1 // SPDX-License-Identifier: GPL-2.0-only 1
2 /*
3 * recordmcount.c: construct a table of the lo
4 * so that ftrace can find them quickly.
5 * Copyright 2009 John F. Reiser <jreiser@BitW
6 *
7 * Restructured to fit Linux format, as well a
8 * Copyright 2010 Steven Rostedt <srostedt@re
9 */
10
11 /*
12 * Strategy: alter the .o file in-place.
13 *
14 * Append a new STRTAB that has the new sectio
15 * ElfXX_Shdr[] that has the new section heade
16 * contents for __mcount_loc and its relocatio
17 * and the old ElfXX_Shdr[] array, remain as "
18 * kilobytes.) Subsequent processing by /bin/
19 * will ignore the garbage regions, because th
20 * new .e_shoff nor the new ElfXX_Shdr[]. [In
21 * then use "ld -r" to create a new file that
22 */
23
24 #include <sys/types.h>
25 #include <sys/mman.h>
26 #include <sys/stat.h>
27 #include <getopt.h>
28 #include <elf.h>
29 #include <fcntl.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <unistd.h>
34
35 #ifndef EM_AARCH64
36 #define EM_AARCH64 183
37 #define R_AARCH64_NONE 0
38 #define R_AARCH64_ABS64 257
39 #endif
40
41 #ifndef EM_LOONGARCH
42 #define EM_LOONGARCH 258
43 #define R_LARCH_32 1
44 #define R_LARCH_64 2
45 #define R_LARCH_MARK_LA 20
46 #define R_LARCH_SOP_PUSH_PLT_PCREL 29
47 #endif
48
49 #define R_ARM_PC24 1
50 #define R_ARM_THM_CALL 10
51 #define R_ARM_CALL 28
52
53 #define R_AARCH64_CALL26 283
54
55 static int fd_map; /* File descriptor for
56 static int mmap_failed; /* Boolean flag. */
57 static char gpfx; /* prefix for global s
58 static struct stat sb; /* Remember .st_size,
59 static const char *altmcount; /* alternate m
60 static int warn_on_notrace_sect; /* warn when
61 static void *file_map; /* pointer of the mapp
62 static void *file_end; /* pointer to the end
63 static int file_updated; /* flag to state file
64 static void *file_ptr; /* current file pointe
65
66 static void *file_append; /* added to the end
67 static size_t file_append_size; /* how much is
68
69 /* Per-file resource cleanup when multiple fil
70 static void file_append_cleanup(void)
71 {
72 free(file_append);
73 file_append = NULL;
74 file_append_size = 0;
75 file_updated = 0;
76 }
77
78 static void mmap_cleanup(void)
79 {
80 if (!mmap_failed)
81 munmap(file_map, sb.st_size);
82 else
83 free(file_map);
84 file_map = NULL;
85 }
86
87 /* ulseek, uwrite, ...: Check return value fo
88
89 static off_t ulseek(off_t const offset, int co
90 {
91 switch (whence) {
92 case SEEK_SET:
93 file_ptr = file_map + offset;
94 break;
95 case SEEK_CUR:
96 file_ptr += offset;
97 break;
98 case SEEK_END:
99 file_ptr = file_map + (sb.st_s
100 break;
101 }
102 if (file_ptr < file_map) {
103 fprintf(stderr, "lseek: seek b
104 return -1;
105 }
106 return file_ptr - file_map;
107 }
108
109 static ssize_t uwrite(void const *const buf, s
110 {
111 size_t cnt = count;
112 off_t idx = 0;
113 void *p = NULL;
114
115 file_updated = 1;
116
117 if (file_ptr + count >= file_end) {
118 off_t aoffset = (file_ptr + co
119
120 if (aoffset > file_append_size
121 p = realloc(file_appen
122 if (!p)
123 free(file_appe
124 file_append = p;
125 file_append_size = aof
126 }
127 if (!file_append) {
128 perror("write");
129 file_append_cleanup();
130 mmap_cleanup();
131 return -1;
132 }
133 if (file_ptr < file_end) {
134 cnt = file_end - file_
135 } else {
136 cnt = 0;
137 idx = aoffset - count;
138 }
139 }
140
141 if (cnt)
142 memcpy(file_ptr, buf, cnt);
143
144 if (cnt < count)
145 memcpy(file_append + idx, buf
146
147 file_ptr += count;
148 return count;
149 }
150
151 static void * umalloc(size_t size)
152 {
153 void *const addr = malloc(size);
154 if (addr == 0) {
155 fprintf(stderr, "malloc failed
156 file_append_cleanup();
157 mmap_cleanup();
158 return NULL;
159 }
160 return addr;
161 }
162
163 /*
164 * Get the whole file as a programming conveni
165 * malloc+lseek+read+free of many pieces. If
166 * avoids copying unused pieces; else just rea
167 * Open for both read and write; new info will
168 * Use MAP_PRIVATE so that a few changes to th
169 * do not propagate to the file until an expli
170 * This preserves most aspects of consistency
171 * for simultaneous readers of the file while
172 * However, multiple writers still are bad. W
173 * locking because it is expensive and the use
174 * makes multiple writers unlikely.
