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
   4    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 2 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, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include "defs.h"
  24 #include "gdbcore.h"
  25 #include "doublest.h"
  26 #include "floatformat.h"
  27 #include "frame.h"
  28 #include "target.h"
  29 #include "gdb_string.h"
  30 #include "gdbtypes.h"
  31 #include "osabi.h"
  32 #include "regcache.h"
  33 #include "objfiles.h"
  34 #include "symtab.h"
  35 #include "m68k-tdep.h"
  36 #include "trad-frame.h"
  37 #include "frame-unwind.h"
  38 #include "glibc-tdep.h"
  39 #include "solib-svr4.h"
  40 #include "auxv.h"
  41 #include "observer.h"
  42 #include "elf/common.h"
  43 \f
  44 /* Offsets (in target ints) into jmp_buf.  */
  45
  46 #define M68K_LINUX_JB_ELEMENT_SIZE 4
  47 #define M68K_LINUX_JB_PC 7
  48
  49 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  50
  51 #define IS_SIGTRAMP(insn1, insn2)                                       \
  52   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  53    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  54    /* moveq #119,d0; trap #0 */                                         \
  55    || insn1 == 0x70774e40)
  56
  57 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  58   (/* movel #173,d0; trap #0 */                                         \
  59    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  60    /* moveq #82,d0; notb d0; trap #0 */                                 \
  61    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  62
  63 /* Return non-zero if PC points into the signal trampoline.  For the
  64    sake of m68k_linux_get_sigtramp_info we also distinguish between
  65    non-RT and RT signal trampolines.  */
  66
  67 static int
  68 m68k_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
  69 {
  70   CORE_ADDR sp;
  71   char buf[12];
  72   unsigned long insn0, insn1, insn2;
  73
  74   if (read_memory_nobpt (pc - 4, buf, sizeof (buf)))
  75     return 0;
  76   insn1 = extract_unsigned_integer (buf + 4, 4);
  77   insn2 = extract_unsigned_integer (buf + 8, 4);
  78   if (IS_SIGTRAMP (insn1, insn2))
  79     return 1;
  80   if (IS_RT_SIGTRAMP (insn1, insn2))
  81     return 2;
  82
  83   insn0 = extract_unsigned_integer (buf, 4);
  84   if (IS_SIGTRAMP (insn0, insn1))
  85     return 1;
  86   if (IS_RT_SIGTRAMP (insn0, insn1))
  87     return 2;
  88
  89   insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
  90   insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
  91   if (IS_SIGTRAMP (insn0, insn1))
  92     return 1;
  93   if (IS_RT_SIGTRAMP (insn0, insn1))
  94     return 2;
  95
  96   return 0;
  97 }
  98
  99 /* From <asm/sigcontext.h>.  */
 100 static int m68k_linux_sigcontext_reg_offset[M68K_NUM_REGS] =
 101 {
 102   2 * 4,                        /* %d0 */
 103   3 * 4,                        /* %d1 */
 104   -1,                           /* %d2 */
 105   -1,                           /* %d3 */
 106   -1,                           /* %d4 */
 107   -1,                           /* %d5 */
 108   -1,                           /* %d6 */
 109   -1,                           /* %d7 */
 110   4 * 4,                        /* %a0 */
 111   5 * 4,                        /* %a1 */
 112   -1,                           /* %a2 */
 113   -1,                           /* %a3 */
 114   -1,                           /* %a4 */
 115   -1,                           /* %a5 */
 116   -1,                           /* %fp */
 117   1 * 4,                        /* %sp */
 118   6 * 4,                        /* %sr */
 119   6 * 4 + 2,                    /* %pc */
 120   8 * 4,                        /* %fp0 */
 121   11 * 4,                       /* %fp1 */
 122   -1,                           /* %fp2 */
 123   -1,                           /* %fp3 */
 124   -1,                           /* %fp4 */
 125   -1,                           /* %fp5 */
 126   -1,                           /* %fp6 */
 127   -1,                           /* %fp7 */
 128   14 * 4,                       /* %fpcr */
 129   15 * 4,                       /* %fpsr */
 130   16 * 4                        /* %fpiaddr */
 131 };
 132
 133 static int m68k_uclinux_sigcontext_reg_offset[M68K_NUM_REGS] =
 134 {
 135   2 * 4,                        /* %d0 */
 136   3 * 4,                        /* %d1 */
 137   -1,                           /* %d2 */
 138   -1,                           /* %d3 */
 139   -1,                           /* %d4 */
 140   -1,                           /* %d5 */
 141   -1,                           /* %d6 */
