blob: 001facfa5b7436b7c5586ed50fec306b09fa5078 [file] [log] [blame]
John Reiser81d38582010-10-13 15:12:54 -04001/*
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>
Steven Rostedtdfad3d52011-04-12 18:53:25 -040027#include <getopt.h>
John Reiser81d38582010-10-13 15:12:54 -040028#include <elf.h>
29#include <fcntl.h>
30#include <setjmp.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <unistd.h>
35
James Hogan00512bd2012-10-05 16:27:31 +010036#ifndef EM_METAG
37/* Remove this when these make it to the standard system elf.h. */
38#define EM_METAG 174
39#define R_METAG_ADDR32 2
40#define R_METAG_NONE 3
41#endif
42
AKASHI Takahiroaf64d2a2014-04-30 10:54:32 +010043#ifndef EM_AARCH64
44#define EM_AARCH64 183
45#define R_AARCH64_ABS64 257
46#endif
47
John Reiser81d38582010-10-13 15:12:54 -040048static int fd_map; /* File descriptor for file being modified. */
49static int mmap_failed; /* Boolean flag. */
50static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
51static char gpfx; /* prefix for global symbol name (sometimes '_') */
52static struct stat sb; /* Remember .st_size, etc. */
53static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
Rabin Vincented604532010-11-30 17:36:48 +010054static const char *altmcount; /* alternate mcount symbol name */
Steven Rostedtdfad3d52011-04-12 18:53:25 -040055static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
John Reiser81d38582010-10-13 15:12:54 -040056
57/* setjmp() return values */
58enum {
59 SJ_SETJMP = 0, /* hardwired first return */
60 SJ_FAIL,
61 SJ_SUCCEED
62};
63
64/* Per-file resource cleanup when multiple files. */
65static void
66cleanup(void)
67{
68 if (!mmap_failed)
69 munmap(ehdr_curr, sb.st_size);
70 else
71 free(ehdr_curr);
72 close(fd_map);
73}
74
75static void __attribute__((noreturn))
76fail_file(void)
77{
78 cleanup();
79 longjmp(jmpenv, SJ_FAIL);
80}
81
82static void __attribute__((noreturn))
83succeed_file(void)
84{
85 cleanup();
86 longjmp(jmpenv, SJ_SUCCEED);
87}
88
89/* ulseek, uread, ...: Check return value for errors. */
90
91static off_t
92ulseek(int const fd, off_t const offset, int const whence)
93{
94 off_t const w = lseek(fd, offset, whence);
Steven Rostedtdd5477f2011-04-06 13:21:17 -040095 if (w == (off_t)-1) {
John Reiser81d38582010-10-13 15:12:54 -040096 perror("lseek");
97 fail_file();
98 }
99 return w;
100}
101
102static size_t
103uread(int const fd, void *const buf, size_t const count)
104{
105 size_t const n = read(fd, buf, count);
106 if (n != count) {
107 perror("read");
108 fail_file();
109 }
110 return n;
111}
112
113static size_t
114uwrite(int const fd, void const *const buf, size_t const count)
115{
116 size_t const n = write(fd, buf, count);
117 if (n != count) {
118 perror("write");
119 fail_file();
120 }
121 return n;
122}
123
124static void *
125umalloc(size_t size)
126{
127 void *const addr = malloc(size);
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400128 if (addr == 0) {
John Reiser81d38582010-10-13 15:12:54 -0400129 fprintf(stderr, "malloc failed: %zu bytes\n", size);
130 fail_file();
131 }
132 return addr;
133}
134
Steven Rostedtffd618f2011-04-08 03:58:48 -0400135static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
136static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
137static unsigned char *ideal_nop;
138
139static char rel_type_nop;
140
141static int (*make_nop)(void *map, size_t const offset);
142
143static int make_nop_x86(void *map, size_t const offset)
144{
145 uint32_t *ptr;
146 unsigned char *op;
147
148 /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
