1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/init.h> 4 #include <linux/kernel.h> 5 #include <linux/printk.h> 6 #include <linux/random.h> 7 #include <linux/types.h> 8 9 #include "encoding.h" 10 11 #define ITERS_PER_TEST 2000 12 13 /* Test requirements. */ 14 static bool test_requires(void) 15 { 16 /* random should be initialized for the below tests */ 17 return prandom_u32() + prandom_u32() != 0; 18 } 19 20 /* 21 * Test watchpoint encode and decode: check that encoding some access's info, 22 * and then subsequent decode preserves the access's info. 23 */ 24 static bool test_encode_decode(void) 25 { 26 int i; 27 28 for (i = 0; i < ITERS_PER_TEST; ++i) { 29 size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1; 30 bool is_write = !!prandom_u32_max(2); 31 unsigned long addr; 32 33 prandom_bytes(&addr, sizeof(addr)); 34 if (WARN_ON(!check_encodable(addr, size))) 35 return false; 36 37 /* Encode and decode */ 38 { 39 const long encoded_watchpoint = 40 encode_watchpoint(addr, size, is_write); 41 unsigned long verif_masked_addr; 42 size_t verif_size; 43 bool verif_is_write; 44 45 /* Check special watchpoints */ 46 if (WARN_ON(decode_watchpoint( 47 INVALID_WATCHPOINT, &verif_masked_addr, 48 &verif_size, &verif_is_write))) 49 return false; 50 if (WARN_ON(decode_watchpoint( 51 CONSUMED_WATCHPOINT, &verif_masked_addr, 52 &verif_size, &verif_is_write))) 53 return false; 54 55 /* Check decoding watchpoint returns same data */ 56 if (WARN_ON(!decode_watchpoint( 57 encoded_watchpoint, &verif_masked_addr, 58 &verif_size, &verif_is_write))) 59 return false; 60 if (WARN_ON(verif_masked_addr != 61 (addr & WATCHPOINT_ADDR_MASK))) 62 goto fail; 63 if (WARN_ON(verif_size != size)) 64 goto fail; 65 if (WARN_ON(is_write != verif_is_write)) 66 goto fail; 67 68 continue; 69 fail: 70 pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n", 71 __func__, is_write ? "write" : "read", size, 72 addr, encoded_watchpoint, 73 verif_is_write ? "write" : "read", verif_size, 74 verif_masked_addr); 75 return false; 76 } 77 } 78 79 return true; 80 } 81 82 /* Test access matching function. */ 83 static bool test_matching_access(void) 84 { 85 if (WARN_ON(!matching_access(10, 1, 10, 1))) 86 return false; 87 if (WARN_ON(!matching_access(10, 2, 11, 1))) 88 return false; 89 if (WARN_ON(!matching_access(10, 1, 9, 2))) 90 return false; 91 if (WARN_ON(matching_access(10, 1, 11, 1))) 92 return false; 93 if (WARN_ON(matching_access(9, 1, 10, 1))) 94 return false; 95 96 /* 97 * An access of size 0 could match another access, as demonstrated here. 98 * Rather than add more comparisons to 'matching_access()', which would 99 * end up in the fast-path for *all* checks, check_access() simply 100 * returns for all accesses of size 0. 101 */ 102 if (WARN_ON(!matching_access(8, 8, 12, 0))) 103 return false; 104 105 return true; 106 } 107 108 static int __init kcsan_selftest(void) 109 { 110 int passed = 0; 111 int total = 0; 112 113 #define RUN_TEST(do_test) \ 114 do { \ 115 ++total; \ 116 if (do_test()) \ 117 ++passed; \ 118 else \ 119 pr_err("KCSAN selftest: " #do_test " failed"); \ 120 } while (0) 121 122 RUN_TEST(test_requires); 123 RUN_TEST(test_encode_decode); 124 RUN_TEST(test_matching_access); 125 126 pr_info("KCSAN selftest: %d/%d tests passed\n", passed, total); 127 if (passed != total) 128 panic("KCSAN selftests failed"); 129 return 0; 130 } 131 postcore_initcall(kcsan_selftest); 132