| 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 Free Software |
| 5 | 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 | |
| 32 | /* Dummy frame. This saves the processor state just prior to setting |
| 33 | up the inferior function call. Older targets save the registers |
| 34 | on the target stack (but that really slows down function calls). */ |
| 35 | |
| 36 | struct dummy_frame |
| 37 | { |
| 38 | struct dummy_frame *next; |
| 39 | |
| 40 | /* These values belong to the caller (the previous frame, the frame |
| 41 | that this unwinds back to). */ |
| 42 | CORE_ADDR pc; |
| 43 | CORE_ADDR fp; |
| 44 | CORE_ADDR sp; |
| 45 | CORE_ADDR top; |
| 46 | struct regcache *regcache; |
| 47 | |
| 48 | /* Address range of the call dummy code. Look for PC in the range |
| 49 | [LO..HI) (after allowing for DECR_PC_AFTER_BREAK). */ |
| 50 | CORE_ADDR call_lo; |
| 51 | CORE_ADDR call_hi; |
| 52 | }; |
| 53 | |
| 54 | static struct dummy_frame *dummy_frame_stack = NULL; |
| 55 | |
| 56 | /* Function: find_dummy_frame(pc, fp, sp) |
| 57 | |
| 58 | Search the stack of dummy frames for one matching the given PC and |
| 59 | FP/SP. Unlike pc_in_dummy_frame(), this function doesn't need to |
| 60 | adjust for DECR_PC_AFTER_BREAK. This is because it is only legal |
| 61 | to call this function after the PC has been adjusted. */ |
| 62 | |
| 63 | static struct dummy_frame * |
| 64 | find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) |
| 65 | { |
| 66 | struct dummy_frame *dummyframe; |
| 67 | |
| 68 | for (dummyframe = dummy_frame_stack; dummyframe != NULL; |
| 69 | dummyframe = dummyframe->next) |
| 70 | { |
| 71 | /* Does the PC fall within the dummy frame's breakpoint |
| 72 | instruction. If not, discard this one. */ |
| 73 | if (!(pc >= dummyframe->call_lo && pc < dummyframe->call_hi)) |
| 74 | continue; |
| 75 | /* Does the FP match? */ |
| 76 | if (dummyframe->top != 0) |
| 77 | { |
| 78 | /* If the target architecture explicitly saved the |
| 79 | top-of-stack before the inferior function call, assume |
| 80 | that that same architecture will always pass in an FP |
| 81 | (frame base) value that eactly matches that saved TOS. |
| 82 | Don't check the saved SP and SP as they can lead to false |
| 83 | hits. */ |
| 84 | if (fp != dummyframe->top) |
| 85 | continue; |
| 86 | } |
| 87 | else |
| 88 | { |
| 89 | /* An older target that hasn't explicitly or implicitly |
| 90 | saved the dummy frame's top-of-stack. Try matching the |
| 91 | FP against the saved SP and FP. NOTE: If you're trying |
| 92 | to fix a problem with GDB not correctly finding a dummy |
| 93 | frame, check the comments that go with FRAME_ALIGN() and |
| 94 | SAVE_DUMMY_FRAME_TOS(). */ |
| 95 | if (fp != dummyframe->fp && fp != dummyframe->sp) |
| 96 | continue; |
| 97 | } |
| 98 | /* The FP matches this dummy frame. */ |
| 99 | return dummyframe; |
| 100 | } |
| 101 | |
| 102 | return NULL; |
| 103 | } |
| 104 | |
| 105 | struct dummy_frame * |
| 106 | cached_find_dummy_frame (struct frame_info *frame, void **cache) |
| 107 | { |
| 108 | if ((*cache) == NULL) |
| 109 | (*cache) = find_dummy_frame (get_frame_pc (frame), get_frame_base (frame)); |
| 110 | return (*cache); |
| 111 | } |
| 112 | |
| 113 | struct regcache * |
| 114 | generic_find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) |
| 115 | { |
| 116 | struct dummy_frame *dummy = find_dummy_frame (pc, fp); |
| 117 | if (dummy != NULL) |
| 118 | return dummy->regcache; |
| 119 | else |
| 120 | return NULL; |
| 121 | } |
| 122 | |
| 123 | char * |
| 124 | deprecated_generic_find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) |
| 125 | { |
| 126 | struct regcache *regcache = generic_find_dummy_frame (pc, fp); |
| 127 | if (regcache == NULL) |
| 128 | return NULL; |
| 129 | return deprecated_grub_regcache_for_registers (regcache); |
| 130 | } |
| 131 | |
