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367e86e8 FB |
1 | #include <stdlib.h> |
2 | #include <stdio.h> | |
3 | #include <stdarg.h> | |
4 | #include <inttypes.h> | |
5 | #include <elf.h> | |
6 | #include <unistd.h> | |
7 | #include <fcntl.h> | |
8 | ||
9 | #include "thunk.h" | |
10 | ||
11 | /* all dynamically generated functions begin with this code */ | |
12 | #define OP_PREFIX "op" | |
13 | ||
14 | int elf_must_swap(Elf32_Ehdr *h) | |
15 | { | |
16 | union { | |
17 | uint32_t i; | |
18 | uint8_t b[4]; | |
19 | } swaptest; | |
20 | ||
21 | swaptest.i = 1; | |
22 | return (h->e_ident[EI_DATA] == ELFDATA2MSB) != | |
23 | (swaptest.b[0] == 0); | |
24 | } | |
25 | ||
26 | void swab16s(uint16_t *p) | |
27 | { | |
28 | *p = bswap16(*p); | |
29 | } | |
30 | ||
31 | void swab32s(uint32_t *p) | |
32 | { | |
33 | *p = bswap32(*p); | |
34 | } | |
35 | ||
36 | void swab64s(uint32_t *p) | |
37 | { | |
38 | *p = bswap64(*p); | |
39 | } | |
40 | ||
41 | void elf_swap_ehdr(Elf32_Ehdr *h) | |
42 | { | |
43 | swab16s(&h->e_type); /* Object file type */ | |
44 | swab16s(&h-> e_machine); /* Architecture */ | |
45 | swab32s(&h-> e_version); /* Object file version */ | |
46 | swab32s(&h-> e_entry); /* Entry point virtual address */ | |
47 | swab32s(&h-> e_phoff); /* Program header table file offset */ | |
48 | swab32s(&h-> e_shoff); /* Section header table file offset */ | |
49 | swab32s(&h-> e_flags); /* Processor-specific flags */ | |
50 | swab16s(&h-> e_ehsize); /* ELF header size in bytes */ | |
51 | swab16s(&h-> e_phentsize); /* Program header table entry size */ | |
52 | swab16s(&h-> e_phnum); /* Program header table entry count */ | |
53 | swab16s(&h-> e_shentsize); /* Section header table entry size */ | |
54 | swab16s(&h-> e_shnum); /* Section header table entry count */ | |
55 | swab16s(&h-> e_shstrndx); /* Section header string table index */ | |
56 | } | |
57 | ||
58 | void elf_swap_shdr(Elf32_Shdr *h) | |
59 | { | |
60 | swab32s(&h-> sh_name); /* Section name (string tbl index) */ | |
61 | swab32s(&h-> sh_type); /* Section type */ | |
62 | swab32s(&h-> sh_flags); /* Section flags */ | |
63 | swab32s(&h-> sh_addr); /* Section virtual addr at execution */ | |
64 | swab32s(&h-> sh_offset); /* Section file offset */ | |
65 | swab32s(&h-> sh_size); /* Section size in bytes */ | |
66 | swab32s(&h-> sh_link); /* Link to another section */ | |
67 | swab32s(&h-> sh_info); /* Additional section information */ | |
68 | swab32s(&h-> sh_addralign); /* Section alignment */ | |
69 | swab32s(&h-> sh_entsize); /* Entry size if section holds table */ | |
70 | } | |
71 | ||
72 | void elf_swap_phdr(Elf32_Phdr *h) | |
73 | { | |
74 | swab32s(&h->p_type); /* Segment type */ | |
75 | swab32s(&h->p_offset); /* Segment file offset */ | |
76 | swab32s(&h->p_vaddr); /* Segment virtual address */ | |
77 | swab32s(&h->p_paddr); /* Segment physical address */ | |
78 | swab32s(&h->p_filesz); /* Segment size in file */ | |
79 | swab32s(&h->p_memsz); /* Segment size in memory */ | |
80 | swab32s(&h->p_flags); /* Segment flags */ | |
81 | swab32s(&h->p_align); /* Segment alignment */ | |
82 | } | |
83 | ||
84 | int do_swap; | |
85 | int e_machine; | |
86 | ||
87 | uint16_t get16(uint16_t *p) | |
88 | { | |
89 | uint16_t val; | |
90 | val = *p; | |
91 | if (do_swap) | |
92 | val = bswap16(val); | |
93 | return val; | |
94 | } | |
