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   NULL,
 150   REGSET_VARIABLE_SIZE
 151 };
 152
 153 static const struct regset alphanbsd_fpregset =
 154 {
 155   NULL,
 156   alphanbsd_supply_fpregset
 157 };
 158
 159 /* Iterate over supported core file register note sections. */
 160
 161 void
 162 alphanbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 163                                         iterate_over_regset_sections_cb *cb,
 164                                         void *cb_data,
 165                                         const struct regcache *regcache)
 166 {
 167   cb (".reg", ALPHANBSD_SIZEOF_GREGS, &alphanbsd_gregset, NULL, cb_data);
 168   cb (".reg2", ALPHANBSD_SIZEOF_FPREGS, &alphanbsd_fpregset, NULL, cb_data);
 169 }
 170 \f
 171
 172 /* Signal trampolines.  */
 173
 174 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 175    designated code sequence that is used to return from a signal handler.
 176    In particular, the return address of a signal handler points to the
 177    following code sequence:
 178
 179         ldq     a0, 0(sp)
 180         lda     sp, 16(sp)
 181         lda     v0, 295(zero)   # __sigreturn14
 182         call_pal callsys
 183
 184    Each instruction has a unique encoding, so we simply attempt to match
 185    the instruction the PC is pointing to with any of the above instructions.
 186    If there is a hit, we know the offset to the start of the designated
 187    sequence and can then check whether we really are executing in the
 188    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 189    start of the return sequence is returned.  */
 190 static const gdb_byte sigtramp_retcode[] =
 191 {
 192   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 193   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 194   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 195   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 196 };
 197 #define RETCODE_NWORDS          4
 198 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 199
 200 static LONGEST
 201 alphanbsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
 202 {
 203   gdb_byte ret[RETCODE_SIZE], w[4];
 204   LONGEST off;
 205   int i;
 206
 207   if (target_read_memory (pc, w, 4) != 0)
 208     return -1;
 209
 210   for (i = 0; i < RETCODE_NWORDS; i++)
 211     {
 212       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 213         break;
 214     }
 215   if (i == RETCODE_NWORDS)
 216     return (-1);
 217
 218   off = i * 4;
 219   pc -= off;
 220
 221   if (target_read_memory (pc, ret, sizeof (ret)) != 0)
 222     return -1;
 223
 224   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 225     return off;
 226
 227   return -1;
 228 }
 229
 230 static int
 231 alphanbsd_pc_in_sigtramp (struct gdbarch *gdbarch,
 232                           CORE_ADDR pc, const char *func_name)
 233 {
 234   return (nbsd_pc_in_sigtramp (pc, func_name)
 235           || alphanbsd_sigtramp_offset (gdbarch, pc) >= 0);
 236 }
 237
 238 static CORE_ADDR
 239 alphanbsd_sigcontext_addr (struct frame_info *frame)
 240 {
 241   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 242      We will probably need to disassemble the trampoline to figure
 243      out which trampoline frame type we have.  */
 244   if (!get_next_frame (frame))
 245     return 0;
 246   return get_frame_base (get_next_frame (frame));
 247 }
 248 \f
 249
 250 static void
 251 alphanbsd_init_abi (struct gdbarch_info info,
 252                     struct gdbarch *gdbarch)
 253 {
 254   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 255
 256   /* Hook into the DWARF CFI frame unwinder.  */
 257   alpha_dwarf2_init_abi (info, gdbarch);
 258
 259   /* Hook into the MDEBUG frame unwinder.  */
 260   alpha_mdebug_init_abi (info, gdbarch);
 261
 262   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 263      must use software single-stepping.  */
 264   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 265
 266   /* NetBSD/alpha has SVR4-style shared libraries.  */
 267   set_solib_svr4_fetch_link_map_offsets
 268     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 269
 270   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 271   tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;
 272   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 273
 274   tdep->jb_pc = 2;
 275   tdep->jb_elt_size = 8;
 276
 277   set_gdbarch_iterate_over_regset_sections
 278     (gdbarch, alphanbsd_iterate_over_regset_sections);
 279 }
 280 \f
 281
 282 static enum gdb_osabi
 283 alphanbsd_core_osabi_sniffer (bfd *abfd)
 284 {
 285   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 286     return GDB_OSABI_NETBSD_ELF;
 287
 288   return GDB_OSABI_UNKNOWN;
 289 }
 290 \f
 291
 292 /* Provide a prototype to silence -Wmissing-prototypes.  */
 293 void _initialize_alphanbsd_tdep (void);
 294
 295 void
 296 _initialize_alphanbsd_tdep (void)
 297 {
 298   /* BFD doesn't set a flavour for NetBSD style a.out core files.  */
 299   gdbarch_register_osabi_sniffer (bfd_arch_alpha, bfd_target_unknown_flavour,
 300                                   alphanbsd_core_osabi_sniffer);
 301
 302   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
 303                           alphanbsd_init_abi);
 304 }