Reorganize the source codeHEADmaster

6 files changed, 1241 insertions, 0 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
new file mode 100644
index 0000000..71abe65
--- /dev/null
+++ b/kernel/Makefile
@@ -0,0 +1,3 @@
+# KMOD = variable_monitor
+# obj-m := kernel/$(KMOD).o
+# $(KMOD)-objs := kernel/monitor_kernel.o
diff --git a/kernel/monitor_kernel.c b/kernel/monitor_kernel.c
new file mode 100644
index 0000000..1d17d64
--- /dev/null
+++ b/kernel/monitor_kernel.c
@@ -0,0 +1,157 @@
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include "monitor_kernel_lib.c"
+#include "monitor_kernel_task.c"
+
+#define DEVICE_NAME "variable_monitor"
+
+// for character device
+static dev_t dev_num;
+static struct cdev *watch_cdev;
+static struct class *watch_class;
+
+struct my_device_data {
+  pid_t pid;
+};
+
+static int device_open(struct inode *inode, struct file *file) {
+  struct my_device_data *data;
+  printk(KERN_INFO "%s: with pid %d\n", __FUNCTION__, current->pid);
+  // save pid
+  data = kmalloc(sizeof(*data), GFP_KERNEL);
+  if (!data)
+    return -ENOMEM;
+  data->pid = current->pid;
+  file->private_data = data;
+  return 0;
+}
+
+static int device_release(struct inode *inode, struct file *file) {
+  // printk(KERN_INFO "%s\n", __FUNCTION__);
+  // load pid
+  struct my_device_data *data = file->private_data;
+  // clear watch with pid
+  clear_watch(data->pid);
+  kfree(data); // free data memory
+  return 0;
+}
+
+static long device_ioctl(struct file *file, unsigned int ioctl_num,
+                         unsigned long ioctl_param) {
+  watch_arg warg;
+  void *kptr;
+  kernel_watch_timer *timer = NULL;
+  kernel_watch_arg k_watch_arg;
+  // copy watch_arg
+  if (copy_from_user(&warg, (watch_arg *)ioctl_param, sizeof(warg))) {
+    return -EACCES;
+  }
+
+  printk(KERN_INFO "Watch_arg: task_id=%d, name=%s, ptr=%p, length_byte=%d, "
+                   "time_ns=%ld, threshold=%lld\n",
+         warg.task_id, warg.name, warg.ptr, warg.length_byte, warg.time_ns,
+         warg.threshold);
+  // user space address to kernel space address
+  kptr = convert_user_space_ptr(warg.task_id, (unsigned long)warg.ptr);
+  if (kptr == NULL) {
+    printk(KERN_ERR "Cannot access user space\n");
+    return -EACCES;
+  }
+  // check length
+  if (warg.length_byte != 1 && warg.length_byte != 2 && warg.length_byte != 4 &&
+      warg.length_byte != 8) {
+    printk(KERN_ERR "Invalid length %d\n", warg.length_byte);
+    return -EINVAL;
+  }
+  // k_watch_arg init
+  w_arg2k_w_arg(kptr, warg, &k_watch_arg);
+  timer = get_timer(warg.time_ns); // get a valuable timer
+
+  printk(KERN_INFO "ptr transform kptr: %p\n", kptr);
+  printk(KERN_INFO "timer: %p\n", timer);
+  printk(KERN_INFO "timer->sentinel: %d, timer->time_ns: %lld\n",
+         timer->sentinel, timer->time_ns);
+  printk(KERN_INFO "timer->hr_timer: %p\n", &timer->hr_timer);
+
+  TIMER_CANCEL(timer); // just in case
+  timer_add_watch(timer, k_watch_arg);
+  TIMER_START(timer);
+
+  printk(KERN_INFO "Start watching var: %s\n", warg.name);
+  return 0;
+}
+
+static struct file_operations fops = {
+    .open = device_open,
+    .release = device_release,
+    .unlocked_ioctl = device_ioctl,
+};
+
+int init_module(void) {
+  printk(KERN_INFO "%s\n", __FUNCTION__);
+  if (alloc_chrdev_region(&dev_num, 0, 1, DEVICE_NAME) < 0) {
+    printk(KERN_ALERT "Failed to register device number\n");
+    return -1;
+  }
+
+  if ((watch_cdev = cdev_alloc()) == NULL) {
+    printk(KERN_ALERT "Failed to allocate cdev structure\n");
+    unregister_chrdev_region(dev_num, 1);
+    return -1;
+  }
+
+  cdev_init(watch_cdev, &fops);
+  if (cdev_add(watch_cdev, dev_num, 1) == -1) {
+    printk(KERN_ALERT "Failed to add cdev structure\n");
+    device_destroy(watch_class, dev_num);
+    class_destroy(watch_class);
+    unregister_chrdev_region(dev_num, 1);
+    return -1;
+  }
+
+  if ((watch_class = class_create(THIS_MODULE, DEVICE_NAME)) == NULL) {
+    printk(KERN_ALERT "Failed to create class\n");
+    cdev_del(watch_cdev);
+    unregister_chrdev_region(dev_num, 1);
+    return -1;
+  }
+
+  if (device_create(watch_class, NULL, dev_num, NULL, DEVICE_NAME) == NULL) {
+    printk(KERN_ALERT "Failed to create device\n");
+    class_destroy(watch_class);
+    cdev_del(watch_cdev);
+    unregister_chrdev_region(dev_num, 1);
+    return -1;
+  }
+
+  printk(KERN_INFO "dev number: %d\n", dev_num);
+  printk(KERN_INFO "path: /dev/%s %d\n", DEVICE_NAME, dev_num);
+
+  fn_kallsyms_lookup_name_init();    // init kallsyms_lookup_name
+  LOOKUP_SYMS(stack_trace_save_tsk); // stack_trace_save_tsk
+  LOOKUP_SYMS(show_stack);           // show_stack
+  LOOKUP_SYMS(idle_sched_class);     // idle_sched_class
+  LOOKUP_SYMS(access_remote_vm);     // access_remote_vm
+
+  LOOKUP_SYMS_NORET(get_task_type); // get_task_type
+  LOOKUP_SYMS_NORET(kernfs_name);   // kernfs_name
+
+  return 0;
+}
+
+void cleanup_module(void) {
+  printk(KERN_INFO "%s\n", __FUNCTION__);
+  // clear all timer and page list
+  clear_all_watch();
+  // unmount
+  device_destroy(watch_class, dev_num);
+  class_destroy(watch_class);
