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);
69
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