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1 | /* Target-dependent code for the ALPHA architecture, for GDB, the GNU Debugger. |
2 | Copyright 1993 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | This program 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 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program 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 this program; if not, write to the Free Software | |
18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | #include "defs.h" | |
21 | #include "frame.h" | |
22 | #include "inferior.h" | |
23 | #include "symtab.h" | |
24 | #include "value.h" | |
25 | #include "gdbcmd.h" | |
26 | #include "gdbcore.h" | |
27 | #include "dis-asm.h" | |
28 | ||
29 | /* FIXME: Some of this code should perhaps be merged with mips-tdep.c. */ | |
30 | ||
31 | #define VM_MIN_ADDRESS (CORE_ADDR)0x120000000 | |
32 | \f | |
33 | ||
34 | /* Forward declarations. */ | |
35 | ||
36 | static CORE_ADDR | |
37 | read_next_frame_reg PARAMS ((FRAME, int)); | |
38 | ||
39 | static CORE_ADDR | |
40 | heuristic_proc_start PARAMS ((CORE_ADDR)); | |
41 | ||
42 | static alpha_extra_func_info_t | |
43 | heuristic_proc_desc PARAMS ((CORE_ADDR, CORE_ADDR, FRAME)); | |
44 | ||
45 | static alpha_extra_func_info_t | |
46 | find_proc_desc PARAMS ((CORE_ADDR, FRAME)); | |
47 | ||
48 | static int | |
49 | alpha_in_lenient_prologue PARAMS ((CORE_ADDR, CORE_ADDR)); | |
50 | ||
51 | static void | |
52 | reinit_frame_cache_sfunc PARAMS ((char *, int, struct cmd_list_element *)); | |
53 | ||
54 | void | |
55 | _initialize_alpha_tdep PARAMS ((void)); | |
56 | ||
57 | /* Heuristic_proc_start may hunt through the text section for a long | |
58 | time across a 2400 baud serial line. Allows the user to limit this | |
59 | search. */ | |
60 | static unsigned int heuristic_fence_post = 0; | |
61 | ||
62 | /* Layout of a stack frame on the alpha: | |
63 | ||
64 | | | | |
65 | pdr members: | 7th ... nth arg, | | |
66 | | `pushed' by caller. | | |
67 | | | | |
68 | ----------------|-------------------------------|<-- old_sp == vfp | |
69 | ^ ^ ^ ^ | | | |
70 | | | | | | | | |
71 | | |localoff | Copies of 1st .. 6th | | |
72 | | | | | | argument if necessary. | | |
73 | | | | v | | | |
74 | | | | --- |-------------------------------|<-- FRAME_ARGS_ADDRESS, | |
75 | | | | | | FRAME_LOCALS_ADDRESS | |
76 | | | | | Locals and temporaries. | | |
77 | | | | | | | |
78 | | | | |-------------------------------| | |
79 | | | | | | | |
80 | |-fregoffset | Saved float registers. | | |
81 | | | | | F9 | | |
82 | | | | | . | | |
83 | | | | | . | | |
84 | | | | | F2 | | |
85 | | | v | | | |
86 | | | -------|-------------------------------| | |
87 | | | | | | |
88 | | | | Saved registers. | | |
89 | | | | S6 | | |
90 | |-regoffset | . | | |
91 | | | | . | | |
92 | | | | S0 | | |
93 | | | | pdr.pcreg | | |
94 | | v | | | |
95 | | ----------|-------------------------------| | |
96 | | | | | |
97 | frameoffset | Argument build area, gets | | |
98 | | | 7th ... nth arg for any | | |
99 | | | called procedure. | | |
100 | v | | | |
101 | -------------|-------------------------------|<-- sp | |
102 | | | | |
103 | */ | |
104 | ||
105 | #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr) /* least address */ | |
106 | #define PROC_HIGH_ADDR(proc) ((proc)->pdr.iline) /* upper address bound */ | |
107 | #define PROC_DUMMY_FRAME(proc) ((proc)->pdr.iopt) /* frame for CALL_DUMMY */ | |
108 | #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset) | |
109 | #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg) | |
110 | #define PROC_REG_MASK(proc) ((proc)->pdr.regmask) | |
111 | #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask) | |
112 | #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset) | |
113 | #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset) | |
114 | #define PROC_PC_REG(proc) ((proc)->pdr.pcreg) | |
115 | #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff) | |
116 | #define PROC_SYMBOL(proc) (*(struct symbol**)&(proc)->pdr.isym) | |
117 | #define _PROC_MAGIC_ 0x0F0F0F0F | |
118 | #define PROC_DESC_IS_DUMMY(proc) ((proc)->pdr.isym == _PROC_MAGIC_) | |
119 | #define SET_PROC_DESC_IS_DUMMY(proc) ((proc)->pdr.isym = _PROC_MAGIC_) | |
120 | ||
121 | struct linked_proc_info | |
122 | { | |
123 | struct alpha_extra_func_info info; | |
124 | struct linked_proc_info *next; | |
125 | } *linked_proc_desc_table = NULL; | |
126 | ||
127 | \f | |
128 | #define READ_FRAME_REG(fi, regno) read_next_frame_reg((fi)->next, regno) | |
129 | ||
130 | static CORE_ADDR | |
131 | read_next_frame_reg(fi, regno) | |
132 | FRAME fi; | |
133 | int regno; | |
134 | { | |
135 | /* If it is the frame for sigtramp we have a pointer to the sigcontext | |
136 | on the stack. | |
137 | If the stack layout for __sigtramp changes or if sigcontext offsets | |
