gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright 2002, 2003, 2004 Free Software Foundation, Inc.
   4    Contributed by Wasabi Systems, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "gdbcore.h"
  25 #include "regcache.h"
  26 #include "regset.h"
  27 #include "target.h"
  28 #include "value.h"
  29 #include "osabi.h"
  30
  31 #include "gdb_assert.h"
  32 #include "gdb_string.h"
  33
  34 #include "nbsd-tdep.h"
  35 #include "mipsnbsd-tdep.h"
  36 #include "mips-tdep.h"
  37
  38 #include "solib-svr4.h"
  39
  40 /* Shorthand for some register numbers used below.  */
  41 #define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
  42 #define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
  43 #define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
  44
  45 /* Core file support.  */
  46
  47 /* Number of registers in `struct reg' from <machine/reg.h>.  */
  48 #define MIPSNBSD_NUM_GREGS      38
  49
  50 /* Number of registers in `struct fpreg' from <machine/reg.h>.  */
  51 #define MIPSNBSD_NUM_FPREGS     33
  52
  53 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  54    in the floating-point register set REGSET to register cache
  55    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  56
  57 static void
  58 mipsnbsd_supply_fpregset (const struct regset *regset,
  59                           struct regcache *regcache,
  60                           int regnum, const void *fpregs, size_t len)
  61 {
  62   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  63   const char *regs = fpregs;
  64   int i;
  65
  66   gdb_assert (len >= MIPSNBSD_NUM_FPREGS * regsize);
  67
  68   for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
  69     {
  70       if (regnum == i || regnum == -1)
  71         regcache_raw_supply (regcache, i,
  72                              regs + (i - MIPS_FP0_REGNUM) * regsize);
  73     }
  74 }
  75
  76 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  77    in the general-purpose register set REGSET to register cache
  78    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  79
  80 static void
  81 mipsnbsd_supply_gregset (const struct regset *regset,
  82                          struct regcache *regcache, int regnum,
  83                          const void *gregs, size_t len)
  84 {
  85   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  86   const char *regs = gregs;
  87   int i;
  88
  89   gdb_assert (len >= MIPSNBSD_NUM_GREGS * regsize);
  90
  91   for (i = 0; i <= MIPS_PC_REGNUM; i++)
  92     {
  93       if (regnum == i || regnum == -1)
  94         regcache_raw_supply (regcache, i, regs + i * regsize);
  95     }
  96
  97   if (len >= (MIPSNBSD_NUM_GREGS + MIPSNBSD_NUM_FPREGS) * regsize)
  98     {
  99       regs += MIPSNBSD_NUM_GREGS * regsize;
 100       len -= MIPSNBSD_NUM_GREGS * regsize;
 101       mipsnbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 102     }
 103 }
 104
 105 /* NetBSD/mips register sets.  */
 106
 107 static struct regset mipsnbsd_gregset =
 108 {
 109   NULL,
 110   mipsnbsd_supply_gregset
 111 };
 112
 113 static struct regset mipsnbsd_fpregset =
 114 {
 115   NULL,
 116   mipsnbsd_supply_fpregset
 117 };
 118
 119 /* Return the appropriate register set for the core section identified
 120    by SECT_NAME and SECT_SIZE.  */
 121
 122 static const struct regset *
 123 mipsnbsd_regset_from_core_section (struct gdbarch *gdbarch,
 124                                    const char *sect_name, size_t sect_size)
 125 {
 126   size_t regsize = mips_isa_regsize (gdbarch);
 127
 128   if (strcmp (sect_name, ".reg") == 0
 129       && sect_size >= MIPSNBSD_NUM_GREGS * regsize)
 130     return &mipsnbsd_gregset;
 131
 132   if (strcmp (sect_name, ".reg2") == 0
 133       && sect_size >= MIPSNBSD_NUM_FPREGS * regsize)
 134     return &mipsnbsd_fpregset;
 135
 136   return NULL;
 137 }
 138 \f
 139
 140 /* Conveniently, GDB uses the same register numbering as the
 141    ptrace register structure used by NetBSD/mips.  */
 142
 143 void
 144 mipsnbsd_supply_reg (char *regs, int regno)
 145 {
 146   int i;
 147
 148   for (i = 0; i <= PC_REGNUM; i++)
 149     {
 150       if (regno == i || regno == -1)
 151         {
 152           if (CANNOT_FETCH_REGISTER (i))
