gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003, 2004, 2005, 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 "frame.h"
  23 #include "frame-unwind.h"
  24 #include "gdbcore.h"
  25 #include "symtab.h"
  26 #include "objfiles.h"
  27 #include "osabi.h"
  28 #include "regcache.h"
  29 #include "regset.h"
  30 #include "target.h"
  31 #include "trad-frame.h"
  32
  33 #include "gdb_assert.h"
  34 #include "gdb_string.h"
  35
  36 #include "amd64-tdep.h"
  37 #include "i387-tdep.h"
  38 #include "solib-svr4.h"
  39 #include "bsd-uthread.h"
  40
  41 /* Support for core dumps.  */
  42
  43 static void
  44 amd64obsd_supply_regset (const struct regset *regset,
  45                          struct regcache *regcache, int regnum,
  46                          const void *regs, size_t len)
  47 {
  48   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  49
  50   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  51
  52   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  53   amd64_supply_fxsave (regcache, regnum,
  54                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  55 }
  56
  57 static const struct regset *
  58 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  59                                     const char *sect_name, size_t sect_size)
  60 {
  61   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  62
  63   /* OpenBSD core dumps don't use seperate register sets for the
  64      general-purpose and floating-point registers.  */
  65
  66   if (strcmp (sect_name, ".reg") == 0
  67       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  68     {
  69       if (tdep->gregset == NULL)
  70         tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);
  71       return tdep->gregset;
  72     }
  73
  74   return NULL;
  75 }
  76 \f
  77
  78 /* Support for signal handlers.  */
  79
  80 /* Default page size.  */
  81 static const int amd64obsd_page_size = 4096;
  82
  83 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  84    routine.  */
  85
  86 static int
  87 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  88 {
  89   CORE_ADDR pc = get_frame_pc (this_frame);
  90   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  91   const gdb_byte sigreturn[] =
  92   {
  93     0x48, 0xc7, 0xc0,
  94     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  95     0xcd, 0x80                  /* int $0x80 */
  96   };
  97   size_t buflen = (sizeof sigreturn) + 1;
  98   gdb_byte *buf;
  99   char *name;
 100
 101   /* If the function has a valid symbol name, it isn't a
 102      trampoline.  */
 103   find_pc_partial_function (pc, &name, NULL, NULL);
 104   if (name != NULL)
 105     return 0;
 106
 107   /* If the function lives in a valid section (even without a starting
 108      point) it isn't a trampoline.  */
 109   if (find_pc_section (pc) != NULL)
 110     return 0;
 111
 112   /* If we can't read the instructions at START_PC, return zero.  */
 113   buf = alloca ((sizeof sigreturn) + 1);
 114   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 115     return 0;
 116
 117   /* Check for sigreturn(2).  Depending on how the assembler encoded
 118      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 119      7.  */
 120   if (memcmp (buf, sigreturn, sizeof sigreturn)
 121       && memcpy (buf + 1, sigreturn, sizeof sigreturn))
 122     return 0;
 123
 124   return 1;
 125 }
 126
 127 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 128    address of the associated sigcontext structure.  */
 129
 130 static CORE_ADDR
 131 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 132 {
 133   CORE_ADDR pc = get_frame_pc (this_frame);
 134   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 135
 136   /* The %rsp register points at `struct sigcontext' upon entry of a
 137      signal trampoline.  The relevant part of the trampoline is
 138
 139         call    *%rax
 140         movq    %rsp, %rdi
 141         pushq   %rdi
 142         movq    $SYS_sigreturn,%rax
 143         int     $0x80
 144
 145      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 146      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 147
 148   if (offset > 5)
 149     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 150   else
 151     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 152 }
 153 \f
 154 /* OpenBSD 3.5 or later.  */
 155
 156 /* Mapping between the general-purpose registers in `struct reg'
 157    format and GDB's register cache layout.  */
 158
 159 /* From <machine/reg.h>.  */
 160 int amd64obsd_r_reg_offset[] =
 161 {
 162   14 * 8,                       /* %rax */
 163   13 * 8,                       /* %rbx */
 164   3 * 8,                        /* %rcx */
 165   2 * 8,                        /* %rdx */
 166   1 * 8,                        /* %rsi */
 167   0 * 8,                        /* %rdi */
 168   12 * 8,                       /* %rbp */
 169   15 * 8,                       /* %rsp */
 170   4 * 8,                        /* %r8 .. */
 171   5 * 8,
 172   6 * 8,
 173   7 * 8,
 174   8 * 8,
 175   9 * 8,
 176   10 * 8,
 177   11 * 8,                       /* ... %r15 */
 178   16 * 8,                       /* %rip */
 179   17 * 8,                       /* %eflags */
 180   18 * 8,                       /* %cs */
 181   19 * 8,                       /* %ss */
 182   20 * 8,                       /* %ds */
 183   21 * 8,                       /* %es */
 184   22 * 8,                       /* %fs */