138 | change we might have to update this code. */ | |
139 | #ifndef SIGFRAME_PC_OFF | |
140 | #define SIGFRAME_PC_OFF (2 * 8) | |
141 | #define SIGFRAME_REGSAVE_OFF (4 * 8) | |
142 | #endif | |
143 | for (; fi; fi = fi->next) | |
144 | { | |
145 | if (fi->signal_handler_caller) | |
146 | { | |
147 | int offset; | |
148 | CORE_ADDR sigcontext_addr = read_memory_integer(fi->frame, 8); | |
149 | ||
150 | if (regno == PC_REGNUM) | |
151 | offset = SIGFRAME_PC_OFF; | |
152 | else if (regno < 32) | |
153 | offset = SIGFRAME_REGSAVE_OFF + regno * 8; | |
154 | else | |
155 | return 0; | |
156 | return read_memory_integer(sigcontext_addr + offset, 8); | |
157 | } | |
158 | else if (regno == SP_REGNUM) | |
159 | return fi->frame; | |
160 | else if (fi->saved_regs->regs[regno]) | |
161 | return read_memory_integer(fi->saved_regs->regs[regno], 8); | |
162 | } | |
163 | return read_register(regno); | |
164 | } | |
165 | ||
166 | CORE_ADDR | |
167 | alpha_frame_saved_pc(frame) | |
168 | FRAME frame; | |
169 | { | |
170 | alpha_extra_func_info_t proc_desc = frame->proc_desc; | |
171 | int pcreg = proc_desc ? PROC_PC_REG(proc_desc) : RA_REGNUM; | |
172 | ||
173 | if (proc_desc && PROC_DESC_IS_DUMMY(proc_desc)) | |
174 | return read_memory_integer(frame->frame - 8, 8); | |
175 | ||
176 | return read_next_frame_reg(frame, pcreg); | |
177 | } | |
178 | ||
179 | CORE_ADDR | |
180 | alpha_saved_pc_after_call (frame) | |
181 | FRAME frame; | |
182 | { | |
183 | alpha_extra_func_info_t proc_desc = find_proc_desc (frame->pc, frame->next); | |
184 | int pcreg = proc_desc ? PROC_PC_REG (proc_desc) : RA_REGNUM; | |
185 | ||
186 | return read_register (pcreg); | |
187 | } | |
188 | ||
189 | ||
190 | static struct alpha_extra_func_info temp_proc_desc; | |
191 | static struct frame_saved_regs temp_saved_regs; | |
192 | ||
193 | /* This fencepost looks highly suspicious to me. Removing it also | |
194 | seems suspicious as it could affect remote debugging across serial | |
195 | lines. */ | |
196 | ||
197 | static CORE_ADDR | |
198 | heuristic_proc_start(pc) | |
199 | CORE_ADDR pc; | |
200 | { | |
201 | CORE_ADDR start_pc = pc; | |
202 | CORE_ADDR fence = start_pc - heuristic_fence_post; | |
203 | ||
204 | if (start_pc == 0) return 0; | |
205 | ||
206 | if (heuristic_fence_post == UINT_MAX | |
207 | || fence < VM_MIN_ADDRESS) | |
208 | fence = VM_MIN_ADDRESS; | |
209 | ||
210 | /* search back for previous return */ | |
211 | for (start_pc -= 4; ; start_pc -= 4) | |
212 | if (start_pc < fence) | |
213 | { | |
214 | /* It's not clear to me why we reach this point when | |
215 | stop_soon_quietly, but with this test, at least we | |
216 | don't print out warnings for every child forked (eg, on | |
217 | decstation). 22apr93 rich@cygnus.com. */ | |
218 | if (!stop_soon_quietly) | |
219 | { | |
220 | static int blurb_printed = 0; | |
221 | ||
222 | if (fence == VM_MIN_ADDRESS) | |
223 | warning("Hit beginning of text section without finding"); | |
224 | else | |
225 | warning("Hit heuristic-fence-post without finding"); | |
226 | ||
227 | warning("enclosing function for address 0x%lx", pc); | |
228 | if (!blurb_printed) | |
229 | { | |
230 | printf_filtered ("\ | |
231 | This warning occurs if you are debugging a function without any symbols\n\ | |
232 | (for example, in a stripped executable). In that case, you may wish to\n\ | |
233 | increase the size of the search with the `set heuristic-fence-post' command.\n\ | |
234 | \n\ | |
235 | Otherwise, you told GDB there was a function where there isn't one, or\n\ | |
236 | (more likely) you have encountered a bug in GDB.\n"); | |
237 | blurb_printed = 1; | |
238 | } | |
239 | } | |
240 | ||
241 | return 0; | |
242 | } | |
243 | else if (ABOUT_TO_RETURN(start_pc)) | |
244 | break; | |
245 | ||
246 | start_pc += 4; /* skip return */ | |
247 | return start_pc; | |
248 | } | |
249 | ||
250 | static alpha_extra_func_info_t | |
251 | heuristic_proc_desc(start_pc, limit_pc, next_frame) | |
252 | CORE_ADDR start_pc, limit_pc; | |
253 | FRAME next_frame; | |
254 | { | |
255 | CORE_ADDR sp = next_frame ? next_frame->frame : read_register (SP_REGNUM); | |
256 | CORE_ADDR cur_pc; | |
257 | int frame_size; | |
258 | int has_frame_reg = 0; | |
259 | unsigned long reg_mask = 0; | |
260 | ||
261 | if (start_pc == 0) | |
262 | return NULL; | |
263 | memset(&temp_proc_desc, '\0', sizeof(temp_proc_desc)); | |
264 | memset(&temp_saved_regs, '\0', sizeof(struct frame_saved_regs)); | |
265 | PROC_LOW_ADDR(&temp_proc_desc) = start_pc; | |
266 | ||
267 | if (start_pc + 200 < limit_pc) | |
268 | limit_pc = start_pc + 200; | |
269 | frame_size = 0; | |
270 | for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += 4) | |
271 | { | |
272 | char buf[4]; | |
273 | unsigned long word; | |
274 | int status; | |
