gdb/mipsnbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002-2013 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,
 176                        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 /* Figure out where the longjmp will land.  We expect that we have
 248    just entered longjmp and haven't yet setup the stack frame, so the
 249    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 250    jmp_buf structure from which we extract the PC that we will land
 251    at.  The PC is copied into *pc.  This routine returns true on
 252    success.  */
 253
 254 #define NBSD_MIPS_JB_PC                 (2 * 4)
 255 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 256 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 257                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 258
 259 static int
 260 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 261 {
 262   struct gdbarch *gdbarch = get_frame_arch (frame);
 263   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 264   CORE_ADDR jb_addr;
 265   gdb_byte *buf;
 266
 267   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 268
 269   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 270
 271   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 272                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 273     return 0;
 274
 275   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 276                                   byte_order);
 277   return 1;
 278 }
 279
 280 static int
 281 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 282 {
 283   return (regno == MIPS_ZERO_REGNUM
 284           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 285 }
 286
 287 static int
 288 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 289 {
 290   return (regno == MIPS_ZERO_REGNUM
 291           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 292 }
 293
 294 /* Shared library support.  */
 295
 296 /* NetBSD/mips uses a slightly different `struct link_map' than the
 297    other NetBSD platforms.  */
 298
 299 static struct link_map_offsets *
 300 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 301 {
 302   static struct link_map_offsets lmo;
 303   static struct link_map_offsets *lmp = NULL;
 304
 305   if (lmp == NULL)
 306     {
 307       lmp = &lmo;
 308
 309       lmo.r_version_offset = 0;
 310       lmo.r_version_size = 4;
 311       lmo.r_map_offset = 4;
 312       lmo.r_brk_offset = 8;
 313       lmo.r_ldsomap_offset = -1;
 314
 315       /* Everything we need is in the first 24 bytes.  */
 316       lmo.link_map_size = 24;
 317       lmo.l_addr_offset = 4;
 318       lmo.l_name_offset = 8;
 319       lmo.l_ld_offset = 12;
 320       lmo.l_next_offset = 16;
 321       lmo.l_prev_offset = 20;
 322     }
 323
 324   return lmp;
 325 }
 326
 327 static struct link_map_offsets *
 328 mipsnbsd_lp64_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 = 8;
 340       lmo.r_brk_offset = 16;
 341       lmo.r_ldsomap_offset = -1;
 342
 343       /* Everything we need is in the first 40 bytes.  */
 344       lmo.link_map_size = 48;
 345       lmo.l_addr_offset = 0;
 346       lmo.l_name_offset = 16;
 347       lmo.l_ld_offset = 24;
 348       lmo.l_next_offset = 32;
 349       lmo.l_prev_offset = 40;
 350     }
 351
 352   return lmp;
 353 }
 354 \f
 355
 356 static void
 357 mipsnbsd_init_abi (struct gdbarch_info info,
 358                    struct gdbarch *gdbarch)
 359 {
 360   set_gdbarch_regset_from_core_section
 361     (gdbarch, mipsnbsd_regset_from_core_section);
 362
 363   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 364
 365   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 366   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 367
 368   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 369
 370   /* NetBSD/mips has SVR4-style shared libraries.  */
 371   set_solib_svr4_fetch_link_map_offsets
 372     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 373                mipsnbsd_ilp32_fetch_link_map_offsets :
 374                mipsnbsd_lp64_fetch_link_map_offsets));
 375 }
 376 \f
 377
 378 /* Provide a prototype to silence -Wmissing-prototypes.  */
 379 extern initialize_file_ftype _initialize_mipsnbsd_tdep;
 380
 381 void
 382 _initialize_mipsnbsd_tdep (void)
 383 {
 384   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 385                           mipsnbsd_init_abi);
 386 }