gdb/i386-fbsd-tdep.c

   1 /* Target-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2003-2024 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 "gdbcore.h"
  21 #include "osabi.h"
  22 #include "regcache.h"
  23 #include "regset.h"
  24 #include "trad-frame.h"
  25 #include "tramp-frame.h"
  26 #include "i386-fbsd-tdep.h"
  27
  28 #include "i386-tdep.h"
  29 #include "i387-tdep.h"
  30 #include "fbsd-tdep.h"
  31 #include "solib-svr4.h"
  32 #include "inferior.h"
  33
  34 /* The general-purpose regset consists of 19 32-bit slots.  */
  35 #define I386_FBSD_SIZEOF_GREGSET        (19 * 4)
  36
  37 /* The segment base register set consists of 2 32-bit registers.  */
  38 #define I386_FBSD_SIZEOF_SEGBASES_REGSET        (2 * 4)
  39
  40 /* Register maps.  */
  41
  42 static const struct regcache_map_entry i386_fbsd_gregmap[] =
  43 {
  44   { 1, I386_FS_REGNUM, 4 },
  45   { 1, I386_ES_REGNUM, 4 },
  46   { 1, I386_DS_REGNUM, 4 },
  47   { 1, I386_EDI_REGNUM, 0 },
  48   { 1, I386_ESI_REGNUM, 0 },
  49   { 1, I386_EBP_REGNUM, 0 },
  50   { 1, REGCACHE_MAP_SKIP, 4 },  /* isp */
  51   { 1, I386_EBX_REGNUM, 0 },
  52   { 1, I386_EDX_REGNUM, 0 },
  53   { 1, I386_ECX_REGNUM, 0 },
  54   { 1, I386_EAX_REGNUM, 0 },
  55   { 1, REGCACHE_MAP_SKIP, 4 },  /* trapno */
  56   { 1, REGCACHE_MAP_SKIP, 4 },  /* err */
  57   { 1, I386_EIP_REGNUM, 0 },
  58   { 1, I386_CS_REGNUM, 4 },
  59   { 1, I386_EFLAGS_REGNUM, 0 },
  60   { 1, I386_ESP_REGNUM, 0 },
  61   { 1, I386_SS_REGNUM, 4 },
  62   { 1, I386_GS_REGNUM, 4 },
  63   { 0 }
  64 };
  65
  66 static const struct regcache_map_entry i386_fbsd_segbases_regmap[] =
  67 {
  68   { 1, I386_FSBASE_REGNUM, 0 },
  69   { 1, I386_GSBASE_REGNUM, 0 },
  70   { 0 }
  71 };
  72
  73 /* This layout including fsbase and gsbase was adopted in FreeBSD
  74    8.0.  */
  75
  76 static const struct regcache_map_entry i386_fbsd_mcregmap[] =
  77 {
  78   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_onstack */
  79   { 1, I386_GS_REGNUM, 4 },
  80   { 1, I386_FS_REGNUM, 4 },
  81   { 1, I386_ES_REGNUM, 4 },
  82   { 1, I386_DS_REGNUM, 4 },
  83   { 1, I386_EDI_REGNUM, 0 },
  84   { 1, I386_ESI_REGNUM, 0 },
  85   { 1, I386_EBP_REGNUM, 0 },
  86   { 1, REGCACHE_MAP_SKIP, 4 },  /* isp */
  87   { 1, I386_EBX_REGNUM, 0 },
  88   { 1, I386_EDX_REGNUM, 0 },
  89   { 1, I386_ECX_REGNUM, 0 },
  90   { 1, I386_EAX_REGNUM, 0 },
  91   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_trapno */
  92   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_err */
  93   { 1, I386_EIP_REGNUM, 0 },
  94   { 1, I386_CS_REGNUM, 4 },
  95   { 1, I386_EFLAGS_REGNUM, 0 },
  96   { 1, I386_ESP_REGNUM, 0 },
  97   { 1, I386_SS_REGNUM, 4 },
  98   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_len */
  99   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_fpformat */
 100   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_ownedfp */
 101   { 1, REGCACHE_MAP_SKIP, 4 },  /* mc_flags */
 102   { 128, REGCACHE_MAP_SKIP, 4 },/* mc_fpstate */
 103   { 1, I386_FSBASE_REGNUM, 0 },
 104   { 1, I386_GSBASE_REGNUM, 0 },
 105   { 0 }
 106 };
 107
 108 /* Register set definitions.  */
 109
 110 const struct regset i386_fbsd_gregset =
 111 {
 112   i386_fbsd_gregmap, regcache_supply_regset, regcache_collect_regset
 113 };
 114
 115 const struct regset i386_fbsd_segbases_regset =
 116 {
 117   i386_fbsd_segbases_regmap, regcache_supply_regset, regcache_collect_regset
 118 };
 119
 120 /* Support for signal handlers.  */
 121
 122 /* In a signal frame, esp points to a 'struct sigframe' which is
 123    defined as:
 124
 125    struct sigframe {
 126         register_t      sf_signum;
 127         register_t      sf_siginfo;
 128         register_t      sf_ucontext;
 129         register_t      sf_addr;
 130         union {
 131                 __siginfohandler_t      *sf_action;
 132                 __sighandler_t          *sf_handler;
 133         } sf_ahu;
 134         ucontext_t      sf_uc;
 135         ...
