1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * test_kprobes.c - simple sanity test for k*probes
4 *
5 * Copyright IBM Corp. 2008
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/kprobes.h>
10 #include <linux/random.h>
11 #include <kunit/test.h>
12
13 #define div_factor 3
14
15 static u32 rand1, preh_val, posth_val;
16 static u32 (*target)(u32 value);
17 static u32 (*recursed_target)(u32 value);
18 static u32 (*target2)(u32 value);
19 static struct kunit *current_test;
20
21 static unsigned long (*internal_target)(void);
22 static unsigned long (*stacktrace_target)(void);
23 static unsigned long (*stacktrace_driver)(void);
24 static unsigned long target_return_address[2];
25
kprobe_target(u32 value)26 static noinline u32 kprobe_target(u32 value)
27 {
28 return (value / div_factor);
29 }
30
kprobe_recursed_target(u32 value)31 static noinline u32 kprobe_recursed_target(u32 value)
32 {
33 return (value / div_factor);
34 }
35
kp_pre_handler(struct kprobe * p,struct pt_regs * regs)36 static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
37 {
38 KUNIT_EXPECT_FALSE(current_test, preemptible());
39
40 preh_val = recursed_target(rand1);
41 return 0;
42 }
43
kp_post_handler(struct kprobe * p,struct pt_regs * regs,unsigned long flags)44 static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
45 unsigned long flags)
46 {
47 u32 expval = recursed_target(rand1);
48
49 KUNIT_EXPECT_FALSE(current_test, preemptible());
50 KUNIT_EXPECT_EQ(current_test, preh_val, expval);
51
52 posth_val = preh_val + div_factor;
53 }
54
55 static struct kprobe kp = {
56 .symbol_name = "kprobe_target",
57 .pre_handler = kp_pre_handler,
58 .post_handler = kp_post_handler
59 };
60
test_kprobe(struct kunit * test)61 static void test_kprobe(struct kunit *test)
62 {
63 current_test = test;
64 KUNIT_EXPECT_EQ(test, 0, register_kprobe(&kp));
65 target(rand1);
66 unregister_kprobe(&kp);
67 KUNIT_EXPECT_NE(test, 0, preh_val);
68 KUNIT_EXPECT_NE(test, 0, posth_val);
69 }
70
kprobe_target2(u32 value)71 static noinline u32 kprobe_target2(u32 value)
72 {
73 return (value / div_factor) + 1;
74 }
75
kprobe_stacktrace_internal_target(void)76 static noinline unsigned long kprobe_stacktrace_internal_target(void)
77 {
78 if (!target_return_address[0])
79 target_return_address[0] = (unsigned long)__builtin_return_address(0);
80 return target_return_address[0];
81 }
82
kprobe_stacktrace_target(void)83 static noinline unsigned long kprobe_stacktrace_target(void)
84 {
85 if (!target_return_address[1])
86 target_return_address[1] = (unsigned long)__builtin_return_address(0);
87
88 if (internal_target)
89 internal_target();
90
91 return target_return_address[1];
92 }
93
kprobe_stacktrace_driver(void)94 static noinline unsigned long kprobe_stacktrace_driver(void)
95 {
96 if (stacktrace_target)
97 stacktrace_target();
98
99 /* This is for preventing inlining the function */
100 return (unsigned long)__builtin_return_address(0);
101 }
102
kp_pre_handler2(struct kprobe * p,struct pt_regs * regs)103 static int kp_pre_handler2(struct kprobe *p, struct pt_regs *regs)
104 {
105 preh_val = (rand1 / div_factor) + 1;
106 return 0;
107 }
108
kp_post_handler2(struct kprobe * p,struct pt_regs * regs,unsigned long flags)109 static void kp_post_handler2(struct kprobe *p, struct pt_regs *regs,
110 unsigned long flags)
111 {
112 KUNIT_EXPECT_EQ(current_test, preh_val, (rand1 / div_factor) + 1);
113 posth_val = preh_val + div_factor;
114 }
115
116 static struct kprobe kp2 = {
117 .symbol_name = "kprobe_target2",
118 .pre_handler = kp_pre_handler2,
119 .post_handler = kp_post_handler2
120 };
121
test_kprobes(struct kunit * test)122 static void test_kprobes(struct kunit *test)
123 {
124 struct kprobe *kps[2] = {&kp, &kp2};
125
126 current_test = test;
127
128 /* addr and flags should be cleard for reusing kprobe. */
129 kp.addr = NULL;
130 kp.flags = 0;
131
132 KUNIT_EXPECT_EQ(test, 0, register_kprobes(kps, 2));
133 preh_val = 0;
134 posth_val = 0;
135 target(rand1);
136
137 KUNIT_EXPECT_NE(test, 0, preh_val);
138 KUNIT_EXPECT_NE(test, 0, posth_val);
139
140 preh_val = 0;
141 posth_val = 0;
