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authorJohn Reiser <jreiser@bitwagon.com>2010-10-13 15:12:54 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-10-14 16:44:34 -0400
commit81d3858d3131a589cade0d8b57f95cc1fc699b89 (patch)
treea79260842b6de29a065e52f891e1527336e6e999
parent3cba11d32bb4b24c3ba257043595772df4b9c7b5 (diff)
ftrace: Add C version of recordmcount compile time code
Currently, the mcount callers are found with a perl script that does an objdump on every file in the kernel. This is a C version of that same code which should increase the performance time of compiling the kernel with dynamic ftrace enabled. Signed-off-by: John Reiser <jreiser@bitwagon.com> [ Updated the code to include .text.unlikely section as well as changing the format to follow Linux coding style. ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat
-rw-r--r--scripts/recordmcount.c885
1 files changed, 885 insertions, 0 deletions
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
new file mode 100644
index 000000000000..34f32be17090
--- /dev/null
+++ b/scripts/recordmcount.c
@@ -0,0 +1,885 @@
1/*
2 * recordmcount.c: construct a table of the locations of calls to 'mcount'
3 * so that ftrace can find them quickly.
4 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
5 * Licensed under the GNU General Public License, version 2 (GPLv2).
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 <elf.h>
28#include <fcntl.h>
29#include <setjmp.h>
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33#include <unistd.h>
34
35static int fd_map; /* File descriptor for file being modified. */
36static int mmap_failed; /* Boolean flag. */
37static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
38static char gpfx; /* prefix for global symbol name (sometimes '_') */
39static struct stat sb; /* Remember .st_size, etc. */
40static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
41
42/* setjmp() return values */
43enum {
44 SJ_SETJMP = 0, /* hardwired first return */
45 SJ_FAIL,
46 SJ_SUCCEED
47};
48
49/* Per-file resource cleanup when multiple files. */
50static void
51cleanup(void)
52{
53 if (!mmap_failed)
54 munmap(ehdr_curr, sb.st_size);
55 else
56 free(ehdr_curr);
57 close(fd_map);
58}
59
60static void __attribute__((noreturn))
61fail_file(void)
62{
63 cleanup();
64 longjmp(jmpenv, SJ_FAIL);
65}
66
67static void __attribute__((noreturn))
68succeed_file(void)
69{
70 cleanup();
71 longjmp(jmpenv, SJ_SUCCEED);
72}
73
74/* ulseek, uread, ...: Check return value for errors. */
75
76static off_t
77ulseek(int const fd, off_t const offset, int const whence)
78{
79 off_t const w = lseek(fd, offset, whence);
80 if ((off_t)-1 == w) {
81 perror("lseek");
82 fail_file();
83 }
84 return w;
85}
86
87static size_t
88uread(int const fd, void *const buf, size_t const count)
89{
90 size_t const n = read(fd, buf, count);
91 if (n != count) {
92 perror("read");
93 fail_file();
94 }
95 return n;
96}
97
98static size_t
99uwrite(int const fd, void const *const buf, size_t const count)
100{
101 size_t const n = write(fd, buf, count);
102 if (n != count) {
103 perror("write");
104 fail_file();
105 }
106 return n;
107}
108
109static void *
110umalloc(size_t size)
111{
112 void *const addr = malloc(size);
113 if (0 == addr) {
114 fprintf(stderr, "malloc failed: %zu bytes\n", size);
115 fail_file();
116 }
117 return addr;
118}
119
120/*
121 * Get the whole file as a programming convenience in order to avoid
122 * malloc+lseek+read+free of many pieces. If successful, then mmap
123 * avoids copying unused pieces; else just read the whole file.
124 * Open for both read and write; new info will be appended to the file.
125 * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
126 * do not propagate to the file until an explicit overwrite at the last.
127 * This preserves most aspects of consistency (all except .st_size)
128 * for simultaneous readers of the file while we are appending to it.
129 * However, multiple writers still are bad. We choose not to use
130 * locking because it is expensive and the use case of kernel build
131 * makes multiple writers unlikely.
