Add a standalone test module for KStackWatch to validate functionality in controlled scenarios.
The module exposes a simple interface via debugfs (/sys/kernel/debug/kstackwatch/test), allowing specific test cases to be triggered with commands such as: echo test0 > /sys/kernel/debug/kstackwatch/test To ensure predictable behavior during testing, the module is built with optimizations disabled. Signed-off-by: Jinchao Wang <[email protected]> show addr of buf and watch_addr of test case --- include/linux/kstackwatch.h | 2 + mm/kstackwatch/Kconfig | 10 +++ mm/kstackwatch/Makefile | 6 ++ mm/kstackwatch/kernel.c | 5 ++ mm/kstackwatch/test.c | 121 ++++++++++++++++++++++++++++++++++++ 5 files changed, 144 insertions(+) create mode 100644 mm/kstackwatch/test.c diff --git a/include/linux/kstackwatch.h b/include/linux/kstackwatch.h index 6daded932ba6..7711efe85240 100644 --- a/include/linux/kstackwatch.h +++ b/include/linux/kstackwatch.h @@ -40,6 +40,8 @@ struct ksw_config { // singleton, only modified in kernel.c const struct ksw_config *ksw_get_config(void); +struct dentry *ksw_get_dbgdir(void); + /* stack management */ int ksw_stack_init(void); diff --git a/mm/kstackwatch/Kconfig b/mm/kstackwatch/Kconfig index 3c9385a15c33..343b492ddbd3 100644 --- a/mm/kstackwatch/Kconfig +++ b/mm/kstackwatch/Kconfig @@ -22,3 +22,13 @@ config KSTACKWATCH_PROFILING stopping. Useful for performance tuning, not for production use. If unsure, say N. + +config KSTACKWATCH_TEST + tristate "KStackWatch Test Module" + depends on KSTACKWATCH + help + This module provides controlled stack corruption scenarios to verify + the functionality of KStackWatch. It is useful for development and + validation of KStackWatch mechanism. + + If unsure, say N. diff --git a/mm/kstackwatch/Makefile b/mm/kstackwatch/Makefile index c99c621eac02..a2c7cd647f69 100644 --- a/mm/kstackwatch/Makefile +++ b/mm/kstackwatch/Makefile @@ -1,2 +1,8 @@ obj-$(CONFIG_KSTACKWATCH) += kstackwatch.o kstackwatch-y := kernel.o stack.o watch.o + +obj-$(CONFIG_KSTACKWATCH_TEST) += kstackwatch_test.o +kstackwatch_test-y := test.o +CFLAGS_test.o := -fno-inline \ + -fno-optimize-sibling-calls \ + -fno-pic -fno-pie -O0 -Og diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index a0e676e60692..b25cf6830b15 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -235,6 +235,11 @@ const struct ksw_config *ksw_get_config(void) return ksw_config; } +struct dentry *ksw_get_dbgdir(void) +{ + return dbgfs_dir; +} + static int __init kstackwatch_init(void) { int ret = 0; diff --git a/mm/kstackwatch/test.c b/mm/kstackwatch/test.c new file mode 100644 index 000000000000..2969564b1a00 --- /dev/null +++ b/mm/kstackwatch/test.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/debugfs.h> +#include <linux/delay.h> +#include <linux/kthread.h> +#include <linux/kstackwatch.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/prandom.h> +#include <linux/printk.h> +#include <linux/random.h> +#include <linux/spinlock.h> +#include <linux/string.h> +#include <linux/uaccess.h> + +static struct dentry *test_file; + +#define BUFFER_SIZE 32 + +static void test_watch_fire(void) +{ + u64 buffer[BUFFER_SIZE] = { 0 }; + + pr_info("entry of %s\n", __func__); + ksw_watch_show(); + pr_info("buf: 0x%px\n", buffer); + + ksw_watch_fire(); + + barrier_data(buffer); + pr_info("exit of %s\n", __func__); +} + +static ssize_t test_dbgfs_write(struct file *file, const char __user *buffer, + size_t count, loff_t *pos) +{ + char cmd[256]; + int test_num; + + if (count >= sizeof(cmd)) + return -EINVAL; + + if (copy_from_user(cmd, buffer, count)) + return -EFAULT; + + cmd[count] = '\0'; + strim(cmd); + + pr_info("received command: %s\n", cmd); + + if (sscanf(cmd, "test%d", &test_num) == 1) { + switch (test_num) { + case 0: + test_watch_fire(); + break; + default: + pr_err("Unknown test number %d\n", test_num); + return -EINVAL; + } + } else { + pr_err("invalid command format. Use 'testN'.\n"); + return -EINVAL; + } + + return count; +} + +static ssize_t test_dbgfs_read(struct file *file, char __user *buffer, + size_t count, loff_t *ppos) +{ + static const char usage[] = + "KStackWatch Simplified Test Module\n" + "============ usage ===============\n" + "Usage:\n" + "echo test{i} > /sys/kernel/debug/kstackwatch/test\n" + " test0 - test watch fire\n"; + + return simple_read_from_buffer(buffer, count, ppos, usage, + strlen(usage)); +} + +static const struct file_operations test_dbgfs_fops = { + .owner = THIS_MODULE, + .read = test_dbgfs_read, + .write = test_dbgfs_write, + .llseek = noop_llseek, +}; + +static int __init kstackwatch_test_init(void) +{ + struct dentry *ksw_dir = ksw_get_dbgdir(); + + if (!ksw_dir) { + pr_err("kstackwatch must be loaded first\n"); + return -ENODEV; + } + + test_file = debugfs_create_file("test", 0600, ksw_dir, NULL, + &test_dbgfs_fops); + if (!test_file) { + pr_err("Failed to create debugfs test file\n"); + return -ENOMEM; + } + + pr_info("module loaded\n"); + return 0; +} + +static void __exit kstackwatch_test_exit(void) +{ + debugfs_remove(test_file); + pr_info("module unloaded\n"); +} + +module_init(kstackwatch_test_init); +module_exit(kstackwatch_test_exit); + +MODULE_AUTHOR("Jinchao Wang"); +MODULE_DESCRIPTION("KStackWatch Test Module"); +MODULE_LICENSE("GPL"); -- 2.43.0