175 */
176 static void *mmap_file(char const *fname)
177 {
178 /* Avoid problems if early cleanup() *
179 fd_map = -1;
180 mmap_failed = 1;
181 file_map = NULL;
182 file_ptr = NULL;
183 file_updated = 0;
184 sb.st_size = 0;
185
186 fd_map = open(fname, O_RDONLY);
187 if (fd_map < 0) {
188 perror(fname);
189 return NULL;
190 }
191 if (fstat(fd_map, &sb) < 0) {
192 perror(fname);
193 goto out;
194 }
195 if (!S_ISREG(sb.st_mode)) {
196 fprintf(stderr, "not a regular
197 goto out;
198 }
199 file_map = mmap(0, sb.st_size, PROT_RE
200 fd_map, 0);
201 if (file_map == MAP_FAILED) {
202 mmap_failed = 1;
203 file_map = umalloc(sb.st_size)
204 if (!file_map) {
205 perror(fname);
206 goto out;
207 }
208 if (read(fd_map, file_map, sb.
209 perror(fname);
210 free(file_map);
211 file_map = NULL;
212 goto out;
213 }
214 } else
215 mmap_failed = 0;
216 out:
217 close(fd_map);
218 fd_map = -1;
219
220 file_end = file_map + sb.st_size;
221
222 return file_map;
223 }
224
225
226 static unsigned char ideal_nop5_x86_64[5] = {
227 static unsigned char ideal_nop5_x86_32[5] = {
228 static unsigned char *ideal_nop;
229
230 static char rel_type_nop;
231
232 static int (*make_nop)(void *map, size_t const
233
234 static int make_nop_x86(void *map, size_t cons
235 {
236 uint32_t *ptr;
237 unsigned char *op;
238
239 /* Confirm we have 0xe8 0x0 0x0 0x0 0x
240 ptr = map + offset;
241 if (*ptr != 0)
242 return -1;
243
244 op = map + offset - 1;
245 if (*op != 0xe8)
246 return -1;
247
248 /* convert to nop */
249 if (ulseek(offset - 1, SEEK_SET) < 0)
250 return -1;
251 if (uwrite(ideal_nop, 5) < 0)
252 return -1;
253 return 0;
254 }
255
256 static unsigned char ideal_nop4_arm_le[4] = {
257 static unsigned char ideal_nop4_arm_be[4] = {
258 static unsigned char *ideal_nop4_arm;
259
260 static unsigned char bl_mcount_arm_le[4] = { 0
261 static unsigned char bl_mcount_arm_be[4] = { 0
262 static unsigned char *bl_mcount_arm;
263
264 static unsigned char push_arm_le[4] = { 0x04,
265 static unsigned char push_arm_be[4] = { 0xe5,
266 static unsigned char *push_arm;
267
268 static unsigned char ideal_nop2_thumb_le[2] =
269 static unsigned char ideal_nop2_thumb_be[2] =
270 static unsigned char *ideal_nop2_thumb;
271
272 static unsigned char push_bl_mcount_thumb_le[6
273 static unsigned char push_bl_mcount_thumb_be[6
274 static unsigned char *push_bl_mcount_thumb;
275
276 static int make_nop_arm(void *map, size_t cons
277 {
278 char *ptr;
279 int cnt = 1;
280 int nop_size;
281 size_t off = offset;
282
283 ptr = map + offset;
284 if (memcmp(ptr, bl_mcount_arm, 4) == 0
285 if (memcmp(ptr - 4, push_arm,
286 off -= 4;
287 cnt = 2;
288 }
289 ideal_nop = ideal_nop4_arm;
290 nop_size = 4;
291 } else if (memcmp(ptr - 2, push_bl_mco
292 cnt = 3;
293 nop_size = 2;
294 off -= 2;
295 ideal_nop = ideal_nop2_thumb;
296 } else
297 return -1;
298
299 /* Convert to nop */
300 if (ulseek(off, SEEK_SET) < 0)
301 return -1;
302
303 do {
304 if (uwrite(ideal_nop, nop_size
305 return -1;
306 } while (--cnt > 0);
307
308 return 0;
309 }
310
311 static unsigned char ideal_nop4_arm64[4] = {0x
312 static int make_nop_arm64(void *map, size_t co
313 {
314 uint32_t *ptr;
315
316 ptr = map + offset;
317 /* bl <_mcount> is 0x94000000 before r
318 if (*ptr != 0x94000000)
319 return -1;
320
321 /* Convert to nop */
322 if (ulseek(offset, SEEK_SET) < 0)
323 return -1;
324 if (uwrite(ideal_nop, 4) < 0)
325 return -1;
326 return 0;
327 }
328
329 static int write_file(const char *fname)
330 {
331 char tmp_file[strlen(fname) + 4];
332 size_t n;
333
334 if (!file_updated)
335 return 0;
336
337 sprintf(tmp_file, "%s.rc", fname);
338
339 /*
340 * After reading the entire file into
341 * and write it back, to prevent weird
342 * an object file in place.
