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 #endif
  93 };
  94
  95 static char stub_name[KSYM_NAME_LEN];
  96
  97 static int stat_symbol_len(void *data, const char *name, unsigned long addr)
  98 {
  99         *(u32 *)data += strlen(name);
 100
 101         return 0;
 102 }
 103
 104 static void test_kallsyms_compression_ratio(void)
 105 {
 106         u32 pos, off, len, num;
 107         u32 ratio, total_size, total_len = 0;
 108
 109         kallsyms_on_each_symbol(stat_symbol_len, &total_len);
 110
 111         /*
 112          * A symbol name cannot start with a number. This stub name helps us
 113          * traverse the entire symbol table without finding a match. It's used
 114          * for subsequent performance tests, and its length is the average
 115          * length of all symbol names.
 116          */
 117         memset(stub_name, '4', sizeof(stub_name));
 118         pos = total_len / kallsyms_num_syms;
 119         stub_name[pos] = 0;
 120
 121         pos = 0;
 122         num = 0;
 123         off = 0;
 124         while (pos < kallsyms_num_syms) {
 125                 len = kallsyms_names[off];
 126                 num++;
 127                 off++;
 128                 pos++;
 129                 if ((len & 0x80) != 0) {
 130                         len = (len & 0x7f) | (kallsyms_names[off] << 7);
 131                         num++;
 132                         off++;
 133                 }
 134                 off += len;
 135         }
 136
 137         /*
 138          * 1. The length fields is not counted
 139          * 2. The memory occupied by array kallsyms_token_table[] and
 140          *    kallsyms_token_index[] needs to be counted.
 141          */
 142         total_size = off - num;
 143         pos = kallsyms_token_index[0xff];
 144         total_size += pos + strlen(&kallsyms_token_table[pos]) + 1;
 145         total_size += 0x100 * sizeof(u16);
 146
 147         pr_info(" ---------------------------------------------------------\n");
 148         pr_info("| nr_symbols | compressed size | original size | ratio(%%) |\n");
 149         pr_info("|---------------------------------------------------------|\n");
 150         ratio = (u32)div_u64(10000ULL * total_size, total_len);
 151         pr_info("| %10d |    %10d   |   %10d  |  %2d.%-2d   |\n",
 152                 kallsyms_num_syms, total_size, total_len, ratio / 100, ratio % 100);
 153         pr_info(" ---------------------------------------------------------\n");
 154 }
 155
 156 static int lookup_name(void *data, const char *name, unsigned long addr)
 157 {
 158         u64 t0, t1, t;
 159         struct test_stat *stat = (struct test_stat *)data;
 160
 161         t0 = ktime_get_ns();
 162         (void)kallsyms_lookup_name(name);
 163         t1 = ktime_get_ns();
 164
 165         t = t1 - t0;
 166         if (t < stat->min)
 167                 stat->min = t;
 168
 169         if (t > stat->max)
 170                 stat->max = t;
 171
 172         stat->real_cnt++;
 173         stat->sum += t;
 174
 175         return 0;
 176 }
 177
 178 static void test_perf_kallsyms_lookup_name(void)
 179 {
 180         struct test_stat stat;
 181
 182         memset(&stat, 0, sizeof(stat));
 183         stat.min = INT_MAX;
 184         kallsyms_on_each_symbol(lookup_name, &stat);
 185         pr_info("kallsyms_lookup_name() looked up %d symbols\n", stat.real_cnt);
 186         pr_info("The time spent on each symbol is (ns): min=%d, max=%d, avg=%lld\n",
 187                 stat.min, stat.max, div_u64(stat.sum, stat.real_cnt));
 188 }
 189
 190 static bool match_cleanup_name(const char *s, const char *name)
 191 {
 192         char *p;
 193         int len;
 194
 195         if (!IS_ENABLED(CONFIG_LTO_CLANG))
 196                 return false;
 197
 198         p = strstr(s, ".llvm.");
 199         if (!p)
 200                 return false;
 201
 202         len = strlen(name);
 203         if (p - s != len)
 204                 return false;
 205
 206         return !strncmp(s, name, len);
 207 }
 208
 209 static int find_symbol(void *data, const char *name, unsigned long addr)
 210 {
 211         struct test_stat *stat = (struct test_stat *)data;
 212
 213         if (strcmp(name, stat->name) == 0 ||
 214             (!stat->perf && match_cleanup_name(name, stat->name))) {
 215                 stat->real_cnt++;
 216                 stat->addr = addr;
 217
 218                 if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
 219                         stat->addrs[stat->save_cnt] = addr;
 220                         stat->save_cnt++;
 221                 }
 222
 223                 if (stat->real_cnt == stat->max)
 224                         return 1;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static void test_perf_kallsyms_on_each_symbol(void)
 231 {
 232         u64 t0, t1;