132 */
133static void *mmap_file(char const *fname)
134{
135 void *addr;
136
137 fd_map = open(fname, O_RDWR);
138 if (0 > fd_map || 0 > fstat(fd_map, &sb)) {
139 perror(fname);
140 fail_file();
141 }
142 if (!S_ISREG(sb.st_mode)) {
143 fprintf(stderr, "not a regular file: %s\n", fname);
144 fail_file();
145 }
146 addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
147 fd_map, 0);
148 mmap_failed = 0;
149 if (MAP_FAILED == addr) {
150 mmap_failed = 1;
151 addr = umalloc(sb.st_size);
152 uread(fd_map, addr, sb.st_size);
153 }
154 return addr;
155}
156
157/* w8rev, w8nat, ...: Handle endianness. */
158
159static uint64_t w8rev(uint64_t const x)
160{
161 return ((0xff & (x >> (0 * 8))) << (7 * 8))
162 | ((0xff & (x >> (1 * 8))) << (6 * 8))
163 | ((0xff & (x >> (2 * 8))) << (5 * 8))
164 | ((0xff & (x >> (3 * 8))) << (4 * 8))
165 | ((0xff & (x >> (4 * 8))) << (3 * 8))
166 | ((0xff & (x >> (5 * 8))) << (2 * 8))
167 | ((0xff & (x >> (6 * 8))) << (1 * 8))
168 | ((0xff & (x >> (7 * 8))) << (0 * 8));
169}
170
171static uint32_t w4rev(uint32_t const x)
172{
173 return ((0xff & (x >> (0 * 8))) << (3 * 8))
174 | ((0xff & (x >> (1 * 8))) << (2 * 8))
175 | ((0xff & (x >> (2 * 8))) << (1 * 8))
176 | ((0xff & (x >> (3 * 8))) << (0 * 8));
177}
178
179static uint32_t w2rev(uint16_t const x)
180{
181 return ((0xff & (x >> (0 * 8))) << (1 * 8))
182 | ((0xff & (x >> (1 * 8))) << (0 * 8));
183}
184
185static uint64_t w8nat(uint64_t const x)
186{
187 return x;
188}
189
190static uint32_t w4nat(uint32_t const x)
191{
192 return x;
193}
194
195static uint32_t w2nat(uint16_t const x)
196{
197 return x;
198}
199
200static uint64_t (*w8)(uint64_t);
201static uint32_t (*w)(uint32_t);
202static uint32_t (*w2)(uint16_t);
203
204/* Names of the sections that could contain calls to mcount. */
205static int
206is_mcounted_section_name(char const *const txtname)
207{
208 return 0 == strcmp(".text", txtname) ||
209 0 == strcmp(".sched.text", txtname) ||
210 0 == strcmp(".spinlock.text", txtname) ||
211 0 == strcmp(".irqentry.text", txtname) ||
212 0 == strcmp(".text.unlikely", txtname);
213}
214
215/* Append the new shstrtab, Elf32_Shdr[], __mcount_loc and its relocations. */
216static void append32(Elf32_Ehdr *const ehdr,
217 Elf32_Shdr *const shstr,
218 uint32_t const *const mloc0,
219 uint32_t const *const mlocp,
220 Elf32_Rel const *const mrel0,
221 Elf32_Rel const *const mrelp,
222 unsigned int const rel_entsize,
223 unsigned int const symsec_sh_link)
224{
225 /* Begin constructing output file */
226 Elf32_Shdr mcsec;
227 char const *mc_name = (sizeof(Elf32_Rela) == rel_entsize)
228 ? ".rela__mcount_loc"
229 : ".rel__mcount_loc";
230 unsigned const old_shnum = w2(ehdr->e_shnum);
231 uint32_t const old_shoff = w(ehdr->e_shoff);
232 uint32_t const old_shstr_sh_size = w(shstr->sh_size);
233 uint32_t const old_shstr_sh_offset = w(shstr->sh_offset);
234 uint32_t t = 1 + strlen(mc_name) + w(shstr->sh_size);
235 uint32_t new_e_shoff;
236
237 shstr->sh_size = w(t);
238 shstr->sh_offset = w(sb.st_size);
239 t += sb.st_size;
240 t += (3u & -t); /* 4-byte align */