+  cdev_del(watch_cdev);
+  unregister_chrdev_region(dev_num, 1);
+}
+
+MODULE_LICENSE("GPL");
\ No newline at end of file
diff --git a/kernel/monitor_kernel.h b/kernel/monitor_kernel.h
new file mode 100644
index 0000000..47e36d0
--- /dev/null
+++ b/kernel/monitor_kernel.h
@@ -0,0 +1,179 @@
+#include <linux/hrtimer.h>
+#include <linux/kprobes.h>
+#include <linux/ktime.h>
+#include <linux/list.h>
+#include <linux/slab.h> /*  for kmalloc */
+#include <linux/string.h>
+
+#include <asm/uaccess.h>
+#include <linux/cdev.h>
+#include <linux/highmem.h>
+#include <linux/sched.h>
+#include <linux/sched/loadavg.h> /* for avenrun, LOAD_* */
+#include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/stacktrace.h> /* for stack_trace_print */
+
+#define MAX_TIMER_NUM (128)      // max timer number
+#define TIMER_MAX_WATCH_NUM (32) // A timer max watch number at once time
+#define MAX_NAME_LEN (15)        // max name length
+typedef struct {
+  pid_t task_id;               // current process id
+  char name[MAX_NAME_LEN + 1]; // name
+  void *ptr;                   // virtual address
+  int length_byte;             // byte
+  long long threshold;         // threshold value
+  unsigned char unsigned_flag; // unsigned flag (true: unsigned, false: signed)
+  unsigned char greater_flag;  // reverse flag (true: >, false: <)
+  unsigned long time_ns;       // timer interval (ns)
+} watch_arg;
+
+typedef struct {
+  pid_t task_id;               // current process id
+  char name[MAX_NAME_LEN + 2]; // name, last char automatically add '\0'
+  void *kptr;                  // kernel address + offset
+  int length_byte;             // byte
+  long long threshold;         // threshold value
+  unsigned char unsigned_flag; // unsigned flag (true: unsigned, false: signed)
+  unsigned char greater_flag;  // reverse flag (true: >, false: <)
+} kernel_watch_arg;
+
+typedef struct {
+  unsigned long long time_ns; // hrTimer time interval (ns)
+  struct hrtimer hr_timer;    // hrTimer
+  ktime_t kt;                 // hrTimer time
+  unsigned sentinel;          // sentinel
+  kernel_watch_arg
+      k_watch_args[TIMER_MAX_WATCH_NUM]; // all watched kernel_watch_arg
+} kernel_watch_timer;
+
+#define TIMER_FILLED(timer) ((timer)->sentinel >= TIMER_MAX_WATCH_NUM)
+#define TIMER_EMPTY(timer) (!((timer)->time_ns | (timer)->sentinel))
+#define TIMER_NO_KWARG(timer) ((timer)->sentinel == 0)
+
+#define TIMER_START(timer)                                                     \
+  (hrtimer_start(&timer->hr_timer, timer->kt, HRTIMER_MODE_REL))
+#define TIMER_CANCEL(timer) (hrtimer_cancel(&timer->hr_timer))
+
+kernel_watch_timer kernel_wtimer_list[MAX_TIMER_NUM] = {
+    0};                    // all kernel_watch_timer
+int kernel_wtimer_num = 0; // current kernel_watch_timer number
+
+EXPORT_SYMBOL(kernel_wtimer_list); // export kernel_watch_timer_list
+EXPORT_SYMBOL(kernel_wtimer_num);  // export kernel_watch_timer_num
+
+// Helper function
+unsigned char w_arg2k_w_arg(void *ptr, watch_arg warg,
+                            kernel_watch_arg *k_watch_arg);
+
+// for timer
+kernel_watch_timer *get_timer(unsigned long long time_ns);
+unsigned char timer_add_watch(kernel_watch_timer *timer,
+                              kernel_watch_arg k_watch_arg);
+unsigned char timer_del_watch_by_pid(kernel_watch_timer *timer, pid_t pid);
+
+// for memory access
+typedef struct {
+  pid_t task_id; // current process id
+  struct page *page;
+  void *kaddr;
+  struct list_head entry;
+} watch_local_memory;
+
+static LIST_HEAD(watch_local_memory_list);
+
+void free_page_list(pid_t task_id);
+void free_all_page_list(void);
+
+// static struct page *page = NULL;
+// static void *kaddr = NULL;
+
+void *convert_user_space_ptr(pid_t pid, unsigned long kaddr);
+
+// for timer
+// #define US2NS (1000) // Interval in microseconds
+// static struct hrtimer hr_timer;
+// static ktime_t kt;
+
+// hrTimer
+enum hrtimer_restart check_variable_cb(struct hrtimer *timer);
+void start_all_hrTimer(void);
+void cancel_all_hrTimer(void);
+
+unsigned char read_and_compare(kernel_watch_arg *k_arg);
+
+// for diag_kallsyms_lookup_name
+unsigned long (*diag_kallsyms_lookup_name)(const char *name);
+static struct kprobe kprobe_kallsyms_lookup_name = {.symbol_name =
+                                                        "kallsyms_lookup_name"};
+
+int fn_kallsyms_lookup_name_init(void); // init kallsyms_lookup_name
+
+// form
+// https://github.com/alibaba/diagnose-tools/blob/8cd905a1c17f2201e460a2d607413a1303757a32/SOURCE/module/internal.h#L65
+// look for current function address, all the function with prefix "orig_" are
+#define LOOKUP_SYMS(name)                                                      \
+  do {                                                                         \
+    orig_##name = (void *)diag_kallsyms_lookup_name(#name);                    \
+    if (!orig_##name) {                                                        \
+      printk(KERN_ERR "kallsyms_lookup_name: %s\n", #name);                    \
+      return -EINVAL;                                                          \
