Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 /*
23 * Kernel threads bound to a single CPU can safely use
24 * smp_processor_id():
25 */
26 if (current->nr_cpus_allowed == 1)
27 goto out;
28
29#ifdef CONFIG_SMP
30 if (current->migration_disabled)
31 goto out;
32#endif
33
34 /*
35 * It is valid to assume CPU-locality during early bootup:
36 */
37 if (system_state < SYSTEM_SCHEDULING)
38 goto out;
39
40 /*
41 * Avoid recursion:
42 */
43 preempt_disable_notrace();
44
45 instrumentation_begin();
46 if (!printk_ratelimit())
47 goto out_enable;
48
49 printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
50 what1, what2, preempt_count() - 1, current->comm, current->pid);
51
52 printk("caller is %pS\n", __builtin_return_address(0));
53 dump_stack();
54 instrumentation_end();
55
56out_enable:
57 preempt_enable_no_resched_notrace();
58out:
59 return this_cpu;
60}
61
62noinstr unsigned int debug_smp_processor_id(void)
63{
64 return check_preemption_disabled("smp_processor_id", "");
65}
66EXPORT_SYMBOL(debug_smp_processor_id);
67
68noinstr void __this_cpu_preempt_check(const char *op)
69{
70 check_preemption_disabled("__this_cpu_", op);
71}
72EXPORT_SYMBOL(__this_cpu_preempt_check);