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- // SPDX-License-Identifier: GPL-2.0
- #define pr_fmt(fmt) "kcsan: " fmt
- #include <linux/init.h>
- #include <linux/kernel.h>
- #include <linux/printk.h>
- #include <linux/random.h>
- #include <linux/types.h>
- #include "encoding.h"
- #define ITERS_PER_TEST 2000
- /* Test requirements. */
- static bool test_requires(void)
- {
- /* random should be initialized for the below tests */
- return prandom_u32() + prandom_u32() != 0;
- }
- /*
- * Test watchpoint encode and decode: check that encoding some access's info,
- * and then subsequent decode preserves the access's info.
- */
- static bool test_encode_decode(void)
- {
- int i;
- for (i = 0; i < ITERS_PER_TEST; ++i) {
- size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1;
- bool is_write = !!prandom_u32_max(2);
- unsigned long addr;
- prandom_bytes(&addr, sizeof(addr));
- if (WARN_ON(!check_encodable(addr, size)))
- return false;
- /* Encode and decode */
- {
- const long encoded_watchpoint =
- encode_watchpoint(addr, size, is_write);
- unsigned long verif_masked_addr;
- size_t verif_size;
- bool verif_is_write;
- /* Check special watchpoints */
- if (WARN_ON(decode_watchpoint(
- INVALID_WATCHPOINT, &verif_masked_addr,
- &verif_size, &verif_is_write)))
- return false;
- if (WARN_ON(decode_watchpoint(
- CONSUMED_WATCHPOINT, &verif_masked_addr,
- &verif_size, &verif_is_write)))
- return false;
- /* Check decoding watchpoint returns same data */
- if (WARN_ON(!decode_watchpoint(
- encoded_watchpoint, &verif_masked_addr,
- &verif_size, &verif_is_write)))
- return false;
- if (WARN_ON(verif_masked_addr !=
- (addr & WATCHPOINT_ADDR_MASK)))
- goto fail;
- if (WARN_ON(verif_size != size))
- goto fail;
- if (WARN_ON(is_write != verif_is_write))
- goto fail;
- continue;
- fail:
- pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
- __func__, is_write ? "write" : "read", size,
- addr, encoded_watchpoint,
- verif_is_write ? "write" : "read", verif_size,
- verif_masked_addr);
- return false;
- }
- }
- return true;
- }
- /* Test access matching function. */
- static bool test_matching_access(void)
- {
- if (WARN_ON(!matching_access(10, 1, 10, 1)))
- return false;
- if (WARN_ON(!matching_access(10, 2, 11, 1)))
- return false;
- if (WARN_ON(!matching_access(10, 1, 9, 2)))
- return false;
- if (WARN_ON(matching_access(10, 1, 11, 1)))
- return false;
- if (WARN_ON(matching_access(9, 1, 10, 1)))
- return false;
- /*
- * An access of size 0 could match another access, as demonstrated here.
- * Rather than add more comparisons to 'matching_access()', which would
- * end up in the fast-path for *all* checks, check_access() simply
- * returns for all accesses of size 0.
- */
- if (WARN_ON(!matching_access(8, 8, 12, 0)))
- return false;
- return true;
- }
- static int __init kcsan_selftest(void)
- {
- int passed = 0;
- int total = 0;
- #define RUN_TEST(do_test) \
- do { \
- ++total; \
- if (do_test()) \
- ++passed; \
- else \
- pr_err("selftest: " #do_test " failed"); \
- } while (0)
- RUN_TEST(test_requires);
- RUN_TEST(test_encode_decode);
- RUN_TEST(test_matching_access);
- pr_info("selftest: %d/%d tests passed\n", passed, total);
- if (passed != total)
- panic("selftests failed");
- return 0;
- }
- postcore_initcall(kcsan_selftest);
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