95 | ||
96 | uint32_t get32(uint32_t *p) | |
97 | { | |
98 | uint32_t val; | |
99 | val = *p; | |
100 | if (do_swap) | |
101 | val = bswap32(val); | |
102 | return val; | |
103 | } | |
104 | ||
105 | void put16(uint16_t *p, uint16_t val) | |
106 | { | |
107 | if (do_swap) | |
108 | val = bswap16(val); | |
109 | *p = val; | |
110 | } | |
111 | ||
112 | void put32(uint32_t *p, uint32_t val) | |
113 | { | |
114 | if (do_swap) | |
115 | val = bswap32(val); | |
116 | *p = val; | |
117 | } | |
118 | ||
119 | void __attribute__((noreturn)) error(const char *fmt, ...) | |
120 | { | |
121 | va_list ap; | |
122 | va_start(ap, fmt); | |
123 | fprintf(stderr, "dyngen: "); | |
124 | vfprintf(stderr, fmt, ap); | |
125 | fprintf(stderr, "\n"); | |
126 | va_end(ap); | |
127 | exit(1); | |
128 | } | |
129 | ||
130 | ||
131 | Elf32_Shdr *find_elf_section(Elf32_Shdr *shdr, int shnum, const char *shstr, | |
132 | const char *name) | |
133 | { | |
134 | int i; | |
135 | const char *shname; | |
136 | Elf32_Shdr *sec; | |
137 | ||
138 | for(i = 0; i < shnum; i++) { | |
139 | sec = &shdr[i]; | |
140 | if (!sec->sh_name) | |
141 | continue; | |
142 | shname = shstr + sec->sh_name; | |
143 | if (!strcmp(shname, name)) | |
144 | return sec; | |
145 | } | |
146 | return NULL; | |
147 | } | |
148 | ||
149 | void *load_data(int fd, long offset, unsigned int size) | |
150 | { | |
151 | char *data; | |
152 | ||
153 | data = malloc(size); | |
154 | if (!data) | |
155 | return NULL; | |
156 | lseek(fd, offset, SEEK_SET); | |
157 | if (read(fd, data, size) != size) { | |
158 | free(data); | |
159 | return NULL; | |
160 | } | |
161 | return data; | |
162 | } | |
163 | ||
164 | int strstart(const char *str, const char *val, const char **ptr) | |
165 | { | |
166 | const char *p, *q; | |
167 | p = str; | |
168 | q = val; | |
169 | while (*q != '\0') { | |
170 | if (*p != *q) | |
171 | return 0; | |
172 | p++; | |
173 | q++; | |
174 | } | |
175 | if (ptr) | |
176 | *ptr = p; | |
177 | return 1; | |
178 | } | |
179 | ||
180 | #define MAX_ARGS 3 | |
181 | ||
182 | /* generate op code */ | |
183 | void gen_code(const char *name, unsigned long offset, unsigned long size, | |
184 | FILE *outfile, uint8_t *text, void *relocs, int nb_relocs, int reloc_sh_type, | |
185 | Elf32_Sym *symtab, char *strtab) | |
186 | { | |
187 | int copy_size = 0; | |
188 | uint8_t *p_start, *p_end; | |
189 | int nb_args, i; | |
190 | uint8_t args_present[MAX_ARGS]; | |
191 | const char *sym_name, *p; | |
192 | ||
193 | /* compute exact size excluding return instruction */ | |
194 | p_start = text + offset; | |
195 | p_end = p_start + size; | |
196 | switch(e_machine) { | |
197 | case EM_386: | |
198 | { | |
199 | uint8_t *p; | |
200 | p = p_end - 1; | |
367e86e8 FB |
201 | if (p == p_start) |
202 | error("empty code for %s", name); | |
4b74fe1f FB |
203 | if (p[0] != 0xc3) |
204 | error("ret expected at the end of %s", name); | |
367e86e8 FB |
205 | copy_size = p - p_start; |
206 | } | |
207 | break; | |
208 | case EM_PPC: | |
209 | { | |
210 | uint8_t *p; | |
211 | p = (void *)(p_end - 4); | |
212 | /* find ret */ | |
213 | while (p > p_start && get32((uint32_t *)p) != 0x4e800020) | |
214 | p -= 4; | |
215 | /* skip double ret */ | |
216 | if (p > p_start && get32((uint32_t *)(p - 4)) == 0x4e800020) | |
217 | p -= 4; | |
218 | if (p == p_start) | |