 153             regcache_raw_supply (current_regcache, i, NULL);
 154           else
 155             regcache_raw_supply (current_regcache, i,
 156                                  regs + (i * mips_isa_regsize (current_gdbarch)));
 157         }
 158     }
 159 }
 160
 161 void
 162 mipsnbsd_fill_reg (char *regs, int regno)
 163 {
 164   int i;
 165
 166   for (i = 0; i <= PC_REGNUM; i++)
 167     if ((regno == i || regno == -1) && ! CANNOT_STORE_REGISTER (i))
 168       regcache_raw_collect (current_regcache, i,
 169                             regs + (i * mips_isa_regsize (current_gdbarch)));
 170 }
 171
 172 void
 173 mipsnbsd_supply_fpreg (char *fpregs, int regno)
 174 {
 175   int i;
 176
 177   for (i = FP0_REGNUM;
 178        i <= mips_regnum (current_gdbarch)->fp_implementation_revision;
 179        i++)
 180     {
 181       if (regno == i || regno == -1)
 182         {
 183           if (CANNOT_FETCH_REGISTER (i))
 184             regcache_raw_supply (current_regcache, i, NULL);
 185           else
 186             regcache_raw_supply (current_regcache, i,
 187                                  fpregs + ((i - FP0_REGNUM) * mips_isa_regsize (current_gdbarch)));
 188         }
 189     }
 190 }
 191
 192 void
 193 mipsnbsd_fill_fpreg (char *fpregs, int regno)
 194 {
 195   int i;
 196
 197   for (i = FP0_REGNUM; i <= mips_regnum (current_gdbarch)->fp_control_status;
 198        i++)
 199     if ((regno == i || regno == -1) && ! CANNOT_STORE_REGISTER (i))
 200       regcache_raw_collect (current_regcache, i,
 201                             fpregs + ((i - FP0_REGNUM) * mips_isa_regsize (current_gdbarch)));
 202 }
 203
 204 /* Under NetBSD/mips, signal handler invocations can be identified by the
 205    designated code sequence that is used to return from a signal handler.
 206    In particular, the return address of a signal handler points to the
 207    following code sequence:
 208
 209         addu    a0, sp, 16
 210         li      v0, 295                 # __sigreturn14
 211         syscall
 212
 213    Each instruction has a unique encoding, so we simply attempt to match
 214    the instruction the PC is pointing to with any of the above instructions.
 215    If there is a hit, we know the offset to the start of the designated
 216    sequence and can then check whether we really are executing in the
 217    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 218    start of the return sequence is returned.  */
 219
 220 #define RETCODE_NWORDS  3
 221 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 222
 223 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 224 {
 225   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 226   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 227   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 228 };
 229
 230 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 231 {
 232   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 233   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 234   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 235 };
 236
 237 static LONGEST
 238 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 239 {
 240   CORE_ADDR pc = frame_pc_unwind (next_frame);
 241   const char *retcode = TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
 242         ? sigtramp_retcode_mipseb : sigtramp_retcode_mipsel;
 243   unsigned char ret[RETCODE_SIZE], w[4];
 244   LONGEST off;
 245   int i;
 246
 247   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 248     return -1;
 249
 250   for (i = 0; i < RETCODE_NWORDS; i++)
 251     {
 252       if (memcmp (w, retcode + (i * 4), 4) == 0)
 253         break;
 254     }
 255   if (i == RETCODE_NWORDS)
 256     return -1;
 257
 258   off = i * 4;
 259   pc -= off;
 260
 261   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 262     return -1;
 263
 264   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 265     return off;
 266
 267   return -1;
 268 }
 269
 270 /* Figure out where the longjmp will land.  We expect that we have
 271    just entered longjmp and haven't yet setup the stack frame, so the
 272    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 273    jmp_buf structure from which we extract the PC that we will land