 185   23 * 8                        /* %gs */
 186 };
 187
 188 /* From <machine/signal.h>.  */
 189 static int amd64obsd_sc_reg_offset[] =
 190 {
 191   14 * 8,                       /* %rax */
 192   13 * 8,                       /* %rbx */
 193   3 * 8,                        /* %rcx */
 194   2 * 8,                        /* %rdx */
 195   1 * 8,                        /* %rsi */
 196   0 * 8,                        /* %rdi */
 197   12 * 8,                       /* %rbp */
 198   24 * 8,                       /* %rsp */
 199   4 * 8,                        /* %r8 ... */
 200   5 * 8,
 201   6 * 8,
 202   7 * 8,
 203   8 * 8,
 204   9 * 8,
 205   10 * 8,
 206   11 * 8,                       /* ... %r15 */
 207   21 * 8,                       /* %rip */
 208   23 * 8,                       /* %eflags */
 209   22 * 8,                       /* %cs */
 210   25 * 8,                       /* %ss */
 211   18 * 8,                       /* %ds */
 212   17 * 8,                       /* %es */
 213   16 * 8,                       /* %fs */
 214   15 * 8                        /* %gs */
 215 };
 216
 217 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 218 static int amd64obsd_uthread_reg_offset[] =
 219 {
 220   19 * 8,                       /* %rax */
 221   16 * 8,                       /* %rbx */
 222   18 * 8,                       /* %rcx */
 223   17 * 8,                       /* %rdx */
 224   14 * 8,                       /* %rsi */
 225   13 * 8,                       /* %rdi */
 226   15 * 8,                       /* %rbp */
 227   -1,                           /* %rsp */
 228   12 * 8,                       /* %r8 ... */
 229   11 * 8,
 230   10 * 8,
 231   9 * 8,
 232   8 * 8,
 233   7 * 8,
 234   6 * 8,
 235   5 * 8,                        /* ... %r15 */
 236   20 * 8,                       /* %rip */
 237   4 * 8,                        /* %eflags */
 238   21 * 8,                       /* %cs */
 239   -1,                           /* %ss */
 240   3 * 8,                        /* %ds */
 241   2 * 8,                        /* %es */
 242   1 * 8,                        /* %fs */
 243   0 * 8                         /* %gs */
 244 };
 245
 246 /* Offset within the thread structure where we can find the saved
 247    stack pointer (%esp).  */
 248 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 249
 250 static void
 251 amd64obsd_supply_uthread (struct regcache *regcache,
 252                           int regnum, CORE_ADDR addr)
 253 {
 254   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 255   CORE_ADDR sp = 0;
 256   gdb_byte buf[8];
 257   int i;
 258
 259   gdb_assert (regnum >= -1);
 260
 261   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 262     {
 263       int offset;
 264
 265       /* Fetch stack pointer from thread structure.  */
 266       sp = read_memory_unsigned_integer (sp_addr, 8);
 267
 268       /* Adjust the stack pointer such that it looks as if we just
 269          returned from _thread_machdep_switch.  */
 270       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 271       store_unsigned_integer (buf, 8, sp + offset);
 272       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 273     }
 274
 275   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 276     {
 277       if (amd64obsd_uthread_reg_offset[i] != -1
 278           && (regnum == -1 || regnum == i))
 279         {
 280           /* Fetch stack pointer from thread structure (if we didn't
 281              do so already).  */
 282           if (sp == 0)
 283             sp = read_memory_unsigned_integer (sp_addr, 8);
 284
 285           /* Read the saved register from the stack frame.  */
 286           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 287           regcache_raw_supply (regcache, i, buf);
 288         }
 289     }
 290 }
 291
 292 static void
 293 amd64obsd_collect_uthread (const struct regcache *regcache,
 294                            int regnum, CORE_ADDR addr)
 295 {
 296   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 297   CORE_ADDR sp = 0;
 298   gdb_byte buf[8];
 299   int i;
 300
 301   gdb_assert (regnum >= -1);
 302
 303   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 304     {
 305       int offset;
 306
 307       /* Calculate the stack pointer (frame pointer) that will be
 308          stored into the thread structure.  */
 309       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 310       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 311       sp = extract_unsigned_integer (buf, 8) - offset;
 312
 313       /* Store the stack pointer.  */
 314       write_memory_unsigned_integer (sp_addr, 8, sp);
 315
 316       /* The stack pointer was (potentially) modified.  Make sure we
 317          build a proper stack frame.  */
 318       regnum = -1;
 319     }
 320
 321   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 322     {
 323       if (amd64obsd_uthread_reg_offset[i] != -1
 324           && (regnum == -1 || regnum == i))
 325         {
 326           /* Fetch stack pointer from thread structure (if we didn't
 327              calculate it already).  */
 328           if (sp == 0)
 329             sp = read_memory_unsigned_integer (sp_addr, 8);
 330
 331           /* Write the register into the stack frame.  */
 332           regcache_raw_collect (regcache, i, buf);
 333           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 334         }
 335     }
 336 }
