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   LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x89, 0x00, 0x00, 0x00,     /*  mov $0x89,%rax */
  39   LINUX_SIGTRAMP_INSN1, 0x05    /* syscall */
  40 };
  41
  42 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
  43
  44 /* If PC is in a sigtramp routine, return the address of the start of
  45    the routine.  Otherwise, return 0.  */
  46
  47 static CORE_ADDR
  48 x86_64_linux_sigtramp_start (CORE_ADDR pc)
  49 {
  50   unsigned char buf[LINUX_SIGTRAMP_LEN];
  51   if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  52     return 0;
  53
  54   if (buf[0] != LINUX_SIGTRAMP_INSN0)
  55     {
  56       if (buf[0] != LINUX_SIGTRAMP_INSN1)
  57         return 0;
  58
  59       pc -= LINUX_SIGTRAMP_OFFSET1;
  60
  61       if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  62         return 0;
  63     }
  64
  65   if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
  66     return 0;
  67
  68   return pc;
  69 }
  70
  71 #define LINUX_SIGINFO_SIZE 128
  72
  73 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
  74 #define LINUX_UCONTEXT_SIGCONTEXT_OFFSET (36)
  75
  76 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
  77    address of the associated sigcontext structure.  */
  78 CORE_ADDR
  79 x86_64_linux_sigcontext_addr (struct frame_info *frame)
  80 {
  81   CORE_ADDR pc;
  82
  83   pc = x86_64_linux_sigtramp_start (frame->pc);
  84   if (pc)
  85     {
  86       if (frame->next)
  87         /* If this isn't the top frame, the next frame must be for the
  88            signal handler itself.  The sigcontext structure is part of
  89            the user context. */
  90         return frame->next->frame + LINUX_SIGINFO_SIZE +
  91           LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  92
  93
  94       /* This is the top frame. */
  95       return read_register (SP_REGNUM) + LINUX_SIGINFO_SIZE +
  96         LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  97
  98     }
  99
 100   error ("Couldn't recognize signal trampoline.");
 101   return 0;
 102 }
 103
 104 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
 105 #define LINUX_SIGCONTEXT_PC_OFFSET (136)
 106
 107 /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
 108    saved program counter.  */
 109
 110 CORE_ADDR
 111 x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 112 {
 113   CORE_ADDR addr;
 114
 115   addr = x86_64_linux_sigcontext_addr (frame);
 116   return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 117 }
 118
 119 /* Immediately after a function call, return the saved pc.  */
 120
 121 CORE_ADDR
 122 x86_64_linux_saved_pc_after_call (struct frame_info *frame)
 123 {
 124   if (frame->signal_handler_caller)
 125     return x86_64_linux_sigtramp_saved_pc (frame);
 126
 127   return read_memory_integer (read_register (SP_REGNUM), 8);
 128 }
 129
 130 /* Saved Pc.  Get it from sigcontext if within sigtramp.  */
 131 CORE_ADDR
 132 x86_64_linux_frame_saved_pc (struct frame_info *frame)
 133 {
 134   if (frame->signal_handler_caller)
 135     return x86_64_linux_sigtramp_saved_pc (frame);
 136   return cfi_get_ra (frame);
 137 }