gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002-2014 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 <string.h>
  31
  32 #include "nbsd-tdep.h"
  33 #include "mipsnbsd-tdep.h"
  34 #include "mips-tdep.h"
  35
  36 #include "solib-svr4.h"
  37
  38 /* Shorthand for some register numbers used below.  */
  39 #define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
  40 #define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
  41 #define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
  42
  43 /* Core file support.  */
  44
  45 /* Number of registers in `struct reg' from <machine/reg.h>.  */
  46 #define MIPSNBSD_NUM_GREGS      38
  47
  48 /* Number of registers in `struct fpreg' from <machine/reg.h>.  */
  49 #define MIPSNBSD_NUM_FPREGS     33
  50
  51 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  52    in the floating-point register set REGSET to register cache
  53    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  54
  55 static void
  56 mipsnbsd_supply_fpregset (const struct regset *regset,
  57                           struct regcache *regcache,
  58                           int regnum, const void *fpregs, size_t len)
  59 {
  60   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  61   const char *regs = fpregs;
  62   int i;
  63
  64   gdb_assert (len >= MIPSNBSD_NUM_FPREGS * regsize);
  65
  66   for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
  67     {
  68       if (regnum == i || regnum == -1)
  69         regcache_raw_supply (regcache, i,
  70                              regs + (i - MIPS_FP0_REGNUM) * regsize);
  71     }
  72 }
  73
  74 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  75    in the general-purpose register set REGSET to register cache
  76    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  77
  78 static void
  79 mipsnbsd_supply_gregset (const struct regset *regset,
  80                          struct regcache *regcache, int regnum,
  81                          const void *gregs, size_t len)
  82 {
  83   size_t regsize = mips_isa_regsize (get_regcache_arch (regcache));
  84   const char *regs = gregs;
  85   int i;
  86
  87   gdb_assert (len >= MIPSNBSD_NUM_GREGS * regsize);
  88
  89   for (i = 0; i <= MIPS_PC_REGNUM; i++)
  90     {
  91       if (regnum == i || regnum == -1)
  92         regcache_raw_supply (regcache, i, regs + i * regsize);
  93     }
  94
  95   if (len >= (MIPSNBSD_NUM_GREGS + MIPSNBSD_NUM_FPREGS) * regsize)
  96     {
  97       regs += MIPSNBSD_NUM_GREGS * regsize;
  98       len -= MIPSNBSD_NUM_GREGS * regsize;
  99       mipsnbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 100     }
 101 }
 102
 103 /* NetBSD/mips register sets.  */
 104
 105 static const struct regset mipsnbsd_gregset =
 106 {
 107   NULL,
 108   mipsnbsd_supply_gregset
 109 };
 110
 111 static const struct regset mipsnbsd_fpregset =
 112 {
 113   NULL,
 114   mipsnbsd_supply_fpregset
 115 };
 116
 117 /* Return the appropriate register set for the core section identified
 118    by SECT_NAME and SECT_SIZE.  */
 119
 120 static const struct regset *
 121 mipsnbsd_regset_from_core_section (struct gdbarch *gdbarch,
 122                                    const char *sect_name, size_t sect_size)
 123 {
 124   size_t regsize = mips_isa_regsize (gdbarch);
 125
 126   if (strcmp (sect_name, ".reg") == 0
 127       && sect_size >= MIPSNBSD_NUM_GREGS * regsize)
 128     return &mipsnbsd_gregset;
 129
 130   if (strcmp (sect_name, ".reg2") == 0
 131       && sect_size >= MIPSNBSD_NUM_FPREGS * regsize)
 132     return &mipsnbsd_fpregset;
 133
 134   return NULL;
 135 }
 136 \f
 137
 138 /* Conveniently, GDB uses the same register numbering as the
 139    ptrace register structure used by NetBSD/mips.  */
 140
 141 void
 142 mipsnbsd_supply_reg (struct regcache *regcache, const char *regs, int regno)
 143 {
 144   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 145   int i;
 146
 147   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 148     {
 149       if (regno == i || regno == -1)
 150         {
 151           if (gdbarch_cannot_fetch_register (gdbarch, i))
 152             regcache_raw_supply (regcache, i, NULL);
 153           else
 154             regcache_raw_supply (regcache, i,
 155                                  regs + (i * mips_isa_regsize (gdbarch)));
 156         }
 157     }
 158 }
 159
 160 void
 161 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 162 {
 163   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 164   int i;
 165
 166   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 167     if ((regno == i || regno == -1)
 168         && ! gdbarch_cannot_store_register (gdbarch, i))
 169       regcache_raw_collect (regcache, i,
 170                             regs + (i * mips_isa_regsize (gdbarch)));
 171 }
 172
 173 void
 174 mipsnbsd_supply_fpreg (struct regcache *regcache,
 175                        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 #if 0
 214
 215 /* Under NetBSD/mips, signal handler invocations can be identified by the
 216    designated code sequence that is used to return from a signal handler.
