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 "gdb_assert.h"
  33 #include <string.h>
  34
  35 #include "obsd-tdep.h"
  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   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  49   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  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 amd64obsd_combined_regset =
  59   {
  60     NULL, amd64obsd_supply_regset, NULL
  61   };
  62
  63 static const struct regset *
  64 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  65                                     const char *sect_name, size_t sect_size)
  66 {
  67   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  68
  69   /* OpenBSD core dumps don't use seperate register sets for the
  70      general-purpose and floating-point registers.  */
  71
  72   if (strcmp (sect_name, ".reg") == 0
  73       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  74     return &amd64obsd_combined_regset;
  75
  76   return NULL;
  77 }
  78 \f
  79
  80 /* Support for signal handlers.  */
  81
  82 /* Default page size.  */
  83 static const int amd64obsd_page_size = 4096;
  84
  85 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  86    routine.  */
  87
  88 static int
  89 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  90 {
  91   CORE_ADDR pc = get_frame_pc (this_frame);
  92   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  93   const gdb_byte osigreturn[] =
  94   {
  95     0x48, 0xc7, 0xc0,
  96     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  97     0xcd, 0x80                  /* int $0x80 */
  98   };
  99   const gdb_byte sigreturn[] =
 100   {
 101     0x48, 0xc7, 0xc0,
 102     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
 103     0x0f, 0x05                  /* syscall */
 104   };
 105   size_t buflen = (sizeof sigreturn) + 1;
 106   gdb_byte *buf;
 107   const char *name;
 108
 109   /* If the function has a valid symbol name, it isn't a
 110      trampoline.  */
 111   find_pc_partial_function (pc, &name, NULL, NULL);
 112   if (name != NULL)
 113     return 0;
 114
 115   /* If the function lives in a valid section (even without a starting
 116      point) it isn't a trampoline.  */
 117   if (find_pc_section (pc) != NULL)
 118     return 0;
 119
 120   /* If we can't read the instructions at START_PC, return zero.  */
 121   buf = alloca ((sizeof sigreturn) + 1);
 122   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 123     return 0;
 124
 125   /* Check for sigreturn(2).  Depending on how the assembler encoded
 126      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 127      7.  OpenBSD 5.0 and later use the `syscall' instruction.  Older
 128      versions use `int $0x80'.  Check for both.  */
 129   if (memcmp (buf, sigreturn, sizeof sigreturn)
 130       && memcmp (buf + 1, sigreturn, sizeof sigreturn)
 131       && memcmp (buf, osigreturn, sizeof osigreturn)
 132       && memcmp (buf + 1, osigreturn, sizeof osigreturn))
 133     return 0;
 134
 135   return 1;
 136 }
 137
 138 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 139    address of the associated sigcontext structure.  */
 140
 141 static CORE_ADDR
 142 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 143 {
 144   CORE_ADDR pc = get_frame_pc (this_frame);
 145   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 146
 147   /* The %rsp register points at `struct sigcontext' upon entry of a
 148      signal trampoline.  The relevant part of the trampoline is
 149
 150         call    *%rax
 151         movq    %rsp, %rdi
 152         pushq   %rdi
 153         movq    $SYS_sigreturn,%rax
 154         int     $0x80
 155
 156      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 157      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 158
 159   if (offset > 5)
 160     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 161   else
 162     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 163 }
 164 \f
 165 /* OpenBSD 3.5 or later.  */
 166
 167 /* Mapping between the general-purpose registers in `struct reg'
 168    format and GDB's register cache layout.  */
 169
 170 /* From <machine/reg.h>.  */
 171 int amd64obsd_r_reg_offset[] =
 172 {
 173   14 * 8,                       /* %rax */
 174   13 * 8,                       /* %rbx */
 175   3 * 8,                        /* %rcx */
 176   2 * 8,                        /* %rdx */
 177   1 * 8,                        /* %rsi */
 178   0 * 8,                        /* %rdi */
 179   12 * 8,                       /* %rbp */
 180   15 * 8,                       /* %rsp */
 181   4 * 8,                        /* %r8 ..  */
 182   5 * 8,
 183   6 * 8,
 184   7 * 8,
 185   8 * 8,
 186   9 * 8,
 187   10 * 8,
 188   11 * 8,                       /* ... %r15 */
 189   16 * 8,                       /* %rip */
 190   17 * 8,                       /* %eflags */
 191   18 * 8,                       /* %cs */
 192   19 * 8,                       /* %ss */
 193   20 * 8,                       /* %ds */
 194   21 * 8,                       /* %es */
 195   22 * 8,                       /* %fs */
 196   23 * 8                        /* %gs */
 197 };
 198
 199 /* From <machine/signal.h>.  */
 200 static int amd64obsd_sc_reg_offset[] =
 201 {
 202   14 * 8,                       /* %rax */
 203   13 * 8,                       /* %rbx */
 204   3 * 8,                        /* %rcx */
 205   2 * 8,                        /* %rdx */
 206   1 * 8,                        /* %rsi */
 207   0 * 8,                        /* %rdi */
