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 <= gdbarch_pc_regnum (current_gdbarch); 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 <= gdbarch_pc_regnum (current_gdbarch); 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 = gdbarch_fp0_regnum (current_gdbarch);
 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
 190                                  + ((i - gdbarch_fp0_regnum (current_gdbarch))
 191                                     * mips_isa_regsize (current_gdbarch)));
 192         }
 193     }
 194 }
 195
 196 void
 197 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 198 {
 199   int i;
 200
 201   for (i = gdbarch_fp0_regnum (current_gdbarch);
 202        i <= mips_regnum (current_gdbarch)->fp_control_status;
 203        i++)
 204     if ((regno == i || regno == -1)
 205         && ! gdbarch_cannot_store_register (current_gdbarch, i))
 206       regcache_raw_collect (regcache, i,
 207                             fpregs + ((i - gdbarch_fp0_regnum
 208                                              (current_gdbarch))
 209                               * mips_isa_regsize (current_gdbarch)));
 210 }
 211
 212 /* Under NetBSD/mips, signal handler invocations can be identified by the
 213    designated code sequence that is used to return from a signal handler.
 214    In particular, the return address of a signal handler points to the
 215    following code sequence:
 216
 217         addu    a0, sp, 16
 218         li      v0, 295                 # __sigreturn14
 219         syscall
 220
 221    Each instruction has a unique encoding, so we simply attempt to match
 222    the instruction the PC is pointing to with any of the above instructions.
 223    If there is a hit, we know the offset to the start of the designated
 224    sequence and can then check whether we really are executing in the
 225    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 226    start of the return sequence is returned.  */
 227
 228 #define RETCODE_NWORDS  3
 229 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 230
 231 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 232 {
 233   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 234   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 235   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 236 };
 237
 238 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 239 {
 240   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 241   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 242   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 243 };
 244
 245 static LONGEST
 246 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 247 {
 248   CORE_ADDR pc = frame_pc_unwind (next_frame);
 249   const char *retcode = gdbarch_byte_order (current_gdbarch)
 250                         == BFD_ENDIAN_BIG ? sigtramp_retcode_mipseb :
 251                         sigtramp_retcode_mipsel;
 252   unsigned char ret[RETCODE_SIZE], w[4];
 253   LONGEST off;
 254   int i;
 255
 256   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 257     return -1;
 258
 259   for (i = 0; i < RETCODE_NWORDS; i++)
 260     {
 261       if (memcmp (w, retcode + (i * 4), 4) == 0)
 262         break;
 263     }
 264   if (i == RETCODE_NWORDS)
 265     return -1;
 266
 267   off = i * 4;
 268   pc -= off;
 269
 270   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 271     return -1;
 272
 273   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 274     return off;
 275
 276   return -1;
 277 }
 278
 279 /* Figure out where the longjmp will land.  We expect that we have
 280    just entered longjmp and haven't yet setup the stack frame, so the
 281    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 282    jmp_buf structure from which we extract the PC that we will land
 283    at.  The PC is copied into *pc.  This routine returns true on
 284    success.  */
 285
 286 #define NBSD_MIPS_JB_PC                 (2 * 4)
 287 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 288 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 289                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 290
 291 static int
 292 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 293 {
 294   CORE_ADDR jb_addr;
 295   char *buf;
 296
 297   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 298
 299   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 300
 301   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 302                           NBSD_MIPS_JB_ELEMENT_SIZE))
 303     return 0;
 304
 305   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 306
 307   return 1;
 308 }
 309
 310 static int
 311 mipsnbsd_cannot_fetch_register (int regno)
 312 {
 313   return (regno == MIPS_ZERO_REGNUM
 314           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 315 }
 316
 317 static int
 318 mipsnbsd_cannot_store_register (int regno)
 319 {
 320   return (regno == MIPS_ZERO_REGNUM
 321           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 322 }
 323
 324 /* Shared library support.  */
 325
 326 /* NetBSD/mips uses a slightly different `struct link_map' than the
 327    other NetBSD platforms.  */
 328
 329 static struct link_map_offsets *
 330 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 331 {
 332   static struct link_map_offsets lmo;
 333   static struct link_map_offsets *lmp = NULL;
 334
 335   if (lmp == NULL)
 336     {
 337       lmp = &lmo;
 338
 339       lmo.r_version_offset = 0;
 340       lmo.r_version_size = 4;
 341       lmo.r_map_offset = 4;
 342       lmo.r_ldsomap_offset = -1;
 343
 344       /* Everything we need is in the first 24 bytes.  */
 345       lmo.link_map_size = 24;
 346       lmo.l_addr_offset = 4;
 347       lmo.l_name_offset = 8;
 348       lmo.l_ld_offset = 12;
 349       lmo.l_next_offset = 16;
 350       lmo.l_prev_offset = 20;
 351     }
 352
 353   return lmp;
 354 }
 355
 356 static struct link_map_offsets *
 357 mipsnbsd_lp64_fetch_link_map_offsets (void)
 358 {
 359   static struct link_map_offsets lmo;
 360   static struct link_map_offsets *lmp = NULL;
 361
 362   if (lmp == NULL)
 363     {
 364       lmp = &lmo;
 365
 366       lmo.r_version_offset = 0;
 367       lmo.r_version_size = 4;
 368       lmo.r_map_offset = 8;
 369       lmo.r_ldsomap_offset = -1;
 370
 371       /* Everything we need is in the first 40 bytes.  */
 372       lmo.link_map_size = 48;
 373       lmo.l_addr_offset = 0;
 374       lmo.l_name_offset = 16;
 375       lmo.l_ld_offset = 24;
 376       lmo.l_next_offset = 32;
 377       lmo.l_prev_offset = 40;
 378     }
 379
 380   return lmp;
 381 }
 382 \f
 383
 384 static void
 385 mipsnbsd_init_abi (struct gdbarch_info info,
 386                    struct gdbarch *gdbarch)
 387 {
 388   set_gdbarch_regset_from_core_section
 389     (gdbarch, mipsnbsd_regset_from_core_section);
 390
 391   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 392
 393   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 394   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 395
 396   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 397
 398   /* NetBSD/mips has SVR4-style shared libraries.  */
 399   set_solib_svr4_fetch_link_map_offsets
 400     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 401                mipsnbsd_ilp32_fetch_link_map_offsets :
 402                mipsnbsd_lp64_fetch_link_map_offsets));
 403 }
 404 \f
 405
 406 static enum gdb_osabi
 407 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 408 {
 409   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 410     return GDB_OSABI_NETBSD_ELF;
 411
 412   return GDB_OSABI_UNKNOWN;
 413 }
 414
 415 void
 416 _initialize_mipsnbsd_tdep (void)
 417 {
 418   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 419                           mipsnbsd_init_abi);
 420 }