gdb/alpha-mdebug-tdep.c

   1 /* Target-dependent mdebug code for the ALPHA architecture.
   2    Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   3    2003, 2007, 2008 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "frame-unwind.h"
  23 #include "frame-base.h"
  24 #include "symtab.h"
  25 #include "gdbcore.h"
  26 #include "block.h"
  27 #include "gdb_assert.h"
  28 #include "gdb_string.h"
  29
  30 #include "alpha-tdep.h"
  31 #include "mdebugread.h"
  32
  33 /* FIXME: Some of this code should perhaps be merged with mips.  */
  34
  35 /* *INDENT-OFF* */
  36 /* Layout of a stack frame on the alpha:
  37
  38                 |                               |
  39  pdr members:   |  7th ... nth arg,             |
  40                 |  `pushed' by caller.          |
  41                 |                               |
  42 ----------------|-------------------------------|<--  old_sp == vfp
  43    ^  ^  ^  ^   |                               |
  44    |  |  |  |   |                               |
  45    |  |localoff |  Copies of 1st .. 6th         |
  46    |  |  |  |   |  argument if necessary.       |
  47    |  |  |  v   |                               |
  48    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  49    |  |  |      |                               |
  50    |  |  |      |  Locals and temporaries.      |
  51    |  |  |      |                               |
  52    |  |  |      |-------------------------------|
  53    |  |  |      |                               |
  54    |-fregoffset |  Saved float registers.       |
  55    |  |  |      |  F9                           |
  56    |  |  |      |   .                           |
  57    |  |  |      |   .                           |
  58    |  |  |      |  F2                           |
  59    |  |  v      |                               |
  60    |  |  -------|-------------------------------|
  61    |  |         |                               |
  62    |  |         |  Saved registers.             |
  63    |  |         |  S6                           |
  64    |-regoffset  |   .                           |
  65    |  |         |   .                           |
  66    |  |         |  S0                           |
  67    |  |         |  pdr.pcreg                    |
  68    |  v         |                               |
  69    |  ----------|-------------------------------|
  70    |            |                               |
  71  frameoffset    |  Argument build area, gets    |
  72    |            |  7th ... nth arg for any      |
  73    |            |  called procedure.            |
  74    v            |                               |
  75    -------------|-------------------------------|<-- sp
  76                 |                               |
  77 */
  78 /* *INDENT-ON* */
  79
  80 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  81 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  82 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  83 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  84 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  85 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  86 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  87 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  88 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  89 \f
  90 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  91    be found; you'll have to fall back to other methods in that case.  */
  92
  93 static struct mdebug_extra_func_info *
  94 find_proc_desc (CORE_ADDR pc)
  95 {
  96   struct block *b = block_for_pc (pc);
  97   struct mdebug_extra_func_info *proc_desc = NULL;
  98   struct symbol *sym = NULL;
  99   char *sh_name = NULL;
 100
 101   if (b)
 102     {
 103       CORE_ADDR startaddr;
 104       find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
 105
 106       if (startaddr > BLOCK_START (b))
 107         /* This is the "pathological" case referred to in a comment in
 108            print_frame_info.  It might be better to move this check into
 109            symbol reading.  */
 110         sym = NULL;
 111       else
 112         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN, 0, NULL);
 113     }
 114
 115   if (sym)
 116     {
 117       proc_desc = (struct mdebug_extra_func_info *) SYMBOL_VALUE (sym);
 118
 119       /* Correct incorrect setjmp procedure descriptor from the library
 120          to make backtrace through setjmp work.  */
 121       if (proc_desc->pdr.pcreg == 0
 122           && strcmp (sh_name, "setjmp") == 0)
 123         {
 124           proc_desc->pdr.pcreg = ALPHA_RA_REGNUM;
 125           proc_desc->pdr.regmask = 0x80000000;
 126           proc_desc->pdr.regoffset = -4;
 127         }
