Commit | Line | Data |
---|---|---|
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 | ||
3e6afa42 LA |
36 | /* |
37 | * glibc synced up and added the metag number but didn't add the relocations. | |
38 | * Work around this in a crude manner for now. | |
39 | */ | |
00512bdd | 40 | #ifndef EM_METAG |
00512bdd | 41 | #define EM_METAG 174 |
3e6afa42 LA |
42 | #endif |
43 | #ifndef R_METAG_ADDR32 | |
00512bdd | 44 | #define R_METAG_ADDR32 2 |
3e6afa42 LA |
45 | #endif |
46 | #ifndef R_METAG_NONE | |
00512bdd JH |
47 | #define R_METAG_NONE 3 |
48 | #endif | |
49 | ||
6fa3eb70 S |
50 | #ifndef EM_AARCH64 |
51 | #define EM_AARCH64 183 | |
52 | #define R_AARCH64_ABS64 257 | |
53 | #endif | |
54 | ||
81d3858d JR |
55 | static int fd_map; /* File descriptor for file being modified. */ |
56 | static int mmap_failed; /* Boolean flag. */ | |
57 | static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */ | |
58 | static char gpfx; /* prefix for global symbol name (sometimes '_') */ | |
59 | static struct stat sb; /* Remember .st_size, etc. */ | |
60 | static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */ | |
ed60453f | 61 | static const char *altmcount; /* alternate mcount symbol name */ |
dfad3d59 | 62 | static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */ |
81d3858d JR |
63 | |
64 | /* setjmp() return values */ | |
65 | enum { | |
66 | SJ_SETJMP = 0, /* hardwired first return */ | |
67 | SJ_FAIL, | |
68 | SJ_SUCCEED | |
69 | }; | |
70 | ||
71 | /* Per-file resource cleanup when multiple files. */ | |
72 | static void | |
73 | cleanup(void) | |
74 | { | |
75 | if (!mmap_failed) | |
76 | munmap(ehdr_curr, sb.st_size); | |
77 | else | |
78 | free(ehdr_curr); | |
79 | close(fd_map); | |
80 | } | |
81 | ||
82 | static void __attribute__((noreturn)) | |
83 | fail_file(void) | |
84 | { | |
85 | cleanup(); | |
86 | longjmp(jmpenv, SJ_FAIL); | |
87 | } | |
88 | ||
89 | static void __attribute__((noreturn)) | |
90 | succeed_file(void) | |
91 | { | |
92 | cleanup(); | |
93 | longjmp(jmpenv, SJ_SUCCEED); | |
94 | } | |
95 | ||
96 | /* ulseek, uread, ...: Check return value for errors. */ | |
97 | ||
98 | static off_t | |
99 | ulseek(int const fd, off_t const offset, int const whence) | |
100 | { | |
101 | off_t const w = lseek(fd, offset, whence); | |
dd5477ff | 102 | if (w == (off_t)-1) { |
81d3858d JR |
103 | perror("lseek"); |
104 | fail_file(); | |
105 | } | |
106 | return w; | |
107 | } | |
108 | ||
109 | static size_t | |
110 | uread(int const fd, void *const buf, size_t const count) | |
111 | { | |
112 | size_t const n = read(fd, buf, count); | |
113 | if (n != count) { | |
114 | perror("read"); | |
115 | fail_file(); | |
116 | } | |
117 | return n; | |
118 | } | |
119 | ||
120 | static size_t | |
121 | uwrite(int const fd, void const *const buf, size_t const count) | |
122 | { | |
123 | size_t const n = write(fd, buf, count); | |
124 | if (n != count) { | |
125 | perror("write"); | |
126 | fail_file(); | |
127 | } | |
128 | return n; | |
129 | } | |
130 | ||
131 | static void * | |
132 | umalloc(size_t size) | |
133 | { | |
134 | void *const addr = malloc(size); | |
dd5477ff | 135 | if (addr == 0) { |
81d3858d JR |
136 | fprintf(stderr, "malloc failed: %zu bytes\n", size); |
137 | fail_file(); | |
138 | } | |
139 | return addr; | |
140 | } | |
141 | ||
ffd618fa SR |
142 | static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 }; |
