1 /*
2 * Copyright (c) 2013 Denys Vlasenko <vda.linux@googlemail.com>
3 * Copyright (c) 2013-2015 Dmitry V. Levin <ldv@altlinux.org>
4 * Copyright (c) 2015-2018 The strace developers.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 /*
31 * PTRACE_GETREGSET was added to the kernel in v2.6.25,
32 * a PTRACE_GETREGS based fallback is provided for old kernels.
33 */
34 static int
getregs_old(struct tcb * tcp)35 getregs_old(struct tcb *tcp)
36 {
37 /* Use old method, with unreliable heuristical detection of 32-bitness. */
38 long r = ptrace(PTRACE_GETREGS, tcp->pid, NULL, &x86_64_regs);
39 if (r)
40 return r;
41
42 if (x86_64_regs.cs == 0x23) {
43 x86_io.iov_len = sizeof(i386_regs);
44 /*
45 * The order is important: i386_regs and x86_64_regs
46 * are overlaid in memory!
47 */
48 i386_regs.ebx = x86_64_regs.rbx;
49 i386_regs.ecx = x86_64_regs.rcx;
50 i386_regs.edx = x86_64_regs.rdx;
51 i386_regs.esi = x86_64_regs.rsi;
52 i386_regs.edi = x86_64_regs.rdi;
53 i386_regs.ebp = x86_64_regs.rbp;
54 i386_regs.eax = x86_64_regs.rax;
55 /* i386_regs.xds = x86_64_regs.ds; unused by strace */
56 /* i386_regs.xes = x86_64_regs.es; ditto... */
57 /* i386_regs.xfs = x86_64_regs.fs; */
58 /* i386_regs.xgs = x86_64_regs.gs; */
59 i386_regs.orig_eax = x86_64_regs.orig_rax;
60 i386_regs.eip = x86_64_regs.rip;
61 /* i386_regs.xcs = x86_64_regs.cs; */
62 /* i386_regs.eflags = x86_64_regs.eflags; */
63 i386_regs.esp = x86_64_regs.rsp;
64 /* i386_regs.xss = x86_64_regs.ss; */
65 } else {
66 x86_io.iov_len = sizeof(x86_64_regs);
67 }
68 return 0;
69 }
70