1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * KCSAN short boot-time selftests. |
4 | * |
5 | * Copyright (C) 2019, Google LLC. |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) "kcsan: " fmt |
9 | |
10 | #include <linux/atomic.h> |
11 | #include <linux/bitops.h> |
12 | #include <linux/init.h> |
13 | #include <linux/kcsan-checks.h> |
14 | #include <linux/kernel.h> |
15 | #include <linux/printk.h> |
16 | #include <linux/random.h> |
17 | #include <linux/sched.h> |
18 | #include <linux/spinlock.h> |
19 | #include <linux/types.h> |
20 | |
21 | #include "encoding.h" |
22 | |
23 | #define ITERS_PER_TEST 2000 |
24 | |
25 | /* |
26 | * Test watchpoint encode and decode: check that encoding some access's info, |
27 | * and then subsequent decode preserves the access's info. |
28 | */ |
29 | static bool __init test_encode_decode(void) |
30 | { |
31 | int i; |
32 | |
33 | for (i = 0; i < ITERS_PER_TEST; ++i) { |
34 | size_t size = get_random_u32_inclusive(floor: 1, MAX_ENCODABLE_SIZE); |
35 | bool is_write = !!get_random_u32_below(ceil: 2); |
36 | unsigned long verif_masked_addr; |
37 | long encoded_watchpoint; |
38 | bool verif_is_write; |
39 | unsigned long addr; |
40 | size_t verif_size; |
41 | |
42 | get_random_bytes(buf: &addr, len: sizeof(addr)); |
43 | if (addr < PAGE_SIZE) |
44 | addr = PAGE_SIZE; |
45 | |
46 | if (WARN_ON(!check_encodable(addr, size))) |
47 | return false; |
48 | |
49 | encoded_watchpoint = encode_watchpoint(addr, size, is_write); |
50 | |
51 | /* Check special watchpoints */ |
52 | if (WARN_ON(decode_watchpoint(INVALID_WATCHPOINT, &verif_masked_addr, &verif_size, &verif_is_write))) |
53 | return false; |
54 | if (WARN_ON(decode_watchpoint(CONSUMED_WATCHPOINT, &verif_masked_addr, &verif_size, &verif_is_write))) |
55 | return false; |
56 | |
57 | /* Check decoding watchpoint returns same data */ |
58 | if (WARN_ON(!decode_watchpoint(encoded_watchpoint, &verif_masked_addr, &verif_size, &verif_is_write))) |
59 | return false; |
60 | if (WARN_ON(verif_masked_addr != (addr & WATCHPOINT_ADDR_MASK))) |
61 | goto fail; |
62 | if (WARN_ON(verif_size != size)) |
63 | goto fail; |
64 | if (WARN_ON(is_write != verif_is_write)) |
65 | goto fail; |
66 | |
67 | continue; |
68 | fail: |
69 | pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n" , |
70 | __func__, is_write ? "write" : "read" , size, addr, encoded_watchpoint, |
71 | verif_is_write ? "write" : "read" , verif_size, verif_masked_addr); |
72 | return false; |
73 | } |
74 | |
75 | return true; |
76 | } |
77 | |
78 | /* Test access matching function. */ |
79 | static bool __init test_matching_access(void) |
80 | { |
81 | if (WARN_ON(!matching_access(10, 1, 10, 1))) |
82 | return false; |
83 | if (WARN_ON(!matching_access(10, 2, 11, 1))) |
84 | return false; |
85 | if (WARN_ON(!matching_access(10, 1, 9, 2))) |
86 | return false; |
87 | if (WARN_ON(matching_access(10, 1, 11, 1))) |
88 | return false; |
89 | if (WARN_ON(matching_access(9, 1, 10, 1))) |
90 | return false; |
91 | |
92 | /* |
93 | * An access of size 0 could match another access, as demonstrated here. |
94 | * Rather than add more comparisons to 'matching_access()', which would |
95 | * end up in the fast-path for *all* checks, check_access() simply |
96 | * returns for all accesses of size 0. |
97 | */ |
98 | if (WARN_ON(!matching_access(8, 8, 12, 0))) |
99 | return false; |
100 | |
101 | return true; |
102 | } |
103 | |
104 | /* |
105 | * Correct memory barrier instrumentation is critical to avoiding false |
106 | * positives: simple test to check at boot certain barriers are always properly |
107 | * instrumented. See kcsan_test for a more complete test. |
108 | */ |
