Merge tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...
[muen/linux.git] / kernel / trace / trace_probe.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Common code for probe-based Dynamic events.
4  *
5  * This code was copied from kernel/trace/trace_kprobe.c written by
6  * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
7  *
8  * Updates to make this generic:
9  * Copyright (C) IBM Corporation, 2010-2011
10  * Author:     Srikar Dronamraju
11  */
12 #define pr_fmt(fmt)     "trace_probe: " fmt
13
14 #include "trace_probe.h"
15
16 const char *reserved_field_names[] = {
17         "common_type",
18         "common_flags",
19         "common_preempt_count",
20         "common_pid",
21         "common_tgid",
22         FIELD_STRING_IP,
23         FIELD_STRING_RETIP,
24         FIELD_STRING_FUNC,
25 };
26
27 /* Printing  in basic type function template */
28 #define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)                  \
29 int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
30 {                                                                       \
31         trace_seq_printf(s, fmt, *(type *)data);                        \
32         return !trace_seq_has_overflowed(s);                            \
33 }                                                                       \
34 const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;
35
36 DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
37 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
38 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
39 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
40 DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
41 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
42 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
43 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
44 DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
45 DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
46 DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
47 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
48
49 int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
50 {
51         trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
52         return !trace_seq_has_overflowed(s);
53 }
54 const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";
55
56 /* Print type function for string type */
57 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
58 {
59         int len = *(u32 *)data >> 16;
60
61         if (!len)
62                 trace_seq_puts(s, "(fault)");
63         else
64                 trace_seq_printf(s, "\"%s\"",
65                                  (const char *)get_loc_data(data, ent));
66         return !trace_seq_has_overflowed(s);
67 }
68
69 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
70
71 /* Fetch type information table */
72 static const struct fetch_type probe_fetch_types[] = {
73         /* Special types */
74         __ASSIGN_FETCH_TYPE("string", string, string, sizeof(u32), 1,
75                             "__data_loc char[]"),
76         /* Basic types */
77         ASSIGN_FETCH_TYPE(u8,  u8,  0),
78         ASSIGN_FETCH_TYPE(u16, u16, 0),
79         ASSIGN_FETCH_TYPE(u32, u32, 0),
80         ASSIGN_FETCH_TYPE(u64, u64, 0),
81         ASSIGN_FETCH_TYPE(s8,  u8,  1),
82         ASSIGN_FETCH_TYPE(s16, u16, 1),
83         ASSIGN_FETCH_TYPE(s32, u32, 1),
84         ASSIGN_FETCH_TYPE(s64, u64, 1),
85         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
86         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
87         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
88         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
89         ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),
90
91         ASSIGN_FETCH_TYPE_END
92 };
93
94 static const struct fetch_type *find_fetch_type(const char *type)
95 {
96         int i;
97
98         if (!type)
99                 type = DEFAULT_FETCH_TYPE_STR;
100
101         /* Special case: bitfield */
102         if (*type == 'b') {
103                 unsigned long bs;
104
105                 type = strchr(type, '/');
106                 if (!type)
107                         goto fail;
108
109                 type++;
110                 if (kstrtoul(type, 0, &bs))
111                         goto fail;
112
113                 switch (bs) {
114                 case 8:
115                         return find_fetch_type("u8");
116                 case 16:
117                         return find_fetch_type("u16");
118                 case 32:
119                         return find_fetch_type("u32");
120                 case 64:
121                         return find_fetch_type("u64");
