gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003-2015 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 "obsd-tdep.h"
  33 #include "amd64-tdep.h"
  34 #include "i387-tdep.h"
  35 #include "solib-svr4.h"
  36 #include "bsd-uthread.h"
  37
  38 /* Support for core dumps.  */
  39
  40 static void
  41 amd64obsd_supply_regset (const struct regset *regset,
  42                          struct regcache *regcache, int regnum,
  43                          const void *regs, size_t len)
  44 {
  45   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  46   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  47
  48   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  49
  50   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  51   amd64_supply_fxsave (regcache, regnum,
  52                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  53 }
  54
  55 static const struct regset amd64obsd_combined_regset =
  56   {
  57     NULL, amd64obsd_supply_regset, NULL
  58   };
  59
  60 static void
  61 amd64obsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
  62                                         iterate_over_regset_sections_cb *cb,
  63                                         void *cb_data,
  64                                         const struct regcache *regcache)
  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   cb (".reg", tdep->sizeof_gregset + I387_SIZEOF_FXSAVE,
  72       &amd64obsd_combined_regset, NULL, cb_data);
  73 }
  74 \f
  75
  76 /* Support for signal handlers.  */
  77
  78 /* Default page size.  */
  79 static const int amd64obsd_page_size = 4096;
  80
  81 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  82    routine.  */
  83
  84 static int
  85 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  86 {
  87   CORE_ADDR pc = get_frame_pc (this_frame);
  88   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  89   const gdb_byte osigreturn[] =
  90   {
  91     0x48, 0xc7, 0xc0,
  92     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  93     0xcd, 0x80                  /* int $0x80 */
  94   };
  95   const gdb_byte sigreturn[] =
  96   {
  97     0x48, 0xc7, 0xc0,
  98     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  99     0x0f, 0x05                  /* syscall */
 100   };
 101   size_t buflen = (sizeof sigreturn) + 1;
 102   gdb_byte *buf;
 103   const char *name;
 104
 105   /* If the function has a valid symbol name, it isn't a
 106      trampoline.  */
 107   find_pc_partial_function (pc, &name, NULL, NULL);
 108   if (name != NULL)
 109     return 0;
 110
 111   /* If the function lives in a valid section (even without a starting
 112      point) it isn't a trampoline.  */
 113   if (find_pc_section (pc) != NULL)
 114     return 0;
 115
 116   /* If we can't read the instructions at START_PC, return zero.  */
 117   buf = alloca ((sizeof sigreturn) + 1);
 118   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 119     return 0;
 120
 121   /* Check for sigreturn(2).  Depending on how the assembler encoded
 122      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 123      7.  OpenBSD 5.0 and later use the `syscall' instruction.  Older
 124      versions use `int $0x80'.  Check for both.  */
 125   if (memcmp (buf, sigreturn, sizeof sigreturn)
 126       && memcmp (buf + 1, sigreturn, sizeof sigreturn)
 127       && memcmp (buf, osigreturn, sizeof osigreturn)
 128       && memcmp (buf + 1, osigreturn, sizeof osigreturn))
 129     return 0;
 130
 131   return 1;
 132 }
 133
 134 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 135    address of the associated sigcontext structure.  */
 136
 137 static CORE_ADDR
 138 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 139 {
 140   CORE_ADDR pc = get_frame_pc (this_frame);
 141   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 142
 143   /* The %rsp register points at `struct sigcontext' upon entry of a
 144      signal trampoline.  The relevant part of the trampoline is
 145
 146         call    *%rax
 147         movq    %rsp, %rdi
 148         pushq   %rdi
 149         movq    $SYS_sigreturn,%rax
 150         int     $0x80
 151
 152      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 153      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 154
 155   if (offset > 5)
 156     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 157   else
 158     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 159 }
 160 \f
 161 /* OpenBSD 3.5 or later.  */
 162
 163 /* Mapping between the general-purpose registers in `struct reg'
 164    format and GDB's register cache layout.  */
 165
 166 /* From <machine/reg.h>.  */
 167 int amd64obsd_r_reg_offset[] =
 168 {
 169   14 * 8,                       /* %rax */
 170   13 * 8,                       /* %rbx */
 171   3 * 8,                        /* %rcx */
 172   2 * 8,                        /* %rdx */
 173   1 * 8,                        /* %rsi */
 174   0 * 8,                        /* %rdi */
 175   12 * 8,                       /* %rbp */
 176   15 * 8,                       /* %rsp */
 177   4 * 8,                        /* %r8 ..  */
