gdb/m68klinux-tdep.c

   1 /* Motorola m68k target-dependent support for GNU/Linux.
   2
   3    Copyright (C) 1996, 1998, 2000-2004, 2007-2012 Free Software
   4    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   gdb_byte buf[12];
  72   unsigned long insn0, insn1, insn2;
  73   CORE_ADDR pc = get_frame_pc (this_frame);
  74
  75   if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, sizeof (buf)))
  76     return 0;
  77   insn1 = extract_unsigned_integer (buf + 4, 4, byte_order);
  78   insn2 = extract_unsigned_integer (buf + 8, 4, byte_order);
  79   if (IS_SIGTRAMP (insn1, insn2))
  80     return 1;
  81   if (IS_RT_SIGTRAMP (insn1, insn2))
  82     return 2;
  83
  84   insn0 = extract_unsigned_integer (buf, 4, byte_order);
  85   if (IS_SIGTRAMP (insn0, insn1))
  86     return 1;
  87   if (IS_RT_SIGTRAMP (insn0, insn1))
  88     return 2;
  89
  90   insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
  91   insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
  92   if (IS_SIGTRAMP (insn0, insn1))
  93     return 1;
  94   if (IS_RT_SIGTRAMP (insn0, insn1))
  95     return 2;
  96
  97   return 0;
  98 }
  99
 100 /* From <asm/sigcontext.h>.  */
 101 static int m68k_linux_sigcontext_reg_offset[M68K_NUM_REGS] =
 102 {
 103   2 * 4,                        /* %d0 */
 104   3 * 4,                        /* %d1 */
 105   -1,                           /* %d2 */
 106   -1,                           /* %d3 */
 107   -1,                           /* %d4 */
 108   -1,                           /* %d5 */
 109   -1,                           /* %d6 */
 110   -1,                           /* %d7 */
 111   4 * 4,                        /* %a0 */
 112   5 * 4,                        /* %a1 */
 113   -1,                           /* %a2 */
 114   -1,                           /* %a3 */
 115   -1,                           /* %a4 */
 116   -1,                           /* %a5 */
 117   -1,                           /* %fp */
 118   1 * 4,                        /* %sp */
 119   6 * 4,                        /* %sr */
 120   6 * 4 + 2,                    /* %pc */
 121   8 * 4,                        /* %fp0 */
 122   11 * 4,                       /* %fp1 */
 123   -1,                           /* %fp2 */
 124   -1,                           /* %fp3 */
 125   -1,                           /* %fp4 */
 126   -1,                           /* %fp5 */
 127   -1,                           /* %fp6 */
 128   -1,                           /* %fp7 */
 129   14 * 4,                       /* %fpcr */
 130   15 * 4,                       /* %fpsr */
 131   16 * 4                        /* %fpiaddr */
 132 };
 133
 134 static int m68k_uclinux_sigcontext_reg_offset[M68K_NUM_REGS] =
 135 {
 136   2 * 4,                        /* %d0 */
 137   3 * 4,                        /* %d1 */
 138   -1,                           /* %d2 */
 139   -1,                           /* %d3 */
 140   -1,                           /* %d4 */
 141   -1,                           /* %d5 */
 142   -1,                           /* %d6 */
 143   -1,                           /* %d7 */
 144   4 * 4,                        /* %a0 */
 145   5 * 4,                        /* %a1 */
 146   -1,                           /* %a2 */
 147   -1,                           /* %a3 */
 148   -1,                           /* %a4 */
 149   6 * 4,                        /* %a5 */
 150   -1,                           /* %fp */
 151   1 * 4,                        /* %sp */
 152   7 * 4,                        /* %sr */
 153   7 * 4 + 2,                    /* %pc */
 154   -1,                           /* %fp0 */
 155   -1,                           /* %fp1 */
 156   -1,                           /* %fp2 */
 157   -1,                           /* %fp3 */
 158   -1,                           /* %fp4 */
 159   -1,                           /* %fp5 */
 160   -1,                           /* %fp6 */
 161   -1,                           /* %fp7 */
 162   -1,                           /* %fpcr */
 163   -1,                           /* %fpsr */
 164   -1                            /* %fpiaddr */
 165 };
 166
 167 /* From <asm/ucontext.h>.  */
 168 static int m68k_linux_ucontext_reg_offset[M68K_NUM_REGS] =
 169 {
 170   6 * 4,                        /* %d0 */
 171   7 * 4,                        /* %d1 */
 172   8 * 4,                        /* %d2 */
 173   9 * 4,                        /* %d3 */
 174   10 * 4,                       /* %d4 */
 175   11 * 4,                       /* %d5 */
 176   12 * 4,                       /* %d6 */
 177   13 * 4,                       /* %d7 */
 178   14 * 4,                       /* %a0 */
 179   15 * 4,                       /* %a1 */
 180   16 * 4,                       /* %a2 */
 181   17 * 4,                       /* %a3 */
 182   18 * 4,                       /* %a4 */
 183   19 * 4,                       /* %a5 */
 184   20 * 4,                       /* %fp */
 185   21 * 4,                       /* %sp */
 186   23 * 4,                       /* %sr */
 187   22 * 4,                       /* %pc */
 188   27 * 4,                       /* %fp0 */
 189   30 * 4,                       /* %fp1 */
 190   33 * 4,                       /* %fp2 */
 191   36 * 4,                       /* %fp3 */
 192   39 * 4,                       /* %fp4 */
 193   42 * 4,                       /* %fp5 */
 194   45 * 4,                       /* %fp6 */
 195   48 * 4,                       /* %fp7 */
 196   24 * 4,                       /* %fpcr */
 197   25 * 4,                       /* %fpsr */
