xref: /openbmc/linux/scripts/recordmcount.c (revision fa359d06)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * recordmcount.c: construct a table of the locations of calls to 'mcount'
4  * so that ftrace can find them quickly.
5  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
6  *
7  * Restructured to fit Linux format, as well as other updates:
8  *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
9  */
10 
11 /*
12  * Strategy: alter the .o file in-place.
13  *
14  * Append a new STRTAB that has the new section names, followed by a new array
15  * ElfXX_Shdr[] that has the new section headers, followed by the section
16  * contents for __mcount_loc and its relocations.  The old shstrtab strings,
17  * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple
18  * kilobytes.)  Subsequent processing by /bin/ld (or the kernel module loader)
19  * will ignore the garbage regions, because they are not designated by the
20  * new .e_shoff nor the new ElfXX_Shdr[].  [In order to remove the garbage,
21  * then use "ld -r" to create a new file that omits the garbage.]
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 file being modified. */
56 static int mmap_failed; /* Boolean flag. */
57 static char gpfx;	/* prefix for global symbol name (sometimes '_') */
58 static struct stat sb;	/* Remember .st_size, etc. */
59 static const char *altmcount;	/* alternate mcount symbol name */
60 static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
61 static void *file_map;	/* pointer of the mapped file */
62 static void *file_end;	/* pointer to the end of the mapped file */
63 static int file_updated; /* flag to state file was changed */
64 static void *file_ptr;	/* current file pointer location */
65 
66 static void *file_append; /* added to the end of the file */
67 static size_t file_append_size; /* how much is added to end of file */
68 
69 /* Per-file resource cleanup when multiple files. */
file_append_cleanup(void)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 
mmap_cleanup(void)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 for errors. */
88 
ulseek(off_t const offset,int const whence)89 static off_t ulseek(off_t const offset, int const whence)
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_size - offset);
100 		break;
101 	}
102 	if (file_ptr < file_map) {
103 		fprintf(stderr, "lseek: seek before file\n");
104 		return -1;
105 	}
106 	return file_ptr - file_map;
107 }
108 
uwrite(void const * const buf,size_t const count)109 static ssize_t uwrite(void const *const buf, size_t const count)
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 + count) - file_end;
119 
120 		if (aoffset > file_append_size) {
121 			p = realloc(file_append, aoffset);
122 			if (!p)
123 				free(file_append);
124 			file_append = p;
125 			file_append_size = aoffset;
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_ptr;
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 + cnt, count - cnt);
146 
147 	file_ptr += count;
148 	return count;
149 }
150 
umalloc(size_t size)151 static void * umalloc(size_t size)
152 {
153 	void *const addr = malloc(size);
154 	if (addr == 0) {
155 		fprintf(stderr, "malloc failed: %zu bytes\n", size);
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 convenience in order to avoid
165  * malloc+lseek+read+free of many pieces.  If successful, then mmap
166  * avoids copying unused pieces; else just read the whole file.
167  * Open for both read and write; new info will be appended to the file.
168  * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
169  * do not propagate to the file until an explicit overwrite at the last.
170  * This preserves most aspects of consistency (all except .st_size)
171  * for simultaneous readers of the file while we are appending to it.
172  * However, multiple writers still are bad.  We choose not to use
173  * locking because it is expensive and the use case of kernel build
174  * makes multiple writers unlikely.