219 | error("empty code for %s", name); | |
220 | copy_size = p - p_start; | |
221 | } | |
222 | break; | |
223 | default: | |
224 | error("unsupported CPU (%d)", e_machine); | |
225 | } | |
226 | ||
227 | /* compute the number of arguments by looking at the relocations */ | |
228 | for(i = 0;i < MAX_ARGS; i++) | |
229 | args_present[i] = 0; | |
230 | ||
231 | if (reloc_sh_type == SHT_REL) { | |
232 | Elf32_Rel *rel; | |
233 | int n; | |
234 | for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { | |
235 | if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { | |
236 | sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; | |
237 | if (strstart(sym_name, "__op_param", &p)) { | |
238 | n = strtoul(p, NULL, 10); | |
239 | if (n >= MAX_ARGS) | |
240 | error("too many arguments in %s", name); | |
241 | args_present[n - 1] = 1; | |
927f621e FB |
242 | } else { |
243 | fprintf(outfile, "extern char %s;\n", sym_name); | |
367e86e8 FB |
244 | } |
245 | } | |
246 | } | |
247 | } else { | |
248 | Elf32_Rela *rel; | |
249 | int n; | |
250 | for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { | |
251 | if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { | |
252 | sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; | |
253 | if (strstart(sym_name, "__op_param", &p)) { | |
254 | n = strtoul(p, NULL, 10); | |
255 | if (n >= MAX_ARGS) | |
256 | error("too many arguments in %s", name); | |
257 | args_present[n - 1] = 1; | |
927f621e FB |
258 | } else { |
259 | fprintf(outfile, "extern char %s;\n", sym_name); | |
367e86e8 FB |
260 | } |
261 | } | |
262 | } | |
263 | } | |
264 | ||
265 | nb_args = 0; | |
266 | while (nb_args < MAX_ARGS && args_present[nb_args]) | |
267 | nb_args++; | |
268 | for(i = nb_args; i < MAX_ARGS; i++) { | |
269 | if (args_present[i]) | |
270 | error("inconsistent argument numbering in %s", name); | |
271 | } | |
272 | ||
273 | /* output C code */ | |
274 | fprintf(outfile, "extern void %s();\n", name); | |
275 | fprintf(outfile, "static inline void gen_%s(", name); | |
276 | if (nb_args == 0) { | |
277 | fprintf(outfile, "void"); | |
278 | } else { | |
279 | for(i = 0; i < nb_args; i++) { | |
280 | if (i != 0) | |
281 | fprintf(outfile, ", "); | |
282 | fprintf(outfile, "long param%d", i + 1); | |
283 | } | |
284 | } | |
285 | fprintf(outfile, ")\n"); | |
286 | fprintf(outfile, "{\n"); | |
287 | fprintf(outfile, " memcpy(gen_code_ptr, &%s, %d);\n", name, copy_size); | |
288 | ||
289 | /* patch relocations */ | |
290 | switch(e_machine) { | |
291 | case EM_386: | |
292 | { | |
293 | Elf32_Rel *rel; | |
294 | char name[256]; | |
295 | int type; | |
296 | long addend; | |
297 | for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) { | |
298 | if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) { | |
299 | sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name; | |
300 | if (strstart(sym_name, "__op_param", &p)) { | |
301 | snprintf(name, sizeof(name), "param%s", p); | |
302 | } else { | |
303 | snprintf(name, sizeof(name), "(long)(&%s)", sym_name); | |
304 | } | |
305 | type = ELF32_R_TYPE(rel->r_info); | |
306 | addend = get32((uint32_t *)(text + rel->r_offset)); | |
307 | switch(type) { | |
308 | case R_386_32: | |
309 | fprintf(outfile, " *(uint32_t *)(gen_code_ptr + %ld) = %s + %ld;\n", | |
310 | rel->r_offset - offset, name, addend); | |
311 | break; | |
312 | case R_386_PC32: | |
