malloc/tst-mallocstate.c

   1 /* Emulate Emacs heap dumping to test malloc_set_state.
   2    Copyright (C) 2001-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stdbool.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <libc-symbols.h>
  24 #include <shlib-compat.h>
  25 #include <support/check.h>
  26 #include <support/support.h>
  27 #include <support/test-driver.h>
  28
  29 #include "malloc.h"
  30
  31 /* Make the compatibility symbols availabile to this test case.  */
  32 void *malloc_get_state (void);
  33 compat_symbol_reference (libc, malloc_get_state, malloc_get_state, GLIBC_2_0);
  34 int malloc_set_state (void *);
  35 compat_symbol_reference (libc, malloc_set_state, malloc_set_state, GLIBC_2_0);
  36
  37 /* Maximum object size in the fake heap.  */
  38 enum { max_size = 64 };
  39
  40 /* Allocation actions.  These are randomized actions executed on the
  41    dumped heap (see allocation_tasks below).  They are interspersed
  42    with operations on the new heap (see heap_activity).  */
  43 enum allocation_action
  44   {
  45     action_free,                /* Dumped and freed.  */
  46     action_realloc,             /* Dumped and realloc'ed.  */
  47     action_realloc_same,        /* Dumped and realloc'ed, same size.  */
  48     action_realloc_smaller,     /* Dumped and realloc'ed, shrunk.  */
  49     action_count
  50   };
  51
  52 /* Dumped heap.  Initialize it, so that the object is placed into the
  53    .data section, for increased realism.  The size is an upper bound;
  54    we use about half of the space.  */
  55 static size_t dumped_heap[action_count * max_size * max_size
  56                           / sizeof (size_t)] = {1};
  57
  58 /* Next free space in the dumped heap.  Also top of the heap at the
  59    end of the initialization procedure.  */
  60 static size_t *next_heap_chunk;
  61
  62 /* Copied from malloc.c and hooks.c.  The version is deliberately
  63    lower than the final version of malloc_set_state.  */
  64 # define NBINS 128
  65 # define MALLOC_STATE_MAGIC   0x444c4541l
  66 # define MALLOC_STATE_VERSION (0 * 0x100l + 4l)
  67 static struct
  68 {
  69   long magic;
  70   long version;
  71   void *av[NBINS * 2 + 2];
  72   char *sbrk_base;
  73   int sbrked_mem_bytes;
  74   unsigned long trim_threshold;
  75   unsigned long top_pad;
  76   unsigned int n_mmaps_max;
  77   unsigned long mmap_threshold;
  78   int check_action;
  79   unsigned long max_sbrked_mem;
  80   unsigned long max_total_mem;
  81   unsigned int n_mmaps;
  82   unsigned int max_n_mmaps;
  83   unsigned long mmapped_mem;
  84   unsigned long max_mmapped_mem;
  85   int using_malloc_checking;
  86   unsigned long max_fast;
  87   unsigned long arena_test;
  88   unsigned long arena_max;
  89   unsigned long narenas;
  90 } save_state =
  91   {
  92     .magic = MALLOC_STATE_MAGIC,
  93     .version = MALLOC_STATE_VERSION,
  94   };
  95
  96 /* Allocate a blob in the fake heap.  */
  97 static void *
  98 dumped_heap_alloc (size_t length)
  99 {
 100   /* malloc needs three state bits in the size field, so the minimum
 101      alignment is 8 even on 32-bit architectures.  malloc_set_state
 102      should be compatible with such heaps even if it currently
 103      provides more alignment to applications.  */
 104   enum
 105   {
 106     heap_alignment = 8,
 107     heap_alignment_mask = heap_alignment - 1
 108   };
 109   _Static_assert (sizeof (size_t) <= heap_alignment,
 110                   "size_t compatible with heap alignment");
 111
 112   /* Need at least this many bytes for metadata and application
 113      data. */
 114   size_t chunk_size = sizeof (size_t) + length;
 115   /* Round up the allocation size to the heap alignment.  */
 116   chunk_size += heap_alignment_mask;
 117   chunk_size &= ~heap_alignment_mask;
 118   TEST_VERIFY_EXIT ((chunk_size & 3) == 0);
 119   if (next_heap_chunk == NULL)
 120     /* Initialize the top of the heap.  Add one word of zero padding,
 121        to match existing practice.  */
 122     {
 123       dumped_heap[0] = 0;
 124       next_heap_chunk = dumped_heap + 1;
 125     }
 126   else