175  */
mmap_file(char const * fname)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 file: %s\n", fname);
197 		goto out;
198 	}
199 	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
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.st_size) != sb.st_size) {
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] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
227 static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
228 static unsigned char *ideal_nop;
229 
230 static char rel_type_nop;
231 
232 static int (*make_nop)(void *map, size_t const offset);
233 
make_nop_x86(void * map,size_t const offset)234 static int make_nop_x86(void *map, size_t const offset)
235 {
236 	uint32_t *ptr;
237 	unsigned char *op;
238 
239 	/* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
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] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */
257 static unsigned char ideal_nop4_arm_be[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */
258 static unsigned char *ideal_nop4_arm;
259 
260 static unsigned char bl_mcount_arm_le[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */
261 static unsigned char bl_mcount_arm_be[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */
262 static unsigned char *bl_mcount_arm;
263 
264 static unsigned char push_arm_le[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */
265 static unsigned char push_arm_be[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */
266 static unsigned char *push_arm;
267 
268 static unsigned char ideal_nop2_thumb_le[2] = { 0x00, 0xbf }; /* nop */
269 static unsigned char ideal_nop2_thumb_be[2] = { 0xbf, 0x00 }; /* nop */
270 static unsigned char *ideal_nop2_thumb;
271 
272 static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */
273 static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */
274 static unsigned char *push_bl_mcount_thumb;
275 
make_nop_arm(void * map,size_t const offset)276 static int make_nop_arm(void *map, size_t const offset)
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, 4) == 0) {
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_mcount_thumb, 6) == 0) {
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) < 0)
305 			return -1;
306 	} while (--cnt > 0);
307 
308 	return 0;
309 }
310 
311 static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};
make_nop_arm64(void * map,size_t const offset)312 static int make_nop_arm64(void *map, size_t const offset)
313 {
314 	uint32_t *ptr;
315 
316 	ptr = map + offset;
317 	/* bl <_mcount> is 0x94000000 before relocation */
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 
write_file(const char * fname)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 memory, delete it
341 	 * and write it back, to prevent weird side effects of modifying
342 	 * an object file in place.
343 	 */
344 	fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
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, file_append_size);
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 
w8rev(uint64_t const x)373 static uint64_t w8rev(uint64_t const x)
374 {
375 	return   ((0xff & (x >> (0 * 8))) << (7 * 8))
376 	       | ((0xff & (x >> (1 * 8))) << (6 * 8))
377 	       | ((0xff & (x >> (2 * 8))) << (5 * 8))
378 	       | ((0xff & (x >> (3 * 8))) << (4 * 8))
379 	       | ((0xff & (x >> (4 * 8))) << (3 * 8))
380 	       | ((0xff & (x >> (5 * 8))) << (2 * 8))
381 	       | ((0xff & (x >> (6 * 8))) << (1 * 8))
382 	       | ((0xff & (x >> (7 * 8))) << (0 * 8));
383 }
384 
w4rev(uint32_t const x)385 static uint32_t w4rev(uint32_t const x)
386 {
387 	return   ((0xff & (x >> (0 * 8))) << (3 * 8))
388 	       | ((0xff & (x >> (1 * 8))) << (2 * 8))
389 	       | ((0xff & (x >> (2 * 8))) << (1 * 8))
390 	       | ((0xff & (x >> (3 * 8))) << (0 * 8));
391 }
392 
w2rev(uint16_t const x)393 static uint32_t w2rev(uint16_t const x)
394 {
395 	return   ((0xff & (x >> (0 * 8))) << (1 * 8))
396 	       | ((0xff & (x >> (1 * 8))) << (0 * 8));
397 }
398 
w8nat(uint64_t const x)399 static uint64_t w8nat(uint64_t const x)
400 {
401 	return x;
402 }
403 
w4nat(uint32_t const x)404 static uint32_t w4nat(uint32_t const x)
405 {
406 	return x;
407 }
408 
w2nat(uint16_t const x)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 calls to mcount. */
is_mcounted_section_name(char const * const txtname)419 static int is_mcounted_section_name(char const *const txtname)
420 {
421 	return strncmp(".text",          txtname, 5) == 0 ||
422 		strcmp(".init.text",     txtname) == 0 ||
423 		strcmp(".ref.text",      txtname) == 0 ||
424 		strcmp(".sched.text",    txtname) == 0 ||
425 		strcmp(".spinlock.text", txtname) == 0 ||
426 		strcmp(".irqentry.text", txtname) == 0 ||
427 		strcmp(".softirqentry.text", txtname) == 0 ||
428 		strcmp(".kprobes.text", txtname) == 0 ||
429 		strcmp(".cpuidle.text", txtname) == 0;
430 }
431 
432 static char const *already_has_rel_mcount = "success"; /* our work here is done! */
433 
434 /* 32 bit and 64 bit are very similar */
435 #include "recordmcount.h"
436 #define RECORD_MCOUNT_64
437 #include "recordmcount.h"
438 
arm_is_fake_mcount(Elf32_Rel const * rp)439 static int arm_is_fake_mcount(Elf32_Rel const *rp)
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 
arm64_is_fake_mcount(Elf64_Rel const * rp)451 static int arm64_is_fake_mcount(Elf64_Rel const *rp)
452 {
453 	return ELF64_R_TYPE(w8(rp->r_info)) != R_AARCH64_CALL26;
454 }
455 
LARCH32_is_fake_mcount(Elf32_Rel const * rp)456 static int LARCH32_is_fake_mcount(Elf32_Rel const *rp)
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 
LARCH64_is_fake_mcount(Elf64_Rel const * rp)467 static int LARCH64_is_fake_mcount(Elf64_Rel const *rp)
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/4000/007-4658-001/pdf/007-4658-001.pdf
480  * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
481  * to imply the order of the members; the spec does not say so.