343 */
344 fd_map = open(tmp_file, O_WRONLY | O_T
345 if (fd_map < 0) {
346 perror(fname);
347 return -1;
348 }
349 n = write(fd_map, file_map, sb.st_size
350 if (n != sb.st_size) {
351 perror("write");
352 close(fd_map);
353 return -1;
354 }
355 if (file_append_size) {
356 n = write(fd_map, file_append,
357 if (n != file_append_size) {
358 perror("write");
359 close(fd_map);
360 return -1;
361 }
362 }
363 close(fd_map);
364 if (rename(tmp_file, fname) < 0) {
365 perror(fname);
366 return -1;
367 }
368 return 0;
369 }
370
371 /* w8rev, w8nat, ...: Handle endianness. */
372
373 static uint64_t w8rev(uint64_t const x)
374 {
375 return ((0xff & (x >> (0 * 8))) << (
376 | ((0xff & (x >> (1 * 8))) << (
377 | ((0xff & (x >> (2 * 8))) << (
378 | ((0xff & (x >> (3 * 8))) << (
379 | ((0xff & (x >> (4 * 8))) << (
380 | ((0xff & (x >> (5 * 8))) << (
381 | ((0xff & (x >> (6 * 8))) << (
382 | ((0xff & (x >> (7 * 8))) << (
383 }
384
385 static uint32_t w4rev(uint32_t const x)
386 {
387 return ((0xff & (x >> (0 * 8))) << (
388 | ((0xff & (x >> (1 * 8))) << (
389 | ((0xff & (x >> (2 * 8))) << (
390 | ((0xff & (x >> (3 * 8))) << (
391 }
392
393 static uint32_t w2rev(uint16_t const x)
394 {
395 return ((0xff & (x >> (0 * 8))) << (
396 | ((0xff & (x >> (1 * 8))) << (
397 }
398
399 static uint64_t w8nat(uint64_t const x)
400 {
401 return x;
402 }
403
404 static uint32_t w4nat(uint32_t const x)
405 {
406 return x;
407 }
408
409 static uint32_t w2nat(uint16_t const x)
410 {
411 return x;
412 }
413
414 static uint64_t (*w8)(uint64_t);
415 static uint32_t (*w)(uint32_t);
416 static uint32_t (*w2)(uint16_t);
417
418 /* Names of the sections that could contain ca
419 static int is_mcounted_section_name(char const
420 {
421 return strncmp(".text", txtna
422 strcmp(".init.text", txtna
423 strcmp(".ref.text", txtna
424 strcmp(".sched.text", txtna
425 strcmp(".spinlock.text", txtna
426 strcmp(".irqentry.text", txtna
427 strcmp(".softirqentry.text", t
428 strcmp(".kprobes.text", txtnam
429 strcmp(".cpuidle.text", txtnam
430 }
431
432 static char const *already_has_rel_mcount = "s
433
434 /* 32 bit and 64 bit are very similar */
435 #include "recordmcount.h"
436 #define RECORD_MCOUNT_64
437 #include "recordmcount.h"
438
439 static int arm_is_fake_mcount(Elf32_Rel const
440 {
441 switch (ELF32_R_TYPE(w(rp->r_info))) {
442 case R_ARM_THM_CALL:
443 case R_ARM_CALL:
444 case R_ARM_PC24:
445 return 0;
446 }
447
448 return 1;
449 }
450
451 static int arm64_is_fake_mcount(Elf64_Rel cons
452 {
453 return ELF64_R_TYPE(w8(rp->r_info)) !=
454 }
455
456 static int LARCH32_is_fake_mcount(Elf32_Rel co
457 {
458 switch (ELF64_R_TYPE(w(rp->r_info))) {
459 case R_LARCH_MARK_LA:
460 case R_LARCH_SOP_PUSH_PLT_PCREL:
461 return 0;
462 }
463
464 return 1;
465 }
466
467 static int LARCH64_is_fake_mcount(Elf64_Rel co
468 {
