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 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 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);
40 prandom_bytes(&addr, sizeof(addr));
44 if (WARN_ON(!check_encodable(addr, size)))
47 /* Encode and decode */
49 const long encoded_watchpoint =
50 encode_watchpoint(addr, size, is_write);
51 unsigned long verif_masked_addr;
55 /* Check special watchpoints */
56 if (WARN_ON(decode_watchpoint(
57 INVALID_WATCHPOINT, &verif_masked_addr,
58 &verif_size, &verif_is_write)))
60 if (WARN_ON(decode_watchpoint(
61 CONSUMED_WATCHPOINT, &verif_masked_addr,
62 &verif_size, &verif_is_write)))
65 /* Check decoding watchpoint returns same data */
66 if (WARN_ON(!decode_watchpoint(
67 encoded_watchpoint, &verif_masked_addr,
68 &verif_size, &verif_is_write)))
70 if (WARN_ON(verif_masked_addr !=
71 (addr & WATCHPOINT_ADDR_MASK)))
73 if (WARN_ON(verif_size != size))
75 if (WARN_ON(is_write != verif_is_write))
80 pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
81 __func__, is_write ? "write" : "read", size,
82 addr, encoded_watchpoint,
83 verif_is_write ? "write" : "read", verif_size,
92 /* Test access matching function. */
93 static bool test_matching_access(void)
95 if (WARN_ON(!matching_access(10, 1, 10, 1)))
97 if (WARN_ON(!matching_access(10, 2, 11, 1)))
99 if (WARN_ON(!matching_access(10, 1, 9, 2)))
101 if (WARN_ON(matching_access(10, 1, 11, 1)))
103 if (WARN_ON(matching_access(9, 1, 10, 1)))
107 * An access of size 0 could match another access, as demonstrated here.
108 * Rather than add more comparisons to 'matching_access()', which would
109 * end up in the fast-path for *all* checks, check_access() simply
110 * returns for all accesses of size 0.
112 if (WARN_ON(!matching_access(8, 8, 12, 0)))
118 static int __init kcsan_selftest(void)
123 #define RUN_TEST(do_test) \
129 pr_err("selftest: " #do_test " failed"); \
132 RUN_TEST(test_requires);
133 RUN_TEST(test_encode_decode);
134 RUN_TEST(test_matching_access);
136 pr_info("selftest: %d/%d tests passed\n", passed, total);
138 panic("selftests failed");
141 postcore_initcall(kcsan_selftest);