1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * recordmcount.h
4 *
5 * This code was taken out of recordmcount.c written by
6 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
7 *
8 * The original code had the same algorithms for both 32bit
9 * and 64bit ELF files, but the code was duplicated to support
10 * the difference in structures that were used. This
11 * file creates a macro of everything that is different between
12 * the 64 and 32 bit code, such that by including this header
13 * twice we can create both sets of functions by including this
14 * header once with RECORD_MCOUNT_64 undefined, and again with
15 * it defined.
16 *
17 * This conversion to macros was done by:
18 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
19 */
20 #undef append_func
21 #undef is_fake_mcount
22 #undef fn_is_fake_mcount
23 #undef MIPS_is_fake_mcount
24 #undef mcount_adjust
25 #undef sift_rel_mcount
26 #undef nop_mcount
27 #undef find_secsym_ndx
28 #undef __has_rel_mcount
29 #undef has_rel_mcount
30 #undef tot_relsize
31 #undef get_mcountsym
32 #undef find_symtab
33 #undef get_shnum
34 #undef set_shnum
35 #undef get_shstrndx
36 #undef get_symindex
37 #undef get_sym_str_and_relp
38 #undef do_func
39 #undef Elf_Addr
40 #undef Elf_Ehdr
41 #undef Elf_Shdr
42 #undef Elf_Rel
43 #undef Elf_Rela
44 #undef Elf_Sym
45 #undef ELF_R_SYM
46 #undef Elf_r_sym
47 #undef ELF_R_INFO
48 #undef Elf_r_info
49 #undef ELF_ST_BIND
50 #undef ELF_ST_TYPE
51 #undef fn_ELF_R_SYM
52 #undef fn_ELF_R_INFO
53 #undef uint_t
54 #undef _w
55 #undef _align
56 #undef _size
57
58 #ifdef RECORD_MCOUNT_64
59 # define append_func append64
60 # define sift_rel_mcount sift64_rel_mcount
61 # define nop_mcount nop_mcount_64
62 # define find_secsym_ndx find64_secsym_ndx
63 # define __has_rel_mcount __has64_rel_mcount
64 # define has_rel_mcount has64_rel_mcount
65 # define tot_relsize tot64_relsize
66 # define find_symtab find_symtab64
67 # define get_shnum get_shnum64
68 # define set_shnum set_shnum64
69 # define get_shstrndx get_shstrndx64
70 # define get_symindex get_symindex64
71 # define get_sym_str_and_relp get_sym_str_and_relp_64
72 # define do_func do64
73 # define get_mcountsym get_mcountsym_64
74 # define is_fake_mcount is_fake_mcount64
75 # define fn_is_fake_mcount fn_is_fake_mcount64
76 # define MIPS_is_fake_mcount MIPS64_is_fake_mcount
77 # define mcount_adjust mcount_adjust_64
78 # define Elf_Addr Elf64_Addr
79 # define Elf_Ehdr Elf64_Ehdr
80 # define Elf_Shdr Elf64_Shdr
81 # define Elf_Rel Elf64_Rel
82 # define Elf_Rela Elf64_Rela
83 # define Elf_Sym Elf64_Sym
84 # define ELF_R_SYM ELF64_R_SYM
85 # define Elf_r_sym Elf64_r_sym
86 # define ELF_R_INFO ELF64_R_INFO
87 # define Elf_r_info Elf64_r_info
88 # define ELF_ST_BIND ELF64_ST_BIND
89 # define ELF_ST_TYPE ELF64_ST_TYPE
90 # define fn_ELF_R_SYM fn_ELF64_R_SYM
91 # define fn_ELF_R_INFO fn_ELF64_R_INFO
92 # define uint_t uint64_t
93 # define _w w8
94 # define _align 7u
95 # define _size 8
96 #else
97 # define append_func append32
98 # define sift_rel_mcount sift32_rel_mcount
99 # define nop_mcount nop_mcount_32
100 # define find_secsym_ndx find32_secsym_ndx
101 # define __has_rel_mcount __has32_rel_mcount
102 # define has_rel_mcount has32_rel_mcount
103 # define tot_relsize tot32_relsize
104 # define find_symtab find_symtab32
105 # define get_shnum get_shnum32
106 # define set_shnum set_shnum32
107 # define get_shstrndx get_shstrndx32
108 # define get_symindex get_symindex32