 217    In particular, the return address of a signal handler points to the
 218    following code sequence:
 219
 220         addu    a0, sp, 16
 221         li      v0, 295                 # __sigreturn14
 222         syscall
 223
 224    Each instruction has a unique encoding, so we simply attempt to match
 225    the instruction the PC is pointing to with any of the above instructions.
 226    If there is a hit, we know the offset to the start of the designated
 227    sequence and can then check whether we really are executing in the
 228    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 229    start of the return sequence is returned.  */
 230
 231 #define RETCODE_NWORDS  3
 232 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 233
 234 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 235 {
 236   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 237   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 238   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 239 };
 240
 241 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 242 {
 243   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 244   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 245   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 246 };
 247
 248 #endif
 249
 250 /* Figure out where the longjmp will land.  We expect that we have
 251    just entered longjmp and haven't yet setup the stack frame, so the
 252    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 253    jmp_buf structure from which we extract the PC that we will land
 254    at.  The PC is copied into *pc.  This routine returns true on
 255    success.  */
 256
 257 #define NBSD_MIPS_JB_PC                 (2 * 4)
 258 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 259 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 260                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 261
 262 static int
 263 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 264 {
 265   struct gdbarch *gdbarch = get_frame_arch (frame);
 266   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 267   CORE_ADDR jb_addr;
 268   gdb_byte *buf;
 269
 270   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 271
 272   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 273
 274   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 275                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 276     return 0;
 277
 278   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 279                                   byte_order);
 280   return 1;
 281 }
 282
 283 static int
 284 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 285 {
 286   return (regno == MIPS_ZERO_REGNUM
 287           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 288 }
 289
 290 static int
 291 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 292 {
 293   return (regno == MIPS_ZERO_REGNUM
 294           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 295 }
 296
 297 /* Shared library support.  */
 298
 299 /* NetBSD/mips uses a slightly different `struct link_map' than the
 300    other NetBSD platforms.  */
 301
 302 static struct link_map_offsets *
 303 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 304 {
 305   static struct link_map_offsets lmo;
 306   static struct link_map_offsets *lmp = NULL;
 307
 308   if (lmp == NULL)
 309     {
 310       lmp = &lmo;
 311
 312       lmo.r_version_offset = 0;
 313       lmo.r_version_size = 4;
 314       lmo.r_map_offset = 4;
 315       lmo.r_brk_offset = 8;
 316       lmo.r_ldsomap_offset = -1;
 317
 318       /* Everything we need is in the first 24 bytes.  */
 319       lmo.link_map_size = 24;
 320       lmo.l_addr_offset = 4;
 321       lmo.l_name_offset = 8;
 322       lmo.l_ld_offset = 12;
 323       lmo.l_next_offset = 16;
 324       lmo.l_prev_offset = 20;
 325     }
 326
 327   return lmp;
 328 }
 329
 330 static struct link_map_offsets *
 331 mipsnbsd_lp64_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 = 8;
 343       lmo.r_brk_offset = 16;
 344       lmo.r_ldsomap_offset = -1;
 345
 346       /* Everything we need is in the first 40 bytes.  */
 347       lmo.link_map_size = 48;
 348       lmo.l_addr_offset = 0;
 349       lmo.l_name_offset = 16;
 350       lmo.l_ld_offset = 24;
 351       lmo.l_next_offset = 32;
 352       lmo.l_prev_offset = 40;
 353     }
 354
 355   return lmp;
 356 }
 357 \f
 358
 359 static void
 360 mipsnbsd_init_abi (struct gdbarch_info info,
 361                    struct gdbarch *gdbarch)
 362 {
 363   set_gdbarch_regset_from_core_section
 364     (gdbarch, mipsnbsd_regset_from_core_section);
 365
 366   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 367
 368   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 369   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 370
 371   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 372
 373   /* NetBSD/mips has SVR4-style shared libraries.  */
 374   set_solib_svr4_fetch_link_map_offsets
 375     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 376                mipsnbsd_ilp32_fetch_link_map_offsets :
 377                mipsnbsd_lp64_fetch_link_map_offsets));
 378 }
 379 \f
 380
 381 /* Provide a prototype to silence -Wmissing-prototypes.  */
 382 extern initialize_file_ftype _initialize_mipsnbsd_tdep;
 383
 384 void
 385 _initialize_mipsnbsd_tdep (void)
 386 {
 387   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 388                           mipsnbsd_init_abi);
 389 }