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bd5635a1 RP |
1 | /* Intel 386 stuff. |
2 | Copyright (C) 1988, 1989 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | GDB is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GDB is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GDB; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | #include <stdio.h> | |
21 | #include "defs.h" | |
22 | #include "param.h" | |
23 | #include "frame.h" | |
24 | #include "inferior.h" | |
25 | #include "gdbcore.h" | |
26 | ||
27 | #ifdef USG | |
28 | #include <sys/types.h> | |
29 | #endif | |
30 | ||
31 | #include <sys/param.h> | |
32 | #include <sys/dir.h> | |
33 | #include <signal.h> | |
34 | #include <sys/user.h> | |
35 | #include <sys/ioctl.h> | |
36 | #include <fcntl.h> | |
37 | ||
38 | #ifndef N_SET_MAGIC | |
39 | #ifdef COFF_FORMAT | |
40 | #define N_SET_MAGIC(exec, val) ((exec).magic = (val)) | |
41 | #else | |
42 | #define N_SET_MAGIC(exec, val) ((exec).a_magic = (val)) | |
43 | #endif | |
44 | #endif | |
45 | ||
46 | #include <sys/file.h> | |
47 | #include <sys/stat.h> | |
48 | ||
49 | /* I don't know whether this is right for cross-debugging even if you | |
50 | do somehow manage to get the right include file. */ | |
51 | #if defined (USE_MACHINE_REG_H) | |
52 | #include <machine/reg.h> | |
53 | #else | |
54 | #include <sys/reg.h> | |
55 | #endif | |
56 | ||
57 | /* helper functions for m-i386.h */ | |
58 | ||
59 | /* stdio style buffering to minimize calls to ptrace */ | |
60 | static CORE_ADDR codestream_next_addr; | |
61 | static CORE_ADDR codestream_addr; | |
62 | static unsigned char codestream_buf[sizeof (int)]; | |
63 | static int codestream_off; | |
64 | static int codestream_cnt; | |
65 | ||
66 | #define codestream_tell() (codestream_addr + codestream_off) | |
67 | #define codestream_peek() (codestream_cnt == 0 ? \ | |
68 | codestream_fill(1): codestream_buf[codestream_off]) | |
69 | #define codestream_get() (codestream_cnt-- == 0 ? \ | |
70 | codestream_fill(0) : codestream_buf[codestream_off++]) | |
71 | ||
72 | static unsigned char | |
73 | codestream_fill (peek_flag) | |
74 | { | |
75 | codestream_addr = codestream_next_addr; | |
76 | codestream_next_addr += sizeof (int); | |
77 | codestream_off = 0; | |
78 | codestream_cnt = sizeof (int); | |
79 | read_memory (codestream_addr, | |
80 | (unsigned char *)codestream_buf, | |
81 | sizeof (int)); | |
82 | ||
83 | if (peek_flag) | |
84 | return (codestream_peek()); | |
85 | else | |
86 | return (codestream_get()); | |
87 | } | |
88 | ||
89 | static void | |
90 | codestream_seek (place) | |
91 | { | |
92 | codestream_next_addr = place & -sizeof (int); | |
93 | codestream_cnt = 0; | |
94 | codestream_fill (1); | |
95 | while (codestream_tell() != place) | |
96 | codestream_get (); | |
97 | } | |
98 | ||
99 | static void | |
100 | codestream_read (buf, count) | |
101 | unsigned char *buf; | |
102 | { | |
103 | unsigned char *p; | |
104 | int i; | |
105 | p = buf; | |
106 | for (i = 0; i < count; i++) | |
107 | *p++ = codestream_get (); | |
108 | } | |
109 | ||
110 | /* next instruction is a jump, move to target */ | |
111 | static | |
112 | i386_follow_jump () | |
113 | { | |
114 | int long_delta; | |
115 | short short_delta; | |
116 | char byte_delta; | |
117 | int data16; | |
118 | int pos; | |
119 | ||
120 | pos = codestream_tell (); | |
121 | ||
122 | data16 = 0; | |
123 | if (codestream_peek () == 0x66) | |
124 | { | |
125 | codestream_get (); | |
126 | data16 = 1; | |
127 | } | |
128 | ||
129 | switch (codestream_get ()) | |
130 | { | |
131 | case 0xe9: | |
132 | /* relative jump: if data16 == 0, disp32, else disp16 */ | |
133 | if (data16) | |
134 | { | |
135 | codestream_read ((unsigned char *)&short_delta, 2); | |
136 | pos += short_delta + 3; /* include size of jmp inst */ | |
