gdb/alphanbsd-tdep.c

   1 /* Target-dependent code for NetBSD/alpha.
   2
   3    Copyright (C) 2002-2014 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 "gdb_assert.h"
  31 #include <string.h>
  32
  33 #include "alpha-tdep.h"
  34 #include "alphabsd-tdep.h"
  35 #include "nbsd-tdep.h"
  36 #include "solib-svr4.h"
  37 #include "target.h"
  38
  39 /* Core file support.  */
  40
  41 /* Even though NetBSD/alpha used ELF since day one, it used the
  42    traditional a.out-style core dump format before NetBSD 1.6.  */
  43
  44 /* Sizeof `struct reg' in <machine/reg.h>.  */
  45 #define ALPHANBSD_SIZEOF_GREGS  (32 * 8)
  46
  47 /* Sizeof `struct fpreg' in <machine/reg.h.  */
  48 #define ALPHANBSD_SIZEOF_FPREGS ((32 * 8) + 8)
  49
  50 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  51    in the floating-point register set REGSET to register cache
  52    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  53
  54 static void
  55 alphanbsd_supply_fpregset (const struct regset *regset,
  56                            struct regcache *regcache,
  57                            int regnum, const void *fpregs, size_t len)
  58 {
  59   const gdb_byte *regs = fpregs;
  60   int i;
  61
  62   gdb_assert (len >= ALPHANBSD_SIZEOF_FPREGS);
  63
  64   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
  65     {
  66       if (regnum == i || regnum == -1)
  67         regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);
  68     }
  69
  70   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
  71     regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 32 * 8);
  72 }
  73
  74 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  75    in the general-purpose register set REGSET to register cache
  76    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  77
  78 static void
  79 alphanbsd_supply_gregset (const struct regset *regset,
  80                           struct regcache *regcache,
  81                           int regnum, const void *gregs, size_t len)
  82 {
  83   const gdb_byte *regs = gregs;
  84   int i;
  85
  86   gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);
  87
  88   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
  89     {
  90       if (regnum == i || regnum == -1)
  91         regcache_raw_supply (regcache, i, regs + i * 8);
  92     }
  93
  94   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
  95     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
  96 }
  97
  98 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  99    in the general-purpose register set REGSET to register cache
 100    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 101
 102 static void
 103 alphanbsd_aout_supply_gregset (const struct regset *regset,
 104                                struct regcache *regcache,
 105                                int regnum, const void *gregs, size_t len)
 106 {
 107   const gdb_byte *regs = gregs;
 108   int i;
 109
 110   /* Table to map a GDB register number to a trapframe register index.  */
 111   static const int regmap[] =
 112   {
 113      0,   1,   2,   3,
 114      4,   5,   6,   7,
 115      8,   9,  10,  11,
 116     12,  13,  14,  15,
 117     30,  31,  32,  16,
 118     17,  18,  19,  20,
 119     21,  22,  23,  24,
 120     25,  29,  26
 121   };
 122
 123   gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);
 124
 125   for (i = 0; i < ARRAY_SIZE(regmap); i++)
 126     {
 127       if (regnum == i || regnum == -1)
 128         regcache_raw_supply (regcache, i, regs + regmap[i] * 8);
 129     }
 130
 131   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 132     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 133
 134   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 135     {
 136       regs += ALPHANBSD_SIZEOF_GREGS;
 137       len -= ALPHANBSD_SIZEOF_GREGS;
 138       alphanbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 139     }
 140 }
 141
 142 /* NetBSD/alpha register sets.  */
 143
 144 static const struct regset alphanbsd_gregset =
 145 {
 146   NULL,
 147   alphanbsd_supply_gregset
 148 };
 149
 150 static const struct regset alphanbsd_fpregset =
 151 {
 152   NULL,
 153   alphanbsd_supply_fpregset
 154 };
 155
 156 static const struct regset alphanbsd_aout_gregset =
 157 {
 158   NULL,
 159   alphanbsd_aout_supply_gregset
 160 };
 161
 162 /* Return the appropriate register set for the core section identified
 163    by SECT_NAME and SECT_SIZE.  */
 164
 165 const struct regset *
 166 alphanbsd_regset_from_core_section (struct gdbarch *gdbarch,
 167                                     const char *sect_name, size_t sect_size)
 168 {
 169   if (strcmp (sect_name, ".reg") == 0 && sect_size >= ALPHANBSD_SIZEOF_GREGS)
 170     {
 171       if (sect_size >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 172         return &alphanbsd_aout_gregset;
 173       else
 174         return &alphanbsd_gregset;
 175     }
 176
 177   if (strcmp (sect_name, ".reg2") == 0 && sect_size >= ALPHANBSD_SIZEOF_FPREGS)
 178     return &alphanbsd_fpregset;
 179
 180   return NULL;
 181 }
 182 \f
 183
 184 /* Signal trampolines.  */
 185
 186 /* Under NetBSD/alpha, signal handler invocations can be identified by the
 187    designated code sequence that is used to return from a signal handler.