 178   5 * 8,
 179   6 * 8,
 180   7 * 8,
 181   8 * 8,
 182   9 * 8,
 183   10 * 8,
 184   11 * 8,                       /* ... %r15 */
 185   16 * 8,                       /* %rip */
 186   17 * 8,                       /* %eflags */
 187   18 * 8,                       /* %cs */
 188   19 * 8,                       /* %ss */
 189   20 * 8,                       /* %ds */
 190   21 * 8,                       /* %es */
 191   22 * 8,                       /* %fs */
 192   23 * 8                        /* %gs */
 193 };
 194
 195 /* From <machine/signal.h>.  */
 196 static int amd64obsd_sc_reg_offset[] =
 197 {
 198   14 * 8,                       /* %rax */
 199   13 * 8,                       /* %rbx */
 200   3 * 8,                        /* %rcx */
 201   2 * 8,                        /* %rdx */
 202   1 * 8,                        /* %rsi */
 203   0 * 8,                        /* %rdi */
 204   12 * 8,                       /* %rbp */
 205   24 * 8,                       /* %rsp */
 206   4 * 8,                        /* %r8 ...  */
 207   5 * 8,
 208   6 * 8,
 209   7 * 8,
 210   8 * 8,
 211   9 * 8,
 212   10 * 8,
 213   11 * 8,                       /* ... %r15 */
 214   21 * 8,                       /* %rip */
 215   23 * 8,                       /* %eflags */
 216   22 * 8,                       /* %cs */
 217   25 * 8,                       /* %ss */
 218   18 * 8,                       /* %ds */
 219   17 * 8,                       /* %es */
 220   16 * 8,                       /* %fs */
 221   15 * 8                        /* %gs */
 222 };
 223
 224 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 225 static int amd64obsd_uthread_reg_offset[] =
 226 {
 227   19 * 8,                       /* %rax */
 228   16 * 8,                       /* %rbx */
 229   18 * 8,                       /* %rcx */
 230   17 * 8,                       /* %rdx */
 231   14 * 8,                       /* %rsi */
 232   13 * 8,                       /* %rdi */
 233   15 * 8,                       /* %rbp */
 234   -1,                           /* %rsp */
 235   12 * 8,                       /* %r8 ...  */
 236   11 * 8,
 237   10 * 8,
 238   9 * 8,
 239   8 * 8,
 240   7 * 8,
 241   6 * 8,
 242   5 * 8,                        /* ... %r15 */
 243   20 * 8,                       /* %rip */
 244   4 * 8,                        /* %eflags */
 245   21 * 8,                       /* %cs */
 246   -1,                           /* %ss */
 247   3 * 8,                        /* %ds */
 248   2 * 8,                        /* %es */
 249   1 * 8,                        /* %fs */
 250   0 * 8                         /* %gs */
 251 };
 252
 253 /* Offset within the thread structure where we can find the saved
 254    stack pointer (%esp).  */
 255 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 256
 257 static void
 258 amd64obsd_supply_uthread (struct regcache *regcache,
 259                           int regnum, CORE_ADDR addr)
 260 {
 261   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 262   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 263   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 264   CORE_ADDR sp = 0;
 265   gdb_byte buf[8];
 266   int i;
 267
 268   gdb_assert (regnum >= -1);
 269
 270   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 271     {
 272       int offset;
 273
 274       /* Fetch stack pointer from thread structure.  */
 275       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 276
 277       /* Adjust the stack pointer such that it looks as if we just
 278          returned from _thread_machdep_switch.  */
 279       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 280       store_unsigned_integer (buf, 8, byte_order, sp + offset);
 281       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 282     }
 283
 284   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 285     {
 286       if (amd64obsd_uthread_reg_offset[i] != -1
 287           && (regnum == -1 || regnum == i))
 288         {
 289           /* Fetch stack pointer from thread structure (if we didn't
 290              do so already).  */
 291           if (sp == 0)
 292             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 293
 294           /* Read the saved register from the stack frame.  */
 295           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 296           regcache_raw_supply (regcache, i, buf);
 297         }
 298     }
 299 }
 300
 301 static void
 302 amd64obsd_collect_uthread (const struct regcache *regcache,
 303                            int regnum, CORE_ADDR addr)
 304 {
 305   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 306   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 307   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 308   CORE_ADDR sp = 0;
 309   gdb_byte buf[8];
 310   int i;
 311
 312   gdb_assert (regnum >= -1);
 313
 314   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 315     {
 316       int offset;
 317
 318       /* Calculate the stack pointer (frame pointer) that will be
 319          stored into the thread structure.  */
