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
11noinstr static
12unsigned 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	if (current->migration_disabled)
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	instrumentation_begin();
40	if (!printk_ratelimit())
41		goto out_enable;
42
43	printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
44		what1, what2, preempt_count() - 1, current->comm, current->pid);
45
46	printk("caller is %pS\n", __builtin_return_address(0));
47	dump_stack();
48
49out_enable:
50	instrumentation_end();
51	preempt_enable_no_resched_notrace();
52out:
53	return this_cpu;
54}
55
56noinstr unsigned int debug_smp_processor_id(void)
57{
58	return check_preemption_disabled("smp_processor_id", "");
59}
60EXPORT_SYMBOL(debug_smp_processor_id);
61
62noinstr void __this_cpu_preempt_check(const char *op)
63{
64	check_preemption_disabled("__this_cpu_", op);
65}
66EXPORT_SYMBOL(__this_cpu_preempt_check);