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Commit | Line | Data |
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1e9b51c2 | 1 | /* |
e9a22d1f | 2 | * h/w branch tracer for x86 based on BTS |
1e9b51c2 | 3 | * |
5c5317de MM |
4 | * Copyright (C) 2008-2009 Intel Corporation. |
5 | * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009 | |
1e9b51c2 | 6 | */ |
2d542cf3 | 7 | #include <linux/kallsyms.h> |
1e9b51c2 MM |
8 | #include <linux/debugfs.h> |
9 | #include <linux/ftrace.h> | |
2d542cf3 | 10 | #include <linux/module.h> |
5c5317de MM |
11 | #include <linux/cpu.h> |
12 | #include <linux/smp.h> | |
2d542cf3 | 13 | #include <linux/fs.h> |
1e9b51c2 MM |
14 | |
15 | #include <asm/ds.h> | |
16 | ||
f0868d1e | 17 | #include "trace_output.h" |
e9a22d1f | 18 | #include "trace.h" |
1e9b51c2 MM |
19 | |
20 | ||
ba9372a8 | 21 | #define BTS_BUFFER_SIZE (1 << 13) |
1e9b51c2 MM |
22 | |
23 | static DEFINE_PER_CPU(struct bts_tracer *, tracer); | |
ba9372a8 | 24 | static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer); |
1e9b51c2 MM |
25 | |
26 | #define this_tracer per_cpu(tracer, smp_processor_id()) | |
1e9b51c2 | 27 | |
ba9372a8 MM |
28 | static int trace_hw_branches_enabled __read_mostly; |
29 | static int trace_hw_branches_suspended __read_mostly; | |
b1818748 | 30 | static struct trace_array *hw_branch_trace __read_mostly; |
1e9b51c2 | 31 | |
5c5317de | 32 | |
de79f54f | 33 | static void bts_trace_init_cpu(int cpu) |
1e9b51c2 | 34 | { |
de79f54f MM |
35 | per_cpu(tracer, cpu) = |
36 | ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE, | |
37 | NULL, (size_t)-1, BTS_KERNEL); | |
a93751ca | 38 | |
de79f54f MM |
39 | if (IS_ERR(per_cpu(tracer, cpu))) |
40 | per_cpu(tracer, cpu) = NULL; | |
1e9b51c2 MM |
41 | } |
42 | ||
ba9372a8 | 43 | static int bts_trace_init(struct trace_array *tr) |
1e9b51c2 | 44 | { |
de79f54f | 45 | int cpu; |
1e9b51c2 | 46 | |
ba9372a8 | 47 | hw_branch_trace = tr; |
de79f54f | 48 | trace_hw_branches_enabled = 0; |
1e9b51c2 | 49 | |
de79f54f MM |
50 | get_online_cpus(); |
51 | for_each_online_cpu(cpu) { | |
52 | bts_trace_init_cpu(cpu); | |
1e9b51c2 | 53 | |
de79f54f MM |
54 | if (likely(per_cpu(tracer, cpu))) |
55 | trace_hw_branches_enabled = 1; | |
56 | } | |
ba9372a8 | 57 | trace_hw_branches_suspended = 0; |
de79f54f | 58 | put_online_cpus(); |
ba9372a8 MM |
59 | |
60 | /* If we could not enable tracing on a single cpu, we fail. */ | |
de79f54f | 61 | return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP; |
1e9b51c2 MM |
62 | } |
63 | ||
ba9372a8 | 64 | static void bts_trace_reset(struct trace_array *tr) |
1e9b51c2 | 65 | { |
de79f54f | 66 | int cpu; |
5c5317de | 67 | |
de79f54f MM |
68 | get_online_cpus(); |
69 | for_each_online_cpu(cpu) { | |
70 | if (likely(per_cpu(tracer, cpu))) { | |
71 | ds_release_bts(per_cpu(tracer, cpu)); | |
72 | per_cpu(tracer, cpu) = NULL; | |
73 | } | |
1e9b51c2 | 74 | } |
