diff options
| -rw-r--r-- | kernel/kcsan/debugfs.c | 51 |
1 files changed, 46 insertions, 5 deletions
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c index a9dad44130e6..9bbba0e57c9b 100644 --- a/kernel/kcsan/debugfs.c +++ b/kernel/kcsan/debugfs.c @@ -6,6 +6,7 @@ #include <linux/debugfs.h> #include <linux/init.h> #include <linux/kallsyms.h> +#include <linux/sched.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/sort.h> @@ -69,9 +70,9 @@ void kcsan_counter_dec(enum kcsan_counter_id id) /* * The microbenchmark allows benchmarking KCSAN core runtime only. To run * multiple threads, pipe 'microbench=<iters>' from multiple tasks into the - * debugfs file. + * debugfs file. This will not generate any conflicts, and tests fast-path only. */ -static void microbenchmark(unsigned long iters) +static noinline void microbenchmark(unsigned long iters) { cycles_t cycles; @@ -81,18 +82,52 @@ static void microbenchmark(unsigned long iters) while (iters--) { /* * We can run this benchmark from multiple tasks; this address - * calculation increases likelyhood of some accesses overlapping - * (they still won't conflict because all are reads). + * calculation increases likelyhood of some accesses + * overlapping. Make the access type an atomic read, to never + * set up watchpoints and test the fast-path only. */ unsigned long addr = iters % (CONFIG_KCSAN_NUM_WATCHPOINTS * PAGE_SIZE); - __kcsan_check_read((void *)addr, sizeof(long)); + __kcsan_check_access((void *)addr, sizeof(long), KCSAN_ACCESS_ATOMIC); } cycles = get_cycles() - cycles; pr_info("KCSAN: %s end | cycles: %llu\n", __func__, cycles); } +/* + * Simple test to create conflicting accesses. Write 'test=<iters>' to KCSAN's + * debugfs file from multiple tasks to generate real conflicts and show reports. + */ +static long test_dummy; +static noinline void test_thread(unsigned long iters) +{ + const struct kcsan_ctx ctx_save = current->kcsan_ctx; + cycles_t cycles; + + /* We may have been called from an atomic region; reset context. */ + memset(¤t->kcsan_ctx, 0, sizeof(current->kcsan_ctx)); + + pr_info("KCSAN: %s begin | iters: %lu\n", __func__, iters); + + cycles = get_cycles(); + while (iters--) { + __kcsan_check_read(&test_dummy, sizeof(test_dummy)); + __kcsan_check_write(&test_dummy, sizeof(test_dummy)); + ASSERT_EXCLUSIVE_WRITER(test_dummy); + ASSERT_EXCLUSIVE_ACCESS(test_dummy); + + /* not actually instrumented */ + WRITE_ONCE(test_dummy, iters); /* to observe value-change */ + } + cycles = get_cycles() - cycles; + + pr_info("KCSAN: %s end | cycles: %llu\n", __func__, cycles); + + /* restore context */ + current->kcsan_ctx = ctx_save; +} + static int cmp_filterlist_addrs(const void *rhs, const void *lhs) { const unsigned long a = *(const unsigned long *)rhs; @@ -242,6 +277,12 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o if (kstrtoul(&arg[sizeof("microbench=") - 1], 0, &iters)) return -EINVAL; microbenchmark(iters); + } else if (!strncmp(arg, "test=", sizeof("test=") - 1)) { + unsigned long iters; + + if (kstrtoul(&arg[sizeof("test=") - 1], 0, &iters)) + return -EINVAL; + test_thread(iters); } else if (!strcmp(arg, "whitelist")) { set_report_filterlist_whitelist(true); } else if (!strcmp(arg, "blacklist")) { |