gdb/x86-64-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux running on x86-64, for GDB.
   2
   3    Copyright 2001, 2003 Free Software Foundation, Inc.
   4
   5    Contributed by Jiri Smid, SuSE Labs.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "inferior.h"
  26 #include "gdbcore.h"
  27 #include "gdb_string.h"
  28 #include "regcache.h"
  29 #include "x86-64-tdep.h"
  30 #include "dwarf2cfi.h"
  31 #include "osabi.h"
  32
  33 #define LINUX_SIGTRAMP_INSN0 (0x48)     /* mov $NNNNNNNN,%rax */
  34 #define LINUX_SIGTRAMP_OFFSET0 (0)
  35 #define LINUX_SIGTRAMP_INSN1 (0x0f)     /* syscall */
  36 #define LINUX_SIGTRAMP_OFFSET1 (7)
  37
  38 static const unsigned char linux_sigtramp_code[] = {
  39   /*  mov $__NR_rt_sigreturn,%rax */
  40   LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
  41   /* syscall */
  42   LINUX_SIGTRAMP_INSN1, 0x05
  43 };
  44
  45 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
  46
  47 /* If PC is in a sigtramp routine, return the address of the start of
  48    the routine.  Otherwise, return 0.  */
  49
  50 static CORE_ADDR
  51 x86_64_linux_sigtramp_start (CORE_ADDR pc)
  52 {
  53   unsigned char buf[LINUX_SIGTRAMP_LEN];
  54   if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  55     return 0;
  56
  57   if (buf[0] != LINUX_SIGTRAMP_INSN0)
  58     {
  59       if (buf[0] != LINUX_SIGTRAMP_INSN1)
  60         return 0;
  61
  62       pc -= LINUX_SIGTRAMP_OFFSET1;
  63
  64       if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  65         return 0;
  66     }
  67
  68   if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
  69     return 0;
  70
  71   return pc;
  72 }
  73
  74 #define LINUX_SIGINFO_SIZE 0
  75
  76 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
  77 #define LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
  78
  79 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
  80 #define LINUX_SIGCONTEXT_PC_OFFSET 128
  81 #define LINUX_SIGCONTEXT_FP_OFFSET 120
  82
  83 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
  84    address of the associated sigcontext structure.  */
  85 static CORE_ADDR
  86 x86_64_linux_sigcontext_addr (struct frame_info *frame)
  87 {
  88   CORE_ADDR pc;
  89   ULONGEST rsp;
  90
  91   pc = x86_64_linux_sigtramp_start (get_frame_pc (frame));
  92   if (pc)
  93     {
  94       if (get_next_frame (frame))
  95         /* If this isn't the top frame, the next frame must be for the
  96            signal handler itself.  The sigcontext structure is part of
  97            the user context. */
  98         return get_frame_base (get_next_frame (frame)) + LINUX_SIGINFO_SIZE +
  99           LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 100
 101
 102       /* This is the top frame. */
 103       rsp = read_register (SP_REGNUM);
 104       return rsp + LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 105
 106     }
 107
 108   error ("Couldn't recognize signal trampoline.");
 109   return 0;
 110 }
 111
 112 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
 113    saved program counter.  */
 114
 115 static CORE_ADDR
 116 x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 117 {
 118   CORE_ADDR addr;
 119
 120   addr = x86_64_linux_sigcontext_addr (frame);
 121   return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 122 }
 123
 124 /* Immediately after a function call, return the saved pc.  */
 125
 126 CORE_ADDR
 127 x86_64_linux_saved_pc_after_call (struct frame_info *frame)
 128 {
 129   if ((get_frame_type (frame) == SIGTRAMP_FRAME))
 130     return x86_64_linux_sigtramp_saved_pc (frame);
 131
 132   return read_memory_integer (read_register (SP_REGNUM), 8);
 133 }
 134
 135 /* Saved Pc.  Get it from sigcontext if within sigtramp.  */
 136 CORE_ADDR
 137 x86_64_linux_frame_saved_pc (struct frame_info *frame)
 138 {
 139   if ((get_frame_type (frame) == SIGTRAMP_FRAME))
 140     return x86_64_linux_sigtramp_saved_pc (frame);
 141   return cfi_get_ra (frame);
 142 }
 143
 144 /* Return whether PC is in a GNU/Linux sigtramp routine.  */
 145
 146 int
 147 x86_64_linux_in_sigtramp (CORE_ADDR pc, char *name)
 148 {
 149   if (name)
 150     return strcmp ("__restore_rt", name) == 0;
 151
 152   return (x86_64_linux_sigtramp_start (pc) != 0);
 153 }
 154
 155 CORE_ADDR
 156 x86_64_linux_frame_chain (struct frame_info *fi)
 157 {
 158   ULONGEST addr;
 159   CORE_ADDR fp, pc;
 160
 161   if (!(get_frame_type (fi) == SIGTRAMP_FRAME))
 162     {
 163       fp = cfi_frame_chain (fi);
 164       if (fp)
 165         return fp;
 166       else
 167         addr = get_frame_base (fi);
 168     }
 169   else
 170     addr = get_frame_base (get_next_frame (fi));
 171
 172   addr += LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 173
 174   fp = read_memory_integer (addr + LINUX_SIGCONTEXT_FP_OFFSET, 8) + 8;
 175
 176   return fp;
 177 }
 178
 179 CORE_ADDR
 180 x86_64_init_frame_pc (int fromleaf, struct frame_info *fi)
 181 {
 182   CORE_ADDR addr;
 183
 184   if (get_next_frame (fi)
 185       && (get_frame_type (get_next_frame (fi)) == SIGTRAMP_FRAME))
 186     {
 187       addr = get_frame_base (get_next_frame (get_next_frame (fi)))
 188         + LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 189       return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 190     }
 191   else
 192     return cfi_init_frame_pc (fromleaf, fi);
 193 }
 194 \f
 195
 196 static void
 197 x86_64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 198 {
 199   x86_64_init_abi (info, gdbarch);
 200 }
 201
 202 /* Provide a prototype to silence -Wmissing-prototypes.  */
 203 extern void _initialize_x86_64_linux_tdep (void);
 204
 205 void
 206 _initialize_x86_64_linux_tdep (void)
 207 {
 208   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_LINUX,
 209                           x86_64_linux_init_abi);
 210 }