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
enabled_wait(void)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
show_idle_count(struct device * dev,struct device_attribute * attr,char * buf)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
show_idle_time(struct device * dev,struct device_attribute * attr,char * buf)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
arch_cpu_idle_time(int cpu)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
arch_cpu_idle_enter(void)101 void arch_cpu_idle_enter(void)
102 {
103 local_mcck_disable();
104 }
105
arch_cpu_idle(void)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
arch_cpu_idle_exit(void)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
arch_cpu_idle_dead(void)121 void arch_cpu_idle_dead(void)
122 {
123 cpu_die();
124 }
125