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 return trace_seq_printf(s, " %s=" fmt, name, *(type *)data); \
44 } \
45 const char PRINT_TYPE_FMT_NAME(type)[] = fmt; \
46 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(type));
47
48 DEFINE_BASIC_PRINT_TYPE_FUNC(u8 , "0x%x")
49 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "0x%x")
50 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "0x%x")
51 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "0x%Lx")
52 DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d")
53 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
54 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
55 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
56
57 /* Print type function for string type */
PRINT_TYPE_FUNC_NAME(string)58 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
59 void *data, void *ent)
60 {
61 int len = *(u32 *)data >> 16;
62
63 if (!len)
64 return trace_seq_printf(s, " %s=(fault)", name);
65 else
66 return trace_seq_printf(s, " %s=\"%s\"", name,
67 (const char *)get_loc_data(data, ent));
68 }
69 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
70
71 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
72
73 #define CHECK_FETCH_FUNCS(method, fn) \
74 (((FETCH_FUNC_NAME(method, u8) == fn) || \
75 (FETCH_FUNC_NAME(method, u16) == fn) || \
76 (FETCH_FUNC_NAME(method, u32) == fn) || \
77 (FETCH_FUNC_NAME(method, u64) == fn) || \
78 (FETCH_FUNC_NAME(method, string) == fn) || \
79 (FETCH_FUNC_NAME(method, string_size) == fn)) \
80 && (fn != NULL))
81
82 /* Data fetch function templates */
83 #define DEFINE_FETCH_reg(type) \
84 void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \
85 { \
86 *(type *)dest = (type)regs_get_register(regs, \
87 (unsigned int)((unsigned long)offset)); \
88 } \
89 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
90 DEFINE_BASIC_FETCH_FUNCS(reg)
91 /* No string on the register */
92 #define fetch_reg_string NULL
93 #define fetch_reg_string_size NULL
94
95 #define DEFINE_FETCH_retval(type) \
96 void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \
97 void *dummy, void *dest) \
98 { \
99 *(type *)dest = (type)regs_return_value(regs); \
100 } \
101 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
102 DEFINE_BASIC_FETCH_FUNCS(retval)
103 /* No string on the retval */
104 #define fetch_retval_string NULL
105 #define fetch_retval_string_size NULL
106
107 /* Dereference memory access function */
108 struct deref_fetch_param {
109 struct fetch_param orig;
110 long offset;
111 fetch_func_t fetch;
112 fetch_func_t fetch_size;
113 };
114
115 #define DEFINE_FETCH_deref(type) \
116 void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
117 void *data, void *dest) \
118 { \
119 struct deref_fetch_param *dprm = data; \
120 unsigned long addr; \
121 call_fetch(&dprm->orig, regs, &addr); \
122 if (addr) { \
123 addr += dprm->offset; \
124 dprm->fetch(regs, (void *)addr, dest); \
125 } else \
126 *(type *)dest = 0; \
127 } \
128 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
129 DEFINE_BASIC_FETCH_FUNCS(deref)
DEFINE_FETCH_deref(string)130 DEFINE_FETCH_deref(string)
131
132 void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
133 void *data, void *dest)
134 {
135 struct deref_fetch_param *dprm = data;
136 unsigned long addr;
137
138 call_fetch(&dprm->orig, regs, &addr);
139 if (addr && dprm->fetch_size) {
140 addr += dprm->offset;
141 dprm->fetch_size(regs, (void *)addr, dest);
142 } else
143 *(string_size *)dest = 0;
144 }
145 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
146
update_deref_fetch_param(struct deref_fetch_param * data)147 static void update_deref_fetch_param(struct deref_fetch_param *data)
148 {
149 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
150 update_deref_fetch_param(data->orig.data);
151 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
152 update_symbol_cache(data->orig.data);
153 }
154 NOKPROBE_SYMBOL(update_deref_fetch_param);
155
free_deref_fetch_param(struct deref_fetch_param * data)156 static void free_deref_fetch_param(struct deref_fetch_param *data)
157 {
158 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
159 free_deref_fetch_param(data->orig.data);
160 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
161 free_symbol_cache(data->orig.data);
162 kfree(data);
163 }
164 NOKPROBE_SYMBOL(free_deref_fetch_param);
165
166 /* Bitfield fetch function */
167 struct bitfield_fetch_param {
168 struct fetch_param orig;
169 unsigned char hi_shift;
170 unsigned char low_shift;
171 };
172
173 #define DEFINE_FETCH_bitfield(type) \
174 void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \
175 void *data, void *dest) \
176 { \
177 struct bitfield_fetch_param *bprm = data; \
178 type buf = 0; \
179 call_fetch(&bprm->orig, regs, &buf); \
180 if (buf) { \
181 buf <<= bprm->hi_shift; \
182 buf >>= bprm->low_shift; \
183 } \
184 *(type *)dest = buf; \
185 } \
186 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
DEFINE_BASIC_FETCH_FUNCS(bitfield)187 DEFINE_BASIC_FETCH_FUNCS(bitfield)
188 #define fetch_bitfield_string NULL
189 #define fetch_bitfield_string_size NULL
190
191 static void
192 update_bitfield_fetch_param(struct bitfield_fetch_param *data)
193 {
194 /*
195 * Don't check the bitfield itself, because this must be the
196 * last fetch function.
