gdb/alpha-mdebug-tdep.c

   1 /* Target-dependent mdebug code for the ALPHA architecture.
   2    Copyright (C) 1993-2023 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 3 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, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include "defs.h"
  20 #include "frame.h"
  21 #include "frame-unwind.h"
  22 #include "frame-base.h"
  23 #include "symtab.h"
  24 #include "gdbcore.h"
  25 #include "block.h"
  26 #include "trad-frame.h"
  27
  28 #include "alpha-tdep.h"
  29 #include "mdebugread.h"
  30 #include "gdbarch.h"
  31
  32 /* FIXME: Some of this code should perhaps be merged with mips.  */
  33
  34 /* Layout of a stack frame on the alpha:
  35
  36                 |                               |
  37  pdr members:   |  7th ... nth arg,             |
  38                 |  `pushed' by caller.          |
  39                 |                               |
  40 ----------------|-------------------------------|<--  old_sp == vfp
  41    ^  ^  ^  ^   |                               |
  42    |  |  |  |   |                               |
  43    |  |localoff |  Copies of 1st .. 6th         |
  44    |  |  |  |   |  argument if necessary.       |
  45    |  |  |  v   |                               |
  46    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  47    |  |  |      |                               |
  48    |  |  |      |  Locals and temporaries.      |
  49    |  |  |      |                               |
  50    |  |  |      |-------------------------------|
  51    |  |  |      |                               |
  52    |-fregoffset |  Saved float registers.       |
  53    |  |  |      |  F9                           |
  54    |  |  |      |   .                           |
  55    |  |  |      |   .                           |
  56    |  |  |      |  F2                           |
  57    |  |  v      |                               |
  58    |  |  -------|-------------------------------|
  59    |  |         |                               |
  60    |  |         |  Saved registers.             |
  61    |  |         |  S6                           |
  62    |-regoffset  |   .                           |
  63    |  |         |   .                           |
  64    |  |         |  S0                           |
  65    |  |         |  pdr.pcreg                    |
  66    |  v         |                               |
  67    |  ----------|-------------------------------|
  68    |            |                               |
  69  frameoffset    |  Argument build area, gets    |
  70    |            |  7th ... nth arg for any      |
  71    |            |  called procedure.            |
  72    v            |                               |
  73    -------------|-------------------------------|<-- sp
  74                 |                               |
  75 */
  76
  77 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  78 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  79 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  80 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  81 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  82 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  83 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  84 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  85 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  86 \f
  87 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  88    be found; you'll have to fall back to other methods in that case.  */
  89
  90 static struct mdebug_extra_func_info *
  91 find_proc_desc (CORE_ADDR pc)
  92 {
  93   const struct block *b = block_for_pc (pc);
  94   struct mdebug_extra_func_info *proc_desc = NULL;
  95   struct symbol *sym = NULL;
  96   const char *sh_name = NULL;
  97
  98   if (b)
  99     {
 100       CORE_ADDR startaddr;
 101       find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
 102
 103       if (startaddr > b->start ())
 104         /* This is the "pathological" case referred to in a comment in
 105            print_frame_info.  It might be better to move this check into
 106            symbol reading.  */
 107         sym = NULL;
 108       else
 109         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN,
 110                              0).symbol;
 111     }
 112
 113   if (sym)
 114     {
 115       proc_desc = (struct mdebug_extra_func_info *) sym->value_bytes ();
 116
 117       /* Correct incorrect setjmp procedure descriptor from the library
 118          to make backtrace through setjmp work.  */
 119       if (proc_desc->pdr.pcreg == 0
 120           && strcmp (sh_name, "setjmp") == 0)
 121         {
 122           proc_desc->pdr.pcreg = ALPHA_RA_REGNUM;
 123           proc_desc->pdr.regmask = 0x80000000;
 124           proc_desc->pdr.regoffset = -4;
 125         }
 126
 127       /* If we never found a PDR for this function in symbol reading,