 142   -1,                           /* %d7 */
 143   4 * 4,                        /* %a0 */
 144   5 * 4,                        /* %a1 */
 145   -1,                           /* %a2 */
 146   -1,                           /* %a3 */
 147   -1,                           /* %a4 */
 148   6 * 4,                        /* %a5 */
 149   -1,                           /* %fp */
 150   1 * 4,                        /* %sp */
 151   7 * 4,                        /* %sr */
 152   7 * 4 + 2,                    /* %pc */
 153   -1,                           /* %fp0 */
 154   -1,                           /* %fp1 */
 155   -1,                           /* %fp2 */
 156   -1,                           /* %fp3 */
 157   -1,                           /* %fp4 */
 158   -1,                           /* %fp5 */
 159   -1,                           /* %fp6 */
 160   -1,                           /* %fp7 */
 161   -1,                           /* %fpcr */
 162   -1,                           /* %fpsr */
 163   -1                            /* %fpiaddr */
 164 };
 165
 166 /* From <asm/ucontext.h>.  */
 167 static int m68k_linux_ucontext_reg_offset[M68K_NUM_REGS] =
 168 {
 169   6 * 4,                        /* %d0 */
 170   7 * 4,                        /* %d1 */
 171   8 * 4,                        /* %d2 */
 172   9 * 4,                        /* %d3 */
 173   10 * 4,                       /* %d4 */
 174   11 * 4,                       /* %d5 */
 175   12 * 4,                       /* %d6 */
 176   13 * 4,                       /* %d7 */
 177   14 * 4,                       /* %a0 */
 178   15 * 4,                       /* %a1 */
 179   16 * 4,                       /* %a2 */
 180   17 * 4,                       /* %a3 */
 181   18 * 4,                       /* %a4 */
 182   19 * 4,                       /* %a5 */
 183   20 * 4,                       /* %fp */
 184   21 * 4,                       /* %sp */
 185   23 * 4,                       /* %sr */
 186   22 * 4,                       /* %pc */
 187   27 * 4,                       /* %fp0 */
 188   30 * 4,                       /* %fp1 */
 189   33 * 4,                       /* %fp2 */
 190   36 * 4,                       /* %fp3 */
 191   39 * 4,                       /* %fp4 */
 192   42 * 4,                       /* %fp5 */
 193   45 * 4,                       /* %fp6 */
 194   48 * 4,                       /* %fp7 */
 195   24 * 4,                       /* %fpcr */
 196   25 * 4,                       /* %fpsr */
 197   26 * 4                        /* %fpiaddr */
 198 };
 199
 200
 201 /* Get info about saved registers in sigtramp.  */
 202
 203 struct m68k_linux_sigtramp_info
 204 {
 205   /* Address of sigcontext.  */
 206   CORE_ADDR sigcontext_addr;
 207
 208   /* Offset of registers in `struct sigcontext'.  */
 209   int *sc_reg_offset;
 210 };
 211
 212 /* Nonzero if running on uClinux.  */
 213 static int target_is_uclinux;
 214
 215 static void
 216 m68k_linux_inferior_created (struct target_ops *objfile, int from_tty)
 217 {
 218   /* Record that we will need to re-evaluate whether we are running on
 219      a uClinux or normal Linux target (see m68k_linux_get_sigtramp_info).  */
 220   target_is_uclinux = -1;
 221 }
 222
 223 static struct m68k_linux_sigtramp_info
 224 m68k_linux_get_sigtramp_info (struct frame_info *next_frame)
 225 {
 226   CORE_ADDR sp;
 227   char buf[4];
 228   struct m68k_linux_sigtramp_info info;
 229
 230   if (target_is_uclinux == -1)
 231     {
 232       /* Determine whether we are running on a uClinux or normal Linux
 233          target so we can use the correct sigcontext layouts.  */
 234
 235       CORE_ADDR dummy;
 236
 237       target_is_uclinux
 238         = target_auxv_search (&current_target, AT_NULL, &dummy) > 0
 239           && target_auxv_search (&current_target, AT_PAGESZ, &dummy) == 0;
 240     }
 241
 242   frame_unwind_register (next_frame, M68K_SP_REGNUM, buf);
 243   sp = extract_unsigned_integer (buf, 4);
 244
 245   /* Get sigcontext address, it is the third parameter on the stack.  */
 246   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4);
 247
 248   if (m68k_linux_pc_in_sigtramp (frame_pc_unwind (next_frame), 0) == 2)
 249     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 250   else
 251     info.sc_reg_offset
 252       = target_is_uclinux ? m68k_uclinux_sigcontext_reg_offset
 253                           : m68k_linux_sigcontext_reg_offset;
 254   return info;
 255 }
 256
 257 /* Signal trampolines.  */
 258
 259 static struct trad_frame_cache *
 260 m68k_linux_sigtramp_frame_cache (struct frame_info *next_frame,
 261                                  void **this_cache)
 262 {
