gdb/m68klinux-tdep.c

   1 /* Motorola m68k target-dependent support for GNU/Linux.
   2
   3    Copyright (C) 1996, 1998, 2000, 2001, 2002, 2003, 2004, 2007, 2008, 2009,
   4    2010, 2011 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "gdbcore.h"
  23 #include "doublest.h"
  24 #include "floatformat.h"
  25 #include "frame.h"
  26 #include "target.h"
  27 #include "gdb_string.h"
  28 #include "gdbtypes.h"
  29 #include "osabi.h"
  30 #include "regcache.h"
  31 #include "objfiles.h"
  32 #include "symtab.h"
  33 #include "m68k-tdep.h"
  34 #include "trad-frame.h"
  35 #include "frame-unwind.h"
  36 #include "glibc-tdep.h"
  37 #include "solib-svr4.h"
  38 #include "auxv.h"
  39 #include "observer.h"
  40 #include "elf/common.h"
  41 #include "linux-tdep.h"
  42 \f
  43 /* Offsets (in target ints) into jmp_buf.  */
  44
  45 #define M68K_LINUX_JB_ELEMENT_SIZE 4
  46 #define M68K_LINUX_JB_PC 7
  47
  48 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  49
  50 #define IS_SIGTRAMP(insn1, insn2)                                       \
  51   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  52    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  53    /* moveq #119,d0; trap #0 */                                         \
  54    || insn1 == 0x70774e40)
  55
  56 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  57   (/* movel #173,d0; trap #0 */                                         \
  58    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  59    /* moveq #82,d0; notb d0; trap #0 */                                 \
  60    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  61
  62 /* Return non-zero if THIS_FRAME corresponds to a signal trampoline.  For
  63    the sake of m68k_linux_get_sigtramp_info we also distinguish between
  64    non-RT and RT signal trampolines.  */
  65
  66 static int
  67 m68k_linux_pc_in_sigtramp (struct frame_info *this_frame)
  68 {
  69   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  70   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  71   CORE_ADDR sp;
  72   gdb_byte buf[12];
  73   unsigned long insn0, insn1, insn2;
  74   CORE_ADDR pc = get_frame_pc (this_frame);
  75
  76   if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, sizeof (buf)))
  77     return 0;
  78   insn1 = extract_unsigned_integer (buf + 4, 4, byte_order);
  79   insn2 = extract_unsigned_integer (buf + 8, 4, byte_order);
  80   if (IS_SIGTRAMP (insn1, insn2))
  81     return 1;
  82   if (IS_RT_SIGTRAMP (insn1, insn2))
  83     return 2;
  84
  85   insn0 = extract_unsigned_integer (buf, 4, byte_order);
  86   if (IS_SIGTRAMP (insn0, insn1))
  87     return 1;
  88   if (IS_RT_SIGTRAMP (insn0, insn1))
  89     return 2;
  90
  91   insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
  92   insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
  93   if (IS_SIGTRAMP (insn0, insn1))
  94     return 1;
  95   if (IS_RT_SIGTRAMP (insn0, insn1))
  96     return 2;
  97
  98   return 0;
  99 }
 100
 101 /* From <asm/sigcontext.h>.  */
 102 static int m68k_linux_sigcontext_reg_offset[M68K_NUM_REGS] =
 103 {
 104   2 * 4,                        /* %d0 */
 105   3 * 4,                        /* %d1 */
 106   -1,                           /* %d2 */
 107   -1,                           /* %d3 */
 108   -1,                           /* %d4 */
 109   -1,                           /* %d5 */
 110   -1,                           /* %d6 */
 111   -1,                           /* %d7 */
 112   4 * 4,                        /* %a0 */
 113   5 * 4,                        /* %a1 */
 114   -1,                           /* %a2 */
 115   -1,                           /* %a3 */
 116   -1,                           /* %a4 */
 117   -1,                           /* %a5 */
 118   -1,                           /* %fp */
 119   1 * 4,                        /* %sp */
 120   6 * 4,                        /* %sr */
 121   6 * 4 + 2,                    /* %pc */
 122   8 * 4,                        /* %fp0 */
 123   11 * 4,                       /* %fp1 */
 124   -1,                           /* %fp2 */
 125   -1,                           /* %fp3 */
 126   -1,                           /* %fp4 */
 127   -1,                           /* %fp5 */
 128   -1,                           /* %fp6 */
 129   -1,                           /* %fp7 */
 130   14 * 4,                       /* %fpcr */
 131   15 * 4,                       /* %fpsr */
 132   16 * 4                        /* %fpiaddr */
 133 };
 134
 135 static int m68k_uclinux_sigcontext_reg_offset[M68K_NUM_REGS] =
 136 {
 137   2 * 4,                        /* %d0 */
 138   3 * 4,                        /* %d1 */
 139   -1,                           /* %d2 */
 140   -1,                           /* %d3 */
