gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011
   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,
 177                        const char *fpregs, int regno)
 178 {
 179   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 180   int i;
 181
 182   for (i = gdbarch_fp0_regnum (gdbarch);
 183        i <= mips_regnum (gdbarch)->fp_implementation_revision;
 184        i++)
 185     {
 186       if (regno == i || regno == -1)
 187         {
 188           if (gdbarch_cannot_fetch_register (gdbarch, i))
 189             regcache_raw_supply (regcache, i, NULL);
 190           else
 191             regcache_raw_supply (regcache, i,
 192                                  fpregs
 193                                  + ((i - gdbarch_fp0_regnum (gdbarch))
 194                                     * mips_isa_regsize (gdbarch)));
 195         }
 196     }
 197 }
 198
 199 void
 200 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 201 {
 202   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 203   int i;
 204
 205   for (i = gdbarch_fp0_regnum (gdbarch);
 206        i <= mips_regnum (gdbarch)->fp_control_status;
 207        i++)
 208     if ((regno == i || regno == -1)
 209         && ! gdbarch_cannot_store_register (gdbarch, i))
 210       regcache_raw_collect (regcache, i,
 211                             fpregs + ((i - gdbarch_fp0_regnum (gdbarch))
 212                               * mips_isa_regsize (gdbarch)));
 213 }
 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 /* Figure out where the longjmp will land.  We expect that we have
 249    just entered longjmp and haven't yet setup the stack frame, so the
 250    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 251    jmp_buf structure from which we extract the PC that we will land
 252    at.  The PC is copied into *pc.  This routine returns true on
 253    success.  */
 254
 255 #define NBSD_MIPS_JB_PC                 (2 * 4)
 256 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 257 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 258                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 259
 260 static int
 261 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 262 {
 263   struct gdbarch *gdbarch = get_frame_arch (frame);
 264   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 265   CORE_ADDR jb_addr;
 266   char *buf;
 267
 268   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 269
 270   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 271
 272   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 273                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 274     return 0;
 275
 276   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 277                                   byte_order);
 278   return 1;
 279 }
 280
 281 static int
 282 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 283 {
 284   return (regno == MIPS_ZERO_REGNUM
 285           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 286 }
 287
 288 static int
 289 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 290 {
 291   return (regno == MIPS_ZERO_REGNUM
 292           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 293 }
 294
 295 /* Shared library support.  */
 296
 297 /* NetBSD/mips uses a slightly different `struct link_map' than the
 298    other NetBSD platforms.  */
 299
 300 static struct link_map_offsets *
 301 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 302 {
 303   static struct link_map_offsets lmo;
 304   static struct link_map_offsets *lmp = NULL;
 305
 306   if (lmp == NULL)
 307     {
 308       lmp = &lmo;
 309
 310       lmo.r_version_offset = 0;
 311       lmo.r_version_size = 4;
 312       lmo.r_map_offset = 4;
 313       lmo.r_brk_offset = 8;
 314       lmo.r_ldsomap_offset = -1;
 315
 316       /* Everything we need is in the first 24 bytes.  */
 317       lmo.link_map_size = 24;
 318       lmo.l_addr_offset = 4;
 319       lmo.l_name_offset = 8;
 320       lmo.l_ld_offset = 12;
 321       lmo.l_next_offset = 16;
 322       lmo.l_prev_offset = 20;
 323     }
 324
 325   return lmp;
 326 }
 327
 328 static struct link_map_offsets *
 329 mipsnbsd_lp64_fetch_link_map_offsets (void)
 330 {
 331   static struct link_map_offsets lmo;
 332   static struct link_map_offsets *lmp = NULL;
 333
 334   if (lmp == NULL)
 335     {
 336       lmp = &lmo;
 337
 338       lmo.r_version_offset = 0;
 339       lmo.r_version_size = 4;
 340       lmo.r_map_offset = 8;
 341       lmo.r_brk_offset = 16;
 342       lmo.r_ldsomap_offset = -1;
 343
 344       /* Everything we need is in the first 40 bytes.  */
 345       lmo.link_map_size = 48;
 346       lmo.l_addr_offset = 0;
 347       lmo.l_name_offset = 16;
 348       lmo.l_ld_offset = 24;
 349       lmo.l_next_offset = 32;
 350       lmo.l_prev_offset = 40;
 351     }
 352
 353   return lmp;
 354 }
 355 \f
 356
 357 static void
 358 mipsnbsd_init_abi (struct gdbarch_info info,
 359                    struct gdbarch *gdbarch)
 360 {
 361   set_gdbarch_regset_from_core_section
 362     (gdbarch, mipsnbsd_regset_from_core_section);
 363
 364   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 365
 366   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 367   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 368
 369   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 370
 371   /* NetBSD/mips has SVR4-style shared libraries.  */
 372   set_solib_svr4_fetch_link_map_offsets
 373     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 374                mipsnbsd_ilp32_fetch_link_map_offsets :
 375                mipsnbsd_lp64_fetch_link_map_offsets));
 376 }
 377 \f
 378
 379 /* Provide a prototype to silence -Wmissing-prototypes.  */
 380 extern initialize_file_ftype _initialize_mipsnbsd_tdep;
 381
 382 void
 383 _initialize_mipsnbsd_tdep (void)
 384 {
 385   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 386                           mipsnbsd_init_abi);
 387 }