gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003-2005, 2007-2012 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 "frame.h"
  22 #include "frame-unwind.h"
  23 #include "gdbcore.h"
  24 #include "symtab.h"
  25 #include "objfiles.h"
  26 #include "osabi.h"
  27 #include "regcache.h"
  28 #include "regset.h"
  29 #include "target.h"
  30 #include "trad-frame.h"
  31
  32 #include "gdb_assert.h"
  33 #include "gdb_string.h"
  34
  35 #include "amd64-tdep.h"
  36 #include "i387-tdep.h"
  37 #include "solib-svr4.h"
  38 #include "bsd-uthread.h"
  39
  40 /* Support for core dumps.  */
  41
  42 static void
  43 amd64obsd_supply_regset (const struct regset *regset,
  44                          struct regcache *regcache, int regnum,
  45                          const void *regs, size_t len)
  46 {
  47   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  48
  49   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  50
  51   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  52   amd64_supply_fxsave (regcache, regnum,
  53                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  54 }
  55
  56 static const struct regset *
  57 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  58                                     const char *sect_name, size_t sect_size)
  59 {
  60   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  61
  62   /* OpenBSD core dumps don't use seperate register sets for the
  63      general-purpose and floating-point registers.  */
  64
  65   if (strcmp (sect_name, ".reg") == 0
  66       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  67     {
  68       if (tdep->gregset == NULL)
  69         tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);
  70       return tdep->gregset;
  71     }
  72
  73   return NULL;
  74 }
  75 \f
  76
  77 /* Support for signal handlers.  */
  78
  79 /* Default page size.  */
  80 static const int amd64obsd_page_size = 4096;
  81
  82 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  83    routine.  */
  84
  85 static int
  86 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  87 {
  88   CORE_ADDR pc = get_frame_pc (this_frame);
  89   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  90   const gdb_byte osigreturn[] =
  91   {
  92     0x48, 0xc7, 0xc0,
  93     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  94     0xcd, 0x80                  /* int $0x80 */
  95   };
  96   const gdb_byte sigreturn[] =
  97   {
  98     0x48, 0xc7, 0xc0,
  99     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
 100     0x0f, 0x05                  /* syscall */
 101   };
 102   size_t buflen = (sizeof sigreturn) + 1;
 103   gdb_byte *buf;
 104   const char *name;
 105
 106   /* If the function has a valid symbol name, it isn't a
 107      trampoline.  */
 108   find_pc_partial_function (pc, &name, NULL, NULL);
 109   if (name != NULL)
 110     return 0;
 111
 112   /* If the function lives in a valid section (even without a starting
 113      point) it isn't a trampoline.  */
 114   if (find_pc_section (pc) != NULL)
 115     return 0;
 116
 117   /* If we can't read the instructions at START_PC, return zero.  */
 118   buf = alloca ((sizeof sigreturn) + 1);
 119   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 120     return 0;
 121
 122   /* Check for sigreturn(2).  Depending on how the assembler encoded
 123      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 124      7.  OpenBSD 5.0 and later use the `syscall' instruction.  Older
 125      versions use `int $0x80'.  Check for both.  */
 126   if (memcmp (buf, sigreturn, sizeof sigreturn)
 127       && memcmp (buf + 1, sigreturn, sizeof sigreturn)
 128       && memcmp (buf, osigreturn, sizeof osigreturn)
 129       && memcmp (buf + 1, osigreturn, sizeof osigreturn))
 130     return 0;
 131
 132   return 1;
 133 }
 134
 135 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 136    address of the associated sigcontext structure.  */
 137
 138 static CORE_ADDR
 139 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 140 {
 141   CORE_ADDR pc = get_frame_pc (this_frame);
 142   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 143
 144   /* The %rsp register points at `struct sigcontext' upon entry of a
 145      signal trampoline.  The relevant part of the trampoline is
 146
 147         call    *%rax
 148         movq    %rsp, %rdi
 149         pushq   %rdi
 150         movq    $SYS_sigreturn,%rax
 151         int     $0x80
 152
 153      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 154      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 155
 156   if (offset > 5)
 157     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 158   else
 159     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 160 }
 161 \f
 162 /* OpenBSD 3.5 or later.  */
 163
 164 /* Mapping between the general-purpose registers in `struct reg'
 165    format and GDB's register cache layout.  */
 166
 167 /* From <machine/reg.h>.  */
 168 int amd64obsd_r_reg_offset[] =
 169 {
 170   14 * 8,                       /* %rax */
 171   13 * 8,                       /* %rbx */
 172   3 * 8,                        /* %rcx */
 173   2 * 8,                        /* %rdx */
 174   1 * 8,                        /* %rsi */
 175   0 * 8,                        /* %rdi */
 176   12 * 8,                       /* %rbp */
 177   15 * 8,                       /* %rsp */
 178   4 * 8,                        /* %r8 ..  */
 179   5 * 8,
 180   6 * 8,
 181   7 * 8,
 182   8 * 8,
 183   9 * 8,
 184   10 * 8,
 185   11 * 8,                       /* ... %r15 */
 186   16 * 8,                       /* %rip */
 187   17 * 8,                       /* %eflags */
 188   18 * 8,                       /* %cs */
 189   19 * 8,                       /* %ss */
 190   20 * 8,                       /* %ds */
