gdb/alphanbsd-tdep.c

   1 /* Target-dependent code for NetBSD/alpha.
   2
   3    Copyright (C) 2002-2015 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 "frame.h"
  24 #include "gdbcore.h"
  25 #include "osabi.h"
  26 #include "regcache.h"
  27 #include "regset.h"
  28 #include "value.h"
  29
  30 #include "alpha-tdep.h"
  31 #include "alphabsd-tdep.h"
  32 #include "nbsd-tdep.h"
  33 #include "solib-svr4.h"
  34 #include "target.h"
  35
  36 /* Core file support.  */
  37
  38 /* Even though NetBSD/alpha used ELF since day one, it used the
  39    traditional a.out-style core dump format before NetBSD 1.6.  */
  40
  41 /* Sizeof `struct reg' in <machine/reg.h>.  */
  42 #define ALPHANBSD_SIZEOF_GREGS  (32 * 8)
  43
  44 /* Sizeof `struct fpreg' in <machine/reg.h.  */
  45 #define ALPHANBSD_SIZEOF_FPREGS ((32 * 8) + 8)
  46
  47 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  48    in the floating-point register set REGSET to register cache
  49    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  50
  51 static void
  52 alphanbsd_supply_fpregset (const struct regset *regset,
  53                            struct regcache *regcache,
  54                            int regnum, const void *fpregs, size_t len)
  55 {
  56   const gdb_byte *regs = fpregs;
  57   int i;
  58
  59   gdb_assert (len >= ALPHANBSD_SIZEOF_FPREGS);
  60
  61   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
  62     {
  63       if (regnum == i || regnum == -1)
  64         regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);
  65     }
  66
  67   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
  68     regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 32 * 8);
  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 alphanbsd_aout_supply_gregset (const struct regset *regset,
  77                                struct regcache *regcache,
  78                                int regnum, const void *gregs, size_t len)
  79 {
  80   const gdb_byte *regs = gregs;
  81   int i;
  82
  83   /* Table to map a GDB register number to a trapframe register index.  */
  84   static const int regmap[] =
  85   {
  86      0,   1,   2,   3,
  87      4,   5,   6,   7,
  88      8,   9,  10,  11,
  89     12,  13,  14,  15,
  90     30,  31,  32,  16,
  91     17,  18,  19,  20,
  92     21,  22,  23,  24,
  93     25,  29,  26
  94   };
  95
  96   gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);
  97
  98   for (i = 0; i < ARRAY_SIZE(regmap); i++)
  99     {
 100       if (regnum == i || regnum == -1)
 101         regcache_raw_supply (regcache, i, regs + regmap[i] * 8);
 102     }
 103
 104   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 105     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 106
 107   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 108     {
 109       regs += ALPHANBSD_SIZEOF_GREGS;
 110       len -= ALPHANBSD_SIZEOF_GREGS;
 111       alphanbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 112     }
 113 }
 114
 115 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 116    in the general-purpose register set REGSET to register cache
 117    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 118
 119 static void
 120 alphanbsd_supply_gregset (const struct regset *regset,
 121                           struct regcache *regcache,
 122                           int regnum, const void *gregs, size_t len)
 123 {
 124   const gdb_byte *regs = gregs;
 125   int i;
 126
 127   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 128     {
 129       alphanbsd_aout_supply_gregset (regset, regcache, regnum, gregs, len);
 130       return;
 131     }
 132
 133   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 134     {
 135       if (regnum == i || regnum == -1)
 136         regcache_raw_supply (regcache, i, regs + i * 8);
 137     }
 138
 139   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 140     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 141 }
 142
 143 /* NetBSD/alpha register sets.  */
 144
 145 static const struct regset alphanbsd_gregset =
 146 {
 147   NULL,
 148   alphanbsd_supply_gregset
 149 };
 150
 151 static const struct regset alphanbsd_fpregset =
 152 {
 153   NULL,
 154   alphanbsd_supply_fpregset
 155 };
 156
 157 /* Iterate over supported core file register note sections. */
 158
 159 void
 160 alphanbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 161                                         iterate_over_regset_sections_cb *cb,
 162                                         void *cb_data,
 163                                         const struct regcache *regcache)
 164 {
 165   cb (".reg", ALPHANBSD_SIZEOF_GREGS, &alphanbsd_gregset, NULL, cb_data);
 166   cb (".reg2", ALPHANBSD_SIZEOF_FPREGS, &alphanbsd_fpregset, NULL, cb_data);
 167 }
 168 \f
 169
 170 /* Signal trampolines.  */
 171
 172 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 173    designated code sequence that is used to return from a signal handler.
