gdb/trad-frame.c

   1 /* Traditional frame unwind support, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2003-2021 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 #include "gdbarch.h"
  28 #include "gdbsupport/traits.h"
  29
  30 struct trad_frame_cache
  31 {
  32   struct frame_info *this_frame;
  33   CORE_ADDR this_base;
  34   trad_frame_saved_reg *prev_regs;
  35   struct frame_id this_id;
  36 };
  37
  38 struct trad_frame_cache *
  39 trad_frame_cache_zalloc (struct frame_info *this_frame)
  40 {
  41   struct trad_frame_cache *this_trad_cache;
  42
  43   this_trad_cache = FRAME_OBSTACK_ZALLOC (struct trad_frame_cache);
  44   this_trad_cache->prev_regs = trad_frame_alloc_saved_regs (this_frame);
  45   this_trad_cache->this_frame = this_frame;
  46   return this_trad_cache;
  47 }
  48
  49 /* See trad-frame.h.  */
  50
  51 void
  52 trad_frame_reset_saved_regs (struct gdbarch *gdbarch,
  53                              trad_frame_saved_reg *regs)
  54 {
  55   int numregs = gdbarch_num_cooked_regs (gdbarch);
  56
  57   for (int regnum = 0; regnum < numregs; regnum++)
  58     regs[regnum].set_realreg (regnum);
  59 }
  60
  61 trad_frame_saved_reg *
  62 trad_frame_alloc_saved_regs (struct gdbarch *gdbarch)
  63 {
  64 #ifdef HAVE_IS_TRIVIALLY_CONSTRUCTIBLE
  65   gdb_static_assert (std::is_trivially_constructible<trad_frame_saved_reg>::value);
  66 #endif
  67
  68   int numregs = gdbarch_num_cooked_regs (gdbarch);
  69   trad_frame_saved_reg *this_saved_regs
  70     = FRAME_OBSTACK_CALLOC (numregs, trad_frame_saved_reg);
  71
  72   trad_frame_reset_saved_regs (gdbarch, this_saved_regs);
  73   return this_saved_regs;
  74 }
  75
  76 /* A traditional frame is unwound by analysing the function prologue
  77    and using the information gathered to track registers.  For
  78    non-optimized frames, the technique is reliable (just need to check
  79    for all potential instruction sequences).  */
  80
  81 trad_frame_saved_reg *
  82 trad_frame_alloc_saved_regs (struct frame_info *this_frame)
  83 {
  84   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  85
  86   return trad_frame_alloc_saved_regs (gdbarch);
  87 }
  88
  89 int
  90 trad_frame_value_p (trad_frame_saved_reg this_saved_regs[], int regnum)
  91 {
  92   return this_saved_regs[regnum].is_value ();
  93 }
  94
  95 int
  96 trad_frame_addr_p (trad_frame_saved_reg this_saved_regs[], int regnum)
  97 {
  98   return this_saved_regs[regnum].is_addr ();
  99 }
 100
 101 int
 102 trad_frame_realreg_p (trad_frame_saved_reg this_saved_regs[],
 103                       int regnum)
 104 {
 105   return this_saved_regs[regnum].is_realreg ();
 106 }
 107
 108 /* See trad-frame.h.  */
 109
 110 bool
 111 trad_frame_value_bytes_p (trad_frame_saved_reg this_saved_regs[],
 112                           int regnum)
 113 {
 114   return this_saved_regs[regnum].is_value_bytes ();
 115 }
 116
 117 void
 118 trad_frame_set_value (trad_frame_saved_reg this_saved_regs[],
 119                       int regnum, LONGEST val)
 120 {
 121   this_saved_regs[regnum].set_value (val);
 122 }
 123
 124 /* See trad-frame.h.  */
 125
 126 void
 127 trad_frame_set_realreg (trad_frame_saved_reg this_saved_regs[],
 128                         int regnum, int realreg)
 129 {
 130   this_saved_regs[regnum].set_realreg (realreg);
 131 }
 132
 133 /* See trad-frame.h.  */
 134
 135 void
 136 trad_frame_set_addr (trad_frame_saved_reg this_saved_regs[],
 137                      int regnum, CORE_ADDR addr)
 138 {
 139   this_saved_regs[regnum].set_addr (addr);
 140 }
 141
 142 void
 143 trad_frame_set_reg_value (struct trad_frame_cache *this_trad_cache,
 144                           int regnum, LONGEST val)
 145 {
 146   /* External interface for users of trad_frame_cache
 147      (who cannot access the prev_regs object directly).  */
 148   trad_frame_set_value (this_trad_cache->prev_regs, regnum, val);
 149 }
 150
 151 void
 152 trad_frame_set_reg_realreg (struct trad_frame_cache *this_trad_cache,
 153                             int regnum, int realreg)
 154 {
 155   trad_frame_set_realreg (this_trad_cache->prev_regs, regnum, realreg);
 156 }
 157
 158 void
 159 trad_frame_set_reg_addr (struct trad_frame_cache *this_trad_cache,
 160                          int regnum, CORE_ADDR addr)
 161 {
 162   trad_frame_set_addr (this_trad_cache->prev_regs, regnum, addr);
 163 }
 164
 165 void
 166 trad_frame_set_reg_regmap (struct trad_frame_cache *this_trad_cache,
 167                            const struct regcache_map_entry *regmap,
 168                            CORE_ADDR addr, size_t size)
 169 {
 170   struct gdbarch *gdbarch = get_frame_arch (this_trad_cache->this_frame);
 171   int offs = 0, count;
 172
 173   for (; (count = regmap->count) != 0; regmap++)
 174     {
 175       int regno = regmap->regno;
 176       int slot_size = regmap->size;
 177
 178       if (slot_size == 0 && regno != REGCACHE_MAP_SKIP)
 179         slot_size = register_size (gdbarch, regno);
 180
 181       if (offs + slot_size > size)
 182         break;
 183
 184       if (regno == REGCACHE_MAP_SKIP)
 185         offs += count * slot_size;
 186       else
 187         for (; count--; regno++, offs += slot_size)
 188           {
 189             /* Mimic the semantics of regcache::transfer_regset if a
 190                register slot's size does not match the size of a
 191                register.