122                 default:
123                         goto fail;
124                 }
125         }
126
127         for (i = 0; probe_fetch_types[i].name; i++) {
128                 if (strcmp(type, probe_fetch_types[i].name) == 0)
129                         return &probe_fetch_types[i];
130         }
131
132 fail:
133         return NULL;
134 }
135
136 /* Split symbol and offset. */
137 int traceprobe_split_symbol_offset(char *symbol, long *offset)
138 {
139         char *tmp;
140         int ret;
141
142         if (!offset)
143                 return -EINVAL;
144
145         tmp = strpbrk(symbol, "+-");
146         if (tmp) {
147                 ret = kstrtol(tmp, 0, offset);
148                 if (ret)
149                         return ret;
150                 *tmp = '\0';
151         } else
152                 *offset = 0;
153
154         return 0;
155 }
156
157 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
158
159 static int parse_probe_vars(char *arg, const struct fetch_type *t,
160                             struct fetch_insn *code, unsigned int flags)
161 {
162         int ret = 0;
163         unsigned long param;
164
165         if (strcmp(arg, "retval") == 0) {
166                 if (flags & TPARG_FL_RETURN)
167                         code->op = FETCH_OP_RETVAL;
168                 else
169                         ret = -EINVAL;
170         } else if (strncmp(arg, "stack", 5) == 0) {
171                 if (arg[5] == '\0') {
172                         code->op = FETCH_OP_STACKP;
173                 } else if (isdigit(arg[5])) {
174                         ret = kstrtoul(arg + 5, 10, &param);
175                         if (ret || ((flags & TPARG_FL_KERNEL) &&
176                                     param > PARAM_MAX_STACK))
177                                 ret = -EINVAL;
178                         else {
179                                 code->op = FETCH_OP_STACK;
180                                 code->param = (unsigned int)param;
181                         }
182                 } else
183                         ret = -EINVAL;
184         } else if (strcmp(arg, "comm") == 0) {
185                 code->op = FETCH_OP_COMM;
186 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
187         } else if (((flags & TPARG_FL_MASK) ==
188                     (TPARG_FL_KERNEL | TPARG_FL_FENTRY)) &&
189                    strncmp(arg, "arg", 3) == 0) {
190                 if (!isdigit(arg[3]))
191                         return -EINVAL;
192                 ret = kstrtoul(arg + 3, 10, &param);
193                 if (ret || !param || param > PARAM_MAX_STACK)
194                         return -EINVAL;
195                 code->op = FETCH_OP_ARG;
196                 code->param = (unsigned int)param - 1;
197 #endif
198         } else
199                 ret = -EINVAL;
200
201         return ret;
202 }
203
204 /* Recursive argument parser */
205 static int
206 parse_probe_arg(char *arg, const struct fetch_type *type,
207                 struct fetch_insn **pcode, struct fetch_insn *end,
208                 unsigned int flags)
209 {
210         struct fetch_insn *code = *pcode;
211         unsigned long param;
212         long offset = 0;
213         char *tmp;
214         int ret = 0;
215
216         switch (arg[0]) {
217         case '$':
218                 ret = parse_probe_vars(arg + 1, type, code, flags);
219                 break;
220
221         case '%':       /* named register */
222                 ret = regs_query_register_offset(arg + 1);
223                 if (ret >= 0) {
224                         code->op = FETCH_OP_REG;
225                         code->param = (unsigned int)ret;
226                         ret = 0;
227                 }
228                 break;
229
230         case '@':       /* memory, file-offset or symbol */
231                 if (isdigit(arg[1])) {
232                         ret = kstrtoul(arg + 1, 0, &param);
233                         if (ret)
234                                 break;
235                         /* load address */
236                         code->op = FETCH_OP_IMM;
237                         code->immediate = param;
238                 } else if (arg[1] == '+') {
239                         /* kprobes don't support file offsets */
240                         if (flags & TPARG_FL_KERNEL)
241                                 return -EINVAL;
242
243                         ret = kstrtol(arg + 2, 0, &offset);
244                         if (ret)
245                                 break;
246
247                         code->op = FETCH_OP_FOFFS;
248                         code->immediate = (unsigned long)offset;  // imm64?