 188    In particular, the return address of a signal handler points to the
 189    following code sequence:
 190
 191         ldq     a0, 0(sp)
 192         lda     sp, 16(sp)
 193         lda     v0, 295(zero)   # __sigreturn14
 194         call_pal callsys
 195
 196    Each instruction has a unique encoding, so we simply attempt to match
 197    the instruction the PC is pointing to with any of the above instructions.
 198    If there is a hit, we know the offset to the start of the designated
 199    sequence and can then check whether we really are executing in the
 200    signal trampoline.  If not, -1 is returned, otherwise the offset from the
 201    start of the return sequence is returned.  */
 202 static const gdb_byte sigtramp_retcode[] =
 203 {
 204   0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */
 205   0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */
 206   0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */
 207   0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */
 208 };
 209 #define RETCODE_NWORDS          4
 210 #define RETCODE_SIZE            (RETCODE_NWORDS * 4)
 211
 212 static LONGEST
 213 alphanbsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
 214 {
 215   gdb_byte ret[RETCODE_SIZE], w[4];
 216   LONGEST off;
 217   int i;
 218
 219   if (target_read_memory (pc, w, 4) != 0)
 220     return -1;
 221
 222   for (i = 0; i < RETCODE_NWORDS; i++)
 223     {
 224       if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
 225         break;
 226     }
 227   if (i == RETCODE_NWORDS)
 228     return (-1);
 229
 230   off = i * 4;
 231   pc -= off;
 232
 233   if (target_read_memory (pc, ret, sizeof (ret)) != 0)
 234     return -1;
 235
 236   if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
 237     return off;
 238
 239   return -1;
 240 }
 241
 242 static int
 243 alphanbsd_pc_in_sigtramp (struct gdbarch *gdbarch,
 244                           CORE_ADDR pc, const char *func_name)
 245 {
 246   return (nbsd_pc_in_sigtramp (pc, func_name)
 247           || alphanbsd_sigtramp_offset (gdbarch, pc) >= 0);
 248 }
 249
 250 static CORE_ADDR
 251 alphanbsd_sigcontext_addr (struct frame_info *frame)
 252 {
 253   /* FIXME: This is not correct for all versions of NetBSD/alpha.
 254      We will probably need to disassemble the trampoline to figure
 255      out which trampoline frame type we have.  */
 256   if (!get_next_frame (frame))
 257     return 0;
 258   return get_frame_base (get_next_frame (frame));
 259 }
 260 \f
 261
 262 static void
 263 alphanbsd_init_abi (struct gdbarch_info info,
 264                     struct gdbarch *gdbarch)
 265 {
 266   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 267
 268   /* Hook into the DWARF CFI frame unwinder.  */
 269   alpha_dwarf2_init_abi (info, gdbarch);
 270
 271   /* Hook into the MDEBUG frame unwinder.  */
 272   alpha_mdebug_init_abi (info, gdbarch);
 273
 274   /* NetBSD/alpha does not provide single step support via ptrace(2); we
 275      must use software single-stepping.  */
 276   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
 277
 278   /* NetBSD/alpha has SVR4-style shared libraries.  */
 279   set_solib_svr4_fetch_link_map_offsets
 280     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 281
 282   tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
 283   tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;
 284   tdep->sigcontext_addr = alphanbsd_sigcontext_addr;
 285
 286   tdep->jb_pc = 2;
 287   tdep->jb_elt_size = 8;
 288
 289   set_gdbarch_regset_from_core_section
 290     (gdbarch, alphanbsd_regset_from_core_section);
 291 }
 292 \f
 293
 294 static enum gdb_osabi
 295 alphanbsd_core_osabi_sniffer (bfd *abfd)
 296 {
 297   if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)
 298     return GDB_OSABI_NETBSD_ELF;
 299
 300   return GDB_OSABI_UNKNOWN;
 301 }
 302 \f
 303
 304 /* Provide a prototype to silence -Wmissing-prototypes.  */
 305 void _initialize_alphanbsd_tdep (void);
 306
 307 void
 308 _initialize_alphanbsd_tdep (void)
 309 {
 310   /* BFD doesn't set a flavour for NetBSD style a.out core files.  */
 311   gdbarch_register_osabi_sniffer (bfd_arch_alpha, bfd_target_unknown_flavour,
 312                                   alphanbsd_core_osabi_sniffer);
 313
 314   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
 315                           alphanbsd_init_abi);
 316 }