+    }                                                                          \
+  } while (0)
+
+#define LOOKUP_SYMS_NORET(name)                                                \
+  do {                                                                         \
+    orig_##name = (void *)diag_kallsyms_lookup_name(#name);                    \
+    if (!orig_##name)                                                          \
+      pr_err("kallsyms_lookup_name: %s\n", #name);                             \
+  } while (0)
+
+#define BACKTRACE_DEPTH 20 // max stack depth
+
+// LOOKUP_SYMS(stack_trace_save_tsk);
+unsigned int (*orig_stack_trace_save_tsk)(struct task_struct *task,
+                                          unsigned long *store,
+                                          unsigned int size,
+                                          unsigned int skipnr);
+// LOOKUP_SYMS(show_stack);
+void (*orig_show_stack)(struct task_struct *task, unsigned long *sp,
+                        const char *loglvl);
+
+// https://www.spinics.net/lists/kernel/msg3582022.html
+// remove from 5.8.rc3,but it still work
+// whether the task contributes to the load
+#define __task_contributes_to_load(task)                                       \
+  ((READ_ONCE(task->__state) & TASK_UNINTERRUPTIBLE) != 0 &&                   \
+   (task->flags & PF_FROZEN) == 0 &&                                           \
+   (READ_ONCE(task->__state) & TASK_NOLOAD) == 0)
+
+/// @brief print all task stack
+/// @param
+static void print_task_stack(void) {
+  struct task_struct *g, *p;                // g: task group; p: task
+  unsigned long backtrace[BACKTRACE_DEPTH]; // save stack
+  unsigned int nr_bt;                       // stack depth
+  unsigned long long current_time;          // last time
+  current_time = ktime_get_real();
+  printk("Timestamp (ns): %lld\n", current_time);
+  printk("Recent Load: %lu.%02lu, %lu.%02lu, %lu.%02lu\n", // recent load
+         LOAD_INT(avenrun[0]), LOAD_FRAC(avenrun[0]), LOAD_INT(avenrun[1]),
+         LOAD_FRAC(avenrun[1]), LOAD_INT(avenrun[2]), LOAD_FRAC(avenrun[2]));
+  rcu_read_lock(); // lock run queue
+  // printk("Running task\n");
+  do_each_thread(g, p) {
+    if (p->__state == TASK_RUNNING || __task_contributes_to_load(p) ||
+        p->__state == TASK_IDLE) {
+      printk("task: %s, pid %d, state %d\n", p->comm, p->pid,
+             p->__state); //! todo
+      nr_bt = orig_stack_trace_save_tsk(p, backtrace, BACKTRACE_DEPTH, 0);
+      stack_trace_print(backtrace, nr_bt, 0); // print
+    }
+  }
+  while_each_thread(g, p);
+  rcu_read_unlock(); // unlock run queue
+}
+
+unsigned char del_all_kwarg_by_pid(pid_t pid);
+void clear_watch(pid_t pid);
+void clear_all_watch(void);
\ No newline at end of file
diff --git a/kernel/monitor_kernel_lib.c b/kernel/monitor_kernel_lib.c
new file mode 100644
index 0000000..3dea0cd
--- /dev/null
+++ b/kernel/monitor_kernel_lib.c
@@ -0,0 +1,427 @@
+#include "monitor_kernel.h"
+
+unsigned char w_arg2k_w_arg(void *ptr, watch_arg warg,
+                            kernel_watch_arg *k_watch_arg) {
+  // k_watch_arg init
+  k_watch_arg->task_id = warg.task_id;
+  strncpy(k_watch_arg->name, warg.name, MAX_NAME_LEN + 1); // name
+  k_watch_arg->name[MAX_NAME_LEN + 1] = '\0';              // just in case
+  k_watch_arg->kptr = ptr;
+  k_watch_arg->length_byte = warg.length_byte;
+  k_watch_arg->threshold = warg.threshold;
+  k_watch_arg->unsigned_flag = warg.unsigned_flag;
+  k_watch_arg->greater_flag = warg.greater_flag;
+  return 0;
+}
+
+/// @brief get a valuable timer
+/// @param time_ns
+/// @return kernel_watch_timer *, NULL means fail
+kernel_watch_timer *get_timer(unsigned long long time_ns) {
+  int i = 0;
+  kernel_watch_timer *timer = NULL;
+  // chose a timer
+  for (i = 0; i < kernel_wtimer_num; i++) {
+    timer = &kernel_wtimer_list[i];
+
+    if (TIMER_EMPTY(timer)) {
+      break;
+    }
+    if ((timer->time_ns == time_ns) && (!TIMER_FILLED(timer))) {
+      break;
+    }
+  }
+  // if all timer is full
+  if (i >= MAX_TIMER_NUM) {
+    printk(KERN_ERR "No timer available\n");
+    return NULL;
+  }
+  // if a new timer, init it
+  if (i > kernel_wtimer_num - 1) {
+    printk(KERN_INFO "New timer\n");
+
+    kernel_wtimer_list[i].time_ns = time_ns;
+    kernel_wtimer_list[i].sentinel = 0;
+
+    kernel_wtimer_list[i].kt = ktime_set(0, (unsigned long)time_ns); // ns
+    // CLOCK_MONOTONIC: time since boot | HRTIMER_MODE_REL : relative time
+    hrtimer_init(&(kernel_wtimer_list[i].hr_timer), CLOCK_MONOTONIC,
+                 HRTIMER_MODE_REL);
+    kernel_wtimer_list[i].hr_timer.function =
+        check_variable_cb; // callback function
+
+    kernel_wtimer_num = i + 1;
+  }
+  printk(KERN_INFO "now, we have %d timers\n", kernel_wtimer_num);
+  return &kernel_wtimer_list[i];
+}
+
+/// @brief hrTimer add watch
+/// @param timer
+/// @param k_watch_arg
+/// @return 0 is success
+unsigned char timer_add_watch(kernel_watch_timer *timer,
+                              kernel_watch_arg k_watch_arg) {
+  if (TIMER_FILLED(timer)) {
+    printk(KERN_ERR "Timer is full\n");
+    return -1;
