gdb/m68klinux-tdep.c

   1 /* Motorola m68k target-dependent support for GNU/Linux.
   2
   3    Copyright (C) 1996-2014 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "gdbcore.h"
  22 #include "doublest.h"
  23 #include "floatformat.h"
  24 #include "frame.h"
  25 #include "target.h"
  26 #include "gdbtypes.h"
  27 #include "osabi.h"
  28 #include "regcache.h"
  29 #include "objfiles.h"
  30 #include "symtab.h"
  31 #include "m68k-tdep.h"
  32 #include "trad-frame.h"
  33 #include "frame-unwind.h"
  34 #include "glibc-tdep.h"
  35 #include "solib-svr4.h"
  36 #include "auxv.h"
  37 #include "observer.h"
  38 #include "elf/common.h"
  39 #include "linux-tdep.h"
  40 \f
  41 /* Offsets (in target ints) into jmp_buf.  */
  42
  43 #define M68K_LINUX_JB_ELEMENT_SIZE 4
  44 #define M68K_LINUX_JB_PC 7
  45
  46 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  47
  48 #define IS_SIGTRAMP(insn1, insn2)                                       \
  49   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  50    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  51    /* moveq #119,d0; trap #0 */                                         \
  52    || insn1 == 0x70774e40)
  53
  54 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  55   (/* movel #173,d0; trap #0 */                                         \
  56    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  57    /* moveq #82,d0; notb d0; trap #0 */                                 \
  58    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  59
  60 /* Return non-zero if THIS_FRAME corresponds to a signal trampoline.  For
  61    the sake of m68k_linux_get_sigtramp_info we also distinguish between
  62    non-RT and RT signal trampolines.  */
  63
  64 static int
  65 m68k_linux_pc_in_sigtramp (struct frame_info *this_frame)
  66 {
  67   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  68   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  69   gdb_byte buf[12];
  70   unsigned long insn0, insn1, insn2;
  71   CORE_ADDR pc = get_frame_pc (this_frame);
  72
  73   if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, sizeof (buf)))
  74     return 0;
  75   insn1 = extract_unsigned_integer (buf + 4, 4, byte_order);
  76   insn2 = extract_unsigned_integer (buf + 8, 4, byte_order);
  77   if (IS_SIGTRAMP (insn1, insn2))
  78     return 1;
  79   if (IS_RT_SIGTRAMP (insn1, insn2))
  80     return 2;
  81
  82   insn0 = extract_unsigned_integer (buf, 4, byte_order);
  83   if (IS_SIGTRAMP (insn0, insn1))
  84     return 1;
  85   if (IS_RT_SIGTRAMP (insn0, insn1))
  86     return 2;
  87
  88   insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
  89   insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
  90   if (IS_SIGTRAMP (insn0, insn1))
  91     return 1;
  92   if (IS_RT_SIGTRAMP (insn0, insn1))
  93     return 2;
  94
  95   return 0;
  96 }
  97
  98 /* From <asm/sigcontext.h>.  */
  99 static int m68k_linux_sigcontext_reg_offset[M68K_NUM_REGS] =
 100 {
 101   2 * 4,                        /* %d0 */
 102   3 * 4,                        /* %d1 */
 103   -1,                           /* %d2 */
 104   -1,                           /* %d3 */
 105   -1,                           /* %d4 */
 106   -1,                           /* %d5 */
 107   -1,                           /* %d6 */
 108   -1,                           /* %d7 */
 109   4 * 4,                        /* %a0 */
 110   5 * 4,                        /* %a1 */
 111   -1,                           /* %a2 */
 112   -1,                           /* %a3 */
 113   -1,                           /* %a4 */
 114   -1,                           /* %a5 */
 115   -1,                           /* %fp */
 116   1 * 4,                        /* %sp */
 117   6 * 4,                        /* %sr */
 118   6 * 4 + 2,                    /* %pc */
 119   8 * 4,                        /* %fp0 */
 120   11 * 4,                       /* %fp1 */
 121   -1,                           /* %fp2 */
 122   -1,                           /* %fp3 */
 123   -1,                           /* %fp4 */
 124   -1,                           /* %fp5 */
 125   -1,                           /* %fp6 */
 126   -1,                           /* %fp7 */
 127   14 * 4,                       /* %fpcr */
 128   15 * 4,                       /* %fpsr */
 129   16 * 4                        /* %fpiaddr */
 130 };
 131
 132 static int m68k_uclinux_sigcontext_reg_offset[M68K_NUM_REGS] =
 133 {
 134   2 * 4,                        /* %d0 */
 135   3 * 4,                        /* %d1 */
 136   -1,                           /* %d2 */
 137   -1,                           /* %d3 */
 138   -1,                           /* %d4 */
