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, 2009, 2010 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 #include "trad-frame.h"
  30
  31 #include "alpha-tdep.h"
  32 #include "mdebugread.h"
  33
  34 /* FIXME: Some of this code should perhaps be merged with mips.  */
  35
  36 /* *INDENT-OFF* */
  37 /* Layout of a stack frame on the alpha:
  38
  39                 |                               |
  40  pdr members:   |  7th ... nth arg,             |
  41                 |  `pushed' by caller.          |
  42                 |                               |
  43 ----------------|-------------------------------|<--  old_sp == vfp
  44    ^  ^  ^  ^   |                               |
  45    |  |  |  |   |                               |
  46    |  |localoff |  Copies of 1st .. 6th         |
  47    |  |  |  |   |  argument if necessary.       |
  48    |  |  |  v   |                               |
  49    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  50    |  |  |      |                               |
  51    |  |  |      |  Locals and temporaries.      |
  52    |  |  |      |                               |
  53    |  |  |      |-------------------------------|
  54    |  |  |      |                               |
  55    |-fregoffset |  Saved float registers.       |
  56    |  |  |      |  F9                           |
  57    |  |  |      |   .                           |
  58    |  |  |      |   .                           |
  59    |  |  |      |  F2                           |
  60    |  |  v      |                               |
  61    |  |  -------|-------------------------------|
  62    |  |         |                               |
  63    |  |         |  Saved registers.             |
  64    |  |         |  S6                           |
  65    |-regoffset  |   .                           |
  66    |  |         |   .                           |
  67    |  |         |  S0                           |
  68    |  |         |  pdr.pcreg                    |
  69    |  v         |                               |
  70    |  ----------|-------------------------------|
  71    |            |                               |
  72  frameoffset    |  Argument build area, gets    |
  73    |            |  7th ... nth arg for any      |
  74    |            |  called procedure.            |
  75    v            |                               |
  76    -------------|-------------------------------|<-- sp
  77                 |                               |
  78 */
  79 /* *INDENT-ON* */
  80
  81 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  82 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  83 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  84 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  85 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  86 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  87 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  88 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  89 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  90 \f
  91 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  92    be found; you'll have to fall back to other methods in that case.  */
  93
  94 static struct mdebug_extra_func_info *
  95 find_proc_desc (CORE_ADDR pc)
  96 {
  97   struct block *b = block_for_pc (pc);
  98   struct mdebug_extra_func_info *proc_desc = NULL;
  99   struct symbol *sym = NULL;
 100   char *sh_name = NULL;
 101
 102   if (b)
 103     {
 104       CORE_ADDR startaddr;
 105       find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
 106
 107       if (startaddr > BLOCK_START (b))
 108         /* This is the "pathological" case referred to in a comment in
 109            print_frame_info.  It might be better to move this check into
 110            symbol reading.  */
 111         sym = NULL;
 112       else
 113         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN, 0);
 114     }
 115
 116   if (sym)
 117     {
 118       proc_desc = (struct mdebug_extra_func_info *) SYMBOL_VALUE_BYTES (sym);
 119
 120       /* Correct incorrect setjmp procedure descriptor from the library
 121          to make backtrace through setjmp work.  */
 122       if (proc_desc->pdr.pcreg == 0
 123           && strcmp (sh_name, "setjmp") == 0)
 124         {
 125           proc_desc->pdr.pcreg = ALPHA_RA_REGNUM;
 126           proc_desc->pdr.regmask = 0x80000000;
 127           proc_desc->pdr.regoffset = -4;
 128         }
 129
 130       /* If we never found a PDR for this function in symbol reading,
 131          then examine prologues to find the information.  */
 132       if (proc_desc->pdr.framereg == -1)
 133         proc_desc = NULL;
 134     }
 135
 136   return proc_desc;
 137 }
 138
