gdb/mips-nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002-2018 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 "nbsd-tdep.h"
  31 #include "mips-nbsd-tdep.h"
  32 #include "mips-tdep.h"
  33
  34 #include "solib-svr4.h"
  35
  36 /* Shorthand for some register numbers used below.  */
  37 #define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
  38 #define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
  39 #define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
  40
  41 /* Core file support.  */
  42
  43 /* Number of registers in `struct reg' from <machine/reg.h>.  */
  44 #define MIPSNBSD_NUM_GREGS      38
  45
  46 /* Number of registers in `struct fpreg' from <machine/reg.h>.  */
  47 #define MIPSNBSD_NUM_FPREGS     33
  48
  49 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  50    in the floating-point register set REGSET to register cache
  51    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  52
  53 static void
  54 mipsnbsd_supply_fpregset (const struct regset *regset,
  55                           struct regcache *regcache,
  56                           int regnum, const void *fpregs, size_t len)
  57 {
  58   size_t regsize = mips_isa_regsize (regcache->arch ());
  59   const char *regs = (const char *) fpregs;
  60   int i;
  61
  62   gdb_assert (len >= MIPSNBSD_NUM_FPREGS * regsize);
  63
  64   for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
  65     {
  66       if (regnum == i || regnum == -1)
  67         regcache_raw_supply (regcache, i,
  68                              regs + (i - MIPS_FP0_REGNUM) * regsize);
  69     }
  70 }
  71
  72 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  73    in the general-purpose register set REGSET to register cache
  74    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  75
  76 static void
  77 mipsnbsd_supply_gregset (const struct regset *regset,
  78                          struct regcache *regcache, int regnum,
  79                          const void *gregs, size_t len)
  80 {
  81   size_t regsize = mips_isa_regsize (regcache->arch ());
  82   const char *regs = (const char *) gregs;
  83   int i;
  84
  85   gdb_assert (len >= MIPSNBSD_NUM_GREGS * regsize);
  86
  87   for (i = 0; i <= MIPS_PC_REGNUM; i++)
  88     {
  89       if (regnum == i || regnum == -1)
  90         regcache_raw_supply (regcache, i, regs + i * regsize);
  91     }
  92
  93   if (len >= (MIPSNBSD_NUM_GREGS + MIPSNBSD_NUM_FPREGS) * regsize)
  94     {
  95       regs += MIPSNBSD_NUM_GREGS * regsize;
  96       len -= MIPSNBSD_NUM_GREGS * regsize;
  97       mipsnbsd_supply_fpregset (regset, regcache, regnum, regs, len);
  98     }
  99 }
 100
 101 /* NetBSD/mips register sets.  */
 102
 103 static const struct regset mipsnbsd_gregset =
 104 {
 105   NULL,
 106   mipsnbsd_supply_gregset,
 107   NULL,
 108   REGSET_VARIABLE_SIZE
 109 };
 110
 111 static const struct regset mipsnbsd_fpregset =
 112 {
 113   NULL,
 114   mipsnbsd_supply_fpregset
 115 };
 116
 117 /* Iterate over core file register note sections.  */
 118
 119 static void
 120 mipsnbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 121                                        iterate_over_regset_sections_cb *cb,
 122                                        void *cb_data,
 123                                        const struct regcache *regcache)
 124 {
 125   size_t regsize = mips_isa_regsize (gdbarch);