241 new_e_shoff = t;
242
243 /* body for new shstrtab */
244 ulseek(fd_map, sb.st_size, SEEK_SET);
245 uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
246 uwrite(fd_map, mc_name, 1 + strlen(mc_name));
247
248 /* old(modified) Elf32_Shdr table, 4-byte aligned */
249 ulseek(fd_map, t, SEEK_SET);
250 t += sizeof(Elf32_Shdr) * old_shnum;
251 uwrite(fd_map, old_shoff + (void *)ehdr,
252 sizeof(Elf32_Shdr) * old_shnum);
253
254 /* new sections __mcount_loc and .rel__mcount_loc */
255 t += 2*sizeof(mcsec);
256 mcsec.sh_name = w((sizeof(Elf32_Rela) == rel_entsize) + strlen(".rel")
257 + old_shstr_sh_size);
258 mcsec.sh_type = w(SHT_PROGBITS);
259 mcsec.sh_flags = w(SHF_ALLOC);
260 mcsec.sh_addr = 0;
261 mcsec.sh_offset = w(t);
262 mcsec.sh_size = w((void *)mlocp - (void *)mloc0);
263 mcsec.sh_link = 0;
264 mcsec.sh_info = 0;
265 mcsec.sh_addralign = w(4);
266 mcsec.sh_entsize = w(4);
267 uwrite(fd_map, &mcsec, sizeof(mcsec));
268
269 mcsec.sh_name = w(old_shstr_sh_size);
270 mcsec.sh_type = (sizeof(Elf32_Rela) == rel_entsize)
271 ? w(SHT_RELA)
272 : w(SHT_REL);
273 mcsec.sh_flags = 0;
274 mcsec.sh_addr = 0;
275 mcsec.sh_offset = w((void *)mlocp - (void *)mloc0 + t);
276 mcsec.sh_size = w((void *)mrelp - (void *)mrel0);
277 mcsec.sh_link = w(symsec_sh_link);
278 mcsec.sh_info = w(old_shnum);
279 mcsec.sh_addralign = w(4);
280 mcsec.sh_entsize = w(rel_entsize);
281 uwrite(fd_map, &mcsec, sizeof(mcsec));
282
283 uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);
284 uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);
285
286 ehdr->e_shoff = w(new_e_shoff);
287 ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum)); /* {.rel,}__mcount_loc */
288 ulseek(fd_map, 0, SEEK_SET);
289 uwrite(fd_map, ehdr, sizeof(*ehdr));
290}
291
292/*
293 * append64 and append32 (and other analogous pairs) could be templated
294 * using C++, but the complexity is high. (For an example, look at p_elf.h
295 * in the source for UPX, http://upx.sourceforge.net) So: remember to make
296 * the corresponding change in the routine for the other size.
297 */
298static void append64(Elf64_Ehdr *const ehdr,
299 Elf64_Shdr *const shstr,
300 uint64_t const *const mloc0,
301 uint64_t const *const mlocp,
302 Elf64_Rel const *const mrel0,
303 Elf64_Rel const *const mrelp,
304 unsigned int const rel_entsize,
305 unsigned int const symsec_sh_link)
306{
307 /* Begin constructing output file */
308 Elf64_Shdr mcsec;
309 char const *mc_name = (sizeof(Elf64_Rela) == rel_entsize)
310 ? ".rela__mcount_loc"
311 : ".rel__mcount_loc";
312 unsigned const old_shnum = w2(ehdr->e_shnum);
313 uint64_t const old_shoff = w8(ehdr->e_shoff);
314 uint64_t const old_shstr_sh_size = w8(shstr->sh_size);
315 uint64_t const old_shstr_sh_offset = w8(shstr->sh_offset);
316 uint64_t t = 1 + strlen(mc_name) + w8(shstr->sh_size);
317 uint64_t new_e_shoff;
318
319 shstr->sh_size = w8(t);
320 shstr->sh_offset = w8(sb.st_size);
321 t += sb.st_size;
322 t += (7u & -t); /* 8-byte align */
323 new_e_shoff = t;
324
325 /* body for new shstrtab */
326 ulseek(fd_map, sb.st_size, SEEK_SET);