+  }
+  memcpy(&timer->k_watch_args[timer->sentinel], &k_watch_arg,
+         sizeof(k_watch_arg));
+  // timer->k_watch_args[timer->sentinel] = k_watch_arg;
+  timer->sentinel++;
+  return 0;
+}
+
+unsigned char timer_del_watch_by_pid(kernel_watch_timer *timer, pid_t pid) {
+  int i = 0;
+  for (i = 0; i < timer->sentinel; i++) {
+    // if pid match, delete it and move the last one to this position, check
+    // again
+    if (timer->k_watch_args[i].task_id == pid) {
+      if (i != timer->sentinel - 1) {
+        memcpy(&timer->k_watch_args[i],
+               &timer->k_watch_args[timer->sentinel - 1],
+               sizeof(kernel_watch_arg));
+      }
+      timer->sentinel--;
+      i--;
+    }
+  }
+  return 0;
+}
+
+/// @brief transfer user space address to kernel space address
+///        change static global "kaddr" and "page" value
+/// @param pid: process id
+/// @param kaddr: user space address
+/// @return kernel space address + offset
+void *convert_user_space_ptr(pid_t pid, unsigned long addr) {
+  struct task_struct *task;
+  struct mm_struct *mm;
+  int ret;
+
+  // unsigned long aligned_addr = 0;
+  // unsigned long offset = 0;
+
+  watch_local_memory *node;
+
+  // if (addr < TASK_SIZE || addr > -PAGE_SIZE)
+  // {
+  //     printk(KERN_ERR "Invalid address\n");
+  //     return NULL;
+  // }
+
+  // for get_user_pages_remote
+  unsigned long aligned_addr = addr & PAGE_MASK;
+  unsigned long offset = addr & ~PAGE_MASK;
+
+  printk(KERN_INFO "%s\n", __FUNCTION__);
+
+  node = kmalloc(sizeof(watch_local_memory), GFP_KERNEL);
+  node->task_id = pid;
+
+  // Find the task with pid
+  rcu_read_lock();
+  task = pid_task(find_vpid(pid), PIDTYPE_PID);
+  rcu_read_unlock();
+
+  if (!task) {
+    printk(KERN_ERR "Cannot find task for PID %d\n", pid);
+    kfree(node); // careful there is kfree
+    return NULL;
+  }
+  // Get memory descriptor
+  mm = get_task_mm(task);
+  if (!mm) {
+    printk(KERN_ERR "Cannot get memory descriptor\n");
+    kfree(node); // careful there is kfree
+    return NULL;
+  }
+  down_read(&task->mm->mmap_lock);
+  ret = get_user_pages_remote(task->mm, aligned_addr, 1, FOLL_FORCE,
+                              &(node->page), NULL, NULL);
+  up_read(&task->mm->mmap_lock);
+
+  if (ret != 1) {
+    printk(KERN_ERR "Cannot get user page\n");
+    kfree(node); // careful there is kfree
+    return NULL;
+  }
+  // Map the page to kernel space
+  node->kaddr = kmap(node->page);
+  list_add_tail(&node->entry, &watch_local_memory_list); // add to list
+  // printk(KERN_INFO "node->kaddr: %p, aligned_addr: %ld, offset: %ld\n",
+  // node->kaddr, aligned_addr, offset);
+  return (void *)((unsigned long)(node->kaddr) + offset);
+}
+
+/// @brief free page in watch_local_memory_list with task_id
+/// @param task_id
+void free_page_list(pid_t task_id) {
+  watch_local_memory *node, *next;
+  list_for_each_entry_safe(node, next, &watch_local_memory_list, entry) {
+    if (node == NULL)
+      break;
+    if (node->task_id == task_id) {
+      // unmap and release the page
+      if (node->kaddr)
+        kunmap(node->kaddr);
+      if (node->page)
+        put_page(node->page);
+      list_del(&node->entry);
+      kfree(node); // careful there is kfree
+    }
+  }
+}
+
+/// @brief free all page in watch_local_memory_list
+/// @param
+void free_all_page_list(void) {
+  watch_local_memory *node, *next;
+  list_for_each_entry_safe(node, next, &watch_local_memory_list, entry) {
+    if (node == NULL)
+      break;
+    // unmap and release the page
+    if (node->kaddr)
+      kunmap(node->kaddr);
+    if (node->page)
+      put_page(node->page);
+    list_del(&node->entry);
+    kfree(node); // careful there is kfree
+  }
+}
+
+/// @brief hrTimer handler
+enum hrtimer_restart check_variable_cb(struct hrtimer *timer) {
+  kernel_watch_timer *k_watch_timer =
+      container_of(timer, kernel_watch_timer, hr_timer);
+  int i = 0, j = 0;
+  int buffer[TIMER_MAX_WATCH_NUM]; // Buffer to store the messages
+
+  // check all watched kernel_watch_arg
+  for (i = 0; i < k_watch_timer->sentinel; i++) {
+    if (read_and_compare(&k_watch_timer->k_watch_args[i])) {
+      // snprintf(buffer + strlen(buffer), sizeof(buffer) - strlen(buffer), "
+      // name: %s, threshold: %lld, pid: %d\n",
+      //          k_watch_timer->k_watch_args[i].name,
+      //          k_watch_timer->k_watch_args[i].threshold,
+      //          k_watch_timer->k_watch_args[i].task_id);
+      buffer[j] = i;
+      j++;
+
+      // printk(KERN_INFO "j: name %s, threshold: %lld\n",
+      // k_watch_timer->k_watch_args[i].name,
+      //        k_watch_timer->k_watch_args[i].threshold);
+      // printk(KERN_INFO "j: %d\n", j);
+    }
+  }
+  if (j > 0) // if any threshold reached
+  {
+    printk("-------------------------------------\n");
+    printk("-------------watch monitor-----------\n");
+    printk("Threshold reached:\n");
+
+    for (i = 0; i < j; i++) {
+      printk(" name: %s, threshold: %lld, pid: %d\n",
+             k_watch_timer->k_watch_args[buffer[i]].name, //! todo
+             k_watch_timer->k_watch_args[buffer[i]].threshold,
