Commit | Line | Data |
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81d3858d JR |
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> | |
dfad3d59 | 27 | #include <getopt.h> |
81d3858d JR |
28 | #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 | ||
00512bdd JH |
36 | #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 | ||
af64d2aa AT |
43 | #ifndef EM_AARCH64 |
44 | #define EM_AARCH64 183 | |
2ee8a74f | 45 | #define R_AARCH64_NONE 0 |
af64d2aa AT |
46 | #define R_AARCH64_ABS64 257 |
47 | #endif | |
48 | ||
81d3858d JR |
49 | static int fd_map; /* File descriptor for file being modified. */ |
50 | static int mmap_failed; /* Boolean flag. */ | |
51 | static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */ | |
52 | static char gpfx; /* prefix for global symbol name (sometimes '_') */ | |
53 | static struct stat sb; /* Remember .st_size, etc. */ | |
54 | static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */ | |
ed60453f | 55 | static const char *altmcount; /* alternate mcount symbol name */ |
dfad3d59 | 56 | static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */ |
81d3858d JR |
57 | |
58 | /* setjmp() return values */ | |
59 | enum { | |
60 | SJ_SETJMP = 0, /* hardwired first return */ | |
61 | SJ_FAIL, | |
62 | SJ_SUCCEED | |
63 | }; | |
64 | ||
65 | /* Per-file resource cleanup when multiple files. */ | |
66 | static void | |
67 | cleanup(void) | |
68 | { | |
69 | if (!mmap_failed) | |
70 | munmap(ehdr_curr, sb.st_size); | |
71 | else | |
72 | free(ehdr_curr); | |
73 | close(fd_map); | |
74 | } | |
75 | ||
76 | static void __attribute__((noreturn)) | |
77 | fail_file(void) | |
78 | { | |
79 | cleanup(); | |
80 | longjmp(jmpenv, SJ_FAIL); | |
81 | } | |
82 | ||
83 | static void __attribute__((noreturn)) | |
84 | succeed_file(void) | |
85 | { | |
86 | cleanup(); | |
87 | longjmp(jmpenv, SJ_SUCCEED); | |
88 | } | |
89 | ||
90 | /* ulseek, uread, ...: Check return value for errors. */ | |
91 | ||
92 | static off_t | |
93 | ulseek(int const fd, off_t const offset, int const whence) | |
94 | { | |
95 | off_t const w = lseek(fd, offset, whence); | |
dd5477ff | 96 | if (w == (off_t)-1) { |
81d3858d JR |
97 | perror("lseek"); |
98 | fail_file(); | |
99 | } | |
100 | return w; | |
101 | } | |
102 | ||
103 | static size_t | |
104 | uread(int const fd, void *const buf, size_t const count) | |
105 | { | |
106 | size_t const n = read(fd, buf, count); | |
107 | if (n != count) { | |
108 | perror("read"); | |
109 | fail_file(); | |
110 | } | |
111 | return n; | |
112 | } | |
113 | ||
114 | static size_t | |
115 | uwrite(int const fd, void const *const buf, size_t const count) | |
116 | { | |
117 | size_t const n = write(fd, buf, count); | |
118 | if (n != count) { | |
119 | perror("write"); | |
120 | fail_file(); | |
121 | } | |
122 | return n; | |
123 | } | |
124 | ||
125 | static void * | |
126 | umalloc(size_t size) | |
127 | { | |
128 | void *const addr = malloc(size); | |
dd5477ff | 129 | if (addr == 0) { |
81d3858d JR |
130 | fprintf(stderr, "malloc failed: %zu bytes\n", size); |
131 | fail_file(); | |
132 | } | |
133 | return addr; | |
134 | } | |
135 | ||
ffd618fa SR |
136 | static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 }; |
137 | static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 }; | |
138 | static unsigned char *ideal_nop; | |
139 | ||
140 | static char rel_type_nop; | |
141 | ||
