gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007 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 2 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, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "frame-unwind.h"
  25 #include "gdbcore.h"
  26 #include "symtab.h"
  27 #include "objfiles.h"
  28 #include "osabi.h"
  29 #include "regcache.h"
  30 #include "regset.h"
  31 #include "target.h"
  32 #include "trad-frame.h"
  33
  34 #include "gdb_assert.h"
  35 #include "gdb_string.h"
  36
  37 #include "amd64-tdep.h"
  38 #include "i387-tdep.h"
  39 #include "solib-svr4.h"
  40 #include "bsd-uthread.h"
  41
  42 /* Support for core dumps.  */
  43
  44 static void
  45 amd64obsd_supply_regset (const struct regset *regset,
  46                          struct regcache *regcache, int regnum,
  47                          const void *regs, size_t len)
  48 {
  49   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  50
  51   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  52
  53   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  54   amd64_supply_fxsave (regcache, regnum,
  55                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  56 }
  57
  58 static const struct regset *
  59 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  60                                     const char *sect_name, size_t sect_size)
  61 {
  62   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  63
  64   /* OpenBSD core dumps don't use seperate register sets for the
  65      general-purpose and floating-point registers.  */
  66
  67   if (strcmp (sect_name, ".reg") == 0
  68       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  69     {
  70       if (tdep->gregset == NULL)
  71         tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);
  72       return tdep->gregset;
  73     }
  74
  75   return NULL;
  76 }
  77 \f
  78
  79 /* Support for signal handlers.  */
  80
  81 /* Default page size.  */
  82 static const int amd64obsd_page_size = 4096;
  83
  84 /* Return whether the frame preceding NEXT_FRAME corresponds to an
  85    OpenBSD sigtramp routine.  */
  86
  87 static int
  88 amd64obsd_sigtramp_p (struct frame_info *next_frame)
  89 {
  90   CORE_ADDR pc = frame_pc_unwind (next_frame);
  91   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  92   const gdb_byte sigreturn[] =
  93   {
  94     0x48, 0xc7, 0xc0,
  95     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  96     0xcd, 0x80                  /* int $0x80 */
  97   };
  98   size_t buflen = (sizeof sigreturn) + 1;
  99   gdb_byte *buf;
 100   char *name;
 101
 102   /* If the function has a valid symbol name, it isn't a
 103      trampoline.  */
 104   find_pc_partial_function (pc, &name, NULL, NULL);
 105   if (name != NULL)
 106     return 0;
 107
 108   /* If the function lives in a valid section (even without a starting
 109      point) it isn't a trampoline.  */
 110   if (find_pc_section (pc) != NULL)
 111     return 0;
 112
 113   /* If we can't read the instructions at START_PC, return zero.  */
 114   buf = alloca ((sizeof sigreturn) + 1);
 115   if (!safe_frame_unwind_memory (next_frame, start_pc + 6, buf, buflen))
 116     return 0;
 117
 118   /* Check for sigreturn(2).  Depending on how the assembler encoded
 119      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 120      7.  */
 121   if (memcmp (buf, sigreturn, sizeof sigreturn)
 122       && memcpy (buf + 1, sigreturn, sizeof sigreturn))
 123     return 0;
 124
 125   return 1;
 126 }
 127
 128 /* Assuming NEXT_FRAME is for a frame following a BSD sigtramp
 129    routine, return the address of the associated sigcontext structure.  */
 130
 131 static CORE_ADDR
 132 amd64obsd_sigcontext_addr (struct frame_info *next_frame)
 133 {
 134   CORE_ADDR pc = frame_pc_unwind (next_frame);
 135   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 136
 137   /* The %rsp register points at `struct sigcontext' upon entry of a
 138      signal trampoline.  The relevant part of the trampoline is
 139
 140         call    *%rax
 141         movq    %rsp, %rdi
 142         pushq   %rdi
 143         movq    $SYS_sigreturn,%rax
 144         int     $0x80
 145
 146      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 147      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 148
