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/*
* Copyright (c) 2002 Andi Kleen <ak@suse.de>
* Copyright (c) 2002 Michal Ludvig <mludvig@suse.cz>
* Copyright (c) 2002 Roland McGrath <roland@redhat.com>
* Copyright (c) 2008-2013 Denys Vlasenko <vda.linux@googlemail.com>
* Copyright (c) 2012 H.J. Lu <hongjiu.lu@intel.com>
* Copyright (c) 2010-2015 Dmitry V. Levin <ldv@altlinux.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef X86_64
# define X32_PERSONALITY_NUMBER 2
#else
# define X32_PERSONALITY_NUMBER 0
#endif
/* Return codes: 1 - ok, 0 - ignore, other - error. */
static int
arch_get_scno(struct tcb *tcp)
{
long scno = 0;
unsigned int currpers;
#ifndef __X32_SYSCALL_BIT
# define __X32_SYSCALL_BIT 0x40000000
#endif
#if 1
/*
* GETREGSET of NT_PRSTATUS tells us regset size,
* which unambiguously detects i386.
*
* Linux kernel distinguishes x86-64 and x32 processes
* solely by looking at __X32_SYSCALL_BIT:
* arch/x86/include/asm/compat.h::is_x32_task():
* if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
* return true;
*/
if (x86_io.iov_len == sizeof(i386_regs)) {
scno = i386_regs.orig_eax;
currpers = 1;
} else {
scno = x86_64_regs.orig_rax;
currpers = 0;
if (scno & __X32_SYSCALL_BIT) {
/*
* Syscall number -1 requires special treatment:
* it might be a side effect of SECCOMP_RET_ERRNO
* filtering that sets orig_rax to -1
* in some versions of linux kernel.
* If that is the case, then
* __X32_SYSCALL_BIT logic does not apply.
*/
if ((long long) x86_64_regs.orig_rax != -1) {
scno -= __X32_SYSCALL_BIT;
currpers = 2;
} else {
# ifdef X32
currpers = 2;
# endif
}
}
}
#elif 0
/*
* cs = 0x33 for long mode (native 64 bit and x32)
* cs = 0x23 for compatibility mode (32 bit)
* ds = 0x2b for x32 mode (x86-64 in 32 bit)
*/
scno = x86_64_regs.orig_rax;
switch (x86_64_regs.cs) {
case 0x23: currpers = 1; break;
case 0x33:
if (x86_64_regs.ds == 0x2b) {
currpers = 2;
scno &= ~__X32_SYSCALL_BIT;
} else
currpers = 0;
break;
default:
error_msg("Unknown value CS=0x%08X while "
"detecting personality of process PID=%d",
(int)x86_64_regs.cs, tcp->pid);
currpers = current_personality;
break;
}
#elif 0
/*
* This version analyzes the opcode of a syscall instruction.
* (int 0x80 on i386 vs. syscall on x86-64)
* It works, but is too complicated, and strictly speaking, unreliable.
*/
unsigned long call, rip = x86_64_regs.rip;
/* sizeof(syscall) == sizeof(int 0x80) == 2 */
rip -= 2;
errno = 0;
call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0);
if (errno)
perror_msg("ptrace_peektext failed");
switch (call & 0xffff) {
/* x86-64: syscall = 0x0f 0x05 */
case 0x050f: currpers = 0; break;
/* i386: int 0x80 = 0xcd 0x80 */
case 0x80cd: currpers = 1; break;
default:
currpers = current_personality;
error_msg("Unknown syscall opcode (0x%04X) while "
"detecting personality of process PID=%d",
(int)call, tcp->pid);
break;
}
#endif
#ifdef X32
/*
* If we are built for a x32 system, then personality 0 is x32
* (not x86_64), and stracing of x86_64 apps is not supported.
* Stracing of i386 apps is still supported.
*/
if (currpers == 0) {
error_msg("syscall_%lu(...) in unsupported "
"64-bit mode of process PID=%d", scno, tcp->pid);
return 0;
}
currpers &= ~2; /* map 2,1 to 0,1 */
#endif /* X32 */
update_personality(tcp, currpers);
tcp->scno = scno;
return 1;
}
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