149 ptr = map + offset;
150 if (*ptr != 0)
151 return -1;
152
153 op = map + offset - 1;
154 if (*op != 0xe8)
155 return -1;
156
157 /* convert to nop */
158 ulseek(fd_map, offset - 1, SEEK_SET);
159 uwrite(fd_map, ideal_nop, 5);
160 return 0;
161}
162
John Reiser81d38582010-10-13 15:12:54 -0400163/*
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 */
176static void *mmap_file(char const *fname)
177{
178 void *addr;
179
180 fd_map = open(fname, O_RDWR);
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400181 if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
John Reiser81d38582010-10-13 15:12:54 -0400182 perror(fname);
183 fail_file();
184 }
185 if (!S_ISREG(sb.st_mode)) {
186 fprintf(stderr, "not a regular file: %s\n", fname);
187 fail_file();
188 }
189 addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
190 fd_map, 0);
191 mmap_failed = 0;
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400192 if (addr == MAP_FAILED) {
John Reiser81d38582010-10-13 15:12:54 -0400193 mmap_failed = 1;
194 addr = umalloc(sb.st_size);
195 uread(fd_map, addr, sb.st_size);
196 }
197 return addr;
198}
199
200/* w8rev, w8nat, ...: Handle endianness. */
201
202static uint64_t w8rev(uint64_t const x)
203{
204 return ((0xff & (x >> (0 * 8))) << (7 * 8))
205 | ((0xff & (x >> (1 * 8))) << (6 * 8))
206 | ((0xff & (x >> (2 * 8))) << (5 * 8))
207 | ((0xff & (x >> (3 * 8))) << (4 * 8))
208 | ((0xff & (x >> (4 * 8))) << (3 * 8))
209 | ((0xff & (x >> (5 * 8))) << (2 * 8))
210 | ((0xff & (x >> (6 * 8))) << (1 * 8))
211 | ((0xff & (x >> (7 * 8))) << (0 * 8));
212}
213
214static uint32_t w4rev(uint32_t const x)
215{
216 return ((0xff & (x >> (0 * 8))) << (3 * 8))
217 | ((0xff & (x >> (1 * 8))) << (2 * 8))
218 | ((0xff & (x >> (2 * 8))) << (1 * 8))
219 | ((0xff & (x >> (3 * 8))) << (0 * 8));
220}
221
222static uint32_t w2rev(uint16_t const x)
223{
224 return ((0xff & (x >> (0 * 8))) << (1 * 8))
225 | ((0xff & (x >> (1 * 8))) << (0 * 8));
226}
227
228static uint64_t w8nat(uint64_t const x)
229{
230 return x;
231}
232
233static uint32_t w4nat(uint32_t const x)
234{
235 return x;
236}
237
238static uint32_t w2nat(uint16_t const x)
239{
240 return x;
241}
242
243static uint64_t (*w8)(uint64_t);
244static uint32_t (*w)(uint32_t);
245static uint32_t (*w2)(uint16_t);
246
247/* Names of the sections that could contain calls to mcount. */
248static int
249is_mcounted_section_name(char const *const txtname)
250{
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400251 return strcmp(".text", txtname) == 0 ||
252 strcmp(".ref.text", txtname) == 0 ||
253 strcmp(".sched.text", txtname) == 0 ||
254 strcmp(".spinlock.text", txtname) == 0 ||
255 strcmp(".irqentry.text", txtname) == 0 ||
Steven Rostedt9f087e72011-04-06 14:10:22 -0400256 strcmp(".kprobes.text", txtname) == 0 ||
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400257 strcmp(".text.unlikely", txtname) == 0;
John Reiser81d38582010-10-13 15:12:54 -0400258}
259
Steven Rostedtc28d5072010-10-13 19:06:14 -0400260/* 32 bit and 64 bit are very similar */
261#include "recordmcount.h"
262#define RECORD_MCOUNT_64
263#include "recordmcount.h"
John Reiser81d38582010-10-13 15:12:54 -0400264
John Reisera2d493582010-10-27 18:59:07 +0800265/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
266 * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
267 * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
268 * to imply the order of the members; the spec does not say so.
269 * typedef unsigned char Elf64_Byte;
270 * fails on MIPS64 because their <elf.h> already has it!
