| 1 | /* Code dealing with dummy stack frames, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, |
| 4 | 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free |
| 5 | Software Foundation, Inc. |
| 6 | |
| 7 | This file is part of GDB. |
| 8 | |
| 9 | This program is free software; you can redistribute it and/or modify |
| 10 | it under the terms of the GNU General Public License as published by |
| 11 | the Free Software Foundation; either version 2 of the License, or |
| 12 | (at your option) any later version. |
| 13 | |
| 14 | This program is distributed in the hope that it will be useful, |
| 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | GNU General Public License for more details. |
| 18 | |
| 19 | You should have received a copy of the GNU General Public License |
| 20 | along with this program; if not, write to the Free Software |
| 21 | Foundation, Inc., 59 Temple Place - Suite 330, |
| 22 | Boston, MA 02111-1307, USA. */ |
| 23 | |
| 24 | |
| 25 | #include "defs.h" |
| 26 | #include "dummy-frame.h" |
| 27 | #include "regcache.h" |
| 28 | #include "frame.h" |
| 29 | #include "inferior.h" |
| 30 | #include "gdb_assert.h" |
| 31 | #include "frame-unwind.h" |
| 32 | #include "command.h" |
| 33 | #include "gdbcmd.h" |
| 34 | |
| 35 | static void dummy_frame_this_id (struct frame_info *next_frame, |
| 36 | void **this_prologue_cache, |
| 37 | struct frame_id *this_id); |
| 38 | |
| 39 | static int pc_in_dummy_frame (CORE_ADDR pc); |
| 40 | |
| 41 | /* Dummy frame. This saves the processor state just prior to setting |
| 42 | up the inferior function call. Older targets save the registers |
| 43 | on the target stack (but that really slows down function calls). */ |
| 44 | |
| 45 | struct dummy_frame |
| 46 | { |
| 47 | struct dummy_frame *next; |
| 48 | |
| 49 | /* These values belong to the caller (the previous frame, the frame |
| 50 | that this unwinds back to). */ |
| 51 | CORE_ADDR pc; |
| 52 | CORE_ADDR fp; |
| 53 | CORE_ADDR sp; |
| 54 | CORE_ADDR top; |
| 55 | struct frame_id id; |
| 56 | struct regcache *regcache; |
| 57 | |
| 58 | /* Address range of the call dummy code. Look for PC in the range |
| 59 | [LO..HI) (after allowing for DECR_PC_AFTER_BREAK). */ |
| 60 | CORE_ADDR call_lo; |
| 61 | CORE_ADDR call_hi; |
| 62 | }; |
| 63 | |
| 64 | static struct dummy_frame *dummy_frame_stack = NULL; |
| 65 | |
| 66 | /* Function: find_dummy_frame(pc, fp, sp) |
| 67 | |
| 68 | Search the stack of dummy frames for one matching the given PC and |
| 69 | FP/SP. Unlike pc_in_dummy_frame(), this function doesn't need to |
| 70 | adjust for DECR_PC_AFTER_BREAK. This is because it is only legal |
| 71 | to call this function after the PC has been adjusted. */ |
| 72 | |
| 73 | static struct dummy_frame * |
| 74 | find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) |
| 75 | { |
| 76 | struct dummy_frame *dummyframe; |
| 77 | |
| 78 | for (dummyframe = dummy_frame_stack; dummyframe != NULL; |
| 79 | dummyframe = dummyframe->next) |
| 80 | { |
| 81 | /* Does the PC fall within the dummy frame's breakpoint |
| 82 | instruction. If not, discard this one. */ |
| 83 | if (!(pc >= dummyframe->call_lo && pc < dummyframe->call_hi)) |
| 84 | continue; |
| 85 | /* Does the FP match? */ |
| 86 | if (dummyframe->top != 0) |
| 87 | { |
| 88 | /* If the target architecture explicitly saved the |
| 89 | top-of-stack before the inferior function call, assume |
| 90 | that that same architecture will always pass in an FP |
