1 /*
2 * Common code for probe-based Dynamic events.
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 version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16 *
17 * This code was copied from kernel/trace/trace_kprobe.c written by
18 * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
19 *
20 * Updates to make this generic:
21 * Copyright (C) IBM Corporation, 2010-2011
22 * Author: Srikar Dronamraju
23 */
24
25 #include "trace_probe.h"
26
27 const char *reserved_field_names[] = {
28 "common_type",
29 "common_flags",
30 "common_preempt_count",
31 "common_pid",
32 "common_tgid",
33 FIELD_STRING_IP,
34 FIELD_STRING_RETIP,
35 FIELD_STRING_FUNC,
36 };
37
38 /* Printing in basic type function template */
39 #define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt) \
40 int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, const char *name, \
41 void *data, void *ent) \
42 { \
43 trace_seq_printf(s, " %s=" fmt, name, *(type *)data); \
44 return !trace_seq_has_overflowed(s); \
45 } \
46 const char PRINT_TYPE_FMT_NAME(type)[] = fmt; \
47 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(type));
48
49 DEFINE_BASIC_PRINT_TYPE_FUNC(u8 , "0x%x")
50 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "0x%x")
51 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "0x%x")
52 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "0x%Lx")
53 DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d")
54 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
55 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
56 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
57
58 /* Print type function for string type */
PRINT_TYPE_FUNC_NAME(string)59 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
60 void *data, void *ent)
61 {
62 int len = *(u32 *)data >> 16;
63
64 if (!len)
65 trace_seq_printf(s, " %s=(fault)", name);
66 else
67 trace_seq_printf(s, " %s=\"%s\"", name,
68 (const char *)get_loc_data(data, ent));
69 return !trace_seq_has_overflowed(s);
70 }
71 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
72
73 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
74
75 #define CHECK_FETCH_FUNCS(method, fn) \
76 (((FETCH_FUNC_NAME(method, u8) == fn) || \
77 (FETCH_FUNC_NAME(method, u16) == fn) || \
78 (FETCH_FUNC_NAME(method, u32) == fn) || \
79 (FETCH_FUNC_NAME(method, u64) == fn) || \
80 (FETCH_FUNC_NAME(method, string) == fn) || \
81 (FETCH_FUNC_NAME(method, string_size) == fn)) \
82 && (fn != NULL))
83
84 /* Data fetch function templates */
85 #define DEFINE_FETCH_reg(type) \
86 void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \
87 { \
88 *(type *)dest = (type)regs_get_register(regs, \
89 (unsigned int)((unsigned long)offset)); \
90 } \
91 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
92 DEFINE_BASIC_FETCH_FUNCS(reg)
93 /* No string on the register */
94 #define fetch_reg_string NULL
95 #define fetch_reg_string_size NULL
96
97 #define DEFINE_FETCH_retval(type) \
98 void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \
99 void *dummy, void *dest) \
100 { \
101 *(type *)dest = (type)regs_return_value(regs); \
102 } \
103 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
104 DEFINE_BASIC_FETCH_FUNCS(retval)
105 /* No string on the retval */
106 #define fetch_retval_string NULL
107 #define fetch_retval_string_size NULL
108
109 /* Dereference memory access function */
110 struct deref_fetch_param {
111 struct fetch_param orig;
112 long offset;
113 fetch_func_t fetch;
114 fetch_func_t fetch_size;
115 };
116
117 #define DEFINE_FETCH_deref(type) \
118 void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
119 void *data, void *dest) \
120 { \
121 struct deref_fetch_param *dprm = data; \
122 unsigned long addr; \
123 call_fetch(&dprm->orig, regs, &addr); \
124 if (addr) { \
125 addr += dprm->offset; \
126 dprm->fetch(regs, (void *)addr, dest); \
127 } else \
128 *(type *)dest = 0; \
129 } \
130 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
131 DEFINE_BASIC_FETCH_FUNCS(deref)
DEFINE_FETCH_deref(string)132 DEFINE_FETCH_deref(string)