327 uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
328 uwrite(fd_map, mc_name, 1 + strlen(mc_name));
329
330 /* old(modified) Elf64_Shdr table, 8-byte aligned */
331 ulseek(fd_map, t, SEEK_SET);
332 t += sizeof(Elf64_Shdr) * old_shnum;
333 uwrite(fd_map, old_shoff + (void *)ehdr,
334 sizeof(Elf64_Shdr) * old_shnum);
335
336 /* new sections __mcount_loc and .rel__mcount_loc */
337 t += 2*sizeof(mcsec);
338 mcsec.sh_name = w((sizeof(Elf64_Rela) == rel_entsize) + strlen(".rel")
339 + old_shstr_sh_size);
340 mcsec.sh_type = w(SHT_PROGBITS);
341 mcsec.sh_flags = w8(SHF_ALLOC);
342 mcsec.sh_addr = 0;
343 mcsec.sh_offset = w8(t);
344 mcsec.sh_size = w8((void *)mlocp - (void *)mloc0);
345 mcsec.sh_link = 0;
346 mcsec.sh_info = 0;
347 mcsec.sh_addralign = w8(8);
348 mcsec.sh_entsize = w8(8);
349 uwrite(fd_map, &mcsec, sizeof(mcsec));
350
351 mcsec.sh_name = w(old_shstr_sh_size);
352 mcsec.sh_type = (sizeof(Elf64_Rela) == rel_entsize)
353 ? w(SHT_RELA)
354 : w(SHT_REL);
355 mcsec.sh_flags = 0;
356 mcsec.sh_addr = 0;
357 mcsec.sh_offset = w8((void *)mlocp - (void *)mloc0 + t);
358 mcsec.sh_size = w8((void *)mrelp - (void *)mrel0);
359 mcsec.sh_link = w(symsec_sh_link);
360 mcsec.sh_info = w(old_shnum);
361 mcsec.sh_addralign = w8(8);
362 mcsec.sh_entsize = w8(rel_entsize);
363 uwrite(fd_map, &mcsec, sizeof(mcsec));
364
365 uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);
366 uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);
367
368 ehdr->e_shoff = w8(new_e_shoff);
369 ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum)); /* {.rel,}__mcount_loc */
370 ulseek(fd_map, 0, SEEK_SET);
371 uwrite(fd_map, ehdr, sizeof(*ehdr));
372}
373
374/*
375 * Look at the relocations in order to find the calls to mcount.
376 * Accumulate the section offsets that are found, and their relocation info,
377 * onto the end of the existing arrays.
378 */
379static uint32_t *sift32_rel_mcount(uint32_t *mlocp,
380 unsigned const offbase,
381 Elf32_Rel **const mrelpp,
382 Elf32_Shdr const *const relhdr,
383 Elf32_Ehdr const *const ehdr,
384 unsigned const recsym,
385 uint32_t const recval,
386 unsigned const reltype)
387{
388 uint32_t *const mloc0 = mlocp;
389 Elf32_Rel *mrelp = *mrelpp;
390 Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)
391 + (void *)ehdr);
392 unsigned const symsec_sh_link = w(relhdr->sh_link);
393 Elf32_Shdr const *const symsec = &shdr0[symsec_sh_link];
394 Elf32_Sym const *const sym0 = (Elf32_Sym const *)(w(symsec->sh_offset)
395 + (void *)ehdr);
396
397 Elf32_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
398 char const *const str0 = (char const *)(w(strsec->sh_offset)
399 + (void *)ehdr);
400
401 Elf32_Rel const *const rel0 = (Elf32_Rel const *)(w(relhdr->sh_offset)
402 + (void *)ehdr);
403 unsigned rel_entsize = w(relhdr->sh_entsize);
404 unsigned const nrel = w(relhdr->sh_size) / rel_entsize;
405 Elf32_Rel const *relp = rel0;
406
407 unsigned mcountsym = 0;
408 unsigned t;
409
410 for (t = nrel; t; --t) {
411 if (!mcountsym) {
412 Elf32_Sym const *const symp =
413 &sym0[ELF32_R_SYM(w(relp->r_info))];
