gdb/trad-frame.c

   1 /* Traditional frame unwind support, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2003-2019 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 "trad-frame.h"
  23 #include "regcache.h"
  24 #include "frame-unwind.h"
  25 #include "target.h"
  26 #include "value.h"
  27
  28 struct trad_frame_cache
  29 {
  30   struct frame_info *this_frame;
  31   CORE_ADDR this_base;
  32   struct trad_frame_saved_reg *prev_regs;
  33   struct frame_id this_id;
  34 };
  35
  36 struct trad_frame_cache *
  37 trad_frame_cache_zalloc (struct frame_info *this_frame)
  38 {
  39   struct trad_frame_cache *this_trad_cache;
  40
  41   this_trad_cache = FRAME_OBSTACK_ZALLOC (struct trad_frame_cache);
  42   this_trad_cache->prev_regs = trad_frame_alloc_saved_regs (this_frame);
  43   this_trad_cache->this_frame = this_frame;
  44   return this_trad_cache;
  45 }
  46
  47 /* See trad-frame.h.  */
  48
  49 void
  50 trad_frame_reset_saved_regs (struct gdbarch *gdbarch,
  51                              struct trad_frame_saved_reg *regs)
  52 {
  53   int numregs = gdbarch_num_cooked_regs (gdbarch);
  54   for (int regnum = 0; regnum < numregs; regnum++)
  55     {
  56       regs[regnum].realreg = regnum;
  57       regs[regnum].addr = -1;
  58     }
  59 }
  60
  61 struct trad_frame_saved_reg *
  62 trad_frame_alloc_saved_regs (struct gdbarch *gdbarch)
  63 {
  64   int numregs = gdbarch_num_cooked_regs (gdbarch);
  65   struct trad_frame_saved_reg *this_saved_regs
  66     = FRAME_OBSTACK_CALLOC (numregs, struct trad_frame_saved_reg);
  67
  68   trad_frame_reset_saved_regs (gdbarch, this_saved_regs);
  69   return this_saved_regs;
  70 }
  71
  72 /* A traditional frame is unwound by analysing the function prologue
  73    and using the information gathered to track registers.  For
  74    non-optimized frames, the technique is reliable (just need to check
  75    for all potential instruction sequences).  */
  76
  77 struct trad_frame_saved_reg *
  78 trad_frame_alloc_saved_regs (struct frame_info *this_frame)
  79 {
  80   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  81
  82   return trad_frame_alloc_saved_regs (gdbarch);
  83 }
  84
  85 enum { TF_REG_VALUE = -1, TF_REG_UNKNOWN = -2 };
  86
  87 int
  88 trad_frame_value_p (struct trad_frame_saved_reg this_saved_regs[], int regnum)
  89 {
  90   return (this_saved_regs[regnum].realreg == TF_REG_VALUE);
  91 }
  92
  93 int
  94 trad_frame_addr_p (struct trad_frame_saved_reg this_saved_regs[], int regnum)
  95 {
  96   return (this_saved_regs[regnum].realreg >= 0
  97           && this_saved_regs[regnum].addr != -1);
  98 }
  99
 100 int
 101 trad_frame_realreg_p (struct trad_frame_saved_reg this_saved_regs[],
 102                       int regnum)
 103 {
 104   return (this_saved_regs[regnum].realreg >= 0
 105           && this_saved_regs[regnum].addr == -1);
 106 }
 107
 108 void
 109 trad_frame_set_value (struct trad_frame_saved_reg this_saved_regs[],
 110                       int regnum, LONGEST val)
 111 {
 112   /* Make the REALREG invalid, indicating that the ADDR contains the
 113      register's value.  */
 114   this_saved_regs[regnum].realreg = TF_REG_VALUE;
 115   this_saved_regs[regnum].addr = val;
 116 }
 117
 118 /* See trad-frame.h.  */
 119
 120 void
 121 trad_frame_set_realreg (struct trad_frame_saved_reg this_saved_regs[],
 122                         int regnum, int realreg)
 123 {
 124   this_saved_regs[regnum].realreg = realreg;
 125   this_saved_regs[regnum].addr = -1;
 126 }
 127
 128 /* See trad-frame.h.  */
 129
 130 void
 131 trad_frame_set_addr (struct trad_frame_saved_reg this_saved_regs[],
 132                      int regnum, CORE_ADDR addr)
 133 {
 134   this_saved_regs[regnum].realreg = regnum;
 135   this_saved_regs[regnum].addr = addr;
 136 }
 137
 138 void
 139 trad_frame_set_reg_value (struct trad_frame_cache *this_trad_cache,
 140                           int regnum, LONGEST val)
 141 {
 142   /* External interface for users of trad_frame_cache
 143      (who cannot access the prev_regs object directly).  */
 144   trad_frame_set_value (this_trad_cache->prev_regs, regnum, val);
 145 }
 146
 147 void
 148 trad_frame_set_reg_realreg (struct trad_frame_cache *this_trad_cache,
 149                             int regnum, int realreg)
 150 {
 151   trad_frame_set_realreg (this_trad_cache->prev_regs, regnum, realreg);
 152 }
 153
 154 void
 155 trad_frame_set_reg_addr (struct trad_frame_cache *this_trad_cache,
 156                          int regnum, CORE_ADDR addr)
 157 {
 158   trad_frame_set_addr (this_trad_cache->prev_regs, regnum, addr);
 159 }
 160
 161 void
 162 trad_frame_set_reg_regmap (struct trad_frame_cache *this_trad_cache,
 163                            const struct regcache_map_entry *regmap,
 164                            CORE_ADDR addr, size_t size)
 165 {
 166   struct gdbarch *gdbarch = get_frame_arch (this_trad_cache->this_frame);
 167   int offs = 0, count;
 168
 169   for (; (count = regmap->count) != 0; regmap++)
 170     {
 171       int regno = regmap->regno;
 172       int slot_size = regmap->size;
 173
 174       if (slot_size == 0 && regno != REGCACHE_MAP_SKIP)
 175         slot_size = register_size (gdbarch, regno);
 176
 177       if (offs + slot_size > size)
 178         break;
 179
 180       if (regno == REGCACHE_MAP_SKIP)
 181         offs += count * slot_size;
 182       else
 183         for (; count--; regno++, offs += slot_size)
 184           {
 185             /* Mimic the semantics of regcache::transfer_regset if a
 186                register slot's size does not match the size of a
 187                register.