 274    at.  The PC is copied into *pc.  This routine returns true on
 275    success.  */
 276
 277 #define NBSD_MIPS_JB_PC                 (2 * 4)
 278 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 279 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 280                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 281
 282 static int
 283 mipsnbsd_get_longjmp_target (CORE_ADDR *pc)
 284 {
 285   CORE_ADDR jb_addr;
 286   char *buf;
 287
 288   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 289
 290   jb_addr = read_register (MIPS_A0_REGNUM);
 291
 292   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 293                           NBSD_MIPS_JB_ELEMENT_SIZE))
 294     return 0;
 295
 296   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 297
 298   return 1;
 299 }
 300
 301 static int
 302 mipsnbsd_cannot_fetch_register (int regno)
 303 {
 304   return (regno == MIPS_ZERO_REGNUM
 305           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 306 }
 307
 308 static int
 309 mipsnbsd_cannot_store_register (int regno)
 310 {
 311   return (regno == MIPS_ZERO_REGNUM
 312           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 313 }
 314
 315 /* Shared library support.  */
 316
 317 /* NetBSD/mips uses a slightly different `struct link_map' than the
 318    other NetBSD platforms.  */
 319
 320 static struct link_map_offsets *
 321 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 322 {
 323   static struct link_map_offsets lmo;
 324   static struct link_map_offsets *lmp = NULL;
 325
 326   if (lmp == NULL)
 327     {
 328       lmp = &lmo;
 329
 330       /* Everything we need is in the first 8 bytes.  */
 331       lmo.r_debug_size = 8;
 332       lmo.r_map_offset = 4;
 333       lmo.r_map_size   = 4;
 334
 335       /* Everything we need is in the first 24 bytes.  */
 336       lmo.link_map_size = 24;
 337       lmo.l_addr_offset = 4;
 338       lmo.l_addr_size   = 4;
 339       lmo.l_name_offset = 8;
 340       lmo.l_name_size   = 4;
 341       lmo.l_next_offset = 16;
 342       lmo.l_next_size   = 4;
 343       lmo.l_prev_offset = 20;
 344       lmo.l_prev_size   = 4;
 345     }
 346
 347   return lmp;
 348 }
 349
 350 static struct link_map_offsets *
 351 mipsnbsd_lp64_fetch_link_map_offsets (void)
 352 {
 353   static struct link_map_offsets lmo;
 354   static struct link_map_offsets *lmp = NULL;
 355
 356   if (lmp == NULL)
 357     {
 358       lmp = &lmo;
 359
 360       /* Everything we need is in the first 16 bytes.  */
 361       lmo.r_debug_size = 16;
 362       lmo.r_map_offset = 8;
 363       lmo.r_map_size   = 8;
 364
 365       /* Everything we need is in the first 40 bytes.  */
 366       lmo.link_map_size = 48;
 367       lmo.l_addr_offset = 0;
 368       lmo.l_addr_size   = 8;
 369       lmo.l_name_offset = 16;
 370       lmo.l_name_size   = 8;
 371       lmo.l_next_offset = 32;
 372       lmo.l_next_size   = 8;
 373       lmo.l_prev_offset = 40;
 374       lmo.l_prev_size   = 8;
 375     }
 376
 377   return lmp;
 378 }
 379 \f
 380
 381 static void
 382 mipsnbsd_init_abi (struct gdbarch_info info,
 383                    struct gdbarch *gdbarch)
 384 {
 385   set_gdbarch_regset_from_core_section
 386     (gdbarch, mipsnbsd_regset_from_core_section);
 387
 388   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 389
 390   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 391   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 392
 393   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 394
 395   /* NetBSD/mips has SVR4-style shared libraries.  */
 396   set_solib_svr4_fetch_link_map_offsets
 397     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 398                mipsnbsd_ilp32_fetch_link_map_offsets :
 399                mipsnbsd_lp64_fetch_link_map_offsets));
 400 }
 401 \f
 402
 403 static enum gdb_osabi
 404 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 405 {
 406   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 407     return GDB_OSABI_NETBSD_ELF;
 408
 409   return GDB_OSABI_UNKNOWN;
 410 }
 411
 412 void
 413 _initialize_mipsnbsd_tdep (void)
 414 {
 415   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 416                           mipsnbsd_init_abi);
 417 }