| 91 | (frame base) value that eactly matches that saved TOS. |
| 92 | Don't check the saved SP and SP as they can lead to false |
| 93 | hits. */ |
| 94 | if (fp != dummyframe->top) |
| 95 | continue; |
| 96 | } |
| 97 | else |
| 98 | { |
| 99 | /* An older target that hasn't explicitly or implicitly |
| 100 | saved the dummy frame's top-of-stack. Try matching the |
| 101 | FP against the saved SP and FP. NOTE: If you're trying |
| 102 | to fix a problem with GDB not correctly finding a dummy |
| 103 | frame, check the comments that go with FRAME_ALIGN() and |
| 104 | UNWIND_DUMMY_ID(). */ |
| 105 | if (fp != dummyframe->fp && fp != dummyframe->sp) |
| 106 | continue; |
| 107 | } |
| 108 | /* The FP matches this dummy frame. */ |
| 109 | return dummyframe; |
| 110 | } |
| 111 | |
| 112 | return NULL; |
| 113 | } |
| 114 | |
| 115 | static struct regcache * |
| 116 | deprecated_find_dummy_frame_regcache (CORE_ADDR pc, CORE_ADDR fp) |
| 117 | { |
| 118 | struct dummy_frame *dummy = find_dummy_frame (pc, fp); |
| 119 | if (dummy != NULL) |
| 120 | return dummy->regcache; |
| 121 | else |
| 122 | return NULL; |
| 123 | } |
| 124 | |
| 125 | char * |
| 126 | deprecated_generic_find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) |
| 127 | { |
| 128 | struct regcache *regcache = deprecated_find_dummy_frame_regcache (pc, fp); |
| 129 | if (regcache == NULL) |
| 130 | return NULL; |
| 131 | return deprecated_grub_regcache_for_registers (regcache); |
| 132 | } |
| 133 | |
| 134 | /* Function: pc_in_call_dummy (pc, sp, fp) |
| 135 | |
| 136 | Return true if the PC falls in a dummy frame created by gdb for an |
| 137 | inferior call. The code below which allows DECR_PC_AFTER_BREAK is |
| 138 | for infrun.c, which may give the function a PC without that |
| 139 | subtracted out. */ |
| 140 | |
| 141 | int |
| 142 | deprecated_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR fp) |
| 143 | { |
| 144 | return pc_in_dummy_frame (pc); |
| 145 | } |
| 146 | |
| 147 | /* Return non-zero if the PC falls in a dummy frame. |
| 148 | |
| 149 | The code below which allows DECR_PC_AFTER_BREAK is for infrun.c, |
| 150 | which may give the function a PC without that subtracted out. |
| 151 | |
| 152 | FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can |
| 153 | figure out what the real PC (as in the resume address) is BEFORE |
| 154 | calling this function. */ |
| 155 | |
| 156 | static int |
| 157 | pc_in_dummy_frame (CORE_ADDR pc) |
| 158 | { |
| 159 | struct dummy_frame *dummyframe; |
| 160 | for (dummyframe = dummy_frame_stack; |
| 161 | dummyframe != NULL; |
| 162 | dummyframe = dummyframe->next) |
| 163 | { |
| 164 | if ((pc >= dummyframe->call_lo) |
| 165 | && (pc < dummyframe->call_hi + DECR_PC_AFTER_BREAK)) |
| 166 | return 1; |
| 167 | } |
| 168 | return 0; |
| 169 | } |
| 170 | |
| 171 | /* Function: read_register_dummy |
| 172 | Find a saved register from before GDB calls a function in the inferior */ |
| 173 | |
| 174 | CORE_ADDR |
| 175 | deprecated_read_register_dummy (CORE_ADDR pc, CORE_ADDR fp, int regno) |
| 176 | { |
| 177 | struct regcache *dummy_regs = deprecated_find_dummy_frame_regcache (pc, fp); |
| 178 | |
| 179 | if (dummy_regs) |
| 180 | { |
| 181 | /* NOTE: cagney/2002-08-12: Replaced a call to |
| 182 | regcache_raw_read_as_address() with a call to |
| 183 | regcache_cooked_read_unsigned(). The old, ...as_address |
| 184 | function was eventually calling extract_unsigned_integer (nee |
