// SPDX-License-Identifier: GPL-2.0

  /*
   * lib/smp_processor_id.c
   *
   * DEBUG_PREEMPT variant of smp_processor_id().
   */

  #include <linux/export.h>

  #include <linux/kprobes.h>

  #include <linux/sched.h>

  noinstr static

  unsigned int check_preemption_disabled(const char *what1, const char *what2)

  {

  	int this_cpu = raw_smp_processor_id();

  	if (likely(preempt_count()))

  		goto out;
  
  	if (irqs_disabled())
  		goto out;
  
  	/*
  	 * Kernel threads bound to a single CPU can safely use
  	 * smp_processor_id():
  	 */

  	if (current->nr_cpus_allowed == 1)

  		goto out;
  
  	/*
  	 * It is valid to assume CPU-locality during early bootup:
  	 */

  	if (system_state < SYSTEM_SCHEDULING)

  		goto out;
  
  	/*
  	 * Avoid recursion:
  	 */

  	preempt_disable_notrace();

  	instrumentation_begin();

  	if (!printk_ratelimit())
  		goto out_enable;

  	printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d
  ",
  		what1, what2, preempt_count() - 1, current->comm, current->pid);

  	printk("caller is %pS
  ", __builtin_return_address(0));

  	dump_stack();

  	instrumentation_end();

  
  out_enable:

  	preempt_enable_no_resched_notrace();

  out:
  	return this_cpu;
  }

  noinstr unsigned int debug_smp_processor_id(void)

  {
  	return check_preemption_disabled("smp_processor_id", "");
  }

  EXPORT_SYMBOL(debug_smp_processor_id);

  noinstr void __this_cpu_preempt_check(const char *op)

  {
  	check_preemption_disabled("__this_cpu_", op);
  }
  EXPORT_SYMBOL(__this_cpu_preempt_check);