109 # define get_sym_str_and_relp get_sym_str_and_relp_32
110 # define do_func do32
111 # define get_mcountsym get_mcountsym_32
112 # define is_fake_mcount is_fake_mcount32
113 # define fn_is_fake_mcount fn_is_fake_mcount32
114 # define MIPS_is_fake_mcount MIPS32_is_fake_mcount
115 # define mcount_adjust mcount_adjust_32
116 # define Elf_Addr Elf32_Addr
117 # define Elf_Ehdr Elf32_Ehdr
118 # define Elf_Shdr Elf32_Shdr
119 # define Elf_Rel Elf32_Rel
120 # define Elf_Rela Elf32_Rela
121 # define Elf_Sym Elf32_Sym
122 # define ELF_R_SYM ELF32_R_SYM
123 # define Elf_r_sym Elf32_r_sym
124 # define ELF_R_INFO ELF32_R_INFO
125 # define Elf_r_info Elf32_r_info
126 # define ELF_ST_BIND ELF32_ST_BIND
127 # define ELF_ST_TYPE ELF32_ST_TYPE
128 # define fn_ELF_R_SYM fn_ELF32_R_SYM
129 # define fn_ELF_R_INFO fn_ELF32_R_INFO
130 # define uint_t uint32_t
131 # define _w w
132 # define _align 3u
133 # define _size 4
134 #endif
135
136 /* Functions and pointers that do_file() may override for specific e_machine. */
137 static int fn_is_fake_mcount(Elf_Rel const *rp)
138 {
139 return 0;
140 }
141 static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
142
143 static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
144 {
145 return ELF_R_SYM(_w(rp->r_info));
146 }
147 static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
148
149 static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
150 {
151 rp->r_info = _w(ELF_R_INFO(sym, type));
152 }
153 static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
154
155 static int mcount_adjust = 0;
156
157 /*
158 * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
159 * _mcount symbol is needed for dynamic function tracer, with it, to disable
160 * tracing(ftrace_make_nop), the instruction in the position is replaced with
161 * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
162 * instruction back. So, here, we set the 2nd one as fake and filter it.
163 *
164 * c: 3c030000 lui v1,0x0 <--> b label
165 * c: R_MIPS_HI16 _mcount
166 * c: R_MIPS_NONE *ABS*
167 * c: R_MIPS_NONE *ABS*
168 * 10: 64630000 daddiu v1,v1,0
169 * 10: R_MIPS_LO16 _mcount
170 * 10: R_MIPS_NONE *ABS*
171 * 10: R_MIPS_NONE *ABS*
172 * 14: 03e0082d move at,ra
173 * 18: 0060f809 jalr v1
174 * label:
175 */
176 #define MIPS_FAKEMCOUNT_OFFSET 4
177
178 static int MIPS_is_fake_mcount(Elf_Rel const *rp)
179 {
180 static Elf_Addr old_r_offset = ~(Elf_Addr)0;
181 Elf_Addr current_r_offset = _w(rp->r_offset);
182 int is_fake;
183
184 is_fake = (old_r_offset != ~(Elf_Addr)0) &&
185 (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
186 old_r_offset = current_r_offset;
187
188 return is_fake;
189 }
190
191 static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab,
192 Elf32_Word const *symtab_shndx)
193 {
194 unsigned long offset;
195 unsigned short shndx = w2(sym->st_shndx);
196 int index;
197
198 if (shndx > SHN_UNDEF && shndx < SHN_LORESERVE)
199 return shndx;
200
201 if (shndx == SHN_XINDEX) {
202 offset = (unsigned long)sym - (unsigned long)symtab;
203 index = offset / sizeof(*sym);
204
205 return w(symtab_shndx[index]);
206 }
207
208 return 0;
209 }
210
211 static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
212 {
213 if (shdr0 && !ehdr->e_shnum)
214 return w(shdr0->sh_size);
215
216 return w2(ehdr->e_shnum);
217 }
218
219 static void set_shnum(Elf_Ehdr *ehdr, Elf_Shdr *shdr0, unsigned int new_shnum)
220 {
221 if (new_shnum >= SHN_LORESERVE) {
222 ehdr->e_shnum = 0;
