1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Idle functions for s390. 4 * 5 * Copyright IBM Corp. 2014 6 * 7 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/kernel_stat.h> 12 #include <linux/kprobes.h> 13 #include <linux/notifier.h> 14 #include <linux/init.h> 15 #include <linux/cpu.h> 16 #include <linux/sched/cputime.h> 17 #include <asm/nmi.h> 18 #include <asm/smp.h> 19 #include "entry.h" 20 21 static DEFINE_PER_CPU(struct s390_idle_data, s390_idle); 22 23 void enabled_wait(void) 24 { 25 struct s390_idle_data *idle = this_cpu_ptr(&s390_idle); 26 unsigned long long idle_time; 27 unsigned long psw_mask; 28 29 trace_hardirqs_on(); 30 31 /* Wait for external, I/O or machine check interrupt. */ 32 psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT | 33 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; 34 clear_cpu_flag(CIF_NOHZ_DELAY); 35 36 /* Call the assembler magic in entry.S */ 37 psw_idle(idle, psw_mask); 38 39 trace_hardirqs_off(); 40 41 /* Account time spent with enabled wait psw loaded as idle time. */ 42 write_seqcount_begin(&idle->seqcount); 43 idle_time = idle->clock_idle_exit - idle->clock_idle_enter; 44 idle->clock_idle_enter = idle->clock_idle_exit = 0ULL; 45 idle->idle_time += idle_time; 46 idle->idle_count++; 47 account_idle_time(cputime_to_nsecs(idle_time)); 48 write_seqcount_end(&idle->seqcount); 49 } 50 NOKPROBE_SYMBOL(enabled_wait); 51 52 static ssize_t show_idle_count(struct device *dev, 53 struct device_attribute *attr, char *buf) 54 { 55 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 56 unsigned long long idle_count; 57 unsigned int seq; 58 59 do { 60 seq = read_seqcount_begin(&idle->seqcount); 61 idle_count = READ_ONCE(idle->idle_count); 62 if (READ_ONCE(idle->clock_idle_enter)) 63 idle_count++; 64 } while (read_seqcount_retry(&idle->seqcount, seq)); 65 return sprintf(buf, "%llu\n", idle_count); 66 } 67 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); 68 69 static ssize_t show_idle_time(struct device *dev, 70 struct device_attribute *attr, char *buf) 71 { 72 unsigned long long now, idle_time, idle_enter, idle_exit, in_idle; 73 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 74 unsigned int seq; 75 76 do { 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 in_idle = 0; 83 now = get_tod_clock(); 84 if (idle_enter) { 85 if (idle_exit) { 86 in_idle = idle_exit - idle_enter; 87 } else if (now > idle_enter) { 88 in_idle = now - idle_enter; 89 } 90 } 91 idle_time += in_idle; 92 return sprintf(buf, "%llu\n", idle_time >> 12); 93 } 94 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL); 95 96 u64 arch_cpu_idle_time(int cpu) 97 { 98 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); 99 unsigned long long now, idle_enter, idle_exit, in_idle; 100 unsigned int seq; 101 102 do { 103 seq = read_seqcount_begin(&idle->seqcount); 104 idle_enter = READ_ONCE(idle->clock_idle_enter); 105 idle_exit = READ_ONCE(idle->clock_idle_exit); 106 } while (read_seqcount_retry(&idle->seqcount, seq)); 107 in_idle = 0; 108 now = get_tod_clock(); 109 if (idle_enter) { 110 if (idle_exit) { 111 in_idle = idle_exit - idle_enter; 112 } else if (now > idle_enter) { 113 in_idle = now - idle_enter; 114 } 115 } 116 return cputime_to_nsecs(in_idle); 117 } 118 119 void arch_cpu_idle_enter(void) 120 { 121 local_mcck_disable(); 122 } 123 124 void arch_cpu_idle(void) 125 { 126 if (!test_cpu_flag(CIF_MCCK_PENDING)) 127 /* Halt the cpu and keep track of cpu time accounting. */ 128 enabled_wait(); 129 local_irq_enable(); 130 } 131 132 void arch_cpu_idle_exit(void) 133 { 134 local_mcck_enable(); 135 if (test_cpu_flag(CIF_MCCK_PENDING)) 136 s390_handle_mcck(); 137 } 138 139 void arch_cpu_idle_dead(void) 140 { 141 cpu_die(); 142 } 143