These tests share a common structure and are grouped together. - buggy(): exposes the stack address to corrupting(); may omit waiting - corrupting(): reads the exposed pointer and modifies memory; if buggy() omits waiting, victim()'s buffer is corrupted - victim(): initializes a local buffer and later verifies it; reports an error if the buffer was unexpectedly modified
buggy() and victim() run in worker() thread, with similar stack frame sizes to simplify testing. By adjusting fence_size in corrupting(), the test can trigger either silent corruption or overflow across threads. - Test 3: one worker, 20 loops, silent corruption - Test 4: 20 workers, one loop each, silent corruption - Test 5: one worker, one loop, overflow corruption Test 4 also exercises multiple watchpoint instances. Signed-off-by: Jinchao Wang <[email protected]> mm/ksw: add KSTACKWATCH_PROFILING to measure probe cost Introduce CONFIG_KSTACKWATCH_PROFILING to enable optional runtime profiling in KStackWatch. When enabled, it records entry and exit probe latencies (in nanoseconds and CPU cycles) and reports averaged statistics at module exit. Signed-off-by: Jinchao Wang <[email protected]> --- mm/kstackwatch/test.c | 186 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 185 insertions(+), 1 deletion(-) diff --git a/mm/kstackwatch/test.c b/mm/kstackwatch/test.c index 1d196f72faba..4bd0e5026fd9 100644 --- a/mm/kstackwatch/test.c +++ b/mm/kstackwatch/test.c @@ -19,6 +19,20 @@ static struct dentry *test_file; #define BUFFER_SIZE 32 #define MAX_DEPTH 6 +struct work_node { + ulong *ptr; + u64 start_ns; + struct completion done; + struct list_head list; +}; + +static DECLARE_COMPLETION(work_res); +static DEFINE_MUTEX(work_mutex); +static LIST_HEAD(work_list); + +static int global_fence_size; +static int global_loop_count; + static void test_watch_fire(void) { u64 buffer[BUFFER_SIZE] = { 0 }; @@ -64,6 +78,164 @@ static void test_recursive_depth(int depth) pr_info("exit of %s depth:%d\n", __func__, depth); } +static struct work_node *test_mthread_buggy(int thread_id, int seq_id) +{ + ulong buf[BUFFER_SIZE]; + struct work_node *node; + bool trigger; + + node = kmalloc(sizeof(*node), GFP_KERNEL); + if (!node) + return NULL; + + init_completion(&node->done); + node->ptr = buf; + node->start_ns = ktime_get_ns(); + mutex_lock(&work_mutex); + list_add(&node->list, &work_list); + mutex_unlock(&work_mutex); + complete(&work_res); + + trigger = (get_random_u32() % 100) < 10; + if (trigger) + return node; /* let the caller handle cleanup */ + + wait_for_completion(&node->done); + kfree(node); + return NULL; +} + +#define CORRUPTING_MINIOR_WAIT_NS (100000) +#define VICTIM_MINIOR_WAIT_NS (300000) + +static inline void silent_wait_us(u64 start_ns, u64 min_wait_us) +{ + u64 diff_ns, remain_us; + + diff_ns = ktime_get_ns() - start_ns; + if (diff_ns < min_wait_us * 1000ULL) { + remain_us = min_wait_us - (diff_ns >> 10); + usleep_range(remain_us, remain_us + 200); + } +} + +static void test_mthread_victim(int thread_id, int seq_id, u64 start_ns) +{ + ulong buf[BUFFER_SIZE]; + + for (int j = 0; j < BUFFER_SIZE; j++) + buf[j] = 0xdeadbeef + seq_id; + if (start_ns) + silent_wait_us(start_ns, VICTIM_MINIOR_WAIT_NS); + + for (int j = 0; j < BUFFER_SIZE; j++) { + if (buf[j] != (0xdeadbeef + seq_id)) { + pr_warn("victim[%d][%d]: unhappy