Commit | Line | Data |
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0722db01 P |
1 | /* |
2 | * trace_ksym.c - Kernel Symbol Tracer | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2009 | |
19 | */ | |
20 | ||
21 | #include <linux/kallsyms.h> | |
22 | #include <linux/uaccess.h> | |
23 | #include <linux/debugfs.h> | |
24 | #include <linux/ftrace.h> | |
25 | #include <linux/module.h> | |
26 | #include <linux/fs.h> | |
27 | ||
28 | #include "trace_output.h" | |
29 | #include "trace_stat.h" | |
30 | #include "trace.h" | |
31 | ||
24f1e32c FW |
32 | #include <linux/hw_breakpoint.h> |
33 | #include <asm/hw_breakpoint.h> | |
34 | ||
35 | /* | |
36 | * For now, let us restrict the no. of symbols traced simultaneously to number | |
0722db01 P |
37 | * of available hardware breakpoint registers. |
38 | */ | |
39 | #define KSYM_TRACER_MAX HBP_NUM | |
40 | ||
41 | #define KSYM_TRACER_OP_LEN 3 /* rw- */ | |
0722db01 | 42 | |
db59504d | 43 | struct trace_ksym { |
24f1e32c | 44 | struct perf_event **ksym_hbp; |
db59504d | 45 | unsigned long ksym_addr; |
24f1e32c FW |
46 | int type; |
47 | int len; | |
db59504d LZ |
48 | #ifdef CONFIG_PROFILE_KSYM_TRACER |
49 | unsigned long counter; | |
50 | #endif | |
51 | struct hlist_node ksym_hlist; | |
52 | }; | |
53 | ||
0722db01 P |
54 | static struct trace_array *ksym_trace_array; |
55 | ||
56 | static unsigned int ksym_filter_entry_count; | |
57 | static unsigned int ksym_tracing_enabled; | |
58 | ||
59 | static HLIST_HEAD(ksym_filter_head); | |
60 | ||
73874005 FW |
61 | static DEFINE_MUTEX(ksym_tracer_mutex); |
62 | ||
0722db01 P |
63 | #ifdef CONFIG_PROFILE_KSYM_TRACER |
64 | ||
65 | #define MAX_UL_INT 0xffffffff | |
66 | ||
0722db01 P |
67 | void ksym_collect_stats(unsigned long hbp_hit_addr) |
68 | { | |
69 | struct hlist_node *node; | |
70 | struct trace_ksym *entry; | |
71 | ||
72 | rcu_read_lock(); | |
73 | hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) { | |
74 | if ((entry->ksym_addr == hbp_hit_addr) && | |
75 | (entry->counter <= MAX_UL_INT)) { | |
76 | entry->counter++; | |
77 | break; | |
78 | } | |
79 | } | |
80 | rcu_read_unlock(); | |
81 | } | |
82 | #endif /* CONFIG_PROFILE_KSYM_TRACER */ | |
83 | ||
24f1e32c | 84 | void ksym_hbp_handler(struct perf_event *hbp, void *data) |
0722db01 P |
85 | { |
86 | struct ring_buffer_event *event; | |
db59504d | 87 | struct ksym_trace_entry *entry; |
24f1e32c | 88 | struct pt_regs *regs = data; |
d6a65dff | 89 | struct ring_buffer *buffer; |
0722db01 P |
90 | int pc; |
91 | ||
92 | if (!ksym_tracing_enabled) | |
93 | return; | |
94 | ||
d6a65dff FW |
95 | buffer = ksym_trace_array->buffer; |
96 | ||
0722db01 P |
97 | pc = preempt_count(); |
98 | ||
d6a65dff | 99 | event = trace_buffer_lock_reserve(buffer, TRACE_KSYM, |
0722db01 P |
100 | sizeof(*entry), 0, pc); |
101 | if (!event) | |
102 | return; | |
103 | ||
db59504d LZ |
104 | entry = ring_buffer_event_data(event); |
105 | entry->ip = instruction_pointer(regs); | |
24f1e32c FW |
