Commit | Line | Data |
---|---|---|
1e9b51c2 | 1 | /* |
a93751ca | 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 IM |
7 | #include <linux/spinlock.h> |
8 | #include <linux/kallsyms.h> | |
1e9b51c2 MM |
9 | #include <linux/debugfs.h> |
10 | #include <linux/ftrace.h> | |
2d542cf3 | 11 | #include <linux/module.h> |
5c5317de MM |
12 | #include <linux/cpu.h> |
13 | #include <linux/smp.h> | |
2d542cf3 | 14 | #include <linux/fs.h> |
1e9b51c2 MM |
15 | |
16 | #include <asm/ds.h> | |
17 | ||
18 | #include "trace.h" | |
f0868d1e | 19 | #include "trace_output.h" |
1e9b51c2 MM |
20 | |
21 | ||
22 | #define SIZEOF_BTS (1 << 13) | |
23 | ||
2d542cf3 IM |
24 | /* |
25 | * The tracer lock protects the below per-cpu tracer array. | |
26 | * It needs to be held to: | |
27 | * - start tracing on all cpus | |
28 | * - stop tracing on all cpus | |
29 | * - start tracing on a single hotplug cpu | |
30 | * - stop tracing on a single hotplug cpu | |
31 | * - read the trace from all cpus | |
32 | * - read the trace from a single cpu | |
33 | */ | |
34 | static DEFINE_SPINLOCK(bts_tracer_lock); | |
1e9b51c2 MM |
35 | static DEFINE_PER_CPU(struct bts_tracer *, tracer); |
36 | static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer); | |
37 | ||
38 | #define this_tracer per_cpu(tracer, smp_processor_id()) | |
39 | #define this_buffer per_cpu(buffer, smp_processor_id()) | |
40 | ||
5c5317de | 41 | static int __read_mostly trace_hw_branches_enabled; |
b1818748 | 42 | static struct trace_array *hw_branch_trace __read_mostly; |
1e9b51c2 | 43 | |
5c5317de MM |
44 | |
45 | /* | |
46 | * Start tracing on the current cpu. | |
47 | * The argument is ignored. | |
48 | * | |
2d542cf3 | 49 | * pre: bts_tracer_lock must be locked. |
5c5317de | 50 | */ |
1e9b51c2 MM |
51 | static void bts_trace_start_cpu(void *arg) |
52 | { | |
a93751ca MM |
53 | if (this_tracer) |
54 | ds_release_bts(this_tracer); | |
55 | ||
1e9b51c2 MM |
56 | this_tracer = |
57 | ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS, | |
a93751ca MM |
58 | /* ovfl = */ NULL, /* th = */ (size_t)-1, |
59 | BTS_KERNEL); | |
1e9b51c2 MM |
60 | if (IS_ERR(this_tracer)) { |
61 | this_tracer = NULL; | |
62 | return; | |
63 | } | |
1e9b51c2 MM |
64 | } |
65 | ||
66 | static void bts_trace_start(struct trace_array *tr) | |
67 | { | |
2d542cf3 | 68 | spin_lock(&bts_tracer_lock); |
1e9b51c2 | 69 | |
5c5317de MM |
70 | on_each_cpu(bts_trace_start_cpu, NULL, 1); |
71 | trace_hw_branches_enabled = 1; | |
1e9b51c2 | 72 | |
2d542cf3 | 73 | spin_unlock(&bts_tracer_lock); |
1e9b51c2 MM |
74 | } |
75 | ||
5c5317de | 76 | /* |
c3706f00 | 77 | * Stop tracing on the current cpu. |
5c5317de MM |
78 | * The argument is ignored. |
79 | * | |
2d542cf3 | 80 | * pre: bts_tracer_lock must be locked. |
5c5317de | 81 | */ |
1e9b51c2 MM |
82 | static void bts_trace_stop_cpu(void *arg) |
83 | { | |
84 | if (this_tracer) { | |
1e9b51c2 MM |
85 | ds_release_bts(this_tracer); |
86 | this_tracer = NULL; | |
87 | } | |
88 | } | |
89 | ||
90 | static void bts_trace_stop(struct trace_array *tr) | |
91 | { | |
2d542cf3 | 92 | spin_lock(&bts_tracer_lock); |
5c5317de MM |
93 | |
94 | trace_hw_branches_enabled = 0; | |
95 | on_each_cpu(bts_trace_stop_cpu, NULL, 1); | |
1e9b51c2 | 96 | |
2d542cf3 | 97 | spin_unlock(&bts_tracer_lock); |
5c5317de MM |
98 | } |
99 | ||
100 | static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb, | |
101 | unsigned long action, void *hcpu) | |
102 | { | |
103 | unsigned int cpu = (unsigned long)hcpu; | |
