gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010
   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   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 255   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 256   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 257   CORE_ADDR sp = 0;
 258   gdb_byte buf[8];
 259   int i;
 260
 261   gdb_assert (regnum >= -1);
 262
 263   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 264     {
 265       int offset;
 266
 267       /* Fetch stack pointer from thread structure.  */
 268       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 269
 270       /* Adjust the stack pointer such that it looks as if we just
 271          returned from _thread_machdep_switch.  */
 272       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 273       store_unsigned_integer (buf, 8, byte_order, sp + offset);
 274       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 275     }
 276
 277   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 278     {
 279       if (amd64obsd_uthread_reg_offset[i] != -1
 280           && (regnum == -1 || regnum == i))
 281         {
 282           /* Fetch stack pointer from thread structure (if we didn't
 283              do so already).  */
 284           if (sp == 0)
 285             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 286
 287           /* Read the saved register from the stack frame.  */
 288           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 289           regcache_raw_supply (regcache, i, buf);
 290         }
 291     }
 292 }
 293
 294 static void
 295 amd64obsd_collect_uthread (const struct regcache *regcache,
 296                            int regnum, CORE_ADDR addr)
 297 {
 298   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 299   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 300   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 301   CORE_ADDR sp = 0;
 302   gdb_byte buf[8];
 303   int i;
 304
 305   gdb_assert (regnum >= -1);
 306
 307   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 308     {
 309       int offset;
 310
 311       /* Calculate the stack pointer (frame pointer) that will be
 312          stored into the thread structure.  */
 313       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 314       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 315       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
 316
 317       /* Store the stack pointer.  */
 318       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
 319
 320       /* The stack pointer was (potentially) modified.  Make sure we
 321          build a proper stack frame.  */
 322       regnum = -1;
 323     }
 324
 325   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 326     {
 327       if (amd64obsd_uthread_reg_offset[i] != -1
 328           && (regnum == -1 || regnum == i))
 329         {
 330           /* Fetch stack pointer from thread structure (if we didn't
 331              calculate it already).  */
 332           if (sp == 0)
 333             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 334
 335           /* Write the register into the stack frame.  */
 336           regcache_raw_collect (regcache, i, buf);
 337           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 338         }
 339     }
 340 }
 341 /* Kernel debugging support.  */
 342
 343 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 344    `struct sigcontext'.  */
 345 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 346
 347 static struct trad_frame_cache *
 348 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 349 {
 350   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 351   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 352   struct trad_frame_cache *cache;
 353   CORE_ADDR func, sp, addr;
 354   ULONGEST cs;
 355   char *name;
 356   int i;
 357
 358   if (*this_cache)
 359     return *this_cache;
 360
 361   cache = trad_frame_cache_zalloc (this_frame);
 362   *this_cache = cache;
 363
 364   func = get_frame_func (this_frame);
 365   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 366
 367   find_pc_partial_function (func, &name, NULL, NULL);
 368   if (name && strncmp (name, "Xintr", 5) == 0)
 369     addr = sp + 8;              /* It's an interrupt frame.  */
 370   else
 371     addr = sp;
 372
 373   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 374     if (amd64obsd_tf_reg_offset[i] != -1)
 375       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 376
 377   /* Read %cs from trap frame.  */
 378   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 379   cs = read_memory_unsigned_integer (addr, 8, byte_order);
 380   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 381     {
 382       /* Trap from user space; terminate backtrace.  */
 383       trad_frame_set_id (cache, outer_frame_id);
 384     }
 385   else
 386     {
 387       /* Construct the frame ID using the function start.  */
 388       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 389     }
 390
 391   return cache;
 392 }
 393
 394 static void
 395 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 396                              void **this_cache, struct frame_id *this_id)
 397 {
 398   struct trad_frame_cache *cache =
 399     amd64obsd_trapframe_cache (this_frame, this_cache);
 400
 401   trad_frame_get_id (cache, this_id);
 402 }
 403
 404 static struct value *
 405 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 406                                    void **this_cache, int regnum)
 407 {
 408   struct trad_frame_cache *cache =
 409     amd64obsd_trapframe_cache (this_frame, this_cache);
 410
 411   return trad_frame_get_register (cache, this_frame, regnum);
 412 }
 413
 414 static int
 415 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 416                              struct frame_info *this_frame,
 417                              void **this_prologue_cache)
 418 {
 419   ULONGEST cs;
 420   char *name;
 421
 422   /* Check Current Privilege Level and bail out if we're not executing
 423      in kernel space.  */
 424   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 425   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 426     return 0;
 427
 428   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 429   return (name && ((strcmp (name, "calltrap") == 0)
 430                    || (strcmp (name, "osyscall1") == 0)
 431                    || (strcmp (name, "Xsyscall") == 0)
 432                    || (strncmp (name, "Xintr", 5) == 0)));
 433 }
 434
 435 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 436   /* FIXME: kettenis/20051219: This really is more like an interrupt
 437      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 438      which really is not what we want here.  */
 439   NORMAL_FRAME,
 440   amd64obsd_trapframe_this_id,
 441   amd64obsd_trapframe_prev_register,
 442   NULL,
 443   amd64obsd_trapframe_sniffer
 444 };
 445 \f
 446
 447 static void
 448 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 449 {
 450   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 451
 452   amd64_init_abi (info, gdbarch);
 453
 454   /* Initialize general-purpose register set details.  */
 455   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 456   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 457   tdep->sizeof_gregset = 24 * 8;
 458
 459   set_gdbarch_regset_from_core_section (gdbarch,
 460                                         amd64obsd_regset_from_core_section);
 461
 462   tdep->jb_pc_offset = 7 * 8;
 463
 464   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 465   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 466   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 467   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 468
 469   /* OpenBSD provides a user-level threads implementation.  */
 470   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 471   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 472
 473   /* OpenBSD uses SVR4-style shared libraries.  */
 474   set_solib_svr4_fetch_link_map_offsets
 475     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 476
 477   /* Unwind kernel trap frames correctly.  */
 478   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 479 }
 480 \f
 481
 482 /* Provide a prototype to silence -Wmissing-prototypes.  */
 483 void _initialize_amd64obsd_tdep (void);
 484
 485 void
 486 _initialize_amd64obsd_tdep (void)
 487 {
 488   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 489   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 490
 491   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 492                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 493
 494   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 495   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 496                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 497 }