gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002, 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
   4
   5    Contributed by Wasabi Systems, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, USA.  */
  23
  24 #include "defs.h"
  25 #include "gdbcore.h"
  26 #include "regcache.h"
  27 #include "regset.h"
  28 #include "target.h"
  29 #include "value.h"
  30 #include "osabi.h"
  31
  32 #include "gdb_assert.h"
  33 #include "gdb_string.h"
  34
  35 #include "nbsd-tdep.h"
  36 #include "mipsnbsd-tdep.h"
  37 #include "mips-tdep.h"
  38
  39 #include "solib-svr4.h"
  40
  41 /* Shorthand for some register numbers used below.  */
  42 #define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
  43 #define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
  44 #define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
  45
  46 /* Core file support.  */
  47
  48 /* Number of registers in `struct reg' from <machine/reg.h>.  */
  49 #define MIPSNBSD_NUM_GREGS      38
  50
  51 /* Number of registers in `struct fpreg' from <machine/reg.h>.  */
  52 #define MIPSNBSD_NUM_FPREGS     33
  53
  54 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  55    in the floating-point register set REGSET to register cache
  56    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  57
  58 static void
  59 mipsnbsd_supply_fpregset (const struct regset *regset,
  60                           struct regcache *regcache,
  61                           int regnum, const void *fpregs, size_t len)
  62 {
  63   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  64   const char *regs = fpregs;
  65   int i;
  66
  67   gdb_assert (len >= MIPSNBSD_NUM_FPREGS * regsize);
  68
  69   for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
  70     {
  71       if (regnum == i || regnum == -1)
  72         regcache_raw_supply (regcache, i,
  73                              regs + (i - MIPS_FP0_REGNUM) * regsize);
  74     }
  75 }
  76
  77 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  78    in the general-purpose register set REGSET to register cache
  79    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  80
  81 static void
  82 mipsnbsd_supply_gregset (const struct regset *regset,
  83                          struct regcache *regcache, int regnum,
  84                          const void *gregs, size_t len)
  85 {
  86   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  87   const char *regs = gregs;
  88   int i;
  89
  90   gdb_assert (len >= MIPSNBSD_NUM_GREGS * regsize);
  91
  92   for (i = 0; i <= MIPS_PC_REGNUM; i++)
  93     {
  94       if (regnum == i || regnum == -1)
  95         regcache_raw_supply (regcache, i, regs + i * regsize);
  96     }
  97
  98   if (len >= (MIPSNBSD_NUM_GREGS + MIPSNBSD_NUM_FPREGS) * regsize)
  99     {
 100       regs += MIPSNBSD_NUM_GREGS * regsize;
 101       len -= MIPSNBSD_NUM_GREGS * regsize;
 102       mipsnbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 103     }
 104 }
 105
 106 /* NetBSD/mips register sets.  */
 107
 108 static struct regset mipsnbsd_gregset =
 109 {
 110   NULL,
 111   mipsnbsd_supply_gregset
 112 };
 113
 114 static struct regset mipsnbsd_fpregset =
 115 {
 116   NULL,
 117   mipsnbsd_supply_fpregset
 118 };
 119
 120 /* Return the appropriate register set for the core section identified