+             k_watch_timer->k_watch_args[buffer[i]].task_id);
+    }
+    print_task_stack();
+    // restart timer after 1s
+    hrtimer_forward(timer, timer->base->get_time(), ktime_set(1, 0)); //! todo
+    printk("-------------------------------------\n");
+  } else {
+    // keep frequency
+    hrtimer_forward(timer, timer->base->get_time(), k_watch_timer->kt);
+  }
+  return HRTIMER_RESTART; // restart timer
+}
+
+/// @brief start hrTimer
+/// @param timeout: timeout in us
+/// @return 0 is success
+// int start_hrTimer(unsigned long timeout)
+// {
+//     printk("HrTimer Start\n");
+
+//     kt = ktime_set(0, (unsigned long)timeout); //  us -> ns
+//     // CLOCK_MONOTONIC: time since boot | HRTIMER_MODE_REL : relative time
+//     hrtimer_init(&hr_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+//     hr_timer.function = check_variable_cb;
+//     // mode the same as hrtimer_init
+//     hrtimer_start(&hr_timer, kt, HRTIMER_MODE_REL);
+//     return 0;
+// }
+
+/// @brief start all hrTimer
+/// @param
+void start_all_hrTimer(void) {
+  int i = 0;
+  kernel_watch_timer *timer = NULL;
+  for (i = 0; i < kernel_wtimer_num; i++) {
+    timer = &(kernel_wtimer_list[i]);
+    TIMER_START(timer);
+  }
+  printk("HrTimer start,module keep %d hrtimer for now\n", kernel_wtimer_num);
+}
+
+/// @brief cancel hrTimer
+/// @param
+void cancel_all_hrTimer(void) {
+  int i = 0;
+  kernel_watch_timer *timer = NULL;
+  for (i = 0; i < kernel_wtimer_num; i++) {
+    timer = &(kernel_wtimer_list[i]);
+    TIMER_CANCEL(timer);
+  }
+
+  printk("HrTimer cancel,module keep %d hrtimer for now\n", kernel_wtimer_num);
+}
+
+// for read_and_compare
+typedef unsigned char (*compare_func)(void *, long long);
+
+unsigned char compare_1_byte_signed(void *ptr, long long threshold) {
+  // printk("compare_1_byte_signed: value %d, biss: %lld\n", *(char *)ptr,
+  // threshold);
+  return *(char *)ptr > threshold;
+}
+unsigned char compare_1_byte_unsigned(void *ptr, long long threshold) {
+  // printk("compare_1_byte_unsigned: value %d, biss: %lld\n", *(unsigned char
+  // *)ptr, threshold);
+  return *(unsigned char *)ptr > threshold;
+}
+unsigned char compare_2_byte_signed(void *ptr, long long threshold) {
+  // printk("compare_2_byte_signed: value %d, biss: %lld\n", *(short int *)ptr,
+  // threshold);
+  return *(short int *)ptr > threshold;
+}
+unsigned char compare_2_byte_unsigned(void *ptr, long long threshold) {
+  // printk("compare_2_byte_unsigned: value %d, biss: %lld\n", *(unsigned short
+  // int *)ptr, threshold);
+  return *(unsigned short int *)ptr > threshold;
+}
+unsigned char compare_4_byte_signed(void *ptr, long long threshold) {
+  // printk("compare_4_byte_signed: value %d, biss: %lld\n", *(int *)ptr,
+  // threshold);
+  return *(int *)ptr > threshold;
+}
+unsigned char compare_4_byte_unsigned(void *ptr, long long threshold) {
+  // printk("compare_4_byte_unsigned: value %d, biss: %lld\n", *(unsigned int
+  // *)ptr, threshold);
+  return *(unsigned int *)ptr > threshold;
+}
+unsigned char compare_8_byte_signed(void *ptr, long long threshold) {
+  // printk("compare_8_byte_signed: value %lld, biss: %lld\n", *(long long
+  // *)ptr, threshold);
+  return *(long long *)ptr > threshold;
+}
+unsigned char compare_8_byte_unsigned(void *ptr, long long threshold) {
+  // printk("compare_8_byte_unsigned: value %lld, biss: %lld\n", *(unsigned long
+  // long *)ptr, threshold);
+  return *(unsigned long long *)ptr > threshold;
+}
+// list of compare functions
+static compare_func compare_funcs[8] = {
+    compare_1_byte_signed,   compare_2_byte_signed,   compare_4_byte_signed,
+    compare_8_byte_signed,   compare_1_byte_unsigned, compare_2_byte_unsigned,
+    compare_4_byte_unsigned, compare_8_byte_unsigned};
+
+static int func_indices[2][9] = {{0, 0, 1, 0, 2, 0, 0, 0, 3},
+                                 {0, 4, 5, 0, 6, 0, 0, 0, 7}};
+
+/// @brief read k_arg->kptr and compare with threshold
+/// @param k_arg
+/// @return result of compare
+unsigned char read_and_compare(kernel_watch_arg *k_arg) {
+  void *ptr = k_arg->kptr;
+  int len = k_arg->length_byte;
+  unsigned char is_unsigned = k_arg->unsigned_flag;
+  long long threshold = k_arg->threshold;
+
+  unsigned char result = 0;
+
+  // if (len != 1 && len != 2 && len != 4 && len != 8)
+  // {
+  //     printk(KERN_ERR "Invalid length\n");
+  //     return 0;
+  // }
+
+  result = compare_funcs[func_indices[is_unsigned][len]](ptr, threshold);
+
+  // printk(KERN_INFO "read_and_compare: name %s, value %d, biss: %lld, result:
+  // %d \n", k_arg->name, *(int *)ptr,
+  //        threshold, result);
+
+  if (k_arg->greater_flag)
+    return result;
+  else
+    return !result;
+}
+
+/// @brief init kallsyms_lookup_name
+/// @param
+/// @return 0 is success
+int fn_kallsyms_lookup_name_init(void) {
+  register_kprobe(&kprobe_kallsyms_lookup_name);
+  diag_kallsyms_lookup_name = (void *)kprobe_kallsyms_lookup_name.addr;
+  unregister_kprobe(&kprobe_kallsyms_lookup_name);
+
+  printk("xby-debug, diag_kallsyms_lookup_name is %p\n",
+         diag_kallsyms_lookup_name);
