gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002, 2003, 2004, 2006, 2007, 2008
   4    Free Software Foundation, Inc.
   5
   6    Contributed by Wasabi Systems, Inc.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  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 (struct regcache *regcache, const char *regs, int regno)
 145 {
 146   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 147   int i;
 148
 149   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 150     {
 151       if (regno == i || regno == -1)
 152         {
 153           if (gdbarch_cannot_fetch_register (gdbarch, i))
 154             regcache_raw_supply (regcache, i, NULL);
 155           else
 156             regcache_raw_supply (regcache, i,
 157                                  regs + (i * mips_isa_regsize (gdbarch)));
 158         }
 159     }
 160 }
 161
 162 void
 163 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 164 {
 165   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 166   int i;
 167
 168   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 169     if ((regno == i || regno == -1)
 170         && ! gdbarch_cannot_store_register (gdbarch, i))
 171       regcache_raw_collect (regcache, i,
 172                             regs + (i * mips_isa_regsize (gdbarch)));
 173 }
 174
 175 void
 176 mipsnbsd_supply_fpreg (struct regcache *regcache, const char *fpregs, int regno)
 177 {
 178   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 179   int i;
 180
 181   for (i = gdbarch_fp0_regnum (gdbarch);
 182        i <= mips_regnum (gdbarch)->fp_implementation_revision;
 183        i++)
 184     {
 185       if (regno == i || regno == -1)
 186         {
 187           if (gdbarch_cannot_fetch_register (gdbarch, i))
 188             regcache_raw_supply (regcache, i, NULL);
 189           else
 190             regcache_raw_supply (regcache, i,
 191                                  fpregs
 192                                  + ((i - gdbarch_fp0_regnum (gdbarch))
 193                                     * mips_isa_regsize (gdbarch)));
 194         }
 195     }
 196 }
 197
 198 void
 199 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 200 {
 201   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 202   int i;
 203
 204   for (i = gdbarch_fp0_regnum (gdbarch);
 205        i <= mips_regnum (gdbarch)->fp_control_status;
 206        i++)
 207     if ((regno == i || regno == -1)
 208         && ! gdbarch_cannot_store_register (gdbarch, i))
 209       regcache_raw_collect (regcache, i,
 210                             fpregs + ((i - gdbarch_fp0_regnum (gdbarch))
 211                               * mips_isa_regsize (gdbarch)));
 212 }
 213
 214 /* Under NetBSD/mips, signal handler invocations can be identified by the
 215    designated code sequence that is used to return from a signal handler.
 216    In particular, the return address of a signal handler points to the
 217    following code sequence:
 218
 219         addu    a0, sp, 16
 220         li      v0, 295                 # __sigreturn14
 221         syscall
 222
 223    Each instruction has a unique encoding, so we simply attempt to match
 224    the instruction the PC is pointing to with any of the above instructions.
 225    If there is a hit, we know the offset to the start of the designated
 226    sequence and can then check whether we really are executing in the
 227    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 228    start of the return sequence is returned.  */
 229
 230 #define RETCODE_NWORDS  3
 231 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 232
 233 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 234 {
 235   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 236   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 237   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 238 };
 239
 240 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 241 {
 242   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 243   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 244   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 245 };
 246
 247 static LONGEST
 248 mipsnbsd_sigtramp_offset (struct frame_info *next_frame)
 249 {
 250   CORE_ADDR pc = frame_pc_unwind (next_frame);
 251   const char *retcode = gdbarch_byte_order (get_frame_arch (next_frame))
 252                         == BFD_ENDIAN_BIG ? sigtramp_retcode_mipseb :
 253                         sigtramp_retcode_mipsel;
 254   unsigned char ret[RETCODE_SIZE], w[4];
 255   LONGEST off;
 256   int i;
 257
 258   if (!safe_frame_unwind_memory (next_frame, pc, w, sizeof (w)))
 259     return -1;
 260
 261   for (i = 0; i < RETCODE_NWORDS; i++)
 262     {
