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Source at commit 6c17a31f1fc515425221067cb3ece599c09dbc5d created 12 years 8 months ago. By Werner Almesberger, atusb, atben: moved from spi/ to ieee802154/; renamed atusb to spi_atusb | |
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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 | |
35 | static int fd_map; /* File descriptor for file being modified. */ |
36 | static int mmap_failed; /* Boolean flag. */ |
37 | static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */ |
38 | static char gpfx; /* prefix for global symbol name (sometimes '_') */ |
39 | static struct stat sb; /* Remember .st_size, etc. */ |
40 | static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */ |
41 | static const char *altmcount; /* alternate mcount symbol name */ |
42 | |
43 | /* setjmp() return values */ |
44 | enum { |
45 | SJ_SETJMP = 0, /* hardwired first return */ |
46 | SJ_FAIL, |
47 | SJ_SUCCEED |
48 | }; |
49 | |
50 | /* Per-file resource cleanup when multiple files. */ |
51 | static void |
52 | cleanup(void) |
53 | { |
54 | if (!mmap_failed) |
55 | munmap(ehdr_curr, sb.st_size); |
56 | else |
57 | free(ehdr_curr); |
58 | close(fd_map); |
59 | } |
60 | |
61 | static void __attribute__((noreturn)) |
62 | fail_file(void) |
63 | { |
64 | cleanup(); |
65 | longjmp(jmpenv, SJ_FAIL); |
66 | } |
67 | |
68 | static void __attribute__((noreturn)) |
69 | succeed_file(void) |
70 | { |
71 | cleanup(); |
72 | longjmp(jmpenv, SJ_SUCCEED); |
73 | } |
74 | |
75 | /* ulseek, uread, ...: Check return value for errors. */ |
76 | |
77 | static off_t |
78 | ulseek(int const fd, off_t const offset, int const whence) |
79 | { |
80 | off_t const w = lseek(fd, offset, whence); |
81 | if ((off_t)-1 == w) { |
82 | perror("lseek"); |
83 | fail_file(); |
84 | } |
85 | return w; |
86 | } |
87 | |
88 | static size_t |
89 | uread(int const fd, void *const buf, size_t const count) |
90 | { |
91 | size_t const n = read(fd, buf, count); |
92 | if (n != count) { |
93 | perror("read"); |
94 | fail_file(); |
95 | } |
96 | return n; |
97 | } |
98 | |
99 | static size_t |
100 | uwrite(int const fd, void const *const buf, size_t const count) |
101 | { |
102 | size_t const n = write(fd, buf, count); |
103 | if (n != count) { |
104 | perror("write"); |
105 | fail_file(); |
106 | } |
107 | return n; |
108 | } |
109 | |
110 | static void * |
111 | umalloc(size_t size) |
112 | { |
113 | void *const addr = malloc(size); |
114 | if (0 == addr) { |
115 | fprintf(stderr, "malloc failed: %zu bytes\n", size); |
116 | fail_file(); |
117 | } |
118 | return addr; |
119 | } |
120 | |
121 | /* |
122 | * Get the whole file as a programming convenience in order to avoid |
123 | * malloc+lseek+read+free of many pieces. If successful, then mmap |
124 | * avoids copying unused pieces; else just read the whole file. |
125 | * Open for both read and write; new info will be appended to the file. |
126 | * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr |
127 | * do not propagate to the file until an explicit overwrite at the last. |
128 | * This preserves most aspects of consistency (all except .st_size) |
129 | * for simultaneous readers of the file while we are appending to it. |
130 | * However, multiple writers still are bad. We choose not to use |
131 | * locking because it is expensive and the use case of kernel build |
132 | * makes multiple writers unlikely. |
133 | */ |
134 | static void *mmap_file(char const *fname) |
135 | { |
136 | void *addr; |
137 | |
138 | fd_map = open(fname, O_RDWR); |
139 | if (0 > fd_map || 0 > fstat(fd_map, &sb)) { |
140 | perror(fname); |
141 | fail_file(); |
142 | } |
143 | if (!S_ISREG(sb.st_mode)) { |
144 | fprintf(stderr, "not a regular file: %s\n", fname); |
145 | fail_file(); |
146 | } |
147 | addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, |
148 | fd_map, 0); |
149 | mmap_failed = 0; |
150 | if (MAP_FAILED == addr) { |
151 | mmap_failed = 1; |
152 | addr = umalloc(sb.st_size); |
153 | uread(fd_map, addr, sb.st_size); |
154 | } |
155 | return addr; |
156 | } |
157 | |
158 | /* w8rev, w8nat, ...: Handle endianness. */ |