133
134 void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
135 void *data, void *dest)
136 {
137 struct deref_fetch_param *dprm = data;
138 unsigned long addr;
139
140 call_fetch(&dprm->orig, regs, &addr);
141 if (addr && dprm->fetch_size) {
142 addr += dprm->offset;
143 dprm->fetch_size(regs, (void *)addr, dest);
144 } else
145 *(string_size *)dest = 0;
146 }
147 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
148
update_deref_fetch_param(struct deref_fetch_param * data)149 static void update_deref_fetch_param(struct deref_fetch_param *data)
150 {
151 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
152 update_deref_fetch_param(data->orig.data);
153 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
154 update_symbol_cache(data->orig.data);
155 }
156 NOKPROBE_SYMBOL(update_deref_fetch_param);
157
free_deref_fetch_param(struct deref_fetch_param * data)158 static void free_deref_fetch_param(struct deref_fetch_param *data)
159 {
160 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
161 free_deref_fetch_param(data->orig.data);
162 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
163 free_symbol_cache(data->orig.data);
164 kfree(data);
165 }
166 NOKPROBE_SYMBOL(free_deref_fetch_param);
167
168 /* Bitfield fetch function */
169 struct bitfield_fetch_param {
170 struct fetch_param orig;
171 unsigned char hi_shift;
172 unsigned char low_shift;
173 };
174
175 #define DEFINE_FETCH_bitfield(type) \
176 void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \
177 void *data, void *dest) \
178 { \
179 struct bitfield_fetch_param *bprm = data; \
180 type buf = 0; \
181 call_fetch(&bprm->orig, regs, &buf); \
182 if (buf) { \
183 buf <<= bprm->hi_shift; \
184 buf >>= bprm->low_shift; \
185 } \
186 *(type *)dest = buf; \
187 } \
188 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
DEFINE_BASIC_FETCH_FUNCS(bitfield)189 DEFINE_BASIC_FETCH_FUNCS(bitfield)
190 #define fetch_bitfield_string NULL
191 #define fetch_bitfield_string_size NULL
192
193 static void
194 update_bitfield_fetch_param(struct bitfield_fetch_param *data)
195 {
196 /*
197 * Don't check the bitfield itself, because this must be the
198 * last fetch function.
199 */
200 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
201 update_deref_fetch_param(data->orig.data);
202 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
203 update_symbol_cache(data->orig.data);
204 }
205
206 static void
free_bitfield_fetch_param(struct bitfield_fetch_param * data)207 free_bitfield_fetch_param(struct bitfield_fetch_param *data)
208 {
209 /*
210 * Don't check the bitfield itself, because this must be the
211 * last fetch function.
212 */
213 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
214 free_deref_fetch_param(data->orig.data);
215 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
216 free_symbol_cache(data->orig.data);
217
218 kfree(data);
219 }
220
find_fetch_type(const char * type,const struct fetch_type * ftbl)221 static const struct fetch_type *find_fetch_type(const char *type,
222 const struct fetch_type *ftbl)
223 {
224 int i;
225
226 if (!type)
227 type = DEFAULT_FETCH_TYPE_STR;
228
229 /* Special case: bitfield */
230 if (*type == 'b') {
231 unsigned long bs;
232
233 type = strchr(type, '/');
234 if (!type)
235 goto fail;
236
237 type++;
238 if (kstrtoul(type, 0, &bs))
239 goto fail;
240
241 switch (bs) {
242 case 8:
243 return find_fetch_type("u8", ftbl);
244 case 16:
245 return find_fetch_type("u16", ftbl);
246 case 32:
247 return find_fetch_type("u32", ftbl);
248 case 64:
249 return find_fetch_type("u64", ftbl);
250 default:
251 goto fail;
252 }
253 }
254
255 for (i = 0; ftbl[i].name; i++) {
256 if (strcmp(type, ftbl[i].name) == 0)
257 return &ftbl[i];
258 }
259
260 fail:
261 return NULL;
262 }
263
264 /* Special function : only accept unsigned long */
fetch_kernel_stack_address(struct pt_regs * regs,void * dummy,void * dest)265 static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
266 {
267 *(unsigned long *)dest = kernel_stack_pointer(regs);
268 }
