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 3 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, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25 #include "regset.h"
  26 #include "target.h"
  27 #include "value.h"
  28 #include "osabi.h"
  29
  30 #include "gdb_assert.h"
  31 #include "gdb_string.h"
  32
  33 #include "nbsd-tdep.h"
  34 #include "mipsnbsd-tdep.h"
  35 #include "mips-tdep.h"
  36
  37 #include "solib-svr4.h"
  38
  39 /* Shorthand for some register numbers used below.  */
  40 #define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
  41 #define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
  42 #define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
  43
  44 /* Core file support.  */
  45
  46 /* Number of registers in `struct reg' from <machine/reg.h>.  */
  47 #define MIPSNBSD_NUM_GREGS      38
  48
  49 /* Number of registers in `struct fpreg' from <machine/reg.h>.  */
  50 #define MIPSNBSD_NUM_FPREGS     33
  51
  52 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  53    in the floating-point register set REGSET to register cache
  54    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  55
  56 static void
  57 mipsnbsd_supply_fpregset (const struct regset *regset,
  58                           struct regcache *regcache,
  59                           int regnum, const void *fpregs, size_t len)
  60 {
  61   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  62   const char *regs = fpregs;
  63   int i;
  64
  65   gdb_assert (len >= MIPSNBSD_NUM_FPREGS * regsize);
  66
  67   for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
  68     {
  69       if (regnum == i || regnum == -1)
  70         regcache_raw_supply (regcache, i,
  71                              regs + (i - MIPS_FP0_REGNUM) * regsize);
  72     }
  73 }
  74
  75 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  76    in the general-purpose register set REGSET to register cache
  77    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  78
  79 static void
  80 mipsnbsd_supply_gregset (const struct regset *regset,
  81                          struct regcache *regcache, int regnum,
  82                          const void *gregs, size_t len)
  83 {
  84   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  85   const char *regs = gregs;
  86   int i;
  87
  88   gdb_assert (len >= MIPSNBSD_NUM_GREGS * regsize);
  89
  90   for (i = 0; i <= MIPS_PC_REGNUM; i++)
  91     {
  92       if (regnum == i || regnum == -1)
  93         regcache_raw_supply (regcache, i, regs + i * regsize);
  94     }
  95
  96   if (len >= (MIPSNBSD_NUM_GREGS + MIPSNBSD_NUM_FPREGS) * regsize)
  97     {
  98       regs += MIPSNBSD_NUM_GREGS * regsize;
  99       len -= MIPSNBSD_NUM_GREGS * regsize;
 100       mipsnbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 101     }
 102 }
 103
 104 /* NetBSD/mips register sets.  */
 105
 106 static struct regset mipsnbsd_gregset =
 107 {
 108   NULL,
 109   mipsnbsd_supply_gregset
 110 };
 111
 112 static struct regset mipsnbsd_fpregset =
 113 {
 114   NULL,
 115   mipsnbsd_supply_fpregset
 116 };
 117
 118 /* Return the appropriate register set for the core section identified
 119    by SECT_NAME and SECT_SIZE.  */
 120
 121 static const struct regset *
 122 mipsnbsd_regset_from_core_section (struct gdbarch *gdbarch,
 123                                    const char *sect_name, size_t sect_size)
 124 {
 125   size_t regsize = mips_isa_regsize (gdbarch);
 126
 127   if (strcmp (sect_name, ".reg") == 0
 128       && sect_size >= MIPSNBSD_NUM_GREGS * regsize)
 129     return &mipsnbsd_gregset;
 130
 131   if (strcmp (sect_name, ".reg2") == 0
 132       && sect_size >= MIPSNBSD_NUM_FPREGS * regsize)
 133     return &mipsnbsd_fpregset;
 134
 135   return NULL;
 136 }
 137 \f
 138
 139 /* Conveniently, GDB uses the same register numbering as the
 140    ptrace register structure used by NetBSD/mips.  */
 141
 142 void
 143 mipsnbsd_supply_reg (struct regcache *regcache, const char *regs, int regno)
 144 {
 145   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 146   int i;
 147
 148   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 149     {
 150       if (regno == i || regno == -1)
 151         {
 152           if (gdbarch_cannot_fetch_register (gdbarch, i))
 153             regcache_raw_supply (regcache, i, NULL);