313 | fprintf(outfile, " *(uint32_t *)(gen_code_ptr + %ld) = %s - (long)(gen_code_ptr + %ld) + %ld;\n", | |
314 | rel->r_offset - offset, name, rel->r_offset - offset, addend); | |
315 | break; | |
316 | default: | |
317 | error("unsupported i386 relocation (%d)", type); | |
318 | } | |
319 | } | |
320 | } | |
321 | } | |
322 | break; | |
323 | default: | |
324 | error("unsupported CPU for relocations (%d)", e_machine); | |
325 | } | |
326 | ||
327 | ||
328 | fprintf(outfile, " gen_code_ptr += %d;\n", copy_size); | |
329 | fprintf(outfile, "}\n\n"); | |
330 | } | |
331 | ||
332 | /* load an elf object file */ | |
333 | int load_elf(const char *filename, FILE *outfile) | |
334 | { | |
335 | int fd; | |
336 | Elf32_Ehdr ehdr; | |
337 | Elf32_Shdr *sec, *shdr, *symtab_sec, *strtab_sec, *text_sec; | |
338 | int i, j, nb_syms; | |
339 | Elf32_Sym *symtab, *sym; | |
340 | const char *cpu_name; | |
341 | char *shstr, *strtab; | |
342 | uint8_t *text; | |
343 | void *relocs; | |
344 | int nb_relocs, reloc_sh_type; | |
345 | ||
346 | fd = open(filename, O_RDONLY); | |
347 | if (fd < 0) | |
348 | error("can't open file '%s'", filename); | |
349 | ||
350 | /* Read ELF header. */ | |
351 | if (read(fd, &ehdr, sizeof (ehdr)) != sizeof (ehdr)) | |
352 | error("unable to read file header"); | |
353 | ||
354 | /* Check ELF identification. */ | |
355 | if (ehdr.e_ident[EI_MAG0] != ELFMAG0 | |
356 | || ehdr.e_ident[EI_MAG1] != ELFMAG1 | |
357 | || ehdr.e_ident[EI_MAG2] != ELFMAG2 | |
358 | || ehdr.e_ident[EI_MAG3] != ELFMAG3 | |
359 | || ehdr.e_ident[EI_CLASS] != ELFCLASS32 | |
360 | || ehdr.e_ident[EI_VERSION] != EV_CURRENT) { | |
361 | error("bad ELF header"); | |
362 | } | |
363 | ||
364 | do_swap = elf_must_swap(&ehdr); | |
365 | if (do_swap) | |
366 | elf_swap_ehdr(&ehdr); | |
367 | if (ehdr.e_type != ET_REL) | |
368 | error("ELF object file expected"); | |
369 | if (ehdr.e_version != EV_CURRENT) | |
370 | error("Invalid ELF version"); | |
371 | e_machine = ehdr.e_machine; | |
372 | ||
373 | /* read section headers */ | |
374 | shdr = load_data(fd, ehdr.e_shoff, ehdr.e_shnum * sizeof(Elf32_Shdr)); | |
375 | if (do_swap) { | |
376 | for(i = 0; i < ehdr.e_shnum; i++) { | |
377 | elf_swap_shdr(&shdr[i]); | |
378 | } | |
379 | } | |
380 | ||
381 | sec = &shdr[ehdr.e_shstrndx]; | |
382 | shstr = load_data(fd, sec->sh_offset, sec->sh_size); | |
383 | ||
384 | /* text section */ | |
385 | ||
386 | text_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".text"); | |
387 | if (!text_sec) | |
388 | error("could not find .text section"); | |
389 | text = load_data(fd, text_sec->sh_offset, text_sec->sh_size); | |
390 | ||
391 | /* find text relocations, if any */ | |
392 | nb_relocs = 0; | |
393 | relocs = NULL; | |
394 | reloc_sh_type = 0; | |
395 | for(i = 0; i < ehdr.e_shnum; i++) { | |
396 | sec = &shdr[i]; | |
397 | if ((sec->sh_type == SHT_REL || sec->sh_type == SHT_RELA) && | |
398 | sec->sh_info == (text_sec - shdr)) { | |
399 | reloc_sh_type = sec->sh_type; | |
400 | relocs = load_data(fd, sec->sh_offset, sec->sh_size); | |
401 | nb_relocs = sec->sh_size / sec->sh_entsize; | |
402 | if (do_swap) { | |
403 | if (sec->sh_type == SHT_REL) { | |
404 | Elf32_Rel *rel = relocs; | |
405 | for(j = 0, rel = relocs; j < nb_relocs; j++, rel++) { | |
406 | swab32s(&rel->r_offset); | |
407 | swab32s(&rel->r_info); | |
