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
check_preemption_disabled(const char * what1,const char * what2)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 
debug_smp_processor_id(void)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 
__this_cpu_preempt_check(const char * op)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);
69