 149   if (offset > 5)
 150     return frame_unwind_register_unsigned (next_frame, AMD64_RDI_REGNUM);
 151   else
 152     return frame_unwind_register_unsigned (next_frame, AMD64_RSP_REGNUM);
 153 }
 154 \f
 155 /* OpenBSD 3.5 or later.  */
 156
 157 /* Mapping between the general-purpose registers in `struct reg'
 158    format and GDB's register cache layout.  */
 159
 160 /* From <machine/reg.h>.  */
 161 int amd64obsd_r_reg_offset[] =
 162 {
 163   14 * 8,                       /* %rax */
 164   13 * 8,                       /* %rbx */
 165   3 * 8,                        /* %rcx */
 166   2 * 8,                        /* %rdx */
 167   1 * 8,                        /* %rsi */
 168   0 * 8,                        /* %rdi */
 169   12 * 8,                       /* %rbp */
 170   15 * 8,                       /* %rsp */
 171   4 * 8,                        /* %r8 .. */
 172   5 * 8,
 173   6 * 8,
 174   7 * 8,
 175   8 * 8,
 176   9 * 8,
 177   10 * 8,
 178   11 * 8,                       /* ... %r15 */
 179   16 * 8,                       /* %rip */
 180   17 * 8,                       /* %eflags */
 181   18 * 8,                       /* %cs */
 182   19 * 8,                       /* %ss */
 183   20 * 8,                       /* %ds */
 184   21 * 8,                       /* %es */
 185   22 * 8,                       /* %fs */
 186   23 * 8                        /* %gs */
 187 };
 188
 189 /* From <machine/signal.h>.  */
 190 static int amd64obsd_sc_reg_offset[] =
 191 {
 192   14 * 8,                       /* %rax */
 193   13 * 8,                       /* %rbx */
 194   3 * 8,                        /* %rcx */
 195   2 * 8,                        /* %rdx */
 196   1 * 8,                        /* %rsi */
 197   0 * 8,                        /* %rdi */
 198   12 * 8,                       /* %rbp */
 199   24 * 8,                       /* %rsp */
 200   4 * 8,                        /* %r8 ... */
 201   5 * 8,
 202   6 * 8,
 203   7 * 8,
 204   8 * 8,
 205   9 * 8,
 206   10 * 8,
 207   11 * 8,                       /* ... %r15 */
 208   21 * 8,                       /* %rip */
 209   23 * 8,                       /* %eflags */
 210   22 * 8,                       /* %cs */
 211   25 * 8,                       /* %ss */
 212   18 * 8,                       /* %ds */
 213   17 * 8,                       /* %es */
 214   16 * 8,                       /* %fs */
 215   15 * 8                        /* %gs */
 216 };
 217
 218 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 219 static int amd64obsd_uthread_reg_offset[] =
 220 {
 221   19 * 8,                       /* %rax */
 222   16 * 8,                       /* %rbx */
 223   18 * 8,                       /* %rcx */
 224   17 * 8,                       /* %rdx */
 225   14 * 8,                       /* %rsi */
 226   13 * 8,                       /* %rdi */
 227   15 * 8,                       /* %rbp */
 228   -1,                           /* %rsp */
 229   12 * 8,                       /* %r8 ... */
 230   11 * 8,
 231   10 * 8,
 232   9 * 8,
 233   8 * 8,
 234   7 * 8,
 235   6 * 8,
 236   5 * 8,                        /* ... %r15 */
 237   20 * 8,                       /* %rip */
 238   4 * 8,                        /* %eflags */
 239   21 * 8,                       /* %cs */
 240   -1,                           /* %ss */
 241   3 * 8,                        /* %ds */
 242   2 * 8,                        /* %es */
 243   1 * 8,                        /* %fs */
 244   0 * 8                         /* %gs */
 245 };
 246
 247 /* Offset within the thread structure where we can find the saved
 248    stack pointer (%esp).  */
 249 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 250
 251 static void
 252 amd64obsd_supply_uthread (struct regcache *regcache,
 253                           int regnum, CORE_ADDR addr)
 254 {
 255   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 256   CORE_ADDR sp = 0;
 257   gdb_byte buf[8];
 258   int i;
 259
 260   gdb_assert (regnum >= -1);
 261
 262   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 263     {
 264       int offset;
 265
 266       /* Fetch stack pointer from thread structure.  */
 267       sp = read_memory_unsigned_integer (sp_addr, 8);