143 | static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 }; | |
144 | static unsigned char *ideal_nop; | |
145 | ||
146 | static char rel_type_nop; | |
147 | ||
148 | static int (*make_nop)(void *map, size_t const offset); | |
149 | ||
150 | static int make_nop_x86(void *map, size_t const offset) | |
151 | { | |
152 | uint32_t *ptr; | |
153 | unsigned char *op; | |
154 | ||
155 | /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */ | |
156 | ptr = map + offset; | |
157 | if (*ptr != 0) | |
158 | return -1; | |
159 | ||
160 | op = map + offset - 1; | |
161 | if (*op != 0xe8) | |
162 | return -1; | |
163 | ||
164 | /* convert to nop */ | |
165 | ulseek(fd_map, offset - 1, SEEK_SET); | |
166 | uwrite(fd_map, ideal_nop, 5); | |
167 | return 0; | |
168 | } | |
169 | ||
81d3858d JR |
170 | /* |
171 | * Get the whole file as a programming convenience in order to avoid | |
172 | * malloc+lseek+read+free of many pieces. If successful, then mmap | |
173 | * avoids copying unused pieces; else just read the whole file. | |
174 | * Open for both read and write; new info will be appended to the file. | |
175 | * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr | |
176 | * do not propagate to the file until an explicit overwrite at the last. | |
177 | * This preserves most aspects of consistency (all except .st_size) | |
178 | * for simultaneous readers of the file while we are appending to it. | |
179 | * However, multiple writers still are bad. We choose not to use | |
180 | * locking because it is expensive and the use case of kernel build | |
181 | * makes multiple writers unlikely. | |
182 | */ | |
183 | static void *mmap_file(char const *fname) | |
184 | { | |
185 | void *addr; | |
186 | ||
187 | fd_map = open(fname, O_RDWR); | |
dd5477ff | 188 | if (fd_map < 0 || fstat(fd_map, &sb) < 0) { |
81d3858d JR |
189 | perror(fname); |
190 | fail_file(); | |
191 | } | |
192 | if (!S_ISREG(sb.st_mode)) { | |
193 | fprintf(stderr, "not a regular file: %s\n", fname); | |
194 | fail_file(); | |
195 | } | |
196 | addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, | |
197 | fd_map, 0); | |
198 | mmap_failed = 0; | |
dd5477ff | 199 | if (addr == MAP_FAILED) { |
81d3858d JR |
200 | mmap_failed = 1; |
201 | addr = umalloc(sb.st_size); | |
202 | uread(fd_map, addr, sb.st_size); | |
203 | } | |
099e9d4f RK |
204 | if (sb.st_nlink != 1) { |
205 | /* file is hard-linked, break the hard link */ | |
206 | close(fd_map); | |
207 | if (unlink(fname) < 0) { | |
208 | perror(fname); | |
209 | fail_file(); | |
210 | } | |
211 | fd_map = open(fname, O_RDWR | O_CREAT, sb.st_mode); | |
212 | if (fd_map < 0) { | |
213 | perror(fname); | |
214 | fail_file(); | |
215 | } | |
216 | uwrite(fd_map, addr, sb.st_size); | |
217 | } | |
81d3858d JR |
218 | return addr; |
219 | } | |
220 | ||
221 | /* w8rev, w8nat, ...: Handle endianness. */ | |
222 | ||
223 | static uint64_t w8rev(uint64_t const x) | |
224 | { | |
225 | return ((0xff & (x >> (0 * 8))) << (7 * 8)) | |
226 | | ((0xff & (x >> (1 * 8))) << (6 * 8)) | |
227 | | ((0xff & (x >> (2 * 8))) << (5 * 8)) | |
228 | | ((0xff & (x >> (3 * 8))) << (4 * 8)) | |
229 | | ((0xff & (x >> (4 * 8))) << (3 * 8)) | |
230 | | ((0xff & (x >> (5 * 8))) << (2 * 8)) | |
231 | | ((0xff & (x >> (6 * 8))) << (1 * 8)) | |
232 | | ((0xff & (x >> (7 * 8))) << (0 * 8)); | |
233 | } | |
234 | ||
235 | static uint32_t w4rev(uint32_t const x) | |