| 132 | /* Function: pc_in_call_dummy (pc, sp, fp) |
| 133 | |
| 134 | Return true if the PC falls in a dummy frame created by gdb for an |
| 135 | inferior call. The code below which allows DECR_PC_AFTER_BREAK is |
| 136 | for infrun.c, which may give the function a PC without that |
| 137 | subtracted out. */ |
| 138 | |
| 139 | int |
| 140 | generic_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR fp) |
| 141 | { |
| 142 | return pc_in_dummy_frame (pc); |
| 143 | } |
| 144 | |
| 145 | /* Return non-zero if the PC falls in a dummy frame. |
| 146 | |
| 147 | The code below which allows DECR_PC_AFTER_BREAK is for infrun.c, |
| 148 | which may give the function a PC without that subtracted out. |
| 149 | |
| 150 | FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can |
| 151 | figure out what the real PC (as in the resume address) is BEFORE |
| 152 | calling this function (Oh, and I'm not even sure that this function |
| 153 | is called with an decremented PC, the call to pc_in_call_dummy() in |
| 154 | that file is conditional on !CALL_DUMMY_BREAKPOINT_OFFSET_P yet |
| 155 | generic dummy targets set CALL_DUMMY_BREAKPOINT_OFFSET. True?). */ |
| 156 | |
| 157 | int |
| 158 | pc_in_dummy_frame (CORE_ADDR pc) |
| 159 | { |
| 160 | struct dummy_frame *dummyframe; |
| 161 | for (dummyframe = dummy_frame_stack; |
| 162 | dummyframe != NULL; |
| 163 | dummyframe = dummyframe->next) |
| 164 | { |
| 165 | if ((pc >= dummyframe->call_lo) |
| 166 | && (pc < dummyframe->call_hi + DECR_PC_AFTER_BREAK)) |
| 167 | return 1; |
| 168 | } |
| 169 | return 0; |
| 170 | } |
| 171 | |
| 172 | /* Function: read_register_dummy |
| 173 | Find a saved register from before GDB calls a function in the inferior */ |
| 174 | |
| 175 | CORE_ADDR |
| 176 | deprecated_read_register_dummy (CORE_ADDR pc, CORE_ADDR fp, int regno) |
| 177 | { |
| 178 | struct regcache *dummy_regs = generic_find_dummy_frame (pc, fp); |
| 179 | |
| 180 | if (dummy_regs) |
| 181 | { |
| 182 | /* NOTE: cagney/2002-08-12: Replaced a call to |
| 183 | regcache_raw_read_as_address() with a call to |
| 184 | regcache_cooked_read_unsigned(). The old, ...as_address |
| 185 | function was eventually calling extract_unsigned_integer (via |
| 186 | extract_address) to unpack the registers value. The below is |
| 187 | doing an unsigned extract so that it is functionally |
| 188 | equivalent. The read needs to be cooked as, otherwise, it |
| 189 | will never correctly return the value of a register in the |
| 190 | [NUM_REGS .. NUM_REGS+NUM_PSEUDO_REGS) range. */ |
| 191 | ULONGEST val; |
| 192 | regcache_cooked_read_unsigned (dummy_regs, regno, &val); |
| 193 | return val; |
| 194 | } |
| 195 | else |
| 196 | return 0; |
| 197 | } |
| 198 | |
| 199 | /* Save all the registers on the dummy frame stack. Most ports save the |
| 200 | registers on the target stack. This results in lots of unnecessary memory |
| 201 | references, which are slow when debugging via a serial line. Instead, we |
| 202 | save all the registers internally, and never write them to the stack. The |
| 203 | registers get restored when the called function returns to the entry point, |
| 204 | where a breakpoint is laying in wait. */ |
| 205 | |
| 206 | void |
| 207 | generic_push_dummy_frame (void) |
| 208 | { |
| 209 | struct dummy_frame *dummy_frame; |
| 210 | CORE_ADDR fp = get_frame_base (get_current_frame ()); |
| 211 | |
| 212 | /* check to see if there are stale dummy frames, |
| 213 | perhaps left over from when a longjump took us out of a |
| 214 | function that was called by the debugger */ |
| 215 | |
| 216 | dummy_frame = dummy_frame_stack; |
| 217 | while (dummy_frame) |
| 218 | if (INNER_THAN (dummy_frame->fp, fp)) /* stale -- destroy! */ |
| 219 | { |
| 220 | dummy_frame_stack = dummy_frame->next; |
| 221 | regcache_xfree (dummy_frame->regcache); |
| 222 | xfree (dummy_frame); |