142 | static int (*make_nop)(void *map, size_t const offset); | |
143 | ||
144 | static int make_nop_x86(void *map, size_t const offset) | |
145 | { | |
146 | uint32_t *ptr; | |
147 | unsigned char *op; | |
148 | ||
149 | /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */ | |
150 | ptr = map + offset; | |
151 | if (*ptr != 0) | |
152 | return -1; | |
153 | ||
154 | op = map + offset - 1; | |
155 | if (*op != 0xe8) | |
156 | return -1; | |
157 | ||
158 | /* convert to nop */ | |
159 | ulseek(fd_map, offset - 1, SEEK_SET); | |
160 | uwrite(fd_map, ideal_nop, 5); | |
161 | return 0; | |
162 | } | |
163 | ||
2ee8a74f LB |
164 | static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5}; |
165 | static int make_nop_arm64(void *map, size_t const offset) | |
166 | { | |
167 | uint32_t *ptr; | |
168 | ||
169 | ptr = map + offset; | |
170 | /* bl <_mcount> is 0x94000000 before relocation */ | |
171 | if (*ptr != 0x94000000) | |
172 | return -1; | |
173 | ||
174 | /* Convert to nop */ | |
175 | ulseek(fd_map, offset, SEEK_SET); | |
176 | uwrite(fd_map, ideal_nop, 4); | |
177 | return 0; | |
178 | } | |
179 | ||
81d3858d JR |
180 | /* |
181 | * Get the whole file as a programming convenience in order to avoid | |
182 | * malloc+lseek+read+free of many pieces. If successful, then mmap | |
183 | * avoids copying unused pieces; else just read the whole file. | |
184 | * Open for both read and write; new info will be appended to the file. | |
185 | * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr | |
186 | * do not propagate to the file until an explicit overwrite at the last. | |
187 | * This preserves most aspects of consistency (all except .st_size) | |
188 | * for simultaneous readers of the file while we are appending to it. | |
189 | * However, multiple writers still are bad. We choose not to use | |
190 | * locking because it is expensive and the use case of kernel build | |
191 | * makes multiple writers unlikely. | |
192 | */ | |
193 | static void *mmap_file(char const *fname) | |
194 | { | |
195 | void *addr; | |
196 | ||
197 | fd_map = open(fname, O_RDWR); | |
dd5477ff | 198 | if (fd_map < 0 || fstat(fd_map, &sb) < 0) { |
81d3858d JR |
199 | perror(fname); |
200 | fail_file(); | |
201 | } | |
202 | if (!S_ISREG(sb.st_mode)) { | |
203 | fprintf(stderr, "not a regular file: %s\n", fname); | |
204 | fail_file(); | |
205 | } | |
206 | addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, | |
207 | fd_map, 0); | |
208 | mmap_failed = 0; | |
dd5477ff | 209 | if (addr == MAP_FAILED) { |
81d3858d JR |
210 | mmap_failed = 1; |
211 | addr = umalloc(sb.st_size); | |
212 | uread(fd_map, addr, sb.st_size); | |
213 | } | |
214 | return addr; | |
215 | } | |
216 | ||
217 | /* w8rev, w8nat, ...: Handle endianness. */ | |
218 | ||
219 | static uint64_t w8rev(uint64_t const x) | |
220 | { | |
221 | return ((0xff & (x >> (0 * 8))) << (7 * 8)) | |
222 | | ((0xff & (x >> (1 * 8))) << (6 * 8)) | |
223 | | ((0xff & (x >> (2 * 8))) << (5 * 8)) | |
224 | | ((0xff & (x >> (3 * 8))) << (4 * 8)) | |
225 | | ((0xff & (x >> (4 * 8))) << (3 * 8)) | |
226 | | ((0xff & (x >> (5 * 8))) << (2 * 8)) | |
227 | | ((0xff & (x >> (6 * 8))) << (1 * 8)) | |
228 | | ((0xff & (x >> (7 * 8))) << (0 * 8)); | |
229 | } | |
230 | ||
231 | static uint32_t w4rev(uint32_t const x) | |
232 | { | |
233 | return ((0xff & (x >> (0 * 8))) << (3 * 8)) | |
234 | | ((0xff & (x >> (1 * 8))) << (2 * 8)) | |
