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   int i;
 146
 147   for (i = 0; i <= gdbarch_pc_regnum (current_gdbarch); i++)
 148     {
 149       if (regno == i || regno == -1)
 150         {
 151           if (gdbarch_cannot_fetch_register (current_gdbarch, i))
 152             regcache_raw_supply (regcache, i, NULL);
 153           else
 154             regcache_raw_supply (regcache, i,
 155                                  regs + (i * mips_isa_regsize (current_gdbarch)));
 156         }
 157     }
 158 }
 159
 160 void
 161 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 162 {
 163   int i;
 164
 165   for (i = 0; i <= gdbarch_pc_regnum (current_gdbarch); i++)
 166     if ((regno == i || regno == -1)
 167         && ! gdbarch_cannot_store_register (current_gdbarch, i))
 168       regcache_raw_collect (regcache, i,
 169                             regs + (i * mips_isa_regsize (current_gdbarch)));
 170 }
 171
 172 void
 173 mipsnbsd_supply_fpreg (struct regcache *regcache, const char *fpregs, int regno)
 174 {
 175   int i;
 176
 177   for (i = gdbarch_fp0_regnum (current_gdbarch);
 178        i <= mips_regnum (current_gdbarch)->fp_implementation_revision;
 179        i++)
 180     {
 181       if (regno == i || regno == -1)
 182         {
 183           if (gdbarch_cannot_fetch_register (current_gdbarch, i))
 184             regcache_raw_supply (regcache, i, NULL);
 185           else
 186             regcache_raw_supply (regcache, i,
 187                                  fpregs
 188                                  + ((i - gdbarch_fp0_regnum (current_gdbarch))
 189                                     * 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 = gdbarch_fp0_regnum (current_gdbarch);
 200        i <= mips_regnum (current_gdbarch)->fp_control_status;
 201        i++)
 202     if ((regno == i || regno == -1)
 203         && ! gdbarch_cannot_store_register (current_gdbarch, i))
 204       regcache_raw_collect (regcache, i,
 205                             fpregs + ((i - gdbarch_fp0_regnum
 206                                              (current_gdbarch))
 207                               * mips_isa_regsize (current_gdbarch)));
 208 }
 209
 210 /* Under NetBSD/mips, signal handler invocations can be identified by the
 211    designated code sequence that is used to return from a signal handler.
 212    In particular, the return address of a signal handler points to the
 213    following code sequence:
 214
 215         addu    a0, sp, 16
 216         li      v0, 295                 # __sigreturn14
 217         syscall
 218
 219    Each instruction has a unique encoding, so we simply attempt to match
 220    the instruction the PC is pointing to with any of the above instructions.
 221    If there is a hit, we know the offset to the start of the designated
 222    sequence and can then check whether we really are executing in the
 223    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 224    start of the return sequence is returned.  */
 225
 226 #define RETCODE_NWORDS  3
 227 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 228
 229 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 230 {
 231   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 232   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 233   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 234 };
 235
 236 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 237 {
 238   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 239   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 240   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 241 };
 242
 243 static LONGEST
 244 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 245 {
 246   CORE_ADDR pc = frame_pc_unwind (next_frame);
 247   const char *retcode = gdbarch_byte_order (current_gdbarch)
 248                         == BFD_ENDIAN_BIG ? sigtramp_retcode_mipseb :
 249                         sigtramp_retcode_mipsel;
 250   unsigned char ret[RETCODE_SIZE], w[4];
 251   LONGEST off;
 252   int i;
 253
 254   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 255     return -1;
 256
 257   for (i = 0; i < RETCODE_NWORDS; i++)
 258     {
 259       if (memcmp (w, retcode + (i * 4), 4) == 0)
 260         break;
 261     }
 262   if (i == RETCODE_NWORDS)
 263     return -1;
 264
 265   off = i * 4;
 266   pc -= off;
 267
 268   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 269     return -1;