 128          then examine prologues to find the information.  */
 129       if (proc_desc->pdr.framereg == -1)
 130         proc_desc = NULL;
 131     }
 132
 133   return proc_desc;
 134 }
 135
 136 /* Return a non-zero result if the function is frameless; zero otherwise.  */
 137
 138 static int
 139 alpha_mdebug_frameless (struct mdebug_extra_func_info *proc_desc)
 140 {
 141   return (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 142           && PROC_FRAME_OFFSET (proc_desc) == 0);
 143 }
 144
 145 /* This returns the PC of the first inst after the prologue.  If we can't
 146    find the prologue, then return 0.  */
 147
 148 static CORE_ADDR
 149 alpha_mdebug_after_prologue (CORE_ADDR pc,
 150                              struct mdebug_extra_func_info *proc_desc)
 151 {
 152   if (proc_desc)
 153     {
 154       /* If function is frameless, then we need to do it the hard way.  I
 155          strongly suspect that frameless always means prologueless...  */
 156       if (alpha_mdebug_frameless (proc_desc))
 157         return 0;
 158     }
 159
 160   return alpha_after_prologue (pc);
 161 }
 162
 163 /* Return non-zero if we *might* be in a function prologue.  Return zero
 164    if we are definitively *not* in a function prologue.  */
 165
 166 static int
 167 alpha_mdebug_in_prologue (CORE_ADDR pc,
 168                           struct mdebug_extra_func_info *proc_desc)
 169 {
 170   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 171   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 172 }
 173
 174 \f
 175 /* Frame unwinder that reads mdebug PDRs.  */
 176
 177 struct alpha_mdebug_unwind_cache
 178 {
 179   struct mdebug_extra_func_info *proc_desc;
 180   CORE_ADDR vfp;
 181   trad_frame_saved_reg *saved_regs;
 182 };
 183
 184 /* Extract all of the information about the frame from PROC_DESC
 185    and store the resulting register save locations in the structure.  */
 186
 187 static struct alpha_mdebug_unwind_cache *
 188 alpha_mdebug_frame_unwind_cache (frame_info_ptr this_frame,
 189                                  void **this_prologue_cache)
 190 {
 191   struct alpha_mdebug_unwind_cache *info;
 192   struct mdebug_extra_func_info *proc_desc;
 193   ULONGEST vfp;
 194   CORE_ADDR pc, reg_position;
 195   unsigned long mask;
 196   int ireg, returnreg;
 197
 198   if (*this_prologue_cache)
 199     return (struct alpha_mdebug_unwind_cache *) *this_prologue_cache;
 200
 201   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 202   *this_prologue_cache = info;
 203   pc = get_frame_address_in_block (this_frame);
 204
 205   /* ??? We don't seem to be able to cache the lookup of the PDR
 206      from alpha_mdebug_frame_p.  It'd be nice if we could change
 207      the arguments to that function.  Oh well.  */
 208   proc_desc = find_proc_desc (pc);
 209   info->proc_desc = proc_desc;
 210   gdb_assert (proc_desc != NULL);
 211
 212   info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 213
 214   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 215   vfp = get_frame_register_unsigned (this_frame, PROC_FRAME_REG (proc_desc));
 216   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 217   info->vfp = vfp;
 218
 219   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 220
 221   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 222   mask = PROC_REG_MASK (proc_desc);
 223   returnreg = PROC_PC_REG (proc_desc);
 224
 225   /* Note that RA is always saved first, regardless of its actual
 226      register number.  */
 227   if (mask & (1 << returnreg))
 228     {
 229       /* Clear bit for RA so we don't save it again later.  */
 230       mask &= ~(1 << returnreg);
 231
 232       info->saved_regs[returnreg].set_addr (reg_position);
 233       reg_position += 8;
 234     }
 235
 236   for (ireg = 0; ireg <= 31; ++ireg)
 237     if (mask & (1 << ireg))
 238       {
 239         info->saved_regs[ireg].set_addr (reg_position);
 240         reg_position += 8;
 241       }
 242
 243   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 244   mask = PROC_FREG_MASK (proc_desc);
 245
 246   for (ireg = 0; ireg <= 31; ++ireg)
 247     if (mask & (1 << ireg))
 248       {
 249         info->saved_regs[ALPHA_FP0_REGNUM + ireg].set_addr (reg_position);
 250         reg_position += 8;
 251       }
 252
 253   /* The stack pointer of the previous frame is computed by popping
 254      the current stack frame.  */
 255   if (!info->saved_regs[ALPHA_SP_REGNUM].is_addr ())
 256     info->saved_regs[ALPHA_SP_REGNUM].set_value (vfp);
 257
 258   return info;
 259 }
 260
 261 /* Given a GDB frame, determine the address of the calling function's
 262    frame.  This will be used to create a new GDB frame struct.  */
 263
 264 static void
 265 alpha_mdebug_frame_this_id (frame_info_ptr this_frame,
 266                             void **this_prologue_cache,
 267                             struct frame_id *this_id)
