kernel/kallsyms_selftest.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Test the function and performance of kallsyms
   4  *
   5  * Copyright (C) Huawei Technologies Co., Ltd., 2022
   6  *
   7  * Authors: Zhen Lei <thunder.leizhen@huawei.com> Huawei
   8  */
   9
  10 #define pr_fmt(fmt) "kallsyms_selftest: " fmt
  11
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/kallsyms.h>
  15 #include <linux/random.h>
  16 #include <linux/sched/clock.h>
  17 #include <linux/kthread.h>
  18 #include <linux/vmalloc.h>
  19
  20 #include "kallsyms_internal.h"
  21 #include "kallsyms_selftest.h"
  22
  23
  24 #define MAX_NUM_OF_RECORDS              64
  25
  26 struct test_stat {
  27         int min;
  28         int max;
  29         int save_cnt;
  30         int real_cnt;
  31         int perf;
  32         u64 sum;
  33         char *name;
  34         unsigned long addr;
  35         unsigned long addrs[MAX_NUM_OF_RECORDS];
  36 };
  37
  38 struct test_item {
  39         char *name;
  40         unsigned long addr;
  41 };
  42
  43 #define ITEM_FUNC(s)                            \
  44         {                                       \
  45                 .name = #s,                     \
  46                 .addr = (unsigned long)s,       \
  47         }
  48
  49 #define ITEM_DATA(s)                            \
  50         {                                       \
  51                 .name = #s,                     \
  52                 .addr = (unsigned long)&s,      \
  53         }
  54
  55
  56 static int kallsyms_test_var_bss_static;
  57 static int kallsyms_test_var_data_static = 1;
  58 int kallsyms_test_var_bss;
  59 int kallsyms_test_var_data = 1;
  60
  61 static int kallsyms_test_func_static(void)
  62 {
  63         kallsyms_test_var_bss_static++;
  64         kallsyms_test_var_data_static++;
  65
  66         return 0;
  67 }
  68
  69 int kallsyms_test_func(void)
  70 {
  71         return kallsyms_test_func_static();
  72 }
  73
  74 __weak int kallsyms_test_func_weak(void)
  75 {
  76         kallsyms_test_var_bss++;
  77         kallsyms_test_var_data++;
  78         return 0;
  79 }
  80
  81 static struct test_item test_items[] = {
  82         ITEM_FUNC(kallsyms_test_func_static),
  83         ITEM_FUNC(kallsyms_test_func),
  84         ITEM_FUNC(kallsyms_test_func_weak),
  85         ITEM_FUNC(vmalloc),
  86         ITEM_FUNC(vfree),
  87 #ifdef CONFIG_KALLSYMS_ALL
  88         ITEM_DATA(kallsyms_test_var_bss_static),
  89         ITEM_DATA(kallsyms_test_var_data_static),
  90         ITEM_DATA(kallsyms_test_var_bss),
  91         ITEM_DATA(kallsyms_test_var_data),
  92         ITEM_DATA(vmap_area_list),
  93 #endif
  94 };
  95
  96 static char stub_name[KSYM_NAME_LEN];
  97
  98 static int stat_symbol_len(void *data, const char *name, struct module *mod, unsigned long addr)
  99 {
 100         *(u32 *)data += strlen(name);
 101
 102         return 0;
 103 }
 104
 105 static void test_kallsyms_compression_ratio(void)
 106 {
 107         u32 pos, off, len, num;
 108         u32 ratio, total_size, total_len = 0;
 109
 110         kallsyms_on_each_symbol(stat_symbol_len, &total_len);
 111
 112         /*
 113          * A symbol name cannot start with a number. This stub name helps us
 114          * traverse the entire symbol table without finding a match. It's used
 115          * for subsequent performance tests, and its length is the average
 116          * length of all symbol names.
