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dcfce4a0 RR |
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 |