 128
 129       /* If we never found a PDR for this function in symbol reading,
 130          then examine prologues to find the information.  */
 131       if (proc_desc->pdr.framereg == -1)
 132         proc_desc = NULL;
 133     }
 134
 135   return proc_desc;
 136 }
 137
 138 /* This returns the PC of the first inst after the prologue.  If we can't
 139    find the prologue, then return 0.  */
 140
 141 static CORE_ADDR
 142 alpha_mdebug_after_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 143 {
 144   if (proc_desc)
 145     {
 146       /* If function is frameless, then we need to do it the hard way.  I
 147          strongly suspect that frameless always means prologueless... */
 148       if (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 149           && PROC_FRAME_OFFSET (proc_desc) == 0)
 150         return 0;
 151     }
 152
 153   return alpha_after_prologue (pc);
 154 }
 155
 156 /* Return non-zero if we *might* be in a function prologue.  Return zero
 157    if we are definitively *not* in a function prologue.  */
 158
 159 static int
 160 alpha_mdebug_in_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 161 {
 162   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 163   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 164 }
 165
 166 \f
 167 /* Frame unwinder that reads mdebug PDRs.  */
 168
 169 struct alpha_mdebug_unwind_cache
 170 {
 171   struct mdebug_extra_func_info *proc_desc;
 172   CORE_ADDR vfp;
 173   CORE_ADDR *saved_regs;
 174 };
 175
 176 /* Extract all of the information about the frame from PROC_DESC
 177    and store the resulting register save locations in the structure.  */
 178
 179 static struct alpha_mdebug_unwind_cache *
 180 alpha_mdebug_frame_unwind_cache (struct frame_info *next_frame,
 181                                  void **this_prologue_cache)
 182 {
 183   struct alpha_mdebug_unwind_cache *info;
 184   struct mdebug_extra_func_info *proc_desc;
 185   ULONGEST vfp;
 186   CORE_ADDR pc, reg_position;
 187   unsigned long mask;
 188   int ireg, returnreg;
 189
 190   if (*this_prologue_cache)
 191     return *this_prologue_cache;
 192
 193   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 194   *this_prologue_cache = info;
 195   pc = frame_pc_unwind (next_frame);
 196
 197   /* ??? We don't seem to be able to cache the lookup of the PDR
 198      from alpha_mdebug_frame_p.  It'd be nice if we could change
 199      the arguments to that function.  Oh well.  */
 200   proc_desc = find_proc_desc (pc);
 201   info->proc_desc = proc_desc;
 202   gdb_assert (proc_desc != NULL);
 203
 204   info->saved_regs = frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
 205
 206   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 207   vfp = frame_unwind_register_unsigned (next_frame, PROC_FRAME_REG (proc_desc));
 208   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 209   info->vfp = vfp;
 210
 211   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 212
 213   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 214   mask = PROC_REG_MASK (proc_desc);
 215   returnreg = PROC_PC_REG (proc_desc);
 216
 217   /* Note that RA is always saved first, regardless of its actual
 218      register number.  */
 219   if (mask & (1 << returnreg))
 220     {
 221       /* Clear bit for RA so we don't save it again later. */
 222       mask &= ~(1 << returnreg);
 223
 224       info->saved_regs[returnreg] = reg_position;
 225       reg_position += 8;
 226     }
 227
 228   for (ireg = 0; ireg <= 31; ++ireg)
 229     if (mask & (1 << ireg))
 230       {
 231         info->saved_regs[ireg] = reg_position;
 232         reg_position += 8;
 233       }
 234
 235   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 236   mask = PROC_FREG_MASK (proc_desc);
 237
 238   for (ireg = 0; ireg <= 31; ++ireg)
 239     if (mask & (1 << ireg))
 240       {
 241         info->saved_regs[ALPHA_FP0_REGNUM + ireg] = reg_position;
 242         reg_position += 8;
 243       }
 244
 245   return info;
 246 }
 247
 248 /* Given a GDB frame, determine the address of the calling function's
 249    frame.  This will be used to create a new GDB frame struct.  */
 250
 251 static void
 252 alpha_mdebug_frame_this_id (struct frame_info *next_frame,
 253                             void **this_prologue_cache,
 254                             struct frame_id *this_id)
 255 {
 256   struct alpha_mdebug_unwind_cache *info
 257     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 258
 259   *this_id = frame_id_build (info->vfp,
 260                              frame_func_unwind (next_frame, NORMAL_FRAME));
 261 }
 262
 263 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 264
 265 static void
 266 alpha_mdebug_frame_prev_register (struct frame_info *next_frame,