 117          */
 118         memset(stub_name, '4', sizeof(stub_name));
 119         pos = total_len / kallsyms_num_syms;
 120         stub_name[pos] = 0;
 121
 122         pos = 0;
 123         num = 0;
 124         off = 0;
 125         while (pos < kallsyms_num_syms) {
 126                 len = kallsyms_names[off];
 127                 num++;
 128                 off++;
 129                 pos++;
 130                 if ((len & 0x80) != 0) {
 131                         len = (len & 0x7f) | (kallsyms_names[off] << 7);
 132                         num++;
 133                         off++;
 134                 }
 135                 off += len;
 136         }
 137
 138         /*
 139          * 1. The length fields is not counted
 140          * 2. The memory occupied by array kallsyms_token_table[] and
 141          *    kallsyms_token_index[] needs to be counted.
 142          */
 143         total_size = off - num;
 144         pos = kallsyms_token_index[0xff];
 145         total_size += pos + strlen(&kallsyms_token_table[pos]) + 1;
 146         total_size += 0x100 * sizeof(u16);
 147
 148         pr_info(" ---------------------------------------------------------\n");
 149         pr_info("| nr_symbols | compressed size | original size | ratio(%%) |\n");
 150         pr_info("|---------------------------------------------------------|\n");
 151         ratio = (u32)div_u64(10000ULL * total_size, total_len);
 152         pr_info("| %10d |    %10d   |   %10d  |  %2d.%-2d   |\n",
 153                 kallsyms_num_syms, total_size, total_len, ratio / 100, ratio % 100);
 154         pr_info(" ---------------------------------------------------------\n");
 155 }
 156
 157 static int lookup_name(void *data, const char *name, struct module *mod, unsigned long addr)
 158 {
 159         u64 t0, t1, t;
 160         struct test_stat *stat = (struct test_stat *)data;
 161
 162         t0 = ktime_get_ns();
 163         (void)kallsyms_lookup_name(name);
 164         t1 = ktime_get_ns();
 165
 166         t = t1 - t0;
 167         if (t < stat->min)
 168                 stat->min = t;
 169
 170         if (t > stat->max)
 171                 stat->max = t;
 172
 173         stat->real_cnt++;
 174         stat->sum += t;
 175
 176         return 0;
 177 }
 178
 179 static void test_perf_kallsyms_lookup_name(void)
 180 {
 181         struct test_stat stat;
 182
 183         memset(&stat, 0, sizeof(stat));
 184         stat.min = INT_MAX;
 185         kallsyms_on_each_symbol(lookup_name, &stat);
 186         pr_info("kallsyms_lookup_name() looked up %d symbols\n", stat.real_cnt);
 187         pr_info("The time spent on each symbol is (ns): min=%d, max=%d, avg=%lld\n",
 188                 stat.min, stat.max, div_u64(stat.sum, stat.real_cnt));
 189 }
 190
 191 static bool match_cleanup_name(const char *s, const char *name)
 192 {
 193         char *p;
 194         int len;
 195
 196         if (!IS_ENABLED(CONFIG_LTO_CLANG))
 197                 return false;
 198
 199         p = strchr(s, '.');
 200         if (!p)
 201                 return false;
 202
 203         len = strlen(name);
 204         if (p - s != len)
 205                 return false;
 206
 207         return !strncmp(s, name, len);
 208 }
 209
 210 static int find_symbol(void *data, const char *name, struct module *mod, unsigned long addr)
 211 {
 212         struct test_stat *stat = (struct test_stat *)data;
 213
 214         if (strcmp(name, stat->name) == 0 ||
 215             (!stat->perf && match_cleanup_name(name, stat->name))) {
 216                 stat->real_cnt++;
 217                 stat->addr = addr;
 218
 219                 if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
 220                         stat->addrs[stat->save_cnt] = addr;
 221                         stat->save_cnt++;
 222                 }
 223
 224                 if (stat->real_cnt == stat->max)
 225                         return 1;
 226         }
 227
 228         return 0;
 229 }
 230
 231 static void test_perf_kallsyms_on_each_symbol(void)
 232 {
 233         u64 t0, t1;
 234         struct test_stat stat;
 235
 236         memset(&stat, 0, sizeof(stat));
 237         stat.max = INT_MAX;
 238         stat.name = stub_name;
 239         stat.perf = 1;
 240         t0 = ktime_get_ns();
 241         kallsyms_on_each_symbol(find_symbol, &stat);
 242         t1 = ktime_get_ns();