 188
 189                If a register slot is larger than a register, assume
 190                the register's value is stored in the first N bytes of
 191                the slot and ignore the remaining bytes.
 192
 193                If the register slot is smaller than the register,
 194                assume that the slot contains the low N bytes of the
 195                register's value.  Since trad_frame assumes that
 196                registers stored by address are sized according to the
 197                register, read the low N bytes and zero-extend them to
 198                generate a register value.  */
 199             if (slot_size >= register_size (gdbarch, regno))
 200               trad_frame_set_reg_addr (this_trad_cache, regno, addr + offs);
 201             else
 202               {
 203                 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 204                 gdb_byte buf[slot_size];
 205
 206                 if (target_read_memory (addr + offs, buf, sizeof buf) == 0)
 207                   {
 208                     LONGEST val
 209                       = extract_unsigned_integer (buf, sizeof buf, byte_order);
 210                     trad_frame_set_reg_value (this_trad_cache, regno, val);
 211                   }
 212               }
 213           }
 214     }
 215 }
 216
 217 void
 218 trad_frame_set_unknown (struct trad_frame_saved_reg this_saved_regs[],
 219                         int regnum)
 220 {
 221   /* Make the REALREG invalid, indicating that the value is not known.  */
 222   this_saved_regs[regnum].realreg = TF_REG_UNKNOWN;
 223   this_saved_regs[regnum].addr = -1;
 224 }
 225
 226 struct value *
 227 trad_frame_get_prev_register (struct frame_info *this_frame,
 228                               struct trad_frame_saved_reg this_saved_regs[],
 229                               int regnum)
 230 {
 231   if (trad_frame_addr_p (this_saved_regs, regnum))
 232     /* The register was saved in memory.  */
 233     return frame_unwind_got_memory (this_frame, regnum,
 234                                     this_saved_regs[regnum].addr);
 235   else if (trad_frame_realreg_p (this_saved_regs, regnum))
 236     return frame_unwind_got_register (this_frame, regnum,
 237                                       this_saved_regs[regnum].realreg);
 238   else if (trad_frame_value_p (this_saved_regs, regnum))
 239     /* The register's value is available.  */
 240     return frame_unwind_got_constant (this_frame, regnum,
 241                                       this_saved_regs[regnum].addr);
 242   else
 243     return frame_unwind_got_optimized (this_frame, regnum);
 244 }
 245
 246 struct value *
 247 trad_frame_get_register (struct trad_frame_cache *this_trad_cache,
 248                          struct frame_info *this_frame,
 249                          int regnum)
 250 {
 251   return trad_frame_get_prev_register (this_frame, this_trad_cache->prev_regs,
 252                                        regnum);
 253 }
 254
 255 void
 256 trad_frame_set_id (struct trad_frame_cache *this_trad_cache,
 257                    struct frame_id this_id)
 258 {
 259   this_trad_cache->this_id = this_id;
 260 }
 261
 262 void
 263 trad_frame_get_id (struct trad_frame_cache *this_trad_cache,
 264                    struct frame_id *this_id)
 265 {
 266   (*this_id) = this_trad_cache->this_id;
 267 }
 268
 269 void
 270 trad_frame_set_this_base (struct trad_frame_cache *this_trad_cache,
 271                           CORE_ADDR this_base)
 272 {
 273   this_trad_cache->this_base = this_base;
 274 }
 275
 276 CORE_ADDR
 277 trad_frame_get_this_base (struct trad_frame_cache *this_trad_cache)
 278 {
 279   return this_trad_cache->this_base;
 280 }