gdb/mips-nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/mips.
   2
   3    Copyright (C) 2002-2020 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_NUM_GREGS * regsize,
 127       &mipsnbsd_gregset, NULL, cb_data);
 128   cb (".reg2", MIPSNBSD_NUM_FPREGS * regsize, MIPSNBSD_NUM_FPREGS * regsize,
 129       &mipsnbsd_fpregset, 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 (i, regs + (i * mips_isa_regsize (gdbarch)));
 165 }
 166
 167 void
 168 mipsnbsd_supply_fpreg (struct regcache *regcache,
 169                        const char *fpregs, int regno)
 170 {
 171   struct gdbarch *gdbarch = regcache->arch ();
 172   int i;
 173
 174   for (i = gdbarch_fp0_regnum (gdbarch);
 175        i <= mips_regnum (gdbarch)->fp_implementation_revision;
 176        i++)
 177     {
 178       if (regno == i || regno == -1)
 179         {
 180           if (gdbarch_cannot_fetch_register (gdbarch, i))
 181             regcache->raw_supply (i, NULL);
 182           else
 183             regcache->raw_supply (i,
 184                                  fpregs
 185                                  + ((i - gdbarch_fp0_regnum (gdbarch))
 186                                     * mips_isa_regsize (gdbarch)));
 187         }
 188     }
 189 }
 190
 191 void
 192 mipsnbsd_fill_fpreg (const struct regcache *regcache, char *fpregs, int regno)
 193 {
 194   struct gdbarch *gdbarch = regcache->arch ();
 195   int i;
 196
 197   for (i = gdbarch_fp0_regnum (gdbarch);
 198        i <= mips_regnum (gdbarch)->fp_control_status;
 199        i++)
 200     if ((regno == i || regno == -1)
 201         && ! gdbarch_cannot_store_register (gdbarch, i))
 202       regcache->raw_collect
 203         (i, (fpregs + ((i - gdbarch_fp0_regnum (gdbarch))
 204              * mips_isa_regsize (gdbarch))));
 205 }
 206
 207 #if 0
 208
 209 /* Under NetBSD/mips, signal handler invocations can be identified by the
 210    designated code sequence that is used to return from a signal handler.
 211    In particular, the return address of a signal handler points to the
 212    following code sequence:
 213
 214         addu    a0, sp, 16
 215         li      v0, 295                 # __sigreturn14
 216         syscall
 217
 218    Each instruction has a unique encoding, so we simply attempt to match
 219    the instruction the PC is pointing to with any of the above instructions.
 220    If there is a hit, we know the offset to the start of the designated
 221    sequence and can then check whether we really are executing in the
 222    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 223    start of the return sequence is returned.  */
 224
 225 #define RETCODE_NWORDS  3
 226 #define RETCODE_SIZE    (RETCODE_NWORDS * 4)
 227
 228 static const unsigned char sigtramp_retcode_mipsel[RETCODE_SIZE] =
 229 {
 230   0x10, 0x00, 0xa4, 0x27,       /* addu a0, sp, 16 */
 231   0x27, 0x01, 0x02, 0x24,       /* li v0, 295 */
 232   0x0c, 0x00, 0x00, 0x00,       /* syscall */
 233 };
 234
 235 static const unsigned char sigtramp_retcode_mipseb[RETCODE_SIZE] =
 236 {
 237   0x27, 0xa4, 0x00, 0x10,       /* addu a0, sp, 16 */
 238   0x24, 0x02, 0x01, 0x27,       /* li v0, 295 */
 239   0x00, 0x00, 0x00, 0x0c,       /* syscall */
 240 };
 241
 242 #endif
 243
 244 /* Figure out where the longjmp will land.  We expect that we have
 245    just entered longjmp and haven't yet setup the stack frame, so the
 246    args are still in the argument regs.  MIPS_A0_REGNUM points at the
 247    jmp_buf structure from which we extract the PC that we will land
 248    at.  The PC is copied into *pc.  This routine returns true on
 249    success.  */
