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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 | |
17 | static DEFINE_PER_CPU(struct perf_event *, nmi_timer_events); |
18 | static int ctr_running; |
19 | |
20 | static 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 | |
28 | static 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 | |
36 | static 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 | |
54 | static 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 | |
62 | static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action, |
63 | void *data) |
64 | { |
65 | int cpu = (unsigned long)data; |
66 | switch (action) { |
67 | case CPU_DOWN_FAILED: |
68 | case CPU_ONLINE: |
69 | nmi_timer_start_cpu(cpu); |
70 | break; |
71 | case CPU_DOWN_PREPARE: |
72 | nmi_timer_stop_cpu(cpu); |
73 | break; |
74 | } |
75 | return NOTIFY_DONE; |
76 | } |
77 | |
78 | static struct notifier_block nmi_timer_cpu_nb = { |
79 | .notifier_call = nmi_timer_cpu_notifier |
80 | }; |
81 | |
82 | static int nmi_timer_start(void) |
83 | { |
84 | int cpu; |
85 | |
86 | get_online_cpus(); |
87 | ctr_running = 1; |
88 | for_each_online_cpu(cpu) |
89 | nmi_timer_start_cpu(cpu); |
90 | put_online_cpus(); |
91 | |
92 | return 0; |
93 | } |
94 | |
95 | static void nmi_timer_stop(void) |
96 | { |
97 | int cpu; |
98 | |
99 | get_online_cpus(); |
100 | for_each_online_cpu(cpu) |
101 | nmi_timer_stop_cpu(cpu); |
102 | ctr_running = 0; |
103 | put_online_cpus(); |
104 | } |
105 | |
106 | static void nmi_timer_shutdown(void) |
107 | { |
108 | struct perf_event *event; |
109 | int cpu; |
110 | |
111 | get_online_cpus(); |
112 | unregister_cpu_notifier(&nmi_timer_cpu_nb); |
113 | for_each_possible_cpu(cpu) { |
114 | event = per_cpu(nmi_timer_events, cpu); |
115 | if (!event) |
116 | continue; |
117 | perf_event_disable(event); |
118 | per_cpu(nmi_timer_events, cpu) = NULL; |
119 | perf_event_release_kernel(event); |
120 | } |
121 | |
122 | put_online_cpus(); |
123 | } |
124 | |
125 | static int nmi_timer_setup(void) |
126 | { |
127 | int cpu, err; |
128 | u64 period; |
129 | |
130 | /* clock cycles per tick: */ |
131 | period = (u64)cpu_khz * 1000; |
132 | do_div(period, HZ); |
133 | nmi_timer_attr.sample_period = period; |
134 | |
135 | get_online_cpus(); |
136 | err = register_cpu_notifier(&nmi_timer_cpu_nb); |
137 | if (err) |
138 | goto out; |
139 | /* can't attach events to offline cpus: */ |
140 | for_each_online_cpu(cpu) { |
141 | err = nmi_timer_start_cpu(cpu); |
142 | if (err) |
143 | break; |
144 | } |
145 | if (err) |
146 | nmi_timer_shutdown(); |
147 | out: |
148 | put_online_cpus(); |
149 | return err; |
150 | } |
151 | |
152 | int __init op_nmi_timer_init(struct oprofile_operations *ops) |
153 | { |
154 | int err = 0; |
155 | |
156 | err = nmi_timer_setup(); |
157 | if (err) |
158 | return err; |
159 | nmi_timer_shutdown(); /* only check, don't alloc */ |
160 | |
161 | ops->create_files = NULL; |
162 | ops->setup = nmi_timer_setup; |
163 | ops->shutdown = nmi_timer_shutdown; |
164 | ops->start = nmi_timer_start; |
165 | ops->stop = nmi_timer_stop; |
166 | ops->cpu_type = "timer"; |
167 | |
168 | printk(KERN_INFO "oprofile: using NMI timer interrupt.\n"); |
169 | |
170 | return 0; |
171 | } |
172 | |
173 | #endif |
174 |
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