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