275 | ||
276 | status = read_memory_nobpt (cur_pc, buf, 4); | |
277 | if (status) | |
278 | memory_error (status, cur_pc); | |
279 | word = extract_unsigned_integer (buf, 4); | |
280 | ||
281 | if ((word & 0xffff0000) == 0x23de0000) /* lda $sp,n($sp) */ | |
282 | frame_size += (-word) & 0xffff; | |
283 | else if ((word & 0xfc1f0000) == 0xb41e0000 /* stq reg,n($sp) */ | |
284 | && (word & 0xffff0000) != 0xb7fe0000) /* reg != $zero */ | |
285 | { | |
286 | int reg = (word & 0x03e00000) >> 21; | |
287 | reg_mask |= 1 << reg; | |
288 | temp_saved_regs.regs[reg] = sp + (short)word; | |
289 | } | |
290 | else if (word == 0x47de040f) /* bis sp,sp fp */ | |
291 | has_frame_reg = 1; | |
292 | } | |
293 | if (has_frame_reg) | |
294 | PROC_FRAME_REG(&temp_proc_desc) = GCC_FP_REGNUM; | |
295 | else | |
296 | PROC_FRAME_REG(&temp_proc_desc) = SP_REGNUM; | |
297 | PROC_FRAME_OFFSET(&temp_proc_desc) = frame_size; | |
298 | PROC_REG_MASK(&temp_proc_desc) = reg_mask; | |
299 | PROC_PC_REG(&temp_proc_desc) = RA_REGNUM; | |
300 | return &temp_proc_desc; | |
301 | } | |
302 | ||
303 | static alpha_extra_func_info_t | |
304 | find_proc_desc(pc, next_frame) | |
305 | CORE_ADDR pc; | |
306 | FRAME next_frame; | |
307 | { | |
308 | alpha_extra_func_info_t proc_desc; | |
309 | struct block *b; | |
310 | struct symbol *sym; | |
311 | CORE_ADDR startaddr; | |
312 | ||
313 | /* Try to get the proc_desc from the linked call dummy proc_descs | |
314 | if the pc is in the call dummy. | |
315 | This is hairy. In the case of nested dummy calls we have to find the | |
316 | right proc_desc, but we might not yet know the frame for the dummy | |
317 | as it will be contained in the proc_desc we are searching for. | |
318 | So we have to find the proc_desc whose frame is closest to the current | |
319 | stack pointer. */ | |
320 | if (PC_IN_CALL_DUMMY (pc, 0, 0)) | |
321 | { | |
322 | struct linked_proc_info *link; | |
323 | CORE_ADDR sp = next_frame ? next_frame->frame : read_register (SP_REGNUM); | |
324 | alpha_extra_func_info_t found_proc_desc = NULL; | |
325 | long min_distance = LONG_MAX; | |
326 | ||
327 | for (link = linked_proc_desc_table; link; link = link->next) | |
328 | { | |
329 | long distance = (CORE_ADDR) PROC_DUMMY_FRAME (&link->info) - sp; | |
330 | if (distance > 0 && distance < min_distance) | |
331 | { | |
332 | min_distance = distance; | |
333 | found_proc_desc = &link->info; | |
334 | } | |
335 | } | |
336 | if (found_proc_desc != NULL) | |
337 | return found_proc_desc; | |
338 | } | |
339 | ||
340 | b = block_for_pc(pc); | |
341 | find_pc_partial_function (pc, NULL, &startaddr, NULL); | |
342 | if (b == NULL) | |
343 | sym = NULL; | |
344 | else | |
345 | { | |
346 | if (startaddr > BLOCK_START (b)) | |
347 | /* This is the "pathological" case referred to in a comment in | |
348 | print_frame_info. It might be better to move this check into | |
349 | symbol reading. */ | |
350 | sym = NULL; | |
351 | else | |
352 | sym = lookup_symbol (MIPS_EFI_SYMBOL_NAME, b, LABEL_NAMESPACE, | |
353 | 0, NULL); | |
354 | } | |
355 | ||
356 | if (sym) | |
357 | { | |
358 | /* IF (this is the topmost frame OR a frame interrupted by a signal) | |
359 | * AND (this proc does not have debugging information OR | |
360 | * the PC is in the procedure prologue) | |
361 | * THEN create a "heuristic" proc_desc (by analyzing | |
362 | * the actual code) to replace the "official" proc_desc. | |
363 | */ | |
364 | proc_desc = (alpha_extra_func_info_t)SYMBOL_VALUE(sym); | |
365 | if (next_frame == NULL || next_frame->signal_handler_caller) { | |
366 | struct symtab_and_line val; | |
367 | struct symbol *proc_symbol = | |
368 | PROC_DESC_IS_DUMMY(proc_desc) ? 0 : PROC_SYMBOL(proc_desc); | |
369 | ||
370 | if (proc_symbol) { | |
371 | val = find_pc_line (BLOCK_START | |
372 | (SYMBOL_BLOCK_VALUE(proc_symbol)), | |
373 | 0); | |
374 | val.pc = val.end ? val.end : pc; | |
375 | } | |
376 | if (!proc_symbol || pc < val.pc) { | |
377 | alpha_extra_func_info_t found_heuristic = | |
378 | heuristic_proc_desc(PROC_LOW_ADDR(proc_desc), | |
379 | pc, next_frame); | |
380 | if (found_heuristic) | |
381 | { | |
382 | /* The call to heuristic_proc_desc determines | |
383 | which registers have been saved so far and if the | |
384 | frame is already set up. | |
385 | The heuristic algorithm doesn't work well for other | |
386 | information in the procedure descriptor, so copy | |
387 | it from the found procedure descriptor. */ | |
388 | PROC_LOCALOFF(found_heuristic) = PROC_LOCALOFF(proc_desc); | |
389 | PROC_PC_REG(found_heuristic) = PROC_PC_REG(proc_desc); | |
390 | proc_desc = found_heuristic; | |
391 | } | |
392 | } | |
393 | } | |
394 | } | |
395 | else | |
396 | { | |
397 | if (startaddr == 0) | |
398 | startaddr = heuristic_proc_start (pc); | |
399 | ||
400 | proc_desc = | |