 268
 269       /* Adjust the stack pointer such that it looks as if we just
 270          returned from _thread_machdep_switch.  */
 271       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 272       store_unsigned_integer (buf, 8, sp + offset);
 273       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 274     }
 275
 276   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 277     {
 278       if (amd64obsd_uthread_reg_offset[i] != -1
 279           && (regnum == -1 || regnum == i))
 280         {
 281           /* Fetch stack pointer from thread structure (if we didn't
 282              do so already).  */
 283           if (sp == 0)
 284             sp = read_memory_unsigned_integer (sp_addr, 8);
 285
 286           /* Read the saved register from the stack frame.  */
 287           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 288           regcache_raw_supply (regcache, i, buf);
 289         }
 290     }
 291 }
 292
 293 static void
 294 amd64obsd_collect_uthread (const struct regcache *regcache,
 295                            int regnum, CORE_ADDR addr)
 296 {
 297   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 298   CORE_ADDR sp = 0;
 299   gdb_byte buf[8];
 300   int i;
 301
 302   gdb_assert (regnum >= -1);
 303
 304   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 305     {
 306       int offset;
 307
 308       /* Calculate the stack pointer (frame pointer) that will be
 309          stored into the thread structure.  */
 310       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 311       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 312       sp = extract_unsigned_integer (buf, 8) - offset;
 313
 314       /* Store the stack pointer.  */
 315       write_memory_unsigned_integer (sp_addr, 8, sp);
 316
 317       /* The stack pointer was (potentially) modified.  Make sure we
 318          build a proper stack frame.  */
 319       regnum = -1;
 320     }
 321
 322   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 323     {
 324       if (amd64obsd_uthread_reg_offset[i] != -1
 325           && (regnum == -1 || regnum == i))
 326         {
 327           /* Fetch stack pointer from thread structure (if we didn't
 328              calculate it already).  */
 329           if (sp == 0)
 330             sp = read_memory_unsigned_integer (sp_addr, 8);
 331
 332           /* Write the register into the stack frame.  */
 333           regcache_raw_collect (regcache, i, buf);
 334           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 335         }
 336     }
 337 }
 338 /* Kernel debugging support.  */
 339
 340 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 341    `struct sigcontext'.  */
 342 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 343
 344 static struct trad_frame_cache *
 345 amd64obsd_trapframe_cache(struct frame_info *next_frame, void **this_cache)
 346 {
 347   struct trad_frame_cache *cache;
 348   CORE_ADDR func, sp, addr;
 349   ULONGEST cs;
 350   char *name;
 351   int i;
 352
 353   if (*this_cache)
 354     return *this_cache;
 355
 356   cache = trad_frame_cache_zalloc (next_frame);
 357   *this_cache = cache;
 358
 359   /* NORMAL_FRAME matches the type in amd64obsd_trapframe_unwind, but
 360      SIGTRAMP_FRAME might be more appropriate.  */
 361   func = frame_func_unwind (next_frame, NORMAL_FRAME);
 362   sp = frame_unwind_register_unsigned (next_frame, AMD64_RSP_REGNUM);
 363
 364   find_pc_partial_function (func, &name, NULL, NULL);
 365   if (name && strncmp (name, "Xintr", 5) == 0)
 366     addr = sp + 8;              /* It's an interrupt frame.  */
 367   else
 368     addr = sp;
 369
 370   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 371     if (amd64obsd_tf_reg_offset[i] != -1)
 372       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 373
 374   /* Read %cs from trap frame.  */
 375   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 376   cs = read_memory_unsigned_integer (addr, 8);
 377   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 378     {
 379       /* Trap from user space; terminate backtrace.  */
 380       trad_frame_set_id (cache, null_frame_id);
 381     }
 382   else
 383     {
 384       /* Construct the frame ID using the function start.  */
