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 #define LINUX_SIGINFO_SIZE 128
  70
  71 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
  72 #define LINUX_UCONTEXT_SIGCONTEXT_OFFSET (36)
  73
  74 /* Assuming FRAME is for a Linux sigtramp routine, return the address
  75    of the associated sigcontext structure.  */
  76 CORE_ADDR
  77 x86_64_linux_sigcontext_addr (struct frame_info *frame)
  78 {
  79   CORE_ADDR pc;
  80
  81   pc = x86_64_linux_sigtramp_start (frame->pc);
  82   if (pc)
  83     {
  84       if (frame->next)
  85         /* If this isn't the top frame, the next frame must be for the
  86            signal handler itself.  The sigcontext structure is part of
  87            the user context. */
  88         return frame->next->frame + LINUX_SIGINFO_SIZE +
  89           LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  90
  91
  92       /* This is the top frame. */
  93       return read_register (SP_REGNUM) + LINUX_SIGINFO_SIZE +
  94         LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
  95
  96     }
  97
  98   error ("Couldn't recognize signal trampoline.");
  99   return 0;
 100 }
 101
 102 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
 103 #define LINUX_SIGCONTEXT_PC_OFFSET (136)
 104
 105 /* Assuming FRAME is for a Linux sigtramp routine, return the saved
 106    program counter.  */
 107
 108 CORE_ADDR
 109 x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 110 {
 111   CORE_ADDR addr;
 112
 113   addr = x86_64_linux_sigcontext_addr (frame);
 114   return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);
 115 }
 116
 117 /* Immediately after a function call, return the saved pc.  */
 118
 119 CORE_ADDR
 120 x86_64_linux_saved_pc_after_call (struct frame_info *frame)
 121 {
 122   if (frame->signal_handler_caller)
 123     return x86_64_linux_sigtramp_saved_pc (frame);
 124
 125   return read_memory_integer (read_register (SP_REGNUM), 8);
 126 }
 127
 128 /* Saved Pc.  Get it from sigcontext if within sigtramp.  */
 129 CORE_ADDR
 130 x86_64_linux_frame_saved_pc (struct frame_info *frame)
 131 {
 132   if (frame->signal_handler_caller)
 133     return x86_64_linux_sigtramp_saved_pc (frame);
 134   return cfi_get_ra (frame);
 135 }