104 | ||
2d542cf3 | 105 | spin_lock(&bts_tracer_lock); |
5c5317de MM |
106 | |
107 | if (!trace_hw_branches_enabled) | |
108 | goto out; | |
109 | ||
110 | switch (action) { | |
111 | case CPU_ONLINE: | |
112 | case CPU_DOWN_FAILED: | |
113 | smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1); | |
114 | break; | |
115 | case CPU_DOWN_PREPARE: | |
1e9b51c2 | 116 | smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1); |
5c5317de MM |
117 | break; |
118 | } | |
119 | ||
120 | out: | |
2d542cf3 | 121 | spin_unlock(&bts_tracer_lock); |
5c5317de | 122 | return NOTIFY_DONE; |
1e9b51c2 MM |
123 | } |
124 | ||
5c5317de MM |
125 | static struct notifier_block bts_hotcpu_notifier __cpuinitdata = { |
126 | .notifier_call = bts_hotcpu_handler | |
127 | }; | |
128 | ||
5e01cb69 | 129 | static int bts_trace_init(struct trace_array *tr) |
1e9b51c2 | 130 | { |
b1818748 MM |
131 | hw_branch_trace = tr; |
132 | ||
1e9b51c2 MM |
133 | bts_trace_start(tr); |
134 | ||
135 | return 0; | |
136 | } | |
137 | ||
5e01cb69 | 138 | static void bts_trace_reset(struct trace_array *tr) |
5c5317de MM |
139 | { |
140 | bts_trace_stop(tr); | |
5c5317de MM |
141 | } |
142 | ||
1e9b51c2 MM |
143 | static void bts_trace_print_header(struct seq_file *m) |
144 | { | |
11edda06 | 145 | seq_puts(m, "# CPU# TO <- FROM\n"); |
1e9b51c2 MM |
146 | } |
147 | ||
148 | static enum print_line_t bts_trace_print_line(struct trace_iterator *iter) | |
149 | { | |
150 | struct trace_entry *entry = iter->ent; | |
151 | struct trace_seq *seq = &iter->seq; | |
a93751ca | 152 | struct hw_branch_entry *it; |
11edda06 | 153 | unsigned long symflags = TRACE_ITER_SYM_OFFSET; |
1e9b51c2 MM |
154 | |
155 | trace_assign_type(it, entry); | |
156 | ||
a93751ca | 157 | if (entry->type == TRACE_HW_BRANCHES) { |
1830b52d | 158 | if (trace_seq_printf(seq, "%4d ", iter->cpu) && |
11edda06 MM |
159 | seq_print_ip_sym(seq, it->to, symflags) && |
160 | trace_seq_printf(seq, "\t <- ") && | |
161 | seq_print_ip_sym(seq, it->from, symflags) && | |
a93751ca MM |
162 | trace_seq_printf(seq, "\n")) |
163 | return TRACE_TYPE_HANDLED; | |
164 | return TRACE_TYPE_PARTIAL_LINE;; | |
1e9b51c2 MM |
165 | } |
166 | return TRACE_TYPE_UNHANDLED; | |
167 | } | |
168 | ||
b1818748 | 169 | void trace_hw_branch(u64 from, u64 to) |
1e9b51c2 | 170 | { |
b1818748 | 171 | struct trace_array *tr = hw_branch_trace; |
1e9b51c2 | 172 | struct ring_buffer_event *event; |
a93751ca | 173 | struct hw_branch_entry *entry; |
0a987751 | 174 | unsigned long irq1; |
5c5317de | 175 | int cpu; |
1e9b51c2 | 176 | |
5c5317de MM |
177 | if (unlikely(!tr)) |
178 | return; | |
179 | ||
180 | if (unlikely(!trace_hw_branches_enabled)) | |
1e9b51c2 | 181 | return; |
5c5317de MM |
182 | |
183 | local_irq_save(irq1); | |
184 | cpu = raw_smp_processor_id(); | |
185 | if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) | |
186 | goto out; | |
187 | ||
51a763dd ACM |
188 | event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES, |
189 | sizeof(*entry), 0, 0); | |
5c5317de MM |
190 | if (!event) |
191 | goto out; | |
1e9b51c2 MM |
192 | entry = ring_buffer_event_data(event); |
193 | tracing_generic_entry_update(&entry->ent, 0, from); | |
a93751ca | 194 | entry->ent.type = TRACE_HW_BRANCHES; |
1e9b51c2 MM |
195 | entry->from = from; |
196 | entry->to = to; | |
51a763dd | 197 | trace_buffer_unlock_commit(tr, event, 0, 0); |
5c5317de MM |
198 | |
199 | out: | |
200 | atomic_dec(&tr->data[cpu]->disabled); | |