249                 } else {
250                         /* uprobes don't support symbols */
251                         if (!(flags & TPARG_FL_KERNEL))
252                                 return -EINVAL;
253
254                         /* Preserve symbol for updating */
255                         code->op = FETCH_NOP_SYMBOL;
256                         code->data = kstrdup(arg + 1, GFP_KERNEL);
257                         if (!code->data)
258                                 return -ENOMEM;
259                         if (++code == end)
260                                 return -E2BIG;
261
262                         code->op = FETCH_OP_IMM;
263                         code->immediate = 0;
264                 }
265                 /* These are fetching from memory */
266                 if (++code == end)
267                         return -E2BIG;
268                 *pcode = code;
269                 code->op = FETCH_OP_DEREF;
270                 code->offset = offset;
271                 break;
272
273         case '+':       /* deref memory */
274                 arg++;  /* Skip '+', because kstrtol() rejects it. */
275         case '-':
276                 tmp = strchr(arg, '(');
277                 if (!tmp)
278                         return -EINVAL;
279
280                 *tmp = '\0';
281                 ret = kstrtol(arg, 0, &offset);
282                 if (ret)
283                         break;
284
285                 arg = tmp + 1;
286                 tmp = strrchr(arg, ')');
287
288                 if (tmp) {
289                         const struct fetch_type *t2 = find_fetch_type(NULL);
290
291                         *tmp = '\0';
292                         ret = parse_probe_arg(arg, t2, &code, end, flags);
293                         if (ret)
294                                 break;
295                         if (code->op == FETCH_OP_COMM)
296                                 return -EINVAL;
297                         if (++code == end)
298                                 return -E2BIG;
299                         *pcode = code;
300
301                         code->op = FETCH_OP_DEREF;
302                         code->offset = offset;
303                 }
304                 break;
305         }
306         if (!ret && code->op == FETCH_OP_NOP) {
307                 /* Parsed, but do not find fetch method */
308                 ret = -EINVAL;
309         }
310         return ret;
311 }
312
313 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
314
315 /* Bitfield type needs to be parsed into a fetch function */
316 static int __parse_bitfield_probe_arg(const char *bf,
317                                       const struct fetch_type *t,
318                                       struct fetch_insn **pcode)
319 {
320         struct fetch_insn *code = *pcode;
321         unsigned long bw, bo;
322         char *tail;
323
324         if (*bf != 'b')
325                 return 0;
326
327         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
328
329         if (bw == 0 || *tail != '@')
330                 return -EINVAL;
331
332         bf = tail + 1;
333         bo = simple_strtoul(bf, &tail, 0);
334
335         if (tail == bf || *tail != '/')
336                 return -EINVAL;
337         code++;
338         if (code->op != FETCH_OP_NOP)
339                 return -E2BIG;
340         *pcode = code;
341
342         code->op = FETCH_OP_MOD_BF;
343         code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
344         code->rshift = BYTES_TO_BITS(t->size) - bw;
345         code->basesize = t->size;
346
347         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
348 }
349
350 /* String length checking wrapper */
351 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
352                 struct probe_arg *parg, unsigned int flags)
353 {
354         struct fetch_insn *code, *scode, *tmp = NULL;
355         char *t, *t2;
356         int ret, len;
357
358         if (strlen(arg) > MAX_ARGSTR_LEN) {
359                 pr_info("Argument is too long.: %s\n",  arg);
360                 return -ENOSPC;
361         }
362         parg->comm = kstrdup(arg, GFP_KERNEL);
363         if (!parg->comm) {
364                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
365                 return -ENOMEM;
366         }
367         t = strchr(arg, ':');
368         if (t) {
369                 *t = '\0';
370                 t2 = strchr(++t, '[');
371                 if (t2) {
372                         *t2 = '\0';
373                         parg->count = simple_strtoul(t2 + 1, &t2, 0);
374                         if (strcmp(t2, "]") || parg->count == 0)
375                                 return -EINVAL;
376                         if (parg->count > MAX_ARRAY_LEN)
377                                 return -E2BIG;
378                 }
379         }
380         /*
381          * The default type of $comm should be "string", and it can't be
382          * dereferenced.
