LCOV - code coverage report
Current view: top level - strace/linux/x86_64 - get_scno.c (source / functions) Hit Total Coverage
Test: strace-4.18.0.129.97bbb Code Coverage Lines: 14 14 100.0 %
Date: 2017-07-31 03:46:08 Functions: 1 1 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 5 6 83.3 %

           Branch data     Line data    Source code
       1                 :            : /*
       2                 :            :  * Copyright (c) 2002 Andi Kleen <ak@suse.de>
       3                 :            :  * Copyright (c) 2002 Michal Ludvig <mludvig@suse.cz>
       4                 :            :  * Copyright (c) 2002 Roland McGrath <roland@redhat.com>
       5                 :            :  * Copyright (c) 2008-2013 Denys Vlasenko <vda.linux@googlemail.com>
       6                 :            :  * Copyright (c) 2012 H.J. Lu <hongjiu.lu@intel.com>
       7                 :            :  * Copyright (c) 2010-2015 Dmitry V. Levin <ldv@altlinux.org>
       8                 :            :  * Copyright (c) 2015-2017 The strace developers.
       9                 :            :  * All rights reserved.
      10                 :            :  *
      11                 :            :  * Redistribution and use in source and binary forms, with or without
      12                 :            :  * modification, are permitted provided that the following conditions
      13                 :            :  * are met:
      14                 :            :  * 1. Redistributions of source code must retain the above copyright
      15                 :            :  *    notice, this list of conditions and the following disclaimer.
      16                 :            :  * 2. Redistributions in binary form must reproduce the above copyright
      17                 :            :  *    notice, this list of conditions and the following disclaimer in the
      18                 :            :  *    documentation and/or other materials provided with the distribution.
      19                 :            :  * 3. The name of the author may not be used to endorse or promote products
      20                 :            :  *    derived from this software without specific prior written permission.
      21                 :            :  *
      22                 :            :  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
      23                 :            :  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
      24                 :            :  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
      25                 :            :  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
      26                 :            :  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
      27                 :            :  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      28                 :            :  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      29                 :            :  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      30                 :            :  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
      31                 :            :  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      32                 :            :  */
      33                 :            : 
      34                 :            : #ifdef X86_64
      35                 :            : # define X32_PERSONALITY_NUMBER 2
      36                 :            : #else
      37                 :            : # define X32_PERSONALITY_NUMBER 0
      38                 :            : #endif
      39                 :            : 
      40                 :            : /* Return codes: 1 - ok, 0 - ignore, other - error. */
      41                 :            : static int
      42                 :   37085583 : arch_get_scno(struct tcb *tcp)
      43                 :            : {
      44                 :   37085583 :         kernel_ulong_t scno = 0;
      45                 :            :         unsigned int currpers;
      46                 :            : 
      47                 :            : #ifndef __X32_SYSCALL_BIT
      48                 :            : # define __X32_SYSCALL_BIT      0x40000000
      49                 :            : #endif
      50                 :            : 
      51                 :            : #if 1
      52                 :            :         /*
      53                 :            :          * GETREGSET of NT_PRSTATUS tells us regset size,
      54                 :            :          * which unambiguously detects i386.
      55                 :            :          *
      56                 :            :          * Linux kernel distinguishes x86-64 and x32 processes
      57                 :            :          * solely by looking at __X32_SYSCALL_BIT:
      58                 :            :          * arch/x86/include/asm/compat.h::is_x32_task():
      59                 :            :          * if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
      60                 :            :          *      return true;
      61                 :            :          */
      62         [ +  + ]:   37085583 :         if (x86_io.iov_len == sizeof(i386_regs)) {
      63                 :    1639328 :                 scno = i386_regs.orig_eax;
      64                 :    1639328 :                 currpers = 1;
      65                 :            :         } else {
      66                 :   35446255 :                 scno = x86_64_regs.orig_rax;
      67                 :   35446255 :                 currpers = 0;
      68         [ +  + ]:   35446255 :                 if (scno & __X32_SYSCALL_BIT) {
      69                 :            :                         /*
      70                 :            :                          * Syscall number -1 requires special treatment:
      71                 :            :                          * it might be a side effect of SECCOMP_RET_ERRNO
      72                 :            :                          * filtering that sets orig_rax to -1
      73                 :            :                          * in some versions of linux kernel.
      74                 :            :                          * If that is the case, then
      75                 :            :                          * __X32_SYSCALL_BIT logic does not apply.