| 185 | extract_address) to unpack the registers value. The below is |
| 186 | doing an unsigned extract so that it is functionally |
| 187 | equivalent. The read needs to be cooked as, otherwise, it |
| 188 | will never correctly return the value of a register in the |
| 189 | [NUM_REGS .. NUM_REGS+NUM_PSEUDO_REGS) range. */ |
| 190 | ULONGEST val; |
| 191 | regcache_cooked_read_unsigned (dummy_regs, regno, &val); |
| 192 | return val; |
| 193 | } |
| 194 | else |
| 195 | return 0; |
| 196 | } |
| 197 | |
| 198 | /* Save all the registers on the dummy frame stack. Most ports save the |
| 199 | registers on the target stack. This results in lots of unnecessary memory |
| 200 | references, which are slow when debugging via a serial line. Instead, we |
| 201 | save all the registers internally, and never write them to the stack. The |
| 202 | registers get restored when the called function returns to the entry point, |
| 203 | where a breakpoint is laying in wait. */ |
| 204 | |
| 205 | void |
| 206 | generic_push_dummy_frame (void) |
| 207 | { |
| 208 | struct dummy_frame *dummy_frame; |
| 209 | CORE_ADDR fp = get_frame_base (get_current_frame ()); |
| 210 | |
| 211 | /* check to see if there are stale dummy frames, |
| 212 | perhaps left over from when a longjump took us out of a |
| 213 | function that was called by the debugger */ |
| 214 | |
| 215 | dummy_frame = dummy_frame_stack; |
| 216 | while (dummy_frame) |
| 217 | if (INNER_THAN (dummy_frame->fp, fp)) /* stale -- destroy! */ |
| 218 | { |
| 219 | dummy_frame_stack = dummy_frame->next; |
| 220 | regcache_xfree (dummy_frame->regcache); |
| 221 | xfree (dummy_frame); |
| 222 | dummy_frame = dummy_frame_stack; |
| 223 | } |
| 224 | else |
| 225 | dummy_frame = dummy_frame->next; |
| 226 | |
| 227 | dummy_frame = xmalloc (sizeof (struct dummy_frame)); |
| 228 | dummy_frame->regcache = regcache_xmalloc (current_gdbarch); |
| 229 | |
| 230 | dummy_frame->pc = read_pc (); |
| 231 | dummy_frame->sp = read_sp (); |
| 232 | dummy_frame->top = 0; |
| 233 | dummy_frame->fp = fp; |
| 234 | dummy_frame->id = get_frame_id (get_current_frame ()); |
| 235 | regcache_cpy (dummy_frame->regcache, current_regcache); |
| 236 | dummy_frame->next = dummy_frame_stack; |
| 237 | dummy_frame_stack = dummy_frame; |
| 238 | } |
| 239 | |
| 240 | void |
| 241 | generic_save_dummy_frame_tos (CORE_ADDR sp) |
| 242 | { |
| 243 | dummy_frame_stack->top = sp; |
| 244 | } |
| 245 | |
| 246 | /* Record the upper/lower bounds on the address of the call dummy. */ |
| 247 | |
| 248 | void |
| 249 | generic_save_call_dummy_addr (CORE_ADDR lo, CORE_ADDR hi) |
| 250 | { |
| 251 | dummy_frame_stack->call_lo = lo; |
| 252 | dummy_frame_stack->call_hi = hi; |
| 253 | } |
| 254 | |
| 255 | /* Discard the innermost dummy frame from the dummy frame stack |
| 256 | (passed in as a parameter). */ |
| 257 | |
| 258 | static void |
| 259 | discard_innermost_dummy (struct dummy_frame **stack) |
| 260 | { |
| 261 | struct dummy_frame *tbd = (*stack); |
| 262 | (*stack) = (*stack)->next; |
| 263 | regcache_xfree (tbd->regcache); |
| 264 | xfree (tbd); |
| 265 | } |
| 266 | |
| 267 | void |
| 268 | deprecated_pop_dummy_frame (void) |
| 269 | { |
| 270 | struct dummy_frame *dummy_frame = dummy_frame_stack; |
| 271 | |
| 272 | /* FIXME: what if the first frame isn't the right one, eg.. |
| 273 | because one call-by-hand function has done a longjmp into another one? */ |
| 274 | |
| 275 | if (!dummy_frame) |
| 276 | error ("Can't pop dummy frame!"); |