469 switch (ELF64_R_TYPE(w(rp->r_info))) {
470 case R_LARCH_MARK_LA:
471 case R_LARCH_SOP_PUSH_PLT_PCREL:
472 return 0;
473 }
474
475 return 1;
476 }
477
478 /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
479 * http://techpubs.sgi.com/library/manuals/400
480 * We interpret Table 29 Relocation Operation
481 * to imply the order of the members; the spec
482 * typedef unsigned char Elf64_Byte;
483 * fails on MIPS64 because their <elf.h> alrea
484 */
485
486 typedef uint8_t myElf64_Byte; /* Typ
487
488 union mips_r_info {
489 Elf64_Xword r_info;
490 struct {
491 Elf64_Word r_sym;
492 myElf64_Byte r_ssym;
493 myElf64_Byte r_type3;
494 myElf64_Byte r_type2;
495 myElf64_Byte r_type;
496 } r_mips;
497 };
498
499 static uint64_t MIPS64_r_sym(Elf64_Rel const *
500 {
501 return w(((union mips_r_info){ .r_info
502 }
503
504 static void MIPS64_r_info(Elf64_Rel *const rp,
505 {
506 rp->r_info = ((union mips_r_info){
507 .r_mips = { .r_sym = w(sym), .
508 }).r_info;
509 }
510
511 static int do_file(char const *const fname)
512 {
513 unsigned int reltype = 0;
514 Elf32_Ehdr *ehdr;
515 int rc = -1;
516
517 ehdr = mmap_file(fname);
518 if (!ehdr)
519 goto out;
520
521 w = w4nat;
522 w2 = w2nat;
523 w8 = w8nat;
524 switch (ehdr->e_ident[EI_DATA]) {
525 static unsigned int const endi
526 default:
527 fprintf(stderr, "unrecognized
528 ehdr->e_ident[EI_DATA]
529 goto out;
530 case ELFDATA2LSB:
531 if (*(unsigned char const *)&e
532 /* main() is big endia
533 w = w4rev;
534 w2 = w2rev;
535 w8 = w8rev;
536 }
537 ideal_nop4_arm = ideal_nop4_ar
538 bl_mcount_arm = bl_mcount_arm_
539 push_arm = push_arm_le;
540 ideal_nop2_thumb = ideal_nop2_
541 push_bl_mcount_thumb = push_bl
542 break;
543 case ELFDATA2MSB:
544 if (*(unsigned char const *)&e
545 /* main() is little en
546 w = w4rev;
547 w2 = w2rev;
548 w8 = w8rev;
549 }
550 ideal_nop4_arm = ideal_nop4_ar
551 bl_mcount_arm = bl_mcount_arm_
552 push_arm = push_arm_be;
553 ideal_nop2_thumb = ideal_nop2_
554 push_bl_mcount_thumb = push_bl
555 break;
556 } /* end switch */
557 if (memcmp(ELFMAG, ehdr->e_ident, SELF
558 w2(ehdr->e_type) != ET_REL ||
559 ehdr->e_ident[EI_VERSION] != EV_CU
560 fprintf(stderr, "unrecognized
561 goto out;
562 }
563
564 gpfx = '_';
565 switch (w2(ehdr->e_machine)) {
566 default:
567 fprintf(stderr, "unrecognized
568 w2(ehdr->e_machine), f
569 goto out;
570 case EM_386:
571 reltype = R_386_32;
572 rel_type_nop = R_386_NONE;
573 make_nop = make_nop_x86;
574 ideal_nop = ideal_nop5_x86_32;
575 mcount_adjust_32 = -1;
576 gpfx = 0;
577 break;
578 case EM_ARM:
579 reltype = R_ARM_ABS32;
580 altmcount = "__gnu_mcount_nc";
581 make_nop = make_nop_arm;
582 rel_type_nop = R_ARM_NONE;
583 is_fake_mcount32 = arm_is_fake
584 gpfx = 0;
585 break;
586 case EM_AARCH64:
587 reltype = R_AARCH64_ABS64;
588 make_nop = make_nop_arm64;