 121    by SECT_NAME and SECT_SIZE.  */
 122
 123 static const struct regset *
 124 mipsnbsd_regset_from_core_section (struct gdbarch *gdbarch,
 125                                    const char *sect_name, size_t sect_size)
 126 {
 127   size_t regsize = mips_isa_regsize (gdbarch);
 128
 129   if (strcmp (sect_name, ".reg") == 0
 130       && sect_size >= MIPSNBSD_NUM_GREGS * regsize)
 131     return &mipsnbsd_gregset;
 132
 133   if (strcmp (sect_name, ".reg2") == 0
 134       && sect_size >= MIPSNBSD_NUM_FPREGS * regsize)
 135     return &mipsnbsd_fpregset;
 136
 137   return NULL;
 138 }
 139 \f
 140
 141 /* Conveniently, GDB uses the same register numbering as the
 142    ptrace register structure used by NetBSD/mips.  */
 143
 144 void
 145 mipsnbsd_supply_reg (struct regcache *regcache, const char *regs, int regno)
 146 {
 147   int i;
 148
 149   for (i = 0; i <= PC_REGNUM; i++)
 150     {
 151       if (regno == i || regno == -1)
 152         {
 153           if (gdbarch_cannot_fetch_register (current_gdbarch, i))
 154             regcache_raw_supply (regcache, i, NULL);
 155           else
 156             regcache_raw_supply (regcache, i,
 157                                  regs + (i * mips_isa_regsize (current_gdbarch)));
 158         }
 159     }
 160 }
 161
 162 void
 163 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 164 {
 165   int i;
 166
 167   for (i = 0; i <= PC_REGNUM; i++)
 168     if ((regno == i || regno == -1)
 169         && ! gdbarch_cannot_store_register (current_gdbarch, i))
 170       regcache_raw_collect (regcache, i,
 171                             regs + (i * mips_isa_regsize (current_gdbarch)));
 172 }
 173
 174 void
 175 mipsnbsd_supply_fpreg (struct regcache *regcache, const char *fpregs, int regno)
 176 {
 177   int i;
 178
 179   for (i = FP0_REGNUM;
 180        i <= mips_regnum (current_gdbarch)->fp_implementation_revision;
 181        i++)
 182     {
 183       if (regno == i || regno == -1)
 184         {
 185           if (gdbarch_cannot_fetch_register (current_gdbarch, i))
 186             regcache_raw_supply (regcache, i, NULL);
 187           else
 188             regcache_raw_supply (regcache, i,
 189                                  fpregs + ((i - FP0_REGNUM) * mips_isa_regsize (current_gdbarch)));
 190         }
 191     }
 192 }
 193
 194 void
 195 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 196 {
 197   int i;
 198
 199   for (i = FP0_REGNUM; i <= mips_regnum (current_gdbarch)->fp_control_status;
 200        i++)
 201     if ((regno == i || regno == -1)
 202         && ! gdbarch_cannot_store_register (current_gdbarch, i))
 203       regcache_raw_collect (regcache, i,
 204                             fpregs + ((i - FP0_REGNUM) * mips_isa_regsize (current_gdbarch)));
 205 }
 206
 207 /* Under NetBSD/mips, signal handler invocations can be identified by the
 208    designated code sequence that is used to return from a signal handler.
 209    In particular, the return address of a signal handler points to the
 210    following code sequence:
 211
 212         addu    a0, sp, 16
 213         li      v0, 295                 # __sigreturn14
 214         syscall
 215
 216    Each instruction has a unique encoding, so we simply attempt to match
 217    the instruction the PC is pointing to with any of the above instructions.