271 */
272
273typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */
274
275union mips_r_info {
276 Elf64_Xword r_info;
277 struct {
278 Elf64_Word r_sym; /* Symbol index. */
279 myElf64_Byte r_ssym; /* Special symbol. */
280 myElf64_Byte r_type3; /* Third relocation. */
281 myElf64_Byte r_type2; /* Second relocation. */
282 myElf64_Byte r_type; /* First relocation. */
283 } r_mips;
284};
285
286static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
287{
288 return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
289}
290
291static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
292{
293 rp->r_info = ((union mips_r_info){
294 .r_mips = { .r_sym = w(sym), .r_type = type }
295 }).r_info;
296}
297
John Reiser81d38582010-10-13 15:12:54 -0400298static void
299do_file(char const *const fname)
300{
301 Elf32_Ehdr *const ehdr = mmap_file(fname);
302 unsigned int reltype = 0;
303
304 ehdr_curr = ehdr;
305 w = w4nat;
306 w2 = w2nat;
307 w8 = w8nat;
308 switch (ehdr->e_ident[EI_DATA]) {
309 static unsigned int const endian = 1;
Steven Rostedte90b0c82011-04-06 13:32:24 -0400310 default:
John Reiser81d38582010-10-13 15:12:54 -0400311 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
312 ehdr->e_ident[EI_DATA], fname);
313 fail_file();
Steven Rostedte90b0c82011-04-06 13:32:24 -0400314 break;
315 case ELFDATA2LSB:
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400316 if (*(unsigned char const *)&endian != 1) {
John Reiser81d38582010-10-13 15:12:54 -0400317 /* main() is big endian, file.o is little endian. */
318 w = w4rev;
319 w2 = w2rev;
320 w8 = w8rev;
321 }
Steven Rostedte90b0c82011-04-06 13:32:24 -0400322 break;
323 case ELFDATA2MSB:
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400324 if (*(unsigned char const *)&endian != 0) {
John Reiser81d38582010-10-13 15:12:54 -0400325 /* main() is little endian, file.o is big endian. */
326 w = w4rev;
327 w2 = w2rev;
328 w8 = w8rev;
329 }
Steven Rostedte90b0c82011-04-06 13:32:24 -0400330 break;
John Reiser81d38582010-10-13 15:12:54 -0400331 } /* end switch */
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400332 if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
333 || w2(ehdr->e_type) != ET_REL
334 || ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
John Reiser81d38582010-10-13 15:12:54 -0400335 fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
336 fail_file();
337 }
338
339 gpfx = 0;
340 switch (w2(ehdr->e_machine)) {
Steven Rostedte90b0c82011-04-06 13:32:24 -0400341 default:
John Reiser81d38582010-10-13 15:12:54 -0400342 fprintf(stderr, "unrecognized e_machine %d %s\n",
343 w2(ehdr->e_machine), fname);
344 fail_file();
Steven Rostedte90b0c82011-04-06 13:32:24 -0400345 break;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400346 case EM_386:
347 reltype = R_386_32;
348 make_nop = make_nop_x86;
349 ideal_nop = ideal_nop5_x86_32;
Martin Schwidefsky521ccb52011-05-10 10:10:41 +0200350 mcount_adjust_32 = -1;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400351 break;
Rabin Vincented604532010-11-30 17:36:48 +0100352 case EM_ARM: reltype = R_ARM_ABS32;
353 altmcount = "__gnu_mcount_nc";
354 break;
AKASHI Takahiroaf64d2a2014-04-30 10:54:32 +0100355 case EM_AARCH64:
356 reltype = R_AARCH64_ABS64; gpfx = '_'; break;
John Reiser81d38582010-10-13 15:12:54 -0400357 case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break;
James Hogan00512bd2012-10-05 16:27:31 +0100358 case EM_METAG: reltype = R_METAG_ADDR32;
359 altmcount = "_mcount_wrapper";
360 rel_type_nop = R_METAG_NONE;
361 /* We happen to have the same requirement as MIPS */
362 is_fake_mcount32 = MIPS32_is_fake_mcount;
363 break;
John Reisera2d493582010-10-27 18:59:07 +0800364 case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break;
John Reiser81d38582010-10-13 15:12:54 -0400365 case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break;
366 case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break;
367 case EM_S390: /* reltype: e_class */ gpfx = '_'; break;
368 case EM_SH: reltype = R_SH_DIR32; break;
369 case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400370 case EM_X86_64:
371 make_nop = make_nop_x86;
372 ideal_nop = ideal_nop5_x86_64;
373 reltype = R_X86_64_64;
Martin Schwidefsky521ccb52011-05-10 10:10:41 +0200374 mcount_adjust_64 = -1;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400375 break;
John Reiser81d38582010-10-13 15:12:54 -0400376 } /* end switch */
377
378 switch (ehdr->e_ident[EI_CLASS]) {
Steven Rostedte90b0c82011-04-06 13:32:24 -0400379 default:
John Reiser81d38582010-10-13 15:12:54 -0400380 fprintf(stderr, "unrecognized ELF class %d %s\n",
381 ehdr->e_ident[EI_CLASS], fname);
382 fail_file();
Steven Rostedte90b0c82011-04-06 13:32:24 -0400383 break;
384 case ELFCLASS32:
