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
26struct 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
38struct 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
56static int kallsyms_test_var_bss_static;
57static int kallsyms_test_var_data_static = 1;
58int kallsyms_test_var_bss;
59int kallsyms_test_var_data = 1;
60
61static 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
69int 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
81static 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_noprof),
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
95static char stub_name[KSYM_NAME_LEN];
96
97static int stat_symbol_len(void *data, const char *name, unsigned long addr)
98{
99 *(u32 *)data += strlen(name);
100
101 return 0;
102}
103
104static 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(fn: stat_symbol_len, data: &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(dividend: 10000ULL * total_size, divisor: 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
156static 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
178static 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(fn: lookup_name, data: &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
190static int find_symbol(void *data, const char *name, unsigned long addr)
191{
192 struct test_stat *stat = (struct test_stat *)data;
193
194 if (!strcmp(name, stat->name)) {
195 stat->real_cnt++;
196 stat->addr = addr;
197
198 if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
199 stat->addrs[stat->save_cnt] = addr;
200 stat->save_cnt++;
201 }
202
203 if (stat->real_cnt == stat->max)
204 return 1;
205 }
206
207 return 0;
208}
209
210static void test_perf_kallsyms_on_each_symbol(void)
211{
212 u64 t0, t1;
213 struct test_stat stat;
214
215 memset(&stat, 0, sizeof(stat));
216 stat.max = INT_MAX;
217 stat.name = stub_name;
218 stat.perf = 1;
219 t0 = ktime_get_ns();
220 kallsyms_on_each_symbol(fn: find_symbol, data: &stat);
221 t1 = ktime_get_ns();
222 pr_info("kallsyms_on_each_symbol() traverse all: %lld ns\n", t1 - t0);
223}
224
225static int match_symbol(void *data, unsigned long addr)
226{
227 struct test_stat *stat = (struct test_stat *)data;
228
229 stat->real_cnt++;
230 stat->addr = addr;
231
232 if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
233 stat->addrs[stat->save_cnt] = addr;
234 stat->save_cnt++;
235 }
236
237 if (stat->real_cnt == stat->max)
238 return 1;
239
240 return 0;
241}
242
243static void test_perf_kallsyms_on_each_match_symbol(void)
244{
245 u64 t0, t1;
246 struct test_stat stat;
247
248 memset(&stat, 0, sizeof(stat));
249 stat.max = INT_MAX;
250 stat.name = stub_name;
251 t0 = ktime_get_ns();
252 kallsyms_on_each_match_symbol(fn: match_symbol, name: stat.name, data: &stat);
253 t1 = ktime_get_ns();
254 pr_info("kallsyms_on_each_match_symbol() traverse all: %lld ns\n", t1 - t0);
255}
256
257static int test_kallsyms_basic_function(void)
258{
259 int i, j, ret;
260 int next = 0, nr_failed = 0;
261 char *prefix;
262 unsigned short rand;
263 unsigned long addr, lookup_addr;
264 char namebuf[KSYM_NAME_LEN];
265 struct test_stat *stat, *stat2;
266
267 stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
268 if (!stat)
269 return -ENOMEM;
270 stat2 = stat + 1;
271
272 prefix = "kallsyms_lookup_name() for";
273 for (i = 0; i < ARRAY_SIZE(test_items); i++) {
274 addr = kallsyms_lookup_name(name: test_items[i].name);
275 if (addr != test_items[i].addr) {
276 nr_failed++;
277 pr_info("%s %s failed: addr=%lx, expect %lx\n",
278 prefix, test_items[i].name, addr, test_items[i].addr);
279 }
280 }
281
282 prefix = "kallsyms_on_each_symbol() for";
283 for (i = 0; i < ARRAY_SIZE(test_items); i++) {
284 memset(stat, 0, sizeof(*stat));
285 stat->max = INT_MAX;
286 stat->name = test_items[i].name;
287 kallsyms_on_each_symbol(fn: find_symbol, data: stat);
288 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
289 nr_failed++;
290 pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
291 prefix, test_items[i].name,
292 stat->real_cnt, stat->addr, test_items[i].addr);
293 }
294 }
295
296 prefix = "kallsyms_on_each_match_symbol() for";
297 for (i = 0; i < ARRAY_SIZE(test_items); i++) {
298 memset(stat, 0, sizeof(*stat));
299 stat->max = INT_MAX;
300 stat->name = test_items[i].name;
301 kallsyms_on_each_match_symbol(fn: match_symbol, name: test_items[i].name, data: stat);
302 if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
303 nr_failed++;
304 pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
305 prefix, test_items[i].name,
306 stat->real_cnt, stat->addr, test_items[i].addr);
307 }
308 }
309
310 if (nr_failed) {
311 kfree(objp: stat);
312 return -ESRCH;
313 }
314
315 for (i = 0; i < kallsyms_num_syms; i++) {
316 addr = kallsyms_sym_address(idx: i);
317 if (!is_ksym_addr(addr))
318 continue;
319
320 ret = lookup_symbol_name(addr, symname: namebuf);
321 if (unlikely(ret)) {
322 namebuf[0] = 0;
323 pr_info("%d: lookup_symbol_name(%lx) failed\n", i, addr);
324 goto failed;
325 }
326
327 lookup_addr = kallsyms_lookup_name(name: namebuf);
328
329 memset(stat, 0, sizeof(*stat));
330 stat->max = INT_MAX;
331 kallsyms_on_each_match_symbol(fn: match_symbol, name: namebuf, data: stat);
332
333 /*
334 * kallsyms_on_each_symbol() is too slow, randomly select some
335 * symbols for test.
