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