1 // SPDX-License-Identifier: GPL-2.0
3 * KCSAN short boot-time selftests.
5 * Copyright (C) 2019, Google LLC.
8 #define pr_fmt(fmt) "kcsan: " fmt
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <linux/printk.h>
13 #include <linux/random.h>
14 #include <linux/types.h>
18 #define ITERS_PER_TEST 2000
20 /* Test requirements. */
21 static bool __init test_requires(void)
23 /* random should be initialized for the below tests */
24 return prandom_u32() + prandom_u32() != 0;
28 * Test watchpoint encode and decode: check that encoding some access's info,
29 * and then subsequent decode preserves the access's info.
31 static bool __init test_encode_decode(void)
35 for (i = 0; i < ITERS_PER_TEST; ++i) {
36 size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1;
37 bool is_write = !!prandom_u32_max(2);
38 unsigned long verif_masked_addr;
39 long encoded_watchpoint;
44 prandom_bytes(&addr, sizeof(addr));
48 if (WARN_ON(!check_encodable(addr, size)))
51 encoded_watchpoint = encode_watchpoint(addr, size, is_write);
53 /* Check special watchpoints */
54 if (WARN_ON(decode_watchpoint(INVALID_WATCHPOINT, &verif_masked_addr, &verif_size, &verif_is_write)))
56 if (WARN_ON(decode_watchpoint(CONSUMED_WATCHPOINT, &verif_masked_addr, &verif_size, &verif_is_write)))
59 /* Check decoding watchpoint returns same data */
60 if (WARN_ON(!decode_watchpoint(encoded_watchpoint, &verif_masked_addr, &verif_size, &verif_is_write)))
62 if (WARN_ON(verif_masked_addr != (addr & WATCHPOINT_ADDR_MASK)))
64 if (WARN_ON(verif_size != size))
66 if (WARN_ON(is_write != verif_is_write))
71 pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
72 __func__, is_write ? "write" : "read", size, addr, encoded_watchpoint,
73 verif_is_write ? "write" : "read", verif_size, verif_masked_addr);
80 /* Test access matching function. */
81 static bool __init test_matching_access(void)
83 if (WARN_ON(!matching_access(10, 1, 10, 1)))
85 if (WARN_ON(!matching_access(10, 2, 11, 1)))
87 if (WARN_ON(!matching_access(10, 1, 9, 2)))
89 if (WARN_ON(matching_access(10, 1, 11, 1)))
91 if (WARN_ON(matching_access(9, 1, 10, 1)))
95 * An access of size 0 could match another access, as demonstrated here.
96 * Rather than add more comparisons to 'matching_access()', which would
97 * end up in the fast-path for *all* checks, check_access() simply
98 * returns for all accesses of size 0.
100 if (WARN_ON(!matching_access(8, 8, 12, 0)))
106 static int __init kcsan_selftest(void)
111 #define RUN_TEST(do_test) \
117 pr_err("selftest: " #do_test " failed"); \
120 RUN_TEST(test_requires);
121 RUN_TEST(test_encode_decode);
122 RUN_TEST(test_matching_access);
124 pr_info("selftest: %d/%d tests passed\n", passed, total);
126 panic("selftests failed");
129 postcore_initcall(kcsan_selftest);