arch/x86/mm/pageattr-test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * self test for change_page_attr.
   4  *
   5  * Clears the a test pte bit on random pages in the direct mapping,
   6  * then reverts and compares page tables forwards and afterwards.
   7  */
   8 #include <linux/memblock.h>
   9 #include <linux/kthread.h>
  10 #include <linux/random.h>
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/mm.h>
  14 #include <linux/vmalloc.h>
  15
  16 #include <asm/cacheflush.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/kdebug.h>
  19
  20 /*
  21  * Only print the results of the first pass:
  22  */
  23 static __read_mostly int print = 1;
  24
  25 enum {
  26         NTEST                   = 400,
  27 #ifdef CONFIG_X86_64
  28         LPS                     = (1 << PMD_SHIFT),
  29 #elif defined(CONFIG_X86_PAE)
  30         LPS                     = (1 << PMD_SHIFT),
  31 #else
  32         LPS                     = (1 << 22),
  33 #endif
  34         GPS                     = (1<<30)
  35 };
  36
  37 #define PAGE_CPA_TEST   __pgprot(_PAGE_CPA_TEST)
  38
  39 static int pte_testbit(pte_t pte)
  40 {
  41         return pte_flags(pte) & _PAGE_SOFTW1;
  42 }
  43
  44 struct split_state {
  45         long lpg, gpg, spg, exec;
  46         long min_exec, max_exec;
  47 };
  48
  49 static int print_split(struct split_state *s)
  50 {
  51         long i, expected, missed = 0;
  52         int err = 0;
  53
  54         s->lpg = s->gpg = s->spg = s->exec = 0;
  55         s->min_exec = ~0UL;
  56         s->max_exec = 0;
  57         for (i = 0; i < max_pfn_mapped; ) {
  58                 unsigned long addr = (unsigned long)__va(i << PAGE_SHIFT);
  59                 unsigned int level;
  60                 pte_t *pte;
  61
  62                 pte = lookup_address(addr, &level);
  63                 if (!pte) {
  64                         missed++;
  65                         i++;
  66                         continue;
  67                 }
  68
  69                 if (level == PG_LEVEL_1G && sizeof(long) == 8) {
  70                         s->gpg++;
  71                         i += GPS/PAGE_SIZE;
  72                 } else if (level == PG_LEVEL_2M) {
  73                         if ((pte_val(*pte) & _PAGE_PRESENT) && !(pte_val(*pte) & _PAGE_PSE)) {
  74                                 printk(KERN_ERR
  75                                         "%lx level %d but not PSE %Lx\n",
  76                                         addr, level, (u64)pte_val(*pte));
  77                                 err = 1;
  78                         }
  79                         s->lpg++;
  80                         i += LPS/PAGE_SIZE;
  81                 } else {
  82                         s->spg++;
  83                         i++;
  84                 }
  85                 if (!(pte_val(*pte) & _PAGE_NX)) {
  86                         s->exec++;
  87                         if (addr < s->min_exec)
  88                                 s->min_exec = addr;
  89                         if (addr > s->max_exec)
  90                                 s->max_exec = addr;
  91                 }
  92         }
  93         if (print) {
  94                 printk(KERN_INFO
  95                         " 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n",
  96                         s->spg, s->lpg, s->gpg, s->exec,
  97                         s->min_exec != ~0UL ? s->min_exec : 0,
  98                         s->max_exec, missed);
  99         }
 100
 101         expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed;
 102         if (expected != i) {
 103                 printk(KERN_ERR "CPA max_pfn_mapped %lu but expected %lu\n",
 104                         max_pfn_mapped, expected);
 105                 return 1;
 106         }
 107         return err;
 108 }
 109
 110 static unsigned long addr[NTEST];
 111 static unsigned int len[NTEST];
 112
 113 /* Change the global bit on random pages in the direct mapping */
 114 static int pageattr_test(void)
 115 {
 116         struct split_state sa, sb, sc;
 117         unsigned long *bm;
 118         pte_t *pte, pte0;
 119         int failed = 0;
 120         unsigned int level;
 121         int i, k;
 122         int err;
 123         unsigned long test_addr;
 124
 125         if (print)
 126                 printk(KERN_INFO "CPA self-test:\n");
 127
 128         bm = vzalloc((max_pfn_mapped + 7) / 8);
 129         if (!bm) {
 130                 printk(KERN_ERR "CPA Cannot vmalloc bitmap\n");
 131                 return -ENOMEM;
 132         }
 133
 134         failed += print_split(&sa);
 135
 136         for (i = 0; i < NTEST; i++) {
 137                 unsigned long pfn = prandom_u32() % max_pfn_mapped;
 138