137 | } | |
138 | else | |
139 | { | |
140 | codestream_read ((unsigned char *)&long_delta, 4); | |
141 | pos += long_delta + 5; | |
142 | } | |
143 | break; | |
144 | case 0xeb: | |
145 | /* relative jump, disp8 (ignore data16) */ | |
146 | codestream_read ((unsigned char *)&byte_delta, 1); | |
147 | pos += byte_delta + 2; | |
148 | break; | |
149 | } | |
150 | codestream_seek (pos + data16); | |
151 | } | |
152 | ||
153 | /* | |
154 | * find & return amound a local space allocated, and advance codestream to | |
155 | * first register push (if any) | |
156 | * | |
157 | * if entry sequence doesn't make sense, return -1, and leave | |
158 | * codestream pointer random | |
159 | */ | |
160 | static long | |
161 | i386_get_frame_setup (pc) | |
162 | { | |
163 | unsigned char op; | |
164 | ||
165 | codestream_seek (pc); | |
166 | ||
167 | i386_follow_jump (); | |
168 | ||
169 | op = codestream_get (); | |
170 | ||
171 | if (op == 0x58) /* popl %eax */ | |
172 | { | |
173 | /* | |
174 | * this function must start with | |
175 | * | |
176 | * popl %eax 0x58 | |
177 | * xchgl %eax, (%esp) 0x87 0x04 0x24 | |
178 | * or xchgl %eax, 0(%esp) 0x87 0x44 0x24 0x00 | |
179 | * | |
180 | * (the system 5 compiler puts out the second xchg | |
181 | * inst, and the assembler doesn't try to optimize it, | |
182 | * so the 'sib' form gets generated) | |
183 | * | |
184 | * this sequence is used to get the address of the return | |
185 | * buffer for a function that returns a structure | |
186 | */ | |
187 | int pos; | |
188 | unsigned char buf[4]; | |
189 | static unsigned char proto1[3] = { 0x87,0x04,0x24 }; | |
190 | static unsigned char proto2[4] = { 0x87,0x44,0x24,0x00 }; | |
191 | pos = codestream_tell (); | |
192 | codestream_read (buf, 4); | |
193 | if (bcmp (buf, proto1, 3) == 0) | |
194 | pos += 3; | |
195 | else if (bcmp (buf, proto2, 4) == 0) | |
196 | pos += 4; | |
197 | ||
198 | codestream_seek (pos); | |
199 | op = codestream_get (); /* update next opcode */ | |
200 | } | |
201 | ||
202 | if (op == 0x55) /* pushl %ebp */ | |
203 | { | |
204 | /* check for movl %esp, %ebp - can be written two ways */ | |
205 | switch (codestream_get ()) | |
206 | { | |
207 | case 0x8b: | |
208 | if (codestream_get () != 0xec) | |
209 | return (-1); | |
210 | break; | |
211 | case 0x89: | |
212 | if (codestream_get () != 0xe5) | |
213 | return (-1); | |
214 | break; | |
215 | default: | |
216 | return (-1); | |
217 | } | |
218 | /* check for stack adjustment | |
219 | * | |
220 | * subl $XXX, %esp | |
221 | * | |
222 | * note: you can't subtract a 16 bit immediate | |
223 | * from a 32 bit reg, so we don't have to worry | |
224 | * about a data16 prefix | |
225 | */ | |
226 | op = codestream_peek (); | |
227 | if (op == 0x83) | |
228 | { | |
229 | /* subl with 8 bit immed */ | |
230 | codestream_get (); | |
231 | if (codestream_get () != 0xec) | |
232 | /* Some instruction starting with 0x83 other than subl. */ | |
233 | { | |
234 | codestream_seek (codestream_tell () - 2); | |
235 | return 0; | |
236 | } | |
237 | /* subl with signed byte immediate | |
238 | * (though it wouldn't make sense to be negative) | |
239 | */ | |
240 | return (codestream_get()); | |
241 | } | |
242 | else if (op == 0x81) | |
243 | { | |
244 | /* subl with 32 bit immed */ | |
245 | int locals; | |
246 | codestream_get(); | |
247 | if (codestream_get () != 0xec) | |
248 | /* Some instruction starting with 0x81 other than subl. */ | |
249 | { | |
250 | codestream_seek (codestream_tell () - 2); | |
251 | return 0; | |
252 | } | |
253 | /* subl with 32 bit immediate */ | |
254 | codestream_read ((unsigned char *)&locals, 4); | |
255 | return (locals); | |
256 | } | |
257 | else | |
258 | { | |
259 | return (0); | |
260 | } | |
261 | } | |
262 | else if (op == 0xc8) | |
263 | { | |
