gdb/m68k-linux-tdep.c

   1 /* Motorola m68k target-dependent support for GNU/Linux.
   2
   3    Copyright (C) 1996-2020 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 "frame.h"
  23 #include "target.h"
  24 #include "gdbtypes.h"
  25 #include "osabi.h"
  26 #include "regcache.h"
  27 #include "objfiles.h"
  28 #include "symtab.h"
  29 #include "m68k-tdep.h"
  30 #include "trad-frame.h"
  31 #include "frame-unwind.h"
  32 #include "glibc-tdep.h"
  33 #include "solib-svr4.h"
  34 #include "auxv.h"
  35 #include "observable.h"
  36 #include "elf/common.h"
  37 #include "linux-tdep.h"
  38 #include "regset.h"
  39 \f
  40 /* Offsets (in target ints) into jmp_buf.  */
  41
  42 #define M68K_LINUX_JB_ELEMENT_SIZE 4
  43 #define M68K_LINUX_JB_PC 7
  44
  45 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  46
  47 #define IS_SIGTRAMP(insn1, insn2)                                       \
  48   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  49    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  50    /* moveq #119,d0; trap #0 */                                         \
  51    || insn1 == 0x70774e40)
  52
  53 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  54   (/* movel #173,d0; trap #0 */                                         \
  55    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  56    /* moveq #82,d0; notb d0; trap #0 */                                 \
  57    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  58
  59 /* Return non-zero if THIS_FRAME corresponds to a signal trampoline.  For
  60    the sake of m68k_linux_get_sigtramp_info we also distinguish between
  61    non-RT and RT signal trampolines.  */
  62
  63 static int
  64 m68k_linux_pc_in_sigtramp (struct frame_info *this_frame)
  65 {
  66   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  67   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  68   gdb_byte buf[12];
  69   unsigned long insn0, insn1, insn2;
  70   CORE_ADDR pc = get_frame_pc (this_frame);
  71
  72   if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, sizeof (buf)))
  73     return 0;
  74   insn1 = extract_unsigned_integer (buf + 4, 4, byte_order);
  75   insn2 = extract_unsigned_integer (buf + 8, 4, byte_order);
  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, byte_order);
  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 *this_frame)
 223 {
 224   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 225   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 226   CORE_ADDR sp;
 227   struct m68k_linux_sigtramp_info info;
 228
 229   /* Determine whether we are running on a uClinux or normal GNU/Linux
 230      target so we can use the correct sigcontext layouts.  */
 231   if (target_is_uclinux == -1)
 232     target_is_uclinux = linux_is_uclinux ();
 233
 234   sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
 235
 236   /* Get sigcontext address, it is the third parameter on the stack.  */
 237   info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4, byte_order);
 238
 239   if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
 240     info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
 241   else
 242     info.sc_reg_offset = (target_is_uclinux
 243                           ? m68k_uclinux_sigcontext_reg_offset
 244                           : m68k_linux_sigcontext_reg_offset);
 245   return info;
 246 }
 247
 248 /* Signal trampolines.  */
 249
 250 static struct trad_frame_cache *
 251 m68k_linux_sigtramp_frame_cache (struct frame_info *this_frame,
 252                                  void **this_cache)
 253 {
 254   struct frame_id this_id;
 255   struct trad_frame_cache *cache;
 256   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 257   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 258   struct m68k_linux_sigtramp_info info;
 259   gdb_byte buf[4];
 260   int i;
 261
 262   if (*this_cache)
 263     return (struct trad_frame_cache *) *this_cache;
 264
 265   cache = trad_frame_cache_zalloc (this_frame);
 266
 267   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 268      The frame ID's code address should be the start-address of the
 269      signal trampoline and not the current PC within that
 270      trampoline.  */
 271   get_frame_register (this_frame, M68K_SP_REGNUM, buf);
 272   /* See the end of m68k_push_dummy_call.  */
 273   this_id = frame_id_build (extract_unsigned_integer (buf, 4, byte_order)
 274                             - 4 + 8, get_frame_pc (this_frame));
 275   trad_frame_set_id (cache, this_id);
 276
 277   info = m68k_linux_get_sigtramp_info (this_frame);
 278
 279   for (i = 0; i < M68K_NUM_REGS; i++)
 280     if (info.sc_reg_offset[i] != -1)
 281       trad_frame_set_reg_addr (cache, i,
 282                                info.sigcontext_addr + info.sc_reg_offset[i]);
 283
 284   *this_cache = cache;
 285   return cache;
 286 }
 287
 288 static void
 289 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 290                                    void **this_cache,
 291                                    struct frame_id *this_id)