 337 /* Kernel debugging support.  */
 338
 339 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 340    `struct sigcontext'.  */
 341 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 342
 343 static struct trad_frame_cache *
 344 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 345 {
 346   struct trad_frame_cache *cache;
 347   CORE_ADDR func, sp, addr;
 348   ULONGEST cs;
 349   char *name;
 350   int i;
 351
 352   if (*this_cache)
 353     return *this_cache;
 354
 355   cache = trad_frame_cache_zalloc (this_frame);
 356   *this_cache = cache;
 357
 358   func = get_frame_func (this_frame);
 359   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 360
 361   find_pc_partial_function (func, &name, NULL, NULL);
 362   if (name && strncmp (name, "Xintr", 5) == 0)
 363     addr = sp + 8;              /* It's an interrupt frame.  */
 364   else
 365     addr = sp;
 366
 367   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 368     if (amd64obsd_tf_reg_offset[i] != -1)
 369       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 370
 371   /* Read %cs from trap frame.  */
 372   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 373   cs = read_memory_unsigned_integer (addr, 8);
 374   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 375     {
 376       /* Trap from user space; terminate backtrace.  */
 377       trad_frame_set_id (cache, null_frame_id);
 378     }
 379   else
 380     {
 381       /* Construct the frame ID using the function start.  */
 382       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 383     }
 384
 385   return cache;
 386 }
 387
 388 static void
 389 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 390                              void **this_cache, struct frame_id *this_id)
 391 {
 392   struct trad_frame_cache *cache =
 393     amd64obsd_trapframe_cache (this_frame, this_cache);
 394
 395   trad_frame_get_id (cache, this_id);
 396 }
 397
 398 static struct value *
 399 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 400                                    void **this_cache, int regnum)
 401 {
 402   struct trad_frame_cache *cache =
 403     amd64obsd_trapframe_cache (this_frame, this_cache);
 404
 405   return trad_frame_get_register (cache, this_frame, regnum);
 406 }
 407
 408 static int
 409 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 410                              struct frame_info *this_frame,
 411                              void **this_prologue_cache)
 412 {
 413   ULONGEST cs;
 414   char *name;
 415
 416   /* Check Current Privilege Level and bail out if we're not executing
 417      in kernel space.  */
 418   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 419   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 420     return 0;
 421
 422   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 423   return (name && ((strcmp (name, "calltrap") == 0)
 424                    || (strcmp (name, "osyscall1") == 0)
 425                    || (strcmp (name, "Xsyscall") == 0)
 426                    || (strncmp (name, "Xintr", 5) == 0)));
 427 }
 428
 429 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 430   /* FIXME: kettenis/20051219: This really is more like an interrupt
 431      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 432      which really is not what we want here.  */
 433   NORMAL_FRAME,
 434   amd64obsd_trapframe_this_id,
 435   amd64obsd_trapframe_prev_register,
 436   NULL,
 437   amd64obsd_trapframe_sniffer
 438 };
 439 \f
 440
 441 static void
 442 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 443 {
 444   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 445
 446   amd64_init_abi (info, gdbarch);
 447
 448   /* Initialize general-purpose register set details.  */
 449   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 450   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 451   tdep->sizeof_gregset = 24 * 8;
 452
 453   set_gdbarch_regset_from_core_section (gdbarch,
 454                                         amd64obsd_regset_from_core_section);
 455
 456   tdep->jb_pc_offset = 7 * 8;
 457
 458   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 459   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 460   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 461   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 462
 463   /* OpenBSD provides a user-level threads implementation.  */
 464   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 465   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 466
 467   /* OpenBSD uses SVR4-style shared libraries.  */
 468   set_solib_svr4_fetch_link_map_offsets
 469     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 470
 471   /* Unwind kernel trap frames correctly.  */
 472   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 473 }
 474 \f
 475
 476 /* Provide a prototype to silence -Wmissing-prototypes.  */
 477 void _initialize_amd64obsd_tdep (void);
 478
 479 void
 480 _initialize_amd64obsd_tdep (void)
 481 {
 482   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 483   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 484
 485   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 486                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 487
 488   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 489   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 490                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 491 }