264 | /* enter instruction: arg is 16 bit unsigned immed */ | |
265 | unsigned short slocals; | |
266 | codestream_read ((unsigned char *)&slocals, 2); | |
267 | codestream_get (); /* flush final byte of enter instruction */ | |
268 | return (slocals); | |
269 | } | |
270 | return (-1); | |
271 | } | |
272 | ||
273 | /* Return number of args passed to a frame. | |
274 | Can return -1, meaning no way to tell. */ | |
275 | ||
276 | /* on the 386, the instruction following the call could be: | |
277 | * popl %ecx - one arg | |
278 | * addl $imm, %esp - imm/4 args; imm may be 8 or 32 bits | |
279 | * anything else - zero args | |
280 | */ | |
281 | ||
282 | int | |
283 | i386_frame_num_args (fi) | |
284 | struct frame_info fi; | |
285 | { | |
286 | int retpc; | |
287 | unsigned char op; | |
288 | struct frame_info *pfi; | |
289 | ||
290 | int frameless; | |
291 | ||
292 | FRAMELESS_FUNCTION_INVOCATION (fi, frameless); | |
293 | if (frameless) | |
294 | /* In the absence of a frame pointer, GDB doesn't get correct values | |
295 | for nameless arguments. Return -1, so it doesn't print any | |
296 | nameless arguments. */ | |
297 | return -1; | |
298 | ||
299 | pfi = get_prev_frame_info ((fi)); | |
300 | if (pfi == 0) | |
301 | { | |
302 | /* Note: this can happen if we are looking at the frame for | |
303 | main, because FRAME_CHAIN_VALID won't let us go into | |
304 | start. If we have debugging symbols, that's not really | |
305 | a big deal; it just means it will only show as many arguments | |
306 | to main as are declared. */ | |
307 | return -1; | |
308 | } | |
309 | else | |
310 | { | |
311 | retpc = pfi->pc; | |
312 | op = read_memory_integer (retpc, 1); | |
313 | if (op == 0x59) | |
314 | /* pop %ecx */ | |
315 | return 1; | |
316 | else if (op == 0x83) | |
317 | { | |
318 | op = read_memory_integer (retpc+1, 1); | |
319 | if (op == 0xc4) | |
320 | /* addl $<signed imm 8 bits>, %esp */ | |
321 | return (read_memory_integer (retpc+2,1)&0xff)/4; | |
322 | else | |
323 | return 0; | |
324 | } | |
325 | else if (op == 0x81) | |
326 | { /* add with 32 bit immediate */ | |
327 | op = read_memory_integer (retpc+1, 1); | |
328 | if (op == 0xc4) | |
329 | /* addl $<imm 32>, %esp */ | |
330 | return read_memory_integer (retpc+2, 4) / 4; | |
331 | else | |
332 | return 0; | |
333 | } | |
334 | else | |
335 | { | |
336 | return 0; | |
337 | } | |
338 | } | |
339 | } | |
340 | ||
341 | /* | |
342 | * parse the first few instructions of the function to see | |
343 | * what registers were stored. | |
344 | * | |
345 | * We handle these cases: | |
346 | * | |
347 | * The startup sequence can be at the start of the function, | |
348 | * or the function can start with a branch to startup code at the end. | |
349 | * | |
350 | * %ebp can be set up with either the 'enter' instruction, or | |
351 | * 'pushl %ebp, movl %esp, %ebp' (enter is too slow to be useful, | |
352 | * but was once used in the sys5 compiler) | |
353 | * | |
354 | * Local space is allocated just below the saved %ebp by either the | |
355 | * 'enter' instruction, or by 'subl $<size>, %esp'. 'enter' has | |
356 | * a 16 bit unsigned argument for space to allocate, and the | |
357 | * 'addl' instruction could have either a signed byte, or | |
358 | * 32 bit immediate. | |
359 | * | |
360 | * Next, the registers used by this function are pushed. In | |
361 | * the sys5 compiler they will always be in the order: %edi, %esi, %ebx | |
362 | * (and sometimes a harmless bug causes it to also save but not restore %eax); | |
363 | * however, the code below is willing to see the pushes in any order, | |
364 | * and will handle up to 8 of them. | |
365 | * | |
366 | * If the setup sequence is at the end of the function, then the | |
367 | * next instruction will be a branch back to the start. | |
368 | */ | |
369 | ||