 191   21 * 8,                       /* %es */
 192   22 * 8,                       /* %fs */
 193   23 * 8                        /* %gs */
 194 };
 195
 196 /* From <machine/signal.h>.  */
 197 static int amd64obsd_sc_reg_offset[] =
 198 {
 199   14 * 8,                       /* %rax */
 200   13 * 8,                       /* %rbx */
 201   3 * 8,                        /* %rcx */
 202   2 * 8,                        /* %rdx */
 203   1 * 8,                        /* %rsi */
 204   0 * 8,                        /* %rdi */
 205   12 * 8,                       /* %rbp */
 206   24 * 8,                       /* %rsp */
 207   4 * 8,                        /* %r8 ...  */
 208   5 * 8,
 209   6 * 8,
 210   7 * 8,
 211   8 * 8,
 212   9 * 8,
 213   10 * 8,
 214   11 * 8,                       /* ... %r15 */
 215   21 * 8,                       /* %rip */
 216   23 * 8,                       /* %eflags */
 217   22 * 8,                       /* %cs */
 218   25 * 8,                       /* %ss */
 219   18 * 8,                       /* %ds */
 220   17 * 8,                       /* %es */
 221   16 * 8,                       /* %fs */
 222   15 * 8                        /* %gs */
 223 };
 224
 225 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 226 static int amd64obsd_uthread_reg_offset[] =
 227 {
 228   19 * 8,                       /* %rax */
 229   16 * 8,                       /* %rbx */
 230   18 * 8,                       /* %rcx */
 231   17 * 8,                       /* %rdx */
 232   14 * 8,                       /* %rsi */
 233   13 * 8,                       /* %rdi */
 234   15 * 8,                       /* %rbp */
 235   -1,                           /* %rsp */
 236   12 * 8,                       /* %r8 ...  */
 237   11 * 8,
 238   10 * 8,
 239   9 * 8,
 240   8 * 8,
 241   7 * 8,
 242   6 * 8,
 243   5 * 8,                        /* ... %r15 */
 244   20 * 8,                       /* %rip */
 245   4 * 8,                        /* %eflags */
 246   21 * 8,                       /* %cs */
 247   -1,                           /* %ss */
 248   3 * 8,                        /* %ds */
 249   2 * 8,                        /* %es */
 250   1 * 8,                        /* %fs */
 251   0 * 8                         /* %gs */
 252 };
 253
 254 /* Offset within the thread structure where we can find the saved
 255    stack pointer (%esp).  */
 256 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 257
 258 static void
 259 amd64obsd_supply_uthread (struct regcache *regcache,
 260                           int regnum, CORE_ADDR addr)
 261 {
 262   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 263   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 264   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 265   CORE_ADDR sp = 0;
 266   gdb_byte buf[8];
 267   int i;
 268
 269   gdb_assert (regnum >= -1);
 270
 271   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 272     {
 273       int offset;
 274
 275       /* Fetch stack pointer from thread structure.  */
 276       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 277
 278       /* Adjust the stack pointer such that it looks as if we just
 279          returned from _thread_machdep_switch.  */
 280       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 281       store_unsigned_integer (buf, 8, byte_order, sp + offset);
 282       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 283     }
 284
 285   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 286     {
 287       if (amd64obsd_uthread_reg_offset[i] != -1
 288           && (regnum == -1 || regnum == i))
 289         {
 290           /* Fetch stack pointer from thread structure (if we didn't
 291              do so already).  */
 292           if (sp == 0)
 293             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 294
 295           /* Read the saved register from the stack frame.  */
 296           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 297           regcache_raw_supply (regcache, i, buf);
 298         }
 299     }
 300 }
 301
 302 static void
 303 amd64obsd_collect_uthread (const struct regcache *regcache,
 304                            int regnum, CORE_ADDR addr)
 305 {
 306   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 307   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 308   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 309   CORE_ADDR sp = 0;
 310   gdb_byte buf[8];
 311   int i;
 312
 313   gdb_assert (regnum >= -1);
 314
 315   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 316     {
 317       int offset;
 318
 319       /* Calculate the stack pointer (frame pointer) that will be
 320          stored into the thread structure.  */
 321       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 322       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 323       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
 324
 325       /* Store the stack pointer.  */
 326       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
 327
 328       /* The stack pointer was (potentially) modified.  Make sure we
 329          build a proper stack frame.  */
 330       regnum = -1;
 331     }
 332
 333   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 334     {
 335       if (amd64obsd_uthread_reg_offset[i] != -1
 336           && (regnum == -1 || regnum == i))
 337         {
 338           /* Fetch stack pointer from thread structure (if we didn't
 339              calculate it already).  */
 340           if (sp == 0)
 341             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 342
 343           /* Write the register into the stack frame.  */
 344           regcache_raw_collect (regcache, i, buf);
 345           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 346         }
 347     }
 348 }
