arch/x86/mm/pageattr-test.c

   1 /*
   2  * self test for change_page_attr.
   3  *
   4  * Clears the a test pte bit on random pages in the direct mapping,
   5  * then reverts and compares page tables forwards and afterwards.
   6  */
   7 #include <linux/bootmem.h>
   8 #include <linux/kthread.h>
   9 #include <linux/random.h>
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/mm.h>
  13
  14 #include <asm/cacheflush.h>
  15 #include <asm/pgtable.h>
  16 #include <asm/kdebug.h>
  17
  18 /*
  19  * Only print the results of the first pass:
  20  */
  21 static __read_mostly int print = 1;
  22
  23 enum {
  24         NTEST                   = 400,
  25 #ifdef CONFIG_X86_64
  26         LPS                     = (1 << PMD_SHIFT),
  27 #elif defined(CONFIG_X86_PAE)
  28         LPS                     = (1 << PMD_SHIFT),
  29 #else
  30         LPS                     = (1 << 22),
  31 #endif
  32         GPS                     = (1<<30)
  33 };
  34
  35 #define PAGE_TESTBIT    __pgprot(_PAGE_UNUSED1)
  36
  37 static int pte_testbit(pte_t pte)
  38 {
  39         return pte_flags(pte) & _PAGE_UNUSED1;
  40 }
  41
  42 struct split_state {
  43         long lpg, gpg, spg, exec;
  44         long min_exec, max_exec;
  45 };
  46
  47 static int print_split(struct split_state *s)
  48 {
  49         long i, expected, missed = 0;
  50         int err = 0;
  51
  52         s->lpg = s->gpg = s->spg = s->exec = 0;
  53         s->min_exec = ~0UL;
  54         s->max_exec = 0;
  55         for (i = 0; i < max_pfn_mapped; ) {
  56                 unsigned long addr = (unsigned long)__va(i << PAGE_SHIFT);
  57                 unsigned int level;
  58                 pte_t *pte;
  59
  60                 pte = lookup_address(addr, &level);
  61                 if (!pte) {
  62                         missed++;
  63                         i++;
  64                         continue;
  65                 }
  66
  67                 if (level == PG_LEVEL_1G && sizeof(long) == 8) {
  68                         s->gpg++;
  69                         i += GPS/PAGE_SIZE;
  70                 } else if (level == PG_LEVEL_2M) {
  71                         if (!(pte_val(*pte) & _PAGE_PSE)) {
  72                                 printk(KERN_ERR
  73                                         "%lx level %d but not PSE %Lx\n",
  74                                         addr, level, (u64)pte_val(*pte));
  75                                 err = 1;
  76                         }
  77                         s->lpg++;
  78                         i += LPS/PAGE_SIZE;
  79                 } else {
  80                         s->spg++;
  81                         i++;
  82                 }
  83                 if (!(pte_val(*pte) & _PAGE_NX)) {
  84                         s->exec++;
  85                         if (addr < s->min_exec)
  86                                 s->min_exec = addr;
  87                         if (addr > s->max_exec)
  88                                 s->max_exec = addr;
  89                 }
  90         }
  91         if (print) {
  92                 printk(KERN_INFO
  93                         " 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n",
  94                         s->spg, s->lpg, s->gpg, s->exec,
  95                         s->min_exec != ~0UL ? s->min_exec : 0,
  96                         s->max_exec, missed);
  97         }
  98
  99         expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed;
 100         if (expected != i) {
 101                 printk(KERN_ERR "CPA max_pfn_mapped %lu but expected %lu\n",
 102                         max_pfn_mapped, expected);
 103                 return 1;
 104         }
 105         return err;
 106 }
 107
 108 static unsigned long addr[NTEST];
 109 static unsigned int len[NTEST];
 110
 111 /* Change the global bit on random pages in the direct mapping */
 112 static int pageattr_test(void)
 113 {
 114         struct split_state sa, sb, sc;
 115         unsigned long *bm;
 116         pte_t *pte, pte0;
 117         int failed = 0;
 118         unsigned int level;
 119         int i, k;
 120         int err;
 121
 122         if (print)
 123                 printk(KERN_INFO "CPA self-test:\n");
 124
 125         bm = vmalloc((max_pfn_mapped + 7) / 8);
 126         if (!bm) {
 127                 printk(KERN_ERR "CPA Cannot vmalloc bitmap\n");
 128                 return -ENOMEM;
 129         }
 130         memset(bm, 0, (max_pfn_mapped + 7) / 8);
 131
 132         failed += print_split(&sa);
 133         srandom32(100);
 134
 135         for (i = 0; i < NTEST; i++) {
 136                 unsigned long pfn = random32() % max_pfn_mapped;
 137
