gdb/x86-64-linux-tdep.c

   1 /* Target-dependent code for Linux running on x86-64, for GDB.
   2    Copyright 2001
   3    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 "x86-64-tdep.h"
  28 #include "dwarf2cfi.h"
  29
  30 #define LINUX_SIGTRAMP_INSN0 (0x48)     /* mov $NNNNNNNN,%rax */
  31 #define LINUX_SIGTRAMP_OFFSET0 (0)
  32 #define LINUX_SIGTRAMP_INSN1 (0x0f)     /* syscall */
  33 #define LINUX_SIGTRAMP_OFFSET1 (7)
  34
  35 static const unsigned char linux_sigtramp_code[] = {
  36   LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x89, 0x00, 0x00, 0x00,     /*  mov $0x89,%rax */
  37   LINUX_SIGTRAMP_INSN1, 0x05    /* syscall */
  38 };
  39
  40 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
  41
  42 /* If PC is in a sigtramp routine, return the address of the start of
  43    the routine.  Otherwise, return 0.  */
  44
  45 static CORE_ADDR
  46 x86_64_linux_sigtramp_start (CORE_ADDR pc)
  47 {
  48   unsigned char buf[LINUX_SIGTRAMP_LEN];
  49   if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  50     return 0;
  51
  52   if (buf[0] != LINUX_SIGTRAMP_INSN0)
  53     {
  54       if (buf[0] != LINUX_SIGTRAMP_INSN1)
  55         return 0;
  56
  57       pc -= LINUX_SIGTRAMP_OFFSET1;
  58
  59       if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  60         return 0;
  61     }
  62
  63   if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
  64     return 0;
  65
  66   return pc;
  67 }
  68
  69 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
  70 #define LINUX_UCONTEXT_SIGCONTEXT_OFFSET (36)
  71
  72 /* Assuming FRAME is for a Linux sigtramp routine, return the address
  73    of the associated sigcontext structure.  */
  74 CORE_ADDR
  75 x86_64_linux_sigcontext_addr (struct frame_info *frame)
  76 {
  77   CORE_ADDR pc;
  78
  79   pc = x86_64_linux_sigtramp_start (frame->pc);
  80   if (pc)
  81     {
  82       if (frame->next)
  83         /* If this isn't the top frame, the next frame must be for the
  84            signal handler itself.  The sigcontext structure is part of
  85            the user context. */
  86         return frame->next->frame + sizeof (struct siginfo) +
  87           LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  88
  89
  90       /* This is the top frame. */
  91       return read_register (SP_REGNUM) + sizeof (struct siginfo) +
  92         LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  93
  94     }
  95
  96   error ("Couldn't recognize signal trampoline.");
  97   return 0;
  98 }
  99
 100 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
 101 #define LINUX_SIGCONTEXT_PC_OFFSET (136)
 102
 103 /* Assuming FRAME is for a Linux sigtramp routine, return the saved
 104    program counter.  */
 105
 106 CORE_ADDR
 107 x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 108 {
 109   CORE_ADDR addr;
 110
 111   addr = x86_64_linux_sigcontext_addr (frame);
 112   return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 113 }
 114
 115 /* Immediately after a function call, return the saved pc.  */
 116
 117 CORE_ADDR
 118 x86_64_linux_saved_pc_after_call (struct frame_info *frame)
 119 {
 120   if (frame->signal_handler_caller)
 121     return x86_64_linux_sigtramp_saved_pc (frame);
 122
 123   return read_memory_integer (read_register (SP_REGNUM), 8);
 124 }
 125
 126 /* Saved Pc.  Get it from sigcontext if within sigtramp.  */
 127 CORE_ADDR
 128 x86_64_linux_frame_saved_pc (struct frame_info *frame)
 129 {
 130   if (frame->signal_handler_caller)
 131     return x86_64_linux_sigtramp_saved_pc (frame);
 132   return cfi_get_ra (frame);
 133 }