482  *	typedef unsigned char Elf64_Byte;
483  * fails on MIPS64 because their <elf.h> already has it!
484  */
485 
486 typedef uint8_t myElf64_Byte;		/* Type for a 8-bit quantity.  */
487 
488 union mips_r_info {
489 	Elf64_Xword r_info;
490 	struct {
491 		Elf64_Word r_sym;		/* Symbol index.  */
492 		myElf64_Byte r_ssym;		/* Special symbol.  */
493 		myElf64_Byte r_type3;		/* Third relocation.  */
494 		myElf64_Byte r_type2;		/* Second relocation.  */
495 		myElf64_Byte r_type;		/* First relocation.  */
496 	} r_mips;
497 };
498 
MIPS64_r_sym(Elf64_Rel const * rp)499 static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
500 {
501 	return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
502 }
503 
MIPS64_r_info(Elf64_Rel * const rp,unsigned sym,unsigned type)504 static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
505 {
506 	rp->r_info = ((union mips_r_info){
507 		.r_mips = { .r_sym = w(sym), .r_type = type }
508 	}).r_info;
509 }
510 
do_file(char const * const fname)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 endian = 1;
526 	default:
527 		fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
528 			ehdr->e_ident[EI_DATA], fname);
529 		goto out;
530 	case ELFDATA2LSB:
531 		if (*(unsigned char const *)&endian != 1) {
532 			/* main() is big endian, file.o is little endian. */
533 			w = w4rev;
534 			w2 = w2rev;
535 			w8 = w8rev;
536 		}
537 		ideal_nop4_arm = ideal_nop4_arm_le;
538 		bl_mcount_arm = bl_mcount_arm_le;
539 		push_arm = push_arm_le;
540 		ideal_nop2_thumb = ideal_nop2_thumb_le;
541 		push_bl_mcount_thumb = push_bl_mcount_thumb_le;
542 		break;
543 	case ELFDATA2MSB:
544 		if (*(unsigned char const *)&endian != 0) {
545 			/* main() is little endian, file.o is big endian. */
546 			w = w4rev;
547 			w2 = w2rev;
548 			w8 = w8rev;
549 		}
550 		ideal_nop4_arm = ideal_nop4_arm_be;
551 		bl_mcount_arm = bl_mcount_arm_be;
552 		push_arm = push_arm_be;
553 		ideal_nop2_thumb = ideal_nop2_thumb_be;
554 		push_bl_mcount_thumb = push_bl_mcount_thumb_be;
555 		break;
556 	}  /* end switch */
557 	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 ||
558 	    w2(ehdr->e_type) != ET_REL ||
559 	    ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
560 		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
561 		goto out;
562 	}
563 
564 	gpfx = '_';
565 	switch (w2(ehdr->e_machine)) {
566 	default:
567 		fprintf(stderr, "unrecognized e_machine %u %s\n",
568 			w2(ehdr->e_machine), fname);
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_mcount;
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_fake_mcount;
592 		break;
593 	case EM_IA_64:	reltype = R_IA64_IMM64; break;
594 	case EM_MIPS:	/* reltype: e_class    */ break;
595 	case EM_LOONGARCH:	/* reltype: e_class    */ break;
596 	case EM_PPC:	reltype = R_PPC_ADDR32; break;
597 	case EM_PPC64:	reltype = R_PPC64_ADDR64; break;
598 	case EM_S390:	/* reltype: e_class    */ break;
599 	case EM_SH:	reltype = R_SH_DIR32; gpfx = 0; break;
600 	case EM_SPARCV9: reltype = R_SPARC_64; break;
601 	case EM_X86_64:
602 		make_nop = make_nop_x86;
603 		ideal_nop = ideal_nop5_x86_64;