| 223 | dummy_frame = dummy_frame_stack; |
| 224 | } |
| 225 | else |
| 226 | dummy_frame = dummy_frame->next; |
| 227 | |
| 228 | dummy_frame = xmalloc (sizeof (struct dummy_frame)); |
| 229 | dummy_frame->regcache = regcache_xmalloc (current_gdbarch); |
| 230 | |
| 231 | dummy_frame->pc = read_pc (); |
| 232 | dummy_frame->sp = read_sp (); |
| 233 | dummy_frame->top = 0; |
| 234 | dummy_frame->fp = fp; |
| 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 | /* Restore the machine state from either the saved dummy stack or a |
| 256 | real stack frame. */ |
| 257 | |
| 258 | void |
| 259 | generic_pop_current_frame (void (*popper) (struct frame_info * frame)) |
| 260 | { |
| 261 | struct frame_info *frame = get_current_frame (); |
| 262 | if (get_frame_type (frame) == DUMMY_FRAME) |
| 263 | /* NOTE: cagney/2002-22-23: Does this ever occure? Surely a dummy |
| 264 | frame will have already been poped by the "infrun.c" code. */ |
| 265 | generic_pop_dummy_frame (); |
| 266 | else |
| 267 | (*popper) (frame); |
| 268 | } |
| 269 | |
| 270 | /* Function: pop_dummy_frame |
| 271 | Restore the machine state from a saved dummy stack frame. */ |
| 272 | |
| 273 | void |
| 274 | generic_pop_dummy_frame (void) |
| 275 | { |
| 276 | struct dummy_frame *dummy_frame = dummy_frame_stack; |
| 277 | |
| 278 | /* FIXME: what if the first frame isn't the right one, eg.. |
| 279 | because one call-by-hand function has done a longjmp into another one? */ |
| 280 | |
| 281 | if (!dummy_frame) |
| 282 | error ("Can't pop dummy frame!"); |
| 283 | dummy_frame_stack = dummy_frame->next; |
| 284 | regcache_cpy (current_regcache, dummy_frame->regcache); |
| 285 | flush_cached_frames (); |
| 286 | |
| 287 | regcache_xfree (dummy_frame->regcache); |
| 288 | xfree (dummy_frame); |
| 289 | } |
| 290 | |
| 291 | /* Function: fix_call_dummy |
| 292 | Stub function. Generic dummy frames typically do not need to fix |
| 293 | the frame being created */ |
| 294 | |
| 295 | void |
| 296 | generic_fix_call_dummy (char *dummy, CORE_ADDR pc, CORE_ADDR fun, int nargs, |
| 297 | struct value **args, struct type *type, int gcc_p) |
| 298 | { |
| 299 | return; |
| 300 | } |
| 301 | |
| 302 | /* Given a call-dummy dummy-frame, return the registers. Here the |
| 303 | register value is taken from the local copy of the register buffer. */ |
| 304 | |
| 305 | void |
| 306 | dummy_frame_register_unwind (struct frame_info *frame, void **cache, |
| 307 | int regnum, int *optimized, |
| 308 | enum lval_type *lvalp, CORE_ADDR *addrp, |
| 309 | int *realnum, void *bufferp) |
| 310 | { |
| 311 | struct dummy_frame *dummy = cached_find_dummy_frame (frame, cache); |
| 312 | gdb_assert (dummy != NULL); |
| 313 | |
| 314 | /* Describe the register's location. Generic dummy frames always |
| 315 | have the register value in an ``expression''. */ |
| 316 | *optimized = 0; |
| 317 | *lvalp = not_lval; |
| 318 | *addrp = 0; |
| 319 | *realnum = -1; |
| 320 | |
| 321 | /* If needed, find and return the value of the register. */ |
| 322 | if (bufferp != NULL) |
| 323 | { |
| 324 | /* Return the actual value. */ |
| 325 | /* Use the regcache_cooked_read() method so that it, on the fly, |
| 326 | constructs either a raw or pseudo register from the raw |
| 327 | register cache. */ |
| 328 | regcache_cooked_read (dummy->regcache, regnum, bufferp); |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | CORE_ADDR |
| 333 | dummy_frame_pc_unwind (struct frame_info *frame, |
| 334 | void **cache) |
| 335 | { |
| 336 | struct dummy_frame *dummy = cached_find_dummy_frame (frame, cache); |
| 337 | /* Oops! In a dummy-frame but can't find the stack dummy. Pretend |
| 338 | that the frame doesn't unwind. Should this function instead |
| 339 | return a has-no-caller indication? */ |
| 340 | if (dummy == NULL) |
| 341 | return 0; |
| 342 | return dummy->pc; |
| 343 | } |
| 344 | |