414
415 if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
416 &str0[w(symp->st_name)]))
417 mcountsym = ELF32_R_SYM(w(relp->r_info));
418 }
419 if (mcountsym == ELF32_R_SYM(w(relp->r_info))) {
420 uint32_t const addend = w(w(relp->r_offset) - recval);
421 mrelp->r_offset = w(offbase
422 + ((void *)mlocp - (void *)mloc0));
423 mrelp->r_info = w(ELF32_R_INFO(recsym, reltype));
424 if (sizeof(Elf32_Rela) == rel_entsize) {
425 ((Elf32_Rela *)mrelp)->r_addend = addend;
426 *mlocp++ = 0;
427 } else
428 *mlocp++ = addend;
429
430 mrelp = (Elf32_Rel *)(rel_entsize + (void *)mrelp);
431 }
432 relp = (Elf32_Rel const *)(rel_entsize + (void *)relp);
433 }
434 *mrelpp = mrelp;
435 return mlocp;
436}
437
438static uint64_t *sift64_rel_mcount(uint64_t *mlocp,
439 unsigned const offbase,
440 Elf64_Rel **const mrelpp,
441 Elf64_Shdr const *const relhdr,
442 Elf64_Ehdr const *const ehdr,
443 unsigned const recsym,
444 uint64_t const recval,
445 unsigned const reltype)
446{
447 uint64_t *const mloc0 = mlocp;
448 Elf64_Rel *mrelp = *mrelpp;
449 Elf64_Shdr *const shdr0 = (Elf64_Shdr *)(w8(ehdr->e_shoff)
450 + (void *)ehdr);
451 unsigned const symsec_sh_link = w(relhdr->sh_link);
452 Elf64_Shdr const *const symsec = &shdr0[symsec_sh_link];
453 Elf64_Sym const *const sym0 = (Elf64_Sym const *)(w8(symsec->sh_offset)
454 + (void *)ehdr);
455
456 Elf64_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
457 char const *const str0 = (char const *)(w8(strsec->sh_offset)
458 + (void *)ehdr);
459
460 Elf64_Rel const *const rel0 = (Elf64_Rel const *)(w8(relhdr->sh_offset)
461 + (void *)ehdr);
462 unsigned rel_entsize = w8(relhdr->sh_entsize);
463 unsigned const nrel = w8(relhdr->sh_size) / rel_entsize;
464 Elf64_Rel const *relp = rel0;
465
466 unsigned mcountsym = 0;
467 unsigned t;
468
469 for (t = nrel; 0 != t; --t) {
470 if (!mcountsym) {
471 Elf64_Sym const *const symp =
472 &sym0[ELF64_R_SYM(w8(relp->r_info))];
473 char const *symname = &str0[w(symp->st_name)];
474
475 if ('.' == symname[0])
476 ++symname; /* ppc64 hack */
477 if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
478 symname))
479 mcountsym = ELF64_R_SYM(w8(relp->r_info));
480 }
481
482 if (mcountsym == ELF64_R_SYM(w8(relp->r_info))) {
483 uint64_t const addend = w8(w8(relp->r_offset) - recval);
484
485 mrelp->r_offset = w8(offbase
486 + ((void *)mlocp - (void *)mloc0));
487 mrelp->r_info = w8(ELF64_R_INFO(recsym, reltype));
488 if (sizeof(Elf64_Rela) == rel_entsize) {
489 ((Elf64_Rela *)mrelp)->r_addend = addend;
490 *mlocp++ = 0;
491 } else
492 *mlocp++ = addend;
493
494 mrelp = (Elf64_Rel *)(rel_entsize + (void *)mrelp);
495 }
496 relp = (Elf64_Rel const *)(rel_entsize + (void *)relp);
497 }
498 *mrelpp = mrelp;
499
500 return mlocp;
501}
502
503/*
504 * Find a symbol in the given section, to be used as the base for relocating
505 * the table of offsets of calls to mcount. A local or global symbol suffices,
506 * but avoid a Weak symbol because it may be overridden; the change in value
507 * would invalidate the relocations of the offsets of the calls to mcount.
