gdb/x86-64-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux running on x86-64, for GDB.
   2
   3    Copyright 2001, 2003, 2004 Free Software Foundation, Inc.
   4    Contributed by Jiri Smid, SuSE Labs.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "inferior.h"
  25 #include "gdbcore.h"
  26 #include "regcache.h"
  27 #include "osabi.h"
  28
  29 #include "gdb_string.h"
  30
  31 #include "x86-64-tdep.h"
  32 #include "x86-64-linux-tdep.h"
  33
  34 /* Register indexes to 'struct user' come from <sys/reg.h>.  */
  35
  36 #define USER_R15    0
  37 #define USER_R14    1
  38 #define USER_R13    2
  39 #define USER_R12    3
  40 #define USER_RBP    4
  41 #define USER_RBX    5
  42 #define USER_R11    6
  43 #define USER_R10    7
  44 #define USER_R9     8
  45 #define USER_R8     9
  46 #define USER_RAX    10
  47 #define USER_RCX    11
  48 #define USER_RDX    12
  49 #define USER_RSI    13
  50 #define USER_RDI    14
  51 #define USER_RIP    16
  52 #define USER_CS     17
  53 #define USER_EFLAGS 18
  54 #define USER_RSP    19
  55 #define USER_SS     20
  56 #define USER_DS     23
  57 #define USER_ES     24
  58 #define USER_FS     25
  59 #define USER_GS     26
  60
  61 /* Mapping between the general-purpose registers in `struct user'
  62    format and GDB's register array layout.  */
  63
  64 static int user_to_gdb_regmap[] =
  65 {
  66   USER_RAX, USER_RBX, USER_RCX, USER_RDX,
  67   USER_RSI, USER_RDI, USER_RBP, USER_RSP,
  68   USER_R8, USER_R9, USER_R10, USER_R11,
  69   USER_R12, USER_R13, USER_R14, USER_R15,
  70   USER_RIP, USER_EFLAGS,
  71   USER_CS, USER_SS,
  72   USER_DS, USER_ES, USER_FS, USER_GS
  73 };
  74
  75 /* Fill GDB's register array with the general-purpose register values
  76    in *GREGSETP.  */
  77
  78 void
  79 x86_64_linux_supply_gregset (char *regp)
  80 {
  81   int i;
  82
  83   for (i = 0; i < X86_64_NUM_GREGS; i++)
  84     supply_register (i, regp + (user_to_gdb_regmap[i] * 8));
  85 }
  86
  87 /* Fill register REGNO (if it is a general-purpose register) in
  88    *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
  89    do this for all registers.  */
  90
  91 void
  92 x86_64_linux_fill_gregset (char *regp, int regno)
  93 {
  94   int i;
  95
  96   for (i = 0; i < X86_64_NUM_GREGS; i++)
  97     if (regno == -1 || regno == i)
  98       regcache_collect (i, regp + (user_to_gdb_regmap[i] * 8));
  99 }
 100
 101 /* The register sets used in GNU/Linux ELF core-dumps are identical to
 102    the register sets used by `ptrace'.  The corresponding types are
 103    `elf_gregset_t' for the general-purpose registers (with
 104    `elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
 105    for the floating-point registers.  */
 106
 107 static void
 108 fetch_core_registers (char *core_reg_sect, unsigned core_reg_size,
 109                          int which, CORE_ADDR ignore)
 110 {
 111   switch (which)
 112     {
 113     case 0:  /* Integer registers.  */
 114       if (core_reg_size != 216)
 115         warning ("Wrong size register set in core file.");
 116       else
 117         x86_64_linux_supply_gregset (core_reg_sect);
 118       break;
 119
 120     case 2:  /* Floating point registers.  */
 121     case 3:  /* "Extended" floating point registers.  This is gdb-speak
 122                 for SSE/SSE2. */
 123       if (core_reg_size != 512)
 124         warning ("Wrong size XMM register set in core file.");
 125       else
 126         x86_64_supply_fxsave (current_regcache, -1, core_reg_sect);
 127       break;
 128
 129     default:
 130       /* Don't know what kind of register request this is; just ignore it.  */
 131       break;
 132     }
 133 }
 134
 135 static struct core_fns x86_64_core_fns =
 136 {
 137   bfd_target_elf_flavour,               /* core_flavour */
 138   default_check_format,                 /* check_format */
 139   default_core_sniffer,                 /* core_sniffer */
 140   fetch_core_registers,                 /* core_read_registers */
 141   NULL                                  /* next */
 142 };
 143
 144 #define LINUX_SIGTRAMP_INSN0    0x48    /* mov $NNNNNNNN, %rax */
 145 #define LINUX_SIGTRAMP_OFFSET0  0
 146 #define LINUX_SIGTRAMP_INSN1    0x0f    /* syscall */
 147 #define LINUX_SIGTRAMP_OFFSET1  7
 148
 149 static const unsigned char linux_sigtramp_code[] =
 150 {
 151   /* mov $__NR_rt_sigreturn, %rax */
 152   LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
 153   /* syscall */
 154   LINUX_SIGTRAMP_INSN1, 0x05
 155 };
 156
 157 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
 158
 159 /* If PC is in a sigtramp routine, return the address of the start of
 160    the routine.  Otherwise, return 0.  */
 161
 162 static CORE_ADDR
 163 x86_64_linux_sigtramp_start (CORE_ADDR pc)
 164 {
 165   unsigned char buf[LINUX_SIGTRAMP_LEN];
 166
 167   /* We only recognize a signal trampoline if PC is at the start of
