gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for MIPS systems running NetBSD.
   2    Copyright 2002, 2003, 2004 Free Software Foundation, Inc.
   3    Contributed by Wasabi Systems, 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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25 #include "target.h"
  26 #include "value.h"
  27 #include "osabi.h"
  28
  29 #include "nbsd-tdep.h"
  30 #include "mipsnbsd-tdep.h"
  31 #include "mips-tdep.h"
  32
  33 #include "solib-svr4.h"
  34
  35 /* Conveniently, GDB uses the same register numbering as the
  36    ptrace register structure used by NetBSD/mips.  */
  37
  38 void
  39 mipsnbsd_supply_reg (char *regs, int regno)
  40 {
  41   int i;
  42
  43   for (i = 0; i <= PC_REGNUM; i++)
  44     {
  45       if (regno == i || regno == -1)
  46         {
  47           if (CANNOT_FETCH_REGISTER (i))
  48             supply_register (i, NULL);
  49           else
  50             supply_register (i, regs + (i * mips_regsize (current_gdbarch)));
  51         }
  52     }
  53 }
  54
  55 void
  56 mipsnbsd_fill_reg (char *regs, int regno)
  57 {
  58   int i;
  59
  60   for (i = 0; i <= PC_REGNUM; i++)
  61     if ((regno == i || regno == -1) && ! CANNOT_STORE_REGISTER (i))
  62       regcache_collect (i, regs + (i * mips_regsize (current_gdbarch)));
  63 }
  64
  65 void
  66 mipsnbsd_supply_fpreg (char *fpregs, int regno)
  67 {
  68   int i;
  69
  70   for (i = FP0_REGNUM;
  71        i <= mips_regnum (current_gdbarch)->fp_implementation_revision;
  72        i++)
  73     {
  74       if (regno == i || regno == -1)
  75         {
  76           if (CANNOT_FETCH_REGISTER (i))
  77             supply_register (i, NULL);
  78           else
  79             supply_register (i, fpregs + ((i - FP0_REGNUM) * mips_regsize (current_gdbarch)));
  80         }
  81     }
  82 }
  83
  84 void
  85 mipsnbsd_fill_fpreg (char *fpregs, int regno)
  86 {
  87   int i;
  88
  89   for (i = FP0_REGNUM; i <= mips_regnum (current_gdbarch)->fp_control_status;
  90        i++)
  91     if ((regno == i || regno == -1) && ! CANNOT_STORE_REGISTER (i))
  92       regcache_collect (i, fpregs + ((i - FP0_REGNUM) * mips_regsize (current_gdbarch)));
  93 }
  94
  95 static void
  96 fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which,
  97                       CORE_ADDR ignore)
  98 {
  99   char *regs, *fpregs;
 100
 101   /* We get everything from one section.  */
 102   if (which != 0)
 103     return;
 104
 105   regs = core_reg_sect;
 106   fpregs = core_reg_sect + SIZEOF_STRUCT_REG;
 107
 108   /* Integer registers.  */
 109   mipsnbsd_supply_reg (regs, -1);
 110
 111   /* Floating point registers.  */
 112   mipsnbsd_supply_fpreg (fpregs, -1);
 113 }
 114
 115 static void
 116 fetch_elfcore_registers (char *core_reg_sect, unsigned core_reg_size, int which,
 117                          CORE_ADDR ignore)
 118 {
 119   switch (which)
 120     {
 121     case 0:  /* Integer registers.  */
 122       if (core_reg_size != SIZEOF_STRUCT_REG)
 123         warning ("Wrong size register set in core file.");
 124       else
 125         mipsnbsd_supply_reg (core_reg_sect, -1);
 126       break;
 127
 128     case 2:  /* Floating point registers.  */
 129       if (core_reg_size != SIZEOF_STRUCT_FPREG)
 130         warning ("Wrong size register set in core file.");
 131       else
 132         mipsnbsd_supply_fpreg (core_reg_sect, -1);
 133       break;
 134
 135     default:
 136       /* Don't know what kind of register request this is; just ignore it.  */
 137       break;
 138     }
 139 }
 140
 141 static struct core_fns mipsnbsd_core_fns =
 142 {
 143   bfd_target_unknown_flavour,           /* core_flavour */
 144   default_check_format,                 /* check_format */
 145   default_core_sniffer,                 /* core_sniffer */
 146   fetch_core_registers,                 /* core_read_registers */
 147   NULL                                  /* next */
 148 };
 149
 150 static struct core_fns mipsnbsd_elfcore_fns =
 151 {
 152   bfd_target_elf_flavour,               /* core_flavour */
 153   default_check_format,                 /* check_format */
 154   default_core_sniffer,                 /* core_sniffer */
 155   fetch_elfcore_registers,              /* core_read_registers */
 156   NULL                                  /* next */
 157 };
 158
 159 /* Under NetBSD/mips, signal handler invocations can be identified by the
 160    designated code sequence that is used to return from a signal handler.
 161    In particular, the return address of a signal handler points to the
 162    following code sequence:
 163
 164         addu    a0, sp, 16
 165         li      v0, 295                 # __sigreturn14
 166         syscall
 167
 168    Each instruction has a unique encoding, so we simply attempt to match
 169    the instruction the PC is pointing to with any of the above instructions.