 126
 127   cb (".reg", MIPSNBSD_NUM_GREGS * regsize, &mipsnbsd_gregset,
 128       NULL, cb_data);
 129   cb (".reg2", MIPSNBSD_NUM_FPREGS * regsize, &mipsnbsd_fpregset,
 130       NULL, cb_data);
 131 }
 132 \f
 133
 134 /* Conveniently, GDB uses the same register numbering as the
 135    ptrace register structure used by NetBSD/mips.  */
 136
 137 void
 138 mipsnbsd_supply_reg (struct regcache *regcache, const char *regs, int regno)
 139 {
 140   struct gdbarch *gdbarch = regcache->arch ();
 141   int i;
 142
 143   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 144     {
 145       if (regno == i || regno == -1)
 146         {
 147           if (gdbarch_cannot_fetch_register (gdbarch, i))
 148             regcache_raw_supply (regcache, i, NULL);
 149           else
 150             regcache_raw_supply (regcache, i,
 151                                  regs + (i * mips_isa_regsize (gdbarch)));
 152         }
 153     }
 154 }
 155
 156 void
 157 mipsnbsd_fill_reg (const struct regcache *regcache, char *regs, int regno)
 158 {
 159   struct gdbarch *gdbarch = regcache->arch ();
 160   int i;
 161
 162   for (i = 0; i <= gdbarch_pc_regnum (gdbarch); i++)
 163     if ((regno == i || regno == -1)
 164         && ! gdbarch_cannot_store_register (gdbarch, i))
 165       regcache_raw_collect (regcache, i,
 166                             regs + (i * mips_isa_regsize (gdbarch)));
 167 }
 168
 169 void
 170 mipsnbsd_supply_fpreg (struct regcache *regcache,
 171                        const char *fpregs, int regno)
 172 {
 173   struct gdbarch *gdbarch = regcache->arch ();
 174   int i;
 175
 176   for (i = gdbarch_fp0_regnum (gdbarch);
 177        i <= mips_regnum (gdbarch)->fp_implementation_revision;
 178        i++)
 179     {
 180       if (regno == i || regno == -1)
 181         {
 182           if (gdbarch_cannot_fetch_register (gdbarch, i))
 183             regcache_raw_supply (regcache, i, NULL);
 184           else
 185             regcache_raw_supply (regcache, i,
 186                                  fpregs
 187                                  + ((i - gdbarch_fp0_regnum (gdbarch))
 188                                     * mips_isa_regsize (gdbarch)));
 189         }
 190     }
 191 }
 192
 193 void
 194 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 195 {
 196   struct gdbarch *gdbarch = regcache->arch ();
 197   int i;
 198
 199   for (i = gdbarch_fp0_regnum (gdbarch);
 200        i <= mips_regnum (gdbarch)->fp_control_status;
 201        i++)
 202     if ((regno == i || regno == -1)
 203         && ! gdbarch_cannot_store_register (gdbarch, i))
 204       regcache_raw_collect (regcache, i,
 205                             fpregs + ((i - gdbarch_fp0_regnum (gdbarch))
 206                               * mips_isa_regsize (gdbarch)));
 207 }
 208
 209 #if 0
 210
 211 /* Under NetBSD/mips, signal handler invocations can be identified by the
 212    designated code sequence that is used to return from a signal handler.
 213    In particular, the return address of a signal handler points to the
 214    following code sequence:
 215
 216         addu    a0, sp, 16
 217         li      v0, 295                 # __sigreturn14
 218         syscall
 219
 220    Each instruction has a unique encoding, so we simply attempt to match
 221    the instruction the PC is pointing to with any of the above instructions.