5c5317de | 75 | trace_hw_branches_enabled = 0; |
ba9372a8 | 76 | trace_hw_branches_suspended = 0; |
de79f54f | 77 | put_online_cpus(); |
1e9b51c2 MM |
78 | } |
79 | ||
ba9372a8 | 80 | static void bts_trace_start(struct trace_array *tr) |
1e9b51c2 | 81 | { |
de79f54f | 82 | int cpu; |
5c5317de | 83 | |
de79f54f MM |
84 | get_online_cpus(); |
85 | for_each_online_cpu(cpu) | |
86 | if (likely(per_cpu(tracer, cpu))) | |
87 | ds_resume_bts(per_cpu(tracer, cpu)); | |
ba9372a8 | 88 | trace_hw_branches_suspended = 0; |
de79f54f | 89 | put_online_cpus(); |
ba9372a8 | 90 | } |
1e9b51c2 | 91 | |
ba9372a8 MM |
92 | static void bts_trace_stop(struct trace_array *tr) |
93 | { | |
de79f54f | 94 | int cpu; |
ba9372a8 | 95 | |
de79f54f MM |
96 | get_online_cpus(); |
97 | for_each_online_cpu(cpu) | |
98 | if (likely(per_cpu(tracer, cpu))) | |
99 | ds_suspend_bts(per_cpu(tracer, cpu)); | |
ba9372a8 | 100 | trace_hw_branches_suspended = 1; |
de79f54f | 101 | put_online_cpus(); |
5c5317de MM |
102 | } |
103 | ||
104 | static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb, | |
105 | unsigned long action, void *hcpu) | |
106 | { | |
de79f54f | 107 | int cpu = (long)hcpu; |
5c5317de MM |
108 | |
109 | switch (action) { | |
110 | case CPU_ONLINE: | |
111 | case CPU_DOWN_FAILED: | |
de79f54f MM |
112 | /* The notification is sent with interrupts enabled. */ |
113 | if (trace_hw_branches_enabled) { | |
114 | bts_trace_init_cpu(cpu); | |
115 | ||
116 | if (trace_hw_branches_suspended && | |
117 | likely(per_cpu(tracer, cpu))) | |
118 | ds_suspend_bts(per_cpu(tracer, cpu)); | |
119 | } | |
5c5317de | 120 | break; |
de79f54f | 121 | |
5c5317de | 122 | case CPU_DOWN_PREPARE: |
de79f54f MM |
123 | /* The notification is sent with interrupts enabled. */ |
124 | if (likely(per_cpu(tracer, cpu))) { | |
125 | ds_release_bts(per_cpu(tracer, cpu)); | |
126 | per_cpu(tracer, cpu) = NULL; | |
127 | } | |
5c5317de MM |
128 | } |
129 | ||
5c5317de | 130 | return NOTIFY_DONE; |
1e9b51c2 MM |
131 | } |
132 | ||
5c5317de MM |
133 | static struct notifier_block bts_hotcpu_notifier __cpuinitdata = { |
134 | .notifier_call = bts_hotcpu_handler | |
135 | }; | |
136 | ||
1e9b51c2 MM |
137 | static void bts_trace_print_header(struct seq_file *m) |
138 | { | |
11edda06 | 139 | seq_puts(m, "# CPU# TO <- FROM\n"); |
1e9b51c2 MM |
140 | } |
141 | ||
142 | static enum print_line_t bts_trace_print_line(struct trace_iterator *iter) | |
143 | { | |
e9a22d1f | 144 | unsigned long symflags = TRACE_ITER_SYM_OFFSET; |
1e9b51c2 MM |
145 | struct trace_entry *entry = iter->ent; |
146 | struct trace_seq *seq = &iter->seq; | |
a93751ca | 147 | struct hw_branch_entry *it; |
1e9b51c2 MM |
148 | |
149 | trace_assign_type(it, entry); | |
150 | ||
a93751ca | 151 | if (entry->type == TRACE_HW_BRANCHES) { |
1830b52d | 152 | if (trace_seq_printf(seq, "%4d ", iter->cpu) && |
11edda06 MM |
153 | seq_print_ip_sym(seq, it->to, symflags) && |
