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 /*
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 /*
30 * It is valid to assume CPU-locality during early bootup:
31 */
32 if (system_state < SYSTEM_SCHEDULING)
33 goto out;
34
35 /*
36 * Avoid recursion:
37 */
38 preempt_disable_notrace();
39
40 instrumentation_begin();
41 if (!printk_ratelimit())
42 goto out_enable;
43
44 printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
45 what1, what2, preempt_count() - 1, current->comm, current->pid);
46
47 printk("caller is %pS\n", __builtin_return_address(0));
48 dump_stack();
49 instrumentation_end();
50
51 out_enable:
52 preempt_enable_no_resched_notrace();
53 out:
54 return this_cpu;
55 }
56
debug_smp_processor_id(void)57 noinstr unsigned int debug_smp_processor_id(void)
58 {
59 return check_preemption_disabled("smp_processor_id", "");
60 }
61 EXPORT_SYMBOL(debug_smp_processor_id);
62
__this_cpu_preempt_check(const char * op)63 noinstr void __this_cpu_preempt_check(const char *op)
64 {
65 check_preemption_disabled("__this_cpu_", op);
66 }
67 EXPORT_SYMBOL(__this_cpu_preempt_check);
68