 154           else
 155             regcache_raw_supply (regcache, i,
 156                                  regs + (i * mips_isa_regsize (gdbarch)));
 157         }
 158     }
 159 }
 160
 161 void
 162 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 163 {
 164   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 165   int i;
 166
 167   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 168     if ((regno == i || regno == -1)
 169         && ! gdbarch_cannot_store_register (gdbarch, i))
 170       regcache_raw_collect (regcache, i,
 171                             regs + (i * mips_isa_regsize (gdbarch)));
 172 }
 173
 174 void
 175 mipsnbsd_supply_fpreg (struct regcache *regcache, const char *fpregs, int regno)
 176 {
 177   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 178   int i;
 179
 180   for (i = gdbarch_fp0_regnum (gdbarch);
 181        i <= mips_regnum (gdbarch)->fp_implementation_revision;
 182        i++)
 183     {
 184       if (regno == i || regno == -1)
 185         {
 186           if (gdbarch_cannot_fetch_register (gdbarch, i))
 187             regcache_raw_supply (regcache, i, NULL);
 188           else
 189             regcache_raw_supply (regcache, i,
 190                                  fpregs
 191                                  + ((i - gdbarch_fp0_regnum (gdbarch))
 192                                     * mips_isa_regsize (gdbarch)));
 193         }
 194     }
 195 }
 196
 197 void
 198 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 199 {
 200   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 201   int i;
 202
 203   for (i = gdbarch_fp0_regnum (gdbarch);
 204        i <= mips_regnum (gdbarch)->fp_control_status;
 205        i++)
 206     if ((regno == i || regno == -1)
 207         && ! gdbarch_cannot_store_register (gdbarch, i))
 208       regcache_raw_collect (regcache, i,
 209                             fpregs + ((i - gdbarch_fp0_regnum (gdbarch))
 210                               * mips_isa_regsize (gdbarch)));
 211 }
 212
 213 /* Under NetBSD/mips, signal handler invocations can be identified by the
 214    designated code sequence that is used to return from a signal handler.
 215    In particular, the return address of a signal handler points to the
 216    following code sequence:
 217
 218         addu    a0, sp, 16
 219         li      v0, 295                 # __sigreturn14
 220         syscall
 221
 222    Each instruction has a unique encoding, so we simply attempt to match
 223    the instruction the PC is pointing to with any of the above instructions.
 224    If there is a hit, we know the offset to the start of the designated
 225    sequence and can then check whether we really are executing in the
 226    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 227    start of the return sequence is returned.  */
 228
 229 #define RETCODE_NWORDS  3
 230 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 231
 232 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 233 {
 234   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 235   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 236   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 237 };
 238
 239 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 240 {
 241   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 242   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 243   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 244 };
 245
 246 static LONGEST
 247 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 248 {
 249   CORE_ADDR pc = frame_pc_unwind (next_frame);
 250   const char *retcode = gdbarch_byte_order (get_frame_arch (next_frame))
 251                         == BFD_ENDIAN_BIG ? sigtramp_retcode_mipseb :
 252                         sigtramp_retcode_mipsel;
 253   unsigned char ret[RETCODE_SIZE], w[4];
 254   LONGEST off;
 255   int i;
 256
 257   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 258     return -1;
 259
 260   for (i = 0; i < RETCODE_NWORDS; i++)
 261     {
 262       if (memcmp (w, retcode + (i * 4), 4) == 0)
 263         break;
 264     }
 265   if (i == RETCODE_NWORDS)
 266     return -1;
 267
 268   off = i * 4;
 269   pc -= off;
 270
 271   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 272     return -1;
 273
 274   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 275     return off;