 139   -1,                           /* %d5 */
 140   -1,                           /* %d6 */
 141   -1,                           /* %d7 */
 142   4 * 4,                        /* %a0 */
 143   5 * 4,                        /* %a1 */
 144   -1,                           /* %a2 */
 145   -1,                           /* %a3 */
 146   -1,                           /* %a4 */
 147   6 * 4,                        /* %a5 */
 148   -1,                           /* %fp */
 149   1 * 4,                        /* %sp */
 150   7 * 4,                        /* %sr */
 151   7 * 4 + 2,                    /* %pc */
 152   -1,                           /* %fp0 */
 153   -1,                           /* %fp1 */
 154   -1,                           /* %fp2 */
 155   -1,                           /* %fp3 */
 156   -1,                           /* %fp4 */
 157   -1,                           /* %fp5 */
 158   -1,                           /* %fp6 */
 159   -1,                           /* %fp7 */
 160   -1,                           /* %fpcr */
 161   -1,                           /* %fpsr */
 162   -1                            /* %fpiaddr */
 163 };
 164
 165 /* From <asm/ucontext.h>.  */
 166 static int m68k_linux_ucontext_reg_offset[M68K_NUM_REGS] =
 167 {
 168   6 * 4,                        /* %d0 */
 169   7 * 4,                        /* %d1 */
 170   8 * 4,                        /* %d2 */
 171   9 * 4,                        /* %d3 */
 172   10 * 4,                       /* %d4 */
 173   11 * 4,                       /* %d5 */
 174   12 * 4,                       /* %d6 */
 175   13 * 4,                       /* %d7 */
 176   14 * 4,                       /* %a0 */
 177   15 * 4,                       /* %a1 */
 178   16 * 4,                       /* %a2 */
 179   17 * 4,                       /* %a3 */
 180   18 * 4,                       /* %a4 */
 181   19 * 4,                       /* %a5 */
 182   20 * 4,                       /* %fp */
 183   21 * 4,                       /* %sp */
 184   23 * 4,                       /* %sr */
 185   22 * 4,                       /* %pc */
 186   27 * 4,                       /* %fp0 */
 187   30 * 4,                       /* %fp1 */
 188   33 * 4,                       /* %fp2 */
 189   36 * 4,                       /* %fp3 */
 190   39 * 4,                       /* %fp4 */
 191   42 * 4,                       /* %fp5 */
 192   45 * 4,                       /* %fp6 */
 193   48 * 4,                       /* %fp7 */
 194   24 * 4,                       /* %fpcr */
 195   25 * 4,                       /* %fpsr */
 196   26 * 4                        /* %fpiaddr */
 197 };
 198
 199
 200 /* Get info about saved registers in sigtramp.  */
 201
 202 struct m68k_linux_sigtramp_info
 203 {
 204   /* Address of sigcontext.  */
 205   CORE_ADDR sigcontext_addr;
 206
 207   /* Offset of registers in `struct sigcontext'.  */
 208   int *sc_reg_offset;
 209 };
 210
 211 /* Nonzero if running on uClinux.  */
 212 static int target_is_uclinux;
 213
 214 static void
 215 m68k_linux_inferior_created (struct target_ops *objfile, int from_tty)
 216 {
 217   /* Record that we will need to re-evaluate whether we are running on a
 218      uClinux or normal GNU/Linux target (see m68k_linux_get_sigtramp_info).  */
 219   target_is_uclinux = -1;
 220 }
 221
 222 static struct m68k_linux_sigtramp_info
 223 m68k_linux_get_sigtramp_info (struct frame_info *this_frame)
 224 {
 225   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 226   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 227   CORE_ADDR sp;
 228   struct m68k_linux_sigtramp_info info;
 229
 230   /* Determine whether we are running on a uClinux or normal GNU/Linux
 231      target so we can use the correct sigcontext layouts.  */
 232   if (target_is_uclinux == -1)
 233     target_is_uclinux = linux_is_uclinux ();
 234
 235   sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
 236
 237   /* Get sigcontext address, it is the third parameter on the stack.  */
 238   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4, byte_order);
 239
 240   if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
 241     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 242   else
 243     info.sc_reg_offset = (target_is_uclinux
 244                           ? m68k_uclinux_sigcontext_reg_offset
 245                           : m68k_linux_sigcontext_reg_offset);
 246   return info;
 247 }
 248
 249 /* Signal trampolines.  */
 250
 251 static struct trad_frame_cache *
 252 m68k_linux_sigtramp_frame_cache (struct frame_info *this_frame,
 253                                  void **this_cache)
 254 {
 255   struct frame_id this_id;