197 */
198 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
199 update_deref_fetch_param(data->orig.data);
200 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
201 update_symbol_cache(data->orig.data);
202 }
203
204 static void
free_bitfield_fetch_param(struct bitfield_fetch_param * data)205 free_bitfield_fetch_param(struct bitfield_fetch_param *data)
206 {
207 /*
208 * Don't check the bitfield itself, because this must be the
209 * last fetch function.
210 */
211 if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
212 free_deref_fetch_param(data->orig.data);
213 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
214 free_symbol_cache(data->orig.data);
215
216 kfree(data);
217 }
218
find_fetch_type(const char * type,const struct fetch_type * ftbl)219 static const struct fetch_type *find_fetch_type(const char *type,
220 const struct fetch_type *ftbl)
221 {
222 int i;
223
224 if (!type)
225 type = DEFAULT_FETCH_TYPE_STR;
226
227 /* Special case: bitfield */
228 if (*type == 'b') {
229 unsigned long bs;
230
231 type = strchr(type, '/');
232 if (!type)
233 goto fail;
234
235 type++;
236 if (kstrtoul(type, 0, &bs))
237 goto fail;
238
239 switch (bs) {
240 case 8:
241 return find_fetch_type("u8", ftbl);
242 case 16:
243 return find_fetch_type("u16", ftbl);
244 case 32:
245 return find_fetch_type("u32", ftbl);
246 case 64:
247 return find_fetch_type("u64", ftbl);
248 default:
249 goto fail;
250 }
251 }
252
253 for (i = 0; ftbl[i].name; i++) {
254 if (strcmp(type, ftbl[i].name) == 0)
255 return &ftbl[i];
256 }
257
258 fail:
259 return NULL;
260 }
261
262 /* Special function : only accept unsigned long */
fetch_kernel_stack_address(struct pt_regs * regs,void * dummy,void * dest)263 static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
264 {
265 *(unsigned long *)dest = kernel_stack_pointer(regs);
266 }
267 NOKPROBE_SYMBOL(fetch_kernel_stack_address);
268
fetch_user_stack_address(struct pt_regs * regs,void * dummy,void * dest)269 static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
270 {
271 *(unsigned long *)dest = user_stack_pointer(regs);
272 }
273 NOKPROBE_SYMBOL(fetch_user_stack_address);
274
get_fetch_size_function(const struct fetch_type * type,fetch_func_t orig_fn,const struct fetch_type * ftbl)275 static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
276 fetch_func_t orig_fn,
277 const struct fetch_type *ftbl)
278 {
279 int i;
280
281 if (type != &ftbl[FETCH_TYPE_STRING])
282 return NULL; /* Only string type needs size function */
283
284 for (i = 0; i < FETCH_MTD_END; i++)
285 if (type->fetch[i] == orig_fn)
286 return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
287
288 WARN_ON(1); /* This should not happen */
289
290 return NULL;
291 }
292
293 /* Split symbol and offset. */
traceprobe_split_symbol_offset(char * symbol,unsigned long * offset)294 int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
295 {
296 char *tmp;
297 int ret;
298
299 if (!offset)
300 return -EINVAL;
301
302 tmp = strchr(symbol, '+');
303 if (tmp) {
304 /* skip sign because kstrtoul doesn't accept '+' */
305 ret = kstrtoul(tmp + 1, 0, offset);
306 if (ret)
307 return ret;
308
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)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 {
359 const struct fetch_type *ftbl;
360 unsigned long param;
361 long offset;
362 char *tmp;
363 int ret = 0;
364
365 ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
366 BUG_ON(ftbl == NULL);
367
368 switch (arg[0]) {
369 case '$':
370 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
371 break;
372
373 case '%': /* named register */
374 ret = regs_query_register_offset(arg + 1);
375 if (ret >= 0) {
376 f->fn = t->fetch[FETCH_MTD_reg];
377 f->data = (void *)(unsigned long)ret;
378 ret = 0;
379 }
380 break;
381
382 case '@': /* memory, file-offset or symbol */
383 if (isdigit(arg[1])) {
384 ret = kstrtoul(arg + 1, 0, ¶m);
385 if (ret)
386 break;
387
388 f->fn = t->fetch[FETCH_MTD_memory];
389 f->data = (void *)param;
390 } else if (arg[1] == '+') {
391 /* kprobes don't support file offsets */
392 if (is_kprobe)
393 return -EINVAL;
394
395 ret = kstrtol(arg + 2, 0, &offset);
396 if (ret)
397 break;
398
399 f->fn = t->fetch[FETCH_MTD_file_offset];