 136    }
 137
 138    ucontext_t is defined as:
 139
 140    struct __ucontext {
 141            sigset_t     uc_sigmask;
 142            mcontext_t   uc_mcontext;
 143            ...
 144    };
 145
 146    The mcontext_t contains the general purpose register set as well
 147    as the floating point or XSAVE state.  */
 148
 149 /* NB: There is a 12 byte padding hole between sf_ahu and sf_uc. */
 150 #define I386_SIGFRAME_UCONTEXT_OFFSET           32
 151 #define I386_UCONTEXT_MCONTEXT_OFFSET           16
 152 #define I386_SIZEOF_MCONTEXT_T                  640
 153
 154 /* Implement the "init" method of struct tramp_frame.  */
 155
 156 static void
 157 i386_fbsd_sigframe_init (const struct tramp_frame *self,
 158                          const frame_info_ptr &this_frame,
 159                          struct trad_frame_cache *this_cache,
 160                          CORE_ADDR func)
 161 {
 162   CORE_ADDR sp = get_frame_register_unsigned (this_frame, I386_ESP_REGNUM);
 163   CORE_ADDR mcontext_addr
 164     = (sp
 165        + I386_SIGFRAME_UCONTEXT_OFFSET
 166        + I386_UCONTEXT_MCONTEXT_OFFSET);
 167
 168   trad_frame_set_reg_regmap (this_cache, i386_fbsd_mcregmap, mcontext_addr,
 169                              I386_SIZEOF_MCONTEXT_T);
 170
 171   /* Don't bother with floating point or XSAVE state for now.  The
 172      current helper routines for parsing FXSAVE and XSAVE state only
 173      work with regcaches.  This could perhaps create a temporary
 174      regcache, collect the register values from mc_fpstate and
 175      mc_xfpustate, and then set register values in the trad_frame.  */
 176
 177   trad_frame_set_id (this_cache, frame_id_build (sp, func));
 178 }
 179
 180 static const struct tramp_frame i386_fbsd_sigframe =
 181 {
 182   SIGTRAMP_FRAME,
 183   1,
 184   {
 185     {0x8d, ULONGEST_MAX},               /* lea     SIGF_UC(%esp),%eax */
 186     {0x44, ULONGEST_MAX},
 187     {0x24, ULONGEST_MAX},
 188     {0x20, ULONGEST_MAX},
 189     {0x50, ULONGEST_MAX},               /* pushl   %eax */
 190     {0xf7, ULONGEST_MAX},               /* testl   $PSL_VM,UC_EFLAGS(%eax) */
 191     {0x40, ULONGEST_MAX},
 192     {0x54, ULONGEST_MAX},
 193     {0x00, ULONGEST_MAX},
 194     {0x00, ULONGEST_MAX},
 195     {0x02, ULONGEST_MAX},
 196     {0x00, ULONGEST_MAX},
 197     {0x75, ULONGEST_MAX},               /* jne     +3 */
 198     {0x03, ULONGEST_MAX},
 199     {0x8e, ULONGEST_MAX},               /* mov     UC_GS(%eax),%gs */
 200     {0x68, ULONGEST_MAX},
 201     {0x14, ULONGEST_MAX},
 202     {0xb8, ULONGEST_MAX},               /* movl   $SYS_sigreturn,%eax */
 203     {0xa1, ULONGEST_MAX},
 204     {0x01, ULONGEST_MAX},
 205     {0x00, ULONGEST_MAX},
 206     {0x00, ULONGEST_MAX},
 207     {0x50, ULONGEST_MAX},               /* pushl   %eax */
 208     {0xcd, ULONGEST_MAX},               /* int     $0x80 */
 209     {0x80, ULONGEST_MAX},
 210     {TRAMP_SENTINEL_INSN, ULONGEST_MAX}
 211   },
 212   i386_fbsd_sigframe_init
 213 };
 214
 215 /* FreeBSD/i386 binaries running under an amd64 kernel use a different
 216    trampoline.  This trampoline differs from the i386 kernel trampoline
 217    in that it omits a middle section that conditionally restores
 218    %gs.  */
 219
 220 static const struct tramp_frame i386_fbsd64_sigframe =
 221 {
 222   SIGTRAMP_FRAME,
 223   1,
 224   {
 225     {0x8d, ULONGEST_MAX},               /* lea     SIGF_UC(%esp),%eax */
 226     {0x44, ULONGEST_MAX},
 227     {0x24, ULONGEST_MAX},