 385       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 386     }
 387
 388   return cache;
 389 }
 390
 391 static void
 392 amd64obsd_trapframe_this_id (struct frame_info *next_frame,
 393                              void **this_cache, struct frame_id *this_id)
 394 {
 395   struct trad_frame_cache *cache =
 396     amd64obsd_trapframe_cache (next_frame, this_cache);
 397
 398   trad_frame_get_id (cache, this_id);
 399 }
 400
 401 static void
 402 amd64obsd_trapframe_prev_register (struct frame_info *next_frame,
 403                                    void **this_cache, int regnum,
 404                                    int *optimizedp, enum lval_type *lvalp,
 405                                    CORE_ADDR *addrp, int *realnump,
 406                                    gdb_byte *valuep)
 407 {
 408   struct trad_frame_cache *cache =
 409     amd64obsd_trapframe_cache (next_frame, this_cache);
 410
 411   trad_frame_get_register (cache, next_frame, regnum,
 412                            optimizedp, lvalp, addrp, realnump, valuep);
 413 }
 414
 415 static int
 416 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 417                              struct frame_info *next_frame,
 418                              void **this_prologue_cache)
 419 {
 420   ULONGEST cs;
 421   char *name;
 422
 423   /* Check Current Privilege Level and bail out if we're not executing
 424      in kernel space.  */
 425   cs = frame_unwind_register_unsigned (next_frame, AMD64_CS_REGNUM);
 426   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 427     return 0;
 428
 429   find_pc_partial_function (frame_pc_unwind (next_frame), &name, NULL, NULL);
 430   return (name && ((strcmp (name, "calltrap") == 0)
 431                    || (strcmp (name, "osyscall1") == 0)
 432                    || (strcmp (name, "Xsyscall") == 0)
 433                    || (strncmp (name, "Xintr", 5) == 0)));
 434 }
 435
 436 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 437   /* FIXME: kettenis/20051219: This really is more like an interrupt
 438      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 439      which really is not what we want here.  */
 440   NORMAL_FRAME,
 441   amd64obsd_trapframe_this_id,
 442   amd64obsd_trapframe_prev_register,
 443   NULL,
 444   amd64obsd_trapframe_sniffer
 445 };
 446 \f
 447
 448 static void
 449 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 450 {
 451   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 452
 453   amd64_init_abi (info, gdbarch);
 454
 455   /* Initialize general-purpose register set details.  */
 456   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 457   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 458   tdep->sizeof_gregset = 24 * 8;
 459
 460   set_gdbarch_regset_from_core_section (gdbarch,
 461                                         amd64obsd_regset_from_core_section);
 462
 463   tdep->jb_pc_offset = 7 * 8;
 464
 465   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 466   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 467   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 468   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 469
 470   /* OpenBSD provides a user-level threads implementation.  */
 471   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 472   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 473
 474   /* OpenBSD uses SVR4-style shared libraries.  */
 475   set_solib_svr4_fetch_link_map_offsets
 476     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 477
 478   /* Unwind kernel trap frames correctly.  */
 479   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 480 }
 481 \f
 482
 483 /* Provide a prototype to silence -Wmissing-prototypes.  */
 484 void _initialize_amd64obsd_tdep (void);
 485
 486 void
 487 _initialize_amd64obsd_tdep (void)
 488 {
 489   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 490   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 491
 492   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 493                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 494
 495   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 496   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 497                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 498 }