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 "gdb_assert.h"
  31 #include <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 const struct regset mipsnbsd_gregset =
 107 {
 108   NULL,
 109   mipsnbsd_supply_gregset
 110 };
 111
 112 static const 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 #if 0
 215
 216 /* Under NetBSD/mips, signal handler invocations can be identified by the
 217    designated code sequence that is used to return from a signal handler.
 218    In particular, the return address of a signal handler points to the
 219    following code sequence:
 220
 221         addu    a0, sp, 16
 222         li      v0, 295                 # __sigreturn14
 223         syscall
 224
 225    Each instruction has a unique encoding, so we simply attempt to match
 226    the instruction the PC is pointing to with any of the above instructions.
 227    If there is a hit, we know the offset to the start of the designated
 228    sequence and can then check whether we really are executing in the
 229    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 230    start of the return sequence is returned.  */
 231
 232 #define RETCODE_NWORDS  3
 233 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 234
 235 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 236 {
 237   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 238   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 239   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 240 };
 241
 242 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 243 {
 244   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 245   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 246   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 247 };
 248
 249 #endif
 250
 251 /* Figure out where the longjmp will land.  We expect that we have
 252    just entered longjmp and haven't yet setup the stack frame, so the
 253    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 254    jmp_buf structure from which we extract the PC that we will land
 255    at.  The PC is copied into *pc.  This routine returns true on
 256    success.  */
 257
 258 #define NBSD_MIPS_JB_PC                 (2 * 4)
 259 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 260 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 261                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 262
 263 static int
 264 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 265 {
 266   struct gdbarch *gdbarch = get_frame_arch (frame);
 267   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 268   CORE_ADDR jb_addr;
 269   gdb_byte *buf;
 270
 271   buf = alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 272
 273   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 274
 275   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 276                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 277     return 0;
 278
 279   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 280                                   byte_order);
 281   return 1;
 282 }
 283
 284 static int
 285 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 286 {
 287   return (regno == MIPS_ZERO_REGNUM
 288           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 289 }
 290
 291 static int
 292 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 293 {
 294   return (regno == MIPS_ZERO_REGNUM
 295           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 296 }
 297
 298 /* Shared library support.  */
 299
 300 /* NetBSD/mips uses a slightly different `struct link_map' than the
 301    other NetBSD platforms.  */
 302
 303 static struct link_map_offsets *
 304 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 305 {
 306   static struct link_map_offsets lmo;
 307   static struct link_map_offsets *lmp = NULL;
 308
 309   if (lmp == NULL)
 310     {
 311       lmp = &lmo;
 312
 313       lmo.r_version_offset = 0;
 314       lmo.r_version_size = 4;
 315       lmo.r_map_offset = 4;
 316       lmo.r_brk_offset = 8;
 317       lmo.r_ldsomap_offset = -1;
 318
 319       /* Everything we need is in the first 24 bytes.  */
 320       lmo.link_map_size = 24;
 321       lmo.l_addr_offset = 4;
 322       lmo.l_name_offset = 8;
 323       lmo.l_ld_offset = 12;
 324       lmo.l_next_offset = 16;
 325       lmo.l_prev_offset = 20;
 326     }
 327
 328   return lmp;
 329 }
 330
 331 static struct link_map_offsets *
 332 mipsnbsd_lp64_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 = 8;
 344       lmo.r_brk_offset = 16;
 345       lmo.r_ldsomap_offset = -1;
 346
 347       /* Everything we need is in the first 40 bytes.  */
 348       lmo.link_map_size = 48;
 349       lmo.l_addr_offset = 0;
 350       lmo.l_name_offset = 16;
 351       lmo.l_ld_offset = 24;
 352       lmo.l_next_offset = 32;
 353       lmo.l_prev_offset = 40;
 354     }
 355
 356   return lmp;
 357 }
 358 \f
 359
 360 static void
 361 mipsnbsd_init_abi (struct gdbarch_info info,
 362                    struct gdbarch *gdbarch)
 363 {
 364   set_gdbarch_regset_from_core_section
 365     (gdbarch, mipsnbsd_regset_from_core_section);
 366
 367   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 368
 369   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 370   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 371
 372   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 373
 374   /* NetBSD/mips has SVR4-style shared libraries.  */
 375   set_solib_svr4_fetch_link_map_offsets
 376     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 377                mipsnbsd_ilp32_fetch_link_map_offsets :
 378                mipsnbsd_lp64_fetch_link_map_offsets));
 379 }
 380 \f
 381
 382 /* Provide a prototype to silence -Wmissing-prototypes.  */
 383 extern initialize_file_ftype _initialize_mipsnbsd_tdep;
 384
 385 void
 386 _initialize_mipsnbsd_tdep (void)
 387 {
 388   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD_ELF,
 389                           mipsnbsd_init_abi);
 390 }