Linux 内核中的 percpu 指针是如何实现的

#include 
DEFINE_PER_CPU(int, my_variable);

int cpu;
int *percpu_ptr;
cpu = get_cpu();
percpu_ptr = this_cpu_ptr(&my_variable);
*percpu_ptr = 42;
put_cpu();

c
#include 
DEFINE_PER_CPU(int, my_variable);
void my_function(void)
{
    int *percpu_ptr;
    percpu_ptr = this_cpu_ptr(&my_variable);
    *percpu_ptr = 42;
}
void another_function(void)
{
    int *percpu_ptr;
    percpu_ptr = this_cpu_ptr(&my_variable);
    printk(KERN_INFO "The value is %d\n", *percpu_ptr);
}