 270
 271   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 272     return off;
 273
 274   return -1;
 275 }
 276
 277 /* Figure out where the longjmp will land.  We expect that we have
 278    just entered longjmp and haven't yet setup the stack frame, so the
 279    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 280    jmp_buf structure from which we extract the PC that we will land
 281    at.  The PC is copied into *pc.  This routine returns true on
 282    success.  */
 283
 284 #define NBSD_MIPS_JB_PC                 (2 * 4)
 285 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 286 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 287                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 288
 289 static int
 290 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 291 {
 292   CORE_ADDR jb_addr;
 293   char *buf;
 294
 295   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 296
 297   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 298
 299   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 300                           NBSD_MIPS_JB_ELEMENT_SIZE))
 301     return 0;
 302
 303   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 304
 305   return 1;
 306 }
 307
 308 static int
 309 mipsnbsd_cannot_fetch_register (int regno)
 310 {
 311   return (regno == MIPS_ZERO_REGNUM
 312           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 313 }
 314
 315 static int
 316 mipsnbsd_cannot_store_register (int regno)
 317 {
 318   return (regno == MIPS_ZERO_REGNUM
 319           || regno == mips_regnum (current_gdbarch)->fp_implementation_revision);
 320 }
 321
 322 /* Shared library support.  */
 323
 324 /* NetBSD/mips uses a slightly different `struct link_map' than the
 325    other NetBSD platforms.  */
 326
 327 static struct link_map_offsets *
 328 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 329 {
 330   static struct link_map_offsets lmo;
 331   static struct link_map_offsets *lmp = NULL;
 332
 333   if (lmp == NULL)
 334     {
 335       lmp = &lmo;
 336
 337       lmo.r_version_offset = 0;
 338       lmo.r_version_size = 4;
 339       lmo.r_map_offset = 4;
 340       lmo.r_ldsomap_offset = -1;
 341
 342       /* Everything we need is in the first 24 bytes.  */
 343       lmo.link_map_size = 24;
 344       lmo.l_addr_offset = 4;
 345       lmo.l_name_offset = 8;
 346       lmo.l_ld_offset = 12;
 347       lmo.l_next_offset = 16;
 348       lmo.l_prev_offset = 20;
 349     }
 350
 351   return lmp;
 352 }
 353
 354 static struct link_map_offsets *
 355 mipsnbsd_lp64_fetch_link_map_offsets (void)
 356 {
 357   static struct link_map_offsets lmo;
 358   static struct link_map_offsets *lmp = NULL;
 359
 360   if (lmp == NULL)
 361     {
 362       lmp = &lmo;
 363
 364       lmo.r_version_offset = 0;
 365       lmo.r_version_size = 4;
 366       lmo.r_map_offset = 8;
 367       lmo.r_ldsomap_offset = -1;
 368
 369       /* Everything we need is in the first 40 bytes.  */
 370       lmo.link_map_size = 48;
 371       lmo.l_addr_offset = 0;
 372       lmo.l_name_offset = 16;
 373       lmo.l_ld_offset = 24;
 374       lmo.l_next_offset = 32;
 375       lmo.l_prev_offset = 40;
 376     }
 377
 378   return lmp;
 379 }
 380 \f
 381
 382 static void
 383 mipsnbsd_init_abi (struct gdbarch_info info,
 384                    struct gdbarch *gdbarch)
 385 {
 386   set_gdbarch_regset_from_core_section
 387     (gdbarch, mipsnbsd_regset_from_core_section);
 388
 389   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 390
 391   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 392   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 393
 394   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 395
 396   /* NetBSD/mips has SVR4-style shared libraries.  */
 397   set_solib_svr4_fetch_link_map_offsets
 398     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 399                mipsnbsd_ilp32_fetch_link_map_offsets :
 400                mipsnbsd_lp64_fetch_link_map_offsets));
 401 }
 402 \f
 403
 404 static enum gdb_osabi
 405 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 406 {
 407   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 408     return GDB_OSABI_NETBSD_ELF;
 409
 410   return GDB_OSABI_UNKNOWN;
 411 }
 412
 413 void
 414 _initialize_mipsnbsd_tdep (void)
 415 {
 416   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 417                           mipsnbsd_init_abi);
 418 }