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       1                 :            : /*
       2                 :            :  * Copyright (c) 2013 Denys Vlasenko <vda.linux@googlemail.com>
       3                 :            :  * Copyright (c) 2013-2015 Dmitry V. Levin <ldv@altlinux.org>
       4                 :            :  * All rights reserved.
       5                 :            :  *
       6                 :            :  * Redistribution and use in source and binary forms, with or without
       7                 :            :  * modification, are permitted provided that the following conditions
       8                 :            :  * are met:
       9                 :            :  * 1. Redistributions of source code must retain the above copyright
      10                 :            :  *    notice, this list of conditions and the following disclaimer.
      11                 :            :  * 2. Redistributions in binary form must reproduce the above copyright
      12                 :            :  *    notice, this list of conditions and the following disclaimer in the
      13                 :            :  *    documentation and/or other materials provided with the distribution.
      14                 :            :  * 3. The name of the author may not be used to endorse or promote products
      15                 :            :  *    derived from this software without specific prior written permission.
      16                 :            :  *
      17                 :            :  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
      18                 :            :  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
      19                 :            :  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
      20                 :            :  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
      21                 :            :  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
      22                 :            :  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      23                 :            :  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      24                 :            :  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      25                 :            :  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
      26                 :            :  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      27                 :            :  */
      28                 :            : 
      29                 :            : /*
      30                 :            :  * PTRACE_GETREGSET was added to the kernel in v2.6.25,
      31                 :            :  * a PTRACE_GETREGS based fallback is provided for old kernels.
      32                 :            :  */
      33                 :            : static int
      34                 :          0 : getregs_old(pid_t pid)
      35                 :            : {
      36                 :            :         /* Use old method, with unreliable heuristical detection of 32-bitness. */
      37                 :          0 :         long r = ptrace(PTRACE_GETREGS, pid, NULL, &x86_64_regs);
      38         [ #  # ]:          0 :         if (r)
      39                 :          0 :                 return r;
      40                 :            : 
      41         [ #  # ]:          0 :         if (x86_64_regs.cs == 0x23) {
      42                 :          0 :                 x86_io.iov_len = sizeof(i386_regs);
      43                 :            :                 /*
      44                 :            :                  * The order is important: i386_regs and x86_64_regs
      45                 :            :                  * are overlaid in memory!
      46                 :            :                  */
      47                 :          0 :                 i386_regs.ebx = x86_64_regs.rbx;
      48                 :          0 :                 i386_regs.ecx = x86_64_regs.rcx;
      49                 :          0 :                 i386_regs.edx = x86_64_regs.rdx;
      50                 :          0 :                 i386_regs.esi = x86_64_regs.rsi;
      51                 :          0 :                 i386_regs.edi = x86_64_regs.rdi;
      52                 :          0 :                 i386_regs.ebp = x86_64_regs.rbp;
      53                 :          0 :                 i386_regs.eax = x86_64_regs.rax;
      54                 :            :                 /* i386_regs.xds = x86_64_regs.ds; unused by strace */
      55                 :            :                 /* i386_regs.xes = x86_64_regs.es; ditto... */
      56                 :            :                 /* i386_regs.xfs = x86_64_regs.fs; */
      57                 :            :                 /* i386_regs.xgs = x86_64_regs.gs; */
      58                 :          0 :                 i386_regs.orig_eax = x86_64_regs.orig_rax;
      59                 :          0 :                 i386_regs.eip = x86_64_regs.rip;
      60                 :            :                 /* i386_regs.xcs = x86_64_regs.cs; */
      61                 :            :                 /* i386_regs.eflags = x86_64_regs.eflags; */
      62                 :          0 :                 i386_regs.esp = x86_64_regs.rsp;
      63                 :            :                 /* i386_regs.xss = x86_64_regs.ss; */
      64                 :            :         } else {
      65                 :          0 :                 x86_io.iov_len = sizeof(x86_64_regs);
      66                 :            :         }
      67                 :          0 :         return 0;
      68                 :            : }