 139                 addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
 140                 len[i] = prandom_u32() % 100;
 141                 len[i] = min_t(unsigned long, len[i], max_pfn_mapped - pfn - 1);
 142
 143                 if (len[i] == 0)
 144                         len[i] = 1;
 145
 146                 pte = NULL;
 147                 pte0 = pfn_pte(0, __pgprot(0)); /* shut gcc up */
 148
 149                 for (k = 0; k < len[i]; k++) {
 150                         pte = lookup_address(addr[i] + k*PAGE_SIZE, &level);
 151                         if (!pte || pgprot_val(pte_pgprot(*pte)) == 0 ||
 152                             !(pte_val(*pte) & _PAGE_PRESENT)) {
 153                                 addr[i] = 0;
 154                                 break;
 155                         }
 156                         if (k == 0) {
 157                                 pte0 = *pte;
 158                         } else {
 159                                 if (pgprot_val(pte_pgprot(*pte)) !=
 160                                         pgprot_val(pte_pgprot(pte0))) {
 161                                         len[i] = k;
 162                                         break;
 163                                 }
 164                         }
 165                         if (test_bit(pfn + k, bm)) {
 166                                 len[i] = k;
 167                                 break;
 168                         }
 169                         __set_bit(pfn + k, bm);
 170                 }
 171                 if (!addr[i] || !pte || !k) {
 172                         addr[i] = 0;
 173                         continue;
 174                 }
 175
 176                 test_addr = addr[i];
 177                 err = change_page_attr_set(&test_addr, len[i], PAGE_CPA_TEST, 0);
 178                 if (err < 0) {
 179                         printk(KERN_ERR "CPA %d failed %d\n", i, err);
 180                         failed++;
 181                 }
 182
 183                 pte = lookup_address(addr[i], &level);
 184                 if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) {
 185                         printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i],
 186                                 pte ? (u64)pte_val(*pte) : 0ULL);
 187                         failed++;
 188                 }
 189                 if (level != PG_LEVEL_4K) {
 190                         printk(KERN_ERR "CPA %lx: unexpected level %d\n",
 191                                 addr[i], level);
 192                         failed++;
 193                 }
 194
 195         }
 196         vfree(bm);
 197
 198         failed += print_split(&sb);
 199
 200         for (i = 0; i < NTEST; i++) {
 201                 if (!addr[i])
 202                         continue;
 203                 pte = lookup_address(addr[i], &level);
 204                 if (!pte) {
 205                         printk(KERN_ERR "CPA lookup of %lx failed\n", addr[i]);
 206                         failed++;
 207                         continue;
 208                 }
 209                 test_addr = addr[i];
 210                 err = change_page_attr_clear(&test_addr, len[i], PAGE_CPA_TEST, 0);
 211                 if (err < 0) {
 212                         printk(KERN_ERR "CPA reverting failed: %d\n", err);
 213                         failed++;
 214                 }
 215                 pte = lookup_address(addr[i], &level);
 216                 if (!pte || pte_testbit(*pte)) {
 217                         printk(KERN_ERR "CPA %lx: bad pte after revert %Lx\n",
 218                                 addr[i], pte ? (u64)pte_val(*pte) : 0ULL);
 219                         failed++;
 220                 }
 221
 222         }
 223
 224         failed += print_split(&sc);
 225
 226         if (failed) {
 227                 WARN(1, KERN_ERR "NOT PASSED. Please report.\n");
 228                 return -EINVAL;
 229         } else {
 230                 if (print)
 231                         printk(KERN_INFO "ok.\n");
 232         }
 233
 234         return 0;
 235 }
 236
 237 static int do_pageattr_test(void *__unused)
 238 {
 239         while (!kthread_should_stop()) {
 240                 schedule_timeout_interruptible(HZ*30);
 241                 if (pageattr_test() < 0)
 242                         break;
 243                 if (print)
 244                         print--;
 245         }
 246         return 0;
 247 }
 248
 249 static int start_pageattr_test(void)
 250 {
 251         struct task_struct *p;
 252
 253         p = kthread_create(do_pageattr_test, NULL, "pageattr-test");
 254         if (!IS_ERR(p))
 255                 wake_up_process(p);
 256         else
 257                 WARN_ON(1);
 258
 259         return 0;
 260 }
 261 device_initcall(start_pageattr_test);