      76                 :            :                          */
      77         [ +  - ]:          2 :                         if ((long long) x86_64_regs.orig_rax != -1) {
      78                 :          2 :                                 scno -= __X32_SYSCALL_BIT;
      79                 :          2 :                                 currpers = 2;
      80                 :            :                         } else {
      81                 :            : # ifdef X32
      82                 :            :                                 currpers = 2;
      83                 :            : # endif
      84                 :            :                         }
      85                 :            :                 }
      86                 :            :         }
      87                 :            : 
      88                 :            : #elif 0
      89                 :            :         /*
      90                 :            :          * cs = 0x33 for long mode (native 64 bit and x32)
      91                 :            :          * cs = 0x23 for compatibility mode (32 bit)
      92                 :            :          * ds = 0x2b for x32 mode (x86-64 in 32 bit)
      93                 :            :          */
      94                 :            :         scno = x86_64_regs.orig_rax;
      95                 :            :         switch (x86_64_regs.cs) {
      96                 :            :                 case 0x23:
      97                 :            :                         currpers = 1;
      98                 :            :                         break;
      99                 :            :                 case 0x33:
     100                 :            :                         if (x86_64_regs.ds == 0x2b) {
     101                 :            :                                 currpers = 2;
     102                 :            :                                 scno &= ~__X32_SYSCALL_BIT;
     103                 :            :                         } else
     104                 :            :                                 currpers = 0;
     105                 :            :                         break;
     106                 :            :                 default:
     107                 :            :                         error_msg("Unknown value CS=0x%08X while "
     108                 :            :                                   "detecting personality of process PID=%d",
     109                 :            :                                   (int)x86_64_regs.cs, tcp->pid);
     110                 :            :                         currpers = current_personality;
     111                 :            :                         break;
     112                 :            :         }
     113                 :            : #elif 0
     114                 :            :         /*
     115                 :            :          * This version analyzes the opcode of a syscall instruction.
     116                 :            :          * (int 0x80 on i386 vs. syscall on x86-64)
     117                 :            :          * It works, but is too complicated, and strictly speaking, unreliable.
     118                 :            :          */
     119                 :            :         unsigned long call, rip = x86_64_regs.rip;
     120                 :            :         /* sizeof(syscall) == sizeof(int 0x80) == 2 */
     121                 :            :         rip -= 2;
     122                 :            :         errno = 0;
     123                 :            :         call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0);
     124                 :            :         if (errno)
     125                 :            :                 perror_msg("ptrace_peektext failed");
     126                 :            :         switch (call & 0xffff) {
     127                 :            :                 /* x86-64: syscall = 0x0f 0x05 */
     128                 :            :                 case 0x050f:
     129                 :            :                         currpers = 0;
     130                 :            :                         break;
     131                 :            :                 /* i386: int 0x80 = 0xcd 0x80 */
     132                 :            :                 case 0x80cd:
     133                 :            :                         currpers = 1;
     134                 :            :                         break;
     135                 :            :                 default:
     136                 :            :                         currpers = current_personality;
     137                 :            :                         error_msg("Unknown syscall opcode (0x%04X) while "
     138                 :            :                                   "detecting personality of process PID=%d",
     139                 :            :                                   (int)call, tcp->pid);
     140                 :            :                         break;
     141                 :            :         }
     142                 :            : #endif
     143                 :            : 
     144                 :            : #ifdef X32
     145                 :            :         /*
     146                 :            :          * If we are built for a x32 system, then personality 0 is x32
     147                 :            :          * (not x86_64), and stracing of x86_64 apps is not supported.
     148                 :            :          * Stracing of i386 apps is still supported.
     149                 :            :          */
     150                 :            :         if (currpers == 0) {
     151                 :            :                 error_msg("syscall_%" PRI_klu "(...) in unsupported "
     152                 :            :                           "64-bit mode of process PID=%d", scno, tcp->pid);
     153                 :            :                 return 0;
     154                 :            :         }
     155                 :            :         currpers &= ~2; /* map 2,1 to 0,1 */
     156                 :            : #endif /* X32 */
     157                 :            : 
     158                 :   37085583 :         update_personality(tcp, currpers);
     159                 :   37085583 :         tcp->scno = scno;
     160                 :   37085583 :         return 1;
     161                 :            : }

Generated by: LCOV version 1.11