 267                                   void **this_prologue_cache,
 268                                   int regnum, int *optimizedp,
 269                                   enum lval_type *lvalp, CORE_ADDR *addrp,
 270                                   int *realnump, gdb_byte *bufferp)
 271 {
 272   struct alpha_mdebug_unwind_cache *info
 273     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 274
 275   /* The PC of the previous frame is stored in the link register of
 276      the current frame.  Frob regnum so that we pull the value from
 277      the correct place.  */
 278   if (regnum == ALPHA_PC_REGNUM)
 279     regnum = PROC_PC_REG (info->proc_desc);
 280
 281   /* For all registers known to be saved in the current frame,
 282      do the obvious and pull the value out.  */
 283   if (info->saved_regs[regnum])
 284     {
 285       *optimizedp = 0;
 286       *lvalp = lval_memory;
 287       *addrp = info->saved_regs[regnum];
 288       *realnump = -1;
 289       if (bufferp != NULL)
 290         get_frame_memory (next_frame, *addrp, bufferp, ALPHA_REGISTER_SIZE);
 291       return;
 292     }
 293
 294   /* The stack pointer of the previous frame is computed by popping
 295      the current stack frame.  */
 296   if (regnum == ALPHA_SP_REGNUM)
 297     {
 298       *optimizedp = 0;
 299       *lvalp = not_lval;
 300       *addrp = 0;
 301       *realnump = -1;
 302       if (bufferp != NULL)
 303         store_unsigned_integer (bufferp, ALPHA_REGISTER_SIZE, info->vfp);
 304       return;
 305     }
 306
 307   /* Otherwise assume the next frame has the same register value.  */
 308   *optimizedp = 0;
 309   *lvalp = lval_register;
 310   *addrp = 0;
 311   *realnump = regnum;
 312   if (bufferp)
 313     frame_unwind_register (next_frame, *realnump, bufferp);
 314 }
 315
 316 static const struct frame_unwind alpha_mdebug_frame_unwind = {
 317   NORMAL_FRAME,
 318   alpha_mdebug_frame_this_id,
 319   alpha_mdebug_frame_prev_register
 320 };
 321
 322 const struct frame_unwind *
 323 alpha_mdebug_frame_sniffer (struct frame_info *next_frame)
 324 {
 325   CORE_ADDR pc = frame_unwind_address_in_block (next_frame, NORMAL_FRAME);
 326   struct mdebug_extra_func_info *proc_desc;
 327
 328   /* If this PC does not map to a PDR, then clearly this isn't an
 329      mdebug frame.  */
 330   proc_desc = find_proc_desc (pc);
 331   if (proc_desc == NULL)
 332     return NULL;
 333
 334   /* If we're in the prologue, the PDR for this frame is not yet valid.
 335      Say no here and we'll fall back on the heuristic unwinder.  */
 336   if (alpha_mdebug_in_prologue (pc, proc_desc))
 337     return NULL;
 338
 339   return &alpha_mdebug_frame_unwind;
 340 }
 341
 342 static CORE_ADDR
 343 alpha_mdebug_frame_base_address (struct frame_info *next_frame,
 344                                  void **this_prologue_cache)
 345 {
 346   struct alpha_mdebug_unwind_cache *info
 347     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 348
 349   return info->vfp;
 350 }
 351
 352 static CORE_ADDR
 353 alpha_mdebug_frame_locals_address (struct frame_info *next_frame,
 354                                    void **this_prologue_cache)
 355 {
 356   struct alpha_mdebug_unwind_cache *info
 357     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 358
 359   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 360 }
 361
 362 static CORE_ADDR
 363 alpha_mdebug_frame_args_address (struct frame_info *next_frame,
 364                                  void **this_prologue_cache)
 365 {
 366   struct alpha_mdebug_unwind_cache *info
 367     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 368
 369   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 370 }
 371
 372 static const struct frame_base alpha_mdebug_frame_base = {
 373   &alpha_mdebug_frame_unwind,
 374   alpha_mdebug_frame_base_address,
 375   alpha_mdebug_frame_locals_address,
 376   alpha_mdebug_frame_args_address
 377 };
 378
 379 static const struct frame_base *
 380 alpha_mdebug_frame_base_sniffer (struct frame_info *next_frame)
 381 {
 382   CORE_ADDR pc = frame_unwind_address_in_block (next_frame, NORMAL_FRAME);
 383   struct mdebug_extra_func_info *proc_desc;
 384
 385   /* If this PC does not map to a PDR, then clearly this isn't an
 386      mdebug frame.  */
 387   proc_desc = find_proc_desc (pc);
 388   if (proc_desc == NULL)
 389     return NULL;
 390
 391   return &alpha_mdebug_frame_base;
 392 }
 393
 394 \f
 395 void
 396 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 397 {
 398   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 399
 400   frame_unwind_append_sniffer (gdbarch, alpha_mdebug_frame_sniffer);
 401   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 402 }