106 | entry->type = hw_breakpoint_type(hbp); |
107 | entry->addr = hw_breakpoint_addr(hbp); | |
db59504d LZ |
108 | strlcpy(entry->cmd, current->comm, TASK_COMM_LEN); |
109 | ||
0722db01 | 110 | #ifdef CONFIG_PROFILE_KSYM_TRACER |
24f1e32c | 111 | ksym_collect_stats(hw_breakpoint_addr(hbp)); |
0722db01 P |
112 | #endif /* CONFIG_PROFILE_KSYM_TRACER */ |
113 | ||
d6a65dff | 114 | trace_buffer_unlock_commit(buffer, event, 0, pc); |
0722db01 P |
115 | } |
116 | ||
117 | /* Valid access types are represented as | |
118 | * | |
119 | * rw- : Set Read/Write Access Breakpoint | |
120 | * -w- : Set Write Access Breakpoint | |
121 | * --- : Clear Breakpoints | |
122 | * --x : Set Execution Break points (Not available yet) | |
123 | * | |
124 | */ | |
f088e547 | 125 | static int ksym_trace_get_access_type(char *str) |
0722db01 | 126 | { |
f088e547 | 127 | int access = 0; |
0722db01 | 128 | |
f088e547 | 129 | if (str[0] == 'r') |
24f1e32c | 130 | access |= HW_BREAKPOINT_R; |
f088e547 LZ |
131 | |
132 | if (str[1] == 'w') | |
24f1e32c | 133 | access |= HW_BREAKPOINT_W; |
f088e547 | 134 | |
24f1e32c FW |
135 | if (str[2] == 'x') |
136 | access |= HW_BREAKPOINT_X; | |
0722db01 P |
137 | |
138 | switch (access) { | |
24f1e32c FW |
139 | case HW_BREAKPOINT_W: |
140 | case HW_BREAKPOINT_W | HW_BREAKPOINT_R: | |
141 | return access; | |
142 | default: | |
143 | return -EINVAL; | |
0722db01 | 144 | } |
0722db01 P |
145 | } |
146 | ||
147 | /* | |
148 | * There can be several possible malformed requests and we attempt to capture | |
149 | * all of them. We enumerate some of the rules | |
150 | * 1. We will not allow kernel symbols with ':' since it is used as a delimiter. | |
151 | * i.e. multiple ':' symbols disallowed. Possible uses are of the form | |
152 | * <module>:<ksym_name>:<op>. | |
153 | * 2. No delimiter symbol ':' in the input string | |
154 | * 3. Spurious operator symbols or symbols not in their respective positions | |
155 | * 4. <ksym_name>:--- i.e. clear breakpoint request when ksym_name not in file | |
156 | * 5. Kernel symbol not a part of /proc/kallsyms | |
157 | * 6. Duplicate requests | |
158 | */ | |
159 | static int parse_ksym_trace_str(char *input_string, char **ksymname, | |
160 | unsigned long *addr) | |
161 | { | |
0722db01 P |
162 | int ret; |
163 | ||
92cf9f8f | 164 | *ksymname = strsep(&input_string, ":"); |
0722db01 P |
165 | *addr = kallsyms_lookup_name(*ksymname); |
166 | ||
167 | /* Check for malformed request: (2), (1) and (5) */ | |
168 | if ((!input_string) || | |
92cf9f8f LZ |
169 | (strlen(input_string) != KSYM_TRACER_OP_LEN) || |
170 | (*addr == 0)) | |
171 | return -EINVAL;; | |
172 | ||
0722db01 P |
173 | ret = ksym_trace_get_access_type(input_string); |
174 | ||
0722db01 P |
175 | return ret; |
176 | } | |
177 | ||
178 | int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) | |
179 | { | |
180 | struct trace_ksym *entry; | |
558df6c8 | 181 | int ret = -ENOMEM; |
0722db01 P |
182 | |
