gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003-2014 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 <string.h>
  33
  34 #include "obsd-tdep.h"
  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   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  48   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  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 amd64obsd_combined_regset =
  58   {
  59     NULL, amd64obsd_supply_regset, NULL
  60   };
  61
  62 static const struct regset *
  63 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  64                                     const char *sect_name, size_t sect_size)
  65 {
  66   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  67
  68   /* OpenBSD core dumps don't use seperate register sets for the
  69      general-purpose and floating-point registers.  */
  70
  71   if (strcmp (sect_name, ".reg") == 0
  72       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  73     return &amd64obsd_combined_regset;
  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 THIS_FRAME corresponds to an OpenBSD sigtramp
  85    routine.  */
  86
  87 static int
  88 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  89 {
  90   CORE_ADDR pc = get_frame_pc (this_frame);
  91   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  92   const gdb_byte osigreturn[] =
  93   {
  94     0x48, 0xc7, 0xc0,
  95     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  96     0xcd, 0x80                  /* int $0x80 */
  97   };
  98   const gdb_byte sigreturn[] =
  99   {
 100     0x48, 0xc7, 0xc0,
 101     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
 102     0x0f, 0x05                  /* syscall */
 103   };
 104   size_t buflen = (sizeof sigreturn) + 1;
 105   gdb_byte *buf;
 106   const char *name;
 107
 108   /* If the function has a valid symbol name, it isn't a
 109      trampoline.  */
 110   find_pc_partial_function (pc, &name, NULL, NULL);
 111   if (name != NULL)
 112     return 0;
 113
 114   /* If the function lives in a valid section (even without a starting
 115      point) it isn't a trampoline.  */
 116   if (find_pc_section (pc) != NULL)
 117     return 0;
 118
 119   /* If we can't read the instructions at START_PC, return zero.  */
 120   buf = alloca ((sizeof sigreturn) + 1);
 121   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 122     return 0;
 123
 124   /* Check for sigreturn(2).  Depending on how the assembler encoded
 125      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 126      7.  OpenBSD 5.0 and later use the `syscall' instruction.  Older
 127      versions use `int $0x80'.  Check for both.  */
 128   if (memcmp (buf, sigreturn, sizeof sigreturn)
 129       && memcmp (buf + 1, sigreturn, sizeof sigreturn)
 130       && memcmp (buf, osigreturn, sizeof osigreturn)
 131       && memcmp (buf + 1, osigreturn, sizeof osigreturn))
 132     return 0;
 133
 134   return 1;
 135 }
 136
 137 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 138    address of the associated sigcontext structure.  */
 139
 140 static CORE_ADDR
 141 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 142 {
 143   CORE_ADDR pc = get_frame_pc (this_frame);
 144   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 145
 146   /* The %rsp register points at `struct sigcontext' upon entry of a
 147      signal trampoline.  The relevant part of the trampoline is
 148
 149         call    *%rax
 150         movq    %rsp, %rdi
 151         pushq   %rdi
 152         movq    $SYS_sigreturn,%rax
 153         int     $0x80
 154
 155      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 156      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 157
 158   if (offset > 5)
 159     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 160   else
 161     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 162 }
 163 \f
 164 /* OpenBSD 3.5 or later.  */
 165
 166 /* Mapping between the general-purpose registers in `struct reg'
 167    format and GDB's register cache layout.  */
 168
 169 /* From <machine/reg.h>.  */
 170 int amd64obsd_r_reg_offset[] =
 171 {
 172   14 * 8,                       /* %rax */
 173   13 * 8,                       /* %rbx */
 174   3 * 8,                        /* %rcx */
 175   2 * 8,                        /* %rdx */
 176   1 * 8,                        /* %rsi */
 177   0 * 8,                        /* %rdi */
 178   12 * 8,                       /* %rbp */
 179   15 * 8,                       /* %rsp */
 180   4 * 8,                        /* %r8 ..  */
 181   5 * 8,
 182   6 * 8,
 183   7 * 8,
 184   8 * 8,
 185   9 * 8,
 186   10 * 8,
 187   11 * 8,                       /* ... %r15 */
 188   16 * 8,                       /* %rip */
 189   17 * 8,                       /* %eflags */
 190   18 * 8,                       /* %cs */
 191   19 * 8,                       /* %ss */
 192   20 * 8,                       /* %ds */
 193   21 * 8,                       /* %es */
 194   22 * 8,                       /* %fs */
 195   23 * 8                        /* %gs */
 196 };
 197
 198 /* From <machine/signal.h>.  */
 199 static int amd64obsd_sc_reg_offset[] =
 200 {
 201   14 * 8,                       /* %rax */
 202   13 * 8,                       /* %rbx */
 203   3 * 8,                        /* %rcx */
 204   2 * 8,                        /* %rdx */
 205   1 * 8,                        /* %rsi */
 206   0 * 8,                        /* %rdi */
 207   12 * 8,                       /* %rbp */
 208   24 * 8,                       /* %rsp */
