lib/smp_processor_id.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * lib/smp_processor_id.c
   4  *
   5  * DEBUG_PREEMPT variant of smp_processor_id().
   6  */
   7 #include <linux/export.h>
   8 #include <linux/kprobes.h>
   9 #include <linux/sched.h>
  10
  11 noinstr static
  12 unsigned int check_preemption_disabled(const char *what1, const char *what2)
  13 {
  14         int this_cpu = raw_smp_processor_id();
  15
  16         if (likely(preempt_count()))
  17                 goto out;
  18
  19         if (irqs_disabled())
  20                 goto out;
  21
  22         if (is_percpu_thread())
  23                 goto out;
  24
  25 #ifdef CONFIG_SMP
  26         if (current->migration_disabled)
  27                 goto out;
  28 #endif
  29
  30         /*
  31          * It is valid to assume CPU-locality during early bootup:
  32          */
  33         if (system_state < SYSTEM_SCHEDULING)
  34                 goto out;
  35
  36         /*
  37          * Avoid recursion:
  38          */
  39         preempt_disable_notrace();
  40
  41         instrumentation_begin();
  42         if (!printk_ratelimit())
  43                 goto out_enable;
  44
  45         printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
  46                 what1, what2, preempt_count() - 1, current->comm, current->pid);
  47
  48         printk("caller is %pS\n", __builtin_return_address(0));
  49         dump_stack();
  50
  51 out_enable:
  52         instrumentation_end();
  53         preempt_enable_no_resched_notrace();
  54 out:
  55         return this_cpu;
  56 }
  57
  58 noinstr unsigned int debug_smp_processor_id(void)
  59 {
  60         return check_preemption_disabled("smp_processor_id", "");
  61 }
  62 EXPORT_SYMBOL(debug_smp_processor_id);
  63
  64 noinstr void __this_cpu_preempt_check(const char *op)
  65 {
  66         check_preemption_disabled("__this_cpu_", op);
  67 }
  68 EXPORT_SYMBOL(__this_cpu_preempt_check);