223 shdr0->sh_size = w(new_shnum);
224 } else
225 ehdr->e_shnum = w2(new_shnum);
226 }
227
228 static int get_shstrndx(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
229 {
230 if (ehdr->e_shstrndx != SHN_XINDEX)
231 return w2(ehdr->e_shstrndx);
232
233 return w(shdr0->sh_link);
234 }
235
236 static void find_symtab(Elf_Ehdr *const ehdr, Elf_Shdr const *shdr0,
237 unsigned const nhdr, Elf32_Word **symtab,
238 Elf32_Word **symtab_shndx)
239 {
240 Elf_Shdr const *relhdr;
241 unsigned k;
242
243 *symtab = NULL;
244 *symtab_shndx = NULL;
245
246 for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
247 if (relhdr->sh_type == SHT_SYMTAB)
248 *symtab = (void *)ehdr + relhdr->sh_offset;
249 else if (relhdr->sh_type == SHT_SYMTAB_SHNDX)
250 *symtab_shndx = (void *)ehdr + relhdr->sh_offset;
251
252 if (*symtab && *symtab_shndx)
253 break;
254 }
255 }
256
257 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
258 static int append_func(Elf_Ehdr *const ehdr,
259 Elf_Shdr *const shstr,
260 uint_t const *const mloc0,
261 uint_t const *const mlocp,
262 Elf_Rel const *const mrel0,
263 Elf_Rel const *const mrelp,
264 unsigned int const rel_entsize,
265 unsigned int const symsec_sh_link)
266 {
267 /* Begin constructing output file */
268 Elf_Shdr mcsec;
269 char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
270 ? ".rela__mcount_loc"
271 : ".rel__mcount_loc";
272 uint_t const old_shoff = _w(ehdr->e_shoff);
273 uint_t const old_shstr_sh_size = _w(shstr->sh_size);
274 uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
275 Elf_Shdr *const shdr0 = (Elf_Shdr *)(old_shoff + (void *)ehdr);
276 unsigned int const old_shnum = get_shnum(ehdr, shdr0);
277 unsigned int const new_shnum = 2 + old_shnum; /* {.rel,}__mcount_loc */
278 uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
279 uint_t new_e_shoff;
280
281 shstr->sh_size = _w(t);
282 shstr->sh_offset = _w(sb.st_size);
283 t += sb.st_size;
284 t += (_align & -t); /* word-byte align */
285 new_e_shoff = t;
286
287 set_shnum(ehdr, shdr0, new_shnum);
288
289 /* body for new shstrtab */
290 if (ulseek(sb.st_size, SEEK_SET) < 0)
291 return -1;
292 if (uwrite(old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size) < 0)
293 return -1;
294 if (uwrite(mc_name, 1 + strlen(mc_name)) < 0)
295 return -1;
296
297 /* old(modified) Elf_Shdr table, word-byte aligned */
298 if (ulseek(t, SEEK_SET) < 0)
299 return -1;
300 t += sizeof(Elf_Shdr) * old_shnum;
301 if (uwrite(old_shoff + (void *)ehdr,
302 sizeof(Elf_Shdr) * old_shnum) < 0)
303 return -1;
304
305 /* new sections __mcount_loc and .rel__mcount_loc */
306 t += 2*sizeof(mcsec);
307 mcsec.sh_name = w((sizeof(Elf_Rela) == rel_entsize) + strlen(".rel")
308 + old_shstr_sh_size);
309 mcsec.sh_type = w(SHT_PROGBITS);
310 mcsec.sh_flags = _w(SHF_ALLOC);
311 mcsec.sh_addr = 0;
312 mcsec.sh_offset = _w(t);
313 mcsec.sh_size = _w((void *)mlocp - (void *)mloc0);
314 mcsec.sh_link = 0;
315 mcsec.sh_info = 0;
316 mcsec.sh_addralign = _w(_size);
317 mcsec.sh_entsize = _w(_size);
318 if (uwrite(&mcsec, sizeof(mcsec)) < 0)
319 return -1;
320
321 mcsec.sh_name = w(old_shstr_sh_size);
322 mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
323 ? w(SHT_RELA)
324 : w(SHT_REL);
325 mcsec.sh_flags = 0;
326 mcsec.sh_addr = 0;
327 mcsec.sh_offset = _w((void *)mlocp - (void *)mloc0 + t);
328 mcsec.sh_size = _w((void *)mrelp - (void *)mrel0);
329 mcsec.sh_link = w(symsec_sh_link);
330 mcsec.sh_info = w(old_shnum);
331 mcsec.sh_addralign = _w(_size);
