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