159 | |
160 | static uint64_t w8rev(uint64_t const x) |
161 | { |
162 | return ((0xff & (x >> (0 * 8))) << (7 * 8)) |
163 | | ((0xff & (x >> (1 * 8))) << (6 * 8)) |
164 | | ((0xff & (x >> (2 * 8))) << (5 * 8)) |
165 | | ((0xff & (x >> (3 * 8))) << (4 * 8)) |
166 | | ((0xff & (x >> (4 * 8))) << (3 * 8)) |
167 | | ((0xff & (x >> (5 * 8))) << (2 * 8)) |
168 | | ((0xff & (x >> (6 * 8))) << (1 * 8)) |
169 | | ((0xff & (x >> (7 * 8))) << (0 * 8)); |
170 | } |
171 | |
172 | static uint32_t w4rev(uint32_t const x) |
173 | { |
174 | return ((0xff & (x >> (0 * 8))) << (3 * 8)) |
175 | | ((0xff & (x >> (1 * 8))) << (2 * 8)) |
176 | | ((0xff & (x >> (2 * 8))) << (1 * 8)) |
177 | | ((0xff & (x >> (3 * 8))) << (0 * 8)); |
178 | } |
179 | |
180 | static uint32_t w2rev(uint16_t const x) |
181 | { |
182 | return ((0xff & (x >> (0 * 8))) << (1 * 8)) |
183 | | ((0xff & (x >> (1 * 8))) << (0 * 8)); |
184 | } |
185 | |
186 | static uint64_t w8nat(uint64_t const x) |
187 | { |
188 | return x; |
189 | } |
190 | |
191 | static uint32_t w4nat(uint32_t const x) |
192 | { |
193 | return x; |
194 | } |
195 | |
196 | static uint32_t w2nat(uint16_t const x) |
197 | { |
198 | return x; |
199 | } |
200 | |
201 | static uint64_t (*w8)(uint64_t); |
202 | static uint32_t (*w)(uint32_t); |
203 | static uint32_t (*w2)(uint16_t); |
204 | |
205 | /* Names of the sections that could contain calls to mcount. */ |
206 | static int |
207 | is_mcounted_section_name(char const *const txtname) |
208 | { |
209 | return 0 == strcmp(".text", txtname) || |
210 | 0 == strcmp(".sched.text", txtname) || |
211 | 0 == strcmp(".spinlock.text", txtname) || |
212 | 0 == strcmp(".irqentry.text", txtname) || |
213 | 0 == strcmp(".text.unlikely", txtname); |
214 | } |
215 | |
216 | /* 32 bit and 64 bit are very similar */ |
217 | #include "recordmcount.h" |
218 | #define RECORD_MCOUNT_64 |
219 | #include "recordmcount.h" |
220 | |
221 | /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. |
222 | * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf |
223 | * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] |
224 | * to imply the order of the members; the spec does not say so. |
225 | * typedef unsigned char Elf64_Byte; |
226 | * fails on MIPS64 because their <elf.h> already has it! |
227 | */ |
228 | |
229 | typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */ |
230 | |
231 | union mips_r_info { |
232 | Elf64_Xword r_info; |
233 | struct { |
234 | Elf64_Word r_sym; /* Symbol index. */ |
235 | myElf64_Byte r_ssym; /* Special symbol. */ |
236 | myElf64_Byte r_type3; /* Third relocation. */ |
237 | myElf64_Byte r_type2; /* Second relocation. */ |
238 | myElf64_Byte r_type; /* First relocation. */ |
239 | } r_mips; |
240 | }; |
241 | |
242 | static uint64_t MIPS64_r_sym(Elf64_Rel const *rp) |
243 | { |
244 | return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym); |
245 | } |
246 | |
247 | static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type) |
248 | { |
249 | rp->r_info = ((union mips_r_info){ |
250 | .r_mips = { .r_sym = w(sym), .r_type = type } |
251 | }).r_info; |
252 | } |
253 | |
254 | static void |
255 | do_file(char const *const fname) |
256 | { |
257 | Elf32_Ehdr *const ehdr = mmap_file(fname); |
258 | unsigned int reltype = 0; |
259 | |
260 | ehdr_curr = ehdr; |
261 | w = w4nat; |
262 | w2 = w2nat; |
263 | w8 = w8nat; |
264 | switch (ehdr->e_ident[EI_DATA]) { |
265 | static unsigned int const endian = 1; |
266 | default: { |
267 | fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", |
268 | ehdr->e_ident[EI_DATA], fname); |
269 | fail_file(); |
270 | } break; |
271 | case ELFDATA2LSB: { |
272 | if (1 != *(unsigned char const *)&endian) { |
273 | /* main() is big endian, file.o is little endian. */ |
274 | w = w4rev; |
275 | w2 = w2rev; |
276 | w8 = w8rev; |
277 | } |
278 | } break; |
279 | case ELFDATA2MSB: { |
280 | if (0 != *(unsigned char const *)&endian) { |
281 | /* main() is little endian, file.o is big endian. */ |
282 | w = w4rev; |
283 | w2 = w2rev; |
284 | w8 = w8rev; |
285 | } |
286 | } break; |
287 | } /* end switch */ |