589 rel_type_nop = R_AARCH64_NONE;
590 ideal_nop = ideal_nop4_arm64;
591 is_fake_mcount64 = arm64_is_fa
592 break;
593 case EM_MIPS: /* reltype: e_class
594 case EM_LOONGARCH: /* reltype: e_
595 case EM_PPC: reltype = R_PPC_ADDR32
596 case EM_PPC64: reltype = R_PPC64_ADDR
597 case EM_S390: /* reltype: e_class
598 case EM_SH: reltype = R_SH_DIR32;
599 case EM_SPARCV9: reltype = R_SPARC_64;
600 case EM_X86_64:
601 make_nop = make_nop_x86;
602 ideal_nop = ideal_nop5_x86_64;
603 reltype = R_X86_64_64;
604 rel_type_nop = R_X86_64_NONE;
605 mcount_adjust_64 = -1;
606 gpfx = 0;
607 break;
608 } /* end switch */
609
610 switch (ehdr->e_ident[EI_CLASS]) {
611 default:
612 fprintf(stderr, "unrecognized
613 ehdr->e_ident[EI_CLASS
614 goto out;
615 case ELFCLASS32:
616 if (w2(ehdr->e_ehsize) != size
617 || w2(ehdr->e_shentsize) != s
618 fprintf(stderr,
619 "unrecognized
620 goto out;
621 }
622 if (w2(ehdr->e_machine) == EM_
623 reltype = R_MIPS_32;
624 is_fake_mcount32 = MIP
625 }
626 if (w2(ehdr->e_machine) == EM_
627 reltype = R_LARCH_32;
628 is_fake_mcount32 = LAR
629 }
630 if (do32(ehdr, fname, reltype)
631 goto out;
632 break;
633 case ELFCLASS64: {
634 Elf64_Ehdr *const ghdr = (Elf6
635 if (w2(ghdr->e_ehsize) != size
636 || w2(ghdr->e_shentsize) != s
637 fprintf(stderr,
638 "unrecognized
639 goto out;
640 }
641 if (w2(ghdr->e_machine) == EM_
642 reltype = R_390_64;
643 mcount_adjust_64 = -14
644 }
645 if (w2(ghdr->e_machine) == EM_
646 reltype = R_MIPS_64;
647 Elf64_r_sym = MIPS64_r
648 Elf64_r_info = MIPS64_
649 is_fake_mcount64 = MIP
650 }
651 if (w2(ghdr->e_machine) == EM_
652 reltype = R_LARCH_64;
653 is_fake_mcount64 = LAR
654 }
655 if (do64(ghdr, fname, reltype)
656 goto out;
657 break;
658 }
659 } /* end switch */
660
661 rc = write_file(fname);
662 out:
663 file_append_cleanup();
664 mmap_cleanup();
665 return rc;
666 }
667
668 int main(int argc, char *argv[])
669 {
670 const char ftrace[] = "/ftrace.o";
671 int ftrace_size = sizeof(ftrace) - 1;
672 int n_error = 0; /* gcc-4.3.0 false p
673 int c;
674 int i;
675
676 while ((c = getopt(argc, argv, "w")) >
677 switch (c) {
678 case 'w':
679 warn_on_notrace_sect =
680 break;
681 default:
682 fprintf(stderr, "usage
683 return 0;
684 }
685 }
686
687 if ((argc - optind) < 1) {
688 fprintf(stderr, "usage: record
689 return 0;
690 }
691
692 /* Process each file in turn, allowing
693 for (i = optind; i < argc; i++) {
694 char *file = argv[i];
695 int len;
696
697 /*
698 * The file kernel/trace/ftrac
699 * function but does not call
700 * not be traced anyway, we ju
701 */
702 len = strlen(file);
703 if (len >= ftrace_size &&
704 strcmp(file + (len - ftrac
705 continue;
706
707 if (do_file(file)) {
708 fprintf(stderr, "%s: f
709 ++n_error;
710 }
711 }
712 return !!n_error;
713 }
714
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