383          */
384         if (!t && strcmp(arg, "$comm") == 0)
385                 parg->type = find_fetch_type("string");
386         else
387                 parg->type = find_fetch_type(t);
388         if (!parg->type) {
389                 pr_info("Unsupported type: %s\n", t);
390                 return -EINVAL;
391         }
392         parg->offset = *size;
393         *size += parg->type->size * (parg->count ?: 1);
394
395         if (parg->count) {
396                 len = strlen(parg->type->fmttype) + 6;
397                 parg->fmt = kmalloc(len, GFP_KERNEL);
398                 if (!parg->fmt)
399                         return -ENOMEM;
400                 snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
401                          parg->count);
402         }
403
404         code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
405         if (!code)
406                 return -ENOMEM;
407         code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
408
409         ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
410                               flags);
411         if (ret)
412                 goto fail;
413
414         /* Store operation */
415         if (!strcmp(parg->type->name, "string")) {
416                 if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM &&
417                     code->op != FETCH_OP_COMM) {
418                         pr_info("string only accepts memory or address.\n");
419                         ret = -EINVAL;
420                         goto fail;
421                 }
422                 if (code->op != FETCH_OP_DEREF || parg->count) {
423                         /*
424                          * IMM and COMM is pointing actual address, those must
425                          * be kept, and if parg->count != 0, this is an array
426                          * of string pointers instead of string address itself.
427                          */
428                         code++;
429                         if (code->op != FETCH_OP_NOP) {
430                                 ret = -E2BIG;
431                                 goto fail;
432                         }
433                 }
434                 code->op = FETCH_OP_ST_STRING;  /* In DEREF case, replace it */
435                 code->size = parg->type->size;
436                 parg->dynamic = true;
437         } else if (code->op == FETCH_OP_DEREF) {
438                 code->op = FETCH_OP_ST_MEM;
439                 code->size = parg->type->size;
440         } else {
441                 code++;
442                 if (code->op != FETCH_OP_NOP) {
443                         ret = -E2BIG;
444                         goto fail;
445                 }
446                 code->op = FETCH_OP_ST_RAW;
447                 code->size = parg->type->size;
448         }
449         scode = code;
450         /* Modify operation */
451         if (t != NULL) {
452                 ret = __parse_bitfield_probe_arg(t, parg->type, &code);
453                 if (ret)
454                         goto fail;
455         }
456         /* Loop(Array) operation */
457         if (parg->count) {
458                 if (scode->op != FETCH_OP_ST_MEM &&
459                     scode->op != FETCH_OP_ST_STRING) {
460                         pr_info("array only accepts memory or address\n");
461                         ret = -EINVAL;
462                         goto fail;
463                 }
464                 code++;
465                 if (code->op != FETCH_OP_NOP) {
466                         ret = -E2BIG;
467                         goto fail;
468                 }
469                 code->op = FETCH_OP_LP_ARRAY;
470                 code->param = parg->count;
471         }
472         code++;
473         code->op = FETCH_OP_END;
474
475         /* Shrink down the code buffer */
476         parg->code = kzalloc(sizeof(*code) * (code - tmp + 1), GFP_KERNEL);
477         if (!parg->code)
478                 ret = -ENOMEM;
479         else
480                 memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));
481
482 fail:
483         if (ret) {
484                 for (code = tmp; code < tmp + FETCH_INSN_MAX; code++)
485                         if (code->op == FETCH_NOP_SYMBOL)
486                                 kfree(code->data);
487         }
488         kfree(tmp);
489
490         return ret;
491 }
492
493 /* Return 1 if name is reserved or already used by another argument */
494 int traceprobe_conflict_field_name(const char *name,
495                                struct probe_arg *args, int narg)
496 {
497         int i;
498
499         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
500                 if (strcmp(reserved_field_names[i], name) == 0)
501                         return 1;
502
503         for (i = 0; i < narg; i++)
504                 if (strcmp(args[i].name, name) == 0)
505                         return 1;
506
507         return 0;
508 }
509
510 void traceprobe_free_probe_arg(struct probe_arg *arg)
511 {
512         struct fetch_insn *code = arg->code;
513
514         while (code && code->op != FETCH_OP_END) {
515                 if (code->op == FETCH_NOP_SYMBOL)
516                         kfree(code->data);
517                 code++;
518         }
519         kfree(arg->code);
520         kfree(arg->name);
521         kfree(arg->comm);
522         kfree(arg->fmt);
523 }
524
525 int traceprobe_update_arg(struct probe_arg *arg)
526 {