 170    If there is a hit, we know the offset to the start of the designated
 171    sequence and can then check whether we really are executing in the
 172    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 173    start of the return sequence is returned.  */
 174
 175 #define RETCODE_NWORDS  3
 176 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 177
 178 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 179 {
 180   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 181   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 182   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 183 };
 184
 185 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 186 {
 187   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 188   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 189   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 190 };
 191
 192 static LONGEST
 193 mipsnbsd_sigtramp_offset (CORE_ADDR pc)
 194 {
 195   const char *retcode = TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
 196         ? sigtramp_retcode_mipseb : sigtramp_retcode_mipsel;
 197   unsigned char ret[RETCODE_SIZE], w[4];
 198   LONGEST off;
 199   int i;
 200
 201   if (read_memory_nobpt (pc, (char *) w, sizeof (w)) != 0)
 202     return -1;
 203
 204   for (i = 0; i < RETCODE_NWORDS; i++)
 205     {
 206       if (memcmp (w, retcode + (i * 4), 4) == 0)
 207         break;
 208     }
 209   if (i == RETCODE_NWORDS)
 210     return -1;
 211
 212   off = i * 4;
 213   pc -= off;
 214
 215   if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
 216     return -1;
 217
 218   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 219     return off;
 220
 221   return -1;
 222 }
 223
 224 static int
 225 mipsnbsd_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
 226 {
 227   return (nbsd_pc_in_sigtramp (pc, func_name)
 228           || mipsnbsd_sigtramp_offset (pc) >= 0);
 229 }
 230
 231 /* Figure out where the longjmp will land.  We expect that we have
 232    just entered longjmp and haven't yet setup the stack frame, so
 233    the args are still in the argument regs.  A0_REGNUM points at the
 234    jmp_buf structure from which we extract the PC that we will land
 235    at.  The PC is copied into *pc.  This routine returns true on
 236    success.  */
 237
 238 #define NBSD_MIPS_JB_PC                 (2 * 4)
 239 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_regsize (current_gdbarch)
 240 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 241                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 242
 243 static int
 244 mipsnbsd_get_longjmp_target (CORE_ADDR *pc)
 245 {
 246   CORE_ADDR jb_addr;
 247   char *buf;
 248
 249   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 250
 251   jb_addr = read_register (A0_REGNUM);
 252
 253   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 254                           NBSD_MIPS_JB_ELEMENT_SIZE))
 255     return 0;
 256
 257   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 258
 259   return 1;
 260 }
 261
 262 static int
 263 mipsnbsd_cannot_fetch_register (int regno)
 264 {
 265   return (regno == ZERO_REGNUM
 266           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 267 }
 268
 269 static int
 270 mipsnbsd_cannot_store_register (int regno)
 271 {
 272   return (regno == ZERO_REGNUM
 273           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 274 }
 275
 276 /* NetBSD/mips uses a slightly different link_map structure from the
 277    other NetBSD platforms.  */
 278 static struct link_map_offsets *
 279 mipsnbsd_ilp32_solib_svr4_fetch_link_map_offsets (void)
 280 {
 281   static struct link_map_offsets lmo;
 282   static struct link_map_offsets *lmp = NULL;
 283
 284   if (lmp == NULL)
 285     {
 286       lmp = &lmo;
 287
 288       lmo.r_debug_size = 16;
 289
 290       lmo.r_map_offset = 4;
 291       lmo.r_map_size   = 4;
 292
 293       lmo.link_map_size = 24;
 294
 295       lmo.l_addr_offset = 0;
 296       lmo.l_addr_size   = 4;
 297
 298       lmo.l_name_offset = 8;
 299       lmo.l_name_size   = 4;
 300
 301       lmo.l_next_offset = 16;
 302       lmo.l_next_size   = 4;
 303
 304       lmo.l_prev_offset = 20;
 305       lmo.l_prev_size   = 4;
 306     }
 307
 308   return lmp;
 309 }
 310
 311 static struct link_map_offsets *
 312 mipsnbsd_lp64_solib_svr4_fetch_link_map_offsets (void)
 313 {
 314   static struct link_map_offsets lmo;
 315   static struct link_map_offsets *lmp = NULL;
 316
 317   if (lmp == NULL)
 318     {
 319       lmp = &lmo;
 320
 321       lmo.r_debug_size = 32;
 322
 323       lmo.r_map_offset = 8;
 324       lmo.r_map_size   = 8;
 325
 326       lmo.link_map_size = 48;
 327
 328       lmo.l_addr_offset = 0;
 329       lmo.l_addr_size   = 8;
 330
 331       lmo.l_name_offset = 16;
 332       lmo.l_name_size   = 8;
 333
 334       lmo.l_next_offset = 32;
 335       lmo.l_next_size   = 8;
 336
 337       lmo.l_prev_offset = 40;
 338       lmo.l_prev_size   = 8;
 339     }
 340
 341   return lmp;
 342 }
 343
 344 static void
 345 mipsnbsd_init_abi (struct gdbarch_info info,
 346                    struct gdbarch *gdbarch)
 347 {
 348   set_gdbarch_deprecated_pc_in_sigtramp (gdbarch, mipsnbsd_pc_in_sigtramp);
 349
 350   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 351
 352   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 353   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 354
 355   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 356
 357   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 358                                          gdbarch_ptr_bit (gdbarch) == 32 ?
 359                             mipsnbsd_ilp32_solib_svr4_fetch_link_map_offsets :
 360                             mipsnbsd_lp64_solib_svr4_fetch_link_map_offsets);
 361 }
 362
 363 void
 364 _initialize_mipsnbsd_tdep (void)
 365 {
 366   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 367                           mipsnbsd_init_abi);
 368
 369   deprecated_add_core_fns (&mipsnbsd_core_fns);
 370   deprecated_add_core_fns (&mipsnbsd_elfcore_fns);
 371 }