235 | | ((0xff & (x >> (2 * 8))) << (1 * 8)) | |
236 | | ((0xff & (x >> (3 * 8))) << (0 * 8)); | |
237 | } | |
238 | ||
239 | static uint32_t w2rev(uint16_t const x) | |
240 | { | |
241 | return ((0xff & (x >> (0 * 8))) << (1 * 8)) | |
242 | | ((0xff & (x >> (1 * 8))) << (0 * 8)); | |
243 | } | |
244 | ||
245 | static uint64_t w8nat(uint64_t const x) | |
246 | { | |
247 | return x; | |
248 | } | |
249 | ||
250 | static uint32_t w4nat(uint32_t const x) | |
251 | { | |
252 | return x; | |
253 | } | |
254 | ||
255 | static uint32_t w2nat(uint16_t const x) | |
256 | { | |
257 | return x; | |
258 | } | |
259 | ||
260 | static uint64_t (*w8)(uint64_t); | |
261 | static uint32_t (*w)(uint32_t); | |
262 | static uint32_t (*w2)(uint16_t); | |
263 | ||
264 | /* Names of the sections that could contain calls to mcount. */ | |
265 | static int | |
266 | is_mcounted_section_name(char const *const txtname) | |
267 | { | |
dd5477ff SR |
268 | return strcmp(".text", txtname) == 0 || |
269 | strcmp(".ref.text", txtname) == 0 || | |
270 | strcmp(".sched.text", txtname) == 0 || | |
271 | strcmp(".spinlock.text", txtname) == 0 || | |
272 | strcmp(".irqentry.text", txtname) == 0 || | |
9f087e76 | 273 | strcmp(".kprobes.text", txtname) == 0 || |
dd5477ff | 274 | strcmp(".text.unlikely", txtname) == 0; |
81d3858d JR |
275 | } |
276 | ||
c28d5077 SR |
277 | /* 32 bit and 64 bit are very similar */ |
278 | #include "recordmcount.h" | |
279 | #define RECORD_MCOUNT_64 | |
280 | #include "recordmcount.h" | |
81d3858d | 281 | |
a2d49358 JR |
282 | /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. |
283 | * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf | |
284 | * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] | |
285 | * to imply the order of the members; the spec does not say so. | |
286 | * typedef unsigned char Elf64_Byte; | |
287 | * fails on MIPS64 because their <elf.h> already has it! | |
288 | */ | |
289 | ||
290 | typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */ | |
291 | ||
292 | union mips_r_info { | |
293 | Elf64_Xword r_info; | |
294 | struct { | |
295 | Elf64_Word r_sym; /* Symbol index. */ | |
296 | myElf64_Byte r_ssym; /* Special symbol. */ | |
297 | myElf64_Byte r_type3; /* Third relocation. */ | |
298 | myElf64_Byte r_type2; /* Second relocation. */ | |
299 | myElf64_Byte r_type; /* First relocation. */ | |
300 | } r_mips; | |
301 | }; | |
302 | ||
303 | static uint64_t MIPS64_r_sym(Elf64_Rel const *rp) | |
304 | { | |
305 | return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym); | |
306 | } | |
307 | ||
308 | static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type) | |
309 | { | |
310 | rp->r_info = ((union mips_r_info){ | |
311 | .r_mips = { .r_sym = w(sym), .r_type = type } | |
312 | }).r_info; | |
313 | } | |
314 | ||
81d3858d JR |
315 | static void |
316 | do_file(char const *const fname) | |
317 | { | |
318 | Elf32_Ehdr *const ehdr = mmap_file(fname); | |
319 | unsigned int reltype = 0; | |
320 | ||
321 | ehdr_curr = ehdr; | |
322 | w = w4nat; | |
323 | w2 = w2nat; | |
324 | w8 = w8nat; | |
325 | switch (ehdr->e_ident[EI_DATA]) { | |
326 | static unsigned int const endian = 1; | |
e90b0c8b | 327 | default: |
81d3858d JR |
328 | fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", |
329 | ehdr->e_ident[EI_DATA], fname); | |
330 | fail_file(); | |
e90b0c8b SR |
331 | break; |