527         struct fetch_insn *code = arg->code;
528         long offset;
529         char *tmp;
530         char c;
531         int ret = 0;
532
533         while (code && code->op != FETCH_OP_END) {
534                 if (code->op == FETCH_NOP_SYMBOL) {
535                         if (code[1].op != FETCH_OP_IMM)
536                                 return -EINVAL;
537
538                         tmp = strpbrk("+-", code->data);
539                         if (tmp)
540                                 c = *tmp;
541                         ret = traceprobe_split_symbol_offset(code->data,
542                                                              &offset);
543                         if (ret)
544                                 return ret;
545
546                         code[1].immediate =
547                                 (unsigned long)kallsyms_lookup_name(code->data);
548                         if (tmp)
549                                 *tmp = c;
550                         if (!code[1].immediate)
551                                 return -ENOENT;
552                         code[1].immediate += offset;
553                 }
554                 code++;
555         }
556         return 0;
557 }
558
559 /* When len=0, we just calculate the needed length */
560 #define LEN_OR_ZERO (len ? len - pos : 0)
561 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
562                            bool is_return)
563 {
564         struct probe_arg *parg;
565         int i, j;
566         int pos = 0;
567         const char *fmt, *arg;
568
569         if (!is_return) {
570                 fmt = "(%lx)";
571                 arg = "REC->" FIELD_STRING_IP;
572         } else {
573                 fmt = "(%lx <- %lx)";
574                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
575         }
576
577         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
578
579         for (i = 0; i < tp->nr_args; i++) {
580                 parg = tp->args + i;
581                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=", parg->name);
582                 if (parg->count) {
583                         pos += snprintf(buf + pos, LEN_OR_ZERO, "{%s",
584                                         parg->type->fmt);
585                         for (j = 1; j < parg->count; j++)
586                                 pos += snprintf(buf + pos, LEN_OR_ZERO, ",%s",
587                                                 parg->type->fmt);
588                         pos += snprintf(buf + pos, LEN_OR_ZERO, "}");
589                 } else
590                         pos += snprintf(buf + pos, LEN_OR_ZERO, "%s",
591                                         parg->type->fmt);
592         }
593
594         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
595
596         for (i = 0; i < tp->nr_args; i++) {
597                 parg = tp->args + i;
598                 if (parg->count) {
599                         if (strcmp(parg->type->name, "string") == 0)
600                                 fmt = ", __get_str(%s[%d])";
601                         else
602                                 fmt = ", REC->%s[%d]";
603                         for (j = 0; j < parg->count; j++)
604                                 pos += snprintf(buf + pos, LEN_OR_ZERO,
605                                                 fmt, parg->name, j);
606                 } else {
607                         if (strcmp(parg->type->name, "string") == 0)
608                                 fmt = ", __get_str(%s)";
609                         else
610                                 fmt = ", REC->%s";
611                         pos += snprintf(buf + pos, LEN_OR_ZERO,
612                                         fmt, parg->name);
613                 }
614         }
615
616         /* return the length of print_fmt */
617         return pos;
618 }
619 #undef LEN_OR_ZERO
620
621 int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return)
622 {
623         int len;
624         char *print_fmt;
625
626         /* First: called with 0 length to calculate the needed length */
627         len = __set_print_fmt(tp, NULL, 0, is_return);
628         print_fmt = kmalloc(len + 1, GFP_KERNEL);
629         if (!print_fmt)
630                 return -ENOMEM;
631
632         /* Second: actually write the @print_fmt */
633         __set_print_fmt(tp, print_fmt, len + 1, is_return);
634         tp->call.print_fmt = print_fmt;
635
636         return 0;
637 }
638
639 int traceprobe_define_arg_fields(struct trace_event_call *event_call,
640                                  size_t offset, struct trace_probe *tp)
641 {
642         int ret, i;
643
644         /* Set argument names as fields */
645         for (i = 0; i < tp->nr_args; i++) {
646                 struct probe_arg *parg = &tp->args[i];
647                 const char *fmt = parg->type->fmttype;
648                 int size = parg->type->size;
649
650                 if (parg->fmt)
651                         fmt = parg->fmt;
652                 if (parg->count)
653                         size *= parg->count;
654                 ret = trace_define_field(event_call, fmt, parg->name,
655                                          offset + parg->offset, size,
656                                          parg->type->is_signed,
657                                          FILTER_OTHER);
658                 if (ret)
659                         return ret;
660         }
661         return 0;
662 }