236 | { | |
237 | return ((0xff & (x >> (0 * 8))) << (3 * 8)) | |
238 | | ((0xff & (x >> (1 * 8))) << (2 * 8)) | |
239 | | ((0xff & (x >> (2 * 8))) << (1 * 8)) | |
240 | | ((0xff & (x >> (3 * 8))) << (0 * 8)); | |
241 | } | |
242 | ||
243 | static uint32_t w2rev(uint16_t const x) | |
244 | { | |
245 | return ((0xff & (x >> (0 * 8))) << (1 * 8)) | |
246 | | ((0xff & (x >> (1 * 8))) << (0 * 8)); | |
247 | } | |
248 | ||
249 | static uint64_t w8nat(uint64_t const x) | |
250 | { | |
251 | return x; | |
252 | } | |
253 | ||
254 | static uint32_t w4nat(uint32_t const x) | |
255 | { | |
256 | return x; | |
257 | } | |
258 | ||
259 | static uint32_t w2nat(uint16_t const x) | |
260 | { | |
261 | return x; | |
262 | } | |
263 | ||
264 | static uint64_t (*w8)(uint64_t); | |
265 | static uint32_t (*w)(uint32_t); | |
266 | static uint32_t (*w2)(uint16_t); | |
267 | ||
268 | /* Names of the sections that could contain calls to mcount. */ | |
269 | static int | |
270 | is_mcounted_section_name(char const *const txtname) | |
271 | { | |
dd5477ff SR |
272 | return strcmp(".text", txtname) == 0 || |
273 | strcmp(".ref.text", txtname) == 0 || | |
274 | strcmp(".sched.text", txtname) == 0 || | |
275 | strcmp(".spinlock.text", txtname) == 0 || | |
276 | strcmp(".irqentry.text", txtname) == 0 || | |
9f087e76 | 277 | strcmp(".kprobes.text", txtname) == 0 || |
dd5477ff | 278 | strcmp(".text.unlikely", txtname) == 0; |
81d3858d JR |
279 | } |
280 | ||
c28d5077 SR |
281 | /* 32 bit and 64 bit are very similar */ |
282 | #include "recordmcount.h" | |
283 | #define RECORD_MCOUNT_64 | |
284 | #include "recordmcount.h" | |
81d3858d | 285 | |
a2d49358 JR |
286 | /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. |
287 | * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf | |
288 | * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] | |
289 | * to imply the order of the members; the spec does not say so. | |
290 | * typedef unsigned char Elf64_Byte; | |
291 | * fails on MIPS64 because their <elf.h> already has it! | |
292 | */ | |
293 | ||
294 | typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */ | |
295 | ||
296 | union mips_r_info { | |
297 | Elf64_Xword r_info; | |
298 | struct { | |
299 | Elf64_Word r_sym; /* Symbol index. */ | |
300 | myElf64_Byte r_ssym; /* Special symbol. */ | |
301 | myElf64_Byte r_type3; /* Third relocation. */ | |
302 | myElf64_Byte r_type2; /* Second relocation. */ | |
303 | myElf64_Byte r_type; /* First relocation. */ | |
304 | } r_mips; | |
305 | }; | |
306 | ||
307 | static uint64_t MIPS64_r_sym(Elf64_Rel const *rp) | |
308 | { | |
309 | return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym); | |
310 | } | |
311 | ||
312 | static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type) | |
313 | { | |
314 | rp->r_info = ((union mips_r_info){ | |
315 | .r_mips = { .r_sym = w(sym), .r_type = type } | |
316 | }).r_info; | |
317 | } | |
318 | ||
81d3858d JR |
319 | static void |
320 | do_file(char const *const fname) | |
321 | { | |
322 | Elf32_Ehdr *const ehdr = mmap_file(fname); | |
323 | unsigned int reltype = 0; | |
324 | ||
325 | ehdr_curr = ehdr; | |
326 | w = w4nat; | |
327 | w2 = w2nat; | |
328 | w8 = w8nat; | |
329 | switch (ehdr->e_ident[EI_DATA]) { | |
330 | static unsigned int const endian = 1; | |
e90b0c8b | 331 | default: |
81d3858d JR |
332 | fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", |
