Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
[linux-2.6.git] / kernel / trace / trace_hw_branches.c
1 /*
2  * h/w branch tracer for x86 based on BTS
3  *
4  * Copyright (C) 2008-2009 Intel Corporation.
5  * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
6  */
7 #include <linux/kallsyms.h>
8 #include <linux/debugfs.h>
9 #include <linux/ftrace.h>
10 #include <linux/module.h>
11 #include <linux/cpu.h>
12 #include <linux/smp.h>
13 #include <linux/fs.h>
14
15 #include <asm/ds.h>
16
17 #include "trace_output.h"
18 #include "trace.h"
19
20
21 #define BTS_BUFFER_SIZE (1 << 13)
22
23 static DEFINE_PER_CPU(struct bts_tracer *, hwb_tracer);
24 static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], hwb_buffer);
25
26 #define this_tracer per_cpu(hwb_tracer, smp_processor_id())
27
28 static int trace_hw_branches_enabled __read_mostly;
29 static int trace_hw_branches_suspended __read_mostly;
30 static struct trace_array *hw_branch_trace __read_mostly;
31
32
33 static void bts_trace_init_cpu(int cpu)
34 {
35         per_cpu(hwb_tracer, cpu) =
36                 ds_request_bts_cpu(cpu, per_cpu(hwb_buffer, cpu),
37                                    BTS_BUFFER_SIZE, NULL, (size_t)-1,
38                                    BTS_KERNEL);
39
40         if (IS_ERR(per_cpu(hwb_tracer, cpu)))
41                 per_cpu(hwb_tracer, cpu) = NULL;
42 }
43
44 static int bts_trace_init(struct trace_array *tr)
45 {
46         int cpu;
47
48         hw_branch_trace = tr;
49         trace_hw_branches_enabled = 0;
50
51         get_online_cpus();
52         for_each_online_cpu(cpu) {
53                 bts_trace_init_cpu(cpu);
54
55                 if (likely(per_cpu(hwb_tracer, cpu)))
56                         trace_hw_branches_enabled = 1;
57         }
58         trace_hw_branches_suspended = 0;
59         put_online_cpus();
60
61         /* If we could not enable tracing on a single cpu, we fail. */
62         return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
63 }
64
65 static void bts_trace_reset(struct trace_array *tr)
66 {
67         int cpu;
68
69         get_online_cpus();
70         for_each_online_cpu(cpu) {
71                 if (likely(per_cpu(hwb_tracer, cpu))) {
72                         ds_release_bts(per_cpu(hwb_tracer, cpu));
73                         per_cpu(hwb_tracer, cpu) = NULL;
74                 }
75         }
76         trace_hw_branches_enabled = 0;
77         trace_hw_branches_suspended = 0;
78         put_online_cpus();
79 }
80
81 static void bts_trace_start(struct trace_array *tr)
82 {
83         int cpu;
84
85         get_online_cpus();
86         for_each_online_cpu(cpu)
87                 if (likely(per_cpu(hwb_tracer, cpu)))
88                         ds_resume_bts(per_cpu(hwb_tracer, cpu));
89         trace_hw_branches_suspended = 0;
90         put_online_cpus();
91 }
92
93 static void bts_trace_stop(struct trace_array *tr)
94 {
95         int cpu;
96
97         get_online_cpus();
98         for_each_online_cpu(cpu)
99                 if (likely(per_cpu(hwb_tracer, cpu)))
100                         ds_suspend_bts(per_cpu(hwb_tracer, cpu));
101         trace_hw_branches_suspended = 1;
102         put_online_cpus();
103 }
104
105 static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
106                                      unsigned long action, void *hcpu)
107 {
108         int cpu = (long)hcpu;
109
110         switch (action) {
111         case CPU_ONLINE:
112         case CPU_DOWN_FAILED:
113                 /* The notification is sent with interrupts enabled. */
114                 if (trace_hw_branches_enabled) {
115                         bts_trace_init_cpu(cpu);
116
117                         if (trace_hw_branches_suspended &&
118                             likely(per_cpu(hwb_tracer, cpu)))
119                                 ds_suspend_bts(per_cpu(hwb_tracer, cpu));
120                 }
121                 break;
122
123         case CPU_DOWN_PREPARE:
124                 /* The notification is sent with interrupts enabled. */
125                 if (likely(per_cpu(hwb_tracer, cpu))) {
126                         ds_release_bts(per_cpu(hwb_tracer, cpu));
127                         per_cpu(hwb_tracer, cpu) = NULL;
128                 }
129         }
130
131         return NOTIFY_DONE;
132 }
133
134 static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
135         .notifier_call = bts_hotcpu_handler
136 };
137
138 static void bts_trace_print_header(struct seq_file *m)
139 {
140         seq_puts(m, "# CPU#        TO  <-  FROM\n");
141 }
142
143 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
144 {
145         unsigned long symflags = TRACE_ITER_SYM_OFFSET;
146         struct trace_entry *entry = iter->ent;
147         struct trace_seq *seq = &iter->seq;
148         struct hw_branch_entry *it;
149
150         trace_assign_type(it, entry);
151
152         if (entry->type == TRACE_HW_BRANCHES) {
153                 if (trace_seq_printf(seq, "%4d  ", iter->cpu) &&
154                     seq_print_ip_sym(seq, it->to, symflags) &&
155                     trace_seq_printf(seq, "\t  <-  ") &&
156                     seq_print_ip_sym(seq, it->from, symflags) &&