269 NOKPROBE_SYMBOL(fetch_kernel_stack_address);
270
fetch_user_stack_address(struct pt_regs * regs,void * dummy,void * dest)271 static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
272 {
273 *(unsigned long *)dest = user_stack_pointer(regs);
274 }
275 NOKPROBE_SYMBOL(fetch_user_stack_address);
276
get_fetch_size_function(const struct fetch_type * type,fetch_func_t orig_fn,const struct fetch_type * ftbl)277 static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
278 fetch_func_t orig_fn,
279 const struct fetch_type *ftbl)
280 {
281 int i;
282
283 if (type != &ftbl[FETCH_TYPE_STRING])
284 return NULL; /* Only string type needs size function */
285
286 for (i = 0; i < FETCH_MTD_END; i++)
287 if (type->fetch[i] == orig_fn)
288 return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
289
290 WARN_ON(1); /* This should not happen */
291
292 return NULL;
293 }
294
295 /* Split symbol and offset. */
traceprobe_split_symbol_offset(char * symbol,long * offset)296 int traceprobe_split_symbol_offset(char *symbol, long *offset)
297 {
298 char *tmp;
299 int ret;
300
301 if (!offset)
302 return -EINVAL;
303
304 tmp = strpbrk(symbol, "+-");
305 if (tmp) {
306 ret = kstrtol(tmp, 0, offset);
307 if (ret)
308 return ret;
309 *tmp = '\0';
310 } else
311 *offset = 0;
312
313 return 0;
314 }
315
316 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
317
parse_probe_vars(char * arg,const struct fetch_type * t,struct fetch_param * f,bool is_return,bool is_kprobe)318 static int parse_probe_vars(char *arg, const struct fetch_type *t,
319 struct fetch_param *f, bool is_return,
320 bool is_kprobe)
321 {
322 int ret = 0;
323 unsigned long param;
324
325 if (strcmp(arg, "retval") == 0) {
326 if (is_return)
327 f->fn = t->fetch[FETCH_MTD_retval];
328 else
329 ret = -EINVAL;
330 } else if (strncmp(arg, "stack", 5) == 0) {
331 if (arg[5] == '\0') {
332 if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
333 return -EINVAL;
334
335 if (is_kprobe)
336 f->fn = fetch_kernel_stack_address;
337 else
338 f->fn = fetch_user_stack_address;
339 } else if (isdigit(arg[5])) {
340 ret = kstrtoul(arg + 5, 10, ¶m);
341 if (ret || (is_kprobe && param > PARAM_MAX_STACK))
342 ret = -EINVAL;
343 else {
344 f->fn = t->fetch[FETCH_MTD_stack];
345 f->data = (void *)param;
346 }
347 } else
348 ret = -EINVAL;
349 } else
350 ret = -EINVAL;
351
352 return ret;
353 }
354
355 /* Recursive argument parser */
parse_probe_arg(char * arg,const struct fetch_type * t,struct fetch_param * f,bool is_return,bool is_kprobe,const struct fetch_type * ftbl)356 static int parse_probe_arg(char *arg, const struct fetch_type *t,
357 struct fetch_param *f, bool is_return, bool is_kprobe,
358 const struct fetch_type *ftbl)
359 {
360 unsigned long param;
361 long offset;
362 char *tmp;
363 int ret = 0;
364
365 switch (arg[0]) {
366 case '$':
367 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
368 break;
369
370 case '%': /* named register */
371 ret = regs_query_register_offset(arg + 1);
372 if (ret >= 0) {
373 f->fn = t->fetch[FETCH_MTD_reg];
374 f->data = (void *)(unsigned long)ret;
375 ret = 0;
376 }
377 break;
378
379 case '@': /* memory, file-offset or symbol */
380 if (isdigit(arg[1])) {
381 ret = kstrtoul(arg + 1, 0, ¶m);
382 if (ret)
383 break;
384
385 f->fn = t->fetch[FETCH_MTD_memory];
386 f->data = (void *)param;
387 } else if (arg[1] == '+') {
388 /* kprobes don't support file offsets */
389 if (is_kprobe)
390 return -EINVAL;
391
392 ret = kstrtol(arg + 2, 0, &offset);
393 if (ret)
394 break;
395
396 f->fn = t->fetch[FETCH_MTD_file_offset];
397 f->data = (void *)offset;
398 } else {
399 /* uprobes don't support symbols */
400 if (!is_kprobe)
401 return -EINVAL;
402
403 ret = traceprobe_split_symbol_offset(arg + 1, &offset);
404 if (ret)
405 break;
406
407 f->data = alloc_symbol_cache(arg + 1, offset);
408 if (f->data)
409 f->fn = t->fetch[FETCH_MTD_symbol];
410 }
411 break;
412
413 case '+': /* deref memory */
414 arg++; /* Skip '+', because kstrtol() rejects it. */
415 case '-':
416 tmp = strchr(arg, '(');
417 if (!tmp)