288 | if (0 != memcmp(ELFMAG, ehdr->e_ident, SELFMAG) |
289 | || ET_REL != w2(ehdr->e_type) |
290 | || EV_CURRENT != ehdr->e_ident[EI_VERSION]) { |
291 | fprintf(stderr, "unrecognized ET_REL file %s\n", fname); |
292 | fail_file(); |
293 | } |
294 | |
295 | gpfx = 0; |
296 | switch (w2(ehdr->e_machine)) { |
297 | default: { |
298 | fprintf(stderr, "unrecognized e_machine %d %s\n", |
299 | w2(ehdr->e_machine), fname); |
300 | fail_file(); |
301 | } break; |
302 | case EM_386: reltype = R_386_32; break; |
303 | case EM_ARM: reltype = R_ARM_ABS32; |
304 | altmcount = "__gnu_mcount_nc"; |
305 | break; |
306 | case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break; |
307 | case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break; |
308 | case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break; |
309 | case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break; |
310 | case EM_S390: /* reltype: e_class */ gpfx = '_'; break; |
311 | case EM_SH: reltype = R_SH_DIR32; break; |
312 | case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break; |
313 | case EM_X86_64: reltype = R_X86_64_64; break; |
314 | } /* end switch */ |
315 | |
316 | switch (ehdr->e_ident[EI_CLASS]) { |
317 | default: { |
318 | fprintf(stderr, "unrecognized ELF class %d %s\n", |
319 | ehdr->e_ident[EI_CLASS], fname); |
320 | fail_file(); |
321 | } break; |
322 | case ELFCLASS32: { |
323 | if (sizeof(Elf32_Ehdr) != w2(ehdr->e_ehsize) |
324 | || sizeof(Elf32_Shdr) != w2(ehdr->e_shentsize)) { |
325 | fprintf(stderr, |
326 | "unrecognized ET_REL file: %s\n", fname); |
327 | fail_file(); |
328 | } |
329 | if (EM_S390 == w2(ehdr->e_machine)) |
330 | reltype = R_390_32; |
331 | if (EM_MIPS == w2(ehdr->e_machine)) { |
332 | reltype = R_MIPS_32; |
333 | is_fake_mcount32 = MIPS32_is_fake_mcount; |
334 | } |
335 | do32(ehdr, fname, reltype); |
336 | } break; |
337 | case ELFCLASS64: { |
338 | Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr; |
339 | if (sizeof(Elf64_Ehdr) != w2(ghdr->e_ehsize) |
340 | || sizeof(Elf64_Shdr) != w2(ghdr->e_shentsize)) { |
341 | fprintf(stderr, |
342 | "unrecognized ET_REL file: %s\n", fname); |
343 | fail_file(); |
344 | } |
345 | if (EM_S390 == w2(ghdr->e_machine)) |
346 | reltype = R_390_64; |
347 | if (EM_MIPS == w2(ghdr->e_machine)) { |
348 | reltype = R_MIPS_64; |
349 | Elf64_r_sym = MIPS64_r_sym; |
350 | Elf64_r_info = MIPS64_r_info; |
351 | is_fake_mcount64 = MIPS64_is_fake_mcount; |
352 | } |
353 | do64(ghdr, fname, reltype); |
354 | } break; |
355 | } /* end switch */ |
356 | |
357 | cleanup(); |
358 | } |
359 | |
360 | int |
361 | main(int argc, char const *argv[]) |
362 | { |
363 | const char ftrace[] = "/ftrace.o"; |
364 | int ftrace_size = sizeof(ftrace) - 1; |
365 | int n_error = 0; /* gcc-4.3.0 false positive complaint */ |
366 | |
367 | if (argc <= 1) { |
368 | fprintf(stderr, "usage: recordmcount file.o...\n"); |
369 | return 0; |
370 | } |
371 | |
372 | /* Process each file in turn, allowing deep failure. */ |
373 | for (--argc, ++argv; 0 < argc; --argc, ++argv) { |
374 | int const sjval = setjmp(jmpenv); |
375 | int len; |
376 | |
377 | /* |
378 | * The file kernel/trace/ftrace.o references the mcount |
379 | * function but does not call it. Since ftrace.o should |
380 | * not be traced anyway, we just skip it. |
381 | */ |
382 | len = strlen(argv[0]); |
383 | if (len >= ftrace_size && |
384 | strcmp(argv[0] + (len - ftrace_size), ftrace) == 0) |
385 | continue; |
386 | |
387 | switch (sjval) { |
388 | default: { |
389 | fprintf(stderr, "internal error: %s\n", argv[0]); |
390 | exit(1); |
391 | } break; |
392 | case SJ_SETJMP: { /* normal sequence */ |
393 | /* Avoid problems if early cleanup() */ |
394 | fd_map = -1; |
395 | ehdr_curr = NULL; |
396 | mmap_failed = 1; |
397 | do_file(argv[0]); |
398 | } break; |
399 | case SJ_FAIL: { /* error in do_file or below */ |
400 | ++n_error; |
401 | } break; |
402 | case SJ_SUCCEED: { /* premature success */ |
403 | /* do nothing */ |
404 | } break; |
405 | } /* end switch */ |
406 | } |
407 | return !!n_error; |
408 | } |
409 | |
410 | |
411 |
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