201 | local_irq_restore(irq1); | |
1e9b51c2 MM |
202 | } |
203 | ||
b1818748 | 204 | static void trace_bts_at(const struct bts_trace *trace, void *at) |
1e9b51c2 | 205 | { |
a93751ca MM |
206 | struct bts_struct bts; |
207 | int err = 0; | |
1e9b51c2 | 208 | |
a93751ca MM |
209 | WARN_ON_ONCE(!trace->read); |
210 | if (!trace->read) | |
1e9b51c2 MM |
211 | return; |
212 | ||
a93751ca MM |
213 | err = trace->read(this_tracer, at, &bts); |
214 | if (err < 0) | |
215 | return; | |
1e9b51c2 | 216 | |
a93751ca MM |
217 | switch (bts.qualifier) { |
218 | case BTS_BRANCH: | |
b1818748 | 219 | trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to); |
a93751ca MM |
220 | break; |
221 | } | |
1e9b51c2 MM |
222 | } |
223 | ||
5c5317de MM |
224 | /* |
225 | * Collect the trace on the current cpu and write it into the ftrace buffer. | |
226 | * | |
2d542cf3 | 227 | * pre: bts_tracer_lock must be locked |
5c5317de | 228 | */ |
1e9b51c2 MM |
229 | static void trace_bts_cpu(void *arg) |
230 | { | |
231 | struct trace_array *tr = (struct trace_array *) arg; | |
a93751ca MM |
232 | const struct bts_trace *trace; |
233 | unsigned char *at; | |
1e9b51c2 | 234 | |
b1818748 | 235 | if (unlikely(!tr)) |
1e9b51c2 MM |
236 | return; |
237 | ||
5c5317de MM |
238 | if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled))) |
239 | return; | |
240 | ||
b1818748 MM |
241 | if (unlikely(!this_tracer)) |
242 | return; | |
243 | ||
a93751ca MM |
244 | ds_suspend_bts(this_tracer); |
245 | trace = ds_read_bts(this_tracer); | |
246 | if (!trace) | |
1e9b51c2 MM |
247 | goto out; |
248 | ||
a93751ca MM |
249 | for (at = trace->ds.top; (void *)at < trace->ds.end; |
250 | at += trace->ds.size) | |
b1818748 | 251 | trace_bts_at(trace, at); |
1e9b51c2 | 252 | |
a93751ca MM |
253 | for (at = trace->ds.begin; (void *)at < trace->ds.top; |
254 | at += trace->ds.size) | |
b1818748 | 255 | trace_bts_at(trace, at); |
1e9b51c2 MM |
256 | |
257 | out: | |
a93751ca | 258 | ds_resume_bts(this_tracer); |
1e9b51c2 MM |
259 | } |
260 | ||
261 | static void trace_bts_prepare(struct trace_iterator *iter) | |
262 | { | |
2d542cf3 | 263 | spin_lock(&bts_tracer_lock); |
5c5317de MM |
264 | |
265 | on_each_cpu(trace_bts_cpu, iter->tr, 1); | |
1e9b51c2 | 266 | |
2d542cf3 | 267 | spin_unlock(&bts_tracer_lock); |
1e9b51c2 MM |
268 | } |
269 | ||
e23b8ad8 MM |
270 | static void trace_bts_close(struct trace_iterator *iter) |
271 | { | |
272 | tracing_reset_online_cpus(iter->tr); | |
273 | } | |
274 | ||
b1818748 MM |
275 | void trace_hw_branch_oops(void) |
276 | { | |
2d542cf3 | 277 | spin_lock(&bts_tracer_lock); |
b1818748 MM |
278 | |
279 | trace_bts_cpu(hw_branch_trace); | |
280 | ||
2d542cf3 | 281 | spin_unlock(&bts_tracer_lock); |
b1818748 MM |
282 | } |
283 | ||
1e9b51c2 MM |
284 | struct tracer bts_tracer __read_mostly = |
285 | { | |
a93751ca | 286 | .name = "hw-branch-tracer", |
1e9b51c2 | 287 | .init = bts_trace_init, |
5c5317de | 288 | .reset = bts_trace_reset, |
1e9b51c2 MM |
289 | .print_header = bts_trace_print_header, |
290 | .print_line = bts_trace_print_line, | |
291 | .start = bts_trace_start, | |
292 | .stop = bts_trace_stop, | |
e23b8ad8 MM |
293 | .open = trace_bts_prepare, |
294 | .close = trace_bts_close | |
1e9b51c2 MM |
295 | }; |
296 | ||
297 | __init static int init_bts_trace(void) | |
298 | { | |
5e01cb69 | 299 | register_hotcpu_notifier(&bts_hotcpu_notifier); |
1e9b51c2 MM |
300 | return register_tracer(&bts_tracer); |
301 | } | |
302 | device_initcall(init_bts_trace); |