#include "monitor_perf.h"

static struct perf_event *pe;

void vm_perf_overflow_callback(struct perf_event *event,
                               struct perf_sample_data *data,
                               struct pt_regs *regs) {
  // handle perf event data
  // struct perf_callchain_entry *callchain;
  // int nr, i;

  pr_info("perf event callback\n");
  
  perf_event_disable(event);

  // 如果 perf_sample_data 有调用堆栈信息
  // if (data->callchain) {
  //   callchain = data->callchain;
  //   nr = callchain->nr; // 调用堆栈的长度

  //   // 遍历堆栈条目并处理它们
  //   for (i = 0; i < nr; i++) {
  //     // callchain->ip[i] 包含了堆栈的每个条目
  //     // 在这里可以调用 to_buff 将堆栈信息写入缓冲区
  //     //   to_buff(&callchain->ip[i], sizeof(callchain->ip[i]));
  //     pr_info("callchain->ip[%d] = %llx\n", i, callchain->ip[i]);
  //   }
  // }
}

// static struct perf_event_attr pea = {
//     .type = PERF_TYPE_SOFTWARE,             // software event
//     .size = sizeof(struct perf_event_attr), // size of attr
//     .config = PERF_COUNT_SW_CPU_CLOCK,          // no care
//     PERF_COUNT_SW_DUMMY PERF_COUNT_SW_CPU_CLOCK .sample_period = 1, // sample
//     every 1 event .sample_type =
//         PERF_SAMPLE_CALLCHAIN, // sample callchain | means include stacktrace
//     // .exclude_kernel = 1, // no kernel stacktrace | may need to change
//     after test
//     // .exclude_hv = 1, // no hypervisor stacktrace | may need to change
//     after test .disabled = 0,   // disabled at first
// };

struct perf_event_attr pea = {
    .type = PERF_TYPE_SOFTWARE,
    .size = sizeof(struct perf_event_attr),
    .config = PERF_COUNT_SW_CPU_CLOCK,
    .sample_period = 1,
    .sample_type = PERF_SAMPLE_CALLCHAIN,
    .disabled = 1,
};

#include <linux/cpumask.h>
#include <linux/smp.h>
/**
 * @brief Set the up perf event for task object
 *
 * @param tsk
 */
void setup_perf_event_for_task(struct task_struct *tsk) {
  pr_info("setup_perf_event_for_task: cpu = %d\n", tsk->on_cpu);
  if (pe) {
    pr_info("Perf event already created\n");
    return;
  }
  
  // int cpu;
  // struct perf_event **events;
  // for_each_possible_cpu(cpu) {
  //   struct perf_event **event = per_cpu_ptr(events, cpu);
  //   if (cpu_is_offline(cpu)) {
  //     pr_info("cpu %d is offline\n", cpu);
  //     *event = NULL;
  //     continue;
  //   }
  //   *event = perf_event_create_kernel_counter(&pea, cpu, tsk,
  //                                             vm_perf_overflow_callback, NULL);

  //   // perf_event_create_kernel_counter(&pea, cpu, tsk,
  //   // vm_perf_overflow_callback,
  //   //                                  NULL);
  //   if (IS_ERR(*event)) {
  //     printk(KERN_INFO "create perf event failure\n");
  //     // return -1;
  //   }
  //   perf_event_enable(*event);
  // }

  // pe = perf_event_create_kernel_counter(&pea, tsk->on_cpu, tsk,
  //                                         vm_perf_overflow_callback, NULL);
  pe = perf_event_create_kernel_counter(&pea, -1, tsk,
                                        vm_perf_overflow_callback, NULL);
  if (IS_ERR(pe)) {
    pr_info("Error in perf_event_create_kernel_counter\n");
    return;
  }

  perf_event_enable(pe); // enable perf event
}

/**
 * @brief Disable perf event
 *
 */
void cleanup_perf_event(void) {
  if (pe) {
    perf_event_disable(pe);
    perf_event_release_kernel(pe);
    pe = NULL;
  }
}