418 break;
419
420 *tmp = '\0';
421 ret = kstrtol(arg, 0, &offset);
422
423 if (ret)
424 break;
425
426 arg = tmp + 1;
427 tmp = strrchr(arg, ')');
428
429 if (tmp) {
430 struct deref_fetch_param *dprm;
431 const struct fetch_type *t2;
432
433 t2 = find_fetch_type(NULL, ftbl);
434 *tmp = '\0';
435 dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
436
437 if (!dprm)
438 return -ENOMEM;
439
440 dprm->offset = offset;
441 dprm->fetch = t->fetch[FETCH_MTD_memory];
442 dprm->fetch_size = get_fetch_size_function(t,
443 dprm->fetch, ftbl);
444 ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
445 is_kprobe, ftbl);
446 if (ret)
447 kfree(dprm);
448 else {
449 f->fn = t->fetch[FETCH_MTD_deref];
450 f->data = (void *)dprm;
451 }
452 }
453 break;
454 }
455 if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
456 pr_info("%s type has no corresponding fetch method.\n", t->name);
457 ret = -EINVAL;
458 }
459
460 return ret;
461 }
462
463 #define BYTES_TO_BITS(nb) ((BITS_PER_LONG * (nb)) / sizeof(long))
464
465 /* Bitfield type needs to be parsed into a fetch function */
__parse_bitfield_probe_arg(const char * bf,const struct fetch_type * t,struct fetch_param * f)466 static int __parse_bitfield_probe_arg(const char *bf,
467 const struct fetch_type *t,
468 struct fetch_param *f)
469 {
470 struct bitfield_fetch_param *bprm;
471 unsigned long bw, bo;
472 char *tail;
473
474 if (*bf != 'b')
475 return 0;
476
477 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
478 if (!bprm)
479 return -ENOMEM;
480
481 bprm->orig = *f;
482 f->fn = t->fetch[FETCH_MTD_bitfield];
483 f->data = (void *)bprm;
484 bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */
485
486 if (bw == 0 || *tail != '@')
487 return -EINVAL;
488
489 bf = tail + 1;
490 bo = simple_strtoul(bf, &tail, 0);
491
492 if (tail == bf || *tail != '/')
493 return -EINVAL;
494
495 bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
496 bprm->low_shift = bprm->hi_shift + bo;
497
498 return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
499 }
500
501 /* String length checking wrapper */
traceprobe_parse_probe_arg(char * arg,ssize_t * size,struct probe_arg * parg,bool is_return,bool is_kprobe,const struct fetch_type * ftbl)502 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
503 struct probe_arg *parg, bool is_return, bool is_kprobe,
504 const struct fetch_type *ftbl)
505 {
506 const char *t;
507 int ret;
508
509 if (strlen(arg) > MAX_ARGSTR_LEN) {
510 pr_info("Argument is too long.: %s\n", arg);
511 return -ENOSPC;
512 }
513 parg->comm = kstrdup(arg, GFP_KERNEL);
514 if (!parg->comm) {
515 pr_info("Failed to allocate memory for command '%s'.\n", arg);
516 return -ENOMEM;
517 }
518 t = strchr(parg->comm, ':');
519 if (t) {
520 arg[t - parg->comm] = '\0';
521 t++;
522 }
523 parg->type = find_fetch_type(t, ftbl);
524 if (!parg->type) {
525 pr_info("Unsupported type: %s\n", t);
526 return -EINVAL;
527 }
528 parg->offset = *size;
529 *size += parg->type->size;
530 ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
531 is_kprobe, ftbl);
532
533 if (ret >= 0 && t != NULL)
534 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
535
536 if (ret >= 0) {
537 parg->fetch_size.fn = get_fetch_size_function(parg->type,
538 parg->fetch.fn,
539 ftbl);
540 parg->fetch_size.data = parg->fetch.data;
541 }
542
543 return ret;
544 }
545
546 /* Return 1 if name is reserved or already used by another argument */
traceprobe_conflict_field_name(const char * name,struct probe_arg * args,int narg)547 int traceprobe_conflict_field_name(const char *name,
548 struct probe_arg *args, int narg)
549 {
550 int i;
551
552 for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
553 if (strcmp(reserved_field_names[i], name) == 0)
554 return 1;
555
556 for (i = 0; i < narg; i++)
557 if (strcmp(args[i].name, name) == 0)
558 return 1;
559
560 return 0;
561 }
562
traceprobe_update_arg(struct probe_arg * arg)563 void traceprobe_update_arg(struct probe_arg *arg)
564 {
565 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