 139 /* Return a non-zero result if the function is frameless; zero otherwise.  */
 140
 141 static int
 142 alpha_mdebug_frameless (struct mdebug_extra_func_info *proc_desc)
 143 {
 144   return (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 145           && PROC_FRAME_OFFSET (proc_desc) == 0);
 146 }
 147
 148 /* This returns the PC of the first inst after the prologue.  If we can't
 149    find the prologue, then return 0.  */
 150
 151 static CORE_ADDR
 152 alpha_mdebug_after_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 153 {
 154   if (proc_desc)
 155     {
 156       /* If function is frameless, then we need to do it the hard way.  I
 157          strongly suspect that frameless always means prologueless... */
 158       if (alpha_mdebug_frameless (proc_desc))
 159         return 0;
 160     }
 161
 162   return alpha_after_prologue (pc);
 163 }
 164
 165 /* Return non-zero if we *might* be in a function prologue.  Return zero
 166    if we are definitively *not* in a function prologue.  */
 167
 168 static int
 169 alpha_mdebug_in_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 170 {
 171   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 172   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 173 }
 174
 175 \f
 176 /* Frame unwinder that reads mdebug PDRs.  */
 177
 178 struct alpha_mdebug_unwind_cache
 179 {
 180   struct mdebug_extra_func_info *proc_desc;
 181   CORE_ADDR vfp;
 182   struct trad_frame_saved_reg *saved_regs;
 183 };
 184
 185 /* Extract all of the information about the frame from PROC_DESC
 186    and store the resulting register save locations in the structure.  */
 187
 188 static struct alpha_mdebug_unwind_cache *
 189 alpha_mdebug_frame_unwind_cache (struct frame_info *this_frame,
 190                                  void **this_prologue_cache)
 191 {
 192   struct alpha_mdebug_unwind_cache *info;
 193   struct mdebug_extra_func_info *proc_desc;
 194   ULONGEST vfp;
 195   CORE_ADDR pc, reg_position;
 196   unsigned long mask;
 197   int ireg, returnreg;
 198
 199   if (*this_prologue_cache)
 200     return *this_prologue_cache;
 201
 202   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 203   *this_prologue_cache = info;
 204   pc = get_frame_address_in_block (this_frame);
 205
 206   /* ??? We don't seem to be able to cache the lookup of the PDR
 207      from alpha_mdebug_frame_p.  It'd be nice if we could change
 208      the arguments to that function.  Oh well.  */
 209   proc_desc = find_proc_desc (pc);
 210   info->proc_desc = proc_desc;
 211   gdb_assert (proc_desc != NULL);
 212
 213   info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 214
 215   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 216   vfp = get_frame_register_unsigned (this_frame, PROC_FRAME_REG (proc_desc));
 217   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 218   info->vfp = vfp;
 219
 220   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 221
 222   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 223   mask = PROC_REG_MASK (proc_desc);
 224   returnreg = PROC_PC_REG (proc_desc);
 225
 226   /* Note that RA is always saved first, regardless of its actual
 227      register number.  */
 228   if (mask & (1 << returnreg))
 229     {
 230       /* Clear bit for RA so we don't save it again later. */
 231       mask &= ~(1 << returnreg);
 232
 233       info->saved_regs[returnreg].addr = reg_position;
 234       reg_position += 8;
 235     }
 236
 237   for (ireg = 0; ireg <= 31; ++ireg)
 238     if (mask & (1 << ireg))
 239       {
 240         info->saved_regs[ireg].addr = reg_position;
 241         reg_position += 8;
 242       }
 243
 244   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 245   mask = PROC_FREG_MASK (proc_desc);
 246
 247   for (ireg = 0; ireg <= 31; ++ireg)
 248     if (mask & (1 << ireg))
 249       {
 250         info->saved_regs[ALPHA_FP0_REGNUM + ireg].addr = reg_position;
 251         reg_position += 8;
 252       }
 253
 254   /* The stack pointer of the previous frame is computed by popping
 255      the current stack frame.  */
 256   if (!trad_frame_addr_p (info->saved_regs, ALPHA_SP_REGNUM))
 257    trad_frame_set_value (info->saved_regs, ALPHA_SP_REGNUM, vfp);
 258
 259   return info;
 260 }
 261
 262 /* Given a GDB frame, determine the address of the calling function's
 263    frame.  This will be used to create a new GDB frame struct.  */
 264
 265 static void
 266 alpha_mdebug_frame_this_id (struct frame_info *this_frame,
 267                             void **this_prologue_cache,
 268                             struct frame_id *this_id)
 269 {
 270   struct alpha_mdebug_unwind_cache *info
 271     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 272