336 */
337 if (i >= next) {
338 memset(stat2, 0, sizeof(*stat2));
339 stat2->max = INT_MAX;
340 stat2->name = namebuf;
341 kallsyms_on_each_symbol(fn: find_symbol, data: stat2);
342
343 /*
344 * kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()
345 * need to get the same traversal result.
346 */
347 if (stat->addr != stat2->addr ||
348 stat->real_cnt != stat2->real_cnt ||
349 memcmp(p: stat->addrs, q: stat2->addrs,
350 size: stat->save_cnt * sizeof(stat->addrs[0]))) {
351 pr_info("%s: mismatch between kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()\n",
352 namebuf);
353 goto failed;
354 }
355
356 /*
357 * The average of random increments is 128, that is, one of
358 * them is tested every 128 symbols.
359 */
360 get_random_bytes(buf: &rand, len: sizeof(rand));
361 next = i + (rand & 0xff) + 1;
362 }
363
364 /* Need to be found at least once */
365 if (!stat->real_cnt) {
366 pr_info("%s: Never found\n", namebuf);
367 goto failed;
368 }
369
370 /*
371 * kallsyms_lookup_name() returns the address of the first
372 * symbol found and cannot be NULL.
373 */
374 if (!lookup_addr) {
375 pr_info("%s: NULL lookup_addr?!\n", namebuf);
376 goto failed;
377 }
378 if (lookup_addr != stat->addrs[0]) {
379 pr_info("%s: lookup_addr != stat->addrs[0]\n", namebuf);
380 goto failed;
381 }
382
383 /*
384 * If the addresses of all matching symbols are recorded, the
385 * target address needs to be exist.
386 */
387 if (stat->real_cnt <= MAX_NUM_OF_RECORDS) {
388 for (j = 0; j < stat->save_cnt; j++) {
389 if (stat->addrs[j] == addr)
390 break;
391 }
392
393 if (j == stat->save_cnt) {
394 pr_info("%s: j == save_cnt?!\n", namebuf);
395 goto failed;
396 }
397 }
398 }
399
400 kfree(objp: stat);
401
402 return 0;
403
404failed:
405 pr_info("Test for %dth symbol failed: (%s) addr=%lx", i, namebuf, addr);
406 kfree(objp: stat);
407 return -ESRCH;
408}
409
410static int test_entry(void *p)
411{
412 int ret;
413
414 do {
415 schedule_timeout(timeout: 5 * HZ);
416 } while (system_state != SYSTEM_RUNNING);
417
418 pr_info("start\n");
419 ret = test_kallsyms_basic_function();
420 if (ret) {
421 pr_info("abort\n");
422 return 0;
423 }
424
425 test_kallsyms_compression_ratio();
426 test_perf_kallsyms_lookup_name();
427 test_perf_kallsyms_on_each_symbol();
428 test_perf_kallsyms_on_each_match_symbol();
429 pr_info("finish\n");
430
431 return 0;
432}
433
434static int __init kallsyms_test_init(void)
435{
436 struct task_struct *t;
437
438 t = kthread_run_on_cpu(threadfn: test_entry, NULL, cpu: 0, namefmt: "kallsyms_test");
439 if (IS_ERR(ptr: t)) {
440 pr_info("Create kallsyms selftest task failed\n");
441 return PTR_ERR(ptr: t);
442 }
443
444 return 0;
445}
446late_initcall(kallsyms_test_init);
447

source code of linux/kernel/kallsyms_selftest.c