183 | if (ksym_filter_entry_count >= KSYM_TRACER_MAX) { | |
184 | printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No" | |
185 | " new requests for tracing can be accepted now.\n", | |
186 | KSYM_TRACER_MAX); | |
187 | return -ENOSPC; | |
188 | } | |
189 | ||
190 | entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL); | |
191 | if (!entry) | |
192 | return -ENOMEM; | |
193 | ||
24f1e32c FW |
194 | entry->type = op; |
195 | entry->ksym_addr = addr; | |
196 | entry->len = HW_BREAKPOINT_LEN_4; | |
197 | ||
198 | ret = -EAGAIN; | |
199 | entry->ksym_hbp = register_wide_hw_breakpoint(entry->ksym_addr, | |
200 | entry->len, entry->type, | |
201 | ksym_hbp_handler, true); | |
202 | if (IS_ERR(entry->ksym_hbp)) { | |
203 | entry->ksym_hbp = NULL; | |
204 | ret = PTR_ERR(entry->ksym_hbp); | |
205 | } | |
0722db01 | 206 | |
24f1e32c | 207 | if (!entry->ksym_hbp) { |
0722db01 P |
208 | printk(KERN_INFO "ksym_tracer request failed. Try again" |
209 | " later!!\n"); | |
558df6c8 | 210 | goto err; |
0722db01 | 211 | } |
24f1e32c | 212 | |
0722db01 P |
213 | hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head); |
214 | ksym_filter_entry_count++; | |
24f1e32c | 215 | |
0722db01 | 216 | return 0; |
24f1e32c | 217 | |
558df6c8 | 218 | err: |
558df6c8 | 219 | kfree(entry); |
24f1e32c | 220 | |
558df6c8 | 221 | return ret; |
0722db01 P |
222 | } |
223 | ||
224 | static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf, | |
225 | size_t count, loff_t *ppos) | |
226 | { | |
227 | struct trace_ksym *entry; | |
228 | struct hlist_node *node; | |
be9742e6 LZ |
229 | struct trace_seq *s; |
230 | ssize_t cnt = 0; | |
231 | int ret; | |
232 | ||
233 | s = kmalloc(sizeof(*s), GFP_KERNEL); | |
234 | if (!s) | |
235 | return -ENOMEM; | |
236 | trace_seq_init(s); | |
0722db01 P |
237 | |
238 | mutex_lock(&ksym_tracer_mutex); | |
239 | ||
240 | hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { | |
24f1e32c FW |
241 | ret = trace_seq_printf(s, "%pS:", (void *)entry->ksym_addr); |
242 | if (entry->type == HW_BREAKPOINT_W) | |
be9742e6 | 243 | ret = trace_seq_puts(s, "-w-\n"); |
24f1e32c | 244 | else if (entry->type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R)) |
be9742e6 LZ |
245 | ret = trace_seq_puts(s, "rw-\n"); |
246 | WARN_ON_ONCE(!ret); | |
0722db01 | 247 | } |
be9742e6 LZ |
248 | |
249 | cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len); | |
250 | ||
0722db01 P |
251 | mutex_unlock(&ksym_tracer_mutex); |
252 | ||
be9742e6 LZ |
253 | kfree(s); |
254 | ||
255 | return cnt; | |
0722db01 P |
256 | } |
257 | ||
75e33751 XG |
258 | static void __ksym_trace_reset(void) |
259 | { | |
260 | struct trace_ksym *entry; | |
261 | struct hlist_node *node, *node1; | |
262 | ||
263 | mutex_lock(&ksym_tracer_mutex); | |
264 | hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head, | |
265 | ksym_hlist) { | |
24f1e32c | 266 | unregister_wide_hw_breakpoint(entry->ksym_hbp); |
75e33751 XG |
267 | ksym_filter_entry_count--; |