 233         struct test_stat stat;
 234
 235         memset(&stat, 0, sizeof(stat));
 236         stat.max = INT_MAX;
 237         stat.name = stub_name;
 238         stat.perf = 1;
 239         t0 = ktime_get_ns();
 240         kallsyms_on_each_symbol(find_symbol, &stat);
 241         t1 = ktime_get_ns();
 242         pr_info("kallsyms_on_each_symbol() traverse all: %lld ns\n", t1 - t0);
 243 }
 244
 245 static int match_symbol(void *data, unsigned long addr)
 246 {
 247         struct test_stat *stat = (struct test_stat *)data;
 248
 249         stat->real_cnt++;
 250         stat->addr = addr;
 251
 252         if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
 253                 stat->addrs[stat->save_cnt] = addr;
 254                 stat->save_cnt++;
 255         }
 256
 257         if (stat->real_cnt == stat->max)
 258                 return 1;
 259
 260         return 0;
 261 }
 262
 263 static void test_perf_kallsyms_on_each_match_symbol(void)
 264 {
 265         u64 t0, t1;
 266         struct test_stat stat;
 267
 268         memset(&stat, 0, sizeof(stat));
 269         stat.max = INT_MAX;
 270         stat.name = stub_name;
 271         t0 = ktime_get_ns();
 272         kallsyms_on_each_match_symbol(match_symbol, stat.name, &stat);
 273         t1 = ktime_get_ns();
 274         pr_info("kallsyms_on_each_match_symbol() traverse all: %lld ns\n", t1 - t0);
 275 }
 276
 277 static int test_kallsyms_basic_function(void)
 278 {
 279         int i, j, ret;
 280         int next = 0, nr_failed = 0;
 281         char *prefix;
 282         unsigned short rand;
 283         unsigned long addr, lookup_addr;
 284         char namebuf[KSYM_NAME_LEN];
 285         struct test_stat *stat, *stat2;
 286
 287         stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
 288         if (!stat)
 289                 return -ENOMEM;
 290         stat2 = stat + 1;
 291
 292         prefix = "kallsyms_lookup_name() for";
 293         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 294                 addr = kallsyms_lookup_name(test_items[i].name);
 295                 if (addr != test_items[i].addr) {
 296                         nr_failed++;
 297                         pr_info("%s %s failed: addr=%lx, expect %lx\n",
 298                                 prefix, test_items[i].name, addr, test_items[i].addr);
 299                 }
 300         }
 301
 302         prefix = "kallsyms_on_each_symbol() for";
 303         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 304                 memset(stat, 0, sizeof(*stat));
 305                 stat->max = INT_MAX;
 306                 stat->name = test_items[i].name;
 307                 kallsyms_on_each_symbol(find_symbol, stat);
 308                 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
 309                         nr_failed++;
 310                         pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
 311                                 prefix, test_items[i].name,
 312                                 stat->real_cnt, stat->addr, test_items[i].addr);
 313                 }
 314         }
 315
 316         prefix = "kallsyms_on_each_match_symbol() for";
 317         for (i = 0; i < ARRAY_SIZE(test_items); i++) {
 318                 memset(stat, 0, sizeof(*stat));
 319                 stat->max = INT_MAX;
 320                 stat->name = test_items[i].name;
 321                 kallsyms_on_each_match_symbol(match_symbol, test_items[i].name, stat);
 322                 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
 323                         nr_failed++;
 324                         pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
 325                                 prefix, test_items[i].name,
 326                                 stat->real_cnt, stat->addr, test_items[i].addr);
 327                 }
 328         }
 329
 330         if (nr_failed) {
 331                 kfree(stat);
 332                 return -ESRCH;
 333         }
 334
 335         for (i = 0; i < kallsyms_num_syms; i++) {
 336                 addr = kallsyms_sym_address(i);
 337                 if (!is_ksym_addr(addr))
 338                         continue;
 339
 340                 ret = lookup_symbol_name(addr, namebuf);
 341                 if (unlikely(ret)) {
 342                         namebuf[0] = 0;
 343                         pr_info("%d: lookup_symbol_name(%lx) failed\n", i, addr);
 344                         goto failed;
 345                 }
 346
 347                 lookup_addr = kallsyms_lookup_name(namebuf);
 348
 349                 memset(stat, 0, sizeof(*stat));
 350                 stat->max = INT_MAX;
 351                 kallsyms_on_each_match_symbol(match_symbol, namebuf, stat);
 352
 353                 /*
 354                  * kallsyms_on_each_symbol() is too slow, randomly select some
 355                  * symbols for test.