| 277 | regcache_cpy (current_regcache, dummy_frame->regcache); |
| 278 | flush_cached_frames (); |
| 279 | |
| 280 | discard_innermost_dummy (&dummy_frame_stack); |
| 281 | } |
| 282 | |
| 283 | /* Given a call-dummy dummy-frame, return the registers. Here the |
| 284 | register value is taken from the local copy of the register buffer. */ |
| 285 | |
| 286 | static void |
| 287 | dummy_frame_prev_register (struct frame_info *next_frame, |
| 288 | void **this_prologue_cache, |
| 289 | int regnum, int *optimized, |
| 290 | enum lval_type *lvalp, CORE_ADDR *addrp, |
| 291 | int *realnum, void *bufferp) |
| 292 | { |
| 293 | struct dummy_frame *dummy; |
| 294 | struct frame_id id; |
| 295 | |
| 296 | /* Call the ID method which, if at all possible, will set the |
| 297 | prologue cache. */ |
| 298 | dummy_frame_this_id (next_frame, this_prologue_cache, &id); |
| 299 | dummy = (*this_prologue_cache); |
| 300 | gdb_assert (dummy != NULL); |
| 301 | |
| 302 | /* Describe the register's location. Generic dummy frames always |
| 303 | have the register value in an ``expression''. */ |
| 304 | *optimized = 0; |
| 305 | *lvalp = not_lval; |
| 306 | *addrp = 0; |
| 307 | *realnum = -1; |
| 308 | |
| 309 | /* If needed, find and return the value of the register. */ |
| 310 | if (bufferp != NULL) |
| 311 | { |
| 312 | /* Return the actual value. */ |
| 313 | /* Use the regcache_cooked_read() method so that it, on the fly, |
| 314 | constructs either a raw or pseudo register from the raw |
| 315 | register cache. */ |
| 316 | regcache_cooked_read (dummy->regcache, regnum, bufferp); |
| 317 | } |
| 318 | } |
| 319 | |
| 320 | /* Assuming that THIS frame is a dummy (remember, the NEXT and not |
| 321 | THIS frame is passed in), return the ID of THIS frame. That ID is |
| 322 | determined by examining the NEXT frame's unwound registers using |
| 323 | the method unwind_dummy_id(). As a side effect, THIS dummy frame's |
| 324 | dummy cache is located and and saved in THIS_PROLOGUE_CACHE. */ |
| 325 | |
| 326 | static void |
| 327 | dummy_frame_this_id (struct frame_info *next_frame, |
| 328 | void **this_prologue_cache, |
| 329 | struct frame_id *this_id) |
| 330 | { |
| 331 | struct dummy_frame *dummy = (*this_prologue_cache); |
| 332 | if (dummy != NULL) |
| 333 | { |
| 334 | (*this_id) = dummy->id; |
| 335 | return; |
| 336 | } |
| 337 | /* When unwinding a normal frame, the stack structure is determined |
| 338 | by analyzing the frame's function's code (be it using brute force |
| 339 | prologue analysis, or the dwarf2 CFI). In the case of a dummy |
| 340 | frame, that simply isn't possible. The The PC is either the |
| 341 | program entry point, or some random address on the stack. Trying |
| 342 | to use that PC to apply standard frame ID unwind techniques is |
| 343 | just asking for trouble. */ |
| 344 | if (gdbarch_unwind_dummy_id_p (current_gdbarch)) |
| 345 | { |
| 346 | /* Use an architecture specific method to extract the prev's |
| 347 | dummy ID from the next frame. Note that this method uses |
| 348 | frame_register_unwind to obtain the register values needed to |
| 349 | determine the dummy frame's ID. */ |
| 350 | (*this_id) = gdbarch_unwind_dummy_id (current_gdbarch, next_frame); |
| 351 | } |
| 352 | else if (get_frame_type (next_frame) == SENTINEL_FRAME) |
| 353 | { |
| 354 | /* We're unwinding a sentinel frame, the PC of which is pointing |
| 355 | at a stack dummy. Fake up the dummy frame's ID using the |