 276
 277   return -1;
 278 }
 279
 280 /* Figure out where the longjmp will land.  We expect that we have
 281    just entered longjmp and haven't yet setup the stack frame, so the
 282    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 283    jmp_buf structure from which we extract the PC that we will land
 284    at.  The PC is copied into *pc.  This routine returns true on
 285    success.  */
 286
 287 #define NBSD_MIPS_JB_PC                 (2 * 4)
 288 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 289 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 290                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 291
 292 static int
 293 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 294 {
 295   CORE_ADDR jb_addr;
 296   char *buf;
 297
 298   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 299
 300   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 301
 302   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 303                           NBSD_MIPS_JB_ELEMENT_SIZE))
 304     return 0;
 305
 306   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 307
 308   return 1;
 309 }
 310
 311 static int
 312 mipsnbsd_cannot_fetch_register (int regno)
 313 {
 314   return (regno == MIPS_ZERO_REGNUM
 315           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 316 }
 317
 318 static int
 319 mipsnbsd_cannot_store_register (int regno)
 320 {
 321   return (regno == MIPS_ZERO_REGNUM
 322           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 323 }
 324
 325 /* Shared library support.  */
 326
 327 /* NetBSD/mips uses a slightly different `struct link_map' than the
 328    other NetBSD platforms.  */
 329
 330 static struct link_map_offsets *
 331 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 332 {
 333   static struct link_map_offsets lmo;
 334   static struct link_map_offsets *lmp = NULL;
 335
 336   if (lmp == NULL)
 337     {
 338       lmp = &lmo;
 339
 340       lmo.r_version_offset = 0;
 341       lmo.r_version_size = 4;
 342       lmo.r_map_offset = 4;
 343       lmo.r_ldsomap_offset = -1;
 344
 345       /* Everything we need is in the first 24 bytes.  */
 346       lmo.link_map_size = 24;
 347       lmo.l_addr_offset = 4;
 348       lmo.l_name_offset = 8;
 349       lmo.l_ld_offset = 12;
 350       lmo.l_next_offset = 16;
 351       lmo.l_prev_offset = 20;
 352     }
 353
 354   return lmp;
 355 }
 356
 357 static struct link_map_offsets *
 358 mipsnbsd_lp64_fetch_link_map_offsets (void)
 359 {
 360   static struct link_map_offsets lmo;
 361   static struct link_map_offsets *lmp = NULL;
 362
 363   if (lmp == NULL)
 364     {
 365       lmp = &lmo;
 366
 367       lmo.r_version_offset = 0;
 368       lmo.r_version_size = 4;
 369       lmo.r_map_offset = 8;
 370       lmo.r_ldsomap_offset = -1;
 371
 372       /* Everything we need is in the first 40 bytes.  */
 373       lmo.link_map_size = 48;
 374       lmo.l_addr_offset = 0;
 375       lmo.l_name_offset = 16;
 376       lmo.l_ld_offset = 24;
 377       lmo.l_next_offset = 32;
 378       lmo.l_prev_offset = 40;
 379     }
 380
 381   return lmp;
 382 }
 383 \f
 384
 385 static void
 386 mipsnbsd_init_abi (struct gdbarch_info info,
 387                    struct gdbarch *gdbarch)
 388 {
 389   set_gdbarch_regset_from_core_section
 390     (gdbarch, mipsnbsd_regset_from_core_section);
 391
 392   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 393
 394   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 395   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 396
 397   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 398
 399   /* NetBSD/mips has SVR4-style shared libraries.  */
 400   set_solib_svr4_fetch_link_map_offsets
 401     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 402                mipsnbsd_ilp32_fetch_link_map_offsets :
 403                mipsnbsd_lp64_fetch_link_map_offsets));
 404 }
 405 \f
 406
 407 static enum gdb_osabi
 408 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 409 {
 410   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 411     return GDB_OSABI_NETBSD_ELF;
 412
 413   return GDB_OSABI_UNKNOWN;
 414 }
 415
 416 void
 417 _initialize_mipsnbsd_tdep (void)
 418 {
 419   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 420                           mipsnbsd_init_abi);
 421 }