 198   26 * 4                        /* %fpiaddr */
 199 };
 200
 201
 202 /* Get info about saved registers in sigtramp.  */
 203
 204 struct m68k_linux_sigtramp_info
 205 {
 206   /* Address of sigcontext.  */
 207   CORE_ADDR sigcontext_addr;
 208
 209   /* Offset of registers in `struct sigcontext'.  */
 210   int *sc_reg_offset;
 211 };
 212
 213 /* Nonzero if running on uClinux.  */
 214 static int target_is_uclinux;
 215
 216 static void
 217 m68k_linux_inferior_created (struct target_ops *objfile, int from_tty)
 218 {
 219   /* Record that we will need to re-evaluate whether we are running on a
 220      uClinux or normal GNU/Linux target (see m68k_linux_get_sigtramp_info).  */
 221   target_is_uclinux = -1;
 222 }
 223
 224 static struct m68k_linux_sigtramp_info
 225 m68k_linux_get_sigtramp_info (struct frame_info *this_frame)
 226 {
 227   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 228   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 229   CORE_ADDR sp;
 230   struct m68k_linux_sigtramp_info info;
 231
 232   if (target_is_uclinux == -1)
 233     {
 234       /* Determine whether we are running on a uClinux or normal GNU/Linux
 235          target so we can use the correct sigcontext layouts.  */
 236       CORE_ADDR dummy;
 237
 238       target_is_uclinux
 239         = (target_auxv_search (&current_target, AT_NULL, &dummy) > 0
 240            && target_auxv_search (&current_target, AT_PAGESZ, &dummy) == 0);
 241     }
 242
 243   sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
 244
 245   /* Get sigcontext address, it is the third parameter on the stack.  */
 246   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4, byte_order);
 247
 248   if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
 249     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 250   else
 251     info.sc_reg_offset = (target_is_uclinux
 252                           ? 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 *this_frame,
 261                                  void **this_cache)
 262 {
 263   struct frame_id this_id;
 264   struct trad_frame_cache *cache;
 265   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 266   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 267   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 268   struct m68k_linux_sigtramp_info info;
 269   gdb_byte buf[4];
 270   int i;
 271
 272   if (*this_cache)
 273     return *this_cache;
 274
 275   cache = trad_frame_cache_zalloc (this_frame);
 276
 277   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 278      The frame ID's code address should be the start-address of the
 279      signal trampoline and not the current PC within that
 280      trampoline.  */
 281   get_frame_register (this_frame, M68K_SP_REGNUM, buf);
 282   /* See the end of m68k_push_dummy_call.  */
 283   this_id = frame_id_build (extract_unsigned_integer (buf, 4, byte_order)
 284                             - 4 + 8, get_frame_pc (this_frame));
 285   trad_frame_set_id (cache, this_id);
 286
 287   info = m68k_linux_get_sigtramp_info (this_frame);
 288
 289   for (i = 0; i < M68K_NUM_REGS; i++)
 290     if (info.sc_reg_offset[i] != -1)
 291       trad_frame_set_reg_addr (cache, i,
 292                                info.sigcontext_addr + info.sc_reg_offset[i]);
 293
 294   *this_cache = cache;
 295   return cache;
 296 }
 297
 298 static void
 299 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 300                                    void **this_cache,
 301                                    struct frame_id *this_id)
 302 {
 303   struct trad_frame_cache *cache =
 304     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 305   trad_frame_get_id (cache, this_id);
 306 }
 307
 308 static struct value *
 309 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 310                                          void **this_cache,
 311                                          int regnum)
 312 {
 313   /* Make sure we've initialized the cache.  */
 314   struct trad_frame_cache *cache =
 315     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 316   return trad_frame_get_register (cache, this_frame, regnum);
 317 }
 318
 319 static int
 320 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 321                                    struct frame_info *this_frame,
 322                                    void **this_prologue_cache)
 323 {
 324   return m68k_linux_pc_in_sigtramp (this_frame);
 325 }
 326
 327 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
 328 {
 329   SIGTRAMP_FRAME,
 330   default_frame_unwind_stop_reason,
 331   m68k_linux_sigtramp_frame_this_id,
 332   m68k_linux_sigtramp_frame_prev_register,
 333   NULL,
 334   m68k_linux_sigtramp_frame_sniffer
 335 };
 336
 337 static void
 338 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 339 {
 340   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 341
 342   linux_init_abi (info, 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_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
 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   set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type);
 376 }
 377
 378 /* Provide a prototype to silence -Wmissing-prototypes.  */
 379 extern initialize_file_ftype _initialize_m68k_linux_tdep;
 380
 381 void
 382 _initialize_m68k_linux_tdep (void)
 383 {
 384   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 385                           m68k_linux_init_abi);
 386   observer_attach_inferior_created (m68k_linux_inferior_created);
 387 }