401 | heuristic_proc_desc (startaddr, pc, next_frame); | |
402 | } | |
403 | return proc_desc; | |
404 | } | |
405 | ||
406 | alpha_extra_func_info_t cached_proc_desc; | |
407 | ||
408 | FRAME_ADDR | |
409 | alpha_frame_chain(frame) | |
410 | FRAME frame; | |
411 | { | |
412 | alpha_extra_func_info_t proc_desc; | |
413 | CORE_ADDR saved_pc = FRAME_SAVED_PC(frame); | |
414 | ||
415 | if (saved_pc == 0 || inside_entry_file (saved_pc)) | |
416 | return 0; | |
417 | ||
418 | proc_desc = find_proc_desc(saved_pc, frame); | |
419 | if (!proc_desc) | |
420 | return 0; | |
421 | ||
422 | cached_proc_desc = proc_desc; | |
423 | ||
424 | /* Fetch the frame pointer for a dummy frame from the procedure | |
425 | descriptor. */ | |
426 | if (PROC_DESC_IS_DUMMY(proc_desc)) | |
427 | return (FRAME_ADDR) PROC_DUMMY_FRAME(proc_desc); | |
428 | ||
429 | /* If no frame pointer and frame size is zero, we must be at end | |
430 | of stack (or otherwise hosed). If we don't check frame size, | |
431 | we loop forever if we see a zero size frame. */ | |
432 | if (PROC_FRAME_REG (proc_desc) == SP_REGNUM | |
433 | && PROC_FRAME_OFFSET (proc_desc) == 0 | |
434 | /* The alpha __sigtramp routine is frameless and has a frame size | |
435 | of zero. Luckily it is the only procedure which has PC_REGNUM | |
436 | as PROC_PC_REG. */ | |
437 | && PROC_PC_REG (proc_desc) != PC_REGNUM | |
438 | /* The previous frame from a sigtramp frame might be frameless | |
439 | and have frame size zero. */ | |
440 | && !frame->signal_handler_caller) | |
441 | return 0; | |
442 | else | |
443 | return read_next_frame_reg(frame, PROC_FRAME_REG(proc_desc)) | |
444 | + PROC_FRAME_OFFSET(proc_desc); | |
445 | } | |
446 | ||
447 | void | |
448 | init_extra_frame_info(fci) | |
449 | struct frame_info *fci; | |
450 | { | |
451 | extern struct obstack frame_cache_obstack; | |
452 | /* Use proc_desc calculated in frame_chain */ | |
453 | alpha_extra_func_info_t proc_desc = | |
454 | fci->next ? cached_proc_desc : find_proc_desc(fci->pc, fci->next); | |
455 | ||
456 | fci->saved_regs = (struct frame_saved_regs*) | |
457 | obstack_alloc (&frame_cache_obstack, sizeof(struct frame_saved_regs)); | |
458 | memset (fci->saved_regs, 0, sizeof (struct frame_saved_regs)); | |
459 | fci->proc_desc = | |
460 | proc_desc == &temp_proc_desc ? 0 : proc_desc; | |
461 | if (proc_desc) | |
462 | { | |
463 | int ireg; | |
464 | CORE_ADDR reg_position; | |
465 | unsigned long mask; | |
466 | int returnreg; | |
467 | ||
468 | /* Get the locals offset from the procedure descriptor, it is valid | |
469 | even if we are in the middle of the prologue. */ | |
470 | fci->localoff = PROC_LOCALOFF(proc_desc); | |
471 | ||
472 | /* FIXME: This is a kludge for gcc-2.4.5. | |
473 | gcc-2.4.5 builds frames for the alpha in a peculiar way. | |
474 | It uses $fp as a frame register (which seems to be identical to $sp | |
475 | in all procedures that do not use alloca). | |
476 | It has the arguments and the locals above the frame register, if | |
477 | there are few arguments then the locals are above the arguments, | |
478 | otherwise the arguments are above the local. | |
479 | Frame offsets for arguments and locals are relative to $fp and always | |
480 | positive. | |
481 | If we want to stay compatible with the native cc compiler we have | |
482 | to set localoff to frameoffset so that FRAME_ARGS_ADDRESS and | |
483 | FRAME_LOCALS_ADDRESS point to the right place in the frame. | |
484 | Please note that the setting of localoff in the compiler won't work | |
485 | as localoff is only 8 bits wide (which is enough for cc as it needs | |
486 | at most number_of_arg_regs * 8 == 48). */ | |
487 | if (PROC_FRAME_REG(proc_desc) == GCC_FP_REGNUM) | |
488 | fci->localoff = PROC_FRAME_OFFSET(proc_desc); | |
489 | ||
490 | /* Fixup frame-pointer - only needed for top frame */ | |
491 | /* Fetch the frame pointer for a dummy frame from the procedure | |
492 | descriptor. */ | |
493 | if (PROC_DESC_IS_DUMMY(proc_desc)) | |
494 | fci->frame = (FRAME_ADDR) PROC_DUMMY_FRAME(proc_desc); | |
495 | /* This may not be quite right, if proc has a real frame register. | |
496 | Get the value of the frame relative sp, procedure might have been | |
497 | interrupted by a signal at it's very start. */ | |
498 | else if (fci->pc == PROC_LOW_ADDR(proc_desc)) | |
499 | fci->frame = READ_FRAME_REG(fci, SP_REGNUM); | |
500 | else | |
501 | fci->frame = READ_FRAME_REG(fci, PROC_FRAME_REG(proc_desc)) | |
502 | + PROC_FRAME_OFFSET(proc_desc); | |
503 | ||
504 | /* If this is the innermost frame, and we are still in the | |
505 | prologue (loosely defined), then the registers may not have | |
506 | been saved yet. */ | |
507 | if (fci->next == NULL | |
508 | && !PROC_DESC_IS_DUMMY(proc_desc) | |
509 | && alpha_in_lenient_prologue (PROC_LOW_ADDR (proc_desc), fci->pc)) | |