 263       if (memcmp (w, retcode + (i * 4), 4) == 0)
 264         break;
 265     }
 266   if (i == RETCODE_NWORDS)
 267     return -1;
 268
 269   off = i * 4;
 270   pc -= off;
 271
 272   if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
 273     return -1;
 274
 275   if (memcmp (ret, retcode, RETCODE_SIZE) == 0)
 276     return off;
 277
 278   return -1;
 279 }
 280
 281 /* Figure out where the longjmp will land.  We expect that we have
 282    just entered longjmp and haven't yet setup the stack frame, so the
 283    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 284    jmp_buf structure from which we extract the PC that we will land
 285    at.  The PC is copied into *pc.  This routine returns true on
 286    success.  */
 287
 288 #define NBSD_MIPS_JB_PC                 (2 * 4)
 289 #define NBSD_MIPS_JB_ELEMENT_SIZE       mips_isa_regsize (current_gdbarch)
 290 #define NBSD_MIPS_JB_OFFSET             (NBSD_MIPS_JB_PC * \
 291                                          NBSD_MIPS_JB_ELEMENT_SIZE)
 292
 293 static int
 294 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 295 {
 296   CORE_ADDR jb_addr;
 297   char *buf;
 298
 299   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE);
 300
 301   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 302
 303   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET, buf,
 304                           NBSD_MIPS_JB_ELEMENT_SIZE))
 305     return 0;
 306
 307   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE);
 308
 309   return 1;
 310 }
 311
 312 static int
 313 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 314 {
 315   return (regno == MIPS_ZERO_REGNUM
 316           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 317 }
 318
 319 static int
 320 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 321 {
 322   return (regno == MIPS_ZERO_REGNUM
 323           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 324 }
 325
 326 /* Shared library support.  */
 327
 328 /* NetBSD/mips uses a slightly different `struct link_map' than the
 329    other NetBSD platforms.  */
 330
 331 static struct link_map_offsets *
 332 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 333 {
 334   static struct link_map_offsets lmo;
 335   static struct link_map_offsets *lmp = NULL;
 336
 337   if (lmp == NULL)
 338     {
 339       lmp = &lmo;
 340
 341       lmo.r_version_offset = 0;
 342       lmo.r_version_size = 4;
 343       lmo.r_map_offset = 4;
 344       lmo.r_ldsomap_offset = -1;
 345
 346       /* Everything we need is in the first 24 bytes.  */
 347       lmo.link_map_size = 24;
 348       lmo.l_addr_offset = 4;
 349       lmo.l_name_offset = 8;
 350       lmo.l_ld_offset = 12;
 351       lmo.l_next_offset = 16;
 352       lmo.l_prev_offset = 20;
 353     }
 354
 355   return lmp;
 356 }
 357
 358 static struct link_map_offsets *
 359 mipsnbsd_lp64_fetch_link_map_offsets (void)
 360 {
 361   static struct link_map_offsets lmo;
 362   static struct link_map_offsets *lmp = NULL;
 363
 364   if (lmp == NULL)
 365     {
 366       lmp = &lmo;
 367
 368       lmo.r_version_offset = 0;
 369       lmo.r_version_size = 4;
 370       lmo.r_map_offset = 8;
 371       lmo.r_ldsomap_offset = -1;
 372
 373       /* Everything we need is in the first 40 bytes.  */
 374       lmo.link_map_size = 48;
 375       lmo.l_addr_offset = 0;
 376       lmo.l_name_offset = 16;
 377       lmo.l_ld_offset = 24;
 378       lmo.l_next_offset = 32;
 379       lmo.l_prev_offset = 40;
 380     }
 381
 382   return lmp;
 383 }
 384 \f
 385
 386 static void
 387 mipsnbsd_init_abi (struct gdbarch_info info,
 388                    struct gdbarch *gdbarch)
 389 {
 390   set_gdbarch_regset_from_core_section
 391     (gdbarch, mipsnbsd_regset_from_core_section);
 392
 393   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 394
 395   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 396   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 397
 398   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 399
 400   /* NetBSD/mips has SVR4-style shared libraries.  */
 401   set_solib_svr4_fetch_link_map_offsets
 402     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 403                mipsnbsd_ilp32_fetch_link_map_offsets :
 404                mipsnbsd_lp64_fetch_link_map_offsets));
 405 }
 406 \f
 407
 408 static enum gdb_osabi
 409 mipsnbsd_core_osabi_sniffer (bfd *abfd)
 410 {
 411   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 412     return GDB_OSABI_NETBSD_ELF;
 413
 414   return GDB_OSABI_UNKNOWN;
 415 }
 416
 417 void
 418 _initialize_mipsnbsd_tdep (void)
 419 {
 420   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 421                           mipsnbsd_init_abi);
 422 }