508 * Often the found symbol will be the unnamed local symbol generated by
509 * GNU 'as' for the start of each section. For example:
510 * Num: Value Size Type Bind Vis Ndx Name
511 * 2: 00000000 0 SECTION LOCAL DEFAULT 1
512 */
513static unsigned find32_secsym_ndx(unsigned const txtndx,
514 char const *const txtname,
515 uint32_t *const recvalp,
516 Elf32_Shdr const *const symhdr,
517 Elf32_Ehdr const *const ehdr)
518{
519 Elf32_Sym const *const sym0 = (Elf32_Sym const *)(w(symhdr->sh_offset)
520 + (void *)ehdr);
521 unsigned const nsym = w(symhdr->sh_size) / w(symhdr->sh_entsize);
522 Elf32_Sym const *symp;
523 unsigned t;
524
525 for (symp = sym0, t = nsym; t; --t, ++symp) {
526 unsigned int const st_bind = ELF32_ST_BIND(symp->st_info);
527
528 if (txtndx == w2(symp->st_shndx)
529 /* avoid STB_WEAK */
530 && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
531 *recvalp = w(symp->st_value);
532 return symp - sym0;
533 }
534 }
535 fprintf(stderr, "Cannot find symbol for section %d: %s.\n",
536 txtndx, txtname);
537 fail_file();
538}
539
540static unsigned find64_secsym_ndx(unsigned const txtndx,
541 char const *const txtname,
542 uint64_t *const recvalp,
543 Elf64_Shdr const *const symhdr,
544 Elf64_Ehdr const *const ehdr)
545{
546 Elf64_Sym const *const sym0 = (Elf64_Sym const *)(w8(symhdr->sh_offset)
547 + (void *)ehdr);
548 unsigned const nsym = w8(symhdr->sh_size) / w8(symhdr->sh_entsize);
549 Elf64_Sym const *symp;
550 unsigned t;
551
552 for (symp = sym0, t = nsym; t; --t, ++symp) {
553 unsigned int const st_bind = ELF64_ST_BIND(symp->st_info);
554
555 if (txtndx == w2(symp->st_shndx)
556 /* avoid STB_WEAK */
557 && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
558 *recvalp = w8(symp->st_value);
559 return symp - sym0;
560 }
561 }
562 fprintf(stderr, "Cannot find symbol for section %d: %s.\n",
563 txtndx, txtname);
564 fail_file();
565}
566
567/*
568 * Evade ISO C restriction: no declaration after statement in
569 * has32_rel_mcount.
570 */
571static char const *
572__has32_rel_mcount(Elf32_Shdr const *const relhdr, /* is SHT_REL or SHT_RELA */
573 Elf32_Shdr const *const shdr0,
574 char const *const shstrtab,
575 char const *const fname)
576{
577 /* .sh_info depends on .sh_type == SHT_REL[,A] */
578 Elf32_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
579 char const *const txtname = &shstrtab[w(txthdr->sh_name)];
580
581 if (0 == strcmp("__mcount_loc", txtname)) {
582 fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
583 fname);
584 succeed_file();
585 }
586 if (SHT_PROGBITS != w(txthdr->sh_type) ||
587 !is_mcounted_section_name(txtname))
588 return NULL;
589 return txtname;
590}
591
592static char const *has32_rel_mcount(Elf32_Shdr const *const relhdr,
593 Elf32_Shdr const *const shdr0,
594 char const *const shstrtab,
595 char const *const fname)
596{
597 if (SHT_REL != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))
598 return NULL;
599 return __has32_rel_mcount(relhdr, shdr0, shstrtab, fname);
600}
601
602static char const *__has64_rel_mcount(Elf64_Shdr const *const relhdr,
603 Elf64_Shdr const *const shdr0,
604 char const *const shstrtab,
605 char const *const fname)
606{
607 /* .sh_info depends on .sh_type == SHT_REL[,A] */
608 Elf64_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
609 char const *const txtname = &shstrtab[w(txthdr->sh_name)];
610
611 if (0 == strcmp("__mcount_loc", txtname)) {
612 fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
613 fname);
614 succeed_file();
615 }
616 if (SHT_PROGBITS != w(txthdr->sh_type) ||
617 !is_mcounted_section_name(txtname))
618 return NULL;
619 return txtname;
620}
621
622static char const *has64_rel_mcount(Elf64_Shdr const *const relhdr,
623 Elf64_Shdr const *const shdr0,
624 char const *const shstrtab,
625 char const *const fname)
626{
627 if (SHT_REL != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))