 209   4 * 8,                        /* %r8 ...  */
 210   5 * 8,
 211   6 * 8,
 212   7 * 8,
 213   8 * 8,
 214   9 * 8,
 215   10 * 8,
 216   11 * 8,                       /* ... %r15 */
 217   21 * 8,                       /* %rip */
 218   23 * 8,                       /* %eflags */
 219   22 * 8,                       /* %cs */
 220   25 * 8,                       /* %ss */
 221   18 * 8,                       /* %ds */
 222   17 * 8,                       /* %es */
 223   16 * 8,                       /* %fs */
 224   15 * 8                        /* %gs */
 225 };
 226
 227 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 228 static int amd64obsd_uthread_reg_offset[] =
 229 {
 230   19 * 8,                       /* %rax */
 231   16 * 8,                       /* %rbx */
 232   18 * 8,                       /* %rcx */
 233   17 * 8,                       /* %rdx */
 234   14 * 8,                       /* %rsi */
 235   13 * 8,                       /* %rdi */
 236   15 * 8,                       /* %rbp */
 237   -1,                           /* %rsp */
 238   12 * 8,                       /* %r8 ...  */
 239   11 * 8,
 240   10 * 8,
 241   9 * 8,
 242   8 * 8,
 243   7 * 8,
 244   6 * 8,
 245   5 * 8,                        /* ... %r15 */
 246   20 * 8,                       /* %rip */
 247   4 * 8,                        /* %eflags */
 248   21 * 8,                       /* %cs */
 249   -1,                           /* %ss */
 250   3 * 8,                        /* %ds */
 251   2 * 8,                        /* %es */
 252   1 * 8,                        /* %fs */
 253   0 * 8                         /* %gs */
 254 };
 255
 256 /* Offset within the thread structure where we can find the saved
 257    stack pointer (%esp).  */
 258 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 259
 260 static void
 261 amd64obsd_supply_uthread (struct regcache *regcache,
 262                           int regnum, CORE_ADDR addr)
 263 {
 264   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 265   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 266   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 267   CORE_ADDR sp = 0;
 268   gdb_byte buf[8];
 269   int i;
 270
 271   gdb_assert (regnum >= -1);
 272
 273   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 274     {
 275       int offset;
 276
 277       /* Fetch stack pointer from thread structure.  */
 278       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 279
 280       /* Adjust the stack pointer such that it looks as if we just
 281          returned from _thread_machdep_switch.  */
 282       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 283       store_unsigned_integer (buf, 8, byte_order, sp + offset);
 284       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 285     }
 286
 287   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 288     {
 289       if (amd64obsd_uthread_reg_offset[i] != -1
 290           && (regnum == -1 || regnum == i))
 291         {
 292           /* Fetch stack pointer from thread structure (if we didn't
 293              do so already).  */
 294           if (sp == 0)
 295             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 296
 297           /* Read the saved register from the stack frame.  */
 298           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 299           regcache_raw_supply (regcache, i, buf);
 300         }
 301     }
 302 }
 303
 304 static void
 305 amd64obsd_collect_uthread (const struct regcache *regcache,
 306                            int regnum, CORE_ADDR addr)
 307 {
 308   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 309   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 310   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 311   CORE_ADDR sp = 0;
 312   gdb_byte buf[8];
 313   int i;
 314
 315   gdb_assert (regnum >= -1);
 316
 317   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 318     {
 319       int offset;
 320
 321       /* Calculate the stack pointer (frame pointer) that will be
 322          stored into the thread structure.  */
 323       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 324       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 325       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
 326
 327       /* Store the stack pointer.  */
 328       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
 329
 330       /* The stack pointer was (potentially) modified.  Make sure we
 331          build a proper stack frame.  */
 332       regnum = -1;
 333     }
 334
 335   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 336     {
 337       if (amd64obsd_uthread_reg_offset[i] != -1
 338           && (regnum == -1 || regnum == i))
 339         {
 340           /* Fetch stack pointer from thread structure (if we didn't
 341              calculate it already).  */
 342           if (sp == 0)
 343             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 344
 345           /* Write the register into the stack frame.  */
 346           regcache_raw_collect (regcache, i, buf);
 347           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 348         }
 349     }
 350 }
 351 /* Kernel debugging support.  */
 352
 353 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 354    `struct sigcontext'.  */
 355 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 356
 357 static struct trad_frame_cache *
 358 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 359 {