 174    In particular, the return address of a signal handler points to the
 175    following code sequence:
 176
 177         ldq     a0, 0(sp)
 178         lda     sp, 16(sp)
 179         lda     v0, 295(zero)   # __sigreturn14
 180         call_pal callsys
 181
 182    Each instruction has a unique encoding, so we simply attempt to match
 183    the instruction the PC is pointing to with any of the above instructions.
 184    If there is a hit, we know the offset to the start of the designated
 185    sequence and can then check whether we really are executing in the
 186    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 187    start of the return sequence is returned.  */
 188 static const gdb_byte sigtramp_retcode[] =
 189 {
 190   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 191   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 192   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 193   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 194 };
 195 #define RETCODE_NWORDS          4
 196 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 197
 198 static LONGEST
 199 alphanbsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
 200 {
 201   gdb_byte ret[RETCODE_SIZE], w[4];
 202   LONGEST off;
 203   int i;
 204
 205   if (target_read_memory (pc, w, 4) != 0)
 206     return -1;
 207
 208   for (i = 0; i < RETCODE_NWORDS; i++)
 209     {
 210       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 211         break;
 212     }
 213   if (i == RETCODE_NWORDS)
 214     return (-1);
 215
 216   off = i * 4;
 217   pc -= off;
 218
 219   if (target_read_memory (pc, ret, sizeof (ret)) != 0)
 220     return -1;
 221
 222   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 223     return off;
 224
 225   return -1;
 226 }
 227
 228 static int
 229 alphanbsd_pc_in_sigtramp (struct gdbarch *gdbarch,
 230                           CORE_ADDR pc, const char *func_name)
 231 {
 232   return (nbsd_pc_in_sigtramp (pc, func_name)
 233           || alphanbsd_sigtramp_offset (gdbarch, pc) >= 0);
 234 }
 235
 236 static CORE_ADDR
 237 alphanbsd_sigcontext_addr (struct frame_info *frame)
 238 {
 239   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 240      We will probably need to disassemble the trampoline to figure
 241      out which trampoline frame type we have.  */
 242   if (!get_next_frame (frame))
 243     return 0;
 244   return get_frame_base (get_next_frame (frame));
 245 }
 246 \f
 247
 248 static void
 249 alphanbsd_init_abi (struct gdbarch_info info,
 250                     struct gdbarch *gdbarch)
 251 {
 252   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 253
 254   /* Hook into the DWARF CFI frame unwinder.  */
 255   alpha_dwarf2_init_abi (info, gdbarch);
 256
 257   /* Hook into the MDEBUG frame unwinder.  */
 258   alpha_mdebug_init_abi (info, gdbarch);
 259
 260   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 261      must use software single-stepping.  */
 262   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 263
 264   /* NetBSD/alpha has SVR4-style shared libraries.  */
 265   set_solib_svr4_fetch_link_map_offsets
 266     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 267
 268   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 269   tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;
 270   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 271
 272   tdep->jb_pc = 2;
 273   tdep->jb_elt_size = 8;
 274
 275   set_gdbarch_iterate_over_regset_sections
 276     (gdbarch, alphanbsd_iterate_over_regset_sections);
 277 }
 278 \f
 279
 280 static enum gdb_osabi
 281 alphanbsd_core_osabi_sniffer (bfd *abfd)
 282 {
 283   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 284     return GDB_OSABI_NETBSD_ELF;
 285
 286   return GDB_OSABI_UNKNOWN;
 287 }
 288 \f
 289
 290 /* Provide a prototype to silence -Wmissing-prototypes.  */
 291 void _initialize_alphanbsd_tdep (void);
 292
 293 void
 294 _initialize_alphanbsd_tdep (void)
 295 {
 296   /* BFD doesn't set a flavour for NetBSD style a.out core files.  */
 297   gdbarch_register_osabi_sniffer (bfd_arch_alpha, bfd_target_unknown_flavour,
 298                                   alphanbsd_core_osabi_sniffer);
 299
 300   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
 301                           alphanbsd_init_abi);
 302 }