 127     /* The previous chunk is allocated. */
 128     chunk_size |= 1;
 129   *next_heap_chunk = chunk_size;
 130
 131   /* User data starts after the chunk header.  */
 132   void *result = next_heap_chunk + 1;
 133   next_heap_chunk += chunk_size / sizeof (size_t);
 134
 135   /* Mark the previous chunk as used.   */
 136   *next_heap_chunk = 1;
 137   return result;
 138 }
 139
 140 /* Global seed variable for the random number generator.  */
 141 static unsigned long long global_seed;
 142
 143 /* Simple random number generator.  The numbers are in the range from
 144    0 to UINT_MAX (inclusive).  */
 145 static unsigned int
 146 rand_next (unsigned long long *seed)
 147 {
 148   /* Linear congruential generated as used for MMIX.  */
 149   *seed = *seed * 6364136223846793005ULL + 1442695040888963407ULL;
 150   return *seed >> 32;
 151 }
 152
 153 /* Fill LENGTH bytes at BUFFER with random contents, as determined by
 154    SEED.  */
 155 static void
 156 randomize_buffer (unsigned char *buffer, size_t length,
 157                   unsigned long long seed)
 158 {
 159   for (size_t i = 0; i < length; ++i)
 160     buffer[i] = rand_next (&seed);
 161 }
 162
 163 /* Dumps the buffer to standard output,  in hexadecimal.  */
 164 static void
 165 dump_hex (unsigned char *buffer, size_t length)
 166 {
 167   for (int i = 0; i < length; ++i)
 168     printf (" %02X", buffer[i]);
 169 }
 170
 171 /* Set to true if an error is encountered.  */
 172 static bool errors = false;
 173
 174 /* Keep track of object allocations.  */
 175 struct allocation
 176 {
 177   unsigned char *data;
 178   unsigned int size;
 179   unsigned int seed;
 180 };
 181
 182 /* Check that the allocation task allocation has the expected
 183    contents.  */
 184 static void
 185 check_allocation (const struct allocation *alloc, int index)
 186 {
 187   size_t size = alloc->size;
 188   if (alloc->data == NULL)
 189     {
 190       printf ("error: NULL pointer for allocation of size %zu at %d, seed %u\n",
 191               size, index, alloc->seed);
 192       errors = true;
 193       return;
 194     }
 195
 196   unsigned char expected[4096];
 197   if (size > sizeof (expected))
 198     {
 199       printf ("error: invalid allocation size %zu at %d, seed %u\n",
 200               size, index, alloc->seed);
 201       errors = true;
 202       return;
 203     }
 204   randomize_buffer (expected, size, alloc->seed);
 205   if (memcmp (alloc->data, expected, size) != 0)
 206     {
 207       printf ("error: allocation %d data mismatch, size %zu, seed %u\n",
 208               index, size, alloc->seed);
 209       printf ("  expected:");
 210       dump_hex (expected, size);
 211       putc ('\n', stdout);
 212       printf ("    actual:");
 213       dump_hex (alloc->data, size);
 214       putc ('\n', stdout);
 215       errors = true;
 216     }
 217 }
 218
 219 /* A heap allocation combined with pending actions on it.  */
 220 struct allocation_task
 221 {
 222   struct allocation allocation;
 223   enum allocation_action action;
 224 };
 225
 226 /* Allocation tasks.  Initialized by init_allocation_tasks and used by
 227    perform_allocations.  */
 228 enum { allocation_task_count = action_count * max_size };
 229 static struct allocation_task allocation_tasks[allocation_task_count];
 230
 231 /* Fisher-Yates shuffle of allocation_tasks.  */
 232 static void
 233 shuffle_allocation_tasks (void)
 234 {
 235   for (int i = 0; i < allocation_task_count - 1; ++i)
 236     {
 237       /* Pick pair in the tail of the array.  */
 238       int j = i + (rand_next (&global_seed)
 239                    % ((unsigned) (allocation_task_count - i)));
 240       TEST_VERIFY_EXIT (j >= 0 && j < allocation_task_count);
 241       /* Exchange. */
 242       struct allocation_task tmp = allocation_tasks[i];
 243       allocation_tasks[i] = allocation_tasks[j];
 244       allocation_tasks[j] = tmp;
 245     }
 246 }
 247
 248 /* Set up the allocation tasks and the dumped heap.  */
 249 static void
 250 initial_allocations (void)
 251 {
 252   /* Initialize in a position-dependent way.  */
 253   for (int i = 0; i < allocation_task_count; ++i)