 222    If there is a hit, we know the offset to the start of the designated
 223    sequence and can then check whether we really are executing in the
 224    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 225    start of the return sequence is returned.  */
 226
 227 #define RETCODE_NWORDS  3
 228 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 229
 230 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 231 {
 232   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 233   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 234   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 235 };
 236
 237 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 238 {
 239   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 240   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 241   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 242 };
 243
 244 #endif
 245
 246 /* Figure out where the longjmp will land.  We expect that we have
 247    just entered longjmp and haven't yet setup the stack frame, so the
 248    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 249    jmp_buf structure from which we extract the PC that we will land
 250    at.  The PC is copied into *pc.  This routine returns true on
 251    success.  */
 252
 253 #define NBSD_MIPS_JB_PC                 (2 * 4)
 254 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 255 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 256                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 257
 258 static int
 259 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 260 {
 261   struct gdbarch *gdbarch = get_frame_arch (frame);
 262   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 263   CORE_ADDR jb_addr;
 264   gdb_byte *buf;
 265
 266   buf = (gdb_byte *) alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 267
 268   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 269
 270   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 271                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 272     return 0;
 273
 274   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 275                                   byte_order);
 276   return 1;
 277 }
 278
 279 static int
 280 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 281 {
 282   return (regno == MIPS_ZERO_REGNUM
 283           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 284 }
 285
 286 static int
 287 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 288 {
 289   return (regno == MIPS_ZERO_REGNUM
 290           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 291 }
 292
 293 /* Shared library support.  */
 294
 295 /* NetBSD/mips uses a slightly different `struct link_map' than the
 296    other NetBSD platforms.  */
 297
 298 static struct link_map_offsets *
 299 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 300 {
 301   static struct link_map_offsets lmo;
 302   static struct link_map_offsets *lmp = NULL;
 303
 304   if (lmp == NULL)
 305     {
 306       lmp = &lmo;
 307
 308       lmo.r_version_offset = 0;
 309       lmo.r_version_size = 4;
 310       lmo.r_map_offset = 4;
 311       lmo.r_brk_offset = 8;
 312       lmo.r_ldsomap_offset = -1;
 313
 314       /* Everything we need is in the first 24 bytes.  */
 315       lmo.link_map_size = 24;
 316       lmo.l_addr_offset = 4;
 317       lmo.l_name_offset = 8;
 318       lmo.l_ld_offset = 12;
 319       lmo.l_next_offset = 16;
 320       lmo.l_prev_offset = 20;
 321     }
 322
 323   return lmp;
 324 }
 325
 326 static struct link_map_offsets *
 327 mipsnbsd_lp64_fetch_link_map_offsets (void)
 328 {
 329   static struct link_map_offsets lmo;
 330   static struct link_map_offsets *lmp = NULL;
 331
 332   if (lmp == NULL)
 333     {
 334       lmp = &lmo;
 335
 336       lmo.r_version_offset = 0;
 337       lmo.r_version_size = 4;
 338       lmo.r_map_offset = 8;
 339       lmo.r_brk_offset = 16;
 340       lmo.r_ldsomap_offset = -1;
 341
 342       /* Everything we need is in the first 40 bytes.  */
 343       lmo.link_map_size = 48;
 344       lmo.l_addr_offset = 0;
 345       lmo.l_name_offset = 16;
 346       lmo.l_ld_offset = 24;
 347       lmo.l_next_offset = 32;
 348       lmo.l_prev_offset = 40;
 349     }
 350
 351   return lmp;
 352 }
 353 \f
 354
 355 static void
 356 mipsnbsd_init_abi (struct gdbarch_info info,
 357                    struct gdbarch *gdbarch)
 358 {
 359   set_gdbarch_iterate_over_regset_sections
 360     (gdbarch, mipsnbsd_iterate_over_regset_sections);
 361
 362   set_gdbarch_get_longjmp_target (gdbarch, mipsnbsd_get_longjmp_target);
 363
 364   set_gdbarch_cannot_fetch_register (gdbarch, mipsnbsd_cannot_fetch_register);
 365   set_gdbarch_cannot_store_register (gdbarch, mipsnbsd_cannot_store_register);
 366
 367   set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
 368
 369   /* NetBSD/mips has SVR4-style shared libraries.  */
 370   set_solib_svr4_fetch_link_map_offsets
 371     (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
 372                mipsnbsd_ilp32_fetch_link_map_offsets :
 373                mipsnbsd_lp64_fetch_link_map_offsets));
 374 }
 375
 376 void
 377 _initialize_mipsnbsd_tdep (void)
 378 {
 379   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD,
 380                           mipsnbsd_init_abi);
 381 }