510 | { | |
511 | /* Can't just say that the registers are not saved, because they | |
512 | might get clobbered halfway through the prologue. | |
513 | heuristic_proc_desc already has the right code to figure out | |
514 | exactly what has been saved, so use it. As far as I know we | |
515 | could be doing this (as we do on the 68k, for example) | |
516 | regardless of whether we are in the prologue; I'm leaving in | |
517 | the check for being in the prologue only out of conservatism | |
518 | (I'm not sure whether heuristic_proc_desc handles all cases, | |
519 | for example). | |
520 | ||
521 | This stuff is ugly (and getting uglier by the minute). Probably | |
522 | the best way to clean it up is to ignore the proc_desc's from | |
523 | the symbols altogher, and get all the information we need by | |
524 | examining the prologue (provided we can make the prologue | |
525 | examining code good enough to get all the cases...). */ | |
526 | proc_desc = | |
527 | heuristic_proc_desc (PROC_LOW_ADDR (proc_desc), | |
528 | fci->pc, | |
529 | fci->next); | |
530 | } | |
531 | ||
532 | if (proc_desc == &temp_proc_desc) | |
533 | *fci->saved_regs = temp_saved_regs; | |
534 | else | |
535 | { | |
536 | /* Find which general-purpose registers were saved. | |
537 | The return address register is the first saved register, | |
538 | the other registers follow in ascending order. */ | |
539 | reg_position = fci->frame + PROC_REG_OFFSET(proc_desc); | |
540 | mask = PROC_REG_MASK(proc_desc) & 0xffffffffL; | |
541 | returnreg = PROC_PC_REG(proc_desc); | |
542 | if (mask & (1 << returnreg)) | |
543 | { | |
544 | fci->saved_regs->regs[returnreg] = reg_position; | |
545 | reg_position += 8; | |
546 | } | |
547 | for (ireg = 0; mask; ireg++, mask >>= 1) | |
548 | if (mask & 1) | |
549 | { | |
550 | if (ireg == returnreg) | |
551 | continue; | |
552 | fci->saved_regs->regs[ireg] = reg_position; | |
553 | reg_position += 8; | |
554 | } | |
555 | /* find which floating-point registers were saved */ | |
556 | reg_position = fci->frame + PROC_FREG_OFFSET(proc_desc); | |
557 | mask = PROC_FREG_MASK(proc_desc) & 0xffffffffL; | |
558 | for (ireg = 0; mask; ireg++, mask >>= 1) | |
559 | if (mask & 1) | |
560 | { | |
561 | fci->saved_regs->regs[FP0_REGNUM+ireg] = reg_position; | |
562 | reg_position += 8; | |
563 | } | |
564 | } | |
565 | ||
566 | fci->saved_regs->regs[PC_REGNUM] = fci->saved_regs->regs[PROC_PC_REG(proc_desc)]; | |
567 | } | |
568 | } | |
569 | ||
570 | /* ALPHA stack frames are almost impenetrable. When execution stops, | |
571 | we basically have to look at symbol information for the function | |
572 | that we stopped in, which tells us *which* register (if any) is | |
573 | the base of the frame pointer, and what offset from that register | |
574 | the frame itself is at. | |
575 | ||
576 | This presents a problem when trying to examine a stack in memory | |
577 | (that isn't executing at the moment), using the "frame" command. We | |
578 | don't have a PC, nor do we have any registers except SP. | |
579 | ||
580 | This routine takes two arguments, SP and PC, and tries to make the | |
581 | cached frames look as if these two arguments defined a frame on the | |
582 | cache. This allows the rest of info frame to extract the important | |
583 | arguments without difficulty. */ | |
584 | ||
585 | FRAME | |
586 | setup_arbitrary_frame (argc, argv) | |
587 | int argc; | |
588 | FRAME_ADDR *argv; | |
589 | { | |
590 | if (argc != 2) | |
591 | error ("ALPHA frame specifications require two arguments: sp and pc"); | |
592 | ||
593 | return create_new_frame (argv[0], argv[1]); | |
594 | } | |
595 | ||
596 | /* The alpha passes the first six arguments in the registers, the rest on | |
597 | the stack. The register arguments are eventually transferred to the | |
598 | argument transfer area immediately below the stack by the called function | |
599 | anyway. So we `push' at least six arguments on the stack, `reload' the | |
600 | argument registers and then adjust the stack pointer to point past the | |
601 | sixth argument. This algorithm simplifies the passing of a large struct | |
602 | which extends from the registers to the stack. | |
603 | If the called function is returning a structure, the address of the | |
604 | structure to be returned is passed as a hidden first argument. */ | |
605 | ||
606 | #define NUM_ARG_REGS 6 | |
607 | ||
608 | CORE_ADDR | |
609 | alpha_push_arguments (nargs, args, sp, struct_return, struct_addr) | |
610 | int nargs; | |
611 | value *args; | |
612 | CORE_ADDR sp; | |
613 | int struct_return; | |
614 | CORE_ADDR struct_addr; | |
615 | { | |
616 | register i; | |
617 | int accumulate_size = struct_return ? 8 : 0; | |
618 | int arg_regs_size = NUM_ARG_REGS * 8; | |
619 | struct alpha_arg { char *contents; int len; int offset; }; | |