 243         pr_info("kallsyms_on_each_symbol() traverse all: %lld ns\n", t1 - t0);
 244 }
 245
 246 static int match_symbol(void *data, unsigned long addr)
 247 {
 248         struct test_stat *stat = (struct test_stat *)data;
 249
 250         stat->real_cnt++;
 251         stat->addr = addr;
 252
 253         if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
 254                 stat->addrs[stat->save_cnt] = addr;
 255                 stat->save_cnt++;
 256         }
 257
 258         if (stat->real_cnt == stat->max)
 259                 return 1;
 260
 261         return 0;
 262 }
 263
 264 static void test_perf_kallsyms_on_each_match_symbol(void)
 265 {
 266         u64 t0, t1;
 267         struct test_stat stat;
 268
 269         memset(&stat, 0, sizeof(stat));
 270         stat.max = INT_MAX;
 271         stat.name = stub_name;
 272         t0 = ktime_get_ns();
 273         kallsyms_on_each_match_symbol(match_symbol, stat.name, &stat);
 274         t1 = ktime_get_ns();
 275         pr_info("kallsyms_on_each_match_symbol() traverse all: %lld ns\n", t1 - t0);
 276 }
 277
 278 static int test_kallsyms_basic_function(void)
 279 {
 280         int i, j, ret;
 281         int next = 0, nr_failed = 0;
 282         char *prefix;
 283         unsigned short rand;
 284         unsigned long addr, lookup_addr;
 285         char namebuf[KSYM_NAME_LEN];
 286         struct test_stat *stat, *stat2;
 287
 288         stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
 289         if (!stat)
 290                 return -ENOMEM;
 291         stat2 = stat + 1;
 292
 293         prefix = "kallsyms_lookup_name() for";
 294         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 295                 addr = kallsyms_lookup_name(test_items[i].name);
 296                 if (addr != test_items[i].addr) {
 297                         nr_failed++;
 298                         pr_info("%s %s failed: addr=%lx, expect %lx\n",
 299                                 prefix, test_items[i].name, addr, test_items[i].addr);
 300                 }
 301         }
 302
 303         prefix = "kallsyms_on_each_symbol() for";
 304         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 305                 memset(stat, 0, sizeof(*stat));
 306                 stat->max = INT_MAX;
 307                 stat->name = test_items[i].name;
 308                 kallsyms_on_each_symbol(find_symbol, stat);
 309                 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
 310                         nr_failed++;
 311                         pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
 312                                 prefix, test_items[i].name,
 313                                 stat->real_cnt, stat->addr, test_items[i].addr);
 314                 }
 315         }
 316
 317         prefix = "kallsyms_on_each_match_symbol() for";
 318         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 319                 memset(stat, 0, sizeof(*stat));
 320                 stat->max = INT_MAX;
 321                 stat->name = test_items[i].name;
 322                 kallsyms_on_each_match_symbol(match_symbol, test_items[i].name, stat);
 323                 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
 324                         nr_failed++;
 325                         pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
 326                                 prefix, test_items[i].name,
 327                                 stat->real_cnt, stat->addr, test_items[i].addr);
 328                 }
 329         }
 330
 331         if (nr_failed) {
 332                 kfree(stat);
 333                 return -ESRCH;
 334         }
 335
 336         for (i = 0; i < kallsyms_num_syms; i++) {
 337                 addr = kallsyms_sym_address(i);
 338                 if (!is_ksym_addr(addr))
 339                         continue;
 340
 341                 ret = lookup_symbol_name(addr, namebuf);
 342                 if (unlikely(ret)) {
 343                         namebuf[0] = 0;
 344                         goto failed;
 345                 }
 346
 347                 /*
 348                  * The first '.' may be the initial letter, in which case the
 349                  * entire symbol name will be truncated to an empty string in
 350                  * cleanup_symbol_name(). Do not test these symbols.