+
+  if (!diag_kallsyms_lookup_name) {
+    return -EINVAL;
+  }
+  return 0;
+}
+
+unsigned char del_all_kwarg_by_pid(pid_t pid) {
+  int i = 0;
+  kernel_watch_timer *timer = NULL;
+
+  printk(KERN_INFO "del kwarg...");
+
+  for (i = 0; i < kernel_wtimer_num; i++) {
+    timer = &(kernel_wtimer_list[i]);
+    timer_del_watch_by_pid(timer, pid);
+  }
+  for (i = 0; i < kernel_wtimer_num; i++) {
+    timer = &(kernel_wtimer_list[i]);
+    if (TIMER_NO_KWARG(timer)) // no available kwarg
+    {
+      if (i != kernel_wtimer_num - 1) {
+        memcpy(timer, &kernel_wtimer_list[kernel_wtimer_num - 1],
+               sizeof(kernel_watch_timer));
+      }
+      kernel_wtimer_num--;
+      i--;
+    }
+  }
+  return 0;
+}
+
+/// @brief clear watch with pid
+/// @param pid
+void clear_watch(pid_t pid) {
+  printk(KERN_INFO "clear pid %d 's watch variable\n", pid);
+  cancel_all_hrTimer();      // just in case
+  del_all_kwarg_by_pid(pid); // delete all kwarg with pid
+  free_page_list(pid);       // free page with pid
+  start_all_hrTimer();       // restart timer
+}
+
+/// @brief clear all watch and reset kernel_wtimer_list/kernel_wtimer_num
+/// @param
+void clear_all_watch(void) {
+  printk(KERN_INFO "clear all watch variable\n");
+  // unmap and release the page
+  free_all_page_list();
+  // cancel timer
+  cancel_all_hrTimer();
+  // clear timer
+  kernel_wtimer_num = 0;
+  memset(kernel_wtimer_list, 0, sizeof(kernel_wtimer_list));
+}
\ No newline at end of file
diff --git a/kernel/monitor_kernel_task.c b/kernel/monitor_kernel_task.c
new file mode 100644
index 0000000..3b57152
--- /dev/null
+++ b/kernel/monitor_kernel_task.c
@@ -0,0 +1,377 @@
+#include "monitor_kernel_task.h"
+#include <asm/processor.h>
+#include <asm/ptrace.h>
+#include <asm/syscall.h> // for syscall_get_nr
+#include <linux/irq.h>
+#include <linux/sched/mm.h> // for get_task_mm
+#include <linux/syscalls.h>
+#include <linux/tracehook.h>
+
+struct stack_trace {
+  unsigned int nr_entries, max_entries;
+  unsigned long *entries;
+  int skip; /* input argument: How many entries to skip */
+};
+
+struct stack_frame_user {
+  const void __user *next_fp;
+  unsigned long ret_addr;
+};
+
+static inline int diag_get_task_type(struct task_struct *tsk) {
+  if (orig_get_task_type)
+    return orig_get_task_type(&tsk->se);
+  return 0;
+}
+
+static inline int orig_diag_cgroup_name(struct cgroup *cgrp, char *buf,
+                                        size_t buflen) {
+  if (orig_kernfs_name && cgrp && cgrp->kn) {
+    return orig_kernfs_name(cgrp->kn, buf, buflen);
+  } else {
+    return 0;
+  }
+}
+
+static inline mm_info *find_mm_info(mm_tree *mm_tree, struct mm_struct *mm) {
+  mm_info *info;
+  if (mm == NULL)
+    return NULL;
+  info = radix_tree_lookup(&mm_tree->mm_tree, (unsigned long)mm);
+  return info;
+}
+
+static void __diag_cgroup_name(struct task_struct *tsk, char *buf,
+                               unsigned int count, int cgroup) {
+  int cgroup_id = cpuacct_cgrp_id;
+
+  memset(buf, 0, count);
+
+  if (cgroup == 1) {
+    cgroup_id = cpuset_cgrp_id;
+  }
+
+  if (tsk && tsk->cgroups && tsk->cgroups->subsys &&
+      tsk->cgroups->subsys[cgroup_id] &&
+      tsk->cgroups->subsys[cgroup_id]->cgroup) {
+    orig_diag_cgroup_name(tsk->cgroups->subsys[cgroup_id]->cgroup, buf, count);
+  }
+}
+
+static void diag_cgroup_name(struct task_struct *tsk, char *buf,
+                             unsigned int count, int cgroup) {
+  __diag_cgroup_name(tsk, buf, count, cgroup);
+}
+
+static int copy_stack_frame(const void __user *fp,
+                            struct stack_frame_user *frame) {
+  int ret;
+
+  ret = 1;
+  pagefault_disable();
+  if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
+    ret = 0;
+  pagefault_enable();
+
+  return ret;
+}
+
+static int copy_stack_frame_remote(struct task_struct *tsk,
+                                   const void __user *fp,
+                                   struct stack_frame_user *frame) {
+  int ret;
+  struct mm_struct *mm;
+
+  mm = get_task_mm(tsk);
+  if (!mm)
+    return 0;
+
+  ret = orig_access_remote_vm(mm, (unsigned long)fp, frame, sizeof(*frame), 0);
+  mmput(mm);
+
+  return ret;
+}
+
+static inline void save_stack_trace_user_remote(struct task_struct *tsk,
+                                                struct stack_trace *trace) {
+  const struct pt_regs *regs = task_pt_regs(tsk);
+  const void __user *fp = (const void __user *)regs->bp;
+  int count = 0;
+
+  if (in_atomic() || irqs_disabled()) {
+    return;
+  }
+
+  if (trace->nr_entries < trace->max_entries)
+    trace->entries[trace->nr_entries++] = regs->ip;
+
+  while (trace->nr_entries < trace->max_entries) {
+    struct stack_frame_user frame;
+
+    frame.next_fp = NULL;
+    frame.ret_addr = 0;
+
+    if (!copy_stack_frame_remote(tsk, fp, &frame)) {
+      break;
+    }
+
+    if ((unsigned long)fp < regs->sp)
+      break;
+
+    if (frame.ret_addr) {
+      trace->entries[trace->nr_entries++] = frame.ret_addr;
+    } else
+      break;
+
+    if (fp == frame.next_fp)
+      break;
+    fp = frame.next_fp;
+
+    count++;