 254     allocation_tasks[i] = (struct allocation_task)
 255       {
 256         .allocation =
 257           {
 258             .size = 1 + (i / action_count),
 259             .seed = i,
 260           },
 261         .action = i % action_count
 262       };
 263
 264   /* Execute the tasks in a random order.  */
 265   shuffle_allocation_tasks ();
 266
 267   /* Initialize the contents of the dumped heap.   */
 268   for (int i = 0; i < allocation_task_count; ++i)
 269     {
 270       struct allocation_task *task = allocation_tasks + i;
 271       task->allocation.data = dumped_heap_alloc (task->allocation.size);
 272       randomize_buffer (task->allocation.data, task->allocation.size,
 273                         task->allocation.seed);
 274     }
 275
 276   for (int i = 0; i < allocation_task_count; ++i)
 277     check_allocation (&allocation_tasks[i].allocation, i);
 278 }
 279
 280 /* Indicates whether init_heap has run.  This variable needs to be
 281    volatile because malloc is declared __THROW, which implies it is a
 282    leaf function, but we expect it to run our hooks.  */
 283 static volatile bool heap_initialized;
 284
 285 /* Executed by glibc malloc, through __malloc_initialize_hook
 286    below.  */
 287 static void
 288 init_heap (void)
 289 {
 290   if (test_verbose)
 291     printf ("info: performing heap initialization\n");
 292   heap_initialized = true;
 293
 294   /* Populate the dumped heap.  */
 295   initial_allocations ();
 296
 297   /* Complete initialization of the saved heap data structure.  */
 298   save_state.sbrk_base = (void *) dumped_heap;
 299   save_state.sbrked_mem_bytes = sizeof (dumped_heap);
 300   /* Top pointer.  Adjust so that it points to the start of struct
 301      malloc_chunk.  */
 302   save_state.av[2] = (void *) (next_heap_chunk - 1);
 303
 304   /* Integrate the dumped heap into the process heap.  */
 305   TEST_VERIFY_EXIT (malloc_set_state (&save_state) == 0);
 306 }
 307
 308 /* Interpose the initialization callback.  */
 309 void (*volatile __malloc_initialize_hook) (void) = init_heap;
 310 compat_symbol_reference (libc, __malloc_initialize_hook,
 311                          __malloc_initialize_hook, GLIBC_2_0);
 312
 313 /* Simulate occasional unrelated heap activity in the non-dumped
 314    heap.  */
 315 enum { heap_activity_allocations_count = 32 };
 316 static struct allocation heap_activity_allocations
 317   [heap_activity_allocations_count] = {};
 318 static int heap_activity_seed_counter = 1000 * 1000;
 319
 320 static void
 321 heap_activity (void)
 322 {
 323   /* Only do this from time to time.  */
 324   if ((rand_next (&global_seed) % 4) == 0)
 325     {
 326       int slot = rand_next (&global_seed) % heap_activity_allocations_count;
 327       struct allocation *alloc = heap_activity_allocations + slot;
 328       if (alloc->data == NULL)
 329         {
 330           alloc->size = rand_next (&global_seed) % (4096U + 1);
 331           alloc->data = xmalloc (alloc->size);
 332           alloc->seed = heap_activity_seed_counter++;
 333           randomize_buffer (alloc->data, alloc->size, alloc->seed);
 334           check_allocation (alloc, 1000 + slot);
 335         }
 336       else
 337         {
 338           check_allocation (alloc, 1000 + slot);
 339           free (alloc->data);
 340           alloc->data = NULL;
 341         }
 342     }
 343 }
 344
 345 static void
 346 heap_activity_deallocate (void)
 347 {
 348   for (int i = 0; i < heap_activity_allocations_count; ++i)
 349     free (heap_activity_allocations[i].data);
 350 }
 351
 352 /* Perform a full heap check across the dumped heap allocation tasks,
 353    and the simulated heap activity directly above.  */
 354 static void
 355 full_heap_check (void)
 356 {
 357   /* Dumped heap.  */
 358   for (int i = 0; i < allocation_task_count; ++i)
 359     if (allocation_tasks[i].allocation.data != NULL)
 360       check_allocation (&allocation_tasks[i].allocation, i);
 361
 362   /* Heap activity allocations.  */
 363   for (int i = 0; i < heap_activity_allocations_count; ++i)
 364     if (heap_activity_allocations[i].data != NULL)
 365       check_allocation (heap_activity_allocations + i, i);