 250
 251 #define NBSD_MIPS_JB_PC                 (2 * 4)
 252 #define NBSD_MIPS_JB_ELEMENT_SIZE(gdbarch)      mips_isa_regsize (gdbarch)
 253 #define NBSD_MIPS_JB_OFFSET(gdbarch)            (NBSD_MIPS_JB_PC * \
 254                                          NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch))
 255
 256 static int
 257 mipsnbsd_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
 258 {
 259   struct gdbarch *gdbarch = get_frame_arch (frame);
 260   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 261   CORE_ADDR jb_addr;
 262   gdb_byte *buf;
 263
 264   buf = (gdb_byte *) alloca (NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch));
 265
 266   jb_addr = get_frame_register_unsigned (frame, MIPS_A0_REGNUM);
 267
 268   if (target_read_memory (jb_addr + NBSD_MIPS_JB_OFFSET (gdbarch), buf,
 269                           NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch)))
 270     return 0;
 271
 272   *pc = extract_unsigned_integer (buf, NBSD_MIPS_JB_ELEMENT_SIZE (gdbarch),
 273                                   byte_order);
 274   return 1;
 275 }
 276
 277 static int
 278 mipsnbsd_cannot_fetch_register (struct gdbarch *gdbarch, int regno)
 279 {
 280   return (regno == MIPS_ZERO_REGNUM
 281           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 282 }
 283
 284 static int
 285 mipsnbsd_cannot_store_register (struct gdbarch *gdbarch, int regno)
 286 {
 287   return (regno == MIPS_ZERO_REGNUM
 288           || regno == mips_regnum (gdbarch)->fp_implementation_revision);
 289 }
 290
 291 /* Shared library support.  */
 292
 293 /* NetBSD/mips uses a slightly different `struct link_map' than the
 294    other NetBSD platforms.  */
 295
 296 static struct link_map_offsets *
 297 mipsnbsd_ilp32_fetch_link_map_offsets (void)
 298 {
 299   static struct link_map_offsets lmo;
 300   static struct link_map_offsets *lmp = NULL;
 301
 302   if (lmp == NULL)
 303     {
 304       lmp = &lmo;
 305
 306       lmo.r_version_offset = 0;
 307       lmo.r_version_size = 4;
 308       lmo.r_map_offset = 4;
 309       lmo.r_brk_offset = 8;
 310       lmo.r_ldsomap_offset = -1;
 311
 312       /* Everything we need is in the first 24 bytes.  */
 313       lmo.link_map_size = 24;
 314       lmo.l_addr_offset = 4;
 315       lmo.l_name_offset = 8;
 316       lmo.l_ld_offset = 12;
 317       lmo.l_next_offset = 16;
 318       lmo.l_prev_offset = 20;
 319     }
 320
 321   return lmp;
 322 }
 323
 324 static struct link_map_offsets *
 325 mipsnbsd_lp64_fetch_link_map_offsets (void)
 326 {
 327   static struct link_map_offsets lmo;
 328   static struct link_map_offsets *lmp = NULL;
 329
 330   if (lmp == NULL)
 331     {
 332       lmp = &lmo;
 333
 334       lmo.r_version_offset = 0;
 335       lmo.r_version_size = 4;
 336       lmo.r_map_offset = 8;
 337       lmo.r_brk_offset = 16;
 338       lmo.r_ldsomap_offset = -1;
 339
 340       /* Everything we need is in the first 40 bytes.  */
 341       lmo.link_map_size = 48;
 342       lmo.l_addr_offset = 0;
 343       lmo.l_name_offset = 16;
 344       lmo.l_ld_offset = 24;
 345       lmo.l_next_offset = 32;
 346       lmo.l_prev_offset = 40;
 347     }
 348
 349   return lmp;
 350 }
 351 \f
 352
 353 static void
 354 mipsnbsd_init_abi (struct gdbarch_info info,
 355                    struct gdbarch *gdbarch)
 356 {
 357   nbsd_init_abi (info, 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 _initialize_mipsnbsd_tdep ();
 377 void
 378 _initialize_mipsnbsd_tdep ()
 379 {
 380   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_NETBSD,
 381                           mipsnbsd_init_abi);
 382 }