 320       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 321       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 322       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
 323
 324       /* Store the stack pointer.  */
 325       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
 326
 327       /* The stack pointer was (potentially) modified.  Make sure we
 328          build a proper stack frame.  */
 329       regnum = -1;
 330     }
 331
 332   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 333     {
 334       if (amd64obsd_uthread_reg_offset[i] != -1
 335           && (regnum == -1 || regnum == i))
 336         {
 337           /* Fetch stack pointer from thread structure (if we didn't
 338              calculate it already).  */
 339           if (sp == 0)
 340             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
 341
 342           /* Write the register into the stack frame.  */
 343           regcache_raw_collect (regcache, i, buf);
 344           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 345         }
 346     }
 347 }
 348 /* Kernel debugging support.  */
 349
 350 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 351    `struct sigcontext'.  */
 352 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 353
 354 static struct trad_frame_cache *
 355 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 356 {
 357   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 358   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 359   struct trad_frame_cache *cache;
 360   CORE_ADDR func, sp, addr;
 361   ULONGEST cs;
 362   const char *name;
 363   int i;
 364
 365   if (*this_cache)
 366     return *this_cache;
 367
 368   cache = trad_frame_cache_zalloc (this_frame);
 369   *this_cache = cache;
 370
 371   func = get_frame_func (this_frame);
 372   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 373
 374   find_pc_partial_function (func, &name, NULL, NULL);
 375   if (name && startswith (name, "Xintr"))
 376     addr = sp + 8;              /* It's an interrupt frame.  */
 377   else
 378     addr = sp;
 379
 380   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 381     if (amd64obsd_tf_reg_offset[i] != -1)
 382       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 383
 384   /* Read %cs from trap frame.  */
 385   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 386   cs = read_memory_unsigned_integer (addr, 8, byte_order);
 387   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 388     {
 389       /* Trap from user space; terminate backtrace.  */
 390       trad_frame_set_id (cache, outer_frame_id);
 391     }
 392   else
 393     {
 394       /* Construct the frame ID using the function start.  */
 395       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 396     }
 397
 398   return cache;
 399 }
 400
 401 static void
 402 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 403                              void **this_cache, struct frame_id *this_id)
 404 {
 405   struct trad_frame_cache *cache =
 406     amd64obsd_trapframe_cache (this_frame, this_cache);
 407
 408   trad_frame_get_id (cache, this_id);
 409 }
 410
 411 static struct value *
 412 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 413                                    void **this_cache, int regnum)
 414 {
 415   struct trad_frame_cache *cache =
 416     amd64obsd_trapframe_cache (this_frame, this_cache);
 417
 418   return trad_frame_get_register (cache, this_frame, regnum);
 419 }
 420
 421 static int
 422 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 423                              struct frame_info *this_frame,
 424                              void **this_prologue_cache)
 425 {
 426   ULONGEST cs;
 427   const char *name;
 428
 429   /* Check Current Privilege Level and bail out if we're not executing
 430      in kernel space.  */
 431   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 432   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 433     return 0;
 434
 435   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 436   return (name && ((strcmp (name, "calltrap") == 0)
 437                    || (strcmp (name, "osyscall1") == 0)
 438                    || (strcmp (name, "Xsyscall") == 0)
 439                    || (startswith (name, "Xintr"))));
 440 }
 441
 442 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 443   /* FIXME: kettenis/20051219: This really is more like an interrupt
 444      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 445      which really is not what we want here.  */
 446   NORMAL_FRAME,
 447   default_frame_unwind_stop_reason,
 448   amd64obsd_trapframe_this_id,
 449   amd64obsd_trapframe_prev_register,
 450   NULL,
 451   amd64obsd_trapframe_sniffer
 452 };
 453 \f
 454
 455 static void
 456 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 457 {
 458   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 459
 460   amd64_init_abi (info, gdbarch);
 461   obsd_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_iterate_over_regset_sections
 495     (gdbarch, amd64obsd_iterate_over_regset_sections);
 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 }