 138                 addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
 139                 len[i] = random32() % 100;
 140                 len[i] = min_t(unsigned long, len[i], max_pfn_mapped - pfn - 1);
 141
 142                 if (len[i] == 0)
 143                         len[i] = 1;
 144
 145                 pte = NULL;
 146                 pte0 = pfn_pte(0, __pgprot(0)); /* shut gcc up */
 147
 148                 for (k = 0; k < len[i]; k++) {
 149                         pte = lookup_address(addr[i] + k*PAGE_SIZE, &level);
 150                         if (!pte || pgprot_val(pte_pgprot(*pte)) == 0 ||
 151                             !(pte_val(*pte) & _PAGE_PRESENT)) {
 152                                 addr[i] = 0;
 153                                 break;
 154                         }
 155                         if (k == 0) {
 156                                 pte0 = *pte;
 157                         } else {
 158                                 if (pgprot_val(pte_pgprot(*pte)) !=
 159                                         pgprot_val(pte_pgprot(pte0))) {
 160                                         len[i] = k;
 161                                         break;
 162                                 }
 163                         }
 164                         if (test_bit(pfn + k, bm)) {
 165                                 len[i] = k;
 166                                 break;
 167                         }
 168                         __set_bit(pfn + k, bm);
 169                 }
 170                 if (!addr[i] || !pte || !k) {
 171                         addr[i] = 0;
 172                         continue;
 173                 }
 174
 175                 err = change_page_attr_set(addr[i], len[i], PAGE_TESTBIT);
 176                 if (err < 0) {
 177                         printk(KERN_ERR "CPA %d failed %d\n", i, err);
 178                         failed++;
 179                 }
 180
 181                 pte = lookup_address(addr[i], &level);
 182                 if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) {
 183                         printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i],
 184                                 pte ? (u64)pte_val(*pte) : 0ULL);
 185                         failed++;
 186                 }
 187                 if (level != PG_LEVEL_4K) {
 188                         printk(KERN_ERR "CPA %lx: unexpected level %d\n",
 189                                 addr[i], level);
 190                         failed++;
 191                 }
 192
 193         }
 194         vfree(bm);
 195
 196         failed += print_split(&sb);
 197
 198         for (i = 0; i < NTEST; i++) {
 199                 if (!addr[i])
 200                         continue;
 201                 pte = lookup_address(addr[i], &level);
 202                 if (!pte) {
 203                         printk(KERN_ERR "CPA lookup of %lx failed\n", addr[i]);
 204                         failed++;
 205                         continue;
 206                 }
 207                 err = change_page_attr_clear(addr[i], len[i], PAGE_TESTBIT);
 208                 if (err < 0) {
 209                         printk(KERN_ERR "CPA reverting failed: %d\n", err);
 210                         failed++;
 211                 }
 212                 pte = lookup_address(addr[i], &level);
 213                 if (!pte || pte_testbit(*pte)) {
 214                         printk(KERN_ERR "CPA %lx: bad pte after revert %Lx\n",
 215                                 addr[i], pte ? (u64)pte_val(*pte) : 0ULL);
 216                         failed++;
 217                 }
 218
 219         }
 220
 221         failed += print_split(&sc);
 222
 223         if (failed) {
 224                 WARN(1, KERN_ERR "NOT PASSED. Please report.\n");
 225                 return -EINVAL;
 226         } else {
 227                 if (print)
 228                         printk(KERN_INFO "ok.\n");
 229         }
 230
 231         return 0;
 232 }
 233
 234 static int do_pageattr_test(void *__unused)
 235 {
 236         while (!kthread_should_stop()) {
 237                 schedule_timeout_interruptible(HZ*30);
 238                 if (pageattr_test() < 0)
 239                         break;
 240                 if (print)
 241                         print--;
 242         }
 243         return 0;
 244 }
 245
 246 static int start_pageattr_test(void)
 247 {
 248         struct task_struct *p;
 249
 250         p = kthread_create(do_pageattr_test, NULL, "pageattr-test");
 251         if (!IS_ERR(p))
 252                 wake_up_process(p);
 253         else
 254                 WARN_ON(1);
 255
 256         return 0;
 257 }
 258
 259 module_init(start_pageattr_test);