 256   struct trad_frame_cache *cache;
 257   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 258   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 259   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 260   struct m68k_linux_sigtramp_info info;
 261   gdb_byte buf[4];
 262   int i;
 263
 264   if (*this_cache)
 265     return *this_cache;
 266
 267   cache = trad_frame_cache_zalloc (this_frame);
 268
 269   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 270      The frame ID's code address should be the start-address of the
 271      signal trampoline and not the current PC within that
 272      trampoline.  */
 273   get_frame_register (this_frame, M68K_SP_REGNUM, buf);
 274   /* See the end of m68k_push_dummy_call.  */
 275   this_id = frame_id_build (extract_unsigned_integer (buf, 4, byte_order)
 276                             - 4 + 8, get_frame_pc (this_frame));
 277   trad_frame_set_id (cache, this_id);
 278
 279   info = m68k_linux_get_sigtramp_info (this_frame);
 280
 281   for (i = 0; i < M68K_NUM_REGS; i++)
 282     if (info.sc_reg_offset[i] != -1)
 283       trad_frame_set_reg_addr (cache, i,
 284                                info.sigcontext_addr + info.sc_reg_offset[i]);
 285
 286   *this_cache = cache;
 287   return cache;
 288 }
 289
 290 static void
 291 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 292                                    void **this_cache,
 293                                    struct frame_id *this_id)
 294 {
 295   struct trad_frame_cache *cache =
 296     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 297   trad_frame_get_id (cache, this_id);
 298 }
 299
 300 static struct value *
 301 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 302                                          void **this_cache,
 303                                          int regnum)
 304 {
 305   /* Make sure we've initialized the cache.  */
 306   struct trad_frame_cache *cache =
 307     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 308   return trad_frame_get_register (cache, this_frame, regnum);
 309 }
 310
 311 static int
 312 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 313                                    struct frame_info *this_frame,
 314                                    void **this_prologue_cache)
 315 {
 316   return m68k_linux_pc_in_sigtramp (this_frame);
 317 }
 318
 319 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
 320 {
 321   SIGTRAMP_FRAME,
 322   default_frame_unwind_stop_reason,
 323   m68k_linux_sigtramp_frame_this_id,
 324   m68k_linux_sigtramp_frame_prev_register,
 325   NULL,
 326   m68k_linux_sigtramp_frame_sniffer
 327 };
 328
 329 static void
 330 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 331 {
 332   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 333
 334   linux_init_abi (info, gdbarch);
 335
 336   tdep->jb_pc = M68K_LINUX_JB_PC;
 337   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 338
 339   /* GNU/Linux uses a calling convention that's similar to SVR4.  It
 340      returns integer values in %d0/%d1, pointer values in %a0 and
 341      floating values in %fp0, just like SVR4, but uses %a1 to pass the
 342      address to store a structure value.  It also returns small
 343      structures in registers instead of memory.  */
 344   m68k_svr4_init_abi (info, gdbarch);
 345   tdep->struct_value_regnum = M68K_A1_REGNUM;
 346   tdep->struct_return = reg_struct_return;
 347
 348   set_gdbarch_decr_pc_after_break (gdbarch, 2);
 349
 350   frame_unwind_append_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
 351
 352   /* Shared library handling.  */
 353
 354   /* GNU/Linux uses SVR4-style shared libraries.  */
 355   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 356                                          svr4_ilp32_fetch_link_map_offsets);
 357
 358   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 359   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 360
 361   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 362
 363   /* Enable TLS support.  */
 364   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 365                                              svr4_fetch_objfile_link_map);
 366
 367   set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type);
 368 }
 369
 370 /* Provide a prototype to silence -Wmissing-prototypes.  */
 371 extern initialize_file_ftype _initialize_m68k_linux_tdep;
 372
 373 void
 374 _initialize_m68k_linux_tdep (void)
 375 {
 376   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 377                           m68k_linux_init_abi);
 378   observer_attach_inferior_created (m68k_linux_inferior_created);
 379 }