gdb/alpha-mdebug-tdep.c

   1 /* Target-dependent mdebug code for the ALPHA architecture.
   2    Copyright (C) 1993-2020 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 /* *INDENT-OFF* */
  35 /* Layout of a stack frame on the alpha:
  36
  37                 |                               |
  38  pdr members:   |  7th ... nth arg,             |
  39                 |  `pushed' by caller.          |
  40                 |                               |
  41 ----------------|-------------------------------|<--  old_sp == vfp
  42    ^  ^  ^  ^   |                               |
  43    |  |  |  |   |                               |
  44    |  |localoff |  Copies of 1st .. 6th         |
  45    |  |  |  |   |  argument if necessary.       |
  46    |  |  |  v   |                               |
  47    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  48    |  |  |      |                               |
  49    |  |  |      |  Locals and temporaries.      |
  50    |  |  |      |                               |
  51    |  |  |      |-------------------------------|
  52    |  |  |      |                               |
  53    |-fregoffset |  Saved float registers.       |
  54    |  |  |      |  F9                           |
  55    |  |  |      |   .                           |
  56    |  |  |      |   .                           |
  57    |  |  |      |  F2                           |
  58    |  |  v      |                               |
  59    |  |  -------|-------------------------------|
  60    |  |         |                               |
  61    |  |         |  Saved registers.             |
  62    |  |         |  S6                           |
  63    |-regoffset  |   .                           |
  64    |  |         |   .                           |
  65    |  |         |  S0                           |
  66    |  |         |  pdr.pcreg                    |
  67    |  v         |                               |
  68    |  ----------|-------------------------------|
  69    |            |                               |
  70  frameoffset    |  Argument build area, gets    |
  71    |            |  7th ... nth arg for any      |
  72    |            |  called procedure.            |
  73    v            |                               |
  74    -------------|-------------------------------|<-- sp
  75                 |                               |
  76 */
  77 /* *INDENT-ON* */
  78
  79 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  80 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  81 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  82 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  83 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  84 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  85 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  86 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  87 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  88 \f
  89 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  90    be found; you'll have to fall back to other methods in that case.  */
  91
  92 static struct mdebug_extra_func_info *
  93 find_proc_desc (CORE_ADDR pc)
  94 {
  95   const struct block *b = block_for_pc (pc);
  96   struct mdebug_extra_func_info *proc_desc = NULL;
  97   struct symbol *sym = NULL;
  98   const char *sh_name = NULL;
  99
 100   if (b)
 101     {
 102       CORE_ADDR startaddr;
 103       find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
 104
 105       if (startaddr > BLOCK_START (b))
 106         /* This is the "pathological" case referred to in a comment in
 107            print_frame_info.  It might be better to move this check into
 108            symbol reading.  */
 109         sym = NULL;
 110       else
 111         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN,
 112                              0).symbol;
 113     }
 114
 115   if (sym)
 116     {
 117       proc_desc = (struct mdebug_extra_func_info *) SYMBOL_VALUE_BYTES (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 /* Return a non-zero result if the function is frameless; zero otherwise.  */
 139
 140 static int
 141 alpha_mdebug_frameless (struct mdebug_extra_func_info *proc_desc)
 142 {
 143   return (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 144           && PROC_FRAME_OFFSET (proc_desc) == 0);
 145 }
 146
 147 /* This returns the PC of the first inst after the prologue.  If we can't
 148    find the prologue, then return 0.  */
 149
 150 static CORE_ADDR
 151 alpha_mdebug_after_prologue (CORE_ADDR pc,
 152                              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,
 170                           struct mdebug_extra_func_info *proc_desc)
 171 {
 172   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 173   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 174 }
 175
 176 \f
 177 /* Frame unwinder that reads mdebug PDRs.  */
 178
 179 struct alpha_mdebug_unwind_cache
 180 {
 181   struct mdebug_extra_func_info *proc_desc;
 182   CORE_ADDR vfp;
 183   struct trad_frame_saved_reg *saved_regs;
 184 };
 185
 186 /* Extract all of the information about the frame from PROC_DESC
 187    and store the resulting register save locations in the structure.  */
 188
 189 static struct alpha_mdebug_unwind_cache *
 190 alpha_mdebug_frame_unwind_cache (struct frame_info *this_frame,
 191                                  void **this_prologue_cache)
 192 {
 193   struct alpha_mdebug_unwind_cache *info;
 194   struct mdebug_extra_func_info *proc_desc;
 195   ULONGEST vfp;
