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 <asm/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 __kprobes 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 /* Account time spent with enabled wait psw loaded as idle time. */ 39 idle->sequence++; 40 smp_wmb(); 41 idle_time = idle->clock_idle_exit - idle->clock_idle_enter; 42 idle->clock_idle_enter = idle->clock_idle_exit = 0ULL; 43 idle->idle_time += idle_time; 44 idle->idle_count++; 45 account_idle_time(idle_time); 46 smp_wmb(); 47 idle->sequence++; 48 } 49 50 static ssize_t show_idle_count(struct device *dev, 51 struct device_attribute *attr, char *buf) 52 { 53 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 54 unsigned long long idle_count; 55 unsigned int sequence; 56 57 do { 58 sequence = ACCESS_ONCE(idle->sequence); 59 idle_count = ACCESS_ONCE(idle->idle_count); 60 if (ACCESS_ONCE(idle->clock_idle_enter)) 61 idle_count++; 62 } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); 63 return sprintf(buf, "%llu\n", idle_count); 64 } 65 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); 66 67 static ssize_t show_idle_time(struct device *dev, 68 struct device_attribute *attr, char *buf) 69 { 70 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); 71 unsigned long long now, idle_time, idle_enter, idle_exit; 72 unsigned int sequence; 73 74 do { 75 now = get_tod_clock(); 76 sequence = ACCESS_ONCE(idle->sequence); 77 idle_time = ACCESS_ONCE(idle->idle_time); 78 idle_enter = ACCESS_ONCE(idle->clock_idle_enter); 79 idle_exit = ACCESS_ONCE(idle->clock_idle_exit); 80 } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); 81 idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; 82 return sprintf(buf, "%llu\n", idle_time >> 12); 83 } 84 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL); 85 86 cputime64_t arch_cpu_idle_time(int cpu) 87 { 88 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); 89 unsigned long long now, idle_enter, idle_exit; 90 unsigned int sequence; 91 92 do { 93 now = get_tod_clock(); 94 sequence = ACCESS_ONCE(idle->sequence); 95 idle_enter = ACCESS_ONCE(idle->clock_idle_enter); 96 idle_exit = ACCESS_ONCE(idle->clock_idle_exit); 97 } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); 98 return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0; 99 } 100 101 void arch_cpu_idle_enter(void) 102 { 103 local_mcck_disable(); 104 } 105 106 void arch_cpu_idle(void) 107 { 108 if (!test_cpu_flag(CIF_MCCK_PENDING)) 109 /* Halt the cpu and keep track of cpu time accounting. */ 110 enabled_wait(); 111 local_irq_enable(); 112 } 113 114 void arch_cpu_idle_exit(void) 115 { 116 local_mcck_enable(); 117 if (test_cpu_flag(CIF_MCCK_PENDING)) 118 s390_handle_mcck(); 119 } 120 121 void arch_cpu_idle_dead(void) 122 { 123 cpu_die(); 124 } 125