332 mcsec.sh_entsize = _w(rel_entsize);
333
334 if (uwrite(&mcsec, sizeof(mcsec)) < 0)
335 return -1;
336
337 if (uwrite(mloc0, (void *)mlocp - (void *)mloc0) < 0)
338 return -1;
339 if (uwrite(mrel0, (void *)mrelp - (void *)mrel0) < 0)
340 return -1;
341
342 ehdr->e_shoff = _w(new_e_shoff);
343 if (ulseek(0, SEEK_SET) < 0)
344 return -1;
345 if (uwrite(ehdr, sizeof(*ehdr)) < 0)
346 return -1;
347 return 0;
348 }
349
350 static unsigned get_mcountsym(Elf_Sym const *const sym0,
351 Elf_Rel const *relp,
352 char const *const str0)
353 {
354 unsigned mcountsym = 0;
355
356 Elf_Sym const *const symp =
357 &sym0[Elf_r_sym(relp)];
358 char const *symname = &str0[w(symp->st_name)];
359 char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
360 char const *fentry = "__fentry__";
361
362 if (symname[0] == '.')
363 ++symname; /* ppc64 hack */
364 if (strcmp(mcount, symname) == 0 ||
365 (altmcount && strcmp(altmcount, symname) == 0) ||
366 (strcmp(fentry, symname) == 0))
367 mcountsym = Elf_r_sym(relp);
368
369 return mcountsym;
370 }
371
372 static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
373 Elf_Ehdr const *const ehdr,
374 Elf_Sym const **sym0,
375 char const **str0,
376 Elf_Rel const **relp)
377 {
378 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
379 + (void *)ehdr);
380 unsigned const symsec_sh_link = w(relhdr->sh_link);
381 Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
382 Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
383 Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
384 + (void *)ehdr);
385
386 *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
387 + (void *)ehdr);
388
389 *str0 = (char const *)(_w(strsec->sh_offset)
390 + (void *)ehdr);
391
392 *relp = rel0;
393 }
394
395 /*
396 * Look at the relocations in order to find the calls to mcount.
397 * Accumulate the section offsets that are found, and their relocation info,
398 * onto the end of the existing arrays.
399 */
400 static uint_t *sift_rel_mcount(uint_t *mlocp,
401 unsigned const offbase,
402 Elf_Rel **const mrelpp,
403 Elf_Shdr const *const relhdr,
404 Elf_Ehdr const *const ehdr,
405 unsigned const recsym,
406 uint_t const recval,
407 unsigned const reltype)
408 {
409 uint_t *const mloc0 = mlocp;
410 Elf_Rel *mrelp = *mrelpp;
411 Elf_Sym const *sym0;
412 char const *str0;
413 Elf_Rel const *relp;
414 unsigned rel_entsize = _w(relhdr->sh_entsize);
415 unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
416 unsigned mcountsym = 0;
417 unsigned t;
418
419 get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
420
421 for (t = nrel; t; --t) {
422 if (!mcountsym)
423 mcountsym = get_mcountsym(sym0, relp, str0);
424
425 if (mcountsym && mcountsym == Elf_r_sym(relp) &&
426 !is_fake_mcount(relp)) {
427 uint_t const addend =
428 _w(_w(relp->r_offset) - recval + mcount_adjust);
429 mrelp->r_offset = _w(offbase
430 + ((void *)mlocp - (void *)mloc0));
431 Elf_r_info(mrelp, recsym, reltype);
432 if (rel_entsize == sizeof(Elf_Rela)) {
433 ((Elf_Rela *)mrelp)->r_addend = addend;
434 *mlocp++ = 0;
435 } else
436 *mlocp++ = addend;
437
438 mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
439 }
440 relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
441 }
442 *mrelpp = mrelp;
443 return mlocp;
444 }
445
446 /*
447 * Read the relocation table again, but this time its called on sections
448 * that are not going to be traced. The mcount calls here will be converted
449 * into nops.