400 f->data = (void *)offset;
401 } else {
402 /* uprobes don't support symbols */
403 if (!is_kprobe)
404 return -EINVAL;
405
406 ret = traceprobe_split_symbol_offset(arg + 1, &offset);
407 if (ret)
408 break;
409
410 f->data = alloc_symbol_cache(arg + 1, offset);
411 if (f->data)
412 f->fn = t->fetch[FETCH_MTD_symbol];
413 }
414 break;
415
416 case '+': /* deref memory */
417 arg++; /* Skip '+', because kstrtol() rejects it. */
418 case '-':
419 tmp = strchr(arg, '(');
420 if (!tmp)
421 break;
422
423 *tmp = '\0';
424 ret = kstrtol(arg, 0, &offset);
425
426 if (ret)
427 break;
428
429 arg = tmp + 1;
430 tmp = strrchr(arg, ')');
431
432 if (tmp) {
433 struct deref_fetch_param *dprm;
434 const struct fetch_type *t2;
435
436 t2 = find_fetch_type(NULL, ftbl);
437 *tmp = '\0';
438 dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
439
440 if (!dprm)
441 return -ENOMEM;
442
443 dprm->offset = offset;
444 dprm->fetch = t->fetch[FETCH_MTD_memory];
445 dprm->fetch_size = get_fetch_size_function(t,
446 dprm->fetch, ftbl);
447 ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
448 is_kprobe);
449 if (ret)
450 kfree(dprm);
451 else {
452 f->fn = t->fetch[FETCH_MTD_deref];
453 f->data = (void *)dprm;
454 }
455 }
456 break;
457 }
458 if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
459 pr_info("%s type has no corresponding fetch method.\n", t->name);
460 ret = -EINVAL;
461 }
462
463 return ret;
464 }
465
466 #define BYTES_TO_BITS(nb) ((BITS_PER_LONG * (nb)) / sizeof(long))
467
468 /* 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)469 static int __parse_bitfield_probe_arg(const char *bf,
470 const struct fetch_type *t,
471 struct fetch_param *f)
472 {
473 struct bitfield_fetch_param *bprm;
474 unsigned long bw, bo;
475 char *tail;
476
477 if (*bf != 'b')
478 return 0;
479
480 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
481 if (!bprm)
482 return -ENOMEM;
483
484 bprm->orig = *f;
485 f->fn = t->fetch[FETCH_MTD_bitfield];
486 f->data = (void *)bprm;
487 bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */
488
489 if (bw == 0 || *tail != '@')
490 return -EINVAL;
491
492 bf = tail + 1;
493 bo = simple_strtoul(bf, &tail, 0);
494
495 if (tail == bf || *tail != '/')
496 return -EINVAL;
497
498 bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
499 bprm->low_shift = bprm->hi_shift + bo;
500
501 return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
502 }
503
504 /* String length checking wrapper */
traceprobe_parse_probe_arg(char * arg,ssize_t * size,struct probe_arg * parg,bool is_return,bool is_kprobe)505 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
506 struct probe_arg *parg, bool is_return, bool is_kprobe)
507 {
508 const struct fetch_type *ftbl;
509 const char *t;
510 int ret;
511
512 ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
513 BUG_ON(ftbl == NULL);
514
515 if (strlen(arg) > MAX_ARGSTR_LEN) {
516 pr_info("Argument is too long.: %s\n", arg);
517 return -ENOSPC;
518 }
519 parg->comm = kstrdup(arg, GFP_KERNEL);
520 if (!parg->comm) {
521 pr_info("Failed to allocate memory for command '%s'.\n", arg);
522 return -ENOMEM;
523 }
524 t = strchr(parg->comm, ':');
525 if (t) {
526 arg[t - parg->comm] = '\0';
527 t++;
528 }
529 parg->type = find_fetch_type(t, ftbl);
530 if (!parg->type) {
531 pr_info("Unsupported type: %s\n", t);
532 return -EINVAL;
533 }
534 parg->offset = *size;
535 *size += parg->type->size;
536 ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);
537
538 if (ret >= 0 && t != NULL)
539 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
540
541 if (ret >= 0) {
542 parg->fetch_size.fn = get_fetch_size_function(parg->type,
543 parg->fetch.fn,
544 ftbl);
545 parg->fetch_size.data = parg->fetch.data;
546 }
547
548 return ret;
549 }
550
551 /* 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)552 int traceprobe_conflict_field_name(const char *name,
553 struct probe_arg *args, int narg)
554 {
555 int i;
556
557 for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
558 if (strcmp(reserved_field_names[i], name) == 0)
559 return 1;
560
561 for (i = 0; i < narg; i++)
562 if (strcmp(args[i].name, name) == 0)
563 return 1;
564
565 return 0;
566 }
567