 228     {0x20, ULONGEST_MAX},
 229     {0x50, ULONGEST_MAX},               /* pushl   %eax */
 230     {0xb8, ULONGEST_MAX},               /* movl   $SYS_sigreturn,%eax */
 231     {0xa1, ULONGEST_MAX},
 232     {0x01, ULONGEST_MAX},
 233     {0x00, ULONGEST_MAX},
 234     {0x00, ULONGEST_MAX},
 235     {0x50, ULONGEST_MAX},               /* pushl   %eax */
 236     {0xcd, ULONGEST_MAX},               /* int     $0x80 */
 237     {0x80, ULONGEST_MAX},
 238     {TRAMP_SENTINEL_INSN, ULONGEST_MAX}
 239   },
 240   i386_fbsd_sigframe_init
 241 };
 242
 243 /* See i386-fbsd-tdep.h.  */
 244
 245 uint64_t
 246 i386_fbsd_core_read_xsave_info (bfd *abfd, x86_xsave_layout &layout)
 247 {
 248   asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
 249   if (xstate == nullptr)
 250     return 0;
 251
 252   /* Check extended state size.  */
 253   size_t size = bfd_section_size (xstate);
 254   if (size < X86_XSTATE_AVX_SIZE)
 255     return 0;
 256
 257   char contents[8];
 258   if (! bfd_get_section_contents (abfd, xstate, contents,
 259                                   I386_FBSD_XSAVE_XCR0_OFFSET, 8))
 260     {
 261       warning (_("Couldn't read `xcr0' bytes from "
 262                  "`.reg-xstate' section in core file."));
 263       return 0;
 264     }
 265
 266   uint64_t xcr0 = bfd_get_64 (abfd, contents);
 267
 268   if (!i387_guess_xsave_layout (xcr0, size, layout))
 269     return 0;
 270
 271   return xcr0;
 272 }
 273
 274 /* See i386-fbsd-tdep.h.  */
 275
 276 bool
 277 i386_fbsd_core_read_x86_xsave_layout (struct gdbarch *gdbarch,
 278                                       x86_xsave_layout &layout)
 279 {
 280   return i386_fbsd_core_read_xsave_info (current_program_space->core_bfd (),
 281                                          layout) != 0;
 282 }
 283
 284 /* Implement the core_read_description gdbarch method.  */
 285
 286 static const struct target_desc *
 287 i386fbsd_core_read_description (struct gdbarch *gdbarch,
 288                                 struct target_ops *target,
 289                                 bfd *abfd)
 290 {
 291   x86_xsave_layout layout;
 292   uint64_t xcr0 = i386_fbsd_core_read_xsave_info (abfd, layout);
 293   if (xcr0 == 0)
 294     xcr0 = X86_XSTATE_X87_MASK;
 295   return i386_target_description (xcr0, true);
 296 }
 297
 298 /* Similar to i386_supply_fpregset, but use XSAVE extended state.  */
 299
 300 static void
 301 i386fbsd_supply_xstateregset (const struct regset *regset,
 302                               struct regcache *regcache, int regnum,
 303                               const void *xstateregs, size_t len)
 304 {
 305   i387_supply_xsave (regcache, regnum, xstateregs);
 306 }
 307
 308 /* Similar to i386_collect_fpregset, but use XSAVE extended state.  */
 309
 310 static void
 311 i386fbsd_collect_xstateregset (const struct regset *regset,
 312                                const struct regcache *regcache,
 313                                int regnum, void *xstateregs, size_t len)
 314 {
 315   i387_collect_xsave (regcache, regnum, xstateregs, 1);
 316 }
 317
 318 /* Register set definitions.  */
 319
 320 static const struct regset i386fbsd_xstateregset =
 321   {
 322     NULL,
 323     i386fbsd_supply_xstateregset,
 324     i386fbsd_collect_xstateregset
 325   };
 326
 327 /* Iterate over core file register note sections.  */
 328
 329 static void
 330 i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
