gdb/x86-64-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux running on x86-64, for GDB.
   2
   3    Copyright 2001 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
  32 #define LINUX_SIGTRAMP_INSN0 (0x48)     /* mov $NNNNNNNN,%rax */
  33 #define LINUX_SIGTRAMP_OFFSET0 (0)
  34 #define LINUX_SIGTRAMP_INSN1 (0x0f)     /* syscall */
  35 #define LINUX_SIGTRAMP_OFFSET1 (7)
  36
  37 static const unsigned char linux_sigtramp_code[] = {
  38   /*  mov $__NR_rt_sigreturn,%rax */
  39   LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
  40   /* syscall */
  41   LINUX_SIGTRAMP_INSN1, 0x05
  42 };
  43
  44 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
  45
  46 /* If PC is in a sigtramp routine, return the address of the start of
  47    the routine.  Otherwise, return 0.  */
  48
  49 static CORE_ADDR
  50 x86_64_linux_sigtramp_start (CORE_ADDR pc)
  51 {
  52   unsigned char buf[LINUX_SIGTRAMP_LEN];
  53   if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  54     return 0;
  55
  56   if (buf[0] != LINUX_SIGTRAMP_INSN0)
  57     {
  58       if (buf[0] != LINUX_SIGTRAMP_INSN1)
  59         return 0;
  60
  61       pc -= LINUX_SIGTRAMP_OFFSET1;
  62
  63       if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  64         return 0;
  65     }
  66
  67   if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
  68     return 0;
  69
  70   return pc;
  71 }
  72
  73 #define LINUX_SIGINFO_SIZE 0
  74
  75 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
  76 #define LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
  77
  78 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
  79 #define LINUX_SIGCONTEXT_PC_OFFSET 128
  80 #define LINUX_SIGCONTEXT_FP_OFFSET 120
  81
  82 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
  83    address of the associated sigcontext structure.  */
  84 static CORE_ADDR
  85 x86_64_linux_sigcontext_addr (struct frame_info *frame)
  86 {
  87   CORE_ADDR pc;
  88   ULONGEST rsp;
  89
  90   pc = x86_64_linux_sigtramp_start (get_frame_pc (frame));
  91   if (pc)
  92     {
  93       if (frame->next)
  94         /* If this isn't the top frame, the next frame must be for the
  95            signal handler itself.  The sigcontext structure is part of
  96            the user context. */
  97         return frame->next->frame + LINUX_SIGINFO_SIZE +
  98           LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  99
 100
 101       /* This is the top frame. */
 102       rsp = read_register (SP_REGNUM);
 103       return rsp + LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 104
 105     }
 106
 107   error ("Couldn't recognize signal trampoline.");
 108   return 0;
 109 }
 110
 111 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
 112    saved program counter.  */
 113
 114 static CORE_ADDR
 115 x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 116 {
 117   CORE_ADDR addr;
 118
 119   addr = x86_64_linux_sigcontext_addr (frame);
 120   return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 121 }
 122
 123 /* Immediately after a function call, return the saved pc.  */
 124
 125 CORE_ADDR
 126 x86_64_linux_saved_pc_after_call (struct frame_info *frame)
 127 {
 128   if ((get_frame_type (frame) == SIGTRAMP_FRAME))
 129     return x86_64_linux_sigtramp_saved_pc (frame);
 130
 131   return read_memory_integer (read_register (SP_REGNUM), 8);
 132 }
 133
 134 /* Saved Pc.  Get it from sigcontext if within sigtramp.  */
 135 CORE_ADDR
 136 x86_64_linux_frame_saved_pc (struct frame_info *frame)
 137 {
 138   if ((get_frame_type (frame) == SIGTRAMP_FRAME))
 139     return x86_64_linux_sigtramp_saved_pc (frame);
 140   return cfi_get_ra (frame);
 141 }
 142
 143 /* Return whether PC is in a GNU/Linux sigtramp routine.  */
 144
 145 int
 146 x86_64_linux_in_sigtramp (CORE_ADDR pc, char *name)
 147 {
 148   if (name)
 149     return STREQ ("__restore_rt", name);
 150
 151   return (x86_64_linux_sigtramp_start (pc) != 0);
 152 }
 153
 154 CORE_ADDR
 155 x86_64_linux_frame_chain (struct frame_info *fi)
 156 {
 157   ULONGEST addr;
 158   CORE_ADDR fp, pc;
 159
 160   if (!(get_frame_type (fi) == SIGTRAMP_FRAME))
 161     {
 162       fp = cfi_frame_chain (fi);
 163       if (fp)
 164         return fp;
 165       else
 166         addr = fi->frame;
 167     }
 168   else
 169     addr = fi->next->frame;
 170
 171   addr += LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 172
 173   fp = read_memory_integer (addr + LINUX_SIGCONTEXT_FP_OFFSET, 8) + 8;
 174
 175   return fp;
 176 }
 177
 178 CORE_ADDR
 179 x86_64_init_frame_pc (int fromleaf, struct frame_info *fi)
 180 {
 181   CORE_ADDR addr;
 182
 183   if (get_next_frame (fi) && (get_frame_type (fi->next) == SIGTRAMP_FRAME))
 184     {
 185       addr = get_frame_base (get_next_frame (get_next_frame (fi)))
 186         + LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 187       return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 188     }
 189   else
 190     return cfi_init_frame_pc (fromleaf, fi);
 191 }
 192 \f
 193
 194 static void
 195 x86_64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 196 {
 197   x86_64_init_abi (info, gdbarch);
 198 }
 199
 200 /* Provide a prototype to silence -Wmissing-prototypes.  */
 201 extern void _initialize_x86_64_linux_tdep (void);
 202
 203 void
 204 _initialize_x86_64_linux_tdep (void)
 205 {
 206   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_LINUX,
 207                           x86_64_linux_init_abi);
 208 }