 192
 193                If a register slot is larger than a register, assume
 194                the register's value is stored in the first N bytes of
 195                the slot and ignore the remaining bytes.
 196
 197                If the register slot is smaller than the register,
 198                assume that the slot contains the low N bytes of the
 199                register's value.  Since trad_frame assumes that
 200                registers stored by address are sized according to the
 201                register, read the low N bytes and zero-extend them to
 202                generate a register value.  */
 203             if (slot_size >= register_size (gdbarch, regno))
 204               trad_frame_set_reg_addr (this_trad_cache, regno, addr + offs);
 205             else
 206               {
 207                 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 208                 gdb_byte buf[slot_size];
 209
 210                 if (target_read_memory (addr + offs, buf, sizeof buf) == 0)
 211                   {
 212                     LONGEST val
 213                       = extract_unsigned_integer (buf, sizeof buf, byte_order);
 214                     trad_frame_set_reg_value (this_trad_cache, regno, val);
 215                   }
 216               }
 217           }
 218     }
 219 }
 220
 221 void
 222 trad_frame_set_unknown (trad_frame_saved_reg this_saved_regs[],
 223                         int regnum)
 224 {
 225   this_saved_regs[regnum].set_unknown ();
 226 }
 227
 228 /* See trad-frame.h.  */
 229
 230 void
 231 trad_frame_set_value_bytes (trad_frame_saved_reg this_saved_regs[],
 232                             int regnum,
 233                             gdb::array_view<const gdb_byte> bytes)
 234 {
 235   /* Allocate the space and copy the data bytes.  */
 236   gdb_byte *data = FRAME_OBSTACK_CALLOC (bytes.size (), gdb_byte);
 237   memcpy (data, bytes.data (), bytes.size ());
 238   this_saved_regs[regnum].set_value_bytes (data);
 239 }
 240
 241 /* See trad-frame.h.  */
 242
 243 void
 244 trad_frame_set_reg_value_bytes (struct trad_frame_cache *this_trad_cache,
 245                                 int regnum,
 246                                 gdb::array_view<const gdb_byte> bytes)
 247 {
 248   /* External interface for users of trad_frame_cache
 249      (who cannot access the prev_regs object directly).  */
 250   trad_frame_set_value_bytes (this_trad_cache->prev_regs, regnum, bytes);
 251 }
 252
 253
 254
 255 struct value *
 256 trad_frame_get_prev_register (struct frame_info *this_frame,
 257                               trad_frame_saved_reg this_saved_regs[],
 258                               int regnum)
 259 {
 260   if (trad_frame_addr_p (this_saved_regs, regnum))
 261     /* The register was saved in memory.  */
 262     return frame_unwind_got_memory (this_frame, regnum,
 263                                     this_saved_regs[regnum].addr ());
 264   else if (trad_frame_realreg_p (this_saved_regs, regnum))
 265     return frame_unwind_got_register (this_frame, regnum,
 266                                       this_saved_regs[regnum].realreg ());
 267   else if (trad_frame_value_p (this_saved_regs, regnum))
 268     /* The register's value is available.  */
 269     return frame_unwind_got_constant (this_frame, regnum,
 270                                       this_saved_regs[regnum].value ());
 271   else if (trad_frame_value_bytes_p (this_saved_regs, regnum))
 272     /* The register's value is available as a sequence of bytes.  */
 273     return frame_unwind_got_bytes (this_frame, regnum,
 274                                    this_saved_regs[regnum].value_bytes ());
 275   else
 276     return frame_unwind_got_optimized (this_frame, regnum);
 277 }
 278
 279 struct value *
 280 trad_frame_get_register (struct trad_frame_cache *this_trad_cache,
 281                          struct frame_info *this_frame,
 282                          int regnum)
 283 {
 284   return trad_frame_get_prev_register (this_frame, this_trad_cache->prev_regs,
 285                                        regnum);
 286 }
 287
 288 void
 289 trad_frame_set_id (struct trad_frame_cache *this_trad_cache,
 290                    struct frame_id this_id)
 291 {
 292   this_trad_cache->this_id = this_id;
 293 }
 294
 295 void
 296 trad_frame_get_id (struct trad_frame_cache *this_trad_cache,
 297                    struct frame_id *this_id)
 298 {
 299   (*this_id) = this_trad_cache->this_id;
 300 }
 301
 302 void
 303 trad_frame_set_this_base (struct trad_frame_cache *this_trad_cache,
 304                           CORE_ADDR this_base)
 305 {
 306   this_trad_cache->this_base = this_base;
 307 }
 308
 309 CORE_ADDR
 310 trad_frame_get_this_base (struct trad_frame_cache *this_trad_cache)
 311 {
 312   return this_trad_cache->this_base;
 313 }