268 | hlist_del_rcu(&(entry->ksym_hlist)); | |
269 | synchronize_rcu(); | |
75e33751 XG |
270 | kfree(entry); |
271 | } | |
272 | mutex_unlock(&ksym_tracer_mutex); | |
273 | } | |
274 | ||
0722db01 P |
275 | static ssize_t ksym_trace_filter_write(struct file *file, |
276 | const char __user *buffer, | |
277 | size_t count, loff_t *ppos) | |
278 | { | |
279 | struct trace_ksym *entry; | |
280 | struct hlist_node *node; | |
281 | char *input_string, *ksymname = NULL; | |
282 | unsigned long ksym_addr = 0; | |
283 | int ret, op, changed = 0; | |
284 | ||
011ed568 | 285 | input_string = kzalloc(count + 1, GFP_KERNEL); |
0722db01 P |
286 | if (!input_string) |
287 | return -ENOMEM; | |
288 | ||
289 | if (copy_from_user(input_string, buffer, count)) { | |
290 | kfree(input_string); | |
291 | return -EFAULT; | |
292 | } | |
011ed568 | 293 | input_string[count] = '\0'; |
0722db01 | 294 | |
75e33751 XG |
295 | strstrip(input_string); |
296 | ||
297 | /* | |
298 | * Clear all breakpoints if: | |
299 | * 1: echo > ksym_trace_filter | |
300 | * 2: echo 0 > ksym_trace_filter | |
301 | * 3: echo "*:---" > ksym_trace_filter | |
302 | */ | |
303 | if (!input_string[0] || !strcmp(input_string, "0") || | |
304 | !strcmp(input_string, "*:---")) { | |
305 | __ksym_trace_reset(); | |
306 | kfree(input_string); | |
307 | return count; | |
308 | } | |
309 | ||
0722db01 P |
310 | ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr); |
311 | if (ret < 0) { | |
312 | kfree(input_string); | |
313 | return ret; | |
314 | } | |
315 | ||
316 | mutex_lock(&ksym_tracer_mutex); | |
317 | ||
318 | ret = -EINVAL; | |
319 | hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { | |
320 | if (entry->ksym_addr == ksym_addr) { | |
321 | /* Check for malformed request: (6) */ | |
24f1e32c | 322 | if (entry->type != op) |
0722db01 P |
323 | changed = 1; |
324 | else | |
558df6c8 | 325 | goto out; |
0722db01 P |
326 | break; |
327 | } | |
328 | } | |
329 | if (changed) { | |
24f1e32c FW |
330 | unregister_wide_hw_breakpoint(entry->ksym_hbp); |
331 | entry->type = op; | |
0722db01 | 332 | if (op > 0) { |
24f1e32c FW |
333 | entry->ksym_hbp = |
334 | register_wide_hw_breakpoint(entry->ksym_addr, | |
335 | entry->len, entry->type, | |
336 | ksym_hbp_handler, true); | |
337 | if (IS_ERR(entry->ksym_hbp)) | |
338 | entry->ksym_hbp = NULL; | |
339 | if (!entry->ksym_hbp) | |
558df6c8 LZ |
340 | goto out; |
341 | } | |
0722db01 P |
342 | ksym_filter_entry_count--; |
343 | hlist_del_rcu(&(entry->ksym_hlist)); | |
344 | synchronize_rcu(); | |
0722db01 | 345 | kfree(entry); |
8e068542 | 346 | ret = 0; |
558df6c8 | 347 | goto out; |
0722db01 P |
348 | } else { |
349 | /* Check for malformed request: (4) */ | |
350 | if (op == 0) | |
558df6c8 | 351 | goto out; |
0722db01 | 352 | ret = process_new_ksym_entry(ksymname, op, ksym_addr); |
0722db01 | 353 | } |
558df6c8 LZ |
354 | out: |
355 | mutex_unlock(&ksym_tracer_mutex); | |
0722db01 | 356 | |
0722db01 P |
357 | kfree(input_string); |