buf[%d]=0x%lx\n", + thread_id, seq_id, j, buf[j]); + return; + } + } + + pr_info("victim[%d][%d]: happy\n", thread_id, seq_id); +} + +static int test_mthread_corrupting(void *data) +{ + struct work_node *node; + int fence_size; + + while (!kthread_should_stop()) { + if (!wait_for_completion_timeout(&work_res, HZ)) + continue; + while (true) { + mutex_lock(&work_mutex); + node = list_first_entry_or_null(&work_list, + struct work_node, list); + if (node) + list_del(&node->list); + mutex_unlock(&work_mutex); + + if (!node) + break; /* no more nodes, exit inner loop */ + silent_wait_us(node->start_ns, + CORRUPTING_MINIOR_WAIT_NS); + + fence_size = READ_ONCE(global_fence_size); + for (int i = fence_size; i < BUFFER_SIZE - fence_size; + i++) + node->ptr[i] = 0xabcdabcd; + + complete(&node->done); + } + } + + return 0; +} + +static int test_mthread_worker(void *data) +{ + int thread_id = (long)data; + int loop_count; + struct work_node *node; + + loop_count = READ_ONCE(global_loop_count); + + for (int i = 0; i < loop_count; i++) { + node = test_mthread_buggy(thread_id, i); + + if (node) + test_mthread_victim(thread_id, i, node->start_ns); + else + test_mthread_victim(thread_id, i, 0); + if (node) { + wait_for_completion(&node->done); + kfree(node); + } + } + return 0; +} + +static void test_mthread_case(int num_workers, int loop_count, int fence_size) +{ + static struct task_struct *corrupting; + static struct task_struct **workers; + + WRITE_ONCE(global_loop_count, loop_count); + WRITE_ONCE(global_fence_size, fence_size); + + init_completion(&work_res); + workers = kmalloc_array(num_workers, sizeof(void *), GFP_KERNEL); + memset(workers, 0, sizeof(struct task_struct *) * num_workers); + + corrupting = kthread_run(test_mthread_corrupting, NULL, "corrupting"); + if (IS_ERR(corrupting)) { + pr_err("failed to create corrupting thread\n"); + return; + } + + for (ulong i = 0; i < num_workers; i++) { + workers[i] = kthread_run(test_mthread_worker, (void *)i, + "worker_%ld", i); + if (IS_ERR(workers[i])) { + pr_err("failto create worker thread %ld", i); + workers[i] = NULL; + } + } + + for (ulong i = 0; i < num_workers; i++) { + if (workers[i] && workers[i]->__state != TASK_DEAD) { + usleep_range(1000, 2000); + i--; + } + } + kfree(workers); + + if (corrupting && !IS_ERR(corrupting)) { + kthread_stop(corrupting); + corrupting = NULL; + } +} + static ssize_t test_dbgfs_write(struct file *file, const char __user *buffer, size_t count, loff_t *pos) { @@ -92,6 +264,15 @@ static ssize_t test_dbgfs_write(struct file *file, const char __user *buffer, case 2: test_recursive_depth(0); break; + case 3: + test_mthread_case(1, 20, BUFFER_SIZE / 4); + break; + case 4: + test_mthread_case(200, 1, BUFFER_SIZE / 4); + break; + case 5: + test_mthread_case(1, 1, -3); + break; default: pr_err("Unknown test number %d\n", test_num); return -EINVAL; @@ -114,7 +295,10 @@ static ssize_t test_dbgfs_read(struct file *file, char __user *buffer, "echo test{i} > /sys/kernel/debug/kstackwatch/test\n" " test0 - test watch fire\n" " test1 - test canary overflow\n" - " test2 - test recursive func\n"; + " test2 - test recursive func\n" + " test3 - test silent corruption\n" + " test4 - test multiple silent corruption\n" + " test5 - test prologue corruption\n"; return simple_read_from_buffer(buffer, count, ppos, usage, strlen(usage)); -- 2.43.0