 356                  */
 357                 if (i >= next) {
 358                         memset(stat2, 0, sizeof(*stat2));
 359                         stat2->max = INT_MAX;
 360                         stat2->name = namebuf;
 361                         kallsyms_on_each_symbol(find_symbol, stat2);
 362
 363                         /*
 364                          * kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()
 365                          * need to get the same traversal result.
 366                          */
 367                         if (stat->addr != stat2->addr ||
 368                             stat->real_cnt != stat2->real_cnt ||
 369                             memcmp(stat->addrs, stat2->addrs,
 370                                    stat->save_cnt * sizeof(stat->addrs[0]))) {
 371                                 pr_info("%s: mismatch between kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()\n",
 372                                         namebuf);
 373                                 goto failed;
 374                         }
 375
 376                         /*
 377                          * The average of random increments is 128, that is, one of
 378                          * them is tested every 128 symbols.
 379                          */
 380                         get_random_bytes(&rand, sizeof(rand));
 381                         next = i + (rand & 0xff) + 1;
 382                 }
 383
 384                 /* Need to be found at least once */
 385                 if (!stat->real_cnt) {
 386                         pr_info("%s: Never found\n", namebuf);
 387                         goto failed;
 388                 }
 389
 390                 /*
 391                  * kallsyms_lookup_name() returns the address of the first
 392                  * symbol found and cannot be NULL.
 393                  */
 394                 if (!lookup_addr) {
 395                         pr_info("%s: NULL lookup_addr?!\n", namebuf);
 396                         goto failed;
 397                 }
 398                 if (lookup_addr != stat->addrs[0]) {
 399                         pr_info("%s: lookup_addr != stat->addrs[0]\n", namebuf);
 400                         goto failed;
 401                 }
 402
 403                 /*
 404                  * If the addresses of all matching symbols are recorded, the
 405                  * target address needs to be exist.
 406                  */
 407                 if (stat->real_cnt <= MAX_NUM_OF_RECORDS) {
 408                         for (j = 0; j < stat->save_cnt; j++) {
 409                                 if (stat->addrs[j] == addr)
 410                                         break;
 411                         }
 412
 413                         if (j == stat->save_cnt) {
 414                                 pr_info("%s: j == save_cnt?!\n", namebuf);
 415                                 goto failed;
 416                         }
 417                 }
 418         }
 419
 420         kfree(stat);
 421
 422         return 0;
 423
 424 failed:
 425         pr_info("Test for %dth symbol failed: (%s) addr=%lx", i, namebuf, addr);
 426         kfree(stat);
 427         return -ESRCH;
 428 }
 429
 430 static int test_entry(void *p)
 431 {
 432         int ret;
 433
 434         do {
 435                 schedule_timeout(5 * HZ);
 436         } while (system_state != SYSTEM_RUNNING);
 437
 438         pr_info("start\n");
 439         ret = test_kallsyms_basic_function();
 440         if (ret) {
 441                 pr_info("abort\n");
 442                 return 0;
 443         }
 444
 445         test_kallsyms_compression_ratio();
 446         test_perf_kallsyms_lookup_name();
 447         test_perf_kallsyms_on_each_symbol();
 448         test_perf_kallsyms_on_each_match_symbol();
 449         pr_info("finish\n");
 450
 451         return 0;
 452 }
 453
 454 static int __init kallsyms_test_init(void)
 455 {
 456         struct task_struct *t;
 457
 458         t = kthread_create(test_entry, NULL, "kallsyms_test");
 459         if (IS_ERR(t)) {
 460                 pr_info("Create kallsyms selftest task failed\n");
 461                 return PTR_ERR(t);
 462         }
 463         kthread_bind(t, 0);
 464         wake_up_process(t);
 465
 466         return 0;
 467 }
 468 late_initcall(kallsyms_test_init);