628 return NULL;
629 return __has64_rel_mcount(relhdr, shdr0, shstrtab, fname);
630}
631
632static unsigned tot32_relsize(Elf32_Shdr const *const shdr0,
633 unsigned nhdr,
634 const char *const shstrtab,
635 const char *const fname)
636{
637 unsigned totrelsz = 0;
638 Elf32_Shdr const *shdrp = shdr0;
639 for (; 0 != nhdr; --nhdr, ++shdrp) {
640 if (has32_rel_mcount(shdrp, shdr0, shstrtab, fname))
641 totrelsz += w(shdrp->sh_size);
642 }
643 return totrelsz;
644}
645
646static unsigned tot64_relsize(Elf64_Shdr const *const shdr0,
647 unsigned nhdr,
648 const char *const shstrtab,
649 const char *const fname)
650{
651 unsigned totrelsz = 0;
652 Elf64_Shdr const *shdrp = shdr0;
653
654 for (; nhdr; --nhdr, ++shdrp) {
655 if (has64_rel_mcount(shdrp, shdr0, shstrtab, fname))
656 totrelsz += w8(shdrp->sh_size);
657 }
658 return totrelsz;
659}
660
661/* Overall supervision for Elf32 ET_REL file. */
662static void
663do32(Elf32_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
664{
665 Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)
666 + (void *)ehdr);
667 unsigned const nhdr = w2(ehdr->e_shnum);
668 Elf32_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
669 char const *const shstrtab = (char const *)(w(shstr->sh_offset)
670 + (void *)ehdr);
671
672 Elf32_Shdr const *relhdr;
673 unsigned k;
674
675 /* Upper bound on space: assume all relevant relocs are for mcount. */
676 unsigned const totrelsz = tot32_relsize(shdr0, nhdr, shstrtab, fname);
677 Elf32_Rel *const mrel0 = umalloc(totrelsz);
678 Elf32_Rel * mrelp = mrel0;
679
680 /* 2*sizeof(address) <= sizeof(Elf32_Rel) */
681 uint32_t *const mloc0 = umalloc(totrelsz>>1);
682 uint32_t * mlocp = mloc0;
683
684 unsigned rel_entsize = 0;
685 unsigned symsec_sh_link = 0;
686
687 for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
688 char const *const txtname = has32_rel_mcount(relhdr, shdr0,
689 shstrtab, fname);
690 if (txtname) {
691 uint32_t recval = 0;
692 unsigned const recsym = find32_secsym_ndx(
693 w(relhdr->sh_info), txtname, &recval,
694 &shdr0[symsec_sh_link = w(relhdr->sh_link)],
695 ehdr);
696
697 rel_entsize = w(relhdr->sh_entsize);
698 mlocp = sift32_rel_mcount(mlocp,
699 (void *)mlocp - (void *)mloc0, &mrelp,
700 relhdr, ehdr, recsym, recval, reltype);
701 }
702 }
703 if (mloc0 != mlocp) {
704 append32(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
705 rel_entsize, symsec_sh_link);
706 }
707 free(mrel0);
708 free(mloc0);
709}
710
711static void
712do64(Elf64_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
713{
714 Elf64_Shdr *const shdr0 = (Elf64_Shdr *)(w8(ehdr->e_shoff)
715 + (void *)ehdr);
716 unsigned const nhdr = w2(ehdr->e_shnum);
717 Elf64_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
718 char const *const shstrtab = (char const *)(w8(shstr->sh_offset)
719 + (void *)ehdr);
720
721 Elf64_Shdr const *relhdr;
722 unsigned k;
723
724 /* Upper bound on space: assume all relevant relocs are for mcount. */
725 unsigned const totrelsz = tot64_relsize(shdr0, nhdr, shstrtab, fname);
726 Elf64_Rel *const mrel0 = umalloc(totrelsz);
727 Elf64_Rel * mrelp = mrel0;
728
729 /* 2*sizeof(address) <= sizeof(Elf64_Rel) */
730 uint64_t *const mloc0 = umalloc(totrelsz>>1);
731 uint64_t * mlocp = mloc0;
732
733 unsigned rel_entsize = 0;
734 unsigned symsec_sh_link = 0;
735
736 for ((relhdr = shdr0), k = nhdr; k; --k, ++relhdr) {
737 char const *const txtname = has64_rel_mcount(relhdr, shdr0,
738 shstrtab, fname);
739 if (txtname) {
740 uint64_t recval = 0;
741 unsigned const recsym = find64_secsym_ndx(
742 w(relhdr->sh_info), txtname, &recval,
743 &shdr0[symsec_sh_link = w(relhdr->sh_link)],
744 ehdr);
745
746 rel_entsize = w8(relhdr->sh_entsize);
747 mlocp = sift64_rel_mcount(mlocp,
748 (void *)mlocp - (void *)mloc0, &mrelp,
749 relhdr, ehdr, recsym, recval, reltype);
