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