358 | ||
558df6c8 LZ |
359 | if (!ret) |
360 | ret = count; | |
0722db01 P |
361 | return ret; |
362 | } | |
363 | ||
364 | static const struct file_operations ksym_tracing_fops = { | |
365 | .open = tracing_open_generic, | |
366 | .read = ksym_trace_filter_read, | |
367 | .write = ksym_trace_filter_write, | |
368 | }; | |
369 | ||
370 | static void ksym_trace_reset(struct trace_array *tr) | |
371 | { | |
0722db01 | 372 | ksym_tracing_enabled = 0; |
75e33751 | 373 | __ksym_trace_reset(); |
0722db01 P |
374 | } |
375 | ||
376 | static int ksym_trace_init(struct trace_array *tr) | |
377 | { | |
378 | int cpu, ret = 0; | |
379 | ||
380 | for_each_online_cpu(cpu) | |
381 | tracing_reset(tr, cpu); | |
382 | ksym_tracing_enabled = 1; | |
383 | ksym_trace_array = tr; | |
384 | ||
385 | return ret; | |
386 | } | |
387 | ||
388 | static void ksym_trace_print_header(struct seq_file *m) | |
389 | { | |
0722db01 | 390 | seq_puts(m, |
d857ace1 XG |
391 | "# TASK-PID CPU# Symbol " |
392 | "Type Function\n"); | |
0722db01 | 393 | seq_puts(m, |
d857ace1 XG |
394 | "# | | | " |
395 | " | |\n"); | |
0722db01 P |
396 | } |
397 | ||
398 | static enum print_line_t ksym_trace_output(struct trace_iterator *iter) | |
399 | { | |
400 | struct trace_entry *entry = iter->ent; | |
401 | struct trace_seq *s = &iter->seq; | |
db59504d | 402 | struct ksym_trace_entry *field; |
0722db01 P |
403 | char str[KSYM_SYMBOL_LEN]; |
404 | int ret; | |
405 | ||
406 | if (entry->type != TRACE_KSYM) | |
407 | return TRACE_TYPE_UNHANDLED; | |
408 | ||
409 | trace_assign_type(field, entry); | |
410 | ||
24f1e32c FW |
411 | ret = trace_seq_printf(s, "%11s-%-5d [%03d] %pS", field->cmd, |
412 | entry->pid, iter->cpu, (char *)field->addr); | |
0722db01 P |
413 | if (!ret) |
414 | return TRACE_TYPE_PARTIAL_LINE; | |
415 | ||
db59504d | 416 | switch (field->type) { |
24f1e32c | 417 | case HW_BREAKPOINT_W: |
0722db01 P |
418 | ret = trace_seq_printf(s, " W "); |
419 | break; | |
24f1e32c | 420 | case HW_BREAKPOINT_R | HW_BREAKPOINT_W: |
0722db01 P |
421 | ret = trace_seq_printf(s, " RW "); |
422 | break; | |
423 | default: | |
424 | return TRACE_TYPE_PARTIAL_LINE; | |
425 | } | |
426 | ||
427 | if (!ret) | |
428 | return TRACE_TYPE_PARTIAL_LINE; | |
429 | ||
430 | sprint_symbol(str, field->ip); | |
d857ace1 | 431 | ret = trace_seq_printf(s, "%s\n", str); |
0722db01 P |
432 | if (!ret) |
433 | return TRACE_TYPE_PARTIAL_LINE; | |
434 | ||
435 | return TRACE_TYPE_HANDLED; | |
436 | } | |
437 | ||
438 | struct tracer ksym_tracer __read_mostly = | |
439 | { | |
440 | .name = "ksym_tracer", | |
441 | .init = ksym_trace_init, | |
442 | .reset = ksym_trace_reset, | |
443 | #ifdef CONFIG_FTRACE_SELFTEST | |
444 | .selftest = trace_selftest_startup_ksym, | |
445 | #endif | |
446 | .print_header = ksym_trace_print_header, | |
447 | .print_line = ksym_trace_output | |
448 | }; | |
449 | ||
450 | __init static int init_ksym_trace(void) | |
451 | { | |
452 | struct dentry *d_tracer; | |