+    /**
+     * 线上环境发现这里有hardlockup，这里强制退出
+     */
+    if (count >= trace->max_entries || count >= 100)
+      break;
+  }
+}
+
+static inline void __save_stack_trace_user(struct stack_trace *trace) {
+  const struct pt_regs *regs = task_pt_regs(current);
+  const void __user *fp = (const void __user *)regs->bp;
+  int count = 0;
+
+  if (trace->nr_entries < trace->max_entries)
+    trace->entries[trace->nr_entries++] = regs->ip;
+
+  while (trace->nr_entries < trace->max_entries) {
+    struct stack_frame_user frame;
+
+    frame.next_fp = NULL;
+    frame.ret_addr = 0;
+    if (!copy_stack_frame(fp, &frame))
+      break;
+    if ((unsigned long)fp < regs->sp)
+      break;
+    if (frame.ret_addr) {
+      trace->entries[trace->nr_entries++] = frame.ret_addr;
+    }
+    if (fp == frame.next_fp)
+      break;
+    fp = frame.next_fp;
+    count++;
+    /**
+     * 线上环境发现这里有hardlockup，这里强制退出
+     */
+    if (count >= trace->max_entries || count >= 100)
+      break;
+  }
+}
+
+void perfect_save_stack_trace_user(struct stack_trace *trace) {
+  /*
+   * Trace user stack if we are not a kernel thread
+   */
+  if (current->mm) {
+    __save_stack_trace_user(trace);
+  }
+  if (trace->nr_entries < trace->max_entries)
+    trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void diagnose_save_stack_trace_user(unsigned long *backtrace) {
+  struct stack_trace trace;
+
+  memset(&trace, 0, sizeof(trace));
+  memset(backtrace, 0, BACKTRACE_DEPTH2 * sizeof(unsigned long));
+  trace.max_entries = BACKTRACE_DEPTH2;
+  trace.entries = backtrace;
+  perfect_save_stack_trace_user(&trace);
+}
+
+void diagnose_save_stack_trace_user_remote(struct task_struct *tsk,
+                                           unsigned long *backtrace) {
+  struct stack_trace trace;
+
+  memset(&trace, 0, sizeof(trace));
+  memset(backtrace, 0, BACKTRACE_DEPTH2 * sizeof(unsigned long));
+  trace.max_entries = BACKTRACE_DEPTH2;
+  trace.entries = backtrace;
+
+  /*
+   * Trace user stack if we are not a kernel thread
+   */
+  if (tsk->mm) {
+    save_stack_trace_user_remote(tsk, &trace);
+  }
+  if (trace.nr_entries < trace.max_entries)
+    trace.entries[trace.nr_entries++] = ULONG_MAX;
+}
+
+void diag_task_brief(struct task_struct *tsk, task_detail *detail) {
+  struct pid_namespace *ns;
+  struct pt_regs *task_regs;
+  struct task_struct *leader;
+  struct pt_regs *irq_regs;
+
+  if (!detail)
+    return;
+
+  memset(detail, 0, sizeof(task_detail));
+
+  if (!tsk || tsk->exit_state == EXIT_ZOMBIE) // zombie
+    return;
+  leader = tsk->group_leader;
+  if (!leader || leader->exit_state == EXIT_ZOMBIE) {
+    return;
+  }
+
+  if (tsk != current) { // not current task
+    detail->user_mode = -1;
+    detail->syscallno = -1;
+  } else if (!tsk->mm) { // current task but kernel thread
+    detail->user_mode = 0;
+    detail->syscallno = -1;
+  } else {                     // current task and user thread
+    irq_regs = get_irq_regs(); // get current irq regs
+    task_regs = task_pt_regs(tsk);
+
+    if ((irq_regs && user_mode(irq_regs)) ||
+        (task_regs && user_mode(task_regs))) {
+      detail->user_mode = 1; // user mode
+    } else {
+      detail->user_mode = 0; // kernel mode
+    }
+
+    if (task_regs) {
+      detail->syscallno = syscall_get_nr(tsk, task_regs); // get syscall no
+    }
+  }
+
+  if (tsk->sched_class == orig_idle_sched_class) // idle task
+    detail->sys_task = 2;
+  else if (!tsk->mm) // kernel thread
+    detail->sys_task = 1;
+  else
+    detail->sys_task = 0;
+
+  detail->pid = tsk->pid;                      // pid
+  detail->tgid = tsk->tgid;                    // tgid
+  detail->state = tsk->__state;                // state
+  detail->task_type = diag_get_task_type(tsk); // task type
+  ns = task_active_pid_ns(tsk);                // container pid
+  if (ns && ns != &init_pid_ns) {
+    detail->container_pid = task_pid_nr_ns(tsk, ns);
+    detail->container_tgid = task_tgid_nr_ns(tsk, ns);
+  } else {
+    detail->container_pid = tsk->pid;
+    detail->container_tgid = tsk->tgid;
+  }
+  strncpy(detail->comm, tsk->comm, TASK_COMM_LEN);
+  detail->comm[TASK_COMM_LEN - 1] = 0; // comm name
+  diag_cgroup_name(tsk, detail->cgroup_buf, CGROUP_NAME_LEN, 0);
+  diag_cgroup_name(tsk, detail->cgroup_cpuset, CGROUP_NAME_LEN, 1);
+
+  detail->cgroup_buf[CGROUP_NAME_LEN - 1] = 0;    // cgroup name
+  detail->cgroup_cpuset[CGROUP_NAME_LEN - 1] = 0; // cgroup cpuset name
+}
+
+void diag_task_user_stack(struct task_struct *tsk, user_stack_detail *detail) {
+  struct pt_regs *regs;
+  unsigned long sp, ip, bp;
+  struct task_struct *leader;
+
+  if (!detail)
+    return;
+
+  detail->stack[0] = 0;
+  if (!tsk || !tsk->mm)
+    return;
+
+  leader = tsk->group_leader;
+  if (!leader || !leader->mm || leader->exit_state == EXIT_ZOMBIE) {
+    return;
+  }
+
+  sp = 0;
+  ip = 0;
+  bp = 0;
+  regs = task_pt_regs(tsk);
+  if (regs) {
+    sp = regs->sp;
+#if defined(DIAG_ARM64)
+    ip = regs->pc;
+    bp = regs->sp;
+#else
+    ip = regs->ip;
+    bp = regs->bp;
+#endif
+  }
+#if defined(DIAG_ARM64)
+  detail->regs = regs->user_regs;