 366 }
 367
 368 /* Used as an optimization barrier to force a heap allocation.  */
 369 __attribute__ ((noinline, noclone))
 370 static void
 371 my_free (void *ptr)
 372 {
 373   free (ptr);
 374 }
 375
 376 static int
 377 do_test (void)
 378 {
 379   my_free (malloc (1));
 380   TEST_VERIFY_EXIT (heap_initialized);
 381
 382   /* The first pass performs the randomly generated allocation
 383      tasks.  */
 384   if (test_verbose)
 385     printf ("info: first pass through allocation tasks\n");
 386   full_heap_check ();
 387
 388   /* Execute the post-undump tasks in a random order.  */
 389   shuffle_allocation_tasks ();
 390
 391   for (int i = 0; i < allocation_task_count; ++i)
 392     {
 393       heap_activity ();
 394       struct allocation_task *task = allocation_tasks + i;
 395       switch (task->action)
 396         {
 397         case action_free:
 398           check_allocation (&task->allocation, i);
 399           free (task->allocation.data);
 400           task->allocation.data = NULL;
 401           break;
 402
 403         case action_realloc:
 404           check_allocation (&task->allocation, i);
 405           task->allocation.data = xrealloc
 406             (task->allocation.data, task->allocation.size + max_size);
 407           check_allocation (&task->allocation, i);
 408           break;
 409
 410         case action_realloc_same:
 411           check_allocation (&task->allocation, i);
 412           task->allocation.data = xrealloc
 413             (task->allocation.data, task->allocation.size);
 414           check_allocation (&task->allocation, i);
 415           break;
 416
 417         case action_realloc_smaller:
 418           check_allocation (&task->allocation, i);
 419           size_t new_size = task->allocation.size - 1;
 420           task->allocation.data = xrealloc (task->allocation.data, new_size);
 421           if (new_size == 0)
 422             {
 423               if (task->allocation.data != NULL)
 424                 {
 425                   printf ("error: realloc with size zero did not deallocate\n");
 426                   errors = true;
 427                 }
 428               /* No further action on this task.  */
 429               task->action = action_free;
 430             }
 431           else
 432             {
 433               task->allocation.size = new_size;
 434               check_allocation (&task->allocation, i);
 435             }
 436           break;
 437
 438         case action_count:
 439           FAIL_EXIT1 ("task->action should never be action_count");
 440         }
 441       full_heap_check ();
 442     }
 443
 444   /* The second pass frees the objects which were allocated during the
 445      first pass.  */
 446   if (test_verbose)
 447     printf ("info: second pass through allocation tasks\n");
 448
 449   shuffle_allocation_tasks ();
 450   for (int i = 0; i < allocation_task_count; ++i)
 451     {
 452       heap_activity ();
 453       struct allocation_task *task = allocation_tasks + i;
 454       switch (task->action)
 455         {
 456         case action_free:
 457           /* Already freed, nothing to do.  */
 458           break;
 459
 460         case action_realloc:
 461         case action_realloc_same:
 462         case action_realloc_smaller:
 463           check_allocation (&task->allocation, i);
 464           free (task->allocation.data);
 465           task->allocation.data = NULL;
 466           break;
 467
 468         case action_count:
 469           FAIL_EXIT1 ("task->action should never be action_count");
 470         }
 471       full_heap_check ();
 472     }
 473
 474   heap_activity_deallocate ();
 475
 476   /* Check that the malloc_get_state stub behaves in the intended
 477      way.  */
 478   errno = 0;
 479   if (malloc_get_state () != NULL)
 480     {
 481       printf ("error: malloc_get_state succeeded\n");
 482       errors = true;
 483     }
 484   if (errno != ENOSYS)
 485     {
 486       printf ("error: malloc_get_state: %m\n");
 487       errors = true;
 488     }
 489
 490   return errors;
 491 }
 492
 493 #include <support/test-driver.c>