gdb/i386-fbsd-tdep.c

   1 /* Target-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2003-2020 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 "arch-utils.h"
  22 #include "gdbcore.h"
  23 #include "osabi.h"
  24 #include "regcache.h"
  25 #include "regset.h"
  26 #include "i386-fbsd-tdep.h"
  27 #include "gdbsupport/x86-xstate.h"
  28
  29 #include "i386-tdep.h"
  30 #include "i387-tdep.h"
  31 #include "fbsd-tdep.h"
  32 #include "solib-svr4.h"
  33
  34 /* Support for signal handlers.  */
  35
  36 /* Return whether THIS_FRAME corresponds to a FreeBSD sigtramp
  37    routine.  */
  38
  39 /* FreeBSD/i386 supports three different signal trampolines, one for
  40    versions before 4.0, a second for 4.x, and a third for 5.0 and
  41    later.  To complicate matters, FreeBSD/i386 binaries running under
  42    an amd64 kernel use a different set of trampolines.  These
  43    trampolines differ from the i386 kernel trampolines in that they
  44    omit a middle section that conditionally restores %gs.  */
  45
  46 static const gdb_byte i386fbsd_sigtramp_start[] =
  47 {
  48   0x8d, 0x44, 0x24, 0x20,       /* lea     SIGF_UC(%esp),%eax */
  49   0x50                          /* pushl   %eax */
  50 };
  51
  52 static const gdb_byte i386fbsd_sigtramp_middle[] =
  53 {
  54   0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
  55                                 /* testl   $PSL_VM,UC_EFLAGS(%eax) */
  56   0x75, 0x03,                   /* jne     +3 */
  57   0x8e, 0x68, 0x14              /* mov     UC_GS(%eax),%gs */
  58 };
  59
  60 static const gdb_byte i386fbsd_sigtramp_end[] =
  61 {
  62   0xb8, 0xa1, 0x01, 0x00, 0x00, /* movl   $SYS_sigreturn,%eax */
  63   0x50,                 /* pushl   %eax */
  64   0xcd, 0x80                    /* int     $0x80 */
  65 };
  66
  67 static const gdb_byte i386fbsd_freebsd4_sigtramp_start[] =
  68 {
  69   0x8d, 0x44, 0x24, 0x14,       /* lea     SIGF_UC4(%esp),%eax */
  70   0x50                          /* pushl   %eax */
  71 };
  72
  73 static const gdb_byte i386fbsd_freebsd4_sigtramp_middle[] =
  74 {
  75   0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
  76                                 /* testl   $PSL_VM,UC4_EFLAGS(%eax) */
  77   0x75, 0x03,                   /* jne     +3 */
  78   0x8e, 0x68, 0x14              /* mov     UC4_GS(%eax),%gs */
  79 };
  80
  81 static const gdb_byte i386fbsd_freebsd4_sigtramp_end[] =
  82 {
  83   0xb8, 0x58, 0x01, 0x00, 0x00, /* movl    $344,%eax */
  84   0x50,                 /* pushl   %eax */
  85   0xcd, 0x80                    /* int     $0x80 */
  86 };
  87
  88 static const gdb_byte i386fbsd_osigtramp_start[] =
  89 {
  90   0x8d, 0x44, 0x24, 0x14,       /* lea     SIGF_SC(%esp),%eax */
  91   0x50                          /* pushl   %eax */
  92 };
  93
  94 static const gdb_byte i386fbsd_osigtramp_middle[] =
  95 {
  96   0xf7, 0x40, 0x18, 0x00, 0x00, 0x02, 0x00,
  97                                 /* testl   $PSL_VM,SC_PS(%eax) */
  98   0x75, 0x03,                   /* jne     +3 */
  99   0x8e, 0x68, 0x44              /* mov     SC_GS(%eax),%gs */
 100 };
 101
 102 static const gdb_byte i386fbsd_osigtramp_end[] =
 103 {
 104   0xb8, 0x67, 0x00, 0x00, 0x00, /* movl    $103,%eax */
 105   0x50,                 /* pushl   %eax */
 106   0xcd, 0x80                    /* int     $0x80 */
 107 };
 108
 109 /* The three different trampolines are all the same size.  */
 110 gdb_static_assert (sizeof i386fbsd_sigtramp_start
 111                    == sizeof i386fbsd_freebsd4_sigtramp_start);
 112 gdb_static_assert (sizeof i386fbsd_sigtramp_start
 113                    == sizeof i386fbsd_osigtramp_start);
 114 gdb_static_assert (sizeof i386fbsd_sigtramp_middle
 115                    == sizeof i386fbsd_freebsd4_sigtramp_middle);
 116 gdb_static_assert (sizeof i386fbsd_sigtramp_middle
 117                    == sizeof i386fbsd_osigtramp_middle);
 118 gdb_static_assert (sizeof i386fbsd_sigtramp_end
 119                    == sizeof i386fbsd_freebsd4_sigtramp_end);
 120 gdb_static_assert (sizeof i386fbsd_sigtramp_end
 121                    == sizeof i386fbsd_osigtramp_end);
 122
