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 /* 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 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 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