#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>

typedef struct {
  struct rcu_head rcu_head;
  pid_t pid;
  struct mm_struct *mm;
  char cgroup_buf[256];
  char argv[256];
} mm_info;

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;
  }
}

static 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;
}

static 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);
}

static 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();
}