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review.trustedfirmware.org / hafnium / third_party / linux.git / 3a0ad55d848b50499b68d7141d4eca997fce28ef / . / arch / s390 / kernel / idle.c
blob: b9d8fe45737aa2e529cb9eec244349e121803858 [file] [log] [blame]
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000[diff] [blame]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
21static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
22
23void 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}
50NOKPROBE_SYMBOL(enabled_wait);
51
52static 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}
67DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
68
69static ssize_t show_idle_time(struct device *dev,
70 struct device_attribute *attr, char *buf)
71{
72 struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
73 unsigned long long now, idle_time, idle_enter, idle_exit;
74 unsigned int seq;
75
76 do {
77 now = get_tod_clock();
78 seq = read_seqcount_begin(&idle->seqcount);
79 idle_time = READ_ONCE(idle->idle_time);
80 idle_enter = READ_ONCE(idle->clock_idle_enter);
81 idle_exit = READ_ONCE(idle->clock_idle_exit);
82 } while (read_seqcount_retry(&idle->seqcount, seq));
83 idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
84 return sprintf(buf, "%llu\n", idle_time >> 12);
85}
86DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
87
88u64 arch_cpu_idle_time(int cpu)
89{
90 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
91 unsigned long long now, idle_enter, idle_exit;
92 unsigned int seq;
93
94 do {
95 now = get_tod_clock();
96 seq = read_seqcount_begin(&idle->seqcount);
97 idle_enter = READ_ONCE(idle->clock_idle_enter);
98 idle_exit = READ_ONCE(idle->clock_idle_exit);
99 } while (read_seqcount_retry(&idle->seqcount, seq));
100
101 return cputime_to_nsecs(idle_enter ? ((idle_exit ?: now) - idle_enter) : 0);
102}
103
104void arch_cpu_idle_enter(void)
105{
106 local_mcck_disable();
107}
108
109void arch_cpu_idle(void)
110{
111 if (!test_cpu_flag(CIF_MCCK_PENDING))
112 /* Halt the cpu and keep track of cpu time accounting. */
113 enabled_wait();
114 local_irq_enable();
115}
116
117void arch_cpu_idle_exit(void)
118{
119 local_mcck_enable();
120 if (test_cpu_flag(CIF_MCCK_PENDING))
121 s390_handle_mcck();
122}
123
124void arch_cpu_idle_dead(void)
125{
126 cpu_die();
127}