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new x86 CPU core
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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;
201 /* find ret */
202 while (p > p_start && *p != 0xc3)
203 p--;
204 /* skip double ret */
205 if (p > p_start && p[-1] == 0xc3)
206 p--;
207 if (p == p_start)
208 error("empty code for %s", name);
209 copy_size = p - p_start;
210 }
211 break;
212 case EM_PPC:
213 {
214 uint8_t *p;
215 p = (void *)(p_end - 4);
216 /* find ret */
217 while (p > p_start && get32((uint32_t *)p) != 0x4e800020)
218 p -= 4;
219 /* skip double ret */
220 if (p > p_start && get32((uint32_t *)(p - 4)) == 0x4e800020)
221 p -= 4;
222 if (p == p_start)
223 error("empty code for %s", name);
224 copy_size = p - p_start;
225 }
226 break;
227 default:
228 error("unsupported CPU (%d)", e_machine);
229 }
230
231 /* compute the number of arguments by looking at the relocations */
232 for(i = 0;i < MAX_ARGS; i++)
233 args_present[i] = 0;
234
235 if (reloc_sh_type == SHT_REL) {
236 Elf32_Rel *rel;
237 int n;
238 for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
239 if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) {
240 sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name;
241 if (strstart(sym_name, "__op_param", &p)) {
242 n = strtoul(p, NULL, 10);
243 if (n >= MAX_ARGS)
244 error("too many arguments in %s", name);
245 args_present[n - 1] = 1;
246 }
247 }
248 }
249 } else {
250 Elf32_Rela *rel;
251 int n;
252 for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
253 if (rel->r_offset >= offset && rel->r_offset < offset + copy_size) {
254 sym_name = strtab + symtab[ELF32_R_SYM(rel->r_info)].st_name;
255 if (strstart(sym_name, "__op_param", &p)) {
256 n = strtoul(p, NULL, 10);
257 if (n >= MAX_ARGS)
258 error("too many arguments in %s", name);
259 args_present[n - 1] = 1;
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 }