 218    If there is a hit, we know the offset to the start of the designated
 219    sequence and can then check whether we really are executing in the
 220    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 221    start of the return sequence is returned.  */
 222
 223 #define RETCODE_NWORDS  3
 224 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 225
 226 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 227 {
 228   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 229   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 230   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 231 };
 232
 233 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 234 {
 235   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 236   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 237   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 238 };
 239
 240 static LONGEST
 241 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 242 {
 243   CORE_ADDR pc = frame_pc_unwind (next_frame);
 244   const char *retcode = TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
 245         ? sigtramp_retcode_mipseb : sigtramp_retcode_mipsel;
 246   unsigned char ret[RETCODE_SIZE], w[4];
 247   LONGEST off;
 248   int i;
 249
 250   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 251     return -1;
 252
 253   for (i = 0; i < RETCODE_NWORDS; i++)
 254     {
 255       if (memcmp (w, retcode + (i * 4), 4) == 0)
 256         break;
 257     }
 258   if (i == RETCODE_NWORDS)
 259     return -1;
 260
 261   off = i * 4;
 262   pc -= off;
 263
 264   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 265     return -1;
 266
 267   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 268     return off;
 269
 270   return -1;
 271 }
 272
 273 /* Figure out where the longjmp will land.  We expect that we have
 274    just entered longjmp and haven't yet setup the stack frame, so the
 275    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 276    jmp_buf structure from which we extract the PC that we will land
 277    at.  The PC is copied into *pc.  This routine returns true on
 278    success.  */
 279
 280 #define NBSD_MIPS_JB_PC                 (2 * 4)
 281 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 282 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 283                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 284
 285 static int
 286 mipsnbsd_get_longjmp_target (CORE_ADDR *pc)
 287 {
 288   CORE_ADDR jb_addr;
 289   char *buf;
 290
 291   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 292
 293   jb_addr = read_register (MIPS_A0_REGNUM);
 294
 295   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 296                           NBSD_MIPS_JB_ELEMENT_SIZE))
 297     return 0;
 298
 299   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 300
 301   return 1;
 302 }
 303
 304 static int
 305 mipsnbsd_cannot_fetch_register (int regno)
 306 {
 307   return (regno == MIPS_ZERO_REGNUM
 308           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 309 }
 310
 311 static int
 312 mipsnbsd_cannot_store_register (int regno)
 313 {
 314   return (regno == MIPS_ZERO_REGNUM
 315           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 316 }
 317
 318 /* Shared library support.  */
 319
 320 /* NetBSD/mips uses a slightly different `struct link_map' than the
 321    other NetBSD platforms.  */
 322
 323 static struct link_map_offsets *
 324 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 325 {
 326   static struct link_map_offsets lmo;
 327   static struct link_map_offsets *lmp = NULL;
 328
 329   if (lmp == NULL)
 330     {
 331       lmp = &lmo;
 332
 333       lmo.r_version_offset = 0;
 334       lmo.r_version_size = 4;
 335       lmo.r_map_offset = 4;
 336       lmo.r_ldsomap_offset = -1;
 337
 338       /* Everything we need is in the first 24 bytes.  */
 339       lmo.link_map_size = 24;
 340       lmo.l_addr_offset = 4;
 341       lmo.l_name_offset = 8;
 342       lmo.l_ld_offset = 12;
 343       lmo.l_next_offset = 16;
 344       lmo.l_prev_offset = 20;
 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       lmo.r_version_offset = 0;
 361       lmo.r_version_size = 4;
 362       lmo.r_map_offset = 8;
 363       lmo.r_ldsomap_offset = -1;
 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_name_offset = 16;
 369       lmo.l_ld_offset = 24;
 370       lmo.l_next_offset = 32;
 371       lmo.l_prev_offset = 40;
 372     }
 373
 374   return lmp;
 375 }
 376 \f
 377
 378 static void
 379 mipsnbsd_init_abi (struct gdbarch_info info,
 380                    struct gdbarch *gdbarch)
 381 {
 382   set_gdbarch_regset_from_core_section
 383     (gdbarch, mipsnbsd_regset_from_core_section);
 384
 385   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 386
 387   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 388   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 389
 390   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 391
 392   /* NetBSD/mips has SVR4-style shared libraries.  */
 393   set_solib_svr4_fetch_link_map_offsets
 394     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 395                mipsnbsd_ilp32_fetch_link_map_offsets :
 396                mipsnbsd_lp64_fetch_link_map_offsets));
 397 }
 398 \f
 399
 400 static enum gdb_osabi
 401 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 402 {
 403   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 404     return GDB_OSABI_NETBSD_ELF;
 405
 406   return GDB_OSABI_UNKNOWN;
 407 }
 408
 409 void
 410 _initialize_mipsnbsd_tdep (void)
 411 {
 412   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 413                           mipsnbsd_init_abi);
 414 }