gdb/alpha-nbsd-tdep.c

   1 /* Target-dependent code for NetBSD/alpha.
   2
   3    Copyright (C) 2002-2019 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
  24 /* Local non-gdb includes.  */
  25 #include "alpha-bsd-tdep.h"
  26 #include "alpha-tdep.h"
  27 #include "frame.h"
  28 #include "gdbcore.h"
  29 #include "nbsd-tdep.h"
  30 #include "osabi.h"
  31 #include "regcache.h"
  32 #include "regset.h"
  33 #include "solib-svr4.h"
  34 #include "target.h"
  35 #include "value.h"
  36
  37 /* Core file support.  */
  38
  39 /* Sizeof `struct reg' in <machine/reg.h>.  */
  40 #define ALPHANBSD_SIZEOF_GREGS  (32 * 8)
  41
  42 /* Sizeof `struct fpreg' in <machine/reg.h.  */
  43 #define ALPHANBSD_SIZEOF_FPREGS ((32 * 8) + 8)
  44
  45 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
  46    in the floating-point register set REGSET to register cache
  47    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  48
  49 static void
  50 alphanbsd_supply_fpregset (const struct regset *regset,
  51                            struct regcache *regcache,
  52                            int regnum, const void *fpregs, size_t len)
  53 {
  54   const gdb_byte *regs = (const gdb_byte *) fpregs;
  55   int i;
  56
  57   gdb_assert (len >= ALPHANBSD_SIZEOF_FPREGS);
  58
  59   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
  60     {
  61       if (regnum == i || regnum == -1)
  62         regcache->raw_supply (i, regs + (i - ALPHA_FP0_REGNUM) * 8);
  63     }
  64
  65   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
  66     regcache->raw_supply (ALPHA_FPCR_REGNUM, regs + 32 * 8);
  67 }
  68
  69 /* Supply register REGNUM from the buffer specified by GREGS and LEN
  70    in the general-purpose register set REGSET to register cache
  71    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
  72
  73 static void
  74 alphanbsd_aout_supply_gregset (const struct regset *regset,
  75                                struct regcache *regcache,
  76                                int regnum, const void *gregs, size_t len)
  77 {
  78   const gdb_byte *regs = (const gdb_byte *) gregs;
  79   int i;
  80
  81   /* Table to map a GDB register number to a trapframe register index.  */
  82   static const int regmap[] =
  83   {
  84      0,   1,   2,   3,
  85      4,   5,   6,   7,
  86      8,   9,  10,  11,
  87     12,  13,  14,  15,
  88     30,  31,  32,  16,
  89     17,  18,  19,  20,
  90     21,  22,  23,  24,
  91     25,  29,  26
  92   };
  93
  94   gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);
  95
  96   for (i = 0; i < ARRAY_SIZE(regmap); i++)
  97     {
  98       if (regnum == i || regnum == -1)
  99         regcache->raw_supply (i, regs + regmap[i] * 8);
 100     }
 101
 102   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 103     regcache->raw_supply (ALPHA_PC_REGNUM, regs + 31 * 8);
 104
 105   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 106     {
 107       regs += ALPHANBSD_SIZEOF_GREGS;
 108       len -= ALPHANBSD_SIZEOF_GREGS;
 109       alphanbsd_supply_fpregset (regset, regcache, regnum, regs, len);
 110     }
 111 }
 112
 113 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 114    in the general-purpose register set REGSET to register cache
 115    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 116
 117 static void
 118 alphanbsd_supply_gregset (const struct regset *regset,
 119                           struct regcache *regcache,
 120                           int regnum, const void *gregs, size_t len)
 121 {
 122   const gdb_byte *regs = (const gdb_byte *) gregs;
 123   int i;
 124
 125   if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)
 126     {
 127       alphanbsd_aout_supply_gregset (regset, regcache, regnum, gregs, len);
 128       return;
 129     }
 130
 131   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 132     {
 133       if (regnum == i || regnum == -1)
 134         regcache->raw_supply (i, regs + i * 8);
 135     }
 136
 137   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 138     regcache->raw_supply (ALPHA_PC_REGNUM, regs + 31 * 8);
 139 }
 140
 141 /* NetBSD/alpha register sets.  */
 142
 143 static const struct regset alphanbsd_gregset =
 144 {
 145   NULL,
 146   alphanbsd_supply_gregset,
 147   NULL,
 148   REGSET_VARIABLE_SIZE
 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_SIZEOF_GREGS,
 166       &alphanbsd_gregset, NULL, cb_data);
 167   cb (".reg2", ALPHANBSD_SIZEOF_FPREGS, ALPHANBSD_SIZEOF_FPREGS,
 168       &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 void
 283 _initialize_alphanbsd_tdep (void)
 284 {
 285   /* Even though NetBSD/alpha used ELF since day one, it used the
 286      traditional a.out-style core dump format before NetBSD 1.6, but
 287      we don't support those.  */
 288   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD,
 289                           alphanbsd_init_abi);
 290 }