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 #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 56 out_enable: 57 preempt_enable_no_resched_notrace(); 58 out: 59 return this_cpu; 60 } 61 62 noinstr unsigned int debug_smp_processor_id(void) 63 { 64 return check_preemption_disabled("smp_processor_id", ""); 65 } 66 EXPORT_SYMBOL(debug_smp_processor_id); 67 68 noinstr void __this_cpu_preempt_check(const char *op) 69 { 70 check_preemption_disabled("__this_cpu_", op); 71 } 72 EXPORT_SYMBOL(__this_cpu_preempt_check); 73