157                     trace_seq_printf(seq, "\n"))
158                         return TRACE_TYPE_HANDLED;
159                 return TRACE_TYPE_PARTIAL_LINE;
160         }
161         return TRACE_TYPE_UNHANDLED;
162 }
163
164 void trace_hw_branch(u64 from, u64 to)
165 {
166         struct ftrace_event_call *call = &event_hw_branch;
167         struct trace_array *tr = hw_branch_trace;
168         struct ring_buffer_event *event;
169         struct ring_buffer *buf;
170         struct hw_branch_entry *entry;
171         unsigned long irq1;
172         int cpu;
173
174         if (unlikely(!tr))
175                 return;
176
177         if (unlikely(!trace_hw_branches_enabled))
178                 return;
179
180         local_irq_save(irq1);
181         cpu = raw_smp_processor_id();
182         if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
183                 goto out;
184
185         buf = tr->buffer;
186         event = trace_buffer_lock_reserve(buf, TRACE_HW_BRANCHES,
187                                           sizeof(*entry), 0, 0);
188         if (!event)
189                 goto out;
190         entry   = ring_buffer_event_data(event);
191         tracing_generic_entry_update(&entry->ent, 0, from);
192         entry->ent.type = TRACE_HW_BRANCHES;
193         entry->from = from;
194         entry->to   = to;
195         if (!filter_check_discard(call, entry, buf, event))
196                 trace_buffer_unlock_commit(buf, event, 0, 0);
197
198  out:
199         atomic_dec(&tr->data[cpu]->disabled);
200         local_irq_restore(irq1);
201 }
202
203 static void trace_bts_at(const struct bts_trace *trace, void *at)
204 {
205         struct bts_struct bts;
206         int err = 0;
207
208         WARN_ON_ONCE(!trace->read);
209         if (!trace->read)
210                 return;
211
212         err = trace->read(this_tracer, at, &bts);
213         if (err < 0)
214                 return;
215
216         switch (bts.qualifier) {
217         case BTS_BRANCH:
218                 trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
219                 break;
220         }
221 }
222
223 /*
224  * Collect the trace on the current cpu and write it into the ftrace buffer.
225  *
226  * pre: tracing must be suspended on the current cpu
227  */
228 static void trace_bts_cpu(void *arg)
229 {
230         struct trace_array *tr = (struct trace_array *)arg;
231         const struct bts_trace *trace;
232         unsigned char *at;
233
234         if (unlikely(!tr))
235                 return;
236
237         if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
238                 return;
239
240         if (unlikely(!this_tracer))
241                 return;
242
243         trace = ds_read_bts(this_tracer);
244         if (!trace)
245                 return;
246
247         for (at = trace->ds.top; (void *)at < trace->ds.end;
248              at += trace->ds.size)
249                 trace_bts_at(trace, at);
250
251         for (at = trace->ds.begin; (void *)at < trace->ds.top;
252              at += trace->ds.size)
253                 trace_bts_at(trace, at);
254 }
255
256 static void trace_bts_prepare(struct trace_iterator *iter)
257 {
258         int cpu;
259
260         get_online_cpus();
261         for_each_online_cpu(cpu)
262                 if (likely(per_cpu(hwb_tracer, cpu)))
263                         ds_suspend_bts(per_cpu(hwb_tracer, cpu));
264         /*
265          * We need to collect the trace on the respective cpu since ftrace
266          * implicitly adds the record for the current cpu.
267          * Once that is more flexible, we could collect the data from any cpu.
268          */
269         on_each_cpu(trace_bts_cpu, iter->tr, 1);
270
271         for_each_online_cpu(cpu)
272                 if (likely(per_cpu(hwb_tracer, cpu)))
273                         ds_resume_bts(per_cpu(hwb_tracer, cpu));
274         put_online_cpus();
275 }
276
277 static void trace_bts_close(struct trace_iterator *iter)
278 {
279         tracing_reset_online_cpus(iter->tr);
280 }
281
282 void trace_hw_branch_oops(void)
283 {
284         if (this_tracer) {
285                 ds_suspend_bts_noirq(this_tracer);
286                 trace_bts_cpu(hw_branch_trace);
287                 ds_resume_bts_noirq(this_tracer);
288         }
289 }
290
291 struct tracer bts_tracer __read_mostly =
292 {
293         .name           = "hw-branch-tracer",
294         .init           = bts_trace_init,
295         .reset          = bts_trace_reset,
296         .print_header   = bts_trace_print_header,
297         .print_line     = bts_trace_print_line,
298         .start          = bts_trace_start,
299         .stop           = bts_trace_stop,
300         .open           = trace_bts_prepare,
301         .close          = trace_bts_close,
302 #ifdef CONFIG_FTRACE_SELFTEST
303         .selftest       = trace_selftest_startup_hw_branches,
304 #endif /* CONFIG_FTRACE_SELFTEST */
305 };
306
307 __init static int init_bts_trace(void)
308 {
309         register_hotcpu_notifier(&bts_hotcpu_notifier);
310         return register_tracer(&bts_tracer);
311 }
312 device_initcall(init_bts_trace);