 351                  *
 352                  * For example:
 353                  * cat /proc/kallsyms | awk '{print $3}' | grep -E "^\." | head
 354                  * .E_read_words
 355                  * .E_leading_bytes
 356                  * .E_trailing_bytes
 357                  * .E_write_words
 358                  * .E_copy
 359                  * .str.292.llvm.12122243386960820698
 360                  * .str.24.llvm.12122243386960820698
 361                  * .str.29.llvm.12122243386960820698
 362                  * .str.75.llvm.12122243386960820698
 363                  * .str.99.llvm.12122243386960820698
 364                  */
 365                 if (IS_ENABLED(CONFIG_LTO_CLANG) && !namebuf[0])
 366                         continue;
 367
 368                 lookup_addr = kallsyms_lookup_name(namebuf);
 369
 370                 memset(stat, 0, sizeof(*stat));
 371                 stat->max = INT_MAX;
 372                 kallsyms_on_each_match_symbol(match_symbol, namebuf, stat);
 373
 374                 /*
 375                  * kallsyms_on_each_symbol() is too slow, randomly select some
 376                  * symbols for test.
 377                  */
 378                 if (i >= next) {
 379                         memset(stat2, 0, sizeof(*stat2));
 380                         stat2->max = INT_MAX;
 381                         stat2->name = namebuf;
 382                         kallsyms_on_each_symbol(find_symbol, stat2);
 383
 384                         /*
 385                          * kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()
 386                          * need to get the same traversal result.
 387                          */
 388                         if (stat->addr != stat2->addr ||
 389                             stat->real_cnt != stat2->real_cnt ||
 390                             memcmp(stat->addrs, stat2->addrs,
 391                                    stat->save_cnt * sizeof(stat->addrs[0])))
 392                                 goto failed;
 393
 394                         /*
 395                          * The average of random increments is 128, that is, one of
 396                          * them is tested every 128 symbols.
 397                          */
 398                         get_random_bytes(&rand, sizeof(rand));
 399                         next = i + (rand & 0xff) + 1;
 400                 }
 401
 402                 /* Need to be found at least once */
 403                 if (!stat->real_cnt)
 404                         goto failed;
 405
 406                 /*
 407                  * kallsyms_lookup_name() returns the address of the first
 408                  * symbol found and cannot be NULL.
 409                  */
 410                 if (!lookup_addr || lookup_addr != stat->addrs[0])
 411                         goto failed;
 412
 413                 /*
 414                  * If the addresses of all matching symbols are recorded, the
 415                  * target address needs to be exist.
 416                  */
 417                 if (stat->real_cnt <= MAX_NUM_OF_RECORDS) {
 418                         for (j = 0; j < stat->save_cnt; j++) {
 419                                 if (stat->addrs[j] == addr)
 420                                         break;
 421                         }
 422
 423                         if (j == stat->save_cnt)
 424                                 goto failed;
 425                 }
 426         }
 427
 428         kfree(stat);
 429
 430         return 0;
 431
 432 failed:
 433         pr_info("Test for %dth symbol failed: (%s) addr=%lx", i, namebuf, addr);
 434         kfree(stat);
 435         return -ESRCH;
 436 }
 437
 438 static int test_entry(void *p)
 439 {
 440         int ret;
 441
 442         do {
 443                 schedule_timeout(5 * HZ);
 444         } while (system_state != SYSTEM_RUNNING);
 445
 446         pr_info("start\n");
 447         ret = test_kallsyms_basic_function();
 448         if (ret) {
 449                 pr_info("abort\n");
 450                 return 0;
 451         }
 452
 453         test_kallsyms_compression_ratio();
 454         test_perf_kallsyms_lookup_name();
 455         test_perf_kallsyms_on_each_symbol();
 456         test_perf_kallsyms_on_each_match_symbol();
 457         pr_info("finish\n");
 458
 459         return 0;
 460 }
 461
 462 static int __init kallsyms_test_init(void)
 463 {
 464         struct task_struct *t;
 465
 466         t = kthread_create(test_entry, NULL, "kallsyms_test");
 467         if (IS_ERR(t)) {
 468                 pr_info("Create kallsyms selftest task failed\n");
 469                 return PTR_ERR(t);
 470         }
 471         kthread_bind(t, 0);
 472         wake_up_process(t);
 473
 474         return 0;
 475 }
 476 late_initcall(kallsyms_test_init);