gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright 2003, 2004, 2005 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., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "gdbcore.h"
  25 #include "symtab.h"
  26 #include "objfiles.h"
  27 #include "osabi.h"
  28 #include "regset.h"
  29 #include "target.h"
  30
  31 #include "gdb_assert.h"
  32 #include "gdb_string.h"
  33
  34 #include "amd64-tdep.h"
  35 #include "i387-tdep.h"
  36 #include "solib-svr4.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   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  46
  47   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  48
  49   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  50   amd64_supply_fxsave (regcache, regnum,
  51                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  52 }
  53
  54 static const struct regset *
  55 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  56                                     const char *sect_name, size_t sect_size)
  57 {
  58   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  59
  60   /* OpenBSD core dumps don't use seperate register sets for the
  61      general-purpose and floating-point registers.  */
  62
  63   if (strcmp (sect_name, ".reg") == 0
  64       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  65     {
  66       if (tdep->gregset == NULL)
  67         tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);
  68       return tdep->gregset;
  69     }
  70
  71   return NULL;
  72 }
  73 \f
  74
  75 /* Support for signal handlers.  */
  76
  77 /* Default page size.  */
  78 static const int amd64obsd_page_size = 4096;
  79
  80 /* Return whether the frame preceding NEXT_FRAME corresponds to an
  81    OpenBSD sigtramp routine.  */
  82
  83 static int
  84 amd64obsd_sigtramp_p (struct frame_info *next_frame)
  85 {
  86   CORE_ADDR pc = frame_pc_unwind (next_frame);
  87   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  88   const gdb_byte sigreturn[] =
  89   {
  90     0x48, 0xc7, 0xc0,
  91     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  92     0xcd, 0x80                  /* int $0x80 */
  93   };
  94   size_t buflen = (sizeof sigreturn) + 1;
  95   gdb_byte *buf;
  96   char *name;
  97
  98   /* If the function has a valid symbol name, it isn't a
  99      trampoline.  */
 100   find_pc_partial_function (pc, &name, NULL, NULL);
 101   if (name != NULL)
 102     return 0;
 103
 104   /* If the function lives in a valid section (even without a starting
 105      point) it isn't a trampoline.  */
 106   if (find_pc_section (pc) != NULL)
 107     return 0;
 108
 109   /* If we can't read the instructions at START_PC, return zero.  */
 110   buf = alloca ((sizeof sigreturn) + 1);
 111   if (!safe_frame_unwind_memory (next_frame, start_pc + 6, buf, buflen))
 112     return 0;
 113
 114   /* Check for sigreturn(2).  Depending on how the assembler encoded
 115      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 116      7.  */
 117   if (memcmp (buf, sigreturn, sizeof sigreturn)
 118       && memcpy (buf + 1, sigreturn, sizeof sigreturn))
 119     return 0;
 120
 121   return 1;
 122 }
 123
 124 /* Assuming NEXT_FRAME is for a frame following a BSD sigtramp
 125    routine, return the address of the associated sigcontext structure.  */
 126
 127 static CORE_ADDR
 128 amd64obsd_sigcontext_addr (struct frame_info *next_frame)
 129 {
 130   CORE_ADDR pc = frame_pc_unwind (next_frame);
 131   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 132
 133   /* The %rsp register points at `struct sigcontext' upon entry of a
 134      signal trampoline.  The relevant part of the trampoline is
 135
 136         call    *%rax
 137         movq    %rsp, %rdi
 138         pushq   %rdi
 139         movq    $SYS_sigreturn,%rax
 140         int     $0x80
 141
 142      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 143      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 144
 145   if (offset > 5)
 146     return frame_unwind_register_unsigned (next_frame, AMD64_RDI_REGNUM);
 147   else
 148     return frame_unwind_register_unsigned (next_frame, AMD64_RSP_REGNUM);
 149 }
 150 \f
 151 /* OpenBSD 3.5 or later.  */
 152
 153 /* Mapping between the general-purpose registers in `struct reg'
 154    format and GDB's register cache layout.  */
 155
 156 /* From <machine/reg.h>.  */
 157 int amd64obsd_r_reg_offset[] =
 158 {
 159   14 * 8,                       /* %rax */
 160   13 * 8,                       /* %rbx */
 161   3 * 8,                        /* %rcx */
 162   2 * 8,                        /* %rdx */
 163   1 * 8,                        /* %rsi */
 164   0 * 8,                        /* %rdi */
 165   12 * 8,                       /* %rbp */
 166   15 * 8,                       /* %rsp */
 167   4 * 8,                        /* %r8 .. */
 168   5 * 8,
 169   6 * 8,
 170   7 * 8,
 171   8 * 8,
 172   9 * 8,
 173   10 * 8,
 174   11 * 8,                       /* ... %r15 */
 175   16 * 8,                       /* %rip */
 176   17 * 8,                       /* %eflags */
 177   18 * 8,                       /* %cs */
 178   19 * 8,                       /* %ss */
 179   20 * 8,                       /* %ds */
 180   21 * 8,                       /* %es */
 181   22 * 8,                       /* %fs */
 182   23 * 8                        /* %gs */
 183 };
 184
 185 /* From <machine/signal.h>.  */
 186 static int amd64obsd_sc_reg_offset[] =
 187 {
 188   14 * 8,                       /* %rax */
 189   13 * 8,                       /* %rbx */
 190   3 * 8,                        /* %rcx */
 191   2 * 8,                        /* %rdx */
 192   1 * 8,                        /* %rsi */
 193   0 * 8,                        /* %rdi */
 194   12 * 8,                       /* %rbp */
 195   24 * 8,                       /* %rsp */
 196   4 * 8,                        /* %r8 ... */
 197   5 * 8,
 198   6 * 8,
 199   7 * 8,
 200   8 * 8,
 201   9 * 8,
 202   10 * 8,
 203   11 * 8,                       /* ... %r15 */
 204   21 * 8,                       /* %rip */
 205   23 * 8,                       /* %eflags */
 206   22 * 8,                       /* %cs */
 207   25 * 8,                       /* %ss */
 208   18 * 8,                       /* %ds */
 209   17 * 8,                       /* %es */
 210   16 * 8,                       /* %fs */
 211   15 * 8                        /* %gs */
 212 };
 213
 214 static void
 215 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 216 {
 217   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 218
 219   amd64_init_abi (info, gdbarch);
 220
 221   /* Initialize general-purpose register set details.  */
 222   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 223   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 224   tdep->sizeof_gregset = 24 * 8;
 225
 226   set_gdbarch_regset_from_core_section (gdbarch,
 227                                         amd64obsd_regset_from_core_section);
 228
 229   tdep->jb_pc_offset = 7 * 8;
 230
 231   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 232   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 233   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 234   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 235
 236   /* OpenBSD uses SVR4-style shared libraries.  */
 237   set_solib_svr4_fetch_link_map_offsets
 238     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 239 }
 240 \f
 241
 242 /* Provide a prototype to silence -Wmissing-prototypes.  */
 243 void _initialize_amd64obsd_tdep (void);
 244
 245 void
 246 _initialize_amd64obsd_tdep (void)
 247 {
 248   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 249   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 250
 251   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 252                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 253
 254   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 255   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 256                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 257 }