332 | case ELFDATA2LSB: | |
dd5477ff | 333 | if (*(unsigned char const *)&endian != 1) { |
81d3858d JR |
334 | /* main() is big endian, file.o is little endian. */ |
335 | w = w4rev; | |
336 | w2 = w2rev; | |
337 | w8 = w8rev; | |
338 | } | |
e90b0c8b SR |
339 | break; |
340 | case ELFDATA2MSB: | |
dd5477ff | 341 | if (*(unsigned char const *)&endian != 0) { |
81d3858d JR |
342 | /* main() is little endian, file.o is big endian. */ |
343 | w = w4rev; | |
344 | w2 = w2rev; | |
345 | w8 = w8rev; | |
346 | } | |
e90b0c8b | 347 | break; |
81d3858d | 348 | } /* end switch */ |
dd5477ff SR |
349 | if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 |
350 | || w2(ehdr->e_type) != ET_REL | |
351 | || ehdr->e_ident[EI_VERSION] != EV_CURRENT) { | |
81d3858d JR |
352 | fprintf(stderr, "unrecognized ET_REL file %s\n", fname); |
353 | fail_file(); | |
354 | } | |
355 | ||
356 | gpfx = 0; | |
357 | switch (w2(ehdr->e_machine)) { | |
e90b0c8b | 358 | default: |
81d3858d JR |
359 | fprintf(stderr, "unrecognized e_machine %d %s\n", |
360 | w2(ehdr->e_machine), fname); | |
361 | fail_file(); | |
e90b0c8b | 362 | break; |
ffd618fa SR |
363 | case EM_386: |
364 | reltype = R_386_32; | |
46a2b61e | 365 | rel_type_nop = R_386_NONE; |
ffd618fa SR |
366 | make_nop = make_nop_x86; |
367 | ideal_nop = ideal_nop5_x86_32; | |
521ccb5c | 368 | mcount_adjust_32 = -1; |
ffd618fa | 369 | break; |
ed60453f RV |
370 | case EM_ARM: reltype = R_ARM_ABS32; |
371 | altmcount = "__gnu_mcount_nc"; | |
372 | break; | |
af64d2aa | 373 | case EM_AARCH64: |
2ee8a74f LB |
374 | reltype = R_AARCH64_ABS64; |
375 | make_nop = make_nop_arm64; | |
376 | rel_type_nop = R_AARCH64_NONE; | |
377 | ideal_nop = ideal_nop4_arm64; | |
378 | gpfx = '_'; | |
379 | break; | |
81d3858d | 380 | case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break; |
00512bdd JH |
381 | case EM_METAG: reltype = R_METAG_ADDR32; |
382 | altmcount = "_mcount_wrapper"; | |
383 | rel_type_nop = R_METAG_NONE; | |
384 | /* We happen to have the same requirement as MIPS */ | |
385 | is_fake_mcount32 = MIPS32_is_fake_mcount; | |
386 | break; | |
a2d49358 | 387 | case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break; |
81d3858d JR |
388 | case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break; |
389 | case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break; | |
390 | case EM_S390: /* reltype: e_class */ gpfx = '_'; break; | |
391 | case EM_SH: reltype = R_SH_DIR32; break; | |
392 | case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break; | |
ffd618fa SR |
393 | case EM_X86_64: |
394 | make_nop = make_nop_x86; | |
395 | ideal_nop = ideal_nop5_x86_64; | |
396 | reltype = R_X86_64_64; | |
46a2b61e | 397 | rel_type_nop = R_X86_64_NONE; |
521ccb5c | 398 | mcount_adjust_64 = -1; |
ffd618fa | 399 | break; |
81d3858d JR |
400 | } /* end switch */ |
401 | ||
402 | switch (ehdr->e_ident[EI_CLASS]) { | |
e90b0c8b | 403 | default: |
81d3858d JR |
404 | fprintf(stderr, "unrecognized ELF class %d %s\n", |
405 | ehdr->e_ident[EI_CLASS], fname); | |
406 | fail_file(); | |
e90b0c8b SR |
407 | break; |
408 | case ELFCLASS32: | |
dd5477ff SR |
409 | if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr) |
410 | || w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) { | |
81d3858d JR |
411 | fprintf(stderr, |
412 | "unrecognized ET_REL file: %s\n", fname); | |
413 | fail_file(); | |
414 | } | |