 123 /* We assume that the middle is the largest chunk below.  */
 124 gdb_static_assert (sizeof i386fbsd_sigtramp_middle
 125                    > sizeof i386fbsd_sigtramp_start);
 126 gdb_static_assert (sizeof i386fbsd_sigtramp_middle
 127                    > sizeof i386fbsd_sigtramp_end);
 128
 129 static int
 130 i386fbsd_sigtramp_p (struct frame_info *this_frame)
 131 {
 132   CORE_ADDR pc = get_frame_pc (this_frame);
 133   gdb_byte buf[sizeof i386fbsd_sigtramp_middle];
 134   const gdb_byte *middle, *end;
 135
 136   /* Look for a matching start.  */
 137   if (!safe_frame_unwind_memory (this_frame, pc, buf,
 138                                  sizeof i386fbsd_sigtramp_start))
 139     return 0;
 140   if (memcmp (buf, i386fbsd_sigtramp_start, sizeof i386fbsd_sigtramp_start)
 141       == 0)
 142     {
 143       middle = i386fbsd_sigtramp_middle;
 144       end = i386fbsd_sigtramp_end;
 145     }
 146   else if (memcmp (buf, i386fbsd_freebsd4_sigtramp_start,
 147                    sizeof i386fbsd_freebsd4_sigtramp_start) == 0)
 148     {
 149       middle = i386fbsd_freebsd4_sigtramp_middle;
 150       end = i386fbsd_freebsd4_sigtramp_end;
 151     }
 152   else if (memcmp (buf, i386fbsd_osigtramp_start,
 153                    sizeof i386fbsd_osigtramp_start) == 0)
 154     {
 155       middle = i386fbsd_osigtramp_middle;
 156       end = i386fbsd_osigtramp_end;
 157     }
 158   else
 159     return 0;
 160
 161   /* Since the end is shorter than the middle, check for a matching end
 162      next.  */
 163   pc += sizeof i386fbsd_sigtramp_start;
 164   if (!safe_frame_unwind_memory (this_frame, pc, buf,
 165                                  sizeof i386fbsd_sigtramp_end))
 166     return 0;
 167   if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) == 0)
 168     return 1;
 169
 170   /* If the end didn't match, check for a matching middle.  */
 171   if (!safe_frame_unwind_memory (this_frame, pc, buf,
 172                                  sizeof i386fbsd_sigtramp_middle))
 173     return 0;
 174   if (memcmp (buf, middle, sizeof i386fbsd_sigtramp_middle) != 0)
 175     return 0;
 176
 177   /* The middle matched, check for a matching end.  */
 178   pc += sizeof i386fbsd_sigtramp_middle;
 179   if (!safe_frame_unwind_memory (this_frame, pc, buf,
 180                                  sizeof i386fbsd_sigtramp_end))
 181     return 0;
 182   if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) != 0)
 183     return 0;
 184
 185   return 1;
 186 }
 187
 188 /* FreeBSD 3.0-RELEASE or later.  */
 189
 190 /* From <machine/reg.h>.  */
 191 static int i386fbsd_r_reg_offset[] =
 192 {
 193   9 * 4, 8 * 4, 7 * 4, 6 * 4,   /* %eax, %ecx, %edx, %ebx */
 194   15 * 4, 4 * 4,                /* %esp, %ebp */
 195   3 * 4, 2 * 4,                 /* %esi, %edi */
 196   12 * 4, 14 * 4,               /* %eip, %eflags */
 197   13 * 4, 16 * 4,               /* %cs, %ss */
 198   1 * 4, 0 * 4, -1, -1          /* %ds, %es, %fs, %gs */
 199 };
 200
 201 /* Sigtramp routine location.  */
 202 CORE_ADDR i386fbsd_sigtramp_start_addr;
 203 CORE_ADDR i386fbsd_sigtramp_end_addr;
 204
 205 /* From <machine/signal.h>.  */
 206 int i386fbsd_sc_reg_offset[] =
 207 {
 208   8 + 14 * 4,                   /* %eax */
 209   8 + 13 * 4,                   /* %ecx */
 210   8 + 12 * 4,                   /* %edx */
 211   8 + 11 * 4,                   /* %ebx */
 212   8 + 0 * 4,                    /* %esp */
 213   8 + 1 * 4,                    /* %ebp */
 214   8 + 10 * 4,                   /* %esi */
 215   8 + 9 * 4,                    /* %edi */
 216   8 + 3 * 4,                    /* %eip */
 217   8 + 4 * 4,                    /* %eflags */
 218   8 + 7 * 4,                    /* %cs */
 219   8 + 8 * 4,                    /* %ss */
 220   8 + 6 * 4,                    /* %ds */
 221   8 + 5 * 4,                    /* %es */
 222   8 + 15 * 4,                   /* %fs */
 223   8 + 16 * 4                    /* %gs */
 224 };
 225
 226 /* Get XSAVE extended state xcr0 from core dump.  */
 227
 228 uint64_t
 229 i386fbsd_core_read_xcr0 (bfd *abfd)
 230 {
 231   asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
