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    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 THIS_FRAME corresponds to a signal trampoline.  For
  62    the 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 (struct frame_info *this_frame)
  67 {
  68   CORE_ADDR sp;
  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);
  76   insn2 = extract_unsigned_integer (buf + 8, 4);
  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);
  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   CORE_ADDR sp;
 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       CORE_ADDR dummy;
 233
 234       target_is_uclinux
 235         = (target_auxv_search (&current_target, AT_NULL, &dummy) > 0
 236            && target_auxv_search (&current_target, AT_PAGESZ, &dummy) == 0);
 237     }
 238
 239   sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
 240
 241   /* Get sigcontext address, it is the third parameter on the stack.  */
 242   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4);
 243
 244   if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
 245     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 246   else
 247     info.sc_reg_offset = (target_is_uclinux
 248                           ? m68k_uclinux_sigcontext_reg_offset
 249                           : m68k_linux_sigcontext_reg_offset);
 250   return info;
 251 }
 252
 253 /* Signal trampolines.  */
 254
 255 static struct trad_frame_cache *
 256 m68k_linux_sigtramp_frame_cache (struct frame_info *this_frame,
 257                                  void **this_cache)
 258 {
 259   struct frame_id this_id;
 260   struct trad_frame_cache *cache;
 261   struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (this_frame));
 262   struct m68k_linux_sigtramp_info info;
 263   gdb_byte buf[4];
 264   int i;
 265
 266   if (*this_cache)
 267     return *this_cache;
 268
 269   cache = trad_frame_cache_zalloc (this_frame);
 270
 271   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 272      The frame ID's code address should be the start-address of the
 273      signal trampoline and not the current PC within that
 274      trampoline.  */
 275   get_frame_register (this_frame, M68K_SP_REGNUM, buf);
 276   /* See the end of m68k_push_dummy_call.  */
 277   this_id = frame_id_build (extract_unsigned_integer (buf, 4) - 4 + 8,
 278                             get_frame_pc (this_frame));
 279   trad_frame_set_id (cache, this_id);
 280
 281   info = m68k_linux_get_sigtramp_info (this_frame);
 282
 283   for (i = 0; i < M68K_NUM_REGS; i++)
 284     if (info.sc_reg_offset[i] != -1)
 285       trad_frame_set_reg_addr (cache, i,
 286                                info.sigcontext_addr + info.sc_reg_offset[i]);
 287
 288   *this_cache = cache;
 289   return cache;
 290 }
 291
 292 static void
 293 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 294                                    void **this_cache,
 295                                    struct frame_id *this_id)
 296 {
 297   struct trad_frame_cache *cache =
 298     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 299   trad_frame_get_id (cache, this_id);
 300 }
 301
 302 static struct value *
 303 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 304                                          void **this_cache,
 305                                          int regnum)
 306 {
 307   /* Make sure we've initialized the cache.  */
 308   struct trad_frame_cache *cache =
 309     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 310   return trad_frame_get_register (cache, this_frame, regnum);
 311 }
 312
 313 static int
 314 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 315                                    struct frame_info *this_frame,
 316                                    void **this_prologue_cache)
 317 {
 318   return m68k_linux_pc_in_sigtramp (this_frame);
 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   NULL,
 327   m68k_linux_sigtramp_frame_sniffer
 328 };
 329
 330 static void
 331 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 332 {
 333   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 334
 335   tdep->jb_pc = M68K_LINUX_JB_PC;
 336   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 337
 338   /* GNU/Linux uses a calling convention that's similar to SVR4.  It
 339      returns integer values in %d0/%d1, pointer values in %a0 and
 340      floating values in %fp0, just like SVR4, but uses %a1 to pass the
 341      address to store a structure value.  It also returns small
 342      structures in registers instead of memory.  */
 343   m68k_svr4_init_abi (info, gdbarch);
 344   tdep->struct_value_regnum = M68K_A1_REGNUM;
 345   tdep->struct_return = reg_struct_return;
 346
 347   set_gdbarch_decr_pc_after_break (gdbarch, 2);
 348
 349   frame_unwind_append_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
 350
 351   /* Shared library handling.  */
 352
 353   /* GNU/Linux uses SVR4-style shared libraries.  */
 354   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 355                                          svr4_ilp32_fetch_link_map_offsets);
 356
 357   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 358   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 359
 360   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 361
 362   /* Enable TLS support.  */
 363   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 364                                              svr4_fetch_objfile_link_map);
 365 }
 366
 367 /* Provide a prototype to silence -Wmissing-prototypes.  */
 368 extern initialize_file_ftype _initialize_m68k_linux_tdep;
 369
 370 void
 371 _initialize_m68k_linux_tdep (void)
 372 {
 373   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 374                           m68k_linux_init_abi);
 375   observer_attach_inferior_created (m68k_linux_inferior_created);
 376 }