154 | trace_seq_printf(seq, "\t <- ") && | |
155 | seq_print_ip_sym(seq, it->from, symflags) && | |
a93751ca MM |
156 | trace_seq_printf(seq, "\n")) |
157 | return TRACE_TYPE_HANDLED; | |
158 | return TRACE_TYPE_PARTIAL_LINE;; | |
1e9b51c2 MM |
159 | } |
160 | return TRACE_TYPE_UNHANDLED; | |
161 | } | |
162 | ||
b1818748 | 163 | void trace_hw_branch(u64 from, u64 to) |
1e9b51c2 | 164 | { |
e1112b4d | 165 | struct ftrace_event_call *call = &event_hw_branch; |
b1818748 | 166 | struct trace_array *tr = hw_branch_trace; |
1e9b51c2 | 167 | struct ring_buffer_event *event; |
a93751ca | 168 | struct hw_branch_entry *entry; |
0a987751 | 169 | unsigned long irq1; |
5c5317de | 170 | int cpu; |
1e9b51c2 | 171 | |
5c5317de MM |
172 | if (unlikely(!tr)) |
173 | return; | |
174 | ||
175 | if (unlikely(!trace_hw_branches_enabled)) | |
1e9b51c2 | 176 | return; |
5c5317de MM |
177 | |
178 | local_irq_save(irq1); | |
179 | cpu = raw_smp_processor_id(); | |
180 | if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) | |
181 | goto out; | |
182 | ||
51a763dd ACM |
183 | event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES, |
184 | sizeof(*entry), 0, 0); | |
5c5317de MM |
185 | if (!event) |
186 | goto out; | |
1e9b51c2 MM |
187 | entry = ring_buffer_event_data(event); |
188 | tracing_generic_entry_update(&entry->ent, 0, from); | |
a93751ca | 189 | entry->ent.type = TRACE_HW_BRANCHES; |
1e9b51c2 MM |
190 | entry->from = from; |
191 | entry->to = to; | |
eb02ce01 TZ |
192 | if (!filter_check_discard(call, entry, tr->buffer, event)) |
193 | trace_buffer_unlock_commit(tr, event, 0, 0); | |
5c5317de MM |
194 | |
195 | out: | |
196 | atomic_dec(&tr->data[cpu]->disabled); | |
197 | local_irq_restore(irq1); | |
1e9b51c2 MM |
198 | } |
199 | ||
b1818748 | 200 | static void trace_bts_at(const struct bts_trace *trace, void *at) |
1e9b51c2 | 201 | { |
a93751ca MM |
202 | struct bts_struct bts; |
203 | int err = 0; | |
1e9b51c2 | 204 | |
a93751ca MM |
205 | WARN_ON_ONCE(!trace->read); |
206 | if (!trace->read) | |
1e9b51c2 MM |
207 | return; |
208 | ||
a93751ca MM |
209 | err = trace->read(this_tracer, at, &bts); |
210 | if (err < 0) | |
211 | return; | |
1e9b51c2 | 212 | |
a93751ca MM |
213 | switch (bts.qualifier) { |
214 | case BTS_BRANCH: | |
b1818748 | 215 | trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to); |
a93751ca MM |
216 | break; |
217 | } | |
1e9b51c2 MM |
218 | } |
219 | ||
5c5317de MM |
220 | /* |
221 | * Collect the trace on the current cpu and write it into the ftrace buffer. | |
222 | * | |
de79f54f | 223 | * pre: tracing must be suspended on the current cpu |
5c5317de | 224 | */ |
1e9b51c2 MM |
225 | static void trace_bts_cpu(void *arg) |
226 | { | |
ba9372a8 | 227 | struct trace_array *tr = (struct trace_array *)arg; |
a93751ca MM |
228 | const struct bts_trace *trace; |
229 | unsigned char *at; | |
1e9b51c2 | 230 | |
