm/pgalloc.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/kup.h>
  23 
  24 static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
  25 static bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
  26 
  27 static int __init parse_nosmep(char *p)
  28 {
  29         disable_kuep = true;
  30         pr_warn("Disabling Kernel Userspace Execution Prevention\n");
  31         return 0;
  32 }
  33 early_param("nosmep", parse_nosmep);
  34 
  35 static int __init parse_nosmap(char *p)
  36 {
  37         disable_kuap = true;
  38         pr_warn("Disabling Kernel Userspace Access Protection\n");
  39         return 0;
  40 }
  41 early_param("nosmap", parse_nosmap);
  42 
  43 void __ref setup_kup(void)
  44 {
  45         setup_kuep(disable_kuep);
  46         setup_kuap(disable_kuap);
  47 }
  48 
  49 #define CTOR(shift) static void ctor_##shift(void *addr) \
  50 {                                                       \
  51         memset(addr, 0, sizeof(void *) << (shift));     \
  52 }
  53 
  54 CTOR(0); CTOR(1); CTOR(2); CTOR(3); CTOR(4); CTOR(5); CTOR(6); CTOR(7);
  55 CTOR(8); CTOR(9); CTOR(10); CTOR(11); CTOR(12); CTOR(13); CTOR(14); CTOR(15);
  56 
  57 static inline void (*ctor(int shift))(void *)
  58 {
  59         BUILD_BUG_ON(MAX_PGTABLE_INDEX_SIZE != 15);
  60 
  61         switch (shift) {
  62         case 0: return ctor_0;
  63         case 1: return ctor_1;
  64         case 2: return ctor_2;
  65         case 3: return ctor_3;
  66         case 4: return ctor_4;
  67         case 5: return ctor_5;
  68         case 6: return ctor_6;
  69         case 7: return ctor_7;
  70         case 8: return ctor_8;
  71         case 9: return ctor_9;
  72         case 10: return ctor_10;
  73         case 11: return ctor_11;
  74         case 12: return ctor_12;
  75         case 13: return ctor_13;
  76         case 14: return ctor_14;
  77         case 15: return ctor_15;
  78         }
  79         return NULL;
  80 }
  81 
  82 struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE + 1];
  83 EXPORT_SYMBOL_GPL(pgtable_cache);       /* used by kvm_hv module */
  84 
  85 /*
  86  * Create a kmem_cache() for pagetables.  This is not used for PTE
  87  * pages - they're linked to struct page, come from the normal free
  88  * pages pool and have a different entry size (see real_pte_t) to
  89  * everything else.  Caches created by this function are used for all
  90  * the higher level pagetables, and for hugepage pagetables.
  91  */
  92 void pgtable_cache_add(unsigned int shift)
  93 {
  94         char *name;
  95         unsigned long table_size = sizeof(void *) << shift;
  96         unsigned long align = table_size;
  97 
  98         /* When batching pgtable pointers for RCU freeing, we store
  99          * the index size in the low bits.  Table alignment must be
 100          * big enough to fit it.
 101          *
 102          * Likewise, hugeapge pagetable pointers contain a (different)
 103          * shift value in the low bits.  All tables must be aligned so
 104          * as to leave enough 0 bits in the address to contain it. */
 105         unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
 106                                      HUGEPD_SHIFT_MASK + 1);
 107         struct kmem_cache *new;
 108 
 109         /* It would be nice if this was a BUILD_BUG_ON(), but at the
 110          * moment, gcc doesn't seem to recognize is_power_of_2 as a
 111          * constant expression, so so much for that. */
 112         BUG_ON(!is_power_of_2(minalign));
 113         BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
 114 
 115         if (PGT_CACHE(shift))
 116                 return; /* Already have a cache of this size */
 117 
 118         align = max_t(unsigned long, align, minalign);
 119         name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
 120         new = kmem_cache_create(name, table_size, align, 0, ctor(shift));
 121         if (!new)
 122                 panic("Could not allocate pgtable cache for order %d", shift);
 123 
 124         kfree(name);
 125         pgtable_cache[shift] = new;
 126 
 127         pr_debug("Allocated pgtable cache for order %d\n", shift);
 128 }
 129 EXPORT_SYMBOL_GPL(pgtable_cache_add);   /* used by kvm_hv module */
 130 
 131 void pgtable_cache_init(void)
 132 {
 133         pgtable_cache_add(PGD_INDEX_SIZE);
 134 
 135         if (PMD_CACHE_INDEX)
 136                 pgtable_cache_add(PMD_CACHE_INDEX);
 137         /*
 138          * In all current configs, when the PUD index exists it's the
 139          * same size as either the pgd or pmd index except with THP enabled
 140          * on book3s 64
 141          */
 142         if (PUD_CACHE_INDEX)
 143                 pgtable_cache_add(PUD_CACHE_INDEX);
 144 }