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400385 if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
386 || w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
John Reiser81d38582010-10-13 15:12:54 -0400387 fprintf(stderr,
388 "unrecognized ET_REL file: %s\n", fname);
389 fail_file();
390 }
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400391 if (w2(ehdr->e_machine) == EM_MIPS) {
John Reisera2d493582010-10-27 18:59:07 +0800392 reltype = R_MIPS_32;
Wu Zhangjin412910c2010-10-27 18:59:08 +0800393 is_fake_mcount32 = MIPS32_is_fake_mcount;
394 }
John Reiser81d38582010-10-13 15:12:54 -0400395 do32(ehdr, fname, reltype);
Steven Rostedte90b0c82011-04-06 13:32:24 -0400396 break;
John Reiser81d38582010-10-13 15:12:54 -0400397 case ELFCLASS64: {
398 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400399 if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
400 || w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
John Reiser81d38582010-10-13 15:12:54 -0400401 fprintf(stderr,
402 "unrecognized ET_REL file: %s\n", fname);
403 fail_file();
404 }
Martin Schwidefskyf2963882011-05-10 10:10:43 +0200405 if (w2(ghdr->e_machine) == EM_S390) {
John Reiser81d38582010-10-13 15:12:54 -0400406 reltype = R_390_64;
Martin Schwidefskyf2963882011-05-10 10:10:43 +0200407 mcount_adjust_64 = -8;
408 }
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400409 if (w2(ghdr->e_machine) == EM_MIPS) {
John Reisera2d493582010-10-27 18:59:07 +0800410 reltype = R_MIPS_64;
411 Elf64_r_sym = MIPS64_r_sym;
412 Elf64_r_info = MIPS64_r_info;
Wu Zhangjin412910c2010-10-27 18:59:08 +0800413 is_fake_mcount64 = MIPS64_is_fake_mcount;
John Reisera2d493582010-10-27 18:59:07 +0800414 }
John Reiser81d38582010-10-13 15:12:54 -0400415 do64(ghdr, fname, reltype);
Steven Rostedte90b0c82011-04-06 13:32:24 -0400416 break;
417 }
John Reiser81d38582010-10-13 15:12:54 -0400418 } /* end switch */
419
420 cleanup();
421}
422
423int
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400424main(int argc, char *argv[])
John Reiser81d38582010-10-13 15:12:54 -0400425{
Rabin Vincentcd3478f2010-11-30 17:33:53 +0100426 const char ftrace[] = "/ftrace.o";
Steven Rostedt44475862010-10-15 11:49:47 -0400427 int ftrace_size = sizeof(ftrace) - 1;
John Reiser81d38582010-10-13 15:12:54 -0400428 int n_error = 0; /* gcc-4.3.0 false positive complaint */
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400429 int c;
430 int i;
Steven Rostedt44475862010-10-15 11:49:47 -0400431
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400432 while ((c = getopt(argc, argv, "w")) >= 0) {
433 switch (c) {
434 case 'w':
435 warn_on_notrace_sect = 1;
436 break;
437 default:
438 fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
439 return 0;
440 }
441 }
442
443 if ((argc - optind) < 1) {
444 fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
Steven Rostedt44475862010-10-15 11:49:47 -0400445 return 0;
446 }
447
448 /* Process each file in turn, allowing deep failure. */
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400449 for (i = optind; i < argc; i++) {
450 char *file = argv[i];
John Reiser81d38582010-10-13 15:12:54 -0400451 int const sjval = setjmp(jmpenv);
Steven Rostedt44475862010-10-15 11:49:47 -0400452 int len;
453
454 /*
455 * The file kernel/trace/ftrace.o references the mcount
456 * function but does not call it. Since ftrace.o should
457 * not be traced anyway, we just skip it.
458 */
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400459 len = strlen(file);
Steven Rostedt44475862010-10-15 11:49:47 -0400460 if (len >= ftrace_size &&
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400461 strcmp(file + (len - ftrace_size), ftrace) == 0)
Steven Rostedt44475862010-10-15 11:49:47 -0400462 continue;
463
John Reiser81d38582010-10-13 15:12:54 -0400464 switch (sjval) {
Steven Rostedte90b0c82011-04-06 13:32:24 -0400465 default:
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400466 fprintf(stderr, "internal error: %s\n", file);
John Reiser81d38582010-10-13 15:12:54 -0400467 exit(1);
Steven Rostedte90b0c82011-04-06 13:32:24 -0400468 break;
469 case SJ_SETJMP: /* normal sequence */
John Reiser81d38582010-10-13 15:12:54 -0400470 /* Avoid problems if early cleanup() */
471 fd_map = -1;
472 ehdr_curr = NULL;
473 mmap_failed = 1;
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400474 do_file(file);
Steven Rostedte90b0c82011-04-06 13:32:24 -0400475 break;
476 case SJ_FAIL: /* error in do_file or below */
John Reiser81d38582010-10-13 15:12:54 -0400477 ++n_error;
Steven Rostedte90b0c82011-04-06 13:32:24 -0400478 break;
479 case SJ_SUCCEED: /* premature success */
John Reiser81d38582010-10-13 15:12:54 -0400480 /* do nothing */
Steven Rostedte90b0c82011-04-06 13:32:24 -0400481 break;
John Reiser81d38582010-10-13 15:12:54 -0400482 } /* end switch */
483 }
484 return !!n_error;
485}