450 */
451 static int nop_mcount(Elf_Shdr const *const relhdr,
452 Elf_Ehdr const *const ehdr,
453 const char *const txtname)
454 {
455 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
456 + (void *)ehdr);
457 Elf_Sym const *sym0;
458 char const *str0;
459 Elf_Rel const *relp;
460 Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
461 unsigned rel_entsize = _w(relhdr->sh_entsize);
462 unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
463 unsigned mcountsym = 0;
464 unsigned t;
465 int once = 0;
466
467 get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
468
469 for (t = nrel; t; --t) {
470 int ret = -1;
471
472 if (!mcountsym)
473 mcountsym = get_mcountsym(sym0, relp, str0);
474
475 if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
476 if (make_nop)
477 ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
478 if (warn_on_notrace_sect && !once) {
479 printf("Section %s has mcount callers being ignored\n",
480 txtname);
481 once = 1;
482 /* just warn? */
483 if (!make_nop)
484 return 0;
485 }
486 }
487
488 /*
489 * If we successfully removed the mcount, mark the relocation
490 * as a nop (don't do anything with it).
491 */
492 if (!ret) {
493 Elf_Rel rel;
494 rel = *(Elf_Rel *)relp;
495 Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
496 if (ulseek((void *)relp - (void *)ehdr, SEEK_SET) < 0)
497 return -1;
498 if (uwrite(&rel, sizeof(rel)) < 0)
499 return -1;
500 }
501 relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
502 }
503 return 0;
504 }
505
506 /*
507 * Find a symbol in the given section, to be used as the base for relocating
508 * the table of offsets of calls to mcount. A local or global symbol suffices,
509 * but avoid a Weak symbol because it may be overridden; the change in value
510 * would invalidate the relocations of the offsets of the calls to mcount.
511 * Often the found symbol will be the unnamed local symbol generated by
512 * GNU 'as' for the start of each section. For example:
513 * Num: Value Size Type Bind Vis Ndx Name
514 * 2: 00000000 0 SECTION LOCAL DEFAULT 1
515 */
516 static int find_secsym_ndx(unsigned const txtndx,
517 char const *const txtname,
518 uint_t *const recvalp,
519 unsigned int *sym_index,
520 Elf_Shdr const *const symhdr,
521 Elf32_Word const *symtab,
522 Elf32_Word const *symtab_shndx,
523 Elf_Ehdr const *const ehdr)
524 {
525 Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
526 + (void *)ehdr);
527 unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
528 Elf_Sym const *symp;
529 unsigned t;
530
531 for (symp = sym0, t = nsym; t; --t, ++symp) {
532 unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
533
534 if (txtndx == get_symindex(symp, symtab, symtab_shndx)
535 /* avoid STB_WEAK */
536 && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
537 /* function symbols on ARM have quirks, avoid them */
538 if (w2(ehdr->e_machine) == EM_ARM
539 && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
540 continue;
541
542 *recvalp = _w(symp->st_value);
543 *sym_index = symp - sym0;
544 return 0;
545 }
546 }
547 fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
548 txtndx, txtname);
549 return -1;
550 }
551
552 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
553 static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
554 Elf_Shdr const *const shdr0,
555 char const *const shstrtab,
556 char const *const fname)
557 {
558 /* .sh_info depends on .sh_type == SHT_REL[,A] */
559 Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
560 char const *const txtname = &shstrtab[w(txthdr->sh_name)];
561
562 if (strcmp("__mcount_loc", txtname) == 0) {
563 fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