 273   *this_id = frame_id_build (info->vfp, get_frame_func (this_frame));
 274 }
 275
 276 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 277
 278 static struct value *
 279 alpha_mdebug_frame_prev_register (struct frame_info *this_frame,
 280                                   void **this_prologue_cache, int regnum)
 281 {
 282   struct alpha_mdebug_unwind_cache *info
 283     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 284
 285   /* The PC of the previous frame is stored in the link register of
 286      the current frame.  Frob regnum so that we pull the value from
 287      the correct place.  */
 288   if (regnum == ALPHA_PC_REGNUM)
 289     regnum = PROC_PC_REG (info->proc_desc);
 290
 291   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 292 }
 293
 294 /* Return a non-zero result if the size of the stack frame exceeds the
 295    maximum debuggable frame size (512 Kbytes); zero otherwise.  */
 296
 297 static int
 298 alpha_mdebug_max_frame_size_exceeded (struct mdebug_extra_func_info *proc_desc)
 299 {
 300   /* If frame offset is null, we can be in two cases: either the
 301      function is frameless (the stack frame is null) or its
 302      frame exceeds the maximum debuggable frame size (512 Kbytes).  */
 303
 304   return (PROC_FRAME_OFFSET (proc_desc) == 0
 305           && !alpha_mdebug_frameless (proc_desc));
 306 }
 307
 308 static int
 309 alpha_mdebug_frame_sniffer (const struct frame_unwind *self,
 310                             struct frame_info *this_frame,
 311                             void **this_cache)
 312 {
 313   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 314   struct mdebug_extra_func_info *proc_desc;
 315
 316   /* If this PC does not map to a PDR, then clearly this isn't an
 317      mdebug frame.  */
 318   proc_desc = find_proc_desc (pc);
 319   if (proc_desc == NULL)
 320     return 0;
 321
 322   /* If we're in the prologue, the PDR for this frame is not yet valid.
 323      Say no here and we'll fall back on the heuristic unwinder.  */
 324   if (alpha_mdebug_in_prologue (pc, proc_desc))
 325     return 0;
 326
 327   /* If the maximum debuggable frame size has been exceeded, the
 328      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 329   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 330     return 0;
 331
 332   return 1;
 333 }
 334
 335 static const struct frame_unwind alpha_mdebug_frame_unwind = {
 336   NORMAL_FRAME,
 337   alpha_mdebug_frame_this_id,
 338   alpha_mdebug_frame_prev_register,
 339   NULL,
 340   alpha_mdebug_frame_sniffer
 341 };
 342
 343 static CORE_ADDR
 344 alpha_mdebug_frame_base_address (struct frame_info *this_frame,
 345                                  void **this_prologue_cache)
 346 {
 347   struct alpha_mdebug_unwind_cache *info
 348     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 349
 350   return info->vfp;
 351 }
 352
 353 static CORE_ADDR
 354 alpha_mdebug_frame_locals_address (struct frame_info *this_frame,
 355                                    void **this_prologue_cache)
 356 {
 357   struct alpha_mdebug_unwind_cache *info
 358     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 359
 360   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 361 }
 362
 363 static CORE_ADDR
 364 alpha_mdebug_frame_args_address (struct frame_info *this_frame,
 365                                  void **this_prologue_cache)
 366 {
 367   struct alpha_mdebug_unwind_cache *info
 368     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 369
 370   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 371 }
 372
 373 static const struct frame_base alpha_mdebug_frame_base = {
 374   &alpha_mdebug_frame_unwind,
 375   alpha_mdebug_frame_base_address,
 376   alpha_mdebug_frame_locals_address,
 377   alpha_mdebug_frame_args_address
 378 };
 379
 380 static const struct frame_base *
 381 alpha_mdebug_frame_base_sniffer (struct frame_info *this_frame)
 382 {
 383   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 384   struct mdebug_extra_func_info *proc_desc;
 385
 386   /* If this PC does not map to a PDR, then clearly this isn't an
 387      mdebug frame.  */
 388   proc_desc = find_proc_desc (pc);
 389   if (proc_desc == NULL)
 390     return NULL;
 391
 392   /* If the maximum debuggable frame size has been exceeded, the
 393      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 394   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 395     return 0;
 396
 397   return &alpha_mdebug_frame_base;
 398 }
 399
 400 \f
 401 void
 402 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 403 {
 404   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 405
 406   frame_unwind_append_unwinder (gdbarch, &alpha_mdebug_frame_unwind);
 407   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 408 }