 331                                        iterate_over_regset_sections_cb *cb,
 332                                        void *cb_data,
 333                                        const struct regcache *regcache)
 334 {
 335   i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
 336
 337   cb (".reg", I386_FBSD_SIZEOF_GREGSET, I386_FBSD_SIZEOF_GREGSET,
 338       &i386_fbsd_gregset, NULL, cb_data);
 339   cb (".reg2", tdep->sizeof_fpregset, tdep->sizeof_fpregset, &i386_fpregset,
 340       NULL, cb_data);
 341   cb (".reg-x86-segbases", I386_FBSD_SIZEOF_SEGBASES_REGSET,
 342       I386_FBSD_SIZEOF_SEGBASES_REGSET, &i386_fbsd_segbases_regset,
 343       "segment bases", cb_data);
 344
 345   if (tdep->xsave_layout.sizeof_xsave != 0)
 346     cb (".reg-xstate", tdep->xsave_layout.sizeof_xsave,
 347         tdep->xsave_layout.sizeof_xsave, &i386fbsd_xstateregset,
 348         "XSAVE extended state", cb_data);
 349 }
 350
 351 /* Implement the get_thread_local_address gdbarch method.  */
 352
 353 static CORE_ADDR
 354 i386fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
 355                                    CORE_ADDR lm_addr, CORE_ADDR offset)
 356 {
 357   regcache *regcache
 358     = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
 359
 360   target_fetch_registers (regcache, I386_GSBASE_REGNUM);
 361
 362   ULONGEST gsbase;
 363   if (regcache->cooked_read (I386_GSBASE_REGNUM, &gsbase) != REG_VALID)
 364     error (_("Unable to fetch %%gsbase"));
 365
 366   CORE_ADDR dtv_addr = gsbase + gdbarch_ptr_bit (gdbarch) / 8;
 367   return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
 368 }
 369
 370 static void
 371 i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 372 {
 373   i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
 374
 375   /* Generic FreeBSD support. */
 376   fbsd_init_abi (info, gdbarch);
 377
 378   /* Obviously FreeBSD is BSD-based.  */
 379   i386bsd_init_abi (info, gdbarch);
 380
 381   /* FreeBSD reserves some space for its FPU emulator in
 382      `struct fpreg'.  */
 383   tdep->sizeof_fpregset = 176;
 384
 385   /* FreeBSD uses -freg-struct-return by default.  */
 386   tdep->struct_return = reg_struct_return;
 387
 388   tramp_frame_prepend_unwinder (gdbarch, &i386_fbsd_sigframe);
 389   tramp_frame_prepend_unwinder (gdbarch, &i386_fbsd64_sigframe);
 390
 391   i386_elf_init_abi (info, gdbarch);
 392
 393   tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
 394   set_gdbarch_core_read_x86_xsave_layout
 395     (gdbarch, i386_fbsd_core_read_x86_xsave_layout);
 396
 397   /* Iterate over core file register note sections.  */
 398   set_gdbarch_iterate_over_regset_sections
 399     (gdbarch, i386fbsd_iterate_over_regset_sections);
 400
 401   set_gdbarch_core_read_description (gdbarch,
 402                                      i386fbsd_core_read_description);
 403
 404   /* FreeBSD uses SVR4-style shared libraries.  */
 405   set_solib_svr4_fetch_link_map_offsets
 406     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 407
 408   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 409                                              svr4_fetch_objfile_link_map);
 410   set_gdbarch_get_thread_local_address (gdbarch,
 411                                         i386fbsd_get_thread_local_address);
 412 }
 413
 414 void _initialize_i386fbsd_tdep ();
 415 void
 416 _initialize_i386fbsd_tdep ()
 417 {
 418   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
 419                           i386fbsd_init_abi);
 420 }