 208   12 * 8,                       /* %rbp */
 209   24 * 8,                       /* %rsp */
 210   4 * 8,                        /* %r8 ...  */
 211   5 * 8,
 212   6 * 8,
 213   7 * 8,
 214   8 * 8,
 215   9 * 8,
 216   10 * 8,
 217   11 * 8,                       /* ... %r15 */
 218   21 * 8,                       /* %rip */
 219   23 * 8,                       /* %eflags */
 220   22 * 8,                       /* %cs */
 221   25 * 8,                       /* %ss */
 222   18 * 8,                       /* %ds */
 223   17 * 8,                       /* %es */
 224   16 * 8,                       /* %fs */
 225   15 * 8                        /* %gs */
 226 };
 227
 228 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 229 static int amd64obsd_uthread_reg_offset[] =
 230 {
 231   19 * 8,                       /* %rax */
 232   16 * 8,                       /* %rbx */
 233   18 * 8,                       /* %rcx */
 234   17 * 8,                       /* %rdx */
 235   14 * 8,                       /* %rsi */
 236   13 * 8,                       /* %rdi */
 237   15 * 8,                       /* %rbp */
 238   -1,                           /* %rsp */
 239   12 * 8,                       /* %r8 ...  */
 240   11 * 8,
 241   10 * 8,
 242   9 * 8,
 243   8 * 8,
 244   7 * 8,
 245   6 * 8,
 246   5 * 8,                        /* ... %r15 */
 247   20 * 8,                       /* %rip */
 248   4 * 8,                        /* %eflags */
 249   21 * 8,                       /* %cs */
 250   -1,                           /* %ss */
 251   3 * 8,                        /* %ds */
 252   2 * 8,                        /* %es */
 253   1 * 8,                        /* %fs */
 254   0 * 8                         /* %gs */
 255 };
 256
 257 /* Offset within the thread structure where we can find the saved
 258    stack pointer (%esp).  */
 259 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 260
 261 static void
 262 amd64obsd_supply_uthread (struct regcache *regcache,
 263                           int regnum, CORE_ADDR addr)
 264 {
 265   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 266   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 267   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 268   CORE_ADDR sp = 0;
 269   gdb_byte buf[8];
 270   int i;
 271
 272   gdb_assert (regnum >= -1);
 273
 274   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 275     {
 276       int offset;
 277
 278       /* Fetch stack pointer from thread structure.  */
 279       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 280
 281       /* Adjust the stack pointer such that it looks as if we just
 282          returned from _thread_machdep_switch.  */
 283       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 284       store_unsigned_integer (buf, 8, byte_order, sp + offset);
 285       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 286     }
 287
 288   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 289     {
 290       if (amd64obsd_uthread_reg_offset[i] != -1
 291           && (regnum == -1 || regnum == i))
 292         {
 293           /* Fetch stack pointer from thread structure (if we didn't
 294              do so already).  */
 295           if (sp == 0)
 296             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 297
 298           /* Read the saved register from the stack frame.  */
 299           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 300           regcache_raw_supply (regcache, i, buf);
 301         }
 302     }
 303 }
 304
 305 static void
 306 amd64obsd_collect_uthread (const struct regcache *regcache,
 307                            int regnum, CORE_ADDR addr)
 308 {
 309   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 310   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 311   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 312   CORE_ADDR sp = 0;
 313   gdb_byte buf[8];
 314   int i;
 315
 316   gdb_assert (regnum >= -1);
 317
 318   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 319     {
 320       int offset;
 321
 322       /* Calculate the stack pointer (frame pointer) that will be
 323          stored into the thread structure.  */
 324       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 325       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 326       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
 327
 328       /* Store the stack pointer.  */
 329       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
 330
 331       /* The stack pointer was (potentially) modified.  Make sure we
 332          build a proper stack frame.  */
 333       regnum = -1;
 334     }
 335
 336   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 337     {
 338       if (amd64obsd_uthread_reg_offset[i] != -1
 339           && (regnum == -1 || regnum == i))
 340         {
 341           /* Fetch stack pointer from thread structure (if we didn't
 342              calculate it already).  */
 343           if (sp == 0)
 344             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 345
 346           /* Write the register into the stack frame.  */
 347           regcache_raw_collect (regcache, i, buf);
 348           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 349         }
 350     }
 351 }
 352 /* Kernel debugging support.  */
 353
 354 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 355    `struct sigcontext'.  */
 356 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 357
 358 static struct trad_frame_cache *
 359 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 360 {