 263   struct frame_id this_id;
 264   struct trad_frame_cache *cache;
 265   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 266   struct m68k_linux_sigtramp_info info;
 267   char buf[4];
 268   int i;
 269
 270   if (*this_cache)
 271     return *this_cache;
 272
 273   cache = trad_frame_cache_zalloc (next_frame);
 274
 275   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 276      The frame ID's code address should be the start-address of the
 277      signal trampoline and not the current PC within that
 278      trampoline.  */
 279   frame_unwind_register (next_frame, M68K_SP_REGNUM, buf);
 280   /* See the end of m68k_push_dummy_call.  */
 281   this_id = frame_id_build (extract_unsigned_integer (buf, 4) - 4 + 8,
 282                             frame_pc_unwind (next_frame));
 283   trad_frame_set_id (cache, this_id);
 284
 285   info = m68k_linux_get_sigtramp_info (next_frame);
 286
 287   for (i = 0; i < M68K_NUM_REGS; i++)
 288     if (info.sc_reg_offset[i] != -1)
 289       trad_frame_set_reg_addr (cache, i,
 290                                info.sigcontext_addr + info.sc_reg_offset[i]);
 291
 292   *this_cache = cache;
 293   return cache;
 294 }
 295
 296 static void
 297 m68k_linux_sigtramp_frame_this_id (struct frame_info *next_frame,
 298                                    void **this_cache,
 299                                    struct frame_id *this_id)
 300 {
 301   struct trad_frame_cache *cache =
 302     m68k_linux_sigtramp_frame_cache (next_frame, this_cache);
 303   trad_frame_get_id (cache, this_id);
 304 }
 305
 306 static void
 307 m68k_linux_sigtramp_frame_prev_register (struct frame_info *next_frame,
 308                                          void **this_cache,
 309                                          int regnum, int *optimizedp,
 310                                          enum lval_type *lvalp,
 311                                          CORE_ADDR *addrp,
 312                                          int *realnump, gdb_byte *valuep)
 313 {
 314   /* Make sure we've initialized the cache.  */
 315   struct trad_frame_cache *cache =
 316     m68k_linux_sigtramp_frame_cache (next_frame, this_cache);
 317   trad_frame_get_register (cache, next_frame, regnum, optimizedp, lvalp,
 318                            addrp, realnump, valuep);
 319 }
 320
 321 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
 322 {
 323   SIGTRAMP_FRAME,
 324   m68k_linux_sigtramp_frame_this_id,
 325   m68k_linux_sigtramp_frame_prev_register
 326 };
 327
 328 static const struct frame_unwind *
 329 m68k_linux_sigtramp_frame_sniffer (struct frame_info *next_frame)
 330 {
 331   CORE_ADDR pc = frame_pc_unwind (next_frame);
 332   char *name;
 333
 334   find_pc_partial_function (pc, &name, NULL, NULL);
 335   if (m68k_linux_pc_in_sigtramp (pc, name))
 336     return &m68k_linux_sigtramp_frame_unwind;
 337
 338   return NULL;
 339 }
 340
 341 static void
 342 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 343 {
 344   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 345
 346   tdep->jb_pc = M68K_LINUX_JB_PC;
 347   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 348
 349   /* GNU/Linux uses a calling convention that's similar to SVR4.  It
 350      returns integer values in %d0/%d1, pointer values in %a0 and
 351      floating values in %fp0, just like SVR4, but uses %a1 to pass the
 352      address to store a structure value.  It also returns small
 353      structures in registers instead of memory.  */
 354   m68k_svr4_init_abi (info, gdbarch);
 355   tdep->struct_value_regnum = M68K_A1_REGNUM;
 356   tdep->struct_return = reg_struct_return;
 357
 358   set_gdbarch_decr_pc_after_break (gdbarch, 2);
 359
 360   frame_unwind_append_sniffer (gdbarch, m68k_linux_sigtramp_frame_sniffer);
 361
 362   /* Shared library handling.  */
 363
 364   /* GNU/Linux uses SVR4-style shared libraries.  */
 365   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 366                                          svr4_ilp32_fetch_link_map_offsets);
 367
 368   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 369   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 370
 371   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 372
 373   /* Enable TLS support.  */
 374   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 375                                              svr4_fetch_objfile_link_map);
 376 }
 377
 378 void
 379 _initialize_m68k_linux_tdep (void)
 380 {
 381   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 382                           m68k_linux_init_abi);
 383   observer_attach_inferior_created (m68k_linux_inferior_created);
 384 }