 349 /* Kernel debugging support.  */
 350
 351 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 352    `struct sigcontext'.  */
 353 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 354
 355 static struct trad_frame_cache *
 356 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 357 {
 358   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 359   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 360   struct trad_frame_cache *cache;
 361   CORE_ADDR func, sp, addr;
 362   ULONGEST cs;
 363   const char *name;
 364   int i;
 365
 366   if (*this_cache)
 367     return *this_cache;
 368
 369   cache = trad_frame_cache_zalloc (this_frame);
 370   *this_cache = cache;
 371
 372   func = get_frame_func (this_frame);
 373   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 374
 375   find_pc_partial_function (func, &name, NULL, NULL);
 376   if (name && strncmp (name, "Xintr", 5) == 0)
 377     addr = sp + 8;              /* It's an interrupt frame.  */
 378   else
 379     addr = sp;
 380
 381   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 382     if (amd64obsd_tf_reg_offset[i] != -1)
 383       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 384
 385   /* Read %cs from trap frame.  */
 386   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 387   cs = read_memory_unsigned_integer (addr, 8, byte_order);
 388   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 389     {
 390       /* Trap from user space; terminate backtrace.  */
 391       trad_frame_set_id (cache, outer_frame_id);
 392     }
 393   else
 394     {
 395       /* Construct the frame ID using the function start.  */
 396       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 397     }
 398
 399   return cache;
 400 }
 401
 402 static void
 403 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 404                              void **this_cache, struct frame_id *this_id)
 405 {
 406   struct trad_frame_cache *cache =
 407     amd64obsd_trapframe_cache (this_frame, this_cache);
 408
 409   trad_frame_get_id (cache, this_id);
 410 }
 411
 412 static struct value *
 413 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 414                                    void **this_cache, int regnum)
 415 {
 416   struct trad_frame_cache *cache =
 417     amd64obsd_trapframe_cache (this_frame, this_cache);
 418
 419   return trad_frame_get_register (cache, this_frame, regnum);
 420 }
 421
 422 static int
 423 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 424                              struct frame_info *this_frame,
 425                              void **this_prologue_cache)
 426 {
 427   ULONGEST cs;
 428   const char *name;
 429
 430   /* Check Current Privilege Level and bail out if we're not executing
 431      in kernel space.  */
 432   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 433   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 434     return 0;
 435
 436   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 437   return (name && ((strcmp (name, "calltrap") == 0)
 438                    || (strcmp (name, "osyscall1") == 0)
 439                    || (strcmp (name, "Xsyscall") == 0)
 440                    || (strncmp (name, "Xintr", 5) == 0)));
 441 }
 442
 443 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 444   /* FIXME: kettenis/20051219: This really is more like an interrupt
 445      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 446      which really is not what we want here.  */
 447   NORMAL_FRAME,
 448   default_frame_unwind_stop_reason,
 449   amd64obsd_trapframe_this_id,
 450   amd64obsd_trapframe_prev_register,
 451   NULL,
 452   amd64obsd_trapframe_sniffer
 453 };
 454 \f
 455
 456 static void
 457 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 458 {
 459   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 460
 461   amd64_init_abi (info, gdbarch);
 462
 463   /* Initialize general-purpose register set details.  */
 464   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 465   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 466   tdep->sizeof_gregset = 24 * 8;
 467
 468   tdep->jb_pc_offset = 7 * 8;
 469
 470   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 471   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 472   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 473   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 474
 475   /* OpenBSD provides a user-level threads implementation.  */
 476   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 477   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 478
 479   /* OpenBSD uses SVR4-style shared libraries.  */
 480   set_solib_svr4_fetch_link_map_offsets
 481     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 482
 483   /* Unwind kernel trap frames correctly.  */
 484   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 485 }
 486
 487 /* Traditional (a.out) NetBSD-style core dumps.  */
 488
 489 static void
 490 amd64obsd_core_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 491 {
 492   amd64obsd_init_abi (info, gdbarch);
 493
 494   set_gdbarch_regset_from_core_section
 495     (gdbarch, amd64obsd_regset_from_core_section);
 496 }
 497 \f
 498
 499 /* Provide a prototype to silence -Wmissing-prototypes.  */
 500 void _initialize_amd64obsd_tdep (void);
 501
 502 void
 503 _initialize_amd64obsd_tdep (void)
 504 {
 505   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 506   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 507
 508   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 509                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 510
 511   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 512   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 513                           GDB_OSABI_NETBSD_AOUT, amd64obsd_core_init_abi);
 514 }