620 | struct alpha_arg *alpha_args = | |
621 | (struct alpha_arg*)alloca (nargs * sizeof (struct alpha_arg)); | |
622 | register struct alpha_arg *m_arg; | |
623 | char raw_buffer[sizeof (CORE_ADDR)]; | |
624 | int required_arg_regs; | |
625 | ||
626 | for (i = 0, m_arg = alpha_args; i < nargs; i++, m_arg++) | |
627 | { | |
628 | value arg = value_arg_coerce (args[i]); | |
629 | /* Cast argument to long if necessary as the compiler does it too. */ | |
630 | if (TYPE_LENGTH (VALUE_TYPE (arg)) < TYPE_LENGTH (builtin_type_long)) | |
631 | arg = value_cast (builtin_type_long, arg); | |
632 | m_arg->len = TYPE_LENGTH (VALUE_TYPE (arg)); | |
633 | m_arg->offset = accumulate_size; | |
634 | accumulate_size = (accumulate_size + m_arg->len + 7) & ~7; | |
635 | m_arg->contents = VALUE_CONTENTS(arg); | |
636 | } | |
637 | ||
638 | /* Determine required argument register loads, loading an argument register | |
639 | is expensive as it uses three ptrace calls. */ | |
640 | required_arg_regs = accumulate_size / 8; | |
641 | if (required_arg_regs > NUM_ARG_REGS) | |
642 | required_arg_regs = NUM_ARG_REGS; | |
643 | ||
644 | /* Make room for the arguments on the stack. */ | |
645 | if (accumulate_size < arg_regs_size) | |
646 | accumulate_size = arg_regs_size; | |
647 | sp -= accumulate_size; | |
648 | ||
649 | /* Keep sp aligned to a multiple of 16 as the compiler does it too. */ | |
650 | sp &= ~15; | |
651 | ||
652 | /* `Push' arguments on the stack. */ | |
653 | for (i = nargs; m_arg--, --i >= 0; ) | |
654 | write_memory(sp + m_arg->offset, m_arg->contents, m_arg->len); | |
655 | if (struct_return) | |
656 | { | |
657 | store_address (raw_buffer, sizeof (CORE_ADDR), struct_addr); | |
658 | write_memory (sp, raw_buffer, sizeof (CORE_ADDR)); | |
659 | } | |
660 | ||
661 | /* Load the argument registers. */ | |
662 | for (i = 0; i < required_arg_regs; i++) | |
663 | { | |
664 | LONGEST val; | |
665 | ||
666 | val = read_memory_integer (sp + i * 8, 8); | |
667 | write_register (A0_REGNUM + i, val); | |
668 | write_register (FPA0_REGNUM + i, val); | |
669 | } | |
670 | ||
671 | return sp + arg_regs_size; | |
672 | } | |
673 | ||
674 | void | |
675 | alpha_push_dummy_frame() | |
676 | { | |
677 | int ireg; | |
678 | struct linked_proc_info *link = (struct linked_proc_info*) | |
679 | xmalloc(sizeof (struct linked_proc_info)); | |
680 | alpha_extra_func_info_t proc_desc = &link->info; | |
681 | CORE_ADDR sp = read_register (SP_REGNUM); | |
682 | CORE_ADDR save_address; | |
683 | char raw_buffer[MAX_REGISTER_RAW_SIZE]; | |
684 | unsigned long mask; | |
685 | ||
686 | link->next = linked_proc_desc_table; | |
687 | linked_proc_desc_table = link; | |
688 | ||
689 | /* | |
690 | * The registers we must save are all those not preserved across | |
691 | * procedure calls. | |
692 | * In addition, we must save the PC and RA. | |
693 | * | |
694 | * Dummy frame layout: | |
695 | * (high memory) | |
696 | * Saved PC | |
697 | * Saved F30 | |
698 | * ... | |
699 | * Saved F0 | |
700 | * Saved R29 | |
701 | * ... | |
702 | * Saved R0 | |
703 | * Saved R26 (RA) | |
704 | * Parameter build area | |
705 | * (low memory) | |
706 | */ | |
707 | ||
708 | /* MASK(i,j) == (1<<i) + (1<<(i+1)) + ... + (1<<j)). Assume i<=j<31. */ | |
709 | #define MASK(i,j) (((1L << ((j)+1)) - 1) ^ ((1L << (i)) - 1)) | |
710 | #define GEN_REG_SAVE_MASK (MASK(0,8) | MASK(16,29)) | |
711 | #define GEN_REG_SAVE_COUNT 24 | |
712 | #define FLOAT_REG_SAVE_MASK (MASK(0,1) | MASK(10,30)) | |
713 | #define FLOAT_REG_SAVE_COUNT 23 | |
714 | /* The special register is the PC as we have no bit for it in the save masks. | |
715 | alpha_frame_saved_pc knows where the pc is saved in a dummy frame. */ | |
716 | #define SPECIAL_REG_SAVE_COUNT 1 | |
717 | ||
718 | PROC_REG_MASK(proc_desc) = GEN_REG_SAVE_MASK; | |
719 | PROC_FREG_MASK(proc_desc) = FLOAT_REG_SAVE_MASK; | |
720 | /* PROC_REG_OFFSET is the offset from the dummy frame to the saved RA, | |
721 | but keep SP aligned to a multiple of 16. */ | |
722 | PROC_REG_OFFSET(proc_desc) = | |
723 | - ((8 * (SPECIAL_REG_SAVE_COUNT | |
724 | + GEN_REG_SAVE_COUNT | |
725 | + FLOAT_REG_SAVE_COUNT) | |
726 | + 15) & ~15); | |
727 | PROC_FREG_OFFSET(proc_desc) = | |
728 | PROC_REG_OFFSET(proc_desc) + 8 * GEN_REG_SAVE_COUNT; | |
729 | ||
730 | /* Save general registers. | |
731 | The return address register is the first saved register, all other | |
732 | registers follow in ascending order. | |
733 | The PC is saved immediately below the SP. */ | |
734 | save_address = sp + PROC_REG_OFFSET(proc_desc); | |
735 | store_address (raw_buffer, 8, read_register (RA_REGNUM)); | |
736 | write_memory (save_address, raw_buffer, 8); | |
737 | save_address += 8; | |
738 | mask = PROC_REG_MASK(proc_desc) & 0xffffffffL; | |
739 | for (ireg = 0; mask; ireg++, mask >>= 1) | |