 360   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 361   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 362   struct trad_frame_cache *cache;
 363   CORE_ADDR func, sp, addr;
 364   ULONGEST cs;
 365   const char *name;
 366   int i;
 367
 368   if (*this_cache)
 369     return *this_cache;
 370
 371   cache = trad_frame_cache_zalloc (this_frame);
 372   *this_cache = cache;
 373
 374   func = get_frame_func (this_frame);
 375   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 376
 377   find_pc_partial_function (func, &name, NULL, NULL);
 378   if (name && strncmp (name, "Xintr", 5) == 0)
 379     addr = sp + 8;              /* It's an interrupt frame.  */
 380   else
 381     addr = sp;
 382
 383   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 384     if (amd64obsd_tf_reg_offset[i] != -1)
 385       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 386
 387   /* Read %cs from trap frame.  */
 388   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 389   cs = read_memory_unsigned_integer (addr, 8, byte_order);
 390   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 391     {
 392       /* Trap from user space; terminate backtrace.  */
 393       trad_frame_set_id (cache, outer_frame_id);
 394     }
 395   else
 396     {
 397       /* Construct the frame ID using the function start.  */
 398       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 399     }
 400
 401   return cache;
 402 }
 403
 404 static void
 405 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 406                              void **this_cache, struct frame_id *this_id)
 407 {
 408   struct trad_frame_cache *cache =
 409     amd64obsd_trapframe_cache (this_frame, this_cache);
 410
 411   trad_frame_get_id (cache, this_id);
 412 }
 413
 414 static struct value *
 415 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 416                                    void **this_cache, int regnum)
 417 {
 418   struct trad_frame_cache *cache =
 419     amd64obsd_trapframe_cache (this_frame, this_cache);
 420
 421   return trad_frame_get_register (cache, this_frame, regnum);
 422 }
 423
 424 static int
 425 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 426                              struct frame_info *this_frame,
 427                              void **this_prologue_cache)
 428 {
 429   ULONGEST cs;
 430   const char *name;
 431
 432   /* Check Current Privilege Level and bail out if we're not executing
 433      in kernel space.  */
 434   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 435   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 436     return 0;
 437
 438   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 439   return (name && ((strcmp (name, "calltrap") == 0)
 440                    || (strcmp (name, "osyscall1") == 0)
 441                    || (strcmp (name, "Xsyscall") == 0)
 442                    || (strncmp (name, "Xintr", 5) == 0)));
 443 }
 444
 445 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 446   /* FIXME: kettenis/20051219: This really is more like an interrupt
 447      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 448      which really is not what we want here.  */
 449   NORMAL_FRAME,
 450   default_frame_unwind_stop_reason,
 451   amd64obsd_trapframe_this_id,
 452   amd64obsd_trapframe_prev_register,
 453   NULL,
 454   amd64obsd_trapframe_sniffer
 455 };
 456 \f
 457
 458 static void
 459 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 460 {
 461   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 462
 463   amd64_init_abi (info, gdbarch);
 464   obsd_init_abi (info, gdbarch);
 465
 466   /* Initialize general-purpose register set details.  */
 467   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 468   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 469   tdep->sizeof_gregset = 24 * 8;
 470
 471   tdep->jb_pc_offset = 7 * 8;
 472
 473   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 474   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 475   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 476   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 477
 478   /* OpenBSD provides a user-level threads implementation.  */
 479   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 480   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 481
 482   /* OpenBSD uses SVR4-style shared libraries.  */
 483   set_solib_svr4_fetch_link_map_offsets
 484     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 485
 486   /* Unwind kernel trap frames correctly.  */
 487   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 488 }
 489
 490 /* Traditional (a.out) NetBSD-style core dumps.  */
 491
 492 static void
 493 amd64obsd_core_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 494 {
 495   amd64obsd_init_abi (info, gdbarch);
 496
 497   set_gdbarch_regset_from_core_section
 498     (gdbarch, amd64obsd_regset_from_core_section);
 499 }
 500 \f
 501
 502 /* Provide a prototype to silence -Wmissing-prototypes.  */
 503 void _initialize_amd64obsd_tdep (void);
 504
 505 void
 506 _initialize_amd64obsd_tdep (void)
 507 {
 508   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 509   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 510
 511   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 512                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 513
 514   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 515   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 516                           GDB_OSABI_NETBSD_AOUT, amd64obsd_core_init_abi);
 517 }