750 }
751 }
752 if (mloc0 != mlocp) {
753 append64(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
754 rel_entsize, symsec_sh_link);
755 }
756 free(mrel0);
757 free(mloc0);
758}
759
760static void
761do_file(char const *const fname)
762{
763 Elf32_Ehdr *const ehdr = mmap_file(fname);
764 unsigned int reltype = 0;
765
766 ehdr_curr = ehdr;
767 w = w4nat;
768 w2 = w2nat;
769 w8 = w8nat;
770 switch (ehdr->e_ident[EI_DATA]) {
771 static unsigned int const endian = 1;
772 default: {
773 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
774 ehdr->e_ident[EI_DATA], fname);
775 fail_file();
776 } break;
777 case ELFDATA2LSB: {
778 if (1 != *(unsigned char const *)&endian) {
779 /* main() is big endian, file.o is little endian. */
780 w = w4rev;
781 w2 = w2rev;
782 w8 = w8rev;
783 }
784 } break;
785 case ELFDATA2MSB: {
786 if (0 != *(unsigned char const *)&endian) {
787 /* main() is little endian, file.o is big endian. */
788 w = w4rev;
789 w2 = w2rev;
790 w8 = w8rev;
791 }
792 } break;
793 } /* end switch */
794 if (0 != memcmp(ELFMAG, ehdr->e_ident, SELFMAG)
795 || ET_REL != w2(ehdr->e_type)
796 || EV_CURRENT != ehdr->e_ident[EI_VERSION]) {
797 fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
798 fail_file();
799 }
800
801 gpfx = 0;
802 switch (w2(ehdr->e_machine)) {
803 default: {
804 fprintf(stderr, "unrecognized e_machine %d %s\n",
805 w2(ehdr->e_machine), fname);
806 fail_file();
807 } break;
808 case EM_386: reltype = R_386_32; break;
809 case EM_ARM: reltype = R_ARM_ABS32; break;
810 case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break;
811 case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break;
812 case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break;
813 case EM_S390: /* reltype: e_class */ gpfx = '_'; break;
814 case EM_SH: reltype = R_SH_DIR32; break;
815 case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break;
816 case EM_X86_64: reltype = R_X86_64_64; break;
817 } /* end switch */
818
819 switch (ehdr->e_ident[EI_CLASS]) {
820 default: {
821 fprintf(stderr, "unrecognized ELF class %d %s\n",
822 ehdr->e_ident[EI_CLASS], fname);
823 fail_file();
824 } break;
825 case ELFCLASS32: {
826 if (sizeof(Elf32_Ehdr) != w2(ehdr->e_ehsize)
827 || sizeof(Elf32_Shdr) != w2(ehdr->e_shentsize)) {
828 fprintf(stderr,
829 "unrecognized ET_REL file: %s\n", fname);
830 fail_file();
831 }
832 if (EM_S390 == w2(ehdr->e_machine))
833 reltype = R_390_32;
834 do32(ehdr, fname, reltype);
835 } break;
836 case ELFCLASS64: {
837 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
838 if (sizeof(Elf64_Ehdr) != w2(ghdr->e_ehsize)
839 || sizeof(Elf64_Shdr) != w2(ghdr->e_shentsize)) {
840 fprintf(stderr,
841 "unrecognized ET_REL file: %s\n", fname);
842 fail_file();
843 }
844 if (EM_S390 == w2(ghdr->e_machine))
845 reltype = R_390_64;
846 do64(ghdr, fname, reltype);
847 } break;
848 } /* end switch */
849
850 cleanup();
851}
852
853int
854main(int argc, char const *argv[])
855{
856 int n_error = 0; /* gcc-4.3.0 false positive complaint */
857 if (argc <= 1)
858 fprintf(stderr, "usage: recordmcount file.o...\n");
859 else /* Process each file in turn, allowing deep failure. */
860 for (--argc, ++argv; 0 < argc; --argc, ++argv) {
861 int const sjval = setjmp(jmpenv);
862 switch (sjval) {
863 default: {
864 fprintf(stderr, "internal error: %s\n", argv[0]);
865 exit(1);
866 } break;
867 case SJ_SETJMP: { /* normal sequence */
868 /* Avoid problems if early cleanup() */
869 fd_map = -1;
870 ehdr_curr = NULL;
871 mmap_failed = 1;
872 do_file(argv[0]);
873 } break;
874 case SJ_FAIL: { /* error in do_file or below */
875 ++n_error;
876 } break;
877 case SJ_SUCCEED: { /* premature success */
878 /* do nothing */
879 } break;
880 } /* end switch */
881 }
882 return !!n_error;
883}
884
885
generated by cgit v1.2.2 (git 2.25.0) at 2025-10-27 08:07:12 -0400