gdb/alpha-mdebug-tdep.c

   1 /* Target-dependent mdebug code for the ALPHA architecture.
   2    Copyright (C) 1993-2018 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
  31 /* FIXME: Some of this code should perhaps be merged with mips.  */
  32
  33 /* *INDENT-OFF* */
  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 /* *INDENT-ON* */
  77
  78 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  79 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  80 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  81 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  82 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  83 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  84 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  85 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  86 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  87 \f
  88 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  89    be found; you'll have to fall back to other methods in that case.  */
  90
  91 static struct mdebug_extra_func_info *
  92 find_proc_desc (CORE_ADDR pc)
  93 {
  94   const struct block *b = block_for_pc (pc);
  95   struct mdebug_extra_func_info *proc_desc = NULL;
  96   struct symbol *sym = NULL;
  97   const char *sh_name = NULL;
  98
  99   if (b)
 100     {
 101       CORE_ADDR startaddr;
 102       find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
 103
 104       if (startaddr > BLOCK_START (b))
 105         /* This is the "pathological" case referred to in a comment in
 106            print_frame_info.  It might be better to move this check into
 107            symbol reading.  */
 108         sym = NULL;
 109       else
 110         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN,
 111                              0).symbol;
 112     }
 113
 114   if (sym)
 115     {
 116       proc_desc = (struct mdebug_extra_func_info *) SYMBOL_VALUE_BYTES (sym);
 117
 118       /* Correct incorrect setjmp procedure descriptor from the library
 119          to make backtrace through setjmp work.  */
 120       if (proc_desc->pdr.pcreg == 0
 121           && strcmp (sh_name, "setjmp") == 0)
 122         {
 123           proc_desc->pdr.pcreg = ALPHA_RA_REGNUM;
 124           proc_desc->pdr.regmask = 0x80000000;
 125           proc_desc->pdr.regoffset = -4;
 126         }
 127
 128       /* If we never found a PDR for this function in symbol reading,
 129          then examine prologues to find the information.  */
 130       if (proc_desc->pdr.framereg == -1)
 131         proc_desc = NULL;
 132     }
 133
 134   return proc_desc;
 135 }
 136
 137 /* Return a non-zero result if the function is frameless; zero otherwise.  */
 138
 139 static int
 140 alpha_mdebug_frameless (struct mdebug_extra_func_info *proc_desc)
 141 {
 142   return (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 143           && PROC_FRAME_OFFSET (proc_desc) == 0);
 144 }
 145
 146 /* This returns the PC of the first inst after the prologue.  If we can't
 147    find the prologue, then return 0.  */
 148
 149 static CORE_ADDR
 150 alpha_mdebug_after_prologue (CORE_ADDR pc,
 151                              struct mdebug_extra_func_info *proc_desc)
 152 {
 153   if (proc_desc)
 154     {
 155       /* If function is frameless, then we need to do it the hard way.  I
 156          strongly suspect that frameless always means prologueless...  */
 157       if (alpha_mdebug_frameless (proc_desc))
 158         return 0;
 159     }
 160
 161   return alpha_after_prologue (pc);
 162 }
 163
 164 /* Return non-zero if we *might* be in a function prologue.  Return zero
 165    if we are definitively *not* in a function prologue.  */
 166
 167 static int
 168 alpha_mdebug_in_prologue (CORE_ADDR pc,
 169                           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 (struct alpha_mdebug_unwind_cache *) *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   default_frame_unwind_stop_reason,
 338   alpha_mdebug_frame_this_id,
 339   alpha_mdebug_frame_prev_register,
 340   NULL,
 341   alpha_mdebug_frame_sniffer
 342 };
 343
 344 static CORE_ADDR
 345 alpha_mdebug_frame_base_address (struct frame_info *this_frame,
 346                                  void **this_prologue_cache)
 347 {
 348   struct alpha_mdebug_unwind_cache *info
 349     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 350
 351   return info->vfp;
 352 }
 353
 354 static CORE_ADDR
 355 alpha_mdebug_frame_locals_address (struct frame_info *this_frame,
 356                                    void **this_prologue_cache)
 357 {
 358   struct alpha_mdebug_unwind_cache *info
 359     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 360
 361   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 362 }
 363
 364 static CORE_ADDR
 365 alpha_mdebug_frame_args_address (struct frame_info *this_frame,
 366                                  void **this_prologue_cache)
 367 {
 368   struct alpha_mdebug_unwind_cache *info
 369     = alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
 370
 371   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 372 }
 373
 374 static const struct frame_base alpha_mdebug_frame_base = {
 375   &alpha_mdebug_frame_unwind,
 376   alpha_mdebug_frame_base_address,
 377   alpha_mdebug_frame_locals_address,
 378   alpha_mdebug_frame_args_address
 379 };
 380
 381 static const struct frame_base *
 382 alpha_mdebug_frame_base_sniffer (struct frame_info *this_frame)
 383 {
 384   CORE_ADDR pc = get_frame_address_in_block (this_frame);
 385   struct mdebug_extra_func_info *proc_desc;
 386
 387   /* If this PC does not map to a PDR, then clearly this isn't an
 388      mdebug frame.  */
 389   proc_desc = find_proc_desc (pc);
 390   if (proc_desc == NULL)
 391     return NULL;
 392
 393   /* If the maximum debuggable frame size has been exceeded, the
 394      proc desc is bogus.  Fall back on the heuristic unwinder.  */
 395   if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
 396     return 0;
 397
 398   return &alpha_mdebug_frame_base;
 399 }
 400
 401 \f
 402 void
 403 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 404 {
 405   frame_unwind_append_unwinder (gdbarch, &alpha_mdebug_frame_unwind);
 406   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 407 }