traceprobe_update_arg(struct probe_arg * arg)568 void traceprobe_update_arg(struct probe_arg *arg)
569 {
570 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
571 update_bitfield_fetch_param(arg->fetch.data);
572 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
573 update_deref_fetch_param(arg->fetch.data);
574 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
575 update_symbol_cache(arg->fetch.data);
576 }
577
traceprobe_free_probe_arg(struct probe_arg * arg)578 void traceprobe_free_probe_arg(struct probe_arg *arg)
579 {
580 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
581 free_bitfield_fetch_param(arg->fetch.data);
582 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
583 free_deref_fetch_param(arg->fetch.data);
584 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
585 free_symbol_cache(arg->fetch.data);
586
587 kfree(arg->name);
588 kfree(arg->comm);
589 }
590
traceprobe_command(const char * buf,int (* createfn)(int,char **))591 int traceprobe_command(const char *buf, int (*createfn)(int, char **))
592 {
593 char **argv;
594 int argc, ret;
595
596 argc = 0;
597 ret = 0;
598 argv = argv_split(GFP_KERNEL, buf, &argc);
599 if (!argv)
600 return -ENOMEM;
601
602 if (argc)
603 ret = createfn(argc, argv);
604
605 argv_free(argv);
606
607 return ret;
608 }
609
610 #define WRITE_BUFSIZE 4096
611
traceprobe_probes_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos,int (* createfn)(int,char **))612 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
613 size_t count, loff_t *ppos,
614 int (*createfn)(int, char **))
615 {
616 char *kbuf, *tmp;
617 int ret = 0;
618 size_t done = 0;
619 size_t size;
620
621 kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
622 if (!kbuf)
623 return -ENOMEM;
624
625 while (done < count) {
626 size = count - done;
627
628 if (size >= WRITE_BUFSIZE)
629 size = WRITE_BUFSIZE - 1;
630
631 if (copy_from_user(kbuf, buffer + done, size)) {
632 ret = -EFAULT;
633 goto out;
634 }
635 kbuf[size] = '\0';
636 tmp = strchr(kbuf, '\n');
637
638 if (tmp) {
639 *tmp = '\0';
640 size = tmp - kbuf + 1;
641 } else if (done + size < count) {
642 pr_warning("Line length is too long: "
643 "Should be less than %d.", WRITE_BUFSIZE);
644 ret = -EINVAL;
645 goto out;
646 }
647 done += size;
648 /* Remove comments */
649 tmp = strchr(kbuf, '#');
650
651 if (tmp)
652 *tmp = '\0';
653
654 ret = traceprobe_command(kbuf, createfn);
655 if (ret)
656 goto out;
657 }
658 ret = done;
659
660 out:
661 kfree(kbuf);
662
663 return ret;
664 }
665
__set_print_fmt(struct trace_probe * tp,char * buf,int len,bool is_return)666 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
667 bool is_return)
668 {
669 int i;
670 int pos = 0;
671
672 const char *fmt, *arg;
673
674 if (!is_return) {
675 fmt = "(%lx)";
676 arg = "REC->" FIELD_STRING_IP;
677 } else {
678 fmt = "(%lx <- %lx)";
679 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
680 }
681
682 /* When len=0, we just calculate the needed length */
683 #define LEN_OR_ZERO (len ? len - pos : 0)
684
685 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
686
687 for (i = 0; i < tp->nr_args; i++) {
688 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
689 tp->args[i].name, tp->args[i].type->fmt);
690 }
691
692 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
693
694 for (i = 0; i < tp->nr_args; i++) {
695 if (strcmp(tp->args[i].type->name, "string") == 0)
696 pos += snprintf(buf + pos, LEN_OR_ZERO,
697 ", __get_str(%s)",
698 tp->args[i].name);
699 else
700 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
701 tp->args[i].name);
702 }
703
704 #undef LEN_OR_ZERO
705
706 /* return the length of print_fmt */
707 return pos;
708 }
709
set_print_fmt(struct trace_probe * tp,bool is_return)710 int set_print_fmt(struct trace_probe *tp, bool is_return)
711 {
712 int len;
713 char *print_fmt;
714
715 /* First: called with 0 length to calculate the needed length */
716 len = __set_print_fmt(tp, NULL, 0, is_return);
717 print_fmt = kmalloc(len + 1, GFP_KERNEL);
718 if (!print_fmt)
719 return -ENOMEM;
720
721 /* Second: actually write the @print_fmt */
722 __set_print_fmt(tp, print_fmt, len + 1, is_return);
723 tp->call.print_fmt = print_fmt;
724
725 return 0;
726 }
727