453 | struct dentry *entry; | |
454 | ||
455 | d_tracer = tracing_init_dentry(); | |
456 | ksym_filter_entry_count = 0; | |
457 | ||
458 | entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer, | |
459 | NULL, &ksym_tracing_fops); | |
460 | if (!entry) | |
461 | pr_warning("Could not create debugfs " | |
462 | "'ksym_trace_filter' file\n"); | |
463 | ||
464 | return register_tracer(&ksym_tracer); | |
465 | } | |
466 | device_initcall(init_ksym_trace); | |
467 | ||
468 | ||
469 | #ifdef CONFIG_PROFILE_KSYM_TRACER | |
470 | static int ksym_tracer_stat_headers(struct seq_file *m) | |
471 | { | |
9d7e9344 LZ |
472 | seq_puts(m, " Access Type "); |
473 | seq_puts(m, " Symbol Counter\n"); | |
474 | seq_puts(m, " ----------- "); | |
475 | seq_puts(m, " ------ -------\n"); | |
0722db01 P |
476 | return 0; |
477 | } | |
478 | ||
479 | static int ksym_tracer_stat_show(struct seq_file *m, void *v) | |
480 | { | |
481 | struct hlist_node *stat = v; | |
482 | struct trace_ksym *entry; | |
483 | int access_type = 0; | |
484 | char fn_name[KSYM_NAME_LEN]; | |
485 | ||
486 | entry = hlist_entry(stat, struct trace_ksym, ksym_hlist); | |
487 | ||
24f1e32c | 488 | access_type = entry->type; |
0722db01 P |
489 | |
490 | switch (access_type) { | |
24f1e32c | 491 | case HW_BREAKPOINT_W: |
9d7e9344 | 492 | seq_puts(m, " W "); |
0722db01 | 493 | break; |
24f1e32c | 494 | case HW_BREAKPOINT_R | HW_BREAKPOINT_W: |
9d7e9344 | 495 | seq_puts(m, " RW "); |
0722db01 P |
496 | break; |
497 | default: | |
9d7e9344 | 498 | seq_puts(m, " NA "); |
0722db01 P |
499 | } |
500 | ||
501 | if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0) | |
9d7e9344 | 502 | seq_printf(m, " %-36s", fn_name); |
0722db01 | 503 | else |
9d7e9344 LZ |
504 | seq_printf(m, " %-36s", "<NA>"); |
505 | seq_printf(m, " %15lu\n", entry->counter); | |
0722db01 | 506 | |
0722db01 P |
507 | return 0; |
508 | } | |
509 | ||
510 | static void *ksym_tracer_stat_start(struct tracer_stat *trace) | |
511 | { | |
9d7e9344 | 512 | return ksym_filter_head.first; |
0722db01 P |
513 | } |
514 | ||
515 | static void * | |
516 | ksym_tracer_stat_next(void *v, int idx) | |
517 | { | |
518 | struct hlist_node *stat = v; | |
519 | ||
520 | return stat->next; | |
521 | } | |
522 | ||
523 | static struct tracer_stat ksym_tracer_stats = { | |
524 | .name = "ksym_tracer", | |
525 | .stat_start = ksym_tracer_stat_start, | |
526 | .stat_next = ksym_tracer_stat_next, | |
527 | .stat_headers = ksym_tracer_stat_headers, | |
528 | .stat_show = ksym_tracer_stat_show | |
529 | }; | |
530 | ||
531 | __init static int ksym_tracer_stat_init(void) | |
532 | { | |
533 | int ret; | |
534 | ||
535 | ret = register_stat_tracer(&ksym_tracer_stats); | |
536 | if (ret) { | |
537 | printk(KERN_WARNING "Warning: could not register " | |
538 | "ksym tracer stats\n"); | |
539 | return 1; | |
540 | } | |
541 | ||
542 | return 0; | |
543 | } | |
544 | fs_initcall(ksym_tracer_stat_init); | |
545 | #endif /* CONFIG_PROFILE_KSYM_TRACER */ |