109 | static DEFINE_SPINLOCK(test_spinlock); |
110 | static bool __init test_barrier(void) |
111 | { |
112 | #ifdef CONFIG_KCSAN_WEAK_MEMORY |
113 | struct kcsan_scoped_access *reorder_access = ¤t->kcsan_ctx.reorder_access; |
114 | #else |
115 | struct kcsan_scoped_access *reorder_access = NULL; |
116 | #endif |
117 | bool ret = true; |
118 | arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED; |
119 | atomic_t dummy; |
120 | long test_var; |
121 | |
122 | if (!reorder_access || !IS_ENABLED(CONFIG_SMP)) |
123 | return true; |
124 | |
125 | #define __KCSAN_CHECK_BARRIER(access_type, barrier, name) \ |
126 | do { \ |
127 | reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \ |
128 | reorder_access->size = 1; \ |
129 | barrier; \ |
130 | if (reorder_access->size != 0) { \ |
131 | pr_err("improperly instrumented type=(" #access_type "): " name "\n"); \ |
132 | ret = false; \ |
133 | } \ |
134 | } while (0) |
135 | #define KCSAN_CHECK_READ_BARRIER(b) __KCSAN_CHECK_BARRIER(0, b, #b) |
136 | #define KCSAN_CHECK_WRITE_BARRIER(b) __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE, b, #b) |
137 | #define KCSAN_CHECK_RW_BARRIER(b) __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND, b, #b) |
138 | |
139 | kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */ |
140 | |
141 | KCSAN_CHECK_READ_BARRIER(mb()); |
142 | KCSAN_CHECK_READ_BARRIER(rmb()); |
143 | KCSAN_CHECK_READ_BARRIER(smp_mb()); |
144 | KCSAN_CHECK_READ_BARRIER(smp_rmb()); |
145 | KCSAN_CHECK_READ_BARRIER(dma_rmb()); |
146 | KCSAN_CHECK_READ_BARRIER(smp_mb__before_atomic()); |
147 | KCSAN_CHECK_READ_BARRIER(smp_mb__after_atomic()); |
148 | KCSAN_CHECK_READ_BARRIER(smp_mb__after_spinlock()); |
149 | KCSAN_CHECK_READ_BARRIER(smp_store_mb(test_var, 0)); |
150 | KCSAN_CHECK_READ_BARRIER(smp_store_release(&test_var, 0)); |
151 | KCSAN_CHECK_READ_BARRIER(xchg(&test_var, 0)); |
152 | KCSAN_CHECK_READ_BARRIER(xchg_release(&test_var, 0)); |
153 | KCSAN_CHECK_READ_BARRIER(cmpxchg(&test_var, 0, 0)); |
154 | KCSAN_CHECK_READ_BARRIER(cmpxchg_release(&test_var, 0, 0)); |
155 | KCSAN_CHECK_READ_BARRIER(atomic_set_release(&dummy, 0)); |
156 | KCSAN_CHECK_READ_BARRIER(atomic_add_return(1, &dummy)); |
157 | KCSAN_CHECK_READ_BARRIER(atomic_add_return_release(1, &dummy)); |
158 | KCSAN_CHECK_READ_BARRIER(atomic_fetch_add(1, &dummy)); |
159 | KCSAN_CHECK_READ_BARRIER(atomic_fetch_add_release(1, &dummy)); |
160 | KCSAN_CHECK_READ_BARRIER(test_and_set_bit(0, &test_var)); |
161 | KCSAN_CHECK_READ_BARRIER(test_and_clear_bit(0, &test_var)); |
162 | KCSAN_CHECK_READ_BARRIER(test_and_change_bit(0, &test_var)); |
163 | KCSAN_CHECK_READ_BARRIER(clear_bit_unlock(0, &test_var)); |
164 | KCSAN_CHECK_READ_BARRIER(__clear_bit_unlock(0, &test_var)); |
165 | arch_spin_lock(&arch_spinlock); |
166 | KCSAN_CHECK_READ_BARRIER(arch_spin_unlock(&arch_spinlock)); |
167 | spin_lock(lock: &test_spinlock); |
168 | KCSAN_CHECK_READ_BARRIER(spin_unlock(&test_spinlock)); |
169 | |
170 | KCSAN_CHECK_WRITE_BARRIER(mb()); |
171 | KCSAN_CHECK_WRITE_BARRIER(wmb()); |
172 | KCSAN_CHECK_WRITE_BARRIER(smp_mb()); |
173 | KCSAN_CHECK_WRITE_BARRIER(smp_wmb()); |
174 | KCSAN_CHECK_WRITE_BARRIER(dma_wmb()); |
175 | KCSAN_CHECK_WRITE_BARRIER(smp_mb__before_atomic()); |
176 | KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_atomic()); |
177 | KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_spinlock()); |
178 | KCSAN_CHECK_WRITE_BARRIER(smp_store_mb(test_var, 0)); |
179 | KCSAN_CHECK_WRITE_BARRIER(smp_store_release(&test_var, 0)); |
180 | KCSAN_CHECK_WRITE_BARRIER(xchg(&test_var, 0)); |
181 | KCSAN_CHECK_WRITE_BARRIER(xchg_release(&test_var, 0)); |
182 | KCSAN_CHECK_WRITE_BARRIER(cmpxchg(&test_var, 0, 0)); |
