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/sched.h>
9
check_preemption_disabled(const char * what1,const char * what2)10 notrace static unsigned int check_preemption_disabled(const char *what1,
11 const char *what2)
12 {
13 int this_cpu = raw_smp_processor_id();
14
15 if (likely(preempt_count()))
16 goto out;
17
18 if (irqs_disabled())
19 goto out;
20
21 /*
22 * Kernel threads bound to a single CPU can safely use
23 * smp_processor_id():
24 */
25 if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu)))
26 goto out;
27
28 /*
29 * It is valid to assume CPU-locality during early bootup:
30 */
31 if (system_state < SYSTEM_SCHEDULING)
32 goto out;
33
34 /*
35 * Avoid recursion:
36 */
37 preempt_disable_notrace();
38
39 if (!printk_ratelimit())
40 goto out_enable;
41
42 printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
43 what1, what2, preempt_count() - 1, current->comm, current->pid);
44
45 printk("caller is %pS\n", __builtin_return_address(0));
46 dump_stack();
47
48 out_enable:
49 preempt_enable_no_resched_notrace();
50 out:
51 return this_cpu;
52 }
53
debug_smp_processor_id(void)54 notrace unsigned int debug_smp_processor_id(void)
55 {
56 return check_preemption_disabled("smp_processor_id", "");
57 }
58 EXPORT_SYMBOL(debug_smp_processor_id);
59
__this_cpu_preempt_check(const char * op)60 notrace void __this_cpu_preempt_check(const char *op)
61 {
62 check_preemption_disabled("__this_cpu_", op);
63 }
64 EXPORT_SYMBOL(__this_cpu_preempt_check);
65