 168      one of the two instructions.  We optimize for finding the PC at
 169      the start, as will be the case when the trampoline is not the
 170      first frame on the stack.  We assume that in the case where the
 171      PC is not at the start of the instruction sequence, there will be
 172      a few trailing readable bytes on the stack.  */
 173
 174   if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
 175     return 0;
 176
 177   if (buf[0] != LINUX_SIGTRAMP_INSN0)
 178     {
 179       if (buf[0] != LINUX_SIGTRAMP_INSN1)
 180         return 0;
 181
 182       pc -= LINUX_SIGTRAMP_OFFSET1;
 183
 184       if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
 185         return 0;
 186     }
 187
 188   if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
 189     return 0;
 190
 191   return pc;
 192 }
 193
 194 /* Return whether PC is in a GNU/Linux sigtramp routine.  */
 195
 196 static int
 197 x86_64_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
 198 {
 199   /* If we have NAME, we can optimize the search.  The trampoline is
 200      named __restore_rt.  However, it isn't dynamically exported from
 201      the shared C library, so the trampoline may appear to be part of
 202      the preceding function.  This should always be sigaction,
 203      __sigaction, or __libc_sigaction (all aliases to the same
 204      function).  */
 205   if (name == NULL || strstr (name, "sigaction") != NULL)
 206     return (x86_64_linux_sigtramp_start (pc) != 0);
 207
 208   return (strcmp ("__restore_rt", name) == 0);
 209 }
 210
 211 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
 212 #define X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
 213
 214 /* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp
 215    routine, return the address of the associated sigcontext structure.  */
 216
 217 static CORE_ADDR
 218 x86_64_linux_sigcontext_addr (struct frame_info *next_frame)
 219 {
 220   CORE_ADDR sp;
 221   char buf[8];
 222
 223   frame_unwind_register (next_frame, SP_REGNUM, buf);
 224   sp = extract_unsigned_integer (buf, 8);
 225
 226   /* The sigcontext structure is part of the user context.  A pointer
 227      to the user context is passed as the third argument to the signal
 228      handler, i.e. in %rdx.  Unfortunately %rdx isn't preserved across
 229      function calls so we can't use it.  Fortunately the user context
 230      is part of the signal frame and the unwound %rsp directly points
 231      at it.  */
 232   return sp + X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 233 }
 234 \f
 235
 236 /* From <asm/sigcontext.h>.  */
 237 static int x86_64_linux_sc_reg_offset[] =
 238 {
 239   13 * 8,                       /* %rax */
 240   11 * 8,                       /* %rbx */
 241   14 * 8,                       /* %rcx */
 242   12 * 8,                       /* %rdx */
 243   9 * 8,                        /* %rsi */
 244   8 * 8,                        /* %rdi */
 245   10 * 8,                       /* %rbp */
 246   15 * 8,                       /* %rsp */
 247   0 * 8,                        /* %r8 */
 248   1 * 8,                        /* %r9 */
 249   2 * 8,                        /* %r10 */
 250   3 * 8,                        /* %r11 */
 251   4 * 8,                        /* %r12 */
 252   5 * 8,                        /* %r13 */
 253   6 * 8,                        /* %r14 */
 254   7 * 8,                        /* %r15 */
 255   16 * 8,                       /* %rip */
 256   17 * 8,                       /* %eflags */
 257
 258   /* FIXME: kettenis/2002030531: The registers %cs, %fs and %gs are
 259      available in `struct sigcontext'.  However, they only occupy two
 260      bytes instead of four, which makes using them here rather
 261      difficult.  Leave them out for now.  */
 262   -1,                           /* %cs */
 263   -1,                           /* %ss */
 264   -1,                           /* %ds */
 265   -1,                           /* %es */
 266   -1,                           /* %fs */
 267   -1                            /* %gs */
 268 };
 269
 270 static void
 271 x86_64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 272 {
 273   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 274   x86_64_init_abi (info, gdbarch);
 275
 276   set_gdbarch_pc_in_sigtramp (gdbarch, x86_64_linux_pc_in_sigtramp);
 277
 278   tdep->sigcontext_addr = x86_64_linux_sigcontext_addr;
 279   tdep->sc_reg_offset = x86_64_linux_sc_reg_offset;
 280   tdep->sc_num_regs = ARRAY_SIZE (x86_64_linux_sc_reg_offset);
 281 }
 282 \f
 283
 284 /* Provide a prototype to silence -Wmissing-prototypes.  */
 285 extern void _initialize_x86_64_linux_tdep (void);
 286
 287 void
 288 _initialize_x86_64_linux_tdep (void)
 289 {
 290   add_core_fns (&x86_64_core_fns);
 291
 292   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_LINUX,
 293                           x86_64_linux_init_abi);
 294 }