740 | if (mask & 1) | |
741 | { | |
742 | if (ireg == RA_REGNUM) | |
743 | continue; | |
744 | store_address (raw_buffer, 8, read_register (ireg)); | |
745 | write_memory (save_address, raw_buffer, 8); | |
746 | save_address += 8; | |
747 | } | |
748 | ||
749 | store_address (raw_buffer, 8, read_register (PC_REGNUM)); | |
750 | write_memory (sp - 8, raw_buffer, 8); | |
751 | ||
752 | /* Save floating point registers. */ | |
753 | save_address = sp + PROC_FREG_OFFSET(proc_desc); | |
754 | mask = PROC_FREG_MASK(proc_desc) & 0xffffffffL; | |
755 | for (ireg = 0; mask; ireg++, mask >>= 1) | |
756 | if (mask & 1) | |
757 | { | |
758 | store_address (raw_buffer, 8, read_register (ireg + FP0_REGNUM)); | |
759 | write_memory (save_address, raw_buffer, 8); | |
760 | save_address += 8; | |
761 | } | |
762 | ||
763 | /* Set and save the frame address for the dummy. | |
764 | This is tricky. The only registers that are suitable for a frame save | |
765 | are those that are preserved across procedure calls (s0-s6). But if | |
766 | a read system call is interrupted and then a dummy call is made | |
767 | (see testsuite/gdb.t17/interrupt.exp) the dummy call hangs till the read | |
768 | is satisfied. Then it returns with the s0-s6 registers set to the values | |
769 | on entry to the read system call and our dummy frame pointer would be | |
770 | destroyed. So we save the dummy frame in the proc_desc and handle the | |
771 | retrieval of the frame pointer of a dummy specifically. The frame register | |
772 | is set to the virtual frame (pseudo) register, it's value will always | |
773 | be read as zero and will help us to catch any errors in the dummy frame | |
774 | retrieval code. */ | |
775 | PROC_DUMMY_FRAME(proc_desc) = sp; | |
776 | PROC_FRAME_REG(proc_desc) = FP_REGNUM; | |
777 | PROC_FRAME_OFFSET(proc_desc) = 0; | |
778 | sp += PROC_REG_OFFSET(proc_desc); | |
779 | write_register (SP_REGNUM, sp); | |
780 | ||
781 | PROC_LOW_ADDR(proc_desc) = entry_point_address (); | |
782 | PROC_HIGH_ADDR(proc_desc) = PROC_LOW_ADDR(proc_desc) + 4; | |
783 | ||
784 | SET_PROC_DESC_IS_DUMMY(proc_desc); | |
785 | PROC_PC_REG(proc_desc) = RA_REGNUM; | |
786 | } | |
787 | ||
788 | void | |
789 | alpha_pop_frame() | |
790 | { | |
791 | register int regnum; | |
792 | FRAME frame = get_current_frame (); | |
793 | CORE_ADDR new_sp = frame->frame; | |
794 | ||
795 | alpha_extra_func_info_t proc_desc = frame->proc_desc; | |
796 | ||
797 | write_register (PC_REGNUM, FRAME_SAVED_PC(frame)); | |
798 | if (proc_desc) | |
799 | { | |
800 | for (regnum = 32; --regnum >= 0; ) | |
801 | if (PROC_REG_MASK(proc_desc) & (1 << regnum)) | |
802 | write_register (regnum, | |
803 | read_memory_integer (frame->saved_regs->regs[regnum], | |
804 | 8)); | |
805 | for (regnum = 32; --regnum >= 0; ) | |
806 | if (PROC_FREG_MASK(proc_desc) & (1 << regnum)) | |
807 | write_register (regnum + FP0_REGNUM, | |
808 | read_memory_integer (frame->saved_regs->regs[regnum + FP0_REGNUM], 8)); | |
809 | } | |
810 | write_register (SP_REGNUM, new_sp); | |
811 | flush_cached_frames (); | |
812 | /* We let init_extra_frame_info figure out the frame pointer */ | |
813 | set_current_frame (create_new_frame (0, read_pc ())); | |
814 | ||
815 | if (proc_desc && PROC_DESC_IS_DUMMY(proc_desc)) | |
816 | { | |
817 | struct linked_proc_info *pi_ptr, *prev_ptr; | |
818 | ||
819 | for (pi_ptr = linked_proc_desc_table, prev_ptr = NULL; | |
820 | pi_ptr != NULL; | |
821 | prev_ptr = pi_ptr, pi_ptr = pi_ptr->next) | |
822 | { | |
823 | if (&pi_ptr->info == proc_desc) | |
824 | break; | |
825 | } | |
826 | ||
827 | if (pi_ptr == NULL) | |
828 | error ("Can't locate dummy extra frame info\n"); | |
829 | ||
830 | if (prev_ptr != NULL) | |
831 | prev_ptr->next = pi_ptr->next; | |
832 | else | |
833 | linked_proc_desc_table = pi_ptr->next; | |
834 | ||
835 | free (pi_ptr); | |
836 | } | |
837 | } | |
838 | \f | |
839 | /* To skip prologues, I use this predicate. Returns either PC itself | |
840 | if the code at PC does not look like a function prologue; otherwise | |
841 | returns an address that (if we're lucky) follows the prologue. If | |
842 | LENIENT, then we must skip everything which is involved in setting | |
843 | up the frame (it's OK to skip more, just so long as we don't skip | |
844 | anything which might clobber the registers which are being saved. | |
845 | Currently we must not skip more on the alpha, but we might the lenient | |
846 | stuff some day. */ | |
847 | ||
848 | CORE_ADDR | |
849 | alpha_skip_prologue (pc, lenient) | |
850 | CORE_ADDR pc; | |
851 | int lenient; | |
852 | { | |
853 | unsigned long inst; | |
854 | int offset; | |
855 | ||
856 | /* Skip the typical prologue instructions. These are the stack adjustment | |
857 | instruction and the instructions that save registers on the stack | |