183 | KCSAN_CHECK_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0)); |
184 | KCSAN_CHECK_WRITE_BARRIER(atomic_set_release(&dummy, 0)); |
185 | KCSAN_CHECK_WRITE_BARRIER(atomic_add_return(1, &dummy)); |
186 | KCSAN_CHECK_WRITE_BARRIER(atomic_add_return_release(1, &dummy)); |
187 | KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add(1, &dummy)); |
188 | KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy)); |
189 | KCSAN_CHECK_WRITE_BARRIER(test_and_set_bit(0, &test_var)); |
190 | KCSAN_CHECK_WRITE_BARRIER(test_and_clear_bit(0, &test_var)); |
191 | KCSAN_CHECK_WRITE_BARRIER(test_and_change_bit(0, &test_var)); |
192 | KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock(0, &test_var)); |
193 | KCSAN_CHECK_WRITE_BARRIER(__clear_bit_unlock(0, &test_var)); |
194 | arch_spin_lock(&arch_spinlock); |
195 | KCSAN_CHECK_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock)); |
196 | spin_lock(lock: &test_spinlock); |
197 | KCSAN_CHECK_WRITE_BARRIER(spin_unlock(&test_spinlock)); |
198 | |
199 | KCSAN_CHECK_RW_BARRIER(mb()); |
200 | KCSAN_CHECK_RW_BARRIER(wmb()); |
201 | KCSAN_CHECK_RW_BARRIER(rmb()); |
202 | KCSAN_CHECK_RW_BARRIER(smp_mb()); |
203 | KCSAN_CHECK_RW_BARRIER(smp_wmb()); |
204 | KCSAN_CHECK_RW_BARRIER(smp_rmb()); |
205 | KCSAN_CHECK_RW_BARRIER(dma_wmb()); |
206 | KCSAN_CHECK_RW_BARRIER(dma_rmb()); |
207 | KCSAN_CHECK_RW_BARRIER(smp_mb__before_atomic()); |
208 | KCSAN_CHECK_RW_BARRIER(smp_mb__after_atomic()); |
209 | KCSAN_CHECK_RW_BARRIER(smp_mb__after_spinlock()); |
210 | KCSAN_CHECK_RW_BARRIER(smp_store_mb(test_var, 0)); |
211 | KCSAN_CHECK_RW_BARRIER(smp_store_release(&test_var, 0)); |
212 | KCSAN_CHECK_RW_BARRIER(xchg(&test_var, 0)); |
213 | KCSAN_CHECK_RW_BARRIER(xchg_release(&test_var, 0)); |
214 | KCSAN_CHECK_RW_BARRIER(cmpxchg(&test_var, 0, 0)); |
215 | KCSAN_CHECK_RW_BARRIER(cmpxchg_release(&test_var, 0, 0)); |
216 | KCSAN_CHECK_RW_BARRIER(atomic_set_release(&dummy, 0)); |
217 | KCSAN_CHECK_RW_BARRIER(atomic_add_return(1, &dummy)); |
218 | KCSAN_CHECK_RW_BARRIER(atomic_add_return_release(1, &dummy)); |
219 | KCSAN_CHECK_RW_BARRIER(atomic_fetch_add(1, &dummy)); |
220 | KCSAN_CHECK_RW_BARRIER(atomic_fetch_add_release(1, &dummy)); |
221 | KCSAN_CHECK_RW_BARRIER(test_and_set_bit(0, &test_var)); |
222 | KCSAN_CHECK_RW_BARRIER(test_and_clear_bit(0, &test_var)); |
223 | KCSAN_CHECK_RW_BARRIER(test_and_change_bit(0, &test_var)); |
224 | KCSAN_CHECK_RW_BARRIER(clear_bit_unlock(0, &test_var)); |
225 | KCSAN_CHECK_RW_BARRIER(__clear_bit_unlock(0, &test_var)); |
226 | arch_spin_lock(&arch_spinlock); |
227 | KCSAN_CHECK_RW_BARRIER(arch_spin_unlock(&arch_spinlock)); |
228 | spin_lock(lock: &test_spinlock); |
229 | KCSAN_CHECK_RW_BARRIER(spin_unlock(&test_spinlock)); |
230 | KCSAN_CHECK_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); |
231 | KCSAN_CHECK_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); |
232 | KCSAN_CHECK_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); |
233 | kcsan_nestable_atomic_end(); |
234 | |
235 | return ret; |
236 | } |
237 | |
238 | static int __init kcsan_selftest(void) |
239 | { |
240 | int passed = 0; |
241 | int total = 0; |
242 | |
243 | #define RUN_TEST(do_test) \ |
244 | do { \ |
245 | ++total; \ |
246 | if (do_test()) \ |
247 | ++passed; \ |
248 | else \ |
249 | pr_err("selftest: " #do_test " failed"); \ |
250 | } while (0) |
251 | |
252 | RUN_TEST(test_encode_decode); |
253 | RUN_TEST(test_matching_access); |
254 | RUN_TEST(test_barrier); |
255 | |
256 | pr_info("selftest: %d/%d tests passed\n" , passed, total); |
257 | if (passed != total) |
258 | panic(fmt: "selftests failed" ); |
259 | return 0; |
260 | } |
261 | postcore_initcall(kcsan_selftest); |
262 | |