408 | } | |
409 | } else { | |
410 | Elf32_Rela *rel = relocs; | |
411 | for(j = 0, rel = relocs; j < nb_relocs; j++, rel++) { | |
412 | swab32s(&rel->r_offset); | |
413 | swab32s(&rel->r_info); | |
414 | swab32s(&rel->r_addend); | |
415 | } | |
416 | } | |
417 | } | |
418 | break; | |
419 | } | |
420 | } | |
421 | ||
422 | symtab_sec = find_elf_section(shdr, ehdr.e_shnum, shstr, ".symtab"); | |
423 | if (!symtab_sec) | |
424 | error("could not find .symtab section"); | |
425 | strtab_sec = &shdr[symtab_sec->sh_link]; | |
426 | ||
427 | symtab = load_data(fd, symtab_sec->sh_offset, symtab_sec->sh_size); | |
428 | strtab = load_data(fd, strtab_sec->sh_offset, strtab_sec->sh_size); | |
429 | ||
430 | nb_syms = symtab_sec->sh_size / sizeof(Elf32_Sym); | |
431 | if (do_swap) { | |
432 | for(i = 0, sym = symtab; i < nb_syms; i++, sym++) { | |
433 | swab32s(&sym->st_name); | |
434 | swab32s(&sym->st_value); | |
435 | swab32s(&sym->st_size); | |
436 | swab16s(&sym->st_shndx); | |
437 | } | |
438 | } | |
439 | ||
440 | switch(e_machine) { | |
441 | case EM_386: | |
442 | cpu_name = "i386"; | |
443 | break; | |
444 | case EM_PPC: | |
445 | cpu_name = "ppc"; | |
446 | break; | |
447 | case EM_MIPS: | |
448 | cpu_name = "mips"; | |
449 | break; | |
450 | case EM_ARM: | |
451 | cpu_name = "arm"; | |
452 | break; | |
453 | case EM_SPARC: | |
454 | cpu_name = "sparc"; | |
455 | break; | |
456 | default: | |
457 | error("unsupported CPU (e_machine=%d)", e_machine); | |
458 | } | |
459 | ||
460 | fprintf(outfile, "#include \"gen-%s.h\"\n\n", cpu_name); | |
461 | ||
462 | for(i = 0, sym = symtab; i < nb_syms; i++, sym++) { | |
463 | const char *name; | |
464 | name = strtab + sym->st_name; | |
465 | if (strstart(name, "op_", NULL) || | |
466 | strstart(name, "op1_", NULL) || | |
467 | strstart(name, "op2_", NULL) || | |
468 | strstart(name, "op3_", NULL)) { | |
469 | #if 0 | |
470 | printf("%4d: %s pos=0x%08x len=%d\n", | |
471 | i, name, sym->st_value, sym->st_size); | |
472 | #endif | |
473 | if (sym->st_shndx != (text_sec - shdr)) | |
474 | error("invalid section for opcode (0x%x)", sym->st_shndx); | |
475 | gen_code(name, sym->st_value, sym->st_size, outfile, | |
476 | text, relocs, nb_relocs, reloc_sh_type, symtab, strtab); | |
477 | } | |
478 | } | |
479 | ||
480 | close(fd); | |
481 | return 0; | |
482 | } | |
483 | ||
484 | void usage(void) | |
485 | { | |
486 | printf("dyngen (c) 2003 Fabrice Bellard\n" | |
487 | "usage: dyngen [-o outfile] objfile\n" | |
488 | "Generate a dynamic code generator from an object file\n"); | |
489 | exit(1); | |
490 | } | |
491 | ||
492 | int main(int argc, char **argv) | |
493 | { | |
494 | int c; | |
495 | const char *filename, *outfilename; | |
496 | FILE *outfile; | |
497 | ||
498 | outfilename = "out.c"; | |
499 | for(;;) { | |
500 | c = getopt(argc, argv, "ho:"); | |
501 | if (c == -1) | |
502 | break; | |
503 | switch(c) { | |
504 | case 'h': | |
505 | usage(); | |
506 | break; | |
507 | case 'o': | |
508 | outfilename = optarg; | |
509 | break; | |
510 | } | |
511 | } | |
512 | if (optind >= argc) | |
513 | usage(); | |
514 | filename = argv[optind]; | |
515 | outfile = fopen(outfilename, "w"); | |
516 | if (!outfile) | |
517 | error("could not open '%s'", outfilename); | |
518 | load_elf(filename, outfile); | |
519 | fclose(outfile); | |
520 | return 0; | |
521 | } |