858 | or in the gcc frame. */ | |
859 | for (offset = 0; offset < 100; offset += 4) | |
860 | { | |
861 | char buf[4]; | |
862 | int status; | |
863 | ||
864 | status = read_memory_nobpt (pc + offset, buf, 4); | |
865 | if (status) | |
866 | memory_error (status, pc + offset); | |
867 | inst = extract_unsigned_integer (buf, 4); | |
868 | ||
869 | /* The alpha has no delay slots. But let's keep the lenient stuff, | |
870 | we might need it for something else in the future. */ | |
871 | if (lenient && 0) | |
872 | continue; | |
873 | ||
874 | if ((inst & 0xffff0000) == 0x27bb0000) /* ldah $gp,n($t12) */ | |
875 | continue; | |
876 | if ((inst & 0xffff0000) == 0x23bd0000) /* lda $gp,n($gp) */ | |
877 | continue; | |
878 | if ((inst & 0xffff0000) == 0x23de0000) /* lda $sp,n($sp) */ | |
879 | continue; | |
880 | else if ((inst & 0xfc1f0000) == 0xb41e0000 | |
881 | && (inst & 0xffff0000) != 0xb7fe0000) | |
882 | continue; /* stq reg,n($sp) */ | |
883 | /* reg != $zero */ | |
884 | else if ((inst & 0xfc1f0000) == 0x9c1e0000 | |
885 | && (inst & 0xffff0000) != 0x9ffe0000) | |
886 | continue; /* stt reg,n($sp) */ | |
887 | /* reg != $zero */ | |
888 | else if (inst == 0x47de040f) /* bis sp,sp,fp */ | |
889 | continue; | |
890 | else | |
891 | break; | |
892 | } | |
893 | return pc + offset; | |
894 | } | |
895 | ||
896 | /* Is address PC in the prologue (loosely defined) for function at | |
897 | STARTADDR? */ | |
898 | ||
899 | static int | |
900 | alpha_in_lenient_prologue (startaddr, pc) | |
901 | CORE_ADDR startaddr; | |
902 | CORE_ADDR pc; | |
903 | { | |
904 | CORE_ADDR end_prologue = alpha_skip_prologue (startaddr, 1); | |
905 | return pc >= startaddr && pc < end_prologue; | |
906 | } | |
907 | ||
908 | /* Given a return value in `regbuf' with a type `valtype', | |
909 | extract and copy its value into `valbuf'. */ | |
910 | void | |
911 | alpha_extract_return_value (valtype, regbuf, valbuf) | |
912 | struct type *valtype; | |
913 | char regbuf[REGISTER_BYTES]; | |
914 | char *valbuf; | |
915 | { | |
916 | int regnum; | |
917 | ||
918 | regnum = TYPE_CODE (valtype) == TYPE_CODE_FLT ? FP0_REGNUM : V0_REGNUM; | |
919 | ||
920 | memcpy (valbuf, regbuf + REGISTER_BYTE (regnum), TYPE_LENGTH (valtype)); | |
921 | } | |
922 | ||
923 | /* Given a return value in `regbuf' with a type `valtype', | |
924 | write it's value into the appropriate register. */ | |
925 | void | |
926 | alpha_store_return_value (valtype, valbuf) | |
927 | struct type *valtype; | |
928 | char *valbuf; | |
929 | { | |
930 | int regnum; | |
931 | char raw_buffer[MAX_REGISTER_RAW_SIZE]; | |
932 | ||
933 | regnum = TYPE_CODE (valtype) == TYPE_CODE_FLT ? FP0_REGNUM : V0_REGNUM; | |
934 | memcpy(raw_buffer, valbuf, TYPE_LENGTH (valtype)); | |
935 | ||
936 | write_register_bytes(REGISTER_BYTE (regnum), raw_buffer, TYPE_LENGTH (valtype)); | |
937 | } | |
938 | ||
939 | /* Print the instruction at address MEMADDR in debugged memory, | |
940 | on STREAM. Returns length of the instruction, in bytes. */ | |
941 | ||
942 | int | |
943 | print_insn (memaddr, stream) | |
944 | CORE_ADDR memaddr; | |
945 | FILE *stream; | |
946 | { | |
947 | disassemble_info info; | |
948 | ||
949 | GDB_INIT_DISASSEMBLE_INFO(info, stream); | |
950 | ||
951 | return print_insn_alpha (memaddr, &info); | |
952 | } | |
953 | ||
954 | /* Just like reinit_frame_cache, but with the right arguments to be | |
955 | callable as an sfunc. */ | |
956 | static void | |
957 | reinit_frame_cache_sfunc (args, from_tty, c) | |
958 | char *args; | |
959 | int from_tty; | |
960 | struct cmd_list_element *c; | |
961 | { | |
962 | reinit_frame_cache (); | |
963 | } | |
964 | ||
965 | void | |
966 | _initialize_alpha_tdep () | |
967 | { | |
968 | struct cmd_list_element *c; | |
969 | ||
970 | /* Let the user set the fence post for heuristic_proc_start. */ | |
971 | ||
972 | /* We really would like to have both "0" and "unlimited" work, but | |
973 | command.c doesn't deal with that. So make it a var_zinteger | |
974 | because the user can always use "999999" or some such for unlimited. */ | |
975 | c = add_set_cmd ("heuristic-fence-post", class_support, var_zinteger, | |
976 | (char *) &heuristic_fence_post, | |
977 | "\ | |
978 | Set the distance searched for the start of a function.\n\ | |
979 | If you are debugging a stripped executable, GDB needs to search through the\n\ | |
980 | program for the start of a function. This command sets the distance of the\n\ | |
981 | search. The only need to set it is when debugging a stripped executable.", | |
982 | &setlist); | |
983 | /* We need to throw away the frame cache when we set this, since it | |
984 | might change our ability to get backtraces. */ | |
985 | c->function.sfunc = reinit_frame_cache_sfunc; | |
986 | add_show_from_set (c, &showlist); | |
987 | } |