333 | ehdr->e_ident[EI_DATA], fname); | |
334 | fail_file(); | |
e90b0c8b SR |
335 | break; |
336 | case ELFDATA2LSB: | |
dd5477ff | 337 | if (*(unsigned char const *)&endian != 1) { |
81d3858d JR |
338 | /* main() is big endian, file.o is little endian. */ |
339 | w = w4rev; | |
340 | w2 = w2rev; | |
341 | w8 = w8rev; | |
342 | } | |
e90b0c8b SR |
343 | break; |
344 | case ELFDATA2MSB: | |
dd5477ff | 345 | if (*(unsigned char const *)&endian != 0) { |
81d3858d JR |
346 | /* main() is little endian, file.o is big endian. */ |
347 | w = w4rev; | |
348 | w2 = w2rev; | |
349 | w8 = w8rev; | |
350 | } | |
e90b0c8b | 351 | break; |
81d3858d | 352 | } /* end switch */ |
dd5477ff SR |
353 | if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 |
354 | || w2(ehdr->e_type) != ET_REL | |
355 | || ehdr->e_ident[EI_VERSION] != EV_CURRENT) { | |
81d3858d JR |
356 | fprintf(stderr, "unrecognized ET_REL file %s\n", fname); |
357 | fail_file(); | |
358 | } | |
359 | ||
360 | gpfx = 0; | |
361 | switch (w2(ehdr->e_machine)) { | |
e90b0c8b | 362 | default: |
81d3858d JR |
363 | fprintf(stderr, "unrecognized e_machine %d %s\n", |
364 | w2(ehdr->e_machine), fname); | |
365 | fail_file(); | |
e90b0c8b | 366 | break; |
ffd618fa SR |
367 | case EM_386: |
368 | reltype = R_386_32; | |
369 | make_nop = make_nop_x86; | |
370 | ideal_nop = ideal_nop5_x86_32; | |
521ccb5c | 371 | mcount_adjust_32 = -1; |
ffd618fa | 372 | break; |
ed60453f RV |
373 | case EM_ARM: reltype = R_ARM_ABS32; |
374 | altmcount = "__gnu_mcount_nc"; | |
375 | break; | |
6fa3eb70 S |
376 | case EM_AARCH64: |
377 | reltype = R_AARCH64_ABS64; gpfx = '_'; break; | |
81d3858d | 378 | case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break; |
00512bdd JH |
379 | case EM_METAG: reltype = R_METAG_ADDR32; |
380 | altmcount = "_mcount_wrapper"; | |
381 | rel_type_nop = R_METAG_NONE; | |
382 | /* We happen to have the same requirement as MIPS */ | |
383 | is_fake_mcount32 = MIPS32_is_fake_mcount; | |
384 | break; | |
a2d49358 | 385 | case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break; |
81d3858d JR |
386 | case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break; |
387 | case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break; | |
388 | case EM_S390: /* reltype: e_class */ gpfx = '_'; break; | |
389 | case EM_SH: reltype = R_SH_DIR32; break; | |
390 | case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break; | |
ffd618fa SR |
391 | case EM_X86_64: |
392 | make_nop = make_nop_x86; | |
393 | ideal_nop = ideal_nop5_x86_64; | |
394 | reltype = R_X86_64_64; | |
521ccb5c | 395 | mcount_adjust_64 = -1; |
ffd618fa | 396 | break; |
81d3858d JR |
397 | } /* end switch */ |
398 | ||
399 | switch (ehdr->e_ident[EI_CLASS]) { | |
e90b0c8b | 400 | default: |
81d3858d JR |
401 | fprintf(stderr, "unrecognized ELF class %d %s\n", |
402 | ehdr->e_ident[EI_CLASS], fname); | |
403 | fail_file(); | |
e90b0c8b SR |
404 | break; |
405 | case ELFCLASS32: | |
dd5477ff SR |
406 | if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr) |
407 | || w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) { | |
81d3858d JR |
408 | fprintf(stderr, |
409 | "unrecognized ET_REL file: %s\n", fname); | |
410 | fail_file(); | |
411 | } | |
f2963886 | 412 | if (w2(ehdr->e_machine) == EM_S390) { |
81d3858d | 413 | reltype = R_390_32; |
f2963886 MS |
414 | mcount_adjust_32 = -4; |
415 | } | |