dd5477ff | 415 | if (w2(ehdr->e_machine) == EM_MIPS) { |
a2d49358 | 416 | reltype = R_MIPS_32; |
412910cd WZ |
417 | is_fake_mcount32 = MIPS32_is_fake_mcount; |
418 | } | |
81d3858d | 419 | do32(ehdr, fname, reltype); |
e90b0c8b | 420 | break; |
81d3858d JR |
421 | case ELFCLASS64: { |
422 | Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr; | |
dd5477ff SR |
423 | if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr) |
424 | || w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) { | |
81d3858d JR |
425 | fprintf(stderr, |
426 | "unrecognized ET_REL file: %s\n", fname); | |
427 | fail_file(); | |
428 | } | |
f2963886 | 429 | if (w2(ghdr->e_machine) == EM_S390) { |
81d3858d | 430 | reltype = R_390_64; |
c933146a | 431 | mcount_adjust_64 = -14; |
f2963886 | 432 | } |
dd5477ff | 433 | if (w2(ghdr->e_machine) == EM_MIPS) { |
a2d49358 JR |
434 | reltype = R_MIPS_64; |
435 | Elf64_r_sym = MIPS64_r_sym; | |
436 | Elf64_r_info = MIPS64_r_info; | |
412910cd | 437 | is_fake_mcount64 = MIPS64_is_fake_mcount; |
a2d49358 | 438 | } |
81d3858d | 439 | do64(ghdr, fname, reltype); |
e90b0c8b SR |
440 | break; |
441 | } | |
81d3858d JR |
442 | } /* end switch */ |
443 | ||
444 | cleanup(); | |
445 | } | |
446 | ||
447 | int | |
dfad3d59 | 448 | main(int argc, char *argv[]) |
81d3858d | 449 | { |
cd3478f2 | 450 | const char ftrace[] = "/ftrace.o"; |
44475863 | 451 | int ftrace_size = sizeof(ftrace) - 1; |
81d3858d | 452 | int n_error = 0; /* gcc-4.3.0 false positive complaint */ |
dfad3d59 SR |
453 | int c; |
454 | int i; | |
44475863 | 455 | |
dfad3d59 SR |
456 | while ((c = getopt(argc, argv, "w")) >= 0) { |
457 | switch (c) { | |
458 | case 'w': | |
459 | warn_on_notrace_sect = 1; | |
460 | break; | |
461 | default: | |
462 | fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); | |
463 | return 0; | |
464 | } | |
465 | } | |
466 | ||
467 | if ((argc - optind) < 1) { | |
468 | fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); | |
44475863 SR |
469 | return 0; |
470 | } | |
471 | ||
472 | /* Process each file in turn, allowing deep failure. */ | |
dfad3d59 SR |
473 | for (i = optind; i < argc; i++) { |
474 | char *file = argv[i]; | |
81d3858d | 475 | int const sjval = setjmp(jmpenv); |
44475863 SR |
476 | int len; |
477 | ||
478 | /* | |
479 | * The file kernel/trace/ftrace.o references the mcount | |
480 | * function but does not call it. Since ftrace.o should | |
481 | * not be traced anyway, we just skip it. | |
482 | */ | |
dfad3d59 | 483 | len = strlen(file); |
44475863 | 484 | if (len >= ftrace_size && |
dfad3d59 | 485 | strcmp(file + (len - ftrace_size), ftrace) == 0) |
44475863 SR |
486 | continue; |
487 | ||
81d3858d | 488 | switch (sjval) { |
e90b0c8b | 489 | default: |
dfad3d59 | 490 | fprintf(stderr, "internal error: %s\n", file); |
81d3858d | 491 | exit(1); |
e90b0c8b SR |
492 | break; |
493 | case SJ_SETJMP: /* normal sequence */ | |
81d3858d JR |
494 | /* Avoid problems if early cleanup() */ |
495 | fd_map = -1; | |
496 | ehdr_curr = NULL; | |
497 | mmap_failed = 1; | |
dfad3d59 | 498 | do_file(file); |
e90b0c8b SR |
499 | break; |
500 | case SJ_FAIL: /* error in do_file or below */ | |
81d3858d | 501 | ++n_error; |
e90b0c8b SR |
502 | break; |
503 | case SJ_SUCCEED: /* premature success */ | |
81d3858d | 504 | /* do nothing */ |
e90b0c8b | 505 | break; |
81d3858d JR |
506 | } /* end switch */ |
507 | } | |
508 | return !!n_error; | |
509 | } |