370 | i386_frame_find_saved_regs (fip, fsrp) | |
371 | struct frame_info *fip; | |
372 | struct frame_saved_regs *fsrp; | |
373 | { | |
374 | long locals; | |
375 | unsigned char *p; | |
376 | unsigned char op; | |
377 | CORE_ADDR dummy_bottom; | |
378 | CORE_ADDR adr; | |
379 | int i; | |
380 | ||
381 | bzero (fsrp, sizeof *fsrp); | |
382 | ||
383 | /* if frame is the end of a dummy, compute where the | |
384 | * beginning would be | |
385 | */ | |
386 | dummy_bottom = fip->frame - 4 - REGISTER_BYTES - CALL_DUMMY_LENGTH; | |
387 | ||
388 | /* check if the PC is in the stack, in a dummy frame */ | |
389 | if (dummy_bottom <= fip->pc && fip->pc <= fip->frame) | |
390 | { | |
391 | /* all regs were saved by push_call_dummy () */ | |
392 | adr = fip->frame; | |
393 | for (i = 0; i < NUM_REGS; i++) | |
394 | { | |
395 | adr -= REGISTER_RAW_SIZE (i); | |
396 | fsrp->regs[i] = adr; | |
397 | } | |
398 | return; | |
399 | } | |
400 | ||
401 | locals = i386_get_frame_setup (get_pc_function_start (fip->pc)); | |
402 | ||
403 | if (locals >= 0) | |
404 | { | |
405 | adr = fip->frame - 4 - locals; | |
406 | for (i = 0; i < 8; i++) | |
407 | { | |
408 | op = codestream_get (); | |
409 | if (op < 0x50 || op > 0x57) | |
410 | break; | |
411 | fsrp->regs[op - 0x50] = adr; | |
412 | adr -= 4; | |
413 | } | |
414 | } | |
415 | ||
416 | fsrp->regs[PC_REGNUM] = fip->frame + 4; | |
417 | fsrp->regs[FP_REGNUM] = fip->frame; | |
418 | } | |
419 | ||
420 | /* return pc of first real instruction */ | |
421 | i386_skip_prologue (pc) | |
422 | { | |
423 | unsigned char op; | |
424 | int i; | |
425 | ||
426 | if (i386_get_frame_setup (pc) < 0) | |
427 | return (pc); | |
428 | ||
429 | /* found valid frame setup - codestream now points to | |
430 | * start of push instructions for saving registers | |
431 | */ | |
432 | ||
433 | /* skip over register saves */ | |
434 | for (i = 0; i < 8; i++) | |
435 | { | |
436 | op = codestream_peek (); | |
437 | /* break if not pushl inst */ | |
438 | if (op < 0x50 || op > 0x57) | |
439 | break; | |
440 | codestream_get (); | |
441 | } | |
442 | ||
443 | i386_follow_jump (); | |
444 | ||
445 | return (codestream_tell ()); | |
446 | } | |
447 | ||
448 | i386_push_dummy_frame () | |
449 | { | |
450 | CORE_ADDR sp = read_register (SP_REGNUM); | |
451 | int regnum; | |
452 | char regbuf[MAX_REGISTER_RAW_SIZE]; | |
453 | ||
454 | sp = push_word (sp, read_register (PC_REGNUM)); | |
455 | sp = push_word (sp, read_register (FP_REGNUM)); | |
456 | write_register (FP_REGNUM, sp); | |
457 | for (regnum = 0; regnum < NUM_REGS; regnum++) | |
458 | { | |
459 | read_register_gen (regnum, regbuf); | |
460 | sp = push_bytes (sp, regbuf, REGISTER_RAW_SIZE (regnum)); | |
461 | } | |
462 | write_register (SP_REGNUM, sp); | |
463 | } | |
464 | ||
465 | i386_pop_frame () | |
466 | { | |
467 | FRAME frame = get_current_frame (); | |
468 | CORE_ADDR fp; | |
469 | int regnum; | |
470 | struct frame_saved_regs fsr; | |
471 | struct frame_info *fi; | |
472 | char regbuf[MAX_REGISTER_RAW_SIZE]; | |
473 | ||
474 | fi = get_frame_info (frame); | |
475 | fp = fi->frame; | |
476 | get_frame_saved_regs (fi, &fsr); | |
477 | for (regnum = 0; regnum < NUM_REGS; regnum++) | |
478 | { | |
479 | CORE_ADDR adr; | |
480 | adr = fsr.regs[regnum]; | |
481 | if (adr) | |
482 | { | |
483 | read_memory (adr, regbuf, REGISTER_RAW_SIZE (regnum)); | |
484 | write_register_bytes (REGISTER_BYTE (regnum), regbuf, | |
485 | REGISTER_RAW_SIZE (regnum)); | |
486 | } | |
487 | } | |
488 | write_register (FP_REGNUM, read_memory_integer (fp, 4)); | |
489 | write_register (PC_REGNUM, read_memory_integer (fp + 4, 4)); | |
490 | write_register (SP_REGNUM, fp + 8); | |
491 | flush_cached_frames (); | |
492 | set_current_frame ( create_new_frame (read_register (FP_REGNUM), | |
493 | read_pc ())); | |
494 | } |