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
getregs_old(pid_t pid)34 getregs_old(pid_t pid)
35 {
36 /* Use old method, with unreliable heuristical detection of 32-bitness. */
37 long r = ptrace(PTRACE_GETREGS, pid, NULL, &x86_64_regs);
38 if (r)
39 return r;
40
41 if (x86_64_regs.cs == 0x23) {
42 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 i386_regs.ebx = x86_64_regs.rbx;
48 i386_regs.ecx = x86_64_regs.rcx;
49 i386_regs.edx = x86_64_regs.rdx;
50 i386_regs.esi = x86_64_regs.rsi;
51 i386_regs.edi = x86_64_regs.rdi;
52 i386_regs.ebp = x86_64_regs.rbp;
53 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 i386_regs.orig_eax = x86_64_regs.orig_rax;
59 i386_regs.eip = x86_64_regs.rip;
60 /* i386_regs.xcs = x86_64_regs.cs; */
61 /* i386_regs.eflags = x86_64_regs.eflags; */
62 i386_regs.esp = x86_64_regs.rsp;
63 /* i386_regs.xss = x86_64_regs.ss; */
64 } else {
65 x86_io.iov_len = sizeof(x86_64_regs);
66 }
67 return 0;
68 }
69