+#else
+  detail->regs = *regs;
+#endif
+  detail->sp = sp;
+  detail->ip = ip;
+  detail->bp = bp;
+
+  if (tsk == current) {
+    diagnose_save_stack_trace_user(detail->stack);
+  } else {
+    diagnose_save_stack_trace_user_remote(tsk, detail->stack);
+  }
+}
+
+void diag_task_kern_stack(struct task_struct *tsk, kern_stack_detail *detail) {
+  orig_stack_trace_save_tsk(tsk, detail->stack, BACKTRACE_DEPTH2, 0);
+}
+
+void dump_proc_chains_argv(int style, struct task_struct *tsk, mm_tree *mm_tree,
+                           proc_chains_detail *detail) {
+  struct task_struct *walker;
+  mm_info *mm_info;
+  int cnt = 0;
+  int i = 0;
+  struct task_struct *leader;
+
+  for (i = 0; i < PROCESS_CHAINS_COUNT; i++) {
+    detail->chains[i][0] = 0;
+    detail->tgid[i] = 0;
+  }
+  if (style == 0)
+    return;
+
+  if (!tsk || !tsk->mm)
+    return;
+
+  leader = tsk->group_leader;
+  if (!leader || !leader->mm ||
+      leader->exit_state == EXIT_ZOMBIE) { // leader is zombie or no mm
+    return;
+  }
+
+  rcu_read_lock();
+  walker = tsk;
+
+  while (walker->pid > 0) {
+    if (!thread_group_leader(walker))
+      walker = rcu_dereference(walker->group_leader);
+    mm_info = find_mm_info(mm_tree, walker->mm);
+    if (mm_info) {
+      if (mm_info->cgroup_buf[0] == 0)
+        diag_cgroup_name(walker, mm_info->cgroup_buf, 255, 0);
+      strncpy(detail->chains[cnt], mm_info->argv, PROCESS_ARGV_LEN);
+      detail->full_argv[cnt] = 1;
+    } else {
+      strncpy(detail->chains[cnt], walker->comm, TASK_COMM_LEN);
+      detail->full_argv[cnt] = 0;
+    }
+    detail->tgid[cnt] = walker->pid;
+    walker = rcu_dereference(walker->real_parent);
+    cnt++;
+    if (cnt >= PROCESS_CHAINS_COUNT)
+      break;
+  }
+  rcu_read_unlock();
+}
\ No newline at end of file
diff --git a/kernel/monitor_kernel_task.h b/kernel/monitor_kernel_task.h
new file mode 100644
index 0000000..62e501c
--- /dev/null
+++ b/kernel/monitor_kernel_task.h
@@ -0,0 +1,98 @@
+#include <linux/kernfs.h>
+#include <linux/sched.h>
+
+#define CGROUP_NAME_LEN 32 // max length of cgroup name
+#define TASK_COMM_LEN 16   // max length of task name
+
+#define BACKTRACE_DEPTH2 30 // max depth of backtrace
+
+#define PROCESS_CHAINS_COUNT 10 // max count of process chains
+#define PROCESS_ARGV_LEN 128    // max length of process argv
+
+// from
+// https://github.com/alibaba/diagnose-tools/blob/8cd905a1c17f2201e460a2d607413a1303757a32/SOURCE/uapi/ali_diagnose.h
+
+typedef struct {
+  char cgroup_buf[CGROUP_NAME_LEN];
+  char cgroup_cpuset[CGROUP_NAME_LEN];
+  int pid;
+  int tgid;
+  int container_pid;
+  int container_tgid;
+  long state;
+  int task_type;
+  unsigned long syscallno;
+  /**
+   * 0->user 1->sys 2->idle
+   */
+  unsigned long sys_task;
+  /**
+   * 1->user mode 0->sys mode -1->unknown
+   */
+  unsigned long user_mode;
+  char comm[TASK_COMM_LEN];
+} task_detail;
+
+typedef struct {
+  unsigned long stack[BACKTRACE_DEPTH2];
+} kern_stack_detail;
+
+typedef struct {
+  struct pt_regs regs;
+  unsigned long ip;
+  unsigned long bp;
+  unsigned long sp;
+  unsigned long stack[BACKTRACE_DEPTH2];
+} user_stack_detail;
+
+typedef struct {
+  unsigned int full_argv[PROCESS_CHAINS_COUNT];        //
+  char chains[PROCESS_CHAINS_COUNT][PROCESS_ARGV_LEN]; // process chains argv
+  unsigned int tgid[PROCESS_CHAINS_COUNT];             // process chains tgid
+} proc_chains_detail;
+
+// most important struct
+typedef struct {
+  int et_type;
+  unsigned long id;
+  unsigned long long tv;
+  task_detail task;               // brief
+  user_stack_detail user_stack;   // user stack
+  kern_stack_detail kern_stack;   // kernel stack
+  proc_chains_detail proc_chains; // process chains argv
+} variable_monitor_task;
+
+typedef struct {
+  struct rcu_head rcu_head;
+  pid_t pid;
+  struct mm_struct *mm;
+  char cgroup_buf[256];
+  char argv[256];
+} mm_info;
+
+typedef struct {
+  struct radix_tree_root mm_tree;
+  spinlock_t mm_tree_lock;
+} mm_tree;
+
+void diag_task_brief(struct task_struct *tsk,
+                     task_detail *detail); // get task brief
+void diag_task_user_stack(struct task_struct *tsk,
+                          user_stack_detail *detail); // get task user stack
+void diag_task_kern_stack(struct task_struct *tsk,
+                          kern_stack_detail *detail); // get task kernel stack
+void dump_proc_chains_argv(
+    int style, struct task_struct *tsk, mm_tree *mm_tree,
+    proc_chains_detail *detail); // get process chains argv
+
+// orig_X
+struct sched_class *orig_idle_sched_class;
+int (*orig_get_task_type)(struct sched_entity *se);
+int (*orig_kernfs_name)(struct kernfs_node *kn, char *buf, size_t buflen);
+int (*orig_access_remote_vm)(struct mm_struct *mm, unsigned long addr,
+                             void *buf, int len, unsigned int gup_flags);
+extern unsigned int (*orig_stack_trace_save_tsk)(struct task_struct *task,
+                                                 unsigned long *store,
+                                                 unsigned int size,
+                                                 unsigned int skipnr);
+