 361   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 362   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 363   struct trad_frame_cache *cache;
 364   CORE_ADDR func, sp, addr;
 365   ULONGEST cs;
 366   const char *name;
 367   int i;
 368
 369   if (*this_cache)
 370     return *this_cache;
 371
 372   cache = trad_frame_cache_zalloc (this_frame);
 373   *this_cache = cache;
 374
 375   func = get_frame_func (this_frame);
 376   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 377
 378   find_pc_partial_function (func, &name, NULL, NULL);
 379   if (name && strncmp (name, "Xintr", 5) == 0)
 380     addr = sp + 8;              /* It's an interrupt frame.  */
 381   else
 382     addr = sp;
 383
 384   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 385     if (amd64obsd_tf_reg_offset[i] != -1)
 386       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 387
 388   /* Read %cs from trap frame.  */
 389   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 390   cs = read_memory_unsigned_integer (addr, 8, byte_order);
 391   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 392     {
 393       /* Trap from user space; terminate backtrace.  */
 394       trad_frame_set_id (cache, outer_frame_id);
 395     }
 396   else
 397     {
 398       /* Construct the frame ID using the function start.  */
 399       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 400     }
 401
 402   return cache;
 403 }
 404
 405 static void
 406 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 407                              void **this_cache, struct frame_id *this_id)
 408 {
 409   struct trad_frame_cache *cache =
 410     amd64obsd_trapframe_cache (this_frame, this_cache);
 411
 412   trad_frame_get_id (cache, this_id);
 413 }
 414
 415 static struct value *
 416 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 417                                    void **this_cache, int regnum)
 418 {
 419   struct trad_frame_cache *cache =
 420     amd64obsd_trapframe_cache (this_frame, this_cache);
 421
 422   return trad_frame_get_register (cache, this_frame, regnum);
 423 }
 424
 425 static int
 426 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 427                              struct frame_info *this_frame,
 428                              void **this_prologue_cache)
 429 {
 430   ULONGEST cs;
 431   const char *name;
 432
 433   /* Check Current Privilege Level and bail out if we're not executing
 434      in kernel space.  */
 435   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 436   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 437     return 0;
 438
 439   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 440   return (name && ((strcmp (name, "calltrap") == 0)
 441                    || (strcmp (name, "osyscall1") == 0)
 442                    || (strcmp (name, "Xsyscall") == 0)
 443                    || (strncmp (name, "Xintr", 5) == 0)));
 444 }
 445
 446 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 447   /* FIXME: kettenis/20051219: This really is more like an interrupt
 448      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 449      which really is not what we want here.  */
 450   NORMAL_FRAME,
 451   default_frame_unwind_stop_reason,
 452   amd64obsd_trapframe_this_id,
 453   amd64obsd_trapframe_prev_register,
 454   NULL,
 455   amd64obsd_trapframe_sniffer
 456 };
 457 \f
 458
 459 static void
 460 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 461 {
 462   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 463
 464   amd64_init_abi (info, gdbarch);
 465   obsd_init_abi (info, gdbarch);
 466
 467   /* Initialize general-purpose register set details.  */
 468   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 469   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 470   tdep->sizeof_gregset = 24 * 8;
 471
 472   tdep->jb_pc_offset = 7 * 8;
 473
 474   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 475   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 476   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 477   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 478
 479   /* OpenBSD provides a user-level threads implementation.  */
 480   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 481   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 482
 483   /* OpenBSD uses SVR4-style shared libraries.  */
 484   set_solib_svr4_fetch_link_map_offsets
 485     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 486
 487   /* Unwind kernel trap frames correctly.  */
 488   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 489 }
 490
 491 /* Traditional (a.out) NetBSD-style core dumps.  */
 492
 493 static void
 494 amd64obsd_core_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 495 {
 496   amd64obsd_init_abi (info, gdbarch);
 497
 498   set_gdbarch_regset_from_core_section
 499     (gdbarch, amd64obsd_regset_from_core_section);
 500 }
 501 \f
 502
 503 /* Provide a prototype to silence -Wmissing-prototypes.  */
 504 void _initialize_amd64obsd_tdep (void);
 505
 506 void
 507 _initialize_amd64obsd_tdep (void)
 508 {
 509   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 510   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 511
 512   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 513                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 514
 515   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 516   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 517                           GDB_OSABI_NETBSD_AOUT, amd64obsd_core_init_abi);
 518 }