 292 {
 293   struct trad_frame_cache *cache =
 294     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 295   trad_frame_get_id (cache, this_id);
 296 }
 297
 298 static struct value *
 299 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 300                                          void **this_cache,
 301                                          int regnum)
 302 {
 303   /* Make sure we've initialized the cache.  */
 304   struct trad_frame_cache *cache =
 305     m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
 306   return trad_frame_get_register (cache, this_frame, regnum);
 307 }
 308
 309 static int
 310 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 311                                    struct frame_info *this_frame,
 312                                    void **this_prologue_cache)
 313 {
 314   return m68k_linux_pc_in_sigtramp (this_frame);
 315 }
 316
 317 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
 318 {
 319   SIGTRAMP_FRAME,
 320   default_frame_unwind_stop_reason,
 321   m68k_linux_sigtramp_frame_this_id,
 322   m68k_linux_sigtramp_frame_prev_register,
 323   NULL,
 324   m68k_linux_sigtramp_frame_sniffer
 325 };
 326
 327 /* Register maps for supply/collect regset functions.  */
 328
 329 static const struct regcache_map_entry m68k_linux_gregmap[] =
 330   {
 331     { 7, M68K_D1_REGNUM, 4 },   /* d1 ... d7 */
 332     { 7, M68K_A0_REGNUM, 4 },   /* a0 ... a6 */
 333     { 1, M68K_D0_REGNUM, 4 },
 334     { 1, M68K_SP_REGNUM, 4 },
 335     { 1, REGCACHE_MAP_SKIP, 4 }, /* orig_d0 (skip) */
 336     { 1, M68K_PS_REGNUM, 4 },
 337     { 1, M68K_PC_REGNUM, 4 },
 338     /* Ignore 16-bit fields 'fmtvec' and '__fill'.  */
 339     { 0 }
 340   };
 341
 342 #define M68K_LINUX_GREGS_SIZE (20 * 4)
 343
 344 static const struct regcache_map_entry m68k_linux_fpregmap[] =
 345   {
 346     { 8, M68K_FP0_REGNUM, 12 }, /* fp0 ... fp7 */
 347     { 1, M68K_FPC_REGNUM, 4 },
 348     { 1, M68K_FPS_REGNUM, 4 },
 349     { 1, M68K_FPI_REGNUM, 4 },
 350     { 0 }
 351   };
 352
 353 #define M68K_LINUX_FPREGS_SIZE (27 * 4)
 354
 355 /* Register sets. */
 356
 357 static const struct regset m68k_linux_gregset =
 358   {
 359     m68k_linux_gregmap,
 360     regcache_supply_regset, regcache_collect_regset
 361   };
 362
 363 static const struct regset m68k_linux_fpregset =
 364   {
 365     m68k_linux_fpregmap,
 366     regcache_supply_regset, regcache_collect_regset
 367   };
 368
 369 /* Iterate over core file register note sections.  */
 370
 371 static void
 372 m68k_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
 373                                          iterate_over_regset_sections_cb *cb,
 374                                          void *cb_data,
 375                                          const struct regcache *regcache)
 376 {
 377   cb (".reg", M68K_LINUX_GREGS_SIZE, M68K_LINUX_GREGS_SIZE, &m68k_linux_gregset,
 378       NULL, cb_data);
 379   cb (".reg2", M68K_LINUX_FPREGS_SIZE, M68K_LINUX_FPREGS_SIZE,
 380       &m68k_linux_fpregset, NULL, cb_data);
 381 }
 382
 383 static void
 384 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 385 {
 386   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 387
 388   linux_init_abi (info, gdbarch);
 389
 390   tdep->jb_pc = M68K_LINUX_JB_PC;
 391   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 392
 393   /* GNU/Linux uses a calling convention that's similar to SVR4.  It
 394      returns integer values in %d0/%d1, pointer values in %a0 and
 395      floating values in %fp0, just like SVR4, but uses %a1 to pass the
 396      address to store a structure value.  It also returns small
 397      structures in registers instead of memory.  */
 398   m68k_svr4_init_abi (info, gdbarch);
 399   tdep->struct_value_regnum = M68K_A1_REGNUM;
 400   tdep->struct_return = reg_struct_return;
 401
 402   set_gdbarch_decr_pc_after_break (gdbarch, 2);
 403
 404   frame_unwind_append_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
 405
 406   /* Shared library handling.  */
 407
 408   /* GNU/Linux uses SVR4-style shared libraries.  */
 409   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 410                                          svr4_ilp32_fetch_link_map_offsets);
 411
 412   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 413   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 414
 415   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 416
 417   /* Core file support. */
 418   set_gdbarch_iterate_over_regset_sections
 419     (gdbarch, m68k_linux_iterate_over_regset_sections);
 420
 421   /* Enable TLS support.  */
 422   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 423                                              svr4_fetch_objfile_link_map);
 424 }
 425
 426 void _initialize_m68k_linux_tdep ();
 427 void
 428 _initialize_m68k_linux_tdep ()
 429 {
 430   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 431                           m68k_linux_init_abi);
 432   gdb::observers::inferior_created.attach (m68k_linux_inferior_created);
 433 }