564 fname);
565 return already_has_rel_mcount;
566 }
567 if (w(txthdr->sh_type) != SHT_PROGBITS ||
568 !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
569 return NULL;
570 return txtname;
571 }
572
573 static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
574 Elf_Shdr const *const shdr0,
575 char const *const shstrtab,
576 char const *const fname)
577 {
578 if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
579 return NULL;
580 return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
581 }
582
583
584 static unsigned tot_relsize(Elf_Shdr const *const shdr0,
585 unsigned nhdr,
586 const char *const shstrtab,
587 const char *const fname)
588 {
589 unsigned totrelsz = 0;
590 Elf_Shdr const *shdrp = shdr0;
591 char const *txtname;
592
593 for (; nhdr; --nhdr, ++shdrp) {
594 txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
595 if (txtname == already_has_rel_mcount) {
596 totrelsz = 0;
597 break;
598 }
599 if (txtname && is_mcounted_section_name(txtname))
600 totrelsz += _w(shdrp->sh_size);
601 }
602 return totrelsz;
603 }
604
605 /* Overall supervision for Elf32 ET_REL file. */
606 static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
607 unsigned const reltype)
608 {
609 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
610 + (void *)ehdr);
611 unsigned const nhdr = get_shnum(ehdr, shdr0);
612 Elf_Shdr *const shstr = &shdr0[get_shstrndx(ehdr, shdr0)];
613 char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
614 + (void *)ehdr);
615
616 Elf_Shdr const *relhdr;
617 unsigned k;
618
619 Elf32_Word *symtab;
620 Elf32_Word *symtab_shndx;
621
622 /* Upper bound on space: assume all relevant relocs are for mcount. */
623 unsigned totrelsz;
624
625 Elf_Rel * mrel0;
626 Elf_Rel * mrelp;
627
628 uint_t * mloc0;
629 uint_t * mlocp;
630
631 unsigned rel_entsize = 0;
632 unsigned symsec_sh_link = 0;
633
634 int result = 0;
635
636 totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
637 if (totrelsz == 0)
638 return 0;
639 mrel0 = umalloc(totrelsz);
640 mrelp = mrel0;
641 if (!mrel0)
642 return -1;
643
644 /* 2*sizeof(address) <= sizeof(Elf_Rel) */
645 mloc0 = umalloc(totrelsz>>1);
646 mlocp = mloc0;
647 if (!mloc0) {
648 free(mrel0);
649 return -1;
650 }
651
652 find_symtab(ehdr, shdr0, nhdr, &symtab, &symtab_shndx);
653
654 for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
655 char const *const txtname = has_rel_mcount(relhdr, shdr0,
656 shstrtab, fname);
657 if (txtname == already_has_rel_mcount) {
658 result = 0;
659 file_updated = 0;
660 goto out; /* Nothing to be done; don't append! */
661 }
662 if (txtname && is_mcounted_section_name(txtname)) {
663 unsigned int recsym;
664 uint_t recval = 0;
665
666 symsec_sh_link = w(relhdr->sh_link);
667 result = find_secsym_ndx(w(relhdr->sh_info), txtname,
668 &recval, &recsym,
669 &shdr0[symsec_sh_link],
670 symtab, symtab_shndx,
671 ehdr);
672 if (result)
673 goto out;
674
675 rel_entsize = _w(relhdr->sh_entsize);
676 mlocp = sift_rel_mcount(mlocp,
677 (void *)mlocp - (void *)mloc0, &mrelp,
678 relhdr, ehdr, recsym, recval, reltype);
679 } else if (txtname && (warn_on_notrace_sect || make_nop)) {
680 /*
681 * This section is ignored by ftrace, but still
682 * has mcount calls. Convert them to nops now.
683 */
684 if (nop_mcount(relhdr, ehdr, txtname) < 0) {
685 result = -1;
686 goto out;
687 }
688 }
689 }
690 if (!result && mloc0 != mlocp)
691 result = append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
692 rel_entsize, symsec_sh_link);
693 out:
694 free(mrel0);
695 free(mloc0);
696 return result;
697 }
698
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.