 268 {
 269   struct alpha_mdebug_unwind_cache *info
 270     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 271
 272   *this_id = frame_id_build (info->vfp, get_frame_func (this_frame));
 273 }
 274
 275 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 276
 277 static struct value *
 278 alpha_mdebug_frame_prev_register (frame_info_ptr this_frame,
 279                                   void **this_prologue_cache, int regnum)
 280 {
 281   struct alpha_mdebug_unwind_cache *info
 282     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 283
 284   /* The PC of the previous frame is stored in the link register of
 285      the current frame.  Frob regnum so that we pull the value from
 286      the correct place.  */
 287   if (regnum == ALPHA_PC_REGNUM)
 288     regnum = PROC_PC_REG (info->proc_desc);
 289
 290   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 291 }
 292
 293 /* Return a non-zero result if the size of the stack frame exceeds the
 294    maximum debuggable frame size (512 Kbytes); zero otherwise.  */
 295
 296 static int
 297 alpha_mdebug_max_frame_size_exceeded (struct mdebug_extra_func_info *proc_desc)
 298 {
 299   /* If frame offset is null, we can be in two cases: either the
 300      function is frameless (the stack frame is null) or its
 301      frame exceeds the maximum debuggable frame size (512 Kbytes).  */
 302
 303   return (PROC_FRAME_OFFSET (proc_desc) == 0
 304           && !alpha_mdebug_frameless (proc_desc));
 305 }
 306
 307 static int
 308 alpha_mdebug_frame_sniffer (const struct frame_unwind *self,
 309                             frame_info_ptr this_frame,
 310                             void **this_cache)
 311 {
 312   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 313   struct mdebug_extra_func_info *proc_desc;
 314
 315   /* If this PC does not map to a PDR, then clearly this isn't an
 316      mdebug frame.  */
 317   proc_desc = find_proc_desc (pc);
 318   if (proc_desc == NULL)
 319     return 0;
 320
 321   /* If we're in the prologue, the PDR for this frame is not yet valid.
 322      Say no here and we'll fall back on the heuristic unwinder.  */
 323   if (alpha_mdebug_in_prologue (pc, proc_desc))
 324     return 0;
 325
 326   /* If the maximum debuggable frame size has been exceeded, the
 327      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 328   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 329     return 0;
 330
 331   return 1;
 332 }
 333
 334 static const struct frame_unwind alpha_mdebug_frame_unwind =
 335 {
 336   "alpha mdebug",
 337   NORMAL_FRAME,
 338   default_frame_unwind_stop_reason,
 339   alpha_mdebug_frame_this_id,
 340   alpha_mdebug_frame_prev_register,
 341   NULL,
 342   alpha_mdebug_frame_sniffer
 343 };
 344
 345 static CORE_ADDR
 346 alpha_mdebug_frame_base_address (frame_info_ptr this_frame,
 347                                  void **this_prologue_cache)
 348 {
 349   struct alpha_mdebug_unwind_cache *info
 350     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 351
 352   return info->vfp;
 353 }
 354
 355 static CORE_ADDR
 356 alpha_mdebug_frame_locals_address (frame_info_ptr this_frame,
 357                                    void **this_prologue_cache)
 358 {
 359   struct alpha_mdebug_unwind_cache *info
 360     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 361
 362   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 363 }
 364
 365 static CORE_ADDR
 366 alpha_mdebug_frame_args_address (frame_info_ptr this_frame,
 367                                  void **this_prologue_cache)
 368 {
 369   struct alpha_mdebug_unwind_cache *info
 370     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 371
 372   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 373 }
 374
 375 static const struct frame_base alpha_mdebug_frame_base = {
 376   &alpha_mdebug_frame_unwind,
 377   alpha_mdebug_frame_base_address,
 378   alpha_mdebug_frame_locals_address,
 379   alpha_mdebug_frame_args_address
 380 };
 381
 382 static const struct frame_base *
 383 alpha_mdebug_frame_base_sniffer (frame_info_ptr this_frame)
 384 {
 385   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 386   struct mdebug_extra_func_info *proc_desc;
 387
 388   /* If this PC does not map to a PDR, then clearly this isn't an
 389      mdebug frame.  */
 390   proc_desc = find_proc_desc (pc);
 391   if (proc_desc == NULL)
 392     return NULL;
 393
 394   /* If the maximum debuggable frame size has been exceeded, the
 395      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 396   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 397     return 0;
 398
 399   return &alpha_mdebug_frame_base;
 400 }
 401
 402 \f
 403 void
 404 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 405 {
 406   frame_unwind_append_unwinder (gdbarch, &alpha_mdebug_frame_unwind);
 407   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 408 }