1 /* 2 * Idle functions for s390. 3 * 4 * Copyright IBM Corp. 2014 5 * 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/kernel_stat.h> 11 #include <linux/kprobes.h> 12 #include <linux/notifier.h> 13 #include <linux/init.h> 14 #include <linux/cpu.h> 15 #include <linux/sched/cputime.h> 16 #include <asm/nmi.h> 17 #include <asm/smp.h> 18 #include "entry.h" 19 20 static DEFINE_PER_CPU(struct s390_idle_data, s390_idle); 21 22 void enabled_wait(void) 23 { 24 struct s390_idle_data *idle = this_cpu_ptr(&s390_idle); 25 unsigned long long idle_time; 26 unsigned long psw_mask; 27 28 trace_hardirqs_on(); 29 30 /* Wait for external, I/O or machine check interrupt. */ 31 psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT | 32 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 33 clear_cpu_flag(CIF_NOHZ_DELAY); 34 35 /* Call the assembler magic in entry.S */ 36 psw_idle(idle, psw_mask); 37 38 trace_hardirqs_off(); 39 40 /* Account time spent with enabled wait psw loaded as idle time. */ 41 write_seqcount_begin(&idle->seqcount); 42 idle_time = idle->clock_idle_exit - idle->clock_idle_enter; 43 idle->clock_idle_enter = idle->clock_idle_exit = 0ULL; 44 idle->idle_time += idle_time; 45 idle->idle_count++; 46 account_idle_time(cputime_to_nsecs(idle_time)); 47 write_seqcount_end(&idle->seqcount); 48 } 49 NOKPROBE_SYMBOL(enabled_wait); 50 51 static ssize_t show_idle_count(struct device *dev, 52 struct device_attribute *attr, char *buf) 53 { 54 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 55 unsigned long long idle_count; 56 unsigned int seq; 57 58 do { 59 seq = read_seqcount_begin(&idle->seqcount); 60 idle_count = READ_ONCE(idle->idle_count); 61 if (READ_ONCE(idle->clock_idle_enter)) 62 idle_count++; 63 } while (read_seqcount_retry(&idle->seqcount, seq)); 64 return sprintf(buf, "%llu\n", idle_count); 65 } 66 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); 67 68 static ssize_t show_idle_time(struct device *dev, 69 struct device_attribute *attr, char *buf) 70 { 71 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 72 unsigned long long now, idle_time, idle_enter, idle_exit; 73 unsigned int seq; 74 75 do { 76 now = get_tod_clock(); 77 seq = read_seqcount_begin(&idle->seqcount); 78 idle_time = READ_ONCE(idle->idle_time); 79 idle_enter = READ_ONCE(idle->clock_idle_enter); 80 idle_exit = READ_ONCE(idle->clock_idle_exit); 81 } while (read_seqcount_retry(&idle->seqcount, seq)); 82 idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; 83 return sprintf(buf, "%llu\n", idle_time >> 12); 84 } 85 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL); 86 87 u64 arch_cpu_idle_time(int cpu) 88 { 89 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); 90 unsigned long long now, idle_enter, idle_exit; 91 unsigned int seq; 92 93 do { 94 now = get_tod_clock(); 95 seq = read_seqcount_begin(&idle->seqcount); 96 idle_enter = READ_ONCE(idle->clock_idle_enter); 97 idle_exit = READ_ONCE(idle->clock_idle_exit); 98 } while (read_seqcount_retry(&idle->seqcount, seq)); 99 100 return cputime_to_nsecs(idle_enter ? ((idle_exit ?: now) - idle_enter) : 0); 101 } 102 103 void arch_cpu_idle_enter(void) 104 { 105 local_mcck_disable(); 106 } 107 108 void arch_cpu_idle(void) 109 { 110 if (!test_cpu_flag(CIF_MCCK_PENDING)) 111 /* Halt the cpu and keep track of cpu time accounting. */ 112 enabled_wait(); 113 local_irq_enable(); 114 } 115 116 void arch_cpu_idle_exit(void) 117 { 118 local_mcck_enable(); 119 if (test_cpu_flag(CIF_MCCK_PENDING)) 120 s390_handle_mcck(); 121 } 122 123 void arch_cpu_idle_dead(void) 124 { 125 cpu_die(); 126 } 127