 232   uint64_t xcr0;
 233
 234   if (xstate)
 235     {
 236       size_t size = bfd_section_size (xstate);
 237
 238       /* Check extended state size.  */
 239       if (size < X86_XSTATE_AVX_SIZE)
 240         xcr0 = X86_XSTATE_SSE_MASK;
 241       else
 242         {
 243           char contents[8];
 244
 245           if (! bfd_get_section_contents (abfd, xstate, contents,
 246                                           I386_FBSD_XSAVE_XCR0_OFFSET,
 247                                           8))
 248             {
 249               warning (_("Couldn't read `xcr0' bytes from "
 250                          "`.reg-xstate' section in core file."));
 251               return X86_XSTATE_SSE_MASK;
 252             }
 253
 254           xcr0 = bfd_get_64 (abfd, contents);
 255         }
 256     }
 257   else
 258     xcr0 = X86_XSTATE_SSE_MASK;
 259
 260   return xcr0;
 261 }
 262
 263 /* Implement the core_read_description gdbarch method.  */
 264
 265 static const struct target_desc *
 266 i386fbsd_core_read_description (struct gdbarch *gdbarch,
 267                                 struct target_ops *target,
 268                                 bfd *abfd)
 269 {
 270   return i386_target_description (i386fbsd_core_read_xcr0 (abfd), true);
 271 }
 272
 273 /* Similar to i386_supply_fpregset, but use XSAVE extended state.  */
 274
 275 static void
 276 i386fbsd_supply_xstateregset (const struct regset *regset,
 277                               struct regcache *regcache, int regnum,
 278                               const void *xstateregs, size_t len)
 279 {
 280   i387_supply_xsave (regcache, regnum, xstateregs);
 281 }
 282
 283 /* Similar to i386_collect_fpregset, but use XSAVE extended state.  */
 284
 285 static void
 286 i386fbsd_collect_xstateregset (const struct regset *regset,
 287                                const struct regcache *regcache,
 288                                int regnum, void *xstateregs, size_t len)
 289 {
 290   i387_collect_xsave (regcache, regnum, xstateregs, 1);
 291 }
 292
 293 /* Register set definitions.  */
 294
 295 static const struct regset i386fbsd_xstateregset =
 296   {
 297     NULL,
 298     i386fbsd_supply_xstateregset,
 299     i386fbsd_collect_xstateregset
 300   };
 301
 302 /* Iterate over core file register note sections.  */
 303
 304 static void
 305 i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 306                                        iterate_over_regset_sections_cb *cb,
 307                                        void *cb_data,
 308                                        const struct regcache *regcache)
 309 {
 310   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 311
 312   cb (".reg", tdep->sizeof_gregset, tdep->sizeof_gregset, &i386_gregset, NULL,
 313       cb_data);
 314   cb (".reg2", tdep->sizeof_fpregset, tdep->sizeof_fpregset, &i386_fpregset,
 315       NULL, cb_data);
 316
 317   if (tdep->xcr0 & X86_XSTATE_AVX)
 318     cb (".reg-xstate", X86_XSTATE_SIZE (tdep->xcr0),
 319         X86_XSTATE_SIZE (tdep->xcr0), &i386fbsd_xstateregset,
 320         "XSAVE extended state", cb_data);
 321 }
 322
 323 /* Implement the get_thread_local_address gdbarch method.  */
 324
 325 static CORE_ADDR
 326 i386fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
 327                                    CORE_ADDR lm_addr, CORE_ADDR offset)
 328 {
 329   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 330   struct regcache *regcache;
 331
 332   if (tdep->fsbase_regnum == -1)
 333     error (_("Unable to fetch %%gsbase"));
 334
 335   regcache = get_thread_arch_regcache (ptid, gdbarch);
 336
 337   target_fetch_registers (regcache, tdep->fsbase_regnum + 1);
 338
 339   ULONGEST gsbase;
 340   if (regcache->cooked_read (tdep->fsbase_regnum + 1, &gsbase) != REG_VALID)
 341     error (_("Unable to fetch %%gsbase"));
 342
 343   CORE_ADDR dtv_addr = gsbase + gdbarch_ptr_bit (gdbarch) / 8;
 344   return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
 345 }
 346
 347 static void
 348 i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 349 {
 350   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 351