142 target2(rand1);
143
144 KUNIT_EXPECT_NE(test, 0, preh_val);
145 KUNIT_EXPECT_NE(test, 0, posth_val);
146 unregister_kprobes(kps, 2);
147 }
148
149 static struct kprobe kp_missed = {
150 .symbol_name = "kprobe_recursed_target",
151 .pre_handler = kp_pre_handler,
152 .post_handler = kp_post_handler,
153 };
154
test_kprobe_missed(struct kunit * test)155 static void test_kprobe_missed(struct kunit *test)
156 {
157 current_test = test;
158 preh_val = 0;
159 posth_val = 0;
160
161 KUNIT_EXPECT_EQ(test, 0, register_kprobe(&kp_missed));
162
163 recursed_target(rand1);
164
165 KUNIT_EXPECT_EQ(test, 2, kp_missed.nmissed);
166 KUNIT_EXPECT_NE(test, 0, preh_val);
167 KUNIT_EXPECT_NE(test, 0, posth_val);
168
169 unregister_kprobe(&kp_missed);
170 }
171
172 #ifdef CONFIG_KRETPROBES
173 static u32 krph_val;
174
entry_handler(struct kretprobe_instance * ri,struct pt_regs * regs)175 static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
176 {
177 KUNIT_EXPECT_FALSE(current_test, preemptible());
178 krph_val = (rand1 / div_factor);
179 return 0;
180 }
181
return_handler(struct kretprobe_instance * ri,struct pt_regs * regs)182 static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
183 {
184 unsigned long ret = regs_return_value(regs);
185
186 KUNIT_EXPECT_FALSE(current_test, preemptible());
187 KUNIT_EXPECT_EQ(current_test, ret, rand1 / div_factor);
188 KUNIT_EXPECT_NE(current_test, krph_val, 0);
189 krph_val = rand1;
190 return 0;
191 }
192
193 static struct kretprobe rp = {
194 .handler = return_handler,
195 .entry_handler = entry_handler,
196 .kp.symbol_name = "kprobe_target"
197 };
198
test_kretprobe(struct kunit * test)199 static void test_kretprobe(struct kunit *test)
200 {
201 current_test = test;
202 KUNIT_EXPECT_EQ(test, 0, register_kretprobe(&rp));
203 target(rand1);
204 unregister_kretprobe(&rp);
205 KUNIT_EXPECT_EQ(test, krph_val, rand1);
206 }
207
return_handler2(struct kretprobe_instance * ri,struct pt_regs * regs)208 static int return_handler2(struct kretprobe_instance *ri, struct pt_regs *regs)
209 {
210 unsigned long ret = regs_return_value(regs);
211
212 KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1);
213 KUNIT_EXPECT_NE(current_test, krph_val, 0);
214 krph_val = rand1;
215 return 0;
216 }
217
218 static struct kretprobe rp2 = {
219 .handler = return_handler2,
220 .entry_handler = entry_handler,
221 .kp.symbol_name = "kprobe_target2"
222 };
223
test_kretprobes(struct kunit * test)224 static void test_kretprobes(struct kunit *test)
225 {
226 struct kretprobe *rps[2] = {&rp, &rp2};
227
228 current_test = test;
229 /* addr and flags should be cleard for reusing kprobe. */
230 rp.kp.addr = NULL;
231 rp.kp.flags = 0;
232 KUNIT_EXPECT_EQ(test, 0, register_kretprobes(rps, 2));
233
234 krph_val = 0;
235 target(rand1);
236 KUNIT_EXPECT_EQ(test, krph_val, rand1);
237
238 krph_val = 0;
239 target2(rand1);
240 KUNIT_EXPECT_EQ(test, krph_val, rand1);
241 unregister_kretprobes(rps, 2);
242 }
243
244 #ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
245 #define STACK_BUF_SIZE 16
246 static unsigned long stack_buf[STACK_BUF_SIZE];
247
stacktrace_return_handler(struct kretprobe_instance * ri,struct pt_regs * regs)248 static int stacktrace_return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
249 {
250 unsigned long retval = regs_return_value(regs);
251 int i, ret;
252
253 KUNIT_EXPECT_FALSE(current_test, preemptible());
254 KUNIT_EXPECT_EQ(current_test, retval, target_return_address[1]);
255
256 /*
257 * Test stacktrace inside the kretprobe handler, this will involves
258 * kretprobe trampoline, but must include correct return address
259 * of the target function.
260 */
261 ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0);
262 KUNIT_EXPECT_NE(current_test, ret, 0);
263
264 for (i = 0; i < ret; i++) {
265 if (stack_buf[i] == target_return_address[1])
266 break;
267 }
268 KUNIT_EXPECT_NE(current_test, i, ret);
269
270 #if !IS_MODULE(CONFIG_KPROBES_SANITY_TEST)
271 /*
272 * Test stacktrace from pt_regs at the return address. Thus the stack
273 * trace must start from the target return address.