604 		reltype = R_X86_64_64;
605 		rel_type_nop = R_X86_64_NONE;
606 		mcount_adjust_64 = -1;
607 		gpfx = 0;
608 		break;
609 	}  /* end switch */
610 
611 	switch (ehdr->e_ident[EI_CLASS]) {
612 	default:
613 		fprintf(stderr, "unrecognized ELF class %d %s\n",
614 			ehdr->e_ident[EI_CLASS], fname);
615 		goto out;
616 	case ELFCLASS32:
617 		if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
618 		||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
619 			fprintf(stderr,
620 				"unrecognized ET_REL file: %s\n", fname);
621 			goto out;
622 		}
623 		if (w2(ehdr->e_machine) == EM_MIPS) {
624 			reltype = R_MIPS_32;
625 			is_fake_mcount32 = MIPS32_is_fake_mcount;
626 		}
627 		if (w2(ehdr->e_machine) == EM_LOONGARCH) {
628 			reltype = R_LARCH_32;
629 			is_fake_mcount32 = LARCH32_is_fake_mcount;
630 		}
631 		if (do32(ehdr, fname, reltype) < 0)
632 			goto out;
633 		break;
634 	case ELFCLASS64: {
635 		Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
636 		if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
637 		||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
638 			fprintf(stderr,
639 				"unrecognized ET_REL file: %s\n", fname);
640 			goto out;
641 		}
642 		if (w2(ghdr->e_machine) == EM_S390) {
643 			reltype = R_390_64;
644 			mcount_adjust_64 = -14;
645 		}
646 		if (w2(ghdr->e_machine) == EM_MIPS) {
647 			reltype = R_MIPS_64;
648 			Elf64_r_sym = MIPS64_r_sym;
649 			Elf64_r_info = MIPS64_r_info;
650 			is_fake_mcount64 = MIPS64_is_fake_mcount;
651 		}
652 		if (w2(ghdr->e_machine) == EM_LOONGARCH) {
653 			reltype = R_LARCH_64;
654 			is_fake_mcount64 = LARCH64_is_fake_mcount;
655 		}
656 		if (do64(ghdr, fname, reltype) < 0)
657 			goto out;
658 		break;
659 	}
660 	}  /* end switch */
661 
662 	rc = write_file(fname);
663 out:
664 	file_append_cleanup();
665 	mmap_cleanup();
666 	return rc;
667 }
668 
main(int argc,char * argv[])669 int main(int argc, char *argv[])
670 {
671 	const char ftrace[] = "/ftrace.o";
672 	int ftrace_size = sizeof(ftrace) - 1;
673 	int n_error = 0;  /* gcc-4.3.0 false positive complaint */
674 	int c;
675 	int i;
676 
677 	while ((c = getopt(argc, argv, "w")) >= 0) {
678 		switch (c) {
679 		case 'w':
680 			warn_on_notrace_sect = 1;
681 			break;
682 		default:
683 			fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
684 			return 0;
685 		}
686 	}
687 
688 	if ((argc - optind) < 1) {
689 		fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
690 		return 0;
691 	}
692 
693 	/* Process each file in turn, allowing deep failure. */
694 	for (i = optind; i < argc; i++) {
695 		char *file = argv[i];
696 		int len;
697 
698 		/*
699 		 * The file kernel/trace/ftrace.o references the mcount
700 		 * function but does not call it. Since ftrace.o should
701 		 * not be traced anyway, we just skip it.
702 		 */
703 		len = strlen(file);
704 		if (len >= ftrace_size &&
705 		    strcmp(file + (len - ftrace_size), ftrace) == 0)
706 			continue;
707 
708 		if (do_file(file)) {
709 			fprintf(stderr, "%s: failed\n", file);
710 			++n_error;
711 		}
712 	}
713 	return !!n_error;
714 }
715