b1818748 | 231 | if (unlikely(!tr)) |
1e9b51c2 MM |
232 | return; |
233 | ||
5c5317de MM |
234 | if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled))) |
235 | return; | |
236 | ||
b1818748 MM |
237 | if (unlikely(!this_tracer)) |
238 | return; | |
239 | ||
a93751ca MM |
240 | trace = ds_read_bts(this_tracer); |
241 | if (!trace) | |
de79f54f | 242 | return; |
1e9b51c2 | 243 | |
a93751ca MM |
244 | for (at = trace->ds.top; (void *)at < trace->ds.end; |
245 | at += trace->ds.size) | |
b1818748 | 246 | trace_bts_at(trace, at); |
1e9b51c2 | 247 | |
a93751ca MM |
248 | for (at = trace->ds.begin; (void *)at < trace->ds.top; |
249 | at += trace->ds.size) | |
b1818748 | 250 | trace_bts_at(trace, at); |
1e9b51c2 MM |
251 | } |
252 | ||
253 | static void trace_bts_prepare(struct trace_iterator *iter) | |
254 | { | |
de79f54f | 255 | int cpu; |
5c5317de | 256 | |
de79f54f MM |
257 | get_online_cpus(); |
258 | for_each_online_cpu(cpu) | |
259 | if (likely(per_cpu(tracer, cpu))) | |
260 | ds_suspend_bts(per_cpu(tracer, cpu)); | |
261 | /* | |
262 | * We need to collect the trace on the respective cpu since ftrace | |
263 | * implicitly adds the record for the current cpu. | |
264 | * Once that is more flexible, we could collect the data from any cpu. | |
265 | */ | |
5c5317de | 266 | on_each_cpu(trace_bts_cpu, iter->tr, 1); |
1e9b51c2 | 267 | |
de79f54f MM |
268 | for_each_online_cpu(cpu) |
269 | if (likely(per_cpu(tracer, cpu))) | |
270 | ds_resume_bts(per_cpu(tracer, cpu)); | |
271 | put_online_cpus(); | |
1e9b51c2 MM |
272 | } |
273 | ||
e23b8ad8 MM |
274 | static void trace_bts_close(struct trace_iterator *iter) |
275 | { | |
276 | tracing_reset_online_cpus(iter->tr); | |
277 | } | |
278 | ||
b1818748 MM |
279 | void trace_hw_branch_oops(void) |
280 | { | |
de79f54f MM |
281 | if (this_tracer) { |
282 | ds_suspend_bts_noirq(this_tracer); | |
ba9372a8 | 283 | trace_bts_cpu(hw_branch_trace); |
de79f54f MM |
284 | ds_resume_bts_noirq(this_tracer); |
285 | } | |
b1818748 MM |
286 | } |
287 | ||
1e9b51c2 MM |
288 | struct tracer bts_tracer __read_mostly = |
289 | { | |
a93751ca | 290 | .name = "hw-branch-tracer", |
1e9b51c2 | 291 | .init = bts_trace_init, |
5c5317de | 292 | .reset = bts_trace_reset, |
1e9b51c2 MM |
293 | .print_header = bts_trace_print_header, |
294 | .print_line = bts_trace_print_line, | |
295 | .start = bts_trace_start, | |
296 | .stop = bts_trace_stop, | |
e23b8ad8 | 297 | .open = trace_bts_prepare, |
321bb5e1 MM |
298 | .close = trace_bts_close, |
299 | #ifdef CONFIG_FTRACE_SELFTEST | |
300 | .selftest = trace_selftest_startup_hw_branches, | |
301 | #endif /* CONFIG_FTRACE_SELFTEST */ | |
1e9b51c2 MM |
302 | }; |
303 | ||
304 | __init static int init_bts_trace(void) | |
305 | { | |
5e01cb69 | 306 | register_hotcpu_notifier(&bts_hotcpu_notifier); |
1e9b51c2 MM |
307 | return register_tracer(&bts_tracer); |
308 | } | |
309 | device_initcall(init_bts_trace); |