 196   CORE_ADDR pc, reg_position;
 197   unsigned long mask;
 198   int ireg, returnreg;
 199
 200   if (*this_prologue_cache)
 201     return (struct alpha_mdebug_unwind_cache *) *this_prologue_cache;
 202
 203   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 204   *this_prologue_cache = info;
 205   pc = get_frame_address_in_block (this_frame);
 206
 207   /* ??? We don't seem to be able to cache the lookup of the PDR
 208      from alpha_mdebug_frame_p.  It'd be nice if we could change
 209      the arguments to that function.  Oh well.  */
 210   proc_desc = find_proc_desc (pc);
 211   info->proc_desc = proc_desc;
 212   gdb_assert (proc_desc != NULL);
 213
 214   info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 215
 216   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 217   vfp = get_frame_register_unsigned (this_frame, PROC_FRAME_REG (proc_desc));
 218   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 219   info->vfp = vfp;
 220
 221   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 222
 223   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 224   mask = PROC_REG_MASK (proc_desc);
 225   returnreg = PROC_PC_REG (proc_desc);
 226
 227   /* Note that RA is always saved first, regardless of its actual
 228      register number.  */
 229   if (mask & (1 << returnreg))
 230     {
 231       /* Clear bit for RA so we don't save it again later.  */
 232       mask &= ~(1 << returnreg);
 233
 234       info->saved_regs[returnreg].addr = reg_position;
 235       reg_position += 8;
 236     }
 237
 238   for (ireg = 0; ireg <= 31; ++ireg)
 239     if (mask & (1 << ireg))
 240       {
 241         info->saved_regs[ireg].addr = reg_position;
 242         reg_position += 8;
 243       }
 244
 245   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 246   mask = PROC_FREG_MASK (proc_desc);
 247
 248   for (ireg = 0; ireg <= 31; ++ireg)
 249     if (mask & (1 << ireg))
 250       {
 251         info->saved_regs[ALPHA_FP0_REGNUM + ireg].addr = reg_position;
 252         reg_position += 8;
 253       }
 254
 255   /* The stack pointer of the previous frame is computed by popping
 256      the current stack frame.  */
 257   if (!trad_frame_addr_p (info->saved_regs, ALPHA_SP_REGNUM))
 258    trad_frame_set_value (info->saved_regs, ALPHA_SP_REGNUM, vfp);
 259
 260   return info;
 261 }
 262
 263 /* Given a GDB frame, determine the address of the calling function's
 264    frame.  This will be used to create a new GDB frame struct.  */
 265
 266 static void
 267 alpha_mdebug_frame_this_id (struct frame_info *this_frame,
 268                             void **this_prologue_cache,
 269                             struct frame_id *this_id)
 270 {
 271   struct alpha_mdebug_unwind_cache *info
 272     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 273
 274   *this_id = frame_id_build (info->vfp, get_frame_func (this_frame));
 275 }
 276
 277 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 278
 279 static struct value *
 280 alpha_mdebug_frame_prev_register (struct frame_info *this_frame,
 281                                   void **this_prologue_cache, int regnum)
 282 {
 283   struct alpha_mdebug_unwind_cache *info
 284     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 285
 286   /* The PC of the previous frame is stored in the link register of
 287      the current frame.  Frob regnum so that we pull the value from
 288      the correct place.  */
 289   if (regnum == ALPHA_PC_REGNUM)
 290     regnum = PROC_PC_REG (info->proc_desc);
 291
 292   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 293 }
 294
 295 /* Return a non-zero result if the size of the stack frame exceeds the
 296    maximum debuggable frame size (512 Kbytes); zero otherwise.  */
 297
 298 static int
 299 alpha_mdebug_max_frame_size_exceeded (struct mdebug_extra_func_info *proc_desc)
 300 {
 301   /* If frame offset is null, we can be in two cases: either the
 302      function is frameless (the stack frame is null) or its
 303      frame exceeds the maximum debuggable frame size (512 Kbytes).  */
 304
 305   return (PROC_FRAME_OFFSET (proc_desc) == 0
 306           && !alpha_mdebug_frameless (proc_desc));
 307 }
 308
 309 static int
 310 alpha_mdebug_frame_sniffer (const struct frame_unwind *self,
 311                             struct frame_info *this_frame,
 312                             void **this_cache)
 313 {
 314   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 315   struct mdebug_extra_func_info *proc_desc;
 316
 317   /* If this PC does not map to a PDR, then clearly this isn't an
 318      mdebug frame.  */
 319   proc_desc = find_proc_desc (pc);
 320   if (proc_desc == NULL)
 321     return 0;
 322
 323   /* If we're in the prologue, the PDR for this frame is not yet valid.
 324      Say no here and we'll fall back on the heuristic unwinder.  */
 325   if (alpha_mdebug_in_prologue (pc, proc_desc))
 326     return 0;
 327
 328   /* If the maximum debuggable frame size has been exceeded, the
 329      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 330   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 331     return 0;
 332
 333   return 1;
 334 }
 335
 336 static const struct frame_unwind alpha_mdebug_frame_unwind = {
 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 (struct frame_info *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 (struct frame_info *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 (struct frame_info *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 (struct frame_info *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 }