 141   -1,                           /* %d4 */
 142   -1,                           /* %d5 */
 143   -1,                           /* %d6 */
 144   -1,                           /* %d7 */
 145   4 * 4,                        /* %a0 */
 146   5 * 4,                        /* %a1 */
 147   -1,                           /* %a2 */
 148   -1,                           /* %a3 */
 149   -1,                           /* %a4 */
 150   6 * 4,                        /* %a5 */
 151   -1,                           /* %fp */
 152   1 * 4,                        /* %sp */
 153   7 * 4,                        /* %sr */
 154   7 * 4 + 2,                    /* %pc */
 155   -1,                           /* %fp0 */
 156   -1,                           /* %fp1 */
 157   -1,                           /* %fp2 */
 158   -1,                           /* %fp3 */
 159   -1,                           /* %fp4 */
 160   -1,                           /* %fp5 */
 161   -1,                           /* %fp6 */
 162   -1,                           /* %fp7 */
 163   -1,                           /* %fpcr */
 164   -1,                           /* %fpsr */
 165   -1                            /* %fpiaddr */
 166 };
 167
 168 /* From <asm/ucontext.h>.  */
 169 static int m68k_linux_ucontext_reg_offset[M68K_NUM_REGS] =
 170 {
 171   6 * 4,                        /* %d0 */
 172   7 * 4,                        /* %d1 */
 173   8 * 4,                        /* %d2 */
 174   9 * 4,                        /* %d3 */
 175   10 * 4,                       /* %d4 */
 176   11 * 4,                       /* %d5 */
 177   12 * 4,                       /* %d6 */
 178   13 * 4,                       /* %d7 */
 179   14 * 4,                       /* %a0 */
 180   15 * 4,                       /* %a1 */
 181   16 * 4,                       /* %a2 */
 182   17 * 4,                       /* %a3 */
 183   18 * 4,                       /* %a4 */
 184   19 * 4,                       /* %a5 */
 185   20 * 4,                       /* %fp */
 186   21 * 4,                       /* %sp */
 187   23 * 4,                       /* %sr */
 188   22 * 4,                       /* %pc */
 189   27 * 4,                       /* %fp0 */
 190   30 * 4,                       /* %fp1 */
 191   33 * 4,                       /* %fp2 */
 192   36 * 4,                       /* %fp3 */
 193   39 * 4,                       /* %fp4 */
 194   42 * 4,                       /* %fp5 */
 195   45 * 4,                       /* %fp6 */
 196   48 * 4,                       /* %fp7 */
 197   24 * 4,                       /* %fpcr */
 198   25 * 4,                       /* %fpsr */
 199   26 * 4                        /* %fpiaddr */
 200 };
 201
 202
 203 /* Get info about saved registers in sigtramp.  */
 204
 205 struct m68k_linux_sigtramp_info
 206 {
 207   /* Address of sigcontext.  */
 208   CORE_ADDR sigcontext_addr;
 209
 210   /* Offset of registers in `struct sigcontext'.  */
 211   int *sc_reg_offset;
 212 };
 213
 214 /* Nonzero if running on uClinux.  */
 215 static int target_is_uclinux;
 216
 217 static void
 218 m68k_linux_inferior_created (struct target_ops *objfile, int from_tty)
 219 {
 220   /* Record that we will need to re-evaluate whether we are running on a
 221      uClinux or normal GNU/Linux target (see m68k_linux_get_sigtramp_info).  */
 222   target_is_uclinux = -1;
 223 }
 224
 225 static struct m68k_linux_sigtramp_info
 226 m68k_linux_get_sigtramp_info (struct frame_info *this_frame)
 227 {
 228   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 229   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 230   CORE_ADDR sp;
 231   struct m68k_linux_sigtramp_info info;
 232
 233   if (target_is_uclinux == -1)
 234     {
 235       /* Determine whether we are running on a uClinux or normal GNU/Linux
 236          target so we can use the correct sigcontext layouts.  */
 237       CORE_ADDR dummy;
 238
 239       target_is_uclinux
 240         = (target_auxv_search (&current_target, AT_NULL, &dummy) > 0
 241            && target_auxv_search (&current_target, AT_PAGESZ, &dummy) == 0);
 242     }
 243
 244   sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
 245
 246   /* Get sigcontext address, it is the third parameter on the stack.  */
 247   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4, byte_order);
 248
 249   if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
 250     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 251   else
 252     info.sc_reg_offset = (target_is_uclinux
 253                           ? m68k_uclinux_sigcontext_reg_offset
 254                           : m68k_linux_sigcontext_reg_offset);
 255   return info;
 256 }
 257
 258 /* Signal trampolines.  */
 259
 260 static struct trad_frame_cache *