 352   /* Obviously FreeBSD is BSD-based.  */
 353   i386bsd_init_abi (info, gdbarch);
 354
 355   /* FreeBSD has a different `struct reg', and reserves some space for
 356      its FPU emulator in `struct fpreg'.  */
 357   tdep->gregset_reg_offset = i386fbsd_r_reg_offset;
 358   tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd_r_reg_offset);
 359   tdep->sizeof_gregset = 18 * 4;
 360   tdep->sizeof_fpregset = 176;
 361
 362   /* FreeBSD uses -freg-struct-return by default.  */
 363   tdep->struct_return = reg_struct_return;
 364
 365   tdep->sigtramp_p = i386fbsd_sigtramp_p;
 366
 367   /* FreeBSD uses a different memory layout.  */
 368   tdep->sigtramp_start = i386fbsd_sigtramp_start_addr;
 369   tdep->sigtramp_end = i386fbsd_sigtramp_end_addr;
 370
 371   /* FreeBSD has a more complete `struct sigcontext'.  */
 372   tdep->sc_reg_offset = i386fbsd_sc_reg_offset;
 373   tdep->sc_num_regs = ARRAY_SIZE (i386fbsd_sc_reg_offset);
 374
 375   i386_elf_init_abi (info, gdbarch);
 376
 377   /* FreeBSD uses SVR4-style shared libraries.  */
 378   set_solib_svr4_fetch_link_map_offsets
 379     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 380 }
 381
 382 /* FreeBSD 4.0-RELEASE or later.  */
 383
 384 /* From <machine/reg.h>.  */
 385 static int i386fbsd4_r_reg_offset[] =
 386 {
 387   10 * 4, 9 * 4, 8 * 4, 7 * 4,  /* %eax, %ecx, %edx, %ebx */
 388   16 * 4, 5 * 4,                /* %esp, %ebp */
 389   4 * 4, 3 * 4,                 /* %esi, %edi */
 390   13 * 4, 15 * 4,               /* %eip, %eflags */
 391   14 * 4, 17 * 4,               /* %cs, %ss */
 392   2 * 4, 1 * 4, 0 * 4, 18 * 4   /* %ds, %es, %fs, %gs */
 393 };
 394
 395 /* From <machine/signal.h>.  */
 396 int i386fbsd4_sc_reg_offset[] =
 397 {
 398   20 + 11 * 4,                  /* %eax */
 399   20 + 10 * 4,                  /* %ecx */
 400   20 + 9 * 4,                   /* %edx */
 401   20 + 8 * 4,                   /* %ebx */
 402   20 + 17 * 4,                  /* %esp */
 403   20 + 6 * 4,                   /* %ebp */
 404   20 + 5 * 4,                   /* %esi */
 405   20 + 4 * 4,                   /* %edi */
 406   20 + 14 * 4,                  /* %eip */
 407   20 + 16 * 4,                  /* %eflags */
 408   20 + 15 * 4,                  /* %cs */
 409   20 + 18 * 4,                  /* %ss */
 410   20 + 3 * 4,                   /* %ds */
 411   20 + 2 * 4,                   /* %es */
 412   20 + 1 * 4,                   /* %fs */
 413   20 + 0 * 4                    /* %gs */
 414 };
 415
 416 static void
 417 i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 418 {
 419   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 420
 421   /* Generic FreeBSD support. */
 422   fbsd_init_abi (info, gdbarch);
 423
 424   /* Inherit stuff from older releases.  We assume that FreeBSD
 425      4.0-RELEASE always uses ELF.  */
 426   i386fbsd_init_abi (info, gdbarch);
 427
 428   /* FreeBSD 4.0 introduced a new `struct reg'.  */
 429   tdep->gregset_reg_offset = i386fbsd4_r_reg_offset;
 430   tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd4_r_reg_offset);
 431   tdep->sizeof_gregset = 19 * 4;
 432
 433   /* FreeBSD 4.0 introduced a new `struct sigcontext'.  */
 434   tdep->sc_reg_offset = i386fbsd4_sc_reg_offset;
 435   tdep->sc_num_regs = ARRAY_SIZE (i386fbsd4_sc_reg_offset);
 436
 437   tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
 438
 439   /* Iterate over core file register note sections.  */
 440   set_gdbarch_iterate_over_regset_sections
 441     (gdbarch, i386fbsd_iterate_over_regset_sections);
 442
 443   set_gdbarch_core_read_description (gdbarch,
 444                                      i386fbsd_core_read_description);
 445
 446   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 447                                              svr4_fetch_objfile_link_map);
 448   set_gdbarch_get_thread_local_address (gdbarch,
 449                                         i386fbsd_get_thread_local_address);
 450 }
 451
 452 void
 453 _initialize_i386fbsd_tdep (void)
 454 {
 455   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
 456                           i386fbsd4_init_abi);
 457 }