274 */
275 ret = stack_trace_save_regs(regs, stack_buf, STACK_BUF_SIZE, 0);
276 KUNIT_EXPECT_NE(current_test, ret, 0);
277 KUNIT_EXPECT_EQ(current_test, stack_buf[0], target_return_address[1]);
278 #endif
279
280 return 0;
281 }
282
283 static struct kretprobe rp3 = {
284 .handler = stacktrace_return_handler,
285 .kp.symbol_name = "kprobe_stacktrace_target"
286 };
287
test_stacktrace_on_kretprobe(struct kunit * test)288 static void test_stacktrace_on_kretprobe(struct kunit *test)
289 {
290 unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
291
292 current_test = test;
293 rp3.kp.addr = NULL;
294 rp3.kp.flags = 0;
295
296 /*
297 * Run the stacktrace_driver() to record correct return address in
298 * stacktrace_target() and ensure stacktrace_driver() call is not
299 * inlined by checking the return address of stacktrace_driver()
300 * and the return address of this function is different.
301 */
302 KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
303
304 KUNIT_ASSERT_EQ(test, 0, register_kretprobe(&rp3));
305 KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
306 unregister_kretprobe(&rp3);
307 }
308
stacktrace_internal_return_handler(struct kretprobe_instance * ri,struct pt_regs * regs)309 static int stacktrace_internal_return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
310 {
311 unsigned long retval = regs_return_value(regs);
312 int i, ret;
313
314 KUNIT_EXPECT_FALSE(current_test, preemptible());
315 KUNIT_EXPECT_EQ(current_test, retval, target_return_address[0]);
316
317 /*
318 * Test stacktrace inside the kretprobe handler for nested case.
319 * The unwinder will find the kretprobe_trampoline address on the
320 * return address, and kretprobe must solve that.
321 */
322 ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0);
323 KUNIT_EXPECT_NE(current_test, ret, 0);
324
325 for (i = 0; i < ret - 1; i++) {
326 if (stack_buf[i] == target_return_address[0]) {
327 KUNIT_EXPECT_EQ(current_test, stack_buf[i + 1], target_return_address[1]);
328 break;
329 }
330 }
331 KUNIT_EXPECT_NE(current_test, i, ret);
332
333 #if !IS_MODULE(CONFIG_KPROBES_SANITY_TEST)
334 /* Ditto for the regs version. */
335 ret = stack_trace_save_regs(regs, stack_buf, STACK_BUF_SIZE, 0);
336 KUNIT_EXPECT_NE(current_test, ret, 0);
337 KUNIT_EXPECT_EQ(current_test, stack_buf[0], target_return_address[0]);
338 KUNIT_EXPECT_EQ(current_test, stack_buf[1], target_return_address[1]);
339 #endif
340
341 return 0;
342 }
343
344 static struct kretprobe rp4 = {
345 .handler = stacktrace_internal_return_handler,
346 .kp.symbol_name = "kprobe_stacktrace_internal_target"
347 };
348
test_stacktrace_on_nested_kretprobe(struct kunit * test)349 static void test_stacktrace_on_nested_kretprobe(struct kunit *test)
350 {
351 unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
352 struct kretprobe *rps[2] = {&rp3, &rp4};
353
354 current_test = test;
355 rp3.kp.addr = NULL;
356 rp3.kp.flags = 0;
357
358 //KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
359
360 KUNIT_ASSERT_EQ(test, 0, register_kretprobes(rps, 2));
361 KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
362 unregister_kretprobes(rps, 2);
363 }
364 #endif /* CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE */
365
366 #endif /* CONFIG_KRETPROBES */
367
kprobes_test_init(struct kunit * test)368 static int kprobes_test_init(struct kunit *test)
369 {
370 target = kprobe_target;
371 target2 = kprobe_target2;
372 recursed_target = kprobe_recursed_target;
373 stacktrace_target = kprobe_stacktrace_target;
374 internal_target = kprobe_stacktrace_internal_target;
375 stacktrace_driver = kprobe_stacktrace_driver;
376 rand1 = get_random_u32_above(div_factor);
377 return 0;
378 }
379
380 static struct kunit_case kprobes_testcases[] = {
381 KUNIT_CASE(test_kprobe),
382 KUNIT_CASE(test_kprobes),
383 KUNIT_CASE(test_kprobe_missed),
384 #ifdef CONFIG_KRETPROBES
385 KUNIT_CASE(test_kretprobe),
386 KUNIT_CASE(test_kretprobes),
387 #ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
388 KUNIT_CASE(test_stacktrace_on_kretprobe),
389 KUNIT_CASE(test_stacktrace_on_nested_kretprobe),
390 #endif
391 #endif
392 {}
393 };
394
395 static struct kunit_suite kprobes_test_suite = {
396 .name = "kprobes_test",
397 .init = kprobes_test_init,
398 .test_cases = kprobes_testcases,
399 };
400
401 kunit_test_suites(&kprobes_test_suite);
402
403 MODULE_DESCRIPTION("simple sanity test for k*probes");
404 MODULE_LICENSE("GPL");
405