dd5477ff | 416 | if (w2(ehdr->e_machine) == EM_MIPS) { |
a2d49358 | 417 | reltype = R_MIPS_32; |
412910cd WZ |
418 | is_fake_mcount32 = MIPS32_is_fake_mcount; |
419 | } | |
81d3858d | 420 | do32(ehdr, fname, reltype); |
e90b0c8b | 421 | break; |
81d3858d JR |
422 | case ELFCLASS64: { |
423 | Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr; | |
dd5477ff SR |
424 | if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr) |
425 | || w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) { | |
81d3858d JR |
426 | fprintf(stderr, |
427 | "unrecognized ET_REL file: %s\n", fname); | |
428 | fail_file(); | |
429 | } | |
f2963886 | 430 | if (w2(ghdr->e_machine) == EM_S390) { |
81d3858d | 431 | reltype = R_390_64; |
f2963886 MS |
432 | mcount_adjust_64 = -8; |
433 | } | |
dd5477ff | 434 | if (w2(ghdr->e_machine) == EM_MIPS) { |
a2d49358 JR |
435 | reltype = R_MIPS_64; |
436 | Elf64_r_sym = MIPS64_r_sym; | |
437 | Elf64_r_info = MIPS64_r_info; | |
412910cd | 438 | is_fake_mcount64 = MIPS64_is_fake_mcount; |
a2d49358 | 439 | } |
81d3858d | 440 | do64(ghdr, fname, reltype); |
e90b0c8b SR |
441 | break; |
442 | } | |
81d3858d JR |
443 | } /* end switch */ |
444 | ||
445 | cleanup(); | |
446 | } | |
447 | ||
448 | int | |
dfad3d59 | 449 | main(int argc, char *argv[]) |
81d3858d | 450 | { |
cd3478f2 | 451 | const char ftrace[] = "/ftrace.o"; |
44475863 | 452 | int ftrace_size = sizeof(ftrace) - 1; |
81d3858d | 453 | int n_error = 0; /* gcc-4.3.0 false positive complaint */ |
dfad3d59 SR |
454 | int c; |
455 | int i; | |
44475863 | 456 | |
dfad3d59 SR |
457 | while ((c = getopt(argc, argv, "w")) >= 0) { |
458 | switch (c) { | |
459 | case 'w': | |
460 | warn_on_notrace_sect = 1; | |
461 | break; | |
462 | default: | |
463 | fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); | |
464 | return 0; | |
465 | } | |
466 | } | |
467 | ||
468 | if ((argc - optind) < 1) { | |
469 | fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); | |
44475863 SR |
470 | return 0; |
471 | } | |
472 | ||
473 | /* Process each file in turn, allowing deep failure. */ | |
dfad3d59 SR |
474 | for (i = optind; i < argc; i++) { |
475 | char *file = argv[i]; | |
81d3858d | 476 | int const sjval = setjmp(jmpenv); |
44475863 SR |
477 | int len; |
478 | ||
479 | /* | |
480 | * The file kernel/trace/ftrace.o references the mcount | |
481 | * function but does not call it. Since ftrace.o should | |
482 | * not be traced anyway, we just skip it. | |
483 | */ | |
dfad3d59 | 484 | len = strlen(file); |
44475863 | 485 | if (len >= ftrace_size && |
dfad3d59 | 486 | strcmp(file + (len - ftrace_size), ftrace) == 0) |
44475863 SR |
487 | continue; |
488 | ||
81d3858d | 489 | switch (sjval) { |
e90b0c8b | 490 | default: |
dfad3d59 | 491 | fprintf(stderr, "internal error: %s\n", file); |
81d3858d | 492 | exit(1); |
e90b0c8b SR |
493 | break; |
494 | case SJ_SETJMP: /* normal sequence */ | |
81d3858d JR |
495 | /* Avoid problems if early cleanup() */ |
496 | fd_map = -1; | |
497 | ehdr_curr = NULL; | |
498 | mmap_failed = 1; | |
dfad3d59 | 499 | do_file(file); |
e90b0c8b SR |
500 | break; |
501 | case SJ_FAIL: /* error in do_file or below */ | |
81d3858d | 502 | ++n_error; |
e90b0c8b SR |
503 | break; |
504 | case SJ_SUCCEED: /* premature success */ | |
81d3858d | 505 | /* do nothing */ |
e90b0c8b | 506 | break; |
81d3858d JR |
507 | } /* end switch */ |
508 | } | |
509 | return !!n_error; | |
510 | } | |
511 | ||
512 |