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Linux kernel mirror (for testing)
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linux
1/**
2 * @file nmi_timer_int.c
3 *
4 * @remark Copyright 2011 Advanced Micro Devices, Inc.
5 *
6 * @author Robert Richter <robert.richter@amd.com>
7 */
8
9#include <linux/init.h>
10#include <linux/smp.h>
11#include <linux/errno.h>
12#include <linux/oprofile.h>
13#include <linux/perf_event.h>
14
15#ifdef CONFIG_OPROFILE_NMI_TIMER
16
17static DEFINE_PER_CPU(struct perf_event *, nmi_timer_events);
18static int ctr_running;
19
20static struct perf_event_attr nmi_timer_attr = {
21 .type = PERF_TYPE_HARDWARE,
22 .config = PERF_COUNT_HW_CPU_CYCLES,
23 .size = sizeof(struct perf_event_attr),
24 .pinned = 1,
25 .disabled = 1,
26};
27
28static void nmi_timer_callback(struct perf_event *event,
29 struct perf_sample_data *data,
30 struct pt_regs *regs)
31{
32 event->hw.interrupts = 0; /* don't throttle interrupts */
33 oprofile_add_sample(regs, 0);
34}
35
36static int nmi_timer_start_cpu(int cpu)
37{
38 struct perf_event *event = per_cpu(nmi_timer_events, cpu);
39
40 if (!event) {
41 event = perf_event_create_kernel_counter(&nmi_timer_attr, cpu, NULL,
42 nmi_timer_callback, NULL);
43 if (IS_ERR(event))
44 return PTR_ERR(event);
45 per_cpu(nmi_timer_events, cpu) = event;
46 }
47
48 if (event && ctr_running)
49 perf_event_enable(event);
50
51 return 0;
52}
53
54static void nmi_timer_stop_cpu(int cpu)
55{
56 struct perf_event *event = per_cpu(nmi_timer_events, cpu);
57
58 if (event && ctr_running)
59 perf_event_disable(event);
60}
61
62static int nmi_timer_cpu_online(unsigned int cpu)
63{
64 nmi_timer_start_cpu(cpu);
65 return 0;
66}
67static int nmi_timer_cpu_predown(unsigned int cpu)
68{
69 nmi_timer_stop_cpu(cpu);
70 return 0;
71}
72
73static int nmi_timer_start(void)
74{
75 int cpu;
76
77 get_online_cpus();
78 ctr_running = 1;
79 for_each_online_cpu(cpu)
80 nmi_timer_start_cpu(cpu);
81 put_online_cpus();
82
83 return 0;
84}
85
86static void nmi_timer_stop(void)
87{
88 int cpu;
89
90 get_online_cpus();
91 for_each_online_cpu(cpu)
92 nmi_timer_stop_cpu(cpu);
93 ctr_running = 0;
94 put_online_cpus();
95}
96
97static enum cpuhp_state hp_online;
98
99static void nmi_timer_shutdown(void)
100{
101 struct perf_event *event;
102 int cpu;
103
104 cpuhp_remove_state(hp_online);
105 for_each_possible_cpu(cpu) {
106 event = per_cpu(nmi_timer_events, cpu);
107 if (!event)
108 continue;
109 perf_event_disable(event);
110 per_cpu(nmi_timer_events, cpu) = NULL;
111 perf_event_release_kernel(event);
112 }
113}
114
115static int nmi_timer_setup(void)
116{
117 int err;
118 u64 period;
119
120 /* clock cycles per tick: */
121 period = (u64)cpu_khz * 1000;
122 do_div(period, HZ);
123 nmi_timer_attr.sample_period = period;
124
125 err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "oprofile/nmi:online",
126 nmi_timer_cpu_online, nmi_timer_cpu_predown);
127 if (err < 0) {
128 nmi_timer_shutdown();
129 return err;
130 }
131 hp_online = err;
132 return 0;
133}
134
135int __init op_nmi_timer_init(struct oprofile_operations *ops)
136{
137 int err = 0;
138
139 err = nmi_timer_setup();
140 if (err)
141 return err;
142 nmi_timer_shutdown(); /* only check, don't alloc */
143
144 ops->create_files = NULL;
145 ops->setup = nmi_timer_setup;
146 ops->shutdown = nmi_timer_shutdown;
147 ops->start = nmi_timer_start;
148 ops->stop = nmi_timer_stop;
149 ops->cpu_type = "timer";
150
151 printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
152
153 return 0;
154}
155
156#endif