xref: /linux/scripts/recordmcount.c (revision 06d07429858317ded2db7986113a9e0129cd599b)
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_MIPS:	/* reltype: e_class    */ break;
594  	case EM_LOONGARCH:	/* reltype: e_class    */ break;
595  	case EM_PPC:	reltype = R_PPC_ADDR32; break;
596  	case EM_PPC64:	reltype = R_PPC64_ADDR64; break;
597  	case EM_S390:	/* reltype: e_class    */ break;
598  	case EM_SH:	reltype = R_SH_DIR32; gpfx = 0; break;
599  	case EM_SPARCV9: reltype = R_SPARC_64; break;
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 ELF class %d %s\n",
613  			ehdr->e_ident[EI_CLASS], fname);
614  		goto out;
615  	case ELFCLASS32:
616  		if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
617  		||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
618  			fprintf(stderr,
619  				"unrecognized ET_REL file: %s\n", fname);
620  			goto out;
621  		}
622  		if (w2(ehdr->e_machine) == EM_MIPS) {
623  			reltype = R_MIPS_32;
624  			is_fake_mcount32 = MIPS32_is_fake_mcount;
625  		}
626  		if (w2(ehdr->e_machine) == EM_LOONGARCH) {
627  			reltype = R_LARCH_32;
628  			is_fake_mcount32 = LARCH32_is_fake_mcount;
629  		}
630  		if (do32(ehdr, fname, reltype) < 0)
631  			goto out;
632  		break;
633  	case ELFCLASS64: {
634  		Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
635  		if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
636  		||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
637  			fprintf(stderr,
638  				"unrecognized ET_REL file: %s\n", fname);
639  			goto out;
640  		}
641  		if (w2(ghdr->e_machine) == EM_S390) {
642  			reltype = R_390_64;
643  			mcount_adjust_64 = -14;
644  		}
645  		if (w2(ghdr->e_machine) == EM_MIPS) {
646  			reltype = R_MIPS_64;
647  			Elf64_r_sym = MIPS64_r_sym;
648  			Elf64_r_info = MIPS64_r_info;
649  			is_fake_mcount64 = MIPS64_is_fake_mcount;
650  		}
651  		if (w2(ghdr->e_machine) == EM_LOONGARCH) {
652  			reltype = R_LARCH_64;
653  			is_fake_mcount64 = LARCH64_is_fake_mcount;
654  		}
655  		if (do64(ghdr, fname, reltype) < 0)
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  
main(int argc,char * argv[])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 positive complaint */
673  	int c;
674  	int i;
675  
676  	while ((c = getopt(argc, argv, "w")) >= 0) {
677  		switch (c) {
678  		case 'w':
679  			warn_on_notrace_sect = 1;
680  			break;
681  		default:
682  			fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
683  			return 0;
684  		}
685  	}
686  
687  	if ((argc - optind) < 1) {
688  		fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
689  		return 0;
690  	}
691  
692  	/* Process each file in turn, allowing deep failure. */
693  	for (i = optind; i < argc; i++) {
694  		char *file = argv[i];
695  		int len;
696  
697  		/*
698  		 * The file kernel/trace/ftrace.o references the mcount
699  		 * function but does not call it. Since ftrace.o should
700  		 * not be traced anyway, we just skip it.
701  		 */
702  		len = strlen(file);
703  		if (len >= ftrace_size &&
704  		    strcmp(file + (len - ftrace_size), ftrace) == 0)
705  			continue;
706  
707  		if (do_file(file)) {
708  			fprintf(stderr, "%s: failed\n", file);
709  			++n_error;
710  		}
711  	}
712  	return !!n_error;
713  }
714