566 update_bitfield_fetch_param(arg->fetch.data);
567 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
568 update_deref_fetch_param(arg->fetch.data);
569 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
570 update_symbol_cache(arg->fetch.data);
571 }
572
traceprobe_free_probe_arg(struct probe_arg * arg)573 void traceprobe_free_probe_arg(struct probe_arg *arg)
574 {
575 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
576 free_bitfield_fetch_param(arg->fetch.data);
577 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
578 free_deref_fetch_param(arg->fetch.data);
579 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
580 free_symbol_cache(arg->fetch.data);
581
582 kfree(arg->name);
583 kfree(arg->comm);
584 }
585
traceprobe_command(const char * buf,int (* createfn)(int,char **))586 int traceprobe_command(const char *buf, int (*createfn)(int, char **))
587 {
588 char **argv;
589 int argc, ret;
590
591 argc = 0;
592 ret = 0;
593 argv = argv_split(GFP_KERNEL, buf, &argc);
594 if (!argv)
595 return -ENOMEM;
596
597 if (argc)
598 ret = createfn(argc, argv);
599
600 argv_free(argv);
601
602 return ret;
603 }
604
605 #define WRITE_BUFSIZE 4096
606
traceprobe_probes_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos,int (* createfn)(int,char **))607 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
608 size_t count, loff_t *ppos,
609 int (*createfn)(int, char **))
610 {
611 char *kbuf, *tmp;
612 int ret = 0;
613 size_t done = 0;
614 size_t size;
615
616 kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
617 if (!kbuf)
618 return -ENOMEM;
619
620 while (done < count) {
621 size = count - done;
622
623 if (size >= WRITE_BUFSIZE)
624 size = WRITE_BUFSIZE - 1;
625
626 if (copy_from_user(kbuf, buffer + done, size)) {
627 ret = -EFAULT;
628 goto out;
629 }
630 kbuf[size] = '\0';
631 tmp = strchr(kbuf, '\n');
632
633 if (tmp) {
634 *tmp = '\0';
635 size = tmp - kbuf + 1;
636 } else if (done + size < count) {
637 pr_warning("Line length is too long: "
638 "Should be less than %d.", WRITE_BUFSIZE);
639 ret = -EINVAL;
640 goto out;
641 }
642 done += size;
643 /* Remove comments */
644 tmp = strchr(kbuf, '#');
645
646 if (tmp)
647 *tmp = '\0';
648
649 ret = traceprobe_command(kbuf, createfn);
650 if (ret)
651 goto out;
652 }
653 ret = done;
654
655 out:
656 kfree(kbuf);
657
658 return ret;
659 }
660
__set_print_fmt(struct trace_probe * tp,char * buf,int len,bool is_return)661 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
662 bool is_return)
663 {
664 int i;
665 int pos = 0;
666
667 const char *fmt, *arg;
668
669 if (!is_return) {
670 fmt = "(%lx)";
671 arg = "REC->" FIELD_STRING_IP;
672 } else {
673 fmt = "(%lx <- %lx)";
674 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
675 }
676
677 /* When len=0, we just calculate the needed length */
678 #define LEN_OR_ZERO (len ? len - pos : 0)
679
680 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
681
682 for (i = 0; i < tp->nr_args; i++) {
683 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
684 tp->args[i].name, tp->args[i].type->fmt);
685 }
686
687 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
688
689 for (i = 0; i < tp->nr_args; i++) {
690 if (strcmp(tp->args[i].type->name, "string") == 0)
691 pos += snprintf(buf + pos, LEN_OR_ZERO,
692 ", __get_str(%s)",
693 tp->args[i].name);
694 else
695 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
696 tp->args[i].name);
697 }
698
699 #undef LEN_OR_ZERO
700
701 /* return the length of print_fmt */
702 return pos;
703 }
704
set_print_fmt(struct trace_probe * tp,bool is_return)705 int set_print_fmt(struct trace_probe *tp, bool is_return)
706 {
707 int len;
708 char *print_fmt;
709
710 /* First: called with 0 length to calculate the needed length */
711 len = __set_print_fmt(tp, NULL, 0, is_return);
712 print_fmt = kmalloc(len + 1, GFP_KERNEL);
713 if (!print_fmt)
714 return -ENOMEM;
715
716 /* Second: actually write the @print_fmt */
717 __set_print_fmt(tp, print_fmt, len + 1, is_return);
718 tp->call.print_fmt = print_fmt;
719
720 return 0;
721 }
722