| 356 | same sequence as is found a traditional unwinder. Once all |
| 357 | architectures supply the unwind_dummy_id method, this code |
| 358 | can go away. */ |
| 359 | (*this_id) = frame_id_build (deprecated_read_fp (), read_pc ()); |
| 360 | } |
| 361 | else if (legacy_frame_p (current_gdbarch) |
| 362 | && get_prev_frame (next_frame)) |
| 363 | { |
| 364 | /* Things are looking seriously grim! Assume that the legacy |
| 365 | get_prev_frame code has already created THIS frame and linked |
| 366 | it in to the frame chain (a pretty bold assumption), extract |
| 367 | the ID from THIS base / pc. */ |
| 368 | (*this_id) = frame_id_build (get_frame_base (get_prev_frame (next_frame)), |
| 369 | get_frame_pc (get_prev_frame (next_frame))); |
| 370 | } |
| 371 | else |
| 372 | { |
| 373 | /* Ouch! We're not trying to find the innermost frame's ID yet |
| 374 | we're trying to unwind to a dummy. The architecture must |
| 375 | provide the unwind_dummy_id() method. Abandon the unwind |
| 376 | process but only after first warning the user. */ |
| 377 | internal_warning (__FILE__, __LINE__, |
| 378 | "Missing unwind_dummy_id architecture method"); |
| 379 | (*this_id) = null_frame_id; |
| 380 | return; |
| 381 | } |
| 382 | (*this_prologue_cache) = find_dummy_frame ((*this_id).code_addr, |
| 383 | (*this_id).stack_addr); |
| 384 | } |
| 385 | |
| 386 | static struct frame_unwind dummy_frame_unwind = |
| 387 | { |
| 388 | DUMMY_FRAME, |
| 389 | dummy_frame_this_id, |
| 390 | dummy_frame_prev_register |
| 391 | }; |
| 392 | |
| 393 | const struct frame_unwind * |
| 394 | dummy_frame_sniffer (struct frame_info *next_frame) |
| 395 | { |
| 396 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 397 | if (pc_in_dummy_frame (pc)) |
| 398 | return &dummy_frame_unwind; |
| 399 | else |
| 400 | return NULL; |
| 401 | } |
| 402 | |
| 403 | static void |
| 404 | fprint_dummy_frames (struct ui_file *file) |
| 405 | { |
| 406 | struct dummy_frame *s; |
| 407 | for (s = dummy_frame_stack; s != NULL; s = s->next) |
| 408 | { |
| 409 | gdb_print_host_address (s, file); |
| 410 | fprintf_unfiltered (file, ":"); |
| 411 | fprintf_unfiltered (file, " pc=0x%s", paddr (s->pc)); |
| 412 | fprintf_unfiltered (file, " fp=0x%s", paddr (s->fp)); |
| 413 | fprintf_unfiltered (file, " sp=0x%s", paddr (s->sp)); |
| 414 | fprintf_unfiltered (file, " top=0x%s", paddr (s->top)); |
| 415 | fprintf_unfiltered (file, " id="); |
| 416 | fprint_frame_id (file, s->id); |
| 417 | fprintf_unfiltered (file, " call_lo=0x%s", paddr (s->call_lo)); |
| 418 | fprintf_unfiltered (file, " call_hi=0x%s", paddr (s->call_hi)); |
| 419 | fprintf_unfiltered (file, "\n"); |
| 420 | } |
| 421 | } |
| 422 | |
| 423 | static void |
| 424 | maintenance_print_dummy_frames (char *args, int from_tty) |
| 425 | { |
| 426 | if (args == NULL) |
| 427 | fprint_dummy_frames (gdb_stdout); |
| 428 | else |
| 429 | { |
| 430 | struct ui_file *file = gdb_fopen (args, "w"); |
| 431 | if (file == NULL) |
| 432 | perror_with_name ("maintenance print dummy-frames"); |
| 433 | fprint_dummy_frames (file); |
| 434 | ui_file_delete (file); |
| 435 | } |
| 436 | } |
| 437 | |
| 438 | extern void _initialize_dummy_frame (void); |
| 439 | |
| 440 | void |
| 441 | _initialize_dummy_frame (void) |
| 442 | { |
| 443 | add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, |
| 444 | "Print the contents of the internal dummy-frame stack.", |
| 445 | &maintenanceprintlist); |
| 446 | |
| 447 | } |