 261 m68k_linux_sigtramp_frame_cache (struct frame_info *this_frame,
 262                                  void **this_cache)
 263 {
 264   struct frame_id this_id;
 265   struct trad_frame_cache *cache;
 266   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 267   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 268   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 269   struct m68k_linux_sigtramp_info info;
 270   gdb_byte buf[4];
 271   int i;
 272
 273   if (*this_cache)
 274     return *this_cache;
 275
 276   cache = trad_frame_cache_zalloc (this_frame);
 277
 278   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 279      The frame ID's code address should be the start-address of the
 280      signal trampoline and not the current PC within that
 281      trampoline.  */
 282   get_frame_register (this_frame, M68K_SP_REGNUM, buf);
 283   /* See the end of m68k_push_dummy_call.  */
 284   this_id = frame_id_build (extract_unsigned_integer (buf, 4, byte_order)
 285                             - 4 + 8, get_frame_pc (this_frame));
 286   trad_frame_set_id (cache, this_id);
 287
 288   info = m68k_linux_get_sigtramp_info (this_frame);
 289
 290   for (i = 0; i < M68K_NUM_REGS; i++)
 291     if (info.sc_reg_offset[i] != -1)
 292       trad_frame_set_reg_addr (cache, i,
 293                                info.sigcontext_addr + info.sc_reg_offset[i]);
 294
 295   *this_cache = cache;
 296   return cache;
 297 }
 298
 299 static void
 300 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 301                                    void **this_cache,
 302                                    struct frame_id *this_id)
 303 {
 304   struct trad_frame_cache *cache =
 305     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 306   trad_frame_get_id (cache, this_id);
 307 }
 308
 309 static struct value *
 310 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 311                                          void **this_cache,
 312                                          int regnum)
 313 {
 314   /* Make sure we've initialized the cache.  */
 315   struct trad_frame_cache *cache =
 316     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 317   return trad_frame_get_register (cache, this_frame, regnum);
 318 }
 319
 320 static int
 321 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 322                                    struct frame_info *this_frame,
 323                                    void **this_prologue_cache)
 324 {
 325   return m68k_linux_pc_in_sigtramp (this_frame);
 326 }
 327
 328 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
 329 {
 330   SIGTRAMP_FRAME,
 331   default_frame_unwind_stop_reason,
 332   m68k_linux_sigtramp_frame_this_id,
 333   m68k_linux_sigtramp_frame_prev_register,
 334   NULL,
 335   m68k_linux_sigtramp_frame_sniffer
 336 };
 337
 338 static void
 339 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 340 {
 341   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 342
 343   linux_init_abi (info, gdbarch);
 344
 345   tdep->jb_pc = M68K_LINUX_JB_PC;
 346   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 347
 348   /* GNU/Linux uses a calling convention that's similar to SVR4.  It
 349      returns integer values in %d0/%d1, pointer values in %a0 and
 350      floating values in %fp0, just like SVR4, but uses %a1 to pass the
 351      address to store a structure value.  It also returns small
 352      structures in registers instead of memory.  */
 353   m68k_svr4_init_abi (info, gdbarch);
 354   tdep->struct_value_regnum = M68K_A1_REGNUM;
 355   tdep->struct_return = reg_struct_return;
 356
 357   set_gdbarch_decr_pc_after_break (gdbarch, 2);
 358
 359   frame_unwind_append_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
 360
 361   /* Shared library handling.  */
 362
 363   /* GNU/Linux uses SVR4-style shared libraries.  */
 364   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 365                                          svr4_ilp32_fetch_link_map_offsets);
 366
 367   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 368   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 369
 370   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 371
 372   /* Enable TLS support.  */
 373   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 374                                              svr4_fetch_objfile_link_map);
 375 }
 376
 377 /* Provide a prototype to silence -Wmissing-prototypes.  */
 378 extern initialize_file_ftype _initialize_m68k_linux_tdep;
 379
 380 void
 381 _initialize_